CN114308059B

CN114308059B - Alkyne-rich carbon four-fraction selective hydrogenation catalyst

Info

Publication number: CN114308059B
Application number: CN202011044839.7A
Authority: CN
Inventors: 展学成; 马好文; 王斌; 胡晓丽; 孙利民; 谢培思; 石文庆; 刘德华; 梁顺琴; 吕龙刚; 张宏伟; 潘曦竹
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2024-08-27
Anticipated expiration: 2040-09-28
Also published as: CN114308059A

Abstract

The invention relates to an alkyne-rich carbon four-fraction selective hydrogenation catalyst, wherein the carrier is alumina or mainly alumina, and has a bimodal pore distribution structure, wherein the pore diameter of small pores is 10-45 nm, and the pore diameter of large pores is 80-500 nm; the catalyst at least contains Pd, bi, ni, cu, wherein Ni and Cu are loaded in a micro-emulsion mode, bi is loaded in a solution mode, palladium is loaded in two modes of the solution mode and the micro-emulsion mode, the amount of Pd loaded in the micro-emulsion mode is 1/200-1/100 of the sum of the mass fractions of Ni and Cu, and the Ni, cu and Pd loaded in the micro-emulsion mode are distributed in macropores of 80-500 nm of the carrier. The specific surface area of the catalyst is 30-80 m ²/g. The catalyst of the invention is used for treating acetylene-rich carbon four-fraction and selectively hydrogenating and recovering butene, can obviously reduce the coking amount in the operation process of the catalyst, prolongs the service life of the catalyst, improves the operation period of the device and has good effect on improving the economic benefit of the process.

Description

Alkyne-rich carbon four-fraction selective hydrogenation catalyst

Technical Field

The invention relates to an alkyne-rich carbon four-fraction selective hydrogenation catalyst, in particular to an alkyne-rich carbon four-fraction selective hydrogenation recycle butene catalyst with high coking resistance.

Background

The cracking carbon four fraction of the byproduct of ethylene prepared by hydrocarbon high-temperature cracking generally contains 40-60% of butadiene by mass, and butadiene is an important monomer in the synthetic rubber industry. The butadiene is generally extracted from the cracked carbon four fraction by solvent extraction methods such as acetonitrile method, N-methylpyrrolidone method and dimethylformamide method. Because the alkyne concentration in the extracted carbon four fraction is higher, and the industrial utilization value is not available at present, only combustion treatment can be performed, but because the alkyne with high concentration has the danger of decomposition and explosion, the same amount of butadiene is discharged at the same time when the alkyne is separated in the industrial production due to the consideration of safety factors, and the alkyne can be combusted in a torch after being diluted by a proper amount of fractions such as butene, butane and the like. This not only causes great waste of resources, but also pollutes the environment. These factors all lead to the rise of energy consumption of the traditional carbon four-solvent extraction device, serious loss of carbon four-olefin resources and poor economy. Due to the influence of factors such as cracking depth and cracking technology, the alkyne content in the cracked carbon four fraction gradually increases, and more carbon four resources are required to be doped for dilution when the material is discharged, so that the loss of the carbon four resources is increased and the energy consumption is increased. Meanwhile, with the development of the organic synthesis industry technology, the limitation on the alkyne content in butadiene is more strict, and all the factors lead to the poor economical efficiency of the butadiene extraction device. The carbon tetraalkyne discharged by the part is treated by adopting a selective hydrogenation method, so that the vinyl acetylene and butadiene in the carbon tetraalkyne are converted into mono-olefins, the safety risk brought to the operation of a butadiene extraction device due to the discharge of the materials can be eliminated, and a large amount of mono-olefins can be recovered, thereby achieving the purposes of changing waste into valuables, saving energy and reducing consumption.

The selective hydrogenation catalyst is adopted, alkyne and butadiene in the C4 fraction are converted into butene through selective hydrogenation, and the selective hydrogenation catalyst is an effective utilization way of alkyne in the C4 fraction. The catalyst has high hydrogenation activity and selectivity, namely, the catalyst not only can effectively remove alkyne and butadiene, but also can reduce the loss of butene as much as possible, and the catalyst also has high stability so as to be suitable for long-period operation. The catalyst used for recovering butene through acetylene-rich carbon four-selective hydrogenation is usually a noble metal catalyst, and the hydrogenation performance of the catalyst is improved by adding different auxiliary agents.

