CN110128250B - Process for preparing cyclohexanone - Google Patents

Process for preparing cyclohexanone Download PDF

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CN110128250B
CN110128250B CN201810136077.XA CN201810136077A CN110128250B CN 110128250 B CN110128250 B CN 110128250B CN 201810136077 A CN201810136077 A CN 201810136077A CN 110128250 B CN110128250 B CN 110128250B
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catalyst bed
titanium
molecular sieve
aluminum
catalyst
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CN110128250A (en
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史春风
林民
朱斌
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
    • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
    • C07C45/29—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation of hydroxy groups
    • C07C45/294—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation of hydroxy groups with hydrogen peroxide

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  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Catalysts (AREA)

Abstract

The invention relates to the field of cyclohexanone production, and discloses a method for preparing cyclohexanone, which comprises the following steps: flowing a liquid mixture comprising cyclohexanol and an oxidant through a catalyst bed under oxidation reaction conditions; the catalyst bed layer comprises a first catalyst bed layer and a second catalyst bed layer, and the first catalyst bed layer is positioned at the upstream of the second catalyst bed layer by taking the flowing direction of the liquid mixture as a reference; the first catalyst bed layer is filled with a titanium-silicon molecular sieve; the second catalyst bed layer is filled with a titanium-silicon-aluminum molecular sieve. The method of the invention can obtain higher oxidant conversion rate and cyclohexanone selectivity.

Description

Process for preparing cyclohexanone
Technical Field
The invention belongs to the field of cyclohexanone production, and particularly relates to an application of a titanium-silicon-aluminum molecular sieve in cyclohexanol oxidation, in particular to a method for preparing cyclohexanone.
Background
Cyclohexanone is an important chemical raw material, and is widely applied to industries of fibers, synthetic rubber, industrial coatings, medicines, pesticides and organic solvents. Especially due to the rapid development of the polyamide industry, the demand for cyclohexanone as an intermediate for the preparation of nylon-6 and nylon-66 is above 100 million tons every year worldwide. Currently, there are three main routes for cyclohexanone production: cyclohexane liquid phase oxidation, phenol hydrogenation and benzene partial hydrogenation, while cyclohexane oxidation is the main process for industrially producing cyclohexanone, accounting for more than 90%. However, this production process is also considered to be the least efficient of all chemical industrial processes. The process of synthesizing cyclohexanone by oxidizing cyclohexane is one of the key and bottleneck for restricting the production of caprolactam.
There are generally three methods for industrially producing cyclohexanone by oxidation of cyclohexane: one is catalytic oxidation with cobalt salt as catalyst, which has high cyclohexane converting rate, but the formation of cobalt adipate makes the reactor easy to scale and is eliminated basically. And secondly, the boric acid catalytic oxidation method has high capital investment, high energy consumption, very complex process and great operation difficulty, and can easily cause serious blockage of equipment and pipelines. And thirdly, the problem of reactor scaling is effectively avoided by using air for direct oxidation without catalytic oxidation, the method is widely applied in industry, but the process is complex, the number of intermediate steps is large, the cyclohexane conversion rate is low, the cyclohexane circulation rate is large, the energy consumption is high, the pollution is large, and particularly in the decomposition process of cyclohexyl hydroperoxide, the cyclohexanone selectivity is poor, and the yield is low. In addition, a large amount of waste lye generated in the process is difficult to treat and is still a worldwide environmental protection problem.
Disclosure of Invention
The invention aims to overcome the defects of high energy consumption, high pollution, low cyclohexanone selectivity and the like of the conventional method for preparing cyclohexanone, and provides a method for preparing cyclohexanone.
The inventor of the present invention unexpectedly found in the research process that, in the process of preparing cyclohexanone by oxidizing cyclohexanol, if a part of titanium-silicon-aluminum molecular sieve is introduced as a catalyst in a reaction system, the conversion rate of cyclohexanol and the selectivity of cyclohexanone can be significantly improved under relatively mild conditions. The present invention has been completed based on this finding.
Accordingly, the present invention provides a process for the preparation of cyclohexanone, which process comprises: flowing a liquid mixture comprising cyclohexanol and an oxidant through a catalyst bed under oxidation reaction conditions; the catalyst bed layer comprises a first catalyst bed layer and a second catalyst bed layer, and the first catalyst bed layer is positioned at the upstream of the second catalyst bed layer by taking the flowing direction of the liquid mixture as a reference; wherein the first catalyst bed layer is filled with a titanium silicalite molecular sieve; the second catalyst bed layer is filled with a titanium-silicon-aluminum molecular sieve.
By matching the titanium silicalite molecular sieve and the titanium silicalite molecular sieve as catalysts, the method can obtain higher oxidant conversion rate and cyclohexanone selectivity even under mild conditions (lower energy consumption), namely, the device can continuously run for a long time, so that the stable running time of the device can be effectively prolonged, and the running cost is reduced. In addition, in the method, the catalyst is easy to recycle, the whole process is environment-friendly, simple and easy to control, no special equipment requirement exists, and the method is beneficial to industrial production and application.
In particular, the inventors of the present invention have found that the use of a titanium-silicon-aluminum catalyst obtained by treating a discharging agent to a specific crystallinity and then heat-treating with other raw materials in the reaction of the present invention can further improve the oxidant conversion and cyclohexanone selectivity.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, combinations of values between the endpoints of each range, between the endpoints of each range and the individual values, and between the individual values can be used to obtain one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The method for preparing cyclohexanone provided by the invention comprises the following steps: flowing a liquid mixture comprising cyclohexanol and an oxidant through a catalyst bed under oxidation reaction conditions; the catalyst bed layer comprises a first catalyst bed layer and a second catalyst bed layer, and the first catalyst bed layer is positioned at the upstream of the second catalyst bed layer by taking the flowing direction of the liquid mixture as a reference;
wherein the first catalyst bed layer is filled with a titanium-silicon molecular sieve; the second catalyst bed layer is filled with a titanium-silicon-aluminum molecular sieve.
According to the method of the present invention, it is preferable that when the target oxidation product selectivity decreases to satisfy the condition 1, the method further comprises performing the adjusting step, and stopping the adjusting step until the target oxidation product selectivity increases to satisfy the condition 2,
Condition 1, selectivity S of target oxidation product at a certain time ttSelectivity S with initial target oxidation product0Ratio S oft/S0S is not less than 0.85t/S0<1；
Condition 2, target oxidation product selectivity S' and initial target oxidation product selectivity S0Ratio S'/S of0S'/S is more than or equal to 0.90≤1；
The adjusting step is to increase the mass content of the oxidizing agent in the liquid mixture.
According to the process of the present invention, more preferably, in Condition 1, St/S0<0.9。
According to the process of the present invention, the mass content of the oxidizing agent in the liquid mixture is more preferably increased in the range of 0.02 to 5%/day.
According to the process of the present invention, various methods can be used to increase the mass content of the oxidizing agent in the liquid mixture. For example: the amount of oxidizing agent added to formulate the liquid mixture can be increased to increase the mass content of oxidizing agent in the liquid mixture. When the oxidizing agent is provided in the form of an oxidizing agent solution, the mass content of the oxidizing agent in the liquid mixture can be increased by increasing the concentration of the oxidizing agent in the oxidizing agent solution, and the amount of the oxidizing agent solution can be kept constant or adjusted accordingly (for example, the amount of the oxidizing agent solution is reduced correspondingly so as to keep the ratio between cyclohexanol and the oxidizing agent constant), as long as the mass content of the oxidizing agent in the liquid mixture is increased. This is particularly useful where the oxidizing agent (e.g., hydrogen peroxide) is provided in the form of an oxidizing agent solution (e.g., hydrogen peroxide), which may be increased by increasing the concentration of the oxidizing agent (e.g., hydrogen peroxide) in the oxidizing agent solution (e.g., hydrogen peroxide). The initial concentration of the oxidant in the oxidant solution may be conventionally selected and may generally be in the range 20 to 70 wt%, preferably 20 to 50 wt%.
According to the method of the present invention, more preferably, the weight ratio of the titanium silicalite molecular sieves filled in the first catalyst bed layer to the titanium silicalite molecular sieves filled in the second catalyst bed layer may be 0.1-20: 1, preferably 0.2 to 10: 1.
according to the process of the present invention, the first catalyst bed and the second catalyst bed may each comprise one or more catalyst beds. When the first catalyst bed layer and/or the second catalyst bed layer contains a plurality of catalyst bed layers, the plurality of catalyst bed layers may be connected in series, may also be connected in parallel, and may also be a combination of series and parallel, for example: the catalyst beds are divided into a plurality of groups, the catalyst beds in each group are connected in series and/or in parallel, and the groups are connected in series and/or in parallel. The first catalyst bed layer and the second catalyst bed layer can be arranged in different areas of the same reactor, and can also be arranged in different reactors.
According to the method of the present invention, the superficial velocities of the liquid mixture flowing through the first catalyst bed layer and the second catalyst bed layer may be the same or different. Preferably, the superficial velocity of the liquid mixture flowing through the first catalyst bed layer is v 1Superficial velocity through the second catalyst bed is v2Wherein v is1＜v2This can further extend the single pass service life of the catalyst. More preferably, v2/v11-10. Further preferably, v2/v1＝2.5-8。
In the present invention, the superficial velocity refers to the mass flow rate (in kg/s) of the liquid mixture and the area (in m) of a certain cross section of the catalyst bed in the whole process of passing through the catalyst bed in unit time2Meter) ratio. In general, the mass of the liquid mixture fed to the fixed-bed reactor per unit time can be taken as the "mass flow rate of the liquid mixture through the entire catalyst bed per unit time". In the present invention, there is no particular requirement for the superficial velocity of the liquid mixture in the first catalyst bed, and it may be generally in the range of 0.001 to 200 kg/(m)2S).
