CN107303499B

CN107303499B - Preparation method and application of paraffin hydrocarbon shape-selective isomerization catalyst

Info

Publication number: CN107303499B
Application number: CN201610252525.3A
Authority: CN
Inventors: 徐会青; 刘全杰; 贾立明; 王伟
Original assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Current assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Priority date: 2016-04-21
Filing date: 2016-04-21
Publication date: 2020-05-19
Anticipated expiration: 2036-04-21
Also published as: CN107303499A

Abstract

The invention relates to a preparation method and application of a paraffin hydrocarbon shape-selective isomerization catalyst. The method comprises the following steps: (1) filling a catalyst precursor containing amorphous silica-alumina, ZSM-23 molecular sieve raw powder and an active metal component into a fixed bed reactor; (2) introducing an aqueous solution containing diamine compounds and halogenated hydrocarbons, carrying out contact reaction with a catalyst precursor, and introducing oxygen-containing gas for treatment; (4) and introducing gas containing hydrogen for activation treatment to obtain the catalyst. The molecular sieve formed on the surface of the molecular sieve catalyst prepared by the method is uniformly distributed, the utilization rate of the molecular sieve is improved, the product diffusion is facilitated, and the reaction selectivity and activity are improved.

Description

Preparation method and application of paraffin hydrocarbon shape-selective isomerization catalyst

Technical Field

The invention relates to a preparation method and application of a paraffin hydrocarbon shape-selective isomerization catalyst.

Background

The zeolite molecular sieve material has special shape-selective catalytic performance due to uniform composition, regular structure, adjustable surface acidity and pore canal size of molecular size, and is widely applied to the fields of petroleum and natural gas processing, fine chemical engineering, environmental protection and nuclear waste treatment as a catalytic material, a gas separation and adsorbent, an ion exchanger and the like. The molecular sieve catalytic function is also developed from simple acid catalysis to alkali catalysis, acid-base dual-function catalysis, oxidation-reduction catalysis, metal catalysis and the like. The basis of molecular sieve catalytic functionalization and application field expansion is the development of new molecular sieve materials. The synthesis of zeolite molecular sieves is of great importance, and the artificial design of the structure of zeolite molecular sieves as required has become an effort.

In the seventies of the twentieth century, organic amine is used as a template agent in the synthesis of the molecular sieve to obtain the novel high-silicon three-dimensional cross pore passage molecular sieve represented by ZSM-5. The successful synthesis of the eighties aluminum phosphate series molecular sieves breaks the limit that the constituent elements of the molecular sieves are only limited to silicon and aluminum, and a large number of heteroatom molecular sieves appear. The two important breakthroughs lay the foundation for the synthesis of a large number of novel molecular sieve materials with unique pore channel structures and surface properties. The synthesis method of the molecular sieve is developed from the traditional hydrothermal synthesis method to various methods such as non-aqueous system synthesis, gas-solid phase synthesis, high-pressure synthesis, supercritical condition synthesis, weightlessness condition synthesis and the like, and the novel molecular sieve material is continuously developed. According to the statistics of international molecular sieve society (IZA) in 2003, the total number of structures of the molecular sieve reaches 145.

ZSM-22 molecular sieve and ZSM-23 molecular sieve are two kinds of novel high-silicon aluminum zeolite molecular sieves synthesized by people. There have been many reports on the synthesis methods of ZSM-22 molecular sieves and ZSM-23 molecular sieves. US4076842, US4528171 disclose a process for synthesizing ZSM-23 molecular sieves using pyrrolidine as a template. US6475464 discloses a process for synthesizing ZSM-23 molecular sieves using ZSM-23 seed crystals. US4556477 discloses a method for synthesizing a ZSM-22 molecular sieve with diethylamine hydrochloride as a template. US4902406, US5707600, US5783168 disclose the synthesis of ZSM-22 molecular sieves using 1, 6-hexanediamine as a template.

ZSM-22 molecular sieve belongs to the TON topology, has a ten-membered ring one-dimensional channel structure with an aperture size of 4.4X 5.5A, and belongs to the TON topology together with ZSM-22 molecular sieve having KZ-2, NU-10, Theta-1, ISI-1, ZSM-23 molecular sieve belonging to the MTT topology with a ten-membered ring one-dimensional channel structure with an aperture size of 4.5X 5.2, and belongs to the MTT topology together with ZSM-23 molecular sieve having KZ-1, ISI-4, SSZ-32. owing to the most suitable channel structure and stronger surface acid properties, these two molecular sieves show a high catalytic activity and selectivity in olefin and alkane isomerization reactions, have the advantage over other catalysts, have a good application prospect.