ZL200810222182.1 discloses a selective hydrogenation catalyst and a preparation method thereof, wherein the catalyst takes alumina as a carrier and comprises active components of palladium, auxiliary agent of copper, auxiliary agent of X1 and auxiliary agent of X2, and the total mass of the catalyst is 100 percent: 0.1 to 0.5 percent of palladium, 0.1 to 6 percent of copper, 10.5 to 15 percent of X, 20.5 to 5 percent of X, and 0 to 2 percent of one or more auxiliary metals selected from cobalt, nickel, molybdenum, tungsten, lanthanum, silver, cerium, samarium and neodymium; wherein X1 is selected from element IVA and X2 is selected from alkali metal, alkaline earth metal or mixtures thereof. The catalyst is suitable for removing alkyne from the alkyne-rich residual material after butadiene extraction by selective hydrogenation, but the pores with the diameters of 5-15 nm in the pore structure of the catalyst account for more than 85% of the total pore volume, so that the catalyst is not beneficial to mass transfer of a dispersing agent and is also not beneficial to coke containing, and has certain limitation.

ZL201010182736.7 discloses a selective hydrogenation method of alkyne and diene in olefin flow, the catalyst used is palladium catalyst, and palladium loading adopts a spraying method. However, the catalyst preparation process requires irradiation of palladium catalyst precursor with ionizing radiation, and is not suitable for mass production applications.

The palladium catalyst is easy to generate unsaturated hydrocarbon polymerization reaction to generate green oil in the four-selective hydrogenation reaction process of the alkyne-rich carbon, and the deposition of the green oil macromolecules on the catalyst not only covers active centers to reduce the activity of the catalyst, but also can block pore channels to influence mass transfer. The service life of the catalyst is an important index for evaluating the comprehensive performance of the catalyst, and is related to the feasibility of industrial application, and the patent provides a better way for improving the activity and the selectivity of the catalyst, but does not solve the problem that the catalyst is easy to coke.

ZL201310114077.7 discloses a hydrogenation catalyst, the carrier is mainly alumina and has a bimodal pore distribution structure, the active components in the catalyst are Pd, ag and Ni, wherein Pd and Ag are loaded by adopting an aqueous solution impregnation method, and 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 the reaction is subjected to saturated hydrogenation in macropores, and the coking amount of the catalyst is reduced. However, the reduction temperature of Ni is about 450 ℃, pd atoms in a reduced state are easy to aggregate at the temperature, the activity of the catalyst is greatly reduced, the content of active components is required to be increased to compensate the activity loss, but the cost is increased, and the selectivity is reduced.

Disclosure of Invention

The invention aims to provide an alkyne-rich carbon four-fraction selective hydrogenation catalyst, in particular to an alkyne-rich carbon four-fraction selective hydrogenation butene recovery catalyst with excellent coking resistance, which is used for treating alkyne-rich carbon four-fraction containing butane, butene, butadiene, vinyl acetylene, butyne and other butadiene after extraction to recover butene, so that the added value of alkyne-rich carbon four-fraction resources can be improved, and the economic benefit of a device can be improved.

The catalyst is alumina or alumina mainly and has double peak pore distribution structure, with small pore size of 10-45 nm and large pore size of 80-500 nm. The catalyst at least contains Pd, bi, ni, cu, calculated by the mass of the catalyst being 100%, wherein the mass fraction of Pd is 0.15-0.5%, and the preferred mass fraction is 0.2-0.45%; the mass fraction of Ni is 0.50-5.0%, and the preferred mass fraction is 1.0-3.0%; the mass fraction of Bi is 0.05-0.50%, and the preferred mass fraction is 0.10-0.40%; the mass fraction of Cu is 0.5-3.0%, and the preferred mass fraction is 1.0-2.0%; the sum of the mass fractions of Ni and Cu is 1.0 to 8.0%, and the mass fraction is preferably 3.0 to 5.0%. Wherein Ni, cu and a small amount of Pd are loaded in a micro-emulsion mode, and the particle size of the micro-emulsion is controlled to be larger than the maximum pore diameter of a small pore of a bimodal pore carrier and smaller than the maximum pore diameter of a large pore, so that the micro-emulsion is distributed in the large pore of the carrier; the specific surface area of the catalyst is 30-80 m ²/g.

In the catalyst, the selective hydrogenation reaction of the carbon tetraalkyne and the butadiene occurs in a main active center composed of Pd and Bi, and the Bi is used as an auxiliary agent to mainly improve the hydrogenation selectivity of Pd. Ni, cu and a small amount of Pd are immersed in macropores of the carrier in the form of microemulsion, and macromolecules such as green oil generated in the reaction easily enter the macropores of the catalyst. The green oil is subjected to saturated hydrogenation on the active center composed of Cu, ni and Pd in the macropores, and the double bonds are subjected to hydrogenation saturation, so that the polymerization reaction of the green oil component can not occur any more or the polymerization reaction rate is greatly reduced, the chain growth reaction is stopped or delayed, a compound with larger molecular weight can not be formed, and the compound is easily carried out of the reactor by materials, therefore, the coking degree of the surface of the catalyst is greatly reduced, and the regeneration period and the operation life of the catalyst are greatly prolonged.

