CN112679306B

CN112679306B - Selective hydrogenation method of carbon-dioxide post-hydrogenation process using crude hydrogen as hydrogen source

Info

Publication number: CN112679306B
Application number: CN201910988816.2A
Authority: CN
Inventors: 苟尕莲; 张峰; 谢元; 韩伟; 温翯; 车春霞; 谭都平; 梁玉龙; 李平智
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2019-10-17
Filing date: 2019-10-17
Publication date: 2022-07-05
Anticipated expiration: 2039-10-17
Also published as: CN112679306A

Abstract

A selective hydrogenation method of a carbon dioxide post-hydrogenation process by taking crude hydrogen as a hydrogen source comprises the following reaction process conditions in a single-stage fixed bed reactor: the inlet temperature of the reactor is 65-130 ℃, the pressure is 1.5-3.0 MPa, and the gas volume space velocity is 1500h^‑1～4000h^‑1In the catalytic reaction materials of the reactor, 70-93 v/v% of ethylene, 0.6-1.3 v/v% of acetylene and 0.01-0.5 v/v% of carbon trisection, and the ratio of hydrogen to alkyne in the materials at the inlet of the reactor is 2-3 (v/v). The hydrogenation method adopts a catalyst at least containing Pd, Ag, Ni and Cu, and adopts alumina with a bimodal pore distribution structure as a carrier, wherein the pore diameters are respectively 15-50 nm and 80-500 nm. The load of Ni, Cu and partial Pd adopts a microemulsion method, the particle size of the microemulsion is more than 50nm and less than 80nm, and most of Pd, Ni and Cu enter the macropores of the catalyst during the load. The loading of part of Pd adopts a supersaturation impregnation method, and most of Pd enters small holes on the surface of the carrier due to the capillary siphonage. The Ag is loaded by a saturated dipping method. The selective hydrogenation method has excellent anti-coking performance.

Description

Selective hydrogenation method of carbon-dioxide post-hydrogenation process using crude hydrogen as hydrogen source

Technical Field

The invention relates to a selective hydrogenation method of a carbon dioxide post-hydrogenation process by taking crude hydrogen as a hydrogen source.

Background

Ethylene obtained by petroleum hydrocarbon steam cracking contains acetylene with the mass fraction of 0.5-2.3%. When used in polymerization, acetylene in ethylene reduces the activity of the polymerization catalyst and affects the physical properties of the polymer, and must be removed. At present, acetylene in ethylene is removed by a selective hydrogenation method in industry, and the adopted catalyst mainly comprises noble metal catalysts such as Pd, Pt, Au and the like. In order to ensure that ethylene generated by acetylene hydrogenation and the original ethylene in the raw material are not hydrogenated continuously to generate ethane, which causes ethylene loss, higher hydrogenation selectivity of the catalyst must be ensured, and better economic benefit can be obtained.

The post-hydrogenation and pre-hydrogenation of the carbon dioxide are based on the position of the acetylene hydrogenation reactor relative to the demethanizer, wherein the hydrogenation reactor is positioned before the demethanizer for pre-hydrogenation and the hydrogenation reactor is positioned after the demethanizer for post-hydrogenation. The post-hydrogenation process has the advantages of multiple control means in the hydrogenation process, difficult temperature runaway and convenient operation, but the process is complex and needs to be independently prepared with hydrogen, and the post-hydrogenation process for carbon dioxide is easy to generate the hydrogenation dimerization reaction of acetylene due to the low content of hydrogen in the hydrogenation material to generate the four-carbon fraction which is further polymerized to generate an oligomer with wider molecular weight, commonly called as 'green oil'. The green oil is adsorbed on the surface of the catalyst and further forms coke to block the pore channels of the catalyst, so that reactants cannot diffuse to the surface of the active center of the catalyst, thereby causing the reduction of the activity of the catalyst.

For the post-carbon hydrogenation process of completely replacing hydrogen with crude hydrogen, a one-stage hydrogenation acetylene removal process is generally adopted, and a small amount of devices adopt a two-stage hydrogenation acetylene removal process. As the CO content in the crude hydrogen is high, the formylation reaction is more easily generated, oxygen-containing substances containing unsaturated bonds, such as aldehyde, ketone and the like, are formed, and are further polymerized to form larger green oil molecules, and the oxygen-containing compounds have longer retention time on the surface of the catalyst and have larger influence on the catalyst.

The noble metal catalyst has higher activity, but green oil is easily generated in the using process, so that the catalyst is coked and deactivated, and the stability and the service life of the catalyst are influenced. The patent CN200810119385.8 discloses a non-noble metal supported selective hydrogenation catalyst, a preparation method and application thereof, and the catalyst comprises a carrier, and a main active component and an auxiliary active component which are supported on the carrier, and is characterized in that the main active component is Ni, the auxiliary active component is at least one selected from Mo, La, Ag, Bi, Cu, Nd, Cs, Ce, Zn and Zr, the main active component and the auxiliary active component both exist in an amorphous state, the average grain size is less than 10nm, and the carrier is a non-oxidative porous material; and the catalyst is prepared by a micro-emulsification method.

US4404124 prepares a selective hydrogenation catalyst with a shell distribution of active components by a step-by-step impregnation method, and can be applied to selective hydrogenation of a carbon-dioxide fraction to eliminate acetylene in ethylene. US5587348 uses alumina as carrier, adds promoter silver to act with palladium, and adds fluorine chemically bonded with alkali metal to prepare the excellent carbon dioxide hydrogenation catalyst. The catalyst has the characteristics of reducing the generation of green oil, improving the selectivity of ethylene and reducing the generation amount of oxygen-containing compounds.

Patent CN1736589 reports a Pd/gamma-Al prepared by adopting a complete adsorption impregnation method₂O₃The hydrogenation catalyst is selected, and the green oil generation amount is large in the using process of the catalyst. Patent CN200810114744.0 discloses an unsaturated hydrocarbon selective hydrogenation catalyst and a preparation method thereof. The catalyst uses alumina as a carrier, uses palladium as an active component, and improves the impurity resistance and the coking resistance of the catalyst by adding rare earth, alkaline earth metal and fluorine, but the selectivity of the catalyst is not ideal.