Although some synthesis of catalytic materials related to composite molecular sieves are disclosed at present, in particular, patent CN200510066974 relates to a preparation method of a ZSM-23/ZSM-22 composite molecular sieve, and a ZSM-23/ZSM-22 composite molecular sieve catalyst prepared by the method has an acid center with moderate strength and a pore structure matched with a wax molecule, has obvious spatial limitation on multi-branched isomers, and can enable paraffin to generate isomerization reaction to a certain extent, in the preparation process of the catalyst, most of the acid center is covered, so that the obtained catalyst has weak acidity and low activity and selectivity.

The synthesis of ZSM-22 molecular sieve and ZSM-23 molecular sieve is carried out by taking organic amine as structure directing agent and crystallizing at certain temperature for certain time under alkaline environment. In the synthesis process, a large amount of industrial wastewater containing organic amine, alkali and the like is generated, and the harmless treatment is difficult to carry out, so that the production cost of the molecular sieve is greatly increased, the serious environmental pollution is caused, and the use of the molecular sieve is greatly limited.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a preparation method and application of a paraffin hydrocarbon shape-selective isomerization catalyst. The composite molecular sieve of the invention is different from a combined molecular sieve of simply and physically mixed ZSM-22 molecular sieves and ZSM-23 molecular sieves, and the method is characterized in that the ZSM-22 molecular sieves and the ZSM-23 molecular sieves of different types are formed on the surface of a catalyst precursor. The composite molecular sieve has the pore channel structure characteristics and the acidic characteristics of the ZSM-22 molecular sieve and the ZSM-23 molecular sieve, the synergistic effect between the ZSM-22 molecular sieve and the ZSM-23 molecular sieve can be more effectively exerted, and a good synergistic effect is embodied, so that the unique catalytic performance is embodied.

The preparation method of the paraffin hydrocarbon shape-selective isomerization catalyst comprises the following steps: (1) filling a catalyst precursor containing amorphous silica-alumina, ZSM-23 molecular sieve raw powder and an active metal component into a fixed bed reactor; (2) introducing an aqueous solution containing diamine compounds and halogenated hydrocarbons, carrying out contact reaction with a catalyst precursor, and then introducing oxygen-containing gas for treatment; (3) introducing an ammonium nitrate aqueous solution to contact and react with the catalyst precursor treated in the step (2), and then introducing nitrogen or inert gas to treat; (4) and introducing gas containing hydrogen for activation treatment to obtain the paraffin hydrocarbon shape-selective isomerization catalyst.

In the method of the present invention, the catalyst precursor described in step (1) has the following properties: the amorphous silicon-aluminum SiO₂And Al₂O₃The molar ratio of (A) to (B) is 5 to 200, preferably 10 to 100; the content of the ZSM-23 molecular sieve raw powder (based on the mass of the catalyst precursor, the same below) is 1-50% (mass percent, the same below), and preferably 5-40%. The active metal component is platinum or/and palladium, and the content of the active component is 0.1-10% by metal based on the total weight of the final catalyst. Preferably 0.1% to 2%, more preferably 0.2% to 1.0%.

In the method of the present invention, the preparation method of the catalyst precursor described in step (1) can be prepared according to the prior art, and the general process is as follows: the preparation method comprises the steps of fully mixing aluminum hydroxide dry glue powder, white carbon black and sesbania powder, then adding a peptizer (sodium hydroxide solution), kneading into a plastic paste, extruding into strips for molding, drying, roasting, then loading active metal components, and drying and roasting to obtain the catalyst precursor. Specific preparation conditions can be determined according to conventional knowledge in the art.

In the method of the present invention, the diamine compound in the step (2) has a carbon atom number of C₅~C₈The diamine of (b) is preferably one or more of hexamethylenediamine, octamethylenediamine and heptamethylenediamine.

In the method, the halogenated hydrocarbon in the step (2) is a halogenated hydrocarbon containing 1-3 carbon atoms, preferably CH₃I、CH₃CHCl₂Or CHCl₃In (1)One or more of them.

In the method, the concentration of the halogenated hydrocarbon in the step (2) in the aqueous solution containing the diamine compound and the halogenated hydrocarbon is 0.01-2 mol/L, preferably 0.1-1 mol/L.

In the method of the present invention, the molar ratio of the diamine compound and the halide in the step (2) is 0.5 to 5, preferably 1 to 3.

In the method, the ratio of the feeding amount of the aqueous solution containing the diamine compound and the halogenated hydrocarbon in the step (2) to the volume of the catalyst is 0.1-10, preferably 0.5-5; the contact reaction conditions are as follows: the reaction pressure is 0.2-10 MPa, preferably 0.5-5 MPa, the reaction temperature is 150-220 ℃, preferably 170-200 ℃, and the reaction time is 12-100 hours, preferably 24-72 hours.