Most of palladium is supported by a solution method, and a supersaturation impregnation method is preferable. The solution containing palladium enters the pores more rapidly due to the siphoning effect of the pores, the palladium exists in the form of palladium chloride acid ions, and the palladium is targeted rapidly due to the fact that the ions can form chemical bonds with hydroxyl groups on the surface of the carrier, so that the faster the solution enters the pore channels, the faster the loading speed is. So that it is more easily supported in the pores during impregnation of Pd by the supersaturation impregnation method.

The loading of Bi is carried out by a solution method, preferably a saturated impregnation method, and the loading sequence is carried out after the supersaturation impregnation of Pd. The step of loading Pd by the microemulsion method is carried out after the step of loading Ni and Cu by the microemulsion method; other load sequencing is not limited.

For hydrogenation reaction, the hydrogenation catalyst is generally reduced before the catalyst is applied, so that the active components exist in a metal state, and the catalyst has hydrogenation activity. Because high temperature calcination is an activation process during catalyst preparation, the metal salt breaks down into metal oxides, which form clusters, which are typically nano-sized. For hydrogenation reaction, the hydrogenation catalyst is generally reduced before the catalyst is applied, so that the active components exist in a metal state, and the catalyst has hydrogenation activity. The different oxide reduction temperatures are different, but for nano-sized active metal components around 200 ℃ is an important critical temperature beyond which significant agglomeration of metal particles occurs. Therefore, reducing the reduction temperature of the active component is of great importance for hydrogenation catalysts.

Complete reduction of NiO alone generally requires a reduction temperature of 450-500 ℃ at which agglomeration of Pd is caused. The loading of Cu with Ni can reduce the reduction temperature of Ni because after Cu/Ni alloy is formed, the reduction temperature can be reduced to about 350 ℃ compared with that of purer Ni, thereby alleviating Pd agglomeration during reduction.

The inventors have unexpectedly found that the reduction temperature of Ni can be greatly reduced by loading a small amount of Pd on the surface of Ni/Cu alloy, and can be lower than 200 ℃.

The method for controlling Ni, cu and Pd to be positioned in the catalyst macropores in the invention is that Ni, cu and Pd are loaded in the form of microemulsion, and the particle size of the microemulsion is larger than the maximum pore diameter of the micropores of the bimodal pore carrier and smaller than the maximum pore diameter of macropores. The Ni, cu, pd metal salts are contained in the microemulsion and are difficult to enter into the pore channels of the carrier with smaller size due to space resistance, thus being distributed in the macropores of the carrier. The Pd amount loaded by the microemulsion method is 1/200-1/100 of the sum of the mass fractions of Ni and Cu.

The carrier adopted by the invention is required to have a bimodal pore distribution structure, in particular to have macropores with the pore diameter of 80-500 nm, and the pore diameter of the micropores is 10-45 nm. The carrier is alumina or mainly alumina, and the Al ₂O₃ crystal form is preferably alpha and theta mixed crystal form. The alumina content in the catalyst carrier is preferably 80% or more, and other metal oxides such as magnesia, titania and the like may be contained in the carrier.

The present invention is not particularly limited to the process of loading Ni, cu and Pd in the form of microemulsion, and Ni, cu and Pd can be distributed in the macropores of the carrier as long as the particle size of the microemulsion is formed between the maximum pore diameters of the micropores and the maximum pore diameters of the macropores of the carrier.

The invention also recommends a method, and the microemulsion mode loading process comprises the following steps: dissolving precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion, wherein the oil phase is alkane or cycloalkane, the surfactant is an ionic surfactant and/or a nonionic surfactant, and the cosurfactant is organic alcohol.

The kinds and addition amounts of the oil phase, the surfactant and the cosurfactant are not particularly limited in the present invention, and may be determined according to the pore structure of the precursor salt and the carrier.

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 and/or a nonionic surfactant, preferably a nonionic surfactant, more preferably polyethylene glycol octyl phenyl ether (Triton X-100) or sorbitan monooleate polyoxyethylene ether (tween 80); the cosurfactant is an organic alcohol, preferably a C4-C6 alcohol, more preferably n-butanol and/or n-pentanol.

In the microemulsion of the invention, the recommended mass ratio of the water phase to the oil phase is 2-3, the mass ratio of the surfactant to the oil phase is 0.15-0.6, and the mass ratio of the surfactant to the cosurfactant is 1-1.2.