The catalysts prepared by the method all adopt catalysts with single distribution of pore diameters, and are influenced by internal diffusion in the fixed bed reaction process, so that the selectivity of the catalysts is poor. The carrier with bimodal pore distribution can reduce the influence of internal diffusion and improve the selectivity of the catalyst while ensuring the high activity of the catalyst. ZL971187339 discloses a hydrogenation catalyst, the carrier is a honeycomb type carrier, which is a large-aperture carrier, and the selectivity of the catalyst is effectively improved. CN1129606 discloses a hydrocarbon conversion catalyst, the supported catalyst of which comprises alumina, nickel oxide, iron oxide, etc., and the catalyst comprises two pores, one of which is used for improving the catalytic reaction surface, and the other is favorable for diffusion. The patent CN101433842 provides a hydrogenation catalyst, which is characterized in that the catalyst has bimodal pore distribution, the radius of the small pore part can be 2-50 nm at most, and the radius of the large pore part can be 100-500 nm at most.

In the carbon hydrogenation reaction, the formation of green oil and the coking of the catalyst are important factors affecting the service life of the catalyst. The activity, selectivity and service life of the catalyst form the overall performance of the catalyst, and the methods listed above provide better ways for improving the activity and selectivity of the catalyst, but do not solve the problem that the catalyst is easy to coke, or solve the problem that the catalyst is easy to generate green oil and coke, but do not solve the problem of selectivity. Although the carrier with a macroporous structure can improve the selectivity, larger molecules generated by polymerization and chain growth reaction are easy to accumulate in the macropores of the carrier, so that the catalyst is coked and inactivated, and the service life of the catalyst is influenced.

ZL201310114077.7 discloses a hydrogenation catalyst, the active components in the catalyst are Pd, Ag and Ni, wherein the Pd and the Ag are loaded by adopting an aqueous solution impregnation method, and the Ni is loaded by adopting a W/O microemulsion impregnation method. After the method is adopted, Pd/Ag and Ni are positioned in pore channels with different pore diameters, green oil generated by reaction is saturated and hydrogenated in a large pore, and the coking amount of the catalyst is reduced.

However, the reduction temperature of Ni is usually about 500 ℃, and the reduced Pd atoms are easy to gather at the temperature, so that the activity of the catalyst is greatly reduced, the equivalent amount of active components needs to be greatly increased to compensate the activity loss, and the selectivity is reduced.

Disclosure of Invention

The invention aims to provide a carbon-reduced fraction post-hydrogenation method, in particular to a carbon-reduced fraction post-hydrogenation method which can adopt crude hydrogen as a hydrogen source and can reduce catalyst coking.

A selective hydrogenation method of a carbon dioxide post-hydrogenation process by taking crude hydrogen as a hydrogen source is characterized in that a hydrogenation material is a carbon dioxide fraction from the top of a deethanizer, and the hydrogenation material enters a fixed bed reactor to be subjected to gas phase hydrogenation to remove acetylene, and the hydrogen used in the hydrogenation reaction is crude hydrogen, wherein the content of CO is 0.1-1 v/v%, and the content of hydrogen is 30-50 v/v%. The reaction process conditions are as follows: the inlet temperature of the reactor is 55-130 ℃, the pressure is 1.5-3.0 MPa, and the gas volume space velocity is 1500-4000 h^-1. The catalyst carrier is alumina or mainly alumina, the alumina has a bimodal pore distribution structure, wherein the pore diameter of a small pore is 15-50 nm, the pore diameter of a large pore is 80-500 nm, the catalyst at least contains active components Pd, Ag, Ni and Cu, and the catalyst comprises, by mass of 100%, 0.07-0.1% of Pd, 0.03-0.5% of Ag, 0.5-5% of Ni, 0.5-5% of Cu and 1-5.5% of the total content of Ni and Cu; wherein the load of Pd adopts a saturated dipping method and a micro-emulsion method to dip twice; ni and Cu are loaded by a microemulsion method, and the particle size of the microemulsion is controlled to be more than 50nm and less than 500nm, so that the Ni and the Cu are mainly distributed in macropores of the carrier. The amount of Pd loaded by the microemulsion method is 1/100-1/200 of the total content of Ni and Cu, and the Pd loaded by the microemulsion method is after Ni and Cu are loaded by the microemulsion method.

A selective hydrogenation method for a carbon dioxide post-hydrogenation process by taking crude hydrogen as a hydrogen source is characterized in that materials from the top of a deethanizer in an ethylene device and metered crude hydrogen enter a fixed bed carbon dioxide hydrogenation reactor together for selective hydrogenation to remove alkyne in the fixed bed carbon dioxide hydrogenation reactor. The hydrogenation method is characterized in that a catalyst containing Pd, Ag, Ni and Cu components is filled in the fixed bed reactor, the catalyst has a bimodal pore size distribution, Ni, Cu and part of Pd in the catalyst are loaded by a microemulsion method, and the particle size of the microemulsion is larger than the pore size of a small pore and smaller than the maximum pore size of the large pore.

In the invention, firstly, active component palladium is loaded in the small holes, and then active components nickel/copper and part of palladium are loaded in the large holes. Acetylene and the like mainly undergo selective hydrogenation reaction in the small holes to generate ethylene. The by-products with larger molecular size generated in the reaction, mainly carbon four to carbon sixteen fractions, can easily enter the macropores and generate saturated hydrogenation reaction under the action of the nickel active components in the macropores. Since these molecules are saturated by hydrogenation, their molecular chains do not grow any longer and are therefore easily carried out of the reactor by the feed. The copper has the function of forming an alloy with the nickel, so that the reduction temperature of the nickel can be reduced, and the reduction temperature of the nickel can be further greatly reduced by a small amount of palladium entering the macropores, so that the palladium is not aggregated in the high-temperature reduction process. The initial activity selectivity of the catalyst is not affected by the reduction process.