In the method, the temperature for introducing the oxygen-containing gas for treatment in the step (2) is 400-600 ℃, the volume ratio of the gas agent (the volume of the introduced gas to the filling volume ratio of the catalyst) is 100-1000, and the treatment time is 4-12 hours; wherein the oxygen-containing gas is one of air, a mixture of oxygen and nitrogen or a mixture of oxygen and inert gas, and the volume fraction of the oxygen in the gas phase is 5-50%.

In the method, the volume ratio of the feeding amount of the aqueous solution containing ammonium nitrate in the step (3) to the catalyst is 0.1: 1-10: 1, preferably 1: 1-5: 1, wherein the mass percentage concentration of the aqueous solution of ammonium nitrate is 16-50%; the contact reaction conditions in the step (3) are as follows: the reaction pressure is 0.2-10 MPa, preferably 0.5-5 MPa, the reaction temperature is lower than the boiling point temperature of water under the pressure, preferably 20-100 ℃, and the reaction time is 1-24 hours, preferably 2-12 hours.

In the method, the temperature for introducing the nitrogen or the inert gas for treatment in the step (3) is 100-300 ℃, the volume ratio of the gas agent (the volume of the introduced gas to the filling volume ratio of the catalyst) is 100-1000, and the time is 4-12 hours.

In the method, the hydrogen-containing gas in the step (4) can be pure hydrogen or hydrogen containing inert gas, wherein the hydrogen volume percentage content in the hydrogen-containing gas is 5-100%, preferably 50-100%; the activating treatment conditions are as follows: the pressure is 0.2-10 MPa, the preferable pressure is 0.5-5 MPa, the temperature is 200-600 ℃, the preferable temperature is 250-500 ℃, and the time is 0.5-24 hours, the preferable time is 1-12 hours, and the more preferable time is 2-8 hours.

In the method, after the step (4), reaction materials are directly introduced into the reactor to carry out paraffin shape selective isomerization reaction.

The catalyst obtained by the method is applied to paraffin hydrocarbon shape-selective isomerization reaction, and the general process conditions are as follows: the volume airspeed is 0.5-4.0 h^-1The reaction temperature is 260-400 ℃, the reaction pressure is 2-20 MPa, and the hydrogen-hydrocarbon molar ratio is 2-10; wherein the paraffin selective isomerization reaction process is a process for converting long-chain paraffin into branched-chain paraffin.

The raw oil used by the catalyst obtained by the method in the paraffin hydrocarbon shape-selective isomerization reaction is wax-containing raw oil, and generally comprises diesel oil, AGO, VGO, white oil, hydrocracking tail oil, lubricating oil fraction and the like.

The method of the invention comprises the steps of preparing a catalyst precursor containing the ZSM-23 molecular sieve, contacting the catalyst precursor with a mixture of an organic amine compound aqueous solution and a halogen compound, and crystallizing at a certain temperature and pressure to form the molecular sieves (ZSM-22 and ZSM-23) aiming at special pore channels required by the isomerization reaction of long paraffin on the surface of the catalyst precursor. Due to the difference of the pore channel structures and the acidity of the two molecular sieves, the good synergistic effect is shown. The catalyst is used in the hydrotreating process of lubricating oil, and has the characteristics of high yield of lubricating oil base oil, high viscosity index and low pour point. But also can improve the utilization rate of the molecular sieve, avoid covering most of acid centers in the preparation process of the catalyst, greatly reduce the production cost of the catalyst while improving the activity and selectivity of the catalyst, avoid the generation of the wastewater which is difficult to treat in the traditional molecular sieve synthesizing process, and is beneficial to environmental protection.

Detailed Description

The techniques of the present invention are further illustrated by the following examples, but should not be construed as being limited thereto. The properties of the raw oil used are shown in Table 1.

Example 1

(1) 600 g of white carbon black, 40 g (dry basis 76%) of aluminum hydroxide (SB produced by Condean company, Germany), 100 g of ZSM-23 and 20 g of sesbania powder are fully mixed, then 420ml of 0.1M sodium hydroxide solution is added, the mixture is fully kneaded to form pasty plastic, cylindrical strips with the diameter of 1.5mm are formed on a strip extruding machine, the cylindrical strips are dried for 16 hours at the temperature of 100 ℃, and then the cylindrical strips are roasted for 4 hours at the temperature of 550 ℃ in an air atmosphere to obtain the catalyst carrier. With a gas containing H₂PtCl₆The catalyst carrier was impregnated with the solution in saturation, then dried at 100 ℃ for 8 hours, and calcined at 500 ℃ for 3 hours in an air atmosphere to obtain a catalyst containing 0.5wt% of Pt, and a catalyst precursor a was obtained. The ZSM-23 molecular sieve content in the catalyst is 13%. 100ml of the catalyst was diluted with 100ml of quartz sand and filled in a reactor of a pilot plant for evaluation of catalytic activity.