Various methods can be employed to adjust the superficial velocity of the liquid mixture in the first catalyst bed and the second catalyst bed. For example, by selecting the catalyst bedThe cross-sectional area of the layer adjusts the superficial velocity of the liquid mixture. Specifically, the cross-sectional area of the first catalyst bed may be made larger than the cross-sectional area of the second catalyst bed so that v 1＜v2Preferably such that v2/v1Is 1 to 10, more preferably such that v2/v1Is 2.5-8. Methods for determining the cross-sectional area of the catalyst bed based on the desired superficial velocity are well known to those skilled in the art and will not be described in detail herein.
According to the method, when the weight ratio of the titanium silicalite molecular sieve filled in the first catalyst bed layer to the titanium silicalite molecular sieve filled in the second catalyst bed layer is preferably 0.2-10: 1, the ratio of the inner diameter of the first catalyst bed to the inner diameter of the second catalyst bed is preferably 1-6: 1.
according to the process of the invention, the residence time of the liquid mixture in the first catalyst bed is T1The total residence time in the catalyst bed is T, preferably T1and/T is 0.3-0.95. More preferably, T1the/T is 0.45-0.86, so that the one-way service life of the catalyst can be further prolonged, and the selectivity of the target oxidation product is higher.
According to the process of the present invention, the temperature of the first catalyst bed and the temperature of the catalyst bed may be the same or different. From the viewpoint of further improving the selectivity of the target oxidation product and further extending the single-pass service life of the catalyst, it is preferable that the temperature of the first catalyst bed is higher than the temperature of the second catalyst bed. More preferably, the temperature of the first catalyst bed is 4-30 ℃, preferably 5-15 ℃ higher than the temperature of the second catalyst bed.
According to the method, when the catalyst bed layer comprises a first catalyst bed layer and a second catalyst bed layer, fresh materials can be supplemented between the first catalyst bed layer and the second catalyst bed layer according to specific conditions, and when the first catalyst bed layer and/or the second catalyst bed layer are multiple catalyst bed layers, fresh cyclohexanol can be supplemented between the first catalyst bed layer and/or between the second catalyst bed layers according to specific conditions. For example: fresh cyclohexanol, and optionally fresh solvent, is replenished between the first and second catalyst beds, between the first catalyst beds, and/or between the second catalyst beds. However, it should be noted that the liquid mixture at which the superficial velocity is determined refers to a liquid mixture that flows through all of the beds of the first catalyst bed (i.e., throughout the first catalyst bed) and all of the beds of the second catalyst bed (i.e., throughout the second catalyst bed), and does not include fresh material introduced between the first catalyst beds, between the second catalyst beds, and between the first catalyst beds and the second catalyst beds.
According to the method of the invention, the catalyst bed layer can be filled with the molecular sieve only or can contain the molecular sieve and inactive fillers. The amount of the molecular sieve in the catalyst bed layer can be adjusted by filling the inactive filler in the catalyst bed layer, so that the reaction speed is adjusted. When the catalyst bed contains a molecular sieve and inactive filler, the content of inactive filler in the catalyst bed may be 5-95 wt%. The non-active filler means a filler having no or substantially no catalytic activity for oxidation reaction, and specific examples thereof may include, but are not limited to: one or more of quartz sand, ceramic rings, and ceramic chips.
The total amount of molecular sieve (i.e., the total amount of molecular sieve in the first catalyst bed and the second catalyst bed) can be selected based on the specific throughput of the system. Generally, the weight space velocity of cyclohexanol may be 0.1-50h based on total amount of molecular sieve in the first and second catalyst beds-1Preferably 0.2 to 10h-1。
According to the method of the present invention, the oxidizing agent may be any of various substances commonly used to oxidize cyclohexanol. Preferably, the oxidizing agent is a peroxide. The peroxide is a compound containing an-O-O-bond in the molecular structure, and can be selected from hydrogen peroxide, organic peroxide and peracid. The organic peroxide is a substance obtained by replacing one or two hydrogen atoms in a hydrogen peroxide molecule with an organic group. The peracid refers to an organic oxyacid having an-O-bond in its molecular structure. Specific examples of the peroxide may include, but are not limited to: hydrogen peroxide, tert-butyl hydroperoxide, cumene peroxide, cyclohexyl hydroperoxide, peracetic acid and propionic acid. Preferably, the oxidizing agent is hydrogen peroxide, which further reduces the separation cost. The hydrogen peroxide may be hydrogen peroxide in various forms commonly used in the art.
According to the process of the present invention, the hydrogen peroxide is usually added to the reaction system in the form of an aqueous hydrogen peroxide solution having a concentration of 5 to 70% by mass, for example, 27.5%, 30%, 55%, 70%, etc. of an aqueous hydrogen peroxide solution of industrial grade.
The amount of the oxidant may be selected according to the amount of cyclohexanol. Generally, the molar ratio of cyclohexanol to oxidant may be from 0.1 to 20: 1, preferably 0.2 to 10: 1, more preferably 1 to 5: 1.
according to the process of the invention, the liquid mixture may or may not contain a solvent, and preferably also contains at least one solvent, so that the speed and intensity of the reaction can be better controlled. The solvent is not particularly limited in kind, and may be various liquid substances capable of dissolving cyclohexanol and an oxidizing agent or promoting mixing of both, and dissolving a target oxidation product. In general, the solvent may be selected from water, C other than cyclohexanol1-C6Alcohol of (1), C3-C8Ketone and C2-C6A nitrile of (a). Specific examples of the solvent may include, but are not limited to: water, methanol, ethanol, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone and acetonitrile. Preferably, the solvent is selected from water and C except cyclohexanol 1-C6The alcohol of (1). More preferably, the solvent is methanol and/or water.
The amount of the solvent used in the present invention is not particularly limited, and may be selected according to the amounts of the cyclohexanol and the oxidizing agent. Generally, the weight ratio of the solvent to the cyclohexanol may be from 0.1 to 100: 1, preferably 0.2 to 80: 1.
according to the process of the present invention, the oxidation reaction conditions may be selected based on the desired target oxidation product. Specifically, the conditions under which the liquid mixture flows through the first catalyst bed and the second catalyst bed each include: the temperature can be 0-80 ℃, preferably 20-70 ℃; the pressure may be in the range of 0.1 to 3MPa in gauge pressure.
According to the method of the present invention, it is preferable that at least one alkaline substance is further added to the liquid mixture in an amount such that the pH of the liquid mixture is in the range of 6 to 9, thereby achieving a better reaction effect. More preferably, the alkaline substance is added in an amount such that the pH of the liquid mixture is in the range of 6.5-8.5, preferably 6.8-8.2. When the pH of the liquid mixture in contact with the molecular sieve is 6.5 or more (or 7 or more), the above-described effects can still be obtained if the pH of the liquid mixture is further increased by using an alkali. The pH of the liquid mixture means the pH of the liquid mixture measured at 25 ℃ and 1 atm.
Herein, the basic substance means a substance whose aqueous solution has a pH value of more than 7. Specific examples of the basic substance may include, but are not limited to: ammonia (i.e., NH)3) Amine, quaternary ammonium base and M1(OH)n(wherein, M1Is an alkali metal or alkaline earth metal, n is an alkyl group with M1The same integer as the valence of (1).
As the basic substance, ammonia may be introduced in the form of liquid ammonia, an aqueous solution, or a gas. The concentration of ammonia as an aqueous solution (i.e., aqueous ammonia) is not particularly limited and may be conventionally selected, for example, from 1 to 36% by weight.
As the basic substance, amine means a substance formed by partially or totally substituting hydrogen on ammonia with a hydrocarbon group, and includes primary amine, secondary amine and tertiary amine. The amine may in particular be a substance of the formula I and/or C3-C11The heterocyclic amine of (a) is a heterocyclic amine,
Figure BDA0001576316490000081
in the formula I, R1、R2And R3Each may be H or C1-C6Of (e.g. C)1-C6Alkyl group of) and R)1、R2And R3Not H at the same time. Herein, C1-C6Alkyl of (2) includes C1-C6Straight chain alkyl of (2) and C3-C6Specific examples thereof may include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl and n-hexyl.
Specific examples of amines may include, but are not limited to: methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine, diisopropylamine, n-butylamine, di-n-butylamine, tri-n-butylamine, sec-butylamine, diisobutylamine, triisobutylamine, tert-butylamine, n-pentylamine, di-n-pentylamine, tri-n-pentylamine, neopentylamine, isopentylamine, diisopentylamine, triisopentylamine, tert-pentylamine, n-hexylamine, and n-octylamine.
The heterocyclic amine is a compound having a nitrogen atom on the ring and a lone pair of electrons on the nitrogen atom. The heterocyclic amine may be, for example, one or more of substituted or unsubstituted pyrrole, substituted or unsubstituted tetrahydropyrrole, substituted or unsubstituted pyridine, substituted or unsubstituted piperidine, substituted or unsubstituted imidazole, substituted or unsubstituted pyrazole, substituted or unsubstituted quinoline, substituted or unsubstituted dihydroquinoline, substituted or unsubstituted tetrahydroquinoline, substituted or unsubstituted decahydroquinoline, substituted or unsubstituted isoquinoline, and substituted or unsubstituted pyrimidine.
As the basic substance, a quaternary ammonium base may specifically be a substance represented by the following formula II. Specific examples of the quaternary ammonium base may include, but are not limited to: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide (including tetra-n-propylammonium hydroxide and tetraisopropylammonium hydroxide), tetrabutylammonium hydroxide (including tetra-n-butylammonium hydroxide, tetra-sec-butylammonium hydroxide, tetra-isobutyl ammonium hydroxide and tetra-tert-butylammonium hydroxide), and tetrapentylammonium hydroxide.