The method is a single-stage fixed bed reactor, the hydrogen-alkyne ratio in the material at the inlet of the reactor is 2-3(v/v), and the inlet temperature of the reactor is 65-130 ℃. The reaction conditions are as follows: the reaction pressure is 1.5-3.0 Mpa, and the gas volume space velocity is 1500-4000 h^-1

In the crude hydrogen, the content of CO is 0.1-1 v/v%, and the content of hydrogen is 30-50 v/v%.

In the hydrogenation method, the hydrogenation raw material is a carbon-two fraction, wherein ethylene accounts for 70-93 v/v%, acetylene accounts for 0.6-1.3 v/v%, and a carbon-three fraction accounts for 0.01-0.5 v/v%.

The inventor finds that the content of the carbon three components in the material can reach 0.5 percent at most due to the remarkable enhancement of the coking resistance of the catalyst, and is far higher than the limit of the traditional hydrogenation method on the content of the carbon three fraction. Even if the separation unit has large fluctuation and the heavy component content in the material exceeds the standard, the hydrogenation unit can still normally operate.

In the catalyst, the selective hydrogenation reaction of acetylene occurs in a main active center consisting of Ag and Pd; ni and Cu are soaked in the macropores of the carrier in the form of microemulsion, and the green oil generated in the reaction is subjected to saturated hydrogenation on an active center consisting of Cu and Ni.

The Cu has the function of forming Ni/Cu alloy in the roasting process, effectively reduces the reduction temperature of the nickel in the reduction process, and reduces the polymerization of the Pd at high temperature.

For hydrogenation reaction, generally, before the catalyst is applied, the hydrogenation catalyst needs to be reduced first to ensure that the active component exists in a metal state, so that the catalyst can have hydrogenation activity. Because activation is a high temperature calcination process during catalyst preparation, the metal salt decomposes to metal oxides, which form clusters, which are typically nano-sized. Different oxides need to be reduced at different temperatures due to different chemical properties. However, for nano-sized metals, a critical temperature is around 200 ℃, and above this temperature, the aggregation of the metal particles is very significant. Therefore, the reduction temperature of the active component is very important for the hydrogenation catalyst.

The idea of the invention for solving the problem of catalyst coking is as follows: the selective hydrogenation reaction of acetylene takes place in the main active center composed of Ag and Pd, and the macromolecules such as green oil produced in the reaction can easily enter the macropores of the catalyst. In the macropores of the catalyst, a Ni/Cu component is loaded, and has a saturated hydrogenation function, and the green oil component can perform a saturated hydrogenation reaction in an active center of the Ni/Cu component. Because the double bonds are saturated by hydrogenation, the green oil component can not generate polymerization reaction any more or the polymerization reaction rate is greatly reduced, the chain growth reaction is terminated or delayed, a fused ring compound with huge molecular weight can not be formed, and the fused ring compound is easily carried out of the reactor by materials, so the coking degree on the surface of the catalyst is greatly reduced, and the service life of the catalyst is greatly prolonged.

In the present invention, the most part of Pd is impregnated by a supersaturated impregnation method. In the process of loading palladium by using the supersaturation impregnation method, the solution containing palladium enters pores faster due to the siphonage of the pores, the palladium exists in the form of chloropalladate ions, and the palladium is quickly targeted due to the chemical bond formed between the ions and hydroxyl on the surface of the carrier, so that the faster the solution enters the pore channels, the faster the loading speed is. It is more easily supported in the pores during the impregnation of Pd in the supersaturated impregnation method.

The method for controlling the Ni/Cu alloy to be positioned in the catalyst macropores is that Ni/Cu is loaded in the form of microemulsion, and the grain diameter of the microemulsion is larger than the pore diameter of carrier micropores and smaller than the maximum pore diameter of macropores. Ni and Cu metal salts are contained in the microemulsion and are difficult to enter the pore channels of the carrier with smaller size due to steric resistance, so that Ni and Cu are mainly concentrated in macropores.

In the invention, Cu and Ni are loaded together, so that the reduction temperature of Ni can be reduced, because the reduction temperature is required to reach 450-500 ℃ for completely reducing NiO, Pd can be caused to agglomerate at the temperature, and after the Cu/Ni alloy is formed, the reduction temperature can be reduced by more than 100 ℃ to 350 ℃ compared with the reduction temperature of pure Ni. Thereby relieving the agglomeration of Pd in the reduction process.

The invention is not particularly limited in the process of loading Ni, Cu and Pd in a microemulsion manner, and Ni, Cu and Pd can be distributed in macropores of the carrier as long as the particle size of the microemulsion with the particle size of more than 50nm and less than 500nm can be formed.

The loading process of the microemulsion method comprises the following steps: dissolving precursor salt in water, adding oil phase, surfactant and cosurfactant, and stirring to form microemulsion, wherein the oil phase is alkane or cycloalkane, the surfactant is ionic surfactant or nonionic surfactant, and the cosurfactant is organic alcohol.

The oil phase recommended by the invention is saturated alkane or cycloalkane, preferably C6-C8 saturated alkane or cycloalkane, preferably cyclohexane and n-hexane; the surfactant is an ionic surfactant or a nonionic surfactant, preferably a nonionic surfactant, and more preferably polyethylene glycol octyl phenyl ether or hexadecyl trimethyl ammonium bromide; the cosurfactant is an organic alcohol, preferably a C4-C6 alcohol, more preferably n-butanol or n-pentanol.

In the microemulsion, the weight ratio of the water phase to the oil phase is preferably 2-3, the weight ratio of the surfactant to the oil phase is preferably 0.15-0.6, and the weight ratio of the surfactant to the co-surfactant is preferably 1-1.2.

In the invention, a small amount of Pd is loaded on the surface of the Ni/Cu alloy, and the reduction temperature of Ni can be greatly reduced to below 200 ℃ and as low as 150 ℃.