The catalyst of the invention is preferably prepared by a process comprising the steps of:

(1) Dissolving precursor salt of Ni and Cu in water, adding oil phase, surfactant and cosurfactant, stirring thoroughly to form microemulsion, controlling the particle size of the microemulsion to be larger than the largest pore diameter of the small pores and smaller than the largest pore diameter of the large pores. And adding the carrier into the prepared microemulsion, soaking for 0.5-4 hours, and filtering out residual liquid. Drying at 60-150 deg.c for 1-6 hr and roasting at 300-600 deg.c for 2-8 hr. To obtain a semi-finished catalyst A.

(2) Dissolving Pd precursor salt in water, regulating pH to 1.5-2.5, adding the semi-finished catalyst A into Pd salt solution, soaking and adsorbing for 0.5-4 hr, drying at 60-150 deg.c for 1-6 hr, and roasting at 400-550 deg.c for 2-6 hr to obtain semi-finished catalyst B.

(3) The loading of Bi is carried out by a solution saturation impregnation method of Bi salt, the semi-finished catalyst B is precipitated for 0.5 to 2 hours after loading Bi, and then is dried for 1 to 6 hours at 60 to 150 ℃, and is baked for 4 to 6 hours at 500 to 550 ℃. Semi-finished catalyst C is obtained.

(4) Dissolving Pd precursor salt in water, adding metered oil phase, surfactant and cosurfactant, and fully stirring to form microemulsion, wherein the particle size of the microemulsion is controlled to be larger than the maximum pore diameter of the small pores and smaller than the maximum pore diameter of the large pores. And adding the semi-finished product C into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying at 60-150 ℃ for 1-6 hours, and roasting at 300-600 ℃ for 2-8 hours to obtain the required catalyst.

In the above preparation steps, the step (1) and the step (2) may be interchanged, the step (3) follows the step (2), and the step (4) follows the step (1).

The carrier in the step (1) can be spherical, cylindrical, clover-shaped, tooth-shaped, clover-shaped and the like.

The precursor salts of Ni, cu, bi and Pd in the above steps are soluble salts, and can be nitrate salts, chloride salts or other soluble salts thereof.

The catalyst has the following characteristics: at the beginning of the hydrogenation reaction, the selective hydrogenation reaction of the carbon tetraalkyne and butadiene occurs mainly on the main active center consisting of Pd and Bi in the pores. With the extension of the catalyst running time, a part of byproducts with larger molecular weight are generated on the surface of the catalyst, and the substances enter the macropores more due to larger molecular size, and the stay time is longer, so that double bond hydrogenation reaction can occur under the action of the nickel catalyst, saturated hydrocarbon or aromatic hydrocarbon without isolated double bonds is generated, and substances with larger molecular weight are not generated. The catalyst of the present invention can reduce the reduction treatment temperature of the catalyst to below 200 deg.c.

The catalyst of the invention is reduced at a reduction temperature of 150-200 ℃ before being put into hydrogenation reaction.

After the catalyst of the invention is adopted, even if the reactant contains more carbon tetrayne and butadiene, the catalyst activity and selectivity still keep higher level, and the coking amount of the catalyst is low.

Drawings

FIG. 1 is a TPR spectrum of Cu/Ni alloy and Pd-Cu/Ni alloy.

Detailed Description

The analysis method comprises the following steps:

The following analytical characterization methods are used in the preparation process of the catalyst: analyzing the particle size distribution of the microemulsion on a dynamic light scattering particle size analyzer; the specific surface area and pore size of the carrier were analyzed using GB/T21650; the mass fraction of the catalyst composition is determined by adopting the general rule of atomic absorption spectrometry (GB/T15337) and the general rule of chemical reagent flame atomic absorption spectrometry (GB/T19723); the composition of cleaved carbon four was assayed using SH/T1141 analysis.

The invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto.

Example 1

Catalyst carrier:

A commercially available bimodal pore distribution spherical alumina carrier was used, 4mm in diameter. After roasting for 4 hours at 1020 ℃, the bimodal pore size distribution range is 12-35 nm and 80-400 nm, and the specific surface area is 45m ²/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) Nickel nitrate and copper chloride are weighed and dissolved in 60mL of deionized water, 20g of cyclohexane is added, triton X-100 g of normal butanol is added, 7g of normal butanol is added, the mixture is fully stirred to form microemulsion, 100g of the weighed and high-temperature roasted carrier is immersed into the prepared microemulsion, the mixture is shaken for 30min, residual liquid is filtered, and the mixture is washed by deionized water. Drying at 80deg.C for 6 hr, and calcining at 400deg.C for 6 hr. Referred to as semi-finished catalyst C1-A.