As the basic substance, M1(OH)nIs a hydroxide of an alkali metal or a hydroxide of an alkaline earth metal, and may be, for example, sodium hydroxide, potassium hydroxide, magnesium hydroxide, barium hydroxide and calcium hydroxide.
According to the method of the present invention, the alkaline substance may be used as it is, or the alkaline substance may be used after being prepared into a solution. The basic substance may be mixed with the oxidizing agent and optionally the solvent and then fed into the fixed bed reactor, and the mixing may be performed either outside or inside the reactor, without particular limitation.
According to the process of the present invention, preferably the basic substance is pyridine.
According to the process of the present invention, the titanium silicalite is a generic term for a class of zeolites in which a portion of the silicon atoms in the lattice framework is replaced by titanium atoms, which can be represented by the formula xTiO2·SiO2And (4) showing. The content of titanium atoms in the titanium silicalite molecular sieve is not particularly limited in the invention, and can be selected conventionally in the field. Specifically, x may be 0.0001 to 0.05, preferably 0.01 to 0.03, more preferably 0.015 to 0.025.
The titanium silicalite molecular sieve in the first catalyst bed can be common titanium silicalite molecular sieves with various topological structures different from titanium silicalite molecular sieves, including all titanium silicalite molecular sieves except titanium silicalite molecular sieves, such as: the titanium silicalite molecular sieve may be selected from titanium silicalite molecular sieves of MFI structure (e.g., TS-1), titanium silicalite molecular sieves of MEL structure (e.g., TS-2), titanium silicalite molecular sieves of BEA structure (e.g., Ti-Beta), titanium silicalite molecular sieves of MWW structure (e.g., Ti-MCM-22), titanium silicalite molecular sieves of MOR structure (e.g., Ti-MOR), titanium silicalite molecular sieves of TUN structure (e.g., Ti-TUN), titanium silicalite molecular sieves of two-dimensional hexagonal structure (e.g., Ti-MCM-41, Ti-SBA-15), and titanium silicalite molecular sieves of other structures (e.g., Ti-ZSM-48), etc. The titanium silicalite molecular sieve in the second bed layer is preferably selected from a titanium silicalite molecular sieve with an MFI structure, a titanium silicalite molecular sieve with an MEL structure and a titanium silicalite molecular sieve with a BEA structure, more preferably is a titanium silicalite molecular sieve with an MFI structure, and is preferably TS-1.
The titanium silicon aluminum molecular sieve is a general term of a type of zeolite with titanium atoms and aluminum atoms replacing a part of silicon atoms in a lattice framework. The titanium silicalite molecular sieve can be common titanium silicalite molecular sieves with various topological structures, such as: the titanium-silicon-aluminum molecular sieve can be one or more of a titanium-silicon-aluminum molecular sieve with an MFI structure, a titanium-silicon-aluminum molecular sieve with an MEL structure, a titanium-silicon-aluminum molecular sieve with a BEA structure, a titanium-silicon-aluminum molecular sieve with an MWW structure, a titanium-silicon-aluminum molecular sieve with an MOR structure, a titanium-silicon-aluminum molecular sieve with a TUN structure, a titanium-silicon-aluminum molecular sieve with a two-dimensional hexagonal structure and titanium-silicon-aluminum molecular sieves with other structures. The titanium-silicon-aluminum molecular sieve is preferably one or more of a titanium-silicon-aluminum molecular sieve with an MFI structure, a titanium-silicon-aluminum molecular sieve with an MEL structure and a titanium-silicon-aluminum molecular sieve with a BEA structure, and more preferably a titanium-silicon-aluminum molecular sieve with an MFI structure.
According to the present invention, the object of the present invention can be achieved by using a titanium-silicon-aluminum molecular sieve as a catalyst, but the inventors of the present invention found in their research that a titanium-silicon-aluminum catalyst prepared by a specific method is particularly advantageous for improving the oxidant conversion rate and cyclohexanone selectivity.
Thus, according to a preferred embodiment a of the present invention, the titanium silicalite molecular sieve is prepared by the following method:
(1) Mixing and pulping a discharging agent and an organic acid solution, carrying out first heat treatment on the obtained slurry, and separating to obtain a first solid with the relative crystallinity of 70-90%, wherein the discharging agent is a discharging agent of a reaction device which takes a titanium silicalite molecular sieve as an active component of a catalyst;
(2) the first solid, the aluminum source, and optionally the titanium source, are mixed with the alkali source in the presence of an aqueous solvent prior to the second heat treatment. Wherein the titanium source is a selectively used component.
In a preferred embodiment a of the present invention, the discharging agent of the reaction apparatus using a titanium silicalite as the catalyst active component may be a discharging agent discharged from various apparatuses using a titanium silicalite as the catalyst active component, for example, a discharging agent discharged from an oxidation reaction apparatus using a titanium silicalite as the catalyst active component. The oxidation reaction may be various oxidation reactions, for example, the discharging agent of the reaction apparatus using the titanium silicalite molecular sieve as the active component of the catalyst may be one or more of a discharging agent of an ammoximation reaction apparatus, a discharging agent of a hydroxylation reaction apparatus and a discharging agent of an epoxidation reaction apparatus, specifically, one or more of a discharging agent of a cyclohexanone ammoximation reaction apparatus, a discharging agent of a phenol hydroxylation reaction apparatus and a discharging agent of an propene oximation reaction apparatus, and preferably, the discharging agent is a catalyst deactivated by reaction in an alkaline environment, and therefore, for the present invention, the discharging agent is preferably a discharging agent of a cyclohexanone ammoximation reaction apparatus (such as deactivated titanium silicalite TS-1, powdery molecular sieve having a particle size of 100-500 nm).
In a preferred embodiment A of the present invention, the discharging agent is a deactivated catalyst whose activity cannot be restored to 50% of the initial activity by a conventional regeneration method such as solvent washing or calcination (the initial activity refers to the average activity of the catalyst within 1h under the same reaction conditions; for example, in the actual cyclohexanone oximation reaction, the initial activity of the catalyst is generally 95% or more).
The activity of the discharging agent varies depending on its source. Generally, the activity of the discharging agent can be 5-95% of the activity of the titanium silicalite when fresh (i.e., the activity of the fresh agent). Preferably, the activity of the discharging agent can be less than 50% of the activity of the titanium silicalite molecular sieve in a fresh state, and more preferably, the activity of the discharging agent can be 10-40% of the activity of the titanium silicalite molecular sieve in a fresh state. The activity of the titanium silicalite molecular sieve freshener is generally more than 90%, and usually more than 95%.
In a preferred embodiment a of the invention, the discharging agent can be derived from an industrial deactivating agent or from a deactivated catalyst after the reaction in the laboratory. Certainly, from the perspective of preparation effect, the method of the present invention can also adopt a fresh molecular sieve such as a titanium-silicon molecular sieve as a raw material, which is not suitable from the perspective of cost control, etc., and the method provided by the present invention mainly uses a deactivated catalyst containing a titanium-silicon molecular sieve as a raw material, and changes waste into valuable, thereby saving cost.
In a preferred embodiment a of the present invention, the discharging agent of each apparatus is individually measured by the reaction of each apparatus, and the discharging agent of the present invention is obtained as long as it is ensured that the activity of the discharging agent is lower than that of the fresh catalyst under the same reaction conditions in the same apparatus. As mentioned before, the activity of the discharging agent is preferably less than 50% of the activity of the fresh catalyst.
In a preferred embodiment A of the present invention, taking the discharging agent of the cyclohexanone ammoximation reaction apparatus as an example, the activity is measured by the following method:
taking a TS-1 molecular sieve (prepared by the method described in Zeolite, 1992, Vol.12: 943-950), TiO22.1%) was placed in a 100mL slurry bed reactor with continuous feed and membrane separation means, and a mixture of water and 30 wt% hydrogen peroxide (water to hydrogen peroxide volume ratio of 10: 9) a mixture of cyclohexanone and tert-butanol was added at a rate of 10.5mL/h (the volume ratio of cyclohexanone to tert-butanol was 1: 2.5) adding 36 wt% ammonia water at the speed of 5.7mL/h, simultaneously adding the three material flows, continuously discharging at the corresponding speed, keeping the reaction temperature at 80 ℃, sampling the product every 1h after the reaction is stable, analyzing the composition of a liquid phase by using a gas chromatography, calculating the conversion rate of cyclohexanone by using the following formula, and taking the cyclohexanone as the activity of the titanium-silicon molecular sieve. Conversion ratio of cyclohexanone [ (molar amount of cyclohexanone charged-molar amount of unreacted cyclohexanone)/molar amount of cyclohexanone charged ]X 100%. Wherein the result of 1h is taken as the initial activity.
In a preferred embodiment a of the present invention, the step (2) is preferably performed as follows: and mixing an aluminum source and an alkali source in the presence of an aqueous solvent to obtain a mixed solution, and mixing the mixed solution with the first solid and the titanium source to perform the second heat treatment. Thus, the activity of the titanium-silicon-aluminum molecular sieve can be further improved.
In a preferred embodiment a of the present invention, the beating is preferably performed at normal temperature and normal pressure.
In the preferred embodiment a of the present invention, unless otherwise specified, the heat treatment is generally performed under autogenous pressure in the case of sealing.
In the preferred embodiment A of the present invention, the temperature of the first heat treatment is preferably 20 to 45 ℃ (e.g., 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃ or any value therebetween).