Therefore, the better catalyst is Pd mainly existing in the small pores of the catalyst, Ni/Cu is located in the large pores of the catalyst, and the surface of Ni/Cu in the large pores has a small amount of Pd.

The Ni/Cu is impregnated in a micro-emulsion form in the preparation process of the catalyst. The Pd is impregnated by two methods, namely a supersaturated impregnation method and a micro-emulsion method, and the Ag is loaded by a saturated impregnation method.

The catalyst recommended by the invention is prepared by a more specific method, which comprises the following steps:

(1) dissolving precursor salts of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, fully stirring to form a microemulsion, and controlling the particle size of the microemulsion to be more than 50nm and less than 500 nm; adding a carrier into the prepared microemulsion, dipping for 0.5-4 hours, filtering out residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 300-600 ℃ to obtain a semi-finished catalyst A;

(2) dissolving a precursor salt of Pd in water, adjusting the pH value to 1.5-2.5, adding the semi-finished catalyst A into a Pd salt solution, soaking and adsorbing for 0.5-4 h, drying at 80-120 ℃ for 1-4 h, and roasting at 400-550 ℃ for 2-6 h to obtain a semi-finished catalyst B;

(3) loading Ag by adopting a saturated impregnation method, namely, preparing an Ag salt solution which is 80-110% of the saturated water absorption of the carrier, adjusting the pH value to be 1-5, and roasting the semi-finished catalyst B at 500-550 ℃ for 4-6 hours after loading Ag on the semi-finished catalyst B to obtain a semi-finished catalyst C;

(4) dissolving Pd precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, fully stirring to form a microemulsion, and controlling the particle size of the microemulsion to be more than 50nm and less than 500 nm; adding the semi-finished catalyst C into the prepared microemulsion, dipping for 0.5-4 hours, and filtering out residual liquid; drying at 80-120 ℃ for 1-6 hours, and roasting at 300-600 ℃ for 2-8 hours to obtain a semi-finished catalyst D.

(5) The semi-finished catalyst D was placed in a fixed bed reaction apparatus and the reaction was carried out using N2: and (3) reducing H2-1: 1 mixed gas at 150-200 ℃ for 4-8H to obtain the finished catalyst E.

The catalyst had the following characteristics: at the beginning of the hydrogenation reaction, the hydrogenation activity of palladium is high and is mainly distributed in the pores, so that the selective hydrogenation reaction of acetylene mainly occurs in the pores. With the prolonging of the operation time of the catalyst, a part of by-products with larger molecular weight are generated on the surface of the catalyst, and due to the larger molecular size, the substances enter the macropores more frequently and the retention time is longer, the hydrogenation reaction of double bonds can be generated under the action of the nickel catalyst, so that saturated hydrocarbon or aromatic hydrocarbon without isolated double bonds is generated, and substances with larger molecular weight are not generated any more. The catalyst has low reduction temperature in the preparation process, and the reduction temperature is 150-200 ℃.

After the catalyst is adopted, even if the reactant contains more heavy fractions, the green oil generation amount of the catalyst is greatly increased, and the activity and the selectivity of the catalyst still do not tend to be reduced. In view of the excellent properties of the catalyst, the catalyst can also be used for two-stage or three-stage hydrogenation in a carbon-two post-hydrogenation process using crude hydrogen as a hydrogen source.

The specific implementation mode is as follows:

the catalyst of the invention is characterized by the following methods in the preparation process: a dynamic light scattering particle size analyzer, wherein the particle size distribution of the microemulsion of the Ni/Cu alloy is analyzed on an M286572 dynamic light scattering analyzer; the pore volume, specific surface area and pore size distribution of the support were analyzed on a U.S. macken 9510 model mercury porosimeter; the contents of Pd, Ag, Ni and Cu in the catalyst were determined on an A240FS atomic absorption spectrometer.

Example 1

Carrier: a commercially available spherical alumina carrier with bimodal pore distribution and a diameter of 4mm was used. After roasting for 4 hours at 1000 ℃, the bimodal pore size distribution range is 15-35 nm and 80-200 mm, the water absorption rate is 63%, and the specific surface area is 50m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing 1.557g of nickel nitrate and 14.767g of copper nitrate, dissolving in 69mL of deionized water, adding 23g of cyclohexane, adding Triton X-1003.45 g of the mixture and 4.14g of n-butanol, fully stirring to form a microemulsion, soaking the weighed carrier into the prepared microemulsion, shaking for 60min, filtering out residual liquid, drying at 120 ℃ for 1 hour, and roasting at 300 ℃ for 8 hours to obtain the semi-finished catalyst A-1.

(2) Weighing 0.075g of palladium chloride, dissolving in 100mL of deionized water, adjusting the pH value to 1.8, soaking the semi-finished catalyst A-1 in the prepared Pd salt solution for 60min, drying at 120 ℃ for 1 hour, and roasting at 400 ℃ for 6 hours to obtain the semi-finished catalyst A-2.

(3) Weighing 0.472g of silver nitrate, dissolving the silver nitrate in 57mL of deionized water, adjusting the pH value to 3, soaking the semi-finished catalyst A-2 prepared in the step (2) in the prepared silver nitrate solution for preparing silver, shaking, drying at 120 ℃ for 1 hour after the solution is completely absorbed, and roasting at 500 ℃ for 6 hours to obtain the semi-finished catalyst A-3.

(4) Weighing 0.098g of palladium nitrate, dissolving in 70mL of deionized water, adding 23g of cyclohexane, adding 23g of Triton X-1003.45 g and adding 4.14g of n-butanol, fully stirring to form a microemulsion, dipping the semi-finished catalyst A-3 prepared in the step (3) into the prepared microemulsion, shaking for 60min, filtering out residual liquid, drying at 120 ℃ for 1 hour, and roasting at 300 ℃ for 8 hours to obtain the semi-finished catalyst A-4.

(5) Placing the semi-finished product catalyst A-4 obtained in the step (4) in a fixed bed reaction device, and using a molar ratio N₂:H₂The catalyst a was obtained by reducing the mixed gas at 190 ℃ for 5 hours in a ratio of 1: 1.