(2) Preparing palladium chloride into an active component impregnating solution, adjusting the pH to 2.0, impregnating the semi-finished catalyst C1-A into the prepared Pd salt solution for 30min, drying at 80 ℃ for 6 hours, and roasting at 500 ℃ for 4 hours. Semi-finished catalyst C1-B is obtained.

(3) Weighing bismuth nitrate to prepare an acidic solution, immersing the semi-finished catalyst C1-B prepared in the step (2) in the prepared bismuth nitrate solution, shaking, drying at 130 ℃ for 3 hours after the solution is completely absorbed, and roasting at 500 ℃ for 6 hours to obtain the semi-finished catalyst C1-C.

(4) Palladium chloride is weighed and dissolved in 60mL of deionized water, 20g of cyclohexane is added, triton X-100 g is added, 7g of n-butanol is added, the mixture is fully stirred to form microemulsion, 100g of semi-finished catalyst C1-C is weighed and placed in the prepared microemulsion, the mixture is shaken for 30min, residual liquid is filtered, and the mixture is washed by deionized water. Drying at 80deg.C for 6 hr, and calcining at 400deg.C for 6 hr. The desired catalyst C1 was obtained.

The particle size of the microemulsion prepared in the steps (1) and (4) is 61nm as measured by a dynamic light scattering method.

Reduction of the catalyst:

Before use, the mixture is placed in a fixed bed reaction device, and is subjected to reduction treatment for 8 hours at the temperature of 200 ℃ by using mixed gas with the molar ratio of N ₂:H₂ =1:1.

Example 2

And (3) a carrier:

a commercially available bimodal pore distribution spherical alumina carrier was used, 3mm in diameter. After roasting for 4 hours at 1010 ℃, the bimodal pore size distribution ranges from 10 nm to 40nm and from 90 nm to 450nm, and the specific surface area is 49m ²/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) Nickel nitrate and copper chloride are weighed and dissolved in 70mL of deionized water, 26g of normal hexane is added, 80 g of tween is added, 9g of normal octanol is added, the mixture is fully stirred to form microemulsion, 100g of the weighed and high-temperature roasted carrier is immersed into the prepared microemulsion, the microemulsion is shaken for 90min, residual liquid is filtered out, the mixture is dried at 100 ℃ for 5 hours, and the mixture is roasted at 500 ℃ for 4 hours. Referred to as semi-finished catalyst C2-A.

(2) And (3) weighing palladium chloride, dissolving in 70mL of deionized water, adding 26g of normal hexane, adding 8010g of tween, adding 9g of n-octanol, stirring fully to form microemulsion, immersing the semi-finished catalyst C2-A prepared in the step (1) into the prepared microemulsion, shaking for 90min, filtering out residual liquid, drying at 100 ℃ for 5 hours, and roasting at 500 ℃ for 4 hours. Obtaining a semi-finished product C2-B.

(3) Preparing palladium chloride into an active component impregnating solution, adjusting the pH to 1.8, impregnating the semi-finished catalyst C2-B prepared in the step (2) into the prepared Pd salt solution, drying at 100 ℃ for 5 hours after 60 minutes, and roasting at 400 ℃ for 6 hours. Semi-finished catalyst C2-C is obtained.

(4) Weighing bismuth nitrate to prepare an acidic solution, immersing the semi-finished catalyst C2-C prepared in the step (3) in the prepared bismuth nitrate solution, shaking, drying at 140 ℃ for 2 hours after the solution is completely absorbed, and roasting at 500 ℃ for 4 hours to obtain the catalyst C2.

The particle size of the microemulsion prepared in the steps (1) and (2) is 54nm as measured by a dynamic light scattering method.

Reduction of the catalyst:

Before use, the mixture is placed in a fixed bed reaction device, mixed gas with the molar ratio of N ₂:H₂ =1:1 is used,

Reduction treatment was carried out at 150℃for 8h.

Example 3

And (3) a carrier:

A commercially available bimodal pore distribution spherical alumina carrier was used, 4mm in diameter. After roasting for 4 hours at 1030 ℃, the bimodal pore size distribution ranges from 15 nm to 45nm and from 100nm to 500nm, and the specific surface area is 43m ²/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) The palladium nitrate is weighed and dissolved in deionized water, the pH value is adjusted to be 2, and 100g of the weighed and high-temperature roasted carrier is soaked in the prepared Pd salt solution for 90min, and then is dried for 4 hours at 120 ℃ and roasted for 4 hours at 500 ℃. To obtain the semi-finished catalyst C3-A.