In a preferred embodiment a of the present invention, the time of the first heat treatment may be determined as needed, and in the present invention, the time of the first heat treatment is preferably 1 to 30 hours, preferably 1 to 24 hours, and more preferably 10 to 20 hours. The inventor of the invention finds that under the specific first heat treatment condition, the crystallinity can be more favorably controlled to meet the range, so that the titanium-silicon-aluminum molecular sieve with good catalytic performance is obtained.
In the preferred embodiment a of the present invention, the temperature of the second heat treatment is preferably 100-.
In the preferred embodiment a of the present invention, the time of the second heat treatment can be determined according to the need, and for the present invention, the time of the second heat treatment is preferably 0.5 to 25 hours, preferably 2 to 24 hours, and more preferably 5 to 20 hours.
In the preferred embodiment A of the present invention, the concentration of the organic acid solution is preferably >0.1mol/L, more preferably 1mol/L or more, and still more preferably 2 to 15 mol/L. In the invention, the main solvent of the acid solution is water, and other solvent auxiliaries can be added according to the requirement. The titanium-silicon-aluminum molecular sieve prepared in the way has better catalytic performance.
In preferred embodiment a of the present invention, the mass ratio of the discharging agent, the titanium source, the aluminum source, the organic acid, the alkali source, and the water is preferably 100: (0.1-10): (0.1-10): (0.005-50): (0.5-50): (20-1000), more preferably 100: (0.5-10): (0.5-10): (1-15): (1-20): (100-800), most preferably 100: (1-5): (0.5-2): (2-8): (5-15): (150-2Calculated as H, the organic acid+The alkali source is N or OH-And (6) counting. More preferably, the mass ratio of the discharging agent to the organic acid is 100: (2-8).
In a preferred embodiment a of the present invention, the titanium silicalite molecular sieve can be common titanium silicalite molecular sieve with various topologies, and can be the same as or different from the titanium silicalite molecular sieve in the first catalyst bed layer, such as: the titanium silicalite molecular sieve may be selected from one or more of a titanium silicalite molecular sieve of MFI structure (e.g., TS-1), a titanium silicalite molecular sieve of MEL structure (e.g., TS-2), a titanium silicalite molecular sieve of BEA structure (e.g., Ti-Beta), a titanium silicalite molecular sieve of MWW structure (e.g., Ti-MCM-22), a titanium silicalite molecular sieve of hexagonal structure (e.g., Ti-MCM-41, Ti-SBA-15), a titanium silicalite molecular sieve of MOR structure (e.g., Ti-MOR), a titanium silicalite molecular sieve of TUN structure (e.g., Ti-TUN), and a titanium silicalite molecular sieve of other structure (e.g., Ti-ZSM-48).
Preferably, the titanium silicalite molecular sieve is selected from one or more of a titanium silicalite molecular sieve of an MFI structure, a titanium silicalite molecular sieve of an MEL structure and a titanium silicalite molecular sieve of a BEA structure. More preferably, the titanium silicalite molecular sieve is a titanium silicalite molecular sieve of MFI structure, such as TS-1 molecular sieve.
In the preferred embodiment a of the present invention, the organic acid is not particularly limited, and may be an organic carboxylic acid of C1 to C10, preferably one or more of naphthenic acid, peroxyacetic acid and peroxypropionic acid. The inventor of the invention finds that the use of specific types and dosage of organic acid can be more beneficial to controlling the crystallinity to meet the range, thereby obtaining the titanium-silicon-aluminum molecular sieve with good catalytic performance.
In a preferred embodiment a of the present invention, the titanium source may be an organic titanium source (e.g., an organic titanate) and/or an inorganic titanium source (e.g., an inorganic titanium salt). Wherein the inorganic titanium source can be TiCl4、Ti(SO4)2、TiOCl2One or more of titanium hydroxide, titanium oxide, titanium nitrate, titanium phosphate and the like, and the organic titanium source can be one or more of fatty titanium alkoxide and organic titanate. The titanium source is preferably an organic titanium source, and is further preferably an organic titanate. The organic titanate is preferably of the formula M4TiO4Wherein M is preferably an alkyl group having 1 to 4 carbon atoms and 4M's may be the same or different, preferably the organotitanate is selected from the group consisting of isopropyltitanateOne or more of an ester, n-propyl titanate, tetrabutyl titanate, and tetraethyl titanate. Specific examples of the titanium source may be, but are not limited to: TiOCl2Titanium tetrachloride, titanium sulfate, tetrapropyl titanate (including various isomers of tetrapropyl titanate, such as tetraisopropyl titanate and tetran-propyl titanate), tetrabutyl titanate (various isomers of tetrabutyl titanate, such as tetran-butyl titanate), and tetraethyl titanate.
In the preferred embodiment a of the present invention, the alkali source can be an organic alkali source and/or an inorganic alkali source, wherein the inorganic alkali source can be ammonia or alkali whose cation is alkali metal or alkaline earth metal, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, barium hydroxide, etc., and the organic alkali source can be one or more of urea, aliphatic amine compound, aliphatic alcohol amine compound, and quaternary ammonium alkali compound.
In a preferred embodiment a of the present invention, the quaternary ammonium base may be various organic quaternary ammonium bases, and the aliphatic amine may be various NH3In which at least one hydrogen is substituted with an aliphatic hydrocarbon group (preferably an alkyl group), which may be a variety of NH3Wherein at least one hydrogen is substituted with a hydroxyl-containing aliphatic hydrocarbon group (preferably an alkyl group).
Specifically, the quaternary ammonium base may be a quaternary ammonium base represented by formula II, the aliphatic amine may be an aliphatic amine represented by formula III, and the aliphatic alcohol amine may be an aliphatic alcohol amine represented by formula IV:
Figure BDA0001576316490000141
in the formula II, R5、R6、R7And R8Each is C1-C4Alkyl of (2) including C1-C4Straight chain alkyl of (2) and C3-C4Branched alkyl groups of (a), for example: r5、R6、R7And R8Each may be methylEthyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl.
R9(NH2)nFormula III
In the formula III, n is an integer of 1 or 2. When n is 1, R9Is C1～C6Alkyl of (2) including C1～ C6Straight chain alkyl of (2) and C3-C6Such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl and n-hexyl. When n is 2, R 9Is C1-C6Alkylene of (2) including C1～C6Linear alkylene of (A) and (C)3～C6Such as methylene, ethylene, n-propylene, n-butylene, n-pentylene or n-hexylene. More preferably, the aliphatic amine compound is one or more of ethylamine, n-butylamine, butanediamine and hexamethylenediamine.
(HOR10)mNH(3-m)Formula IV
In the formula IV, m are R10Are the same or different and are each C1-C4Alkylene of (2) including C1-C4Linear alkylene of (A) and (C)3-C4Branched alkylene groups of (a), such as methylene, ethylene, n-propylene and n-butylene; m is 1, 2 or 3. More preferably, the aliphatic alcohol amine compound is one or more of monoethanolamine, diethanolamine and triethanolamine.
Most preferably, the alkali source is one or more of sodium hydroxide, ammonia, ethylenediamine, n-butylamine, butanediamine, hexamethylenediamine, monoethanolamine, diethanolamine, triethanolamine, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.
Wherein, when the alkali source contains ammonia water, the mol ratio of the alkali source includes NH in molecular form3And NH in ionic form4 +The presence of ammonia.
In a preferred embodiment a of the invention, the alkali source is preferably provided in the form of an alkali solution, more preferably an alkali solution having a pH > 9.
In a preferred embodiment a of the present invention, the aluminum source is a substance capable of providing aluminum, and preferably the aluminum source is one or more of aluminum sol, aluminum salt, aluminum hydroxide and alumina, and the aluminum sol is preferably contained in an amount of 10 to 50 wt% based on the alumina.
In a preferred embodiment a of the present invention, the aluminum salt may be an inorganic aluminum salt and/or an organic aluminum salt, the organic aluminum salt is preferably an organic aluminum salt having C1-C10, and the inorganic aluminum salt may be one or more of aluminum sulfate, sodium metaaluminate, aluminum chloride, and aluminum nitrate, for example.
In the preferred embodiment a of the present invention, the method of the present invention preferably further comprises a step of recovering a product from the heat-treated material of step (2), wherein the step of recovering the product is a conventional method, is familiar to those skilled in the art, and is not particularly required, and generally refers to a process of filtering, washing, drying and roasting the product. Wherein, the drying process can be carried out at the temperature of between 20 and 200 ℃, and the roasting process can be carried out at the temperature of between 300 and 800 ℃ in a nitrogen atmosphere for 0.5 to 6 hours and then in an air atmosphere for 3 to 12 hours.
The inventors of the present invention further found that if the deactivated silicon aluminum molecular sieve is used to contact with organic acid, etc., the titanium silicon aluminum molecular sieve with better cyclohexanone catalytic effect can be obtained, therefore, according to another preferred embodiment B of the present invention, the method for preparing the titanium silicon aluminum molecular sieve comprises:
(a) Mixing and pulping a discharging agent and an organic acid solution, carrying out first heat treatment on the obtained slurry, and separating to obtain a first solid with the relative crystallinity of 50-70%, wherein the discharging agent is a discharging agent of a reaction device which takes a silicon-aluminum molecular sieve as an active component of a catalyst;
(b) and mixing the first solid, the optional aluminum source, the titanium source and the alkali source in the presence of the aqueous solvent, and then carrying out a second heat treatment. Wherein the aluminum source is a component which is selectively used.