Dynamic light scattering measurement the microemulsion emulsion prepared in step (1) had a particle size of 53 nm.

The catalyst prepared by atomic absorption spectrometry was found to have a Pd content of 0.10%, a Ni content of 0.50%, a Cu content of 5.00%, and an Ag content of 0.30% in example 1.

Example 2

Carrier: a commercially available cylindrical alumina carrier with bimodal pore distribution, a diameter of 3mm and a length of 3mm was used. After roasting for 4 hours at 1030 ℃, the bimodal pore size distribution ranges from 18 to 38nm and 85 to 270mm, the water absorption rate is 61 percent, and the specific surface area is 43m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) 3.312g of nickel chloride and 7.411g of copper chloride are weighed, dissolved in 66mL of deionized water, added with 33g of cyclohexane, added with 9.90g of CATB and added with 11.39g of n-amyl alcohol, fully stirred to form microemulsion, the weighed carrier is dipped into the prepared microemulsion, shaken for 80min, filtered to remove residual liquid, dried for 4 hours at 100 ℃, and calcined for 6 hours at 400 ℃, so that the semi-finished catalyst B-1 is obtained.

(2) Weighing 0.112g of palladium nitrate, dissolving in 100mL of deionized water, adjusting the pH value to 1.8, then dipping the semi-finished catalyst B-1 into the prepared Pd salt solution, drying at 100 ℃ for 4 hours after dipping for 60min, and roasting at 450 ℃ for 4 hours to obtain the semi-finished catalyst B-2.

(3) Weighing 0.394g of silver nitrate, dissolving the silver nitrate into 57mL of deionized water, adjusting the pH value to 3, soaking the semi-finished catalyst B-2 prepared in the step (2) into the prepared silver nitrate solution containing silver, shaking, drying at 100 ℃ for 4 hours after the solution is completely absorbed, and roasting at 530 ℃ for 5 hours to obtain the semi-finished catalyst B-3.

(4) Weighing 0.086g of palladium chloride, dissolving in 70mL of deionized water, adding 33g of cyclohexane, adding 9.90g of CATB and 11.39g of n-amyl alcohol, fully stirring to form a microemulsion, dipping the semi-finished catalyst B-3 prepared in the step (3) into the prepared microemulsion, shaking for 80min, filtering out residual liquid, drying at 100 ℃ for 4 hours, and roasting at 400 ℃ for 6 hours to obtain the semi-finished catalyst B-4.

(5) Placing the semi-finished product catalyst B-4 obtained in the step (4) in a fixed bed reaction device, and using a molar ratio N₂:H₂Reducing the mixed gas at the temperature of 160 ℃ for 7h to obtain the finished catalyst B.

Dynamic light scattering measurement the particle size of the microemulsion emulsion prepared in step (1) was 55 nm.

The catalyst prepared by atomic absorption spectrometry was found to have a Pd content of 0.09%, a Ni content of 1.50%, a Cu content of 3.50%, and an Ag content of 0.25% in example 2.

Example 3

Carrier: a commercially available cloverleaf alumina carrier with double peak holes is adopted, the diameter is 2mm, and the length is 4 mm. After roasting at 1060 ℃ for 4 hours, the bimodal pore size distribution range is 20-42 nm and 90-360 mm, the water absorption rate is 58%, and the specific surface area is 37m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing 8.095g of nickel nitrate and 4.658g of copper chloride, dissolving in 62mL of deionized water, adding 30g of n-hexane, 12.00g of CATB and 13.20g of n-amyl alcohol, fully stirring to form microemulsion, soaking the weighed carrier into the prepared microemulsion, shaking for 70min, filtering out residual liquid, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 3 hours to obtain the semi-finished catalyst C-1.

(2) Weighing 0.109g of palladium nitrate, dissolving in 100mL of deionized water, adjusting the pH value to 1.8, soaking the semi-finished catalyst C-1 in the prepared Pd salt solution for 60min, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 3 hours to obtain the semi-finished catalyst C-2.

(3) Weighing 0.315g of silver nitrate, dissolving in 57mL of deionized water, adjusting the pH value to 3, soaking the semi-finished catalyst C-2 prepared in the step (2) in the prepared silver nitrate solution for preparing silver, shaking, drying at 110 ℃ for 3 hours after the solution is completely absorbed, and roasting at 510 ℃ for 6 hours to obtain the semi-finished catalyst C-3.

(4) Weighing 0.109g of palladium nitrate, dissolving in 70mL of deionized water, adding 30g of n-hexane, 12.00g of CATB and 13.20g of n-amyl alcohol, fully stirring to form a microemulsion, dipping the semi-finished catalyst C-3 prepared in the step (3) into the prepared microemulsion, shaking for 70min, filtering out residual liquid, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 3 hours to obtain the semi-finished catalyst C-4.

(5) Placing the semi-finished catalyst C-4 obtained in the step (4) in a fixed bed reaction device, and using a molar ratio N₂:H₂Reducing the mixed gas at the temperature of 170 ℃ for 6h to obtain the finished catalyst C.

Dynamic light scattering measurement the particle size of the microemulsion emulsion prepared in step (1) was 62 nm.

The catalyst prepared by atomic absorption spectrometry was found to have a Pd content of 0.08%, a Ni content of 2.60%, a Cu content of 2.20%, and an Ag content of 0.20% in example 3.

Example 4

Carrier: a commercially available clover-shaped alumina carrier with bimodal pore distribution is adopted, the diameter is 3mm, and the length is 3 mm. After roasting for 4 hours at 1090 ℃, the bimodal pore size distribution range is 22-45 nm and 100-420 mm, the water absorption rate is 56%, and the specific surface area is29m²(iv) g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) 8.611g of nickel chloride and 5.316g of copper nitrate are weighed and dissolved in 58mL of deionized water, 21g of n-hexane, 21g of Triton X-10010.50 g and 11.03g of n-butanol are added, the mixture is fully stirred to form microemulsion, the weighed carrier is soaked in the prepared microemulsion, the mixture is shaken for 90min, residual liquid is filtered out, the mixture is dried for 5 hours at the temperature of 90 ℃, and the mixture is roasted for 2 hours at the temperature of 600 ℃, so that the semi-finished catalyst D-1 is obtained.