(2) Nickel nitrate and copper chloride are weighed and dissolved in 96mL of deionized water, 33g of cyclohexane, 8g of Triton X-100 g of normal butanol and 8g of normal butanol are added, the mixture is fully stirred to form microemulsion, the semi-finished catalyst C3-A prepared in the step (1) is immersed into the prepared microemulsion, the microemulsion is shaken for 240min, residual liquid is filtered, and the mixture is dried for 3 hours at 120 ℃ and baked for 2 hours at 600 ℃. Referred to as semi-finished catalyst C3-B.

(3) Weighing bismuth nitrate to prepare an acidic solution, immersing the semi-finished catalyst C3-B prepared in the step (2) in the prepared bismuth nitrate solution, shaking, drying at 150 ℃ for 2 hours after the solution is completely absorbed, and roasting at 500 ℃ for 6 hours to obtain the semi-finished catalyst C3-C.

(4) And (3) weighing palladium nitrate, dissolving in 96mL of deionized water, adding 33g of cyclohexane, adding TritonX-100 g of butanol, adding 8g of n-butanol, stirring fully to form microemulsion, dipping the semi-finished catalyst C3-C prepared in the step (3) into the prepared microemulsion, shaking for 240min, filtering out residual liquid, drying at 120 ℃ for 3 hours, and roasting at 600 ℃ for 2 hours. The desired catalyst C3 was obtained.

And (3) measuring the particle size of the microemulsion prepared in the steps (2) and (4) by a dynamic light scattering method to be 200nm.

Reduction of the catalyst:

Before use, the mixture is placed in a fixed bed reaction device, and is subjected to reduction treatment for 8 hours at the temperature of 150 ℃ by pure hydrogen.

Example 4

And (3) a carrier:

Adopts a commercial bimodal pore distribution spherical alumina-titania carrier, the mass fraction of the titania is 20 percent, and the diameter is 3mm. After roasting for 4 hours at 1020 ℃, the bimodal pore size distribution ranges from 12 nm to 43nm and from 90 nm to 460nm, and the specific surface area is 48m ²/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) Nickel chloride and copper nitrate are weighed and dissolved in 80mL of deionized water, 40g of n-heptane is added, 80 g of tween is added, 17g of n-amyl alcohol is added, the mixture is fully stirred to form microemulsion, 100g of the weighed and high-temperature roasted carrier is immersed into the prepared microemulsion, the microemulsion is shaken for 180min, residual liquid is filtered out, the mixture is dried at 80 ℃ for 4 hours, and the mixture is roasted at 600 ℃ for 2 hours. Referred to as semi-finished catalyst C4-A.

(2) And (3) weighing palladium chloride, dissolving in 80mL of deionized water, adding 40g of n-heptane, adding 8020g of tween, adding 17g of n-amyl alcohol, stirring fully to form microemulsion, immersing the semi-finished catalyst C4-A prepared in the step (1) into the prepared microemulsion, shaking for 180min, filtering out residual liquid, drying at 80 ℃ for 4 hours, and roasting at 600 ℃ for 2 hours. Referred to as semi-finished catalyst C4-B.

(3) And (3) weighing palladium chloride, dissolving in deionized water, adjusting the pH to 2.2, soaking the semi-finished catalyst C4-B prepared in the step (2) in the prepared Pd salt solution for 120min, drying at 130 ℃ for 3 hours, and roasting at 550 ℃ for 2 hours. To obtain a semi-finished catalyst C4-C.

(4) Weighing bismuth nitrate to prepare an acidic solution, immersing the semi-finished catalyst C4-C prepared in the step (3) in the prepared bismuth nitrate solution, shaking, drying at 100 ℃ for 4 hours after the solution is completely absorbed, and roasting at 500 ℃ for 2 hours to obtain the required catalyst C4.

And (3) measuring the particle size of the microemulsion prepared in the steps (1) and (2) by a dynamic light scattering method to be 48nm.

Reduction of the catalyst:

Example 5

And (3) a carrier:

Adopts a commercial bimodal pore distribution spherical alumina-magnesia carrier, wherein the mass fraction of magnesia is 3 percent, and the diameter is 3mm. After roasting for 4 hours at 1050 ℃, the bimodal pore size distribution ranges from 15 nm to 40nm and from 100 nm to 450nm, and the specific surface area is 38m ²/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) And (3) weighing palladium chloride, dissolving in deionized water, regulating the pH value to be 2.5, soaking the carrier in the prepared Pd salt solution for 120min, drying at 130 ℃ for 3 hours, and roasting at 500 ℃ for 2 hours to obtain the semi-finished catalyst C5-A.