In a preferred embodiment B of the invention, the particular definition of the discharging agent is as defined above except that the titanium silicalite is replaced with a silicoaluminophosphate molecular sieve. The discharging agent of the reaction device using the aluminosilicate molecular sieve as the catalyst active component may be a discharging agent discharged from various devices using the aluminosilicate molecular sieve as the catalyst active component, for example, a discharging agent discharged from a synthesis reaction device using the aluminosilicate molecular sieve as the catalyst active component (such as a discharging agent of a synthesis reaction device of hydrogen sulfide and methanol), or a discharging agent discharged from a catalytic cracking reaction device using the aluminosilicate molecular sieve as the catalyst active component. For the present invention, the discharging agent is preferably the discharging agent of the synthesis reaction device of hydrogen sulfide and methanol (such as deactivated silicon-aluminum molecular sieve ZSM-5, powder, particle size of 100-500 nm).
As mentioned before, the activity of the discharging agent is preferably less than 50% of the activity of the fresh catalyst.
In a preferred embodiment B of the present invention, the activity is measured by taking as an example a discharging agent of a synthesis reaction apparatus for hydrogen sulfide and methanol:
ZSM-5 molecular sieve (prepared according to the method described in CN1235875A in comparative example 1) is treated with water vapor at 200 ℃ for 10h, then tabletted, sieved, and 20-40 mesh particles are filled into a tubular reaction tube with the diameter of 0.8cm and the length of 55cm, and the volume of a catalyst particle bed layer is 2cm3. The reaction temperature is 300 ℃, the reaction pressure is 1atm, the feeding molar ratio of hydrogen sulfide and methanol is 1:2, and the total gas volume space velocity is 700h-1Under the conditions of (1), a catalytic reaction for synthesizing dimethyl sulfide is carried out. Analyzing the composition of the product obtained after the catalytic reaction by using a gas chromatography every 1 hour, calculating the conversion rate of the methanol according to the analysis result, and taking the conversion rate as the activity of the silicon-aluminum molecular sieve. Conversion of methanol [ (molar amount of methanol added-molar amount of unreacted methanol)/molar amount of methanol added]X 100%. Wherein the result of 1h is taken as the initial activity.
In a preferred embodiment B of the present invention, the step (B) is preferably performed as follows: and mixing an aqueous solution containing an alkali source with the first solid and the titanium source, and then carrying out the second heat treatment.
In preferred embodiment B of the present invention, the temperature of the first heat treatment is preferably 50 to 150 ℃.
In the preferred embodiment B of the present invention, the time of the first heat treatment can be determined as needed, and in the present invention, the time of the first heat treatment is preferably 0.5 to 40 hours, preferably 1 to 24 hours, and more preferably 10 to 20 hours. The inventor of the invention finds that under the specific first heat treatment condition, the crystallinity can be more favorably controlled to meet the range, so that the titanium-silicon-aluminum molecular sieve with good catalytic performance is obtained.
In the preferred embodiment B of the present invention, the temperature of the second heat treatment is preferably 100-.
In the preferred embodiment B of the present invention, the time of the second heat treatment is preferably determined according to the need, and for the present invention, the time of the second heat treatment is preferably 0.5 to 25 hours, preferably 2 to 24 hours, and more preferably 5 to 20 hours.
In preferred embodiment B of the present invention, the mass ratio of the discharging agent, the titanium source, the organic acid, the alkali source and the water is preferably 100: (0.1-10): (0.005-50): (0.5-50): (20-1000), more preferably 100: (0.5-10): (1-15): (1-20): (100-800), most preferably 100: (1-5): (2-8): (5-15): (150-250). The discharging agent is SiO 2Calculated as H, the organic acid+The alkali source is N or OH-And (6) counting. More preferably, the mass ratio of the discharging agent to the organic acid is 100: (2-8).
In the preferred embodiment B of the present invention, the silicon-aluminum molecular sieve may be a common silicon-aluminum molecular sieve with various topologies, and preferably, the silicon-aluminum molecular sieve is at least one selected from a silicon-aluminum molecular sieve with MFI structure, a silicon-aluminum molecular sieve with MEL structure, and a silicon-aluminum molecular sieve with BEA structure. More preferably, the silicoaluminophosphate molecular sieve is a silicoaluminophosphate molecular sieve of the MFI structure, such as ZSM-5 molecular sieve.
The specific selection of the organic acid solution, the titanium source, the alkali source, and the like for the beating conditions may be the same as those in the preferred embodiment a (as described above), and will not be described again here.
As mentioned above, the present invention also relates to a process for preparing a titanium silicalite molecular sieve, as described in embodiment a or embodiment B. The prepared titanium-silicon-aluminum molecular sieve is beneficial to the diffusion of reactant and product molecules in a catalytic reaction, and is particularly beneficial to a catalytic oxidation reaction in which alcohol (such as tert-butyl alcohol or cyclohexanol) participates.
The present invention will be described in detail below by way of examples.
In the following examples and comparative examples, the reagents used were all commercially available chemically pure reagents.
In the following examples and comparative examples, the pressures were gauge pressures unless otherwise specified.
In the following examples and comparative examples, the composition of each component in the obtained reaction liquid was measured by gas chromatography, and quantified by the calibration normalization method, and on the basis of this, the oxidant conversion and cyclohexanone selectivity were calculated by the following formulas, respectively:
oxidant conversion (%) × 100 (moles of oxidant participating in the reaction/moles of oxidant added);
the effective oxidant utilization (%) (moles of cyclohexanone/moles of oxidant added) × 100;
cyclohexanone selectivity (%) × 100 (moles of cyclohexanone/moles of cyclohexanol consumed by the reaction).
In the following examples and comparative examples, the shaped catalysts used were prepared as follows: under the conditions of normal pressure and 60 ℃, adding an organic silicon compound ethyl orthosilicate into a tetrapropyl ammonium hydroxide aqueous solution, mixing, stirring and hydrolyzing for 5 hours to obtain a colloidal solution; adding a titanium silicalite molecular sieve or a titanium silicalite molecular sieve into the obtained colloidal solution, and uniformly mixing to obtain slurry, wherein the mass ratio of the titanium silicalite molecular sieve or the titanium silicalite molecular sieve, the organic silicide, the tetrapropylammonium hydroxide and the water is 100:25:5: 250; and (3) continuously stirring the slurry for 2 hours, and roasting after conventional spray granulation to obtain the microspherical catalyst used by the invention.
Preparation example 1
Preparation of titanium silicalite molecular sieves according to preferred embodiment A
(1) Taking a TS-1 molecular sieve (prepared by the method described in Zeolite, 1992, Vol.12: 943-950), TiO22.1%) was placed in a 100mL slurry bed reactor with continuous feed and membrane separation means, and a mixture of water and 30 wt% hydrogen peroxide (water to hydrogen peroxide volume ratio of 10: 9) a mixture of cyclohexanone and tert-butanol was added at a rate of 10.5mL/h (the volume ratio of cyclohexanone to tert-butanol was 1: 2.5) adding 36 wt% ammonia water at the speed of 5.7mL/h, simultaneously adding the three material flows, continuously discharging at the corresponding speed, maintaining the reaction temperature at 80 ℃, sampling the product every 1h after the reaction is stable, analyzing the composition of a liquid phase by using a gas chromatography, calculating the conversion rate of cyclohexanone by using the following formula, and taking the cyclohexanone as the activity of the titanium-silicon molecular sieve. Conversion of cyclohexanone [ (molar amount of cyclohexanone charged-molar amount of unreacted cyclohexanone)/molar amount of cyclohexanone charged]X 100%. The cyclohexanone conversion, measured for the first time, i.e. 1h, was its initial activity, which was 99.5%. After a period of 168 hours, the cyclohexanone conversion rate is reduced from the initial 99.5% to 50%, the catalyst is separated and regenerated by roasting (roasting at 570 ℃ for 4 hours in the air atmosphere), and then the catalyst is continuously used in the cyclohexanone ammoximation reaction, the step is repeatedly carried out until the activity after regeneration is lower than 50% of the initial activity, the inactivated ammoximation catalyst sample is used as the discharging agent of the invention, and then the discharging agents SH-1 (the activity is 40%), SH-2 (the activity is 25%) and SH-3 (the activity is 10%) are sequentially obtained according to the method.
(2) Under normal temperature (20 ℃, the same below) and normal pressure (0.1MPa, the same below), firstly mixing and pulping the inactivated cyclohexanone oximation catalyst SH-1 and 1mol/L naphthenic acid aqueous solution, and then mixing and stirring the mixed slurry at 45 ℃ for 12 hours; after solid-liquid separation, mixing a solid (with a relative crystallinity of 71 percent), aluminum source aluminum sulfate, titanium source titanium sulfate and a sodium hydroxide aqueous solution (with a pH value of 12), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 12 hours at 170 ℃, wherein the material comprises the following components in mass: a titanium source: an aluminum source: acid: alkali: 100 parts of water: 1: 1: 2: 5: 250, deactivated cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated as OH, base-And (6) counting. And filtering the obtained product, washing with water, drying at 110 ℃ for 120min, and then roasting at 550 ℃ for 3h to obtain the molecular sieve, wherein an XRD (X-ray diffraction) crystal phase diagram of the molecular sieve shows that the titanium-silicon-aluminum molecular sieve (TS-A) with an MFI structure is obtained.
(3) Firstly, mixing and pulping the inactivated cyclohexanone oximation catalyst SH-2 and 5mol/L peroxyacetic acid solution at normal temperature and normal pressure, and then mixing and stirring the mixed pulp at 20 ℃ for 20 hours; after solid-liquid separation, mixing a solid (the relative crystallinity is 89%), aluminum source aluminum sol (the content is 20 weight%), titanium source tetrabutyl titanate and tetrapropyl ammonium hydroxide aqueous solution (the pH is 10), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 20 hours at 150 ℃, wherein the material comprises the following components in mass: a titanium source: aluminum source: acid: alkali: 100 parts of water: 2: 0.5: 8: 15: 200 deactivated cyclohexanone oximation catalyst with SiO 2Measured as H, acid+Calculated as OH, base-And (6) counting. And (3) recovering the product according to the method in the step (2) to obtain the titanium-silicon-aluminum molecular sieve, wherein an XRD crystal phase diagram of the titanium-silicon-aluminum molecular sieve shows that the titanium-silicon-aluminum molecular sieve (TS-B) with an MFI structure is obtained.