(2) Weighing 0.100g of palladium chloride, dissolving in 100mL of deionized water, adjusting the pH value to 1.8, then soaking the semi-finished catalyst D-1 in the prepared Pd salt solution for 60min, drying at 90 ℃ for 5 hours, and roasting at 550 ℃ for 2 hours to obtain the semi-finished catalyst D-2.

(3) Weighing 0.142g of silver nitrate, dissolving in 57mL of deionized water, adjusting the pH value to 3, soaking the semi-finished catalyst D-2 prepared in the step (2) in the prepared silver nitrate solution for preparing silver, shaking, drying at 80 ℃ for 6 hours after the solution is completely absorbed, and roasting at 540 ℃ for 5 hours to obtain the semi-finished catalyst D-3.

(4) Weighing 0.100g of palladium chloride, dissolving in 70mL of deionized water, adding 21g of n-hexane, adding 21g of Triton X-10010.50 g and adding 11.03g of n-butanol, fully stirring to form a microemulsion, dipping the semi-finished catalyst D-3 prepared in the step (3) into the prepared microemulsion, shaking for 90min, filtering out residual liquid, drying at 90 ℃ for 5 hours, and roasting at 600 ℃ for 2 hours to obtain the semi-finished catalyst D-4.

(5) Putting the semi-finished catalyst D-4 obtained in the step (4) into a fixed bed reaction device, and using a molar ratio N₂:H₂Reducing the mixed gas at the temperature of 150 ℃ for 8h to obtain the finished catalyst D.

Dynamic light scattering measurement the particle size of the microemulsion emulsion prepared in step (1) was 65 nm.

The catalyst prepared by atomic absorption spectrometry was found to have a Pd content of 0.09%, a Ni content of 3.90%, a Cu content of 1.80%, and an Ag content of 0.09% in example 4.

Example 5

Carrier: miningA commercially available spherical alumina support with bimodal pore distribution and a diameter of 4mm was used. After roasting for 4 hours at 1130 ℃, the bimodal pore size distribution range is 25-50 nm and 110-500 mm, the water absorption is 50%, and the specific surface area is 20m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) 15.567g of nickel nitrate and 2.117g of copper chloride are weighed and dissolved in 50mL of deionized water, 25g of n-hexane, 15.00g of CATB and 15.00g of n-butanol are added, the mixture is fully stirred to form microemulsion, the weighed carrier is soaked in the prepared microemulsion, the mixture is shaken for 100min, residual liquid is filtered out, the mixture is dried for 6 hours at 80 ℃ and is roasted for 5 hours at 450 ℃, and the semi-finished catalyst E-1 is obtained.

(2) Weighing 0.087g of palladium nitrate, dissolving in 100mL of deionized water, adjusting the pH value to 1.8, soaking the semi-finished catalyst E-1 in the prepared Pd salt solution for 60min, drying at 80 ℃ for 6 hours, and roasting at 450 ℃ for 4 hours to obtain the semi-finished catalyst E-2.

(3) Weighing 0.047g of silver nitrate, dissolving in 57mL of deionized water, adjusting the pH value to 3, soaking the semi-finished catalyst E-2 prepared in the step (2) in the prepared silver nitrate solution for preparing silver, shaking, drying at 90 ℃ for 5 hours after the solution is completely absorbed, and roasting at 550 ℃ for 4 hours to obtain the semi-finished catalyst E-3.

(4) Weighing 0.087g of palladium nitrate, dissolving in 70mL of deionized water, adding 25g of n-hexane, 15.00g of CATB and 15.00g of n-butanol, fully stirring to form a microemulsion, dipping the semi-finished catalyst E-3 prepared in the step (3) into the prepared microemulsion, shaking for 100min, filtering out residual liquid, drying at 80 ℃ for 6 hours, and roasting at 450 ℃ for 5 hours to obtain the semi-finished catalyst E-4.

(5) Putting the semi-finished product catalyst E-4 obtained in the step (4) into a fixed bed reaction device, and using a molar ratio N₂:H₂Reducing the mixed gas at the temperature of 200 ℃ for 4h to obtain the finished catalyst E.

Dynamic light scattering measurement the particle size of the microemulsion emulsion prepared in step (1) was 60 nm.

The catalyst prepared by atomic absorption spectrometry was found to have a Pd content of 0.07%, a Ni content of 5.00%, a Cu content of 1.00%, and an Ag content of 0.03% in example 5.

Example 6

The same support as in example 5 was used, the catalyst preparation conditions were the same as in example 5, except that the loading of Pd was carried out by the saturated impregnation method. The contents of the various components are the same. Catalyst F was prepared.

Comparative example 1

The same support as in example 1 was used, and the catalyst preparation conditions were the same as in example 1 except that Cu was not supported. The contents of the other components except Cu were the same. Catalyst a0 was prepared.

Comparative example 2

The catalyst preparation procedure was the same as in example 2, except that Ni was not supported. The contents of the other components except Ni were the same. Catalyst B0 was prepared.

Comparative example 3

The same support as in example 3 was used, the catalyst preparation conditions were the same as in example 3, except that Cu was supported by the saturation impregnation method. The contents of the various components are the same. Catalyst C0 was prepared.

Comparative example 4

The catalyst preparation conditions were the same as in comparative example 4, except that Cu and Ni were supported by the saturation impregnation method in the first step. The contents of the various components are the same. Catalyst D0 was prepared.

Comparative example 5

Compared with the embodiment 1, the method is characterized in that a commercially available unimodal pore distribution carrier is adopted, the pore size distribution range is 15-35 nm, and the load of various metals is realized by a saturated impregnation method. The contents of the various components are the same. Catalyst a1 was prepared.