(2) Under the pressure of 2MPa and the temperature of 180 ℃, CH in the treatment fluid₃CHCl₂0.2 Mol/L of hexamethylene diamine and CH₃CHCl₂The molar ratio is 2, the space velocity of the feed volume (volume fed per hour to catalyst ratio) is 2.0h^-1And the treatment time is 36 hours. Then, the treatment solution is stopped, air is introduced at the speed of 800 gas agent volume ratio (the volume of the gas entering the catalyst and the filling volume ratio of the catalyst), the temperature is increased to 550 ℃, and the natural temperature reduction is started after the holding time is 6 hours.

(3) When the temperature is reduced to 60 ℃, the water solution containing ammonium nitrate is introduced into the catalyst bed layer under normal pressure, and the space velocity of the feeding volume is 2.0h^-1And stopping feeding water after keeping for 4 hours, introducing nitrogen at the speed of 500 parts by volume of the gas agent (the volume of the introduced gas to the filling volume of the catalyst), raising the temperature to 200 ℃, and stopping introducing nitrogen after keeping for 4 hours to obtain the catalyst B.

(4) Introducing pure hydrogen at the speed of 800 gas-agent volume ratio (the volume of the entering gas to the filling volume ratio of the catalyst) under the conditions of 1MPa of pressure and 420 ℃, increasing the temperature to 350 ℃, and keeping the temperature for 4 hours to activate the catalyst to obtain the catalyst C-1.

(5) Under the conditions of 5MPa of pressure and 380 ℃ of temperature, the hydrogen-hydrocarbon molar ratio is 4, and the volume space velocity is 6.0h^-1The catalyst was evaluated by feeding the starting materials shown in Table 1, and the products obtained after 4 hours of reaction were analyzed, and the evaluation results are shown in Table 2.

Example 2

The difference from example 1 is that ZSM-23 molecular sieve content in step (1) is 5%, and CH is contained in the treated liquid in step (2)₃CHCl₂The concentration is 0.6, the octanediamine is substituted by the hexanediamine, and the volume space velocity is 4.0h^-1The treatment time was 28 hours, the air treatment temperature was 580 ℃ and the treatment time was 4 hours. The evaluation results are shown in Table 2.

Example 3

The difference from example 1 is that the ZSM-23 molecular sieve content in step (1) is 20%, and CH is present in the treated liquid in step (2)₃I substituted CH₃CHCl₂Hexamethylenediamine and CH₃The molar ratio of I is 3. The evaluation results are shown in Table 2.

Example 4

The difference from the example 1 is that the ZSM-23 molecular sieve content in the step (1) is 30%, and the feed volume space velocity of the ammonium nitrate-containing aqueous solution in the step (3) is 1.0h^-1The water feeding time is 8 hours, the temperature is 25 ℃, the volume ratio of the nitrogen gas to the solvent is 300, the temperature is 260 ℃, and the time is 6 hours. The evaluation results are shown in Table 2.

Example 5

The same as example 1, except that the ZSM-23 molecular sieve content in step (1) was 45%, the pressure in step (4) was 0.5MPa, the reduction temperature was 320 ℃, the gas was a mixture of hydrogen and nitrogen (hydrogen contained in an amount of 60% by volume), the gas-to-solvent volume ratio was 600, and the reduction time was 2 hours. The evaluation results are shown in Table 2.

Comparative example 1

The difference from example 1 is that ZSM-23 molecular sieve is not contained in step (1).

Comparative example 2

100 g (76% dry basis) of aluminum hydroxide (SB produced by Condean, Germany), 24 g of ZSM-22 moleculesThe method comprises the steps of fully mixing a sieve, 10 g of ZSM-23 molecular sieve and 6 g of sesbania powder, adding 70ml of nitric acid solution with the concentration of 0.2M, fully kneading to form pasty plastic, extruding cylindrical strips with the diameter of 1.5mm on a strip extruding machine, drying the cylindrical strips at 100 ℃ for 16 hours, and roasting at 550 ℃ in an air atmosphere for 4 hours to obtain the catalyst carrier. With a gas containing H₂PtCl₆The catalyst carrier is saturated and impregnated by the solution, then dried for 8 hours at 100 ℃, and roasted for 3 hours at 500 ℃ in the air atmosphere to prepare the catalyst containing 0.5wt% of Pt. The evaluation conditions were the same as in example 1, and the evaluation results are shown in Table 2.