(4) Under normal temperature and normal pressure, mixing and pulping the inactivated cyclohexanone oximation catalyst SH-3 and 8mol/L peroxypropionic acid aqueous solution, and then mixing and stirring the mixed pulp at 30 ℃ for 10 hours; after solid-liquid separation, mixing a solid (the relative crystallinity is 80%), aluminum source aluminum hydroxide, titanium source titanium tetrachloride and an ethylenediamine aqueous solution (the pH is 11), putting the mixed solution into a stainless steel sealed reaction kettle, and carrying out hydrothermal treatment for 5 hours at the temperature of 140 ℃, wherein the material comprises the following components in mass: a titanium source: an aluminum source: acid: alkali: 100 parts of water: 5: 2: 5: 5: 150 deactivated cyclohexanone oximation catalyst with SiO2Measured as H, acid+The base is calculated as N. And (3) recovering the product according to the method in the step (2) to obtain the titanium-silicon-aluminum molecular sieve, wherein an XRD crystal phase diagram of the titanium-silicon-aluminum molecular sieve shows that the titanium-silicon-aluminum molecular sieve (TS-C) with an MFI structure is obtained.
(5) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the mixed slurry is mixed at 60 ℃, the relative crystallinity of the solid after solid-liquid separation is 65%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (TS-D) with an MFI structure is obtained.
(6) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the mixed slurry is mixed at 180 ℃, the relative crystallinity of the solid after solid-liquid separation is 95%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (TS-E) with an MFI structure is obtained.
(7) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that formic acid is replaced by the peroxypropionic acid aqueous solution, the relative crystallinity of the solid after solid-liquid separation is 60%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (TS-F) with an MFI structure is obtained.
(8) Preparing a titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the deactivated cyclohexanone oximation catalyst: acid 100: 15, the relative crystallinity of the solid after solid-liquid separation is 62%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (TS-G) with an MFI structure is obtained.
(9) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the mixed slurry is mixed at 160 ℃, the peroxypropionic acid aqueous solution is replaced by acetic acid, and the inactivated cyclohexanone oximation catalyst: acid 100: 10, the relative crystallinity of the solid after solid-liquid separation is 55 percent, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (TS-H) with an MFI structure is obtained.
(10) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the TS-1 molecular sieve (the relative crystallinity is 100 percent), aluminum source aluminum hydroxide, titanium source titanium tetrachloride and ethylene diamine aqueous solution are directly mixed, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (TS-I) with an MFI structure is obtained.
Wherein the X-ray diffraction (XRD) phase diagram of the sample is determined on a Siemens D5005 type X-ray diffractometer, and the crystallinity of the sample relative to a reference sample is expressed by the ratio of the sum of diffraction intensities (peak heights) of five finger diffraction characteristic peaks between 22.5 degrees and 25.0 degrees in terms of 2 theta of the sample and the reference sample, wherein the crystallinity is 100 percent by taking a fresh TS-1 molecular sieve sample as the reference sample.
Preparation example 2
Preparation of titanium silicalite molecular sieves according to preferred embodiment B
(1) ZSM-5 molecular sieve (prepared according to the method described in CN1235875A in comparative example 1) is treated with water vapor at 200 ℃ for 10h, then tabletted, sieved, and 20-40 mesh particles are filled into a tubular reaction tube with the diameter of 0.8cm and the length of 55cm, and the bed volume of catalyst particles is 2.0cm3. At the reaction temperature of 300 ℃, the reaction pressure of 1atm, the feeding molar ratio of hydrogen sulfide and methanol of 1:2 and the total gas volume airspeed of 700h -1Under the conditions of (1), a catalytic reaction for synthesizing dimethyl sulfide is carried out. The composition of the product obtained after the catalytic reaction is analyzed by gas chromatography every 1 hour, and the conversion rate of the methanol is calculated according to the analysis result and is used as the activity of the silicon-aluminum molecular sieve. Conversion of methanol ═ [ (molar amount of methanol added-molar amount of unreacted methanol)/molar amount of methanol added]X 100%. Wherein the initial activity was 99% as the result of 1 h. After a period of about 180 hours, the conversion rate of methanol is reduced from the initial 99% to 50%, the catalyst is separated and regenerated by roasting (roasting at 570 ℃ for 4 hours in air atmosphere), then the catalyst is continuously used in the synthetic reaction of hydrogen sulfide and methanol, the step is repeatedly carried out until the activity after regeneration is lower than 50% of the initial activity, the inactivated catalyst sample is used as the discharging agent of the invention, and the discharging agents SH-I (the activity is 45%), SH-II (the activity is 35%) and SH-III (the activity is 15%) are obtained in sequence according to the method.
(2) Mixing and pulping the inactivated catalyst SH-I and 1mol/L naphthenic acid aqueous solution at normal temperature (20 ℃, the same below) and normal pressure (0.1MPa, the same below), and then mixing and stirring the mixed pulp at 50 ℃ for 12 hours; after solid-liquid separation, mixing the solid (the relative crystallinity is 70 percent), titanium sulfate as a titanium source and sodium hydroxide aqueous solution (the pH is 12), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 12 hours at the temperature of 170 ℃, wherein the material comprises the following components in mass percent: a titanium source: acid: alkali: 100 parts of water: 1: 2: 5: 250, deactivated catalyst is SiO 2Measured as H, acid+Calculated as OH, base-And (6) counting. Filtering the obtained product, washing with water, oven drying at 110 deg.C for 120min, and calcining at 550 deg.C for 3 hr to obtain molecular sieve with XRD crystal phase diagramA titanium silicalite molecular sieve (SA-a) with MFI structure is obtained.
(3) Mixing and pulping the inactivated catalyst SH-II and 5mol/L peroxyacetic acid solution at normal temperature and normal pressure, and then mixing and stirring the mixed pulp at 150 ℃ for 20 hours; after solid-liquid separation, mixing the solid (the relative crystallinity is 53 percent), titanium source tetrabutyl titanate and tetrapropyl ammonium hydroxide aqueous solution (the pH value is 10), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 20 hours at the temperature of 150 ℃, wherein the material comprises the following components in percentage by mass: a titanium source: acid: alkali: 100 parts of water: 2: 8: 15: 200, deactivated Cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated as OH, base-And (6) counting. And (3) recovering the product according to the method in the step (2) to obtain the titanium-silicon-aluminum molecular sieve, wherein an XRD crystal phase diagram of the titanium-silicon-aluminum molecular sieve shows that the titanium-silicon-aluminum molecular sieve (SA-B) with an MFI structure is obtained.
(4) Mixing and pulping the inactivated catalyst SH-III and 8mol/L aqueous solution of peroxypropionic acid at normal temperature and normal pressure, and then mixing and stirring the mixed pulp at 100 ℃ for 10 hours; after solid-liquid separation, mixing a solid (with relative crystallinity of 61 percent), titanium tetrachloride as a titanium source and an ethylenediamine aqueous solution (with pH of 11), putting the mixed solution into a stainless steel sealed reaction kettle, and performing hydrothermal treatment for 5 hours at 140 ℃, wherein the material comprises the following components in mass: a titanium source: acid: alkali: 100 parts of water: 5: 5: 5: 150, deactivated catalyst with SiO 2Measured as H, acid+The base is calculated as N. And (3) recovering the product according to the method in the step (2) to obtain the titanium-silicon-aluminum molecular sieve, wherein an XRD crystal phase diagram of the titanium-silicon-aluminum molecular sieve shows that the titanium-silicon-aluminum molecular sieve (SA-C) with an MFI structure is obtained.
(5) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the mixed slurry is mixed at 40 ℃, the relative crystallinity of the solid after solid-liquid separation is 41 percent, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (SA-D) with an MFI structure is obtained.
(6) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the mixed slurry is mixed at 180 ℃, the relative crystallinity of the solid after solid-liquid separation is 80%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (SA-E) with an MFI structure is obtained.
(7) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that formic acid is replaced by the peroxypropionic acid aqueous solution, the relative crystallinity of the solid after solid-liquid separation is 38%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (SA-F) with an MFI structure is obtained.
(8) Preparing a titanium-silicon-aluminum molecular sieve according to the method in the step (4), wherein the difference is that the deactivated catalyst: acid 100: 15, the relative crystallinity of the solid after solid-liquid separation is 40%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (SA-G) with an MFI structure is obtained.
(9) Preparing a titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that the mixed slurry is mixed at 160 ℃, the aqueous solution of the peroxopropionic acid is replaced by acetic acid, and the deactivated catalyst: acid 100: 10, the relative crystallinity of the solid after solid-liquid separation is 30%, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (SA-H) with an MFI structure is obtained.
(10) Preparing the titanium-silicon-aluminum molecular sieve according to the method in the step (4), except that a ZSM-5 molecular sieve (the relative crystallinity is 100 percent), titanium tetrachloride serving as a titanium source and an ethylene diamine aqueous solution are directly mixed, and an XRD crystal phase diagram shows that the titanium-silicon-aluminum molecular sieve (SA-I) with an MFI structure is obtained.
Wherein the X-ray diffraction (XRD) phase diagram of the sample is determined on a Siemens D5005 type X-ray diffractometer, and the crystallinity of the sample relative to a reference sample is expressed by the ratio of the sum of diffraction intensities (peak heights) of five finger diffraction characteristic peaks between 22.5 degrees and 25.0 degrees in terms of 2 theta of the sample and the reference sample, wherein the crystallinity is 100 percent by taking a fresh ZSM-5 molecular sieve sample as the reference sample.