Comparative example 6

The difference compared to example 1 is that Cu in example 1 was replaced with Pb in the same content as Cu in example 1; the contents of other components and preparation conditions are unchanged. Catalyst a2 was prepared.

Comparative example 7

Compared with example 5, the difference is that the Cu in example 5 is replaced by Pb, and the content is the same as that of the Cu in example 1; the contents of other components and preparation conditions are unchanged. Catalyst F0 was prepared.

Effects of the implementation

Application of catalyst in hydrogenation reaction after carbon dioxide generation

Example 1, comparative example 6

Hydrogenation reaction conditions: the filling amount of the catalyst in the single-stage adiabatic fixed bed reactor is 50mL, the filling material is 50mL, and the space velocity of the reaction materials is as follows: 4000/h, operating pressure: 1.5MPa, a hydrogen-acetylene ratio of 2.0 and a reactor inlet temperature of 65 ℃. The reaction mass compositions are shown in tables 1 and 2 below.

Table 1 material composition:

reaction materials	C₂H₂	H₂	C₂H₄	C₃	CO
						Content (v/v%)	0.6	1.2	93	0.3	0.03

Table 2 run results:

in comparison with example 1, in comparative example 1, Cu was not supported, and although the initial acetylene conversion and selectivity were substantially the same as in example 1, after 1000 hours, they were significantly lower than in example 1. Indicating that the Cu loading or catalyst reduction temperature is important to improve the anti-coking performance. Or at a reduction temperature of 200 ℃, Ni with a saturated hydrogenation function cannot be completely reduced and does not exert a due effect.

Compared with the embodiment 1, the comparative example 5 is different from the embodiment 1 in that a commercially available unimodal pore distribution carrier is adopted, and the pore size distribution range is 15-35 nm. The initial activity is the same as that of the example 1, but the selectivity is far lower than that of the example 1, after running for 1000 hours, the activity selectivity is greatly reduced, and the coking amount is also far higher than that of the example 1. The reason that the selectivity is low and the coking amount is large is that the carrier does not contain macropores, and reaction products cannot be rapidly conveyed out of the micropores, so that excessive hydrogenation is caused, and larger green oil molecules are formed and are retained in the micropores.

Example 2, comparative example 2 comparison

Hydrogenation reaction conditions: the filling amount of the catalyst in the single-stage adiabatic fixed bed reactor is 50mL, the filling material is 50mL, and the space velocity of the reaction materials is as follows: 3000/h, operating pressure: 1.7MPa, a hydrogen acetylene ratio of 2.2 and a reactor inlet temperature of 80 ℃. The reaction mass compositions are shown in tables 3 and 4 below.

Table 3 material composition:

reaction mass	C₂H₂	H₂	C₂H₄	C₃	CO
						Content (v/v%)	0.8	1.76	88	0.2	0.044

TABLE 4 run results

Compared with the example 2, the Ni is not loaded in the comparative example 2, the initial acetylene conversion rate and the selectivity are the same as those in the example 2, but after 1000h, the acetylene conversion rate is obviously reduced compared with the example 2, and the coking amount is obviously higher than that in the example 2. The Ni is shown to have an important effect on improving the coking resistance of the catalyst.

Example 3, comparative example 3 comparison

Hydrogenation reaction conditions: the filling amount of the catalyst in the single-stage adiabatic fixed bed reactor is 50mL, the filling material is 50mL, and the space velocity of the reaction materials is as follows: 2500/h, operating pressure: 2.0MPa, a hydrogen-acetylene ratio of 2.5 and a reactor inlet temperature of 90 ℃. The reaction mass compositions are shown in tables 5 and 6 below.

Table 5 material composition:

reaction mass	C₂H₂	H₂	C₂H₄	C₃	CO
						Content (v/v%)	1	2.5	83	0.3	0.05

TABLE 6 run results

Compared with the embodiment 3, the Cu load in the comparative example 3 adopts a supersaturation impregnation method, the Cu is mainly distributed in small holes, the effect of effectively reducing the reduction temperature is not achieved, Ni in the catalyst cannot be completely reduced at the reduction temperature of 170 ℃, the saturated hydrogenation function cannot be completely exerted, the green oil generation amount of the catalyst is large, and a large amount of coke is formed. Coking covers the active components, resulting in reduced catalyst conversion.

Example 4, comparative example 4

Hydrogenation reaction conditions 1: the filling amount of the catalyst in the single-stage isothermal fixed bed reactor is 50mL, the filling amount is 50mL, and the space velocity of the reaction materials is as follows: 2000/h, operating pressure: 2.5MPa, a hydroacetylene ratio of 2.7 and a reactor inlet temperature of 130 ℃. The reaction mass compositions are shown in tables 7 and 8 below.

Table 7 material composition:

reaction mass	C₂H₂	H₂	C₂H₄	C₃	CO
						Content (v/v%)	1.2	3.24	75	0.5	0.11

TABLE 8 run results

Compared with the embodiment 4, the load of Cu and Ni adopts a supersaturation dipping method, most of Cu and Ni enter small holes and can not play the saturated hydrogenation function, the coking amount of the catalyst is large after 1000 hours, and the performance of the catalyst is reduced.

Example 5, comparative example 7 comparison

Hydrogenation reaction conditions: the filling amount of the catalyst in the single-stage isothermal bed reactor is 50mL, the filling material is 50mL, and the space velocity of the reaction materials is as follows: 1500/h, operating pressure: 3.0MPa, a hydrogen-acetylene ratio of 3.0 and a reactor inlet temperature of 110 ℃. The reaction mass compositions are shown in tables 9 and 10 below.

Table 9 material composition:

reaction mass	C₂H₂	H₂	C₂H₄	C₃	CO
						Content (v/v%)	1.3	3.9	70	0.15	0.1

TABLE 10 run results

In comparative example 5, the reason why the amount of coking is large in comparison with example 5 is that Pb fails to lower the reduction temperature of Ni, and Ni having a saturated hydrogenation function fails to function, and the amount of green oil produced is large, and a large amount of coking is likely to occur.