TABLE 1 Primary properties of the feed oils.

Table 2 evaluation results.

The evaluation results in Table 2 show that compared with the catalyst in the comparative example 2, the catalyst provided by the invention achieves the same reaction effect in the hydrotreating process of the lubricating oil fraction, and when the pour points of the lubricating oil base oils are similar, C is₅ ⁺The yield of liquid and the yield of the lubricating oil base oil are improved, C₅ ⁺The liquid yield is improved by about 2wt%, the base oil yield is improved by about 5wt%, and the viscosity index of the product is improved by more than 4 units, which shows that the catalyst has obvious effect in the process of treating the lubricating oil raw material.

Claims

1. A preparation method of a paraffin hydrocarbon shape-selective isomerization catalyst is characterized by comprising the following steps: (1) filling a catalyst precursor containing amorphous silica-alumina, ZSM-23 molecular sieve raw powder and an active metal component into a fixed bed reactor; (2) introducing an aqueous solution containing diamine compounds and halogenated hydrocarbons, carrying out contact reaction with a catalyst precursor, and then introducing oxygen-containing gas for treatment; (3) introducing an ammonium nitrate aqueous solution to contact and react with the catalyst precursor treated in the step (2), and then introducing nitrogen or inert gas to treat; (4) introducing gas containing hydrogen for activation treatment to obtain paraffin hydrocarbon shape-selective isomerization catalyst;

the diamine compound in the step (2) has C carbon atoms₅~C₈One or more of the diamines; the halogenated hydrocarbon is one or more of halogenated hydrocarbons containing 1-3 carbon atoms;

the ratio of the feeding amount of the diamine compound and halogenated hydrocarbon-containing aqueous solution in the step (2) to the volume of the catalyst is 0.1-10; the contact reaction conditions are as follows: the reaction pressure is 0.2-10 MPa, the reaction temperature is 150-220 ℃, and the reaction time is 12-100 hours.

2. The method of claim 1, wherein: the catalyst precursor of step (1) has the following properties: the amorphous silicon-aluminum SiO₂And Al₂O₃The molar ratio of (A) to (B) is 5-200; the content of the ZSM-23 molecular sieve raw powder is 1-50% by mass of the catalyst precursor; the active metal component is platinum or/and palladium, and the content of the active component is 0.1-10% by metal based on the total weight of the final catalyst.

3. The method of claim 1, wherein: the concentration of the halogenated hydrocarbon in the step (2) in the aqueous solution containing the diamine compound and the halogenated hydrocarbon is 0.01-2 mol/L.

4. The method of claim 1, wherein: the molar ratio of the diamine compound and the halogenated hydrocarbon in the step (2) is 0.5-5.

5. The method of claim 1, wherein: in the contact reaction condition of the step (2), the reaction pressure is 0.5-5 MPa.

6. The method of claim 1, wherein: and (3) introducing oxygen-containing gas for treatment in the step (2), wherein the temperature is 400-600 ℃, the volume ratio of the gas agent is 100-1000, and the treatment time is 4-12 hours.

7. The method of claim 1, wherein: the volume ratio of the feeding amount of the aqueous solution containing ammonium nitrate to the catalyst in the step (3) is 0.1: 1-10: 1, wherein the mass percentage concentration of the aqueous solution containing ammonium nitrate is 16-50%; the contact reaction conditions are as follows: the reaction pressure is 0.2-10 MPa, the reaction temperature is lower than the boiling point temperature of water under the pressure, and the reaction time is 1-24 hours.

8. The method of claim 1, wherein: and (3) introducing nitrogen or inert gas for treatment at the temperature of 100-300 ℃, wherein the volume ratio of the air agent is 100-1000, and the time is 4-12 hours.

9. The method of claim 1, wherein: the activation treatment conditions in the step (4) are as follows: the pressure is 0.2-10 MPa, the temperature is 200-600 ℃, and the time is 0.5-24 hours.

10. The method of claim 1, wherein: after the step (4), directly introducing a reaction material into the reactor to perform paraffin hydrocarbon shape selective isomerization reaction; wherein the raw oil used is wax-containing raw oil.

11. The method of claim 10, wherein: the process conditions for the paraffin hydrocarbon shape selective isomerization reaction are as follows: the volume airspeed is 0.5-4.0 h^-1The reaction temperature is 260-400 ℃, the reaction pressure is 2-20 MPa, and the hydrogen-hydrocarbon molar ratio is 2-10.