Example 1
The reaction is carried out in two serially connected miniature fixed bed reactors, wherein each reactor is filled with a catalyst bed with a circular cross section and an equal diameter, and the ratio of the inner diameter of a first catalyst bed in the first reactor at the upstream to the inner diameter of a second catalyst bed in the second reactor at the downstream is 2: 1, filling a formed titanium silicon molecular sieve TS-1 (volume average particle size) in a first catalyst bed layer A 500 μm spherical catalyst having a density of 0.76g/cm3) And filling A formed titanium-silicon-aluminum molecular sieve TS-A in the second catalyst bed layer, wherein the weight ratio of the titanium-silicon molecular sieve to the titanium-silicon-aluminum molecular sieve is 6: 1.
cyclohexanol, hydrogen peroxide (provided as 30 wt% hydrogen peroxide) as an oxidant and methanol as a solvent were fed from the bottom of the first reactor, passed through the first catalyst bed to contact the formed titanium silicalite molecular sieves loaded therein (superficial velocity v)1Is 6 kg/(m)2S) residence time of 0.28 h); the liquid mixture from the first reactor is then continuously fed into a second reactor where it passes through a second catalyst bed to contact the formed TiSiAluminous molecular sieve (superficial velocity v)2Is 15 kg/(m)2S) with a residence time of 0.32 h).
Wherein the molar ratio of cyclohexanol to hydrogen peroxide is 1.2: 1, the pH values in the first reactor and the second reactor are both 6.8, the pH value regulator is ammonia water (the concentration is 25 weight percent), and the weight ratio of the solvent to the cyclohexanol is 15: 1; controlling the temperature in the first catalyst bed layer and the second catalyst bed layer to be 60 ℃ and 55 ℃ respectively, and controlling the pressure in the first reactor and the second reactor to be 1.5MPa respectively; the total amount of the molecular sieves in the first catalyst bed layer and the second catalyst bed layer is taken as a reference, and the weight space velocity of cyclohexanol is 5h -1。
Continuously monitoring the composition of the reaction mixture discharged from the reactor during the course of the reaction, the selective S in cyclohexanonetSelectivity S with initial (sample taken up to 0.5 hours after reaction) cyclohexanone0Ratio S oft/S0S is not less than 0.85t/S0<When 0.9 (namely, when the condition 1 is met), the mass content of the hydrogen peroxide in the liquid mixture is increased by 0.02-5%/day (the hydrogen peroxide concentration in the hydrogen peroxide is increased only by increasing the consumption of the hydrogen peroxide, and the consumption of the hydrogen peroxide is kept unchanged) until the cyclohexanone selectivity S' and the initial cyclohexanone selectivity S are obtained0Ratio S'/S of0S'/S is more than or equal to 0.90When the mass content is less than or equal to 1 (namely, when the condition 2 is met), the mass content of the oxidant is stopped to be improved.
The continuous operation was carried out under the above-mentioned conditions, during which the composition of the reaction mixture withdrawn from the second reactor was examined and the oxidant conversion and cyclohexanone selectivity were calculated, wherein the results at reaction times of 2 hours and 720 hours are shown in Table 1.
Comparative example 1
Cyclohexanone was prepared by oxidation of cyclohexanol in the same manner as in example 1, except that the formed titanium silicalite molecular sieve in the second catalyst bed was replaced with the same amount of formed titanium silicalite molecular sieve TS-1.
The results at reaction times of 2 hours and 720 hours are listed in table 1.
Comparative example 2
Cyclohexanone was prepared by oxidation of cyclohexanol in the same manner as in example 1, except that the formed titanium silicalite molecular sieve in the first catalyst bed was replaced with an equivalent amount of formed titanium silicalite molecular sieve TS-A.
The results at reaction times of 2 hours and 720 hours are listed in table 1.
Comparative example 3
Cyclohexanone was prepared by oxidation of cyclohexanol in the same manner as in example 1, except that the formed titanium silicalite molecular sieve in the first catalyst bed was replaced with the same amount of formed titanium silicalite molecular sieve TS-A and the formed titanium silicalite molecular sieve in the second catalyst bed was replaced with the same amount of formed titanium silicalite molecular sieve TS-1.
The results at reaction times of 2 hours and 720 hours are listed in table 1.
Comparative example 4
Cyclohexanone was prepared by oxidation of cyclohexanol in the same manner as in example 1, except that the formed titanosilicate molecular sieve in the second catalyst bed was replaced with an equivalent amount of formed titanosilicate molecular sieve ZSM-5.
The results at reaction times of 2 hours and 720 hours are listed in table 1.
Comparative example 5
Cyclohexanone was prepared by oxidation of cyclohexanol using the same procedure as in example 1, except that the formed titanium silicalite molecular sieve in the second catalyst bed was replaced with an equivalent amount of formed hollow titanium silicalite molecular sieve (the hollow titanium silicalite molecular sieve used was a hollow titanium silicalite molecular sieve sold under the designation HTS, available from changable petrochemical company ltd, han, hu, the titanium oxide content was 2.5 wt%, the same applies hereinafter).
The results at reaction times of 2 hours and 720 hours are listed in table 1.
Comparative example 6
Cyclohexanone was prepared by oxidation of cyclohexanol in the same manner as in example 1, except that the formed titanium silicalite molecular sieves in the first catalyst bed were replaced with formed hollow titanium silicalite molecular sieves of the same amount.
The results at reaction times of 2 hours and 720 hours are listed in table 1.
Example 2
The reaction is carried out in two serially connected mini-sized fixed bed reactors, wherein each reactor is filled with a catalyst bed with a circular cross section and an equal diameter, and the ratio of the inner diameter of the first catalyst bed in the first reactor at the upstream to the inner diameter of the second catalyst bed in the second reactor at the downstream is 6: 1, the first catalyst bed is filled with a shaped titanium silicalite Ti-MCM-41 (prepared as described by Corma et al, chem. Commun., 1994, 147-3) And filling a formed titanium-silicon-aluminum molecular sieve TS-B in the second catalyst bed layer, wherein the weight ratio of the titanium-silicon molecular sieve to the titanium-silicon-aluminum molecular sieve is 10: 1.
Cyclohexanol, hydrogen peroxide (provided as 30 wt% hydrogen peroxide) as an oxidant and methanol as a solvent were fed from the bottom of the first reactor, passed through the first catalyst bed to contact the formed titanium silicalite molecular sieves loaded therein (superficial velocity v)1Is 4 kg/(m)2S) with a residence time of 0.3 h); the liquid mixture from the first reactor is then continuously fed into a second reactor where it passes through a second catalyst bed to contact the formed titanium silicalite molecular sieves packed therein (superficial velocity v)2Is 26 kg/(m)2S), residence time 0.05 h).
Wherein the molar ratio of cyclohexanol to hydrogen peroxide is 4: 1, the pH values in the first reactor and the second reactor are both 7.2, the pH value regulator is pyridine aqueous solution (the concentration is 25 weight percent), and the weight ratio of the solvent to the cyclohexanol is 1: 1; controlling the temperature in the first catalyst bed layer and the second catalyst bed layer to 65 ℃ and 50 ℃ respectively, and controlling the pressure in the first reactor and the second reactor to 0.5MPa respectively; based on the total amount of the molecular sieves in the first catalyst bed layer and the second catalyst bed layer, the weight space velocity of cyclohexanol is 6h-1。
Continuously monitoring the composition of the reaction mixture discharged from the reactor during the course of the reaction, the selective S in cyclohexanone tSelectivity S with initial (sample taken up to 0.5 hours after reaction) cyclohexanone0Ratio S oft/S0S is not less than 0.85t/S0<When 0.9 (namely, when the condition 1 is met), the mass content of the hydrogen peroxide in the liquid mixture is increased by 0.02-5%/day (the hydrogen peroxide concentration in the hydrogen peroxide is increased only by increasing the consumption of the hydrogen peroxide, and the consumption of the hydrogen peroxide is kept unchanged) until the cyclohexanone selectivity S' and the initial cyclohexanone selectivity S are obtained0Ratio S'/S of0S'/S is more than or equal to 0.90When the mass content is less than or equal to 1 (namely, when the condition 2 is met), the mass content of the oxidant is stopped to be improved.
The continuous operation was carried out under the above-mentioned conditions, during which the composition of the reaction mixture withdrawn from the second reactor was examined and the oxidant conversion and cyclohexanone selectivity were calculated, wherein the results at reaction times of 2 hours and 720 hours are shown in Table 1.
Example 3
Cyclohexanone was prepared by oxidation of cyclohexanol in the same manner as in example 1, except that the formed titanosilicate molecular sieve in the second catalyst bed was replaced with an equivalent amount of formed titanosilicate molecular sieve TS-C.
The results at reaction times of 2 hours and 720 hours are listed in table 1.
Examples 4 to 9
Cyclohexanone was prepared by oxidation of cyclohexanol according to the procedure in example 3, except that the formed TiSiAl molecular sieves in the second catalyst bed were replaced with formed TiSiAl molecular sieves TS-D, TS-E, TS-F, TS-G, TS-H and TS-I, respectively, and the results for 2 hours and 720 hours are shown in Table 1.
Example 10
Cyclohexanone was prepared by oxidizing cyclohexanol to prepare cyclohexanone according to the method of example 1, except that the formed titanium silicalite molecular sieve in the second catalyst bed layer was replaced with formed titanium silicalite molecular sieve SA-a, and the results of the reaction for 2 hours and 720 hours are shown in table 1.