Claims

1. A selective hydrogenation method of a carbon dioxide post-hydrogenation process by taking crude hydrogen as a hydrogen source is characterized in that a hydrogenation material is a carbon dioxide fraction from the top of a deethanizer, and acetylene is removed by gas phase hydrogenation after the hydrogenation material enters a fixed bed reactor₂The content of the carbon dioxide is 30-50 v/v%, the content of CO is 0.1-1 v/v%, and the balance is methane, wherein the reaction process conditions are as follows: the inlet temperature of the reactor is 55-130 ℃, the pressure is 1.5-3.0 MPa, and the gas volume space velocity is 1500-4000/h; the catalyst carrier is alumina or mainly alumina, the alumina has a bimodal pore distribution structure, wherein the pore diameter of a small pore is 15-50 nm, the pore diameter of a large pore is 80-500 nm, the catalyst at least contains active components Pd, Ag, Ni and Cu, and the catalyst comprises, by mass of 100%, 0.07-0.1% of Pd, 0.03-0.5% of Ag, 0.5-5% of Ni, 0.5-5% of Cu and 1-5.5% of the total content of Ni and Cu;

wherein the load of Pd adopts a supersaturated impregnation method and a microemulsion method to carry out impregnation twice; ni and Cu are loaded by a microemulsion method, and the particle size of the microemulsion is controlled to be more than 50nm and less than 500nm, so that the Ni and the Cu are mainly distributed in macropores of the carrier; the amount of Pd loaded by the microemulsion method is 1/100-1/200 of the total content of Ni and Cu, and the Pd loaded by the microemulsion method is after Ni and Cu are loaded by the microemulsion method; the reduction temperature of the catalyst is 150-200 ℃.

2. The selective hydrogenation process for the carbo-hydrogenation process using crude hydrogen as the hydrogen source according to claim 1, characterized in that the reactor is a single-stage fixed bed reactor.

3. The selective hydrogenation process of a carbon-dioxide post-hydrogenation process using crude hydrogen as a hydrogen source according to claim 1, characterized in that: and (3) feeding the catalytic reaction materials into a single-stage fixed bed reactor, wherein the catalytic reaction materials comprise 70-93 v/v% of ethylene, 0.6-1.3 v/v% of acetylene and 0.01-0.5 v/v% of carbon three-fraction.

4. The selective hydrogenation method for the carbon dioxide post-hydrogenation process by using crude hydrogen as a hydrogen source according to claim 1, wherein the hydrogen-alkyne ratio in the inlet material of the single-stage fixed bed reactor is 2-3 v/v, and the inlet temperature of the reactor is 65-125 ℃.

5. The selective hydrogenation method for the carbon dioxide post-hydrogenation process by using crude hydrogen as the hydrogen source according to claim 1, wherein the catalyst, Ni, Cu and part of Pd are loaded in a microemulsion manner, and the process comprises the following steps: dissolving precursor salt in water, adding oil phase, surfactant and cosurfactant, and stirring to form microemulsion, wherein the oil phase is alkane or cycloalkane, the surfactant is ionic surfactant or nonionic surfactant, and the cosurfactant is organic alcohol.

6. The selective hydrogenation method of the carbon dioxide post-hydrogenation process using crude hydrogen as the hydrogen source according to claim 5, wherein the oil phase is C6-C8 saturated alkane or cycloalkane; the surfactant is an ionic surfactant or a nonionic surfactant; the cosurfactant is C4-C6 alcohol.

7. The selective hydrogenation method of the post-carbon hydrogenation process using crude hydrogen as the hydrogen source according to claim 6, wherein the oil phase is cyclohexane, n-hexane; the surfactant is a nonionic surfactant; the cosurfactant is n-butanol or n-pentanol.

8. The selective hydrogenation process of a carbon dioxide post-hydrogenation process using crude hydrogen as a hydrogen source as claimed in claim 7 wherein the surfactant is polyethylene glycol octyl phenyl ether or cetyl trimethyl ammonium bromide.

9. The selective hydrogenation method for the carbon dioxide post-hydrogenation process by using crude hydrogen as the hydrogen source according to claim 5, wherein in the microemulsion, the weight ratio of the water phase/the oil phase is 2-3, the weight ratio of the surfactant/the oil phase is 0.15-0.6, and the weight ratio of the surfactant/the co-surfactant is 1-1.2.

10. The selective hydrogenation method for the post-carbon hydrogenation process by using crude hydrogen as a hydrogen source according to claim 1, wherein 1/100-1/200 Pd in the total Ni + Cu content is loaded by a microemulsion method, and the particle size of the microemulsion is greater than 50nm and less than 500 nm.

11. The selective hydrogenation method of the carbon dioxide post-hydrogenation process using crude hydrogen as the hydrogen source according to claim 1, characterized in that the catalyst preparation step comprises:

(1) dissolving precursor salts of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form a microemulsion; adding a carrier into the prepared microemulsion, dipping for 0.5-4 hours, filtering out residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 300-600 ℃ to obtain a semi-finished catalyst A;

(3) carrying out Ag loading by a saturated impregnation method, namely, preparing an Ag salt solution which is 80-110% of the saturated water absorption of the carrier, adjusting the pH value to be 1-5, and roasting the semi-finished catalyst B at 500-550 ℃ for 4-6 hours after loading Ag on the semi-finished catalyst B to obtain a semi-finished catalyst C;

(4) dissolving Pd precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form a microemulsion; adding the semi-finished catalyst C into the prepared microemulsion, dipping for 0.5-4 hours, and filtering out residual liquid; drying at 80-120 ℃ for 1-6 hours, and roasting at 300-600 ℃ for 2-8 hours to obtain a semi-finished catalyst D;

(5) placing the semi-finished product catalyst D in a fixed bed reaction device, and using N₂：H₂A mixed gas of =1:1, at 150-200 deg.CAnd carrying out original treatment for 4-8 h to obtain a finished product catalyst E.