(2) Weighing bismuth nitrate to prepare an acidic solution, immersing the semi-finished catalyst C5-A prepared in the step (1) in the prepared bismuth nitrate solution, shaking, drying at 100 ℃ for 4 hours after the solution is completely absorbed, and roasting at 500 ℃ for 8 hours to obtain the semi-finished catalyst C5-B.

(3) Weighing nickel chloride and copper nitrate, dissolving in 90mL of deionized water, adding 42g of normal hexane, adding 18g of cetyltrimethylammonium bromide (CTAB), adding 16g of normal hexanol, stirring fully to form a microemulsion, dipping the semi-finished catalyst C5-B prepared in the step (2) into the prepared microemulsion, shaking for 180min, filtering out residual liquid, drying at 70 ℃ for 6 hours, and roasting at 600 ℃ for 2 hours to obtain the semi-finished catalyst C5-C.

(4) Weighing palladium chloride, dissolving in 90mL deionized water, adding 42g of normal hexane, adding 18g of CTAB, adding 16g of normal hexanol, stirring fully to form microemulsion, immersing the prepared semi-finished catalyst C5-C into the prepared microemulsion, shaking for 180min, filtering out residual liquid, drying at 70 ℃ for 6 hours, and roasting at 600 ℃ for 2 hours. The desired catalyst C5 was obtained.

And (3) measuring the particle size of the microemulsion prepared in the steps (3) and (4) by a dynamic light scattering method to be 65nm.

Reduction of the catalyst:

Before use, the mixture is placed in a fixed bed reaction device, and is subjected to reduction treatment for 8 hours at the temperature of 180 ℃ by using mixed gas with the molar ratio of N ₂:H₂ =1:1.

Example 6

And (3) a carrier:

Adopts a commercial bimodal pore distribution spherical alumina-magnesia carrier, wherein the mass fraction of magnesia is 3 percent, and the diameter is 3mm. After being roasted for 4 hours at 990 ℃, the bimodal pore diameter distribution ranges from 15 nm to 40nm and from 100nm to 450nm, and the specific surface area is 62m ²/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) Nickel chloride and copper nitrate are weighed and dissolved in 90mL of deionized water, 42g of n-pentane is added, 18g of cetyltrimethylammonium bromide (CTAB) is added, 16g of n-hexanol is added, the mixture is fully stirred to form microemulsion, 100g of the weighed carrier baked at high temperature is immersed in the prepared microemulsion, the microemulsion is shaken for 100min, residual liquid is filtered, and the solution is dried at 70 ℃ for 6 hours and baked at 600 ℃ for 2 hours. Referred to as semi-finished catalyst C6-A.

(2) And (3) weighing palladium chloride, dissolving in deionized water, adjusting the pH to 1.8, soaking the semi-finished catalyst C6-A in the prepared Pd salt solution for 120min, drying at 130 ℃ for 3 hours, and roasting at 550 ℃ for 2 hours. To obtain the semi-finished catalyst C6-B.

(3) Weighing bismuth nitrate to prepare an acidic solution, immersing the semi-finished catalyst C6-B prepared in the step (2) in the prepared bismuth nitrate solution, shaking, drying at 100 ℃ for 4 hours after the solution is completely absorbed, and roasting at 500 ℃ for 2 hours to obtain the semi-finished catalyst C6-C.

(4) And (3) weighing palladium chloride, dissolving in 90mL of deionized water, adding 42g of n-pentane, adding 18g of CTAB (CTAB), adding 16g of n-hexanol, stirring fully to form a microemulsion, immersing the semi-finished catalyst C6-C prepared in the step (3) into the prepared microemulsion, shaking for 100min, filtering out residual liquid, drying at 70 ℃ for 6 h, and roasting at 600 ℃ for 2h. The desired catalyst C6 was obtained.

The particle size of the microemulsion prepared in the steps (1) and (4) is 65nm as measured by a dynamic light scattering method.

Reduction of the catalyst:

Example 7

And (3) a carrier:

A commercially available bimodal pore distribution spherical alumina carrier was used, 3mm in diameter. After roasting for 4 hours at 1000 ℃, the bimodal pore size distribution range is 15-45 nm and 100-400 nm, and the specific surface area is 50m ²/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) Nickel chloride and copper nitrate are weighed and dissolved in 70mL of deionized water, 30g of normal hexane is added, 80 g of tween is added, 16g of normal amyl alcohol is added, the mixture is fully stirred to form microemulsion, 100g of the weighed and high-temperature roasted carrier is immersed into the prepared microemulsion, the microemulsion is shaken for 90min, residual liquid is filtered out, the mixture is dried at 80 ℃ for 5 hours, and the mixture is roasted at 500 ℃ for 4 hours, so that the semi-finished catalyst C7-A is obtained.