Example 11
Cyclohexanone was prepared by oxidizing cyclohexanol to prepare cyclohexanone according to the method of example 2, except that the formed titanium silicalite molecular sieve in the second catalyst bed layer was replaced with formed titanium silicalite molecular sieve SA-B, and the results of the reaction for 2 hours and 720 hours are shown in table 1.
Example 12
Cyclohexanone was prepared by oxidizing cyclohexanol to prepare cyclohexanone according to the method of example 3, except that the formed titanium silicalite molecular sieve in the second catalyst bed layer was replaced with formed titanium silicalite molecular sieve SA-C, and the results of the reaction for 2 hours and 720 hours are shown in table 1.
Examples 13 to 18
Cyclohexanone was prepared by oxidation of cyclohexanol according to the procedure of example 3, except that the formed TiSiAl molecular sieves in the second catalyst bed were replaced with formed TiSiAl molecular sieves SA-D, SA-E, SA-F, SA-G, SA-H and SA-I, respectively, and the results for 2 hours and 720 hours are shown in Table 1.
Example 19
Cyclohexanone was prepared by oxidation of cyclohexanol according to example 1, except that the ti-sial molecular sieve prepared in example 1 of CN102616805A was used as the source of the shaped ti-sial molecular sieve in the second catalyst bed, and the results for 2 hours and 720 hours are shown in table 1.
Example 20
Cyclohexanone was prepared by oxidizing cyclohexanol according to the method of example 1, except that the temperatures in the first catalyst bed and the second catalyst bed were controlled to 60 c, and the results of the reaction for 2 hours and 720 hours were shown in table 1, respectively.
Example 21
Cyclohexanone was prepared by oxidizing cyclohexanol according to the method of example 1, except that the temperatures in the first catalyst bed and the second catalyst bed were controlled to 55 c, 60 c, and the results of the reaction for 2 hours and 720 hours were shown in table 1, respectively.
Example 22
Cyclohexanone was prepared by oxidizing cyclohexanol according to the method of example 1, except that the temperatures in the first catalyst bed and the second catalyst bed were controlled to 90 c, 55 c, and the results of the reaction for 2 hours and 720 hours were shown in table 1, respectively.
TABLE 1
Figure BDA0001576316490000291
The above results confirm that the method of the present invention using titanium silicalite and titanium silicalite as catalysts for preparing cyclohexanone from cyclohexanol can achieve high oxidant conversion and cyclohexanone selectivity even if the reaction is carried out under mild reaction conditions (low energy consumption).
From the results of examples 3 and 4 to 9 (or examples 12 and 13 to 18), it can be seen that the titanium silicalite molecular sieves obtained by treating the discharging agent to a specific crystallinity and then heat treating with other raw materials according to the preferred embodiment can further improve the oxidant conversion and cyclohexanone selectivity. Furthermore, it can be seen from the results of comparative examples 1, 10 and 19 that the titanium silicalite molecular sieves prepared according to the preferred embodiment of the present invention have better catalytic performance.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be considered as the disclosure of the invention, and all fall within the scope of the invention.

Claims (17)

1. A method of preparing cyclohexanone, the method comprising: flowing a liquid mixture comprising cyclohexanol and an oxidant through a catalyst bed under oxidation reaction conditions; the catalyst bed layer comprises a first catalyst bed layer and a second catalyst bed layer, and the first catalyst bed layer is positioned at the upstream of the second catalyst bed layer by taking the flowing direction of the liquid mixture as a reference;
wherein the first catalyst bed layer is filled with a titanium-silicon molecular sieve; the second catalyst bed layer is filled with a titanium-silicon-aluminum molecular sieve;
the residence time of the liquid mixture in the first catalyst bed is T1The total residence time in the catalyst bed is T, T1/T=0.3-0.95；
The conditions under which the liquid mixture flows through the first catalyst bed and the second catalyst bed each include: the temperature is 0-80 ℃; the pressure is 0.1-3MPa in gage pressure.
2. The method of claim 1, wherein the weight ratio of the titanium silicalite molecular sieves packed in the first catalyst bed to the titanium silicalite molecular sieves packed in the second catalyst bed is 0.1-20: 1.
3. the method of claim 1, wherein the weight ratio of the titanium silicalite molecular sieves packed in the first catalyst bed to the titanium silicalite molecular sieves packed in the second catalyst bed is 0.2-10: 1.
4. the process of claim 1 or 2, wherein the superficial velocity of the liquid mixture flowing through the first catalyst bed is v1Superficial velocity through the second catalyst bed is v2，v1＜v2。
5. The process of claim 1 or 2, wherein the superficial velocity of the liquid mixture flowing through the first catalyst bed is v1Flows through the firstThe superficial velocity of the two catalyst beds is v2，v2/v1＝1-10。
6. The method of claim 4, wherein v2/v1＝2.5-8。
7. The method of claim 1 or 2, wherein T1/T=0.45-0.86。
8. The process of claim 1 or 2, wherein the temperature of the first catalyst bed is higher than the temperature of the second catalyst bed.
9. The process of claim 8, wherein the temperature of the first catalyst bed is 4-30 ℃ higher than the temperature of the second catalyst bed.
10. The method of claim 1 or 2, wherein the oxidizing agent is a peroxide.
11. A process according to claim 1 or 2, wherein the molar ratio of cyclohexanol to oxidant is from 0.1 to 20: 1.
12. a process according to claim 1 or 2, wherein the molar ratio of cyclohexanol to oxidant is from 0.2 to 10: 1.
13. the process of claim 1 or 2, wherein the weight space velocity of cyclohexanol is from 0.1 to 50h, based on the total amount of molecular sieve in the first and second catalyst beds-1。
14. The method of claim 1, wherein the method further comprises the step of preparing the titanium silicalite molecular sieve comprising:
(1) mixing and pulping a discharging agent and an organic acid solution, carrying out first heat treatment on the obtained slurry, and separating to obtain a first solid with the relative crystallinity of 70-90%, wherein the discharging agent is a discharging agent of a reaction device which takes a titanium silicalite molecular sieve as an active component of a catalyst;
(2) the first solid, the aluminum source, and optionally the titanium source, are mixed with the alkali source in the presence of an aqueous solvent prior to the second heat treatment.
15. The method of claim 14, wherein the discharging agent of the reaction device with the titanium silicalite molecular sieve as the catalyst active component is a discharging agent of an ammoximation reaction device;
And/or, the step (2) is carried out according to the following steps: mixing an aluminum source and an alkali source in the presence of an aqueous solvent to obtain a mixed solution, and performing the second heat treatment after mixing the mixed solution with the first solid and the titanium source;
and/or the temperature of the first heat treatment is 20-45 ℃; the temperature of the second heat treatment is 100-200 ℃;
and/or the time of the first heat treatment is 1-30 h; the time of the second heat treatment is 0.5-25 h;
and/or the concentration of the organic acid solution>0.1 mol/L; discharging agent: a titanium source: an aluminum source: organic acid: alkali source: the mass ratio of water is 100: 0.1-10: 0.1-10: 0.005-50: 0.5-50: 20-1000, the discharging agent is SiO2Calculated as H, the organic acid+The alkali source is N or OH-Counting;
and/or the titanium silicalite molecular sieve is a titanium silicalite molecular sieve with an MFI structure, and the activity of the discharging agent is less than 50% of the activity of the catalyst in a fresh state;
and/or the organic acid is one or more of naphthenic acid, peracetic acid and propionic acid; the alkali source is one or more of ammonia, aliphatic amine, aliphatic alcohol amine and quaternary ammonium hydroxide; the aluminum source is one or more of aluminum sol, aluminum salt, aluminum hydroxide and aluminum oxide; the titanium source is selected from inorganic titanium salt and/or organic titanate.
16. The method of claim 1, wherein the method further comprises the step of preparing the titanium silicalite molecular sieve comprising:
(a) mixing and pulping a discharging agent and an organic acid solution, carrying out first heat treatment on the obtained slurry, and separating to obtain a first solid with the relative crystallinity of 50-70%, wherein the discharging agent is a discharging agent of a reaction device which takes a silicon-aluminum molecular sieve as an active component of a catalyst;
(b) and mixing the first solid, the optional aluminum source, the titanium source and the alkali source in the presence of the aqueous solvent, and then carrying out a second heat treatment.
17. The method of claim 16, wherein the discharging agent of the reaction device with the silicon-aluminum molecular sieve as the catalyst active component is a discharging agent of a synthesis reaction device of hydrogen sulfide and methanol;
and/or, step (b) is carried out as follows: mixing an aqueous solution containing an alkali source with the first solid and the titanium source, and then carrying out the second heat treatment;
and/or the temperature of the first heat treatment is 50-150 ℃; the temperature of the second heat treatment is 100-200 ℃;
and/or the time of the first heat treatment is 0.5-40 h; the time of the second heat treatment is 0.5-25 h;
and/or the concentration of the organic acid solution >0.1 mol/L; discharging agent: a titanium source: organic acid: alkali source: the mass ratio of water is 100: 0.1-10: 0.005-50: 0.5-50: 20-1000, the discharging agent is SiO2Calculated as H, the organic acid+The alkali source is N or OH-Counting;
and/or the silicon-aluminum molecular sieve is a silicon-aluminum molecular sieve with an MFI structure, and the activity of the discharging agent is less than 50% of the activity of the catalyst in a fresh state;
and/or the organic acid is one or more of naphthenic acid, peracetic acid and propionic acid; the alkali source is one or more of ammonia, aliphatic amine, aliphatic alcohol amine and quaternary ammonium hydroxide; the aluminum source is one or more of aluminum sol, aluminum salt, aluminum hydroxide and aluminum oxide; the titanium source is selected from inorganic titanium salt and/or organic titanate.
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