(2) And (3) weighing palladium chloride, dissolving in deionized water, regulating the pH value to be 1.6, soaking the semi-finished catalyst C7-A in the prepared Pd salt solution for 60min, drying at 100 ℃ for 5 hours, and roasting at 400 ℃ for 6 hours to obtain the semi-finished catalyst C7-B.

(3) Weighing bismuth nitrate to prepare an acidic solution, immersing the semi-finished catalyst C7-B prepared in the step (2) in the prepared bismuth nitrate solution, shaking, drying at 140 ℃ for 2 hours after the solution is completely absorbed, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst C7-C.

(4) And (3) weighing palladium chloride, dissolving in 70mL of deionized water, adding 30g of normal hexane, adding 80 g of tween, adding 16g of normal amyl alcohol, stirring fully to form microemulsion, immersing the semi-finished catalyst C7-C prepared in the step (3) into the prepared microemulsion, shaking for 90min, filtering out residual liquid, drying at 80 ℃ for 5 hours, and roasting at 500 ℃ for 4 hours to obtain the desired catalyst C7.

The particle size of the microemulsion prepared in the dynamic light scattering measurement steps (1) and (4) is 50nm.

Reduction of the catalyst:

before use, the mixture is placed in a fixed bed reaction device, and is subjected to reduction treatment for 8 hours at the temperature of 150 ℃ by using mixed gas with the molar ratio of N ₂:H₂ =1:1.

Table 1 example catalyst component content

Comparative example 1

Comparative example 1 catalyst D1 was prepared by the same method, composition and reduction treatment as catalyst C1 of example 1, except that Cu was not supported in step (1) of comparative example 1. The preparation steps of the catalyst D1 are as follows:

Nickel microemulsion loading, palladium solution loading, bismuth solution loading and palladium microemulsion loading

All parameters of the preparation procedure were the same as in example 1, to finally prepare catalyst D1 of comparative example 1.

Comparative example 2

The catalyst of comparative example 2 was prepared in the same manner as the catalyst of example 1 except that the catalyst of comparative example 2 was reduced at 350 ℃.

All parameters of the preparation procedure were the same as in example 1, to finally prepare catalyst D2 of comparative example 2.

Comparative example 3

Comparative example 3 catalyst D3 was prepared by the same procedure as catalyst C2 of example 2, except that Cu was solution supported, and catalyst D3 was prepared by the steps of:

Nickel microemulsion loading, palladium solution loading, bismuth copper solution loading

All parameters of the preparation procedure were the same as in example 2, to finally prepare catalyst D3 of comparative example 3.

Comparative example 4

Comparative example 4 catalyst D4 was prepared by the same procedure, composition and reduction treatment as catalyst C2 of example 2, except that bismuth in solution was supported prior to palladium in solution, and catalyst D4 was prepared by the steps of:

nickel copper microemulsion loading, palladium microemulsion loading, bismuth solution loading and palladium solution loading

All parameters of the preparation procedure were the same as in example 2, to finally prepare catalyst D4 of comparative example 4.

Comparative example 5

Comparative example 5 catalyst D5 was prepared and its composition and reduction treatment were the same as those of catalyst C3 of example 3, except that the step of carrying Pd by the microemulsion method was omitted. The preparation steps of the catalyst D4 are as follows:

Palladium solution loading, nickel copper microemulsion loading, bismuth solution loading

All other parameters of the preparation procedure were the same as in example 3, to finally prepare catalyst D5 of comparative example 5.

Comparative example 6

Comparative example 6 catalyst D6 was prepared by the same procedure, composition and reduction treatment as catalyst C3 of example 3, except that the microemulsion palladium, nickel, copper were simultaneously supported, and catalyst D6 was prepared by the following steps:

Palladium solution loading, palladium nickel copper simultaneous microemulsion loading, bismuth solution loading

All other parameters of the preparation procedure were the same as in example 3, and finally comparative example 6 catalyst D6 was prepared.

Comparative example 7

Comparative example 7 catalyst D7 was prepared by the same procedure as in example 4 catalyst C4, except that the microemulsion nickel loading was eliminated, and catalyst D7 was prepared by the following steps:

Copper microemulsion loading, palladium solution loading and bismuth solution loading

All other parameters of the preparation procedure were the same as in example 4, finally obtaining catalyst D7 of comparative example 7.

Comparative example 8

Comparative example 8 catalyst D8 was prepared by the same procedure as in example 5 catalyst C5, except that the preparation steps (3) and (4) were sequentially reversed. The preparation steps of the catalyst D8 are as follows:

Palladium solution loading, bismuth solution loading, palladium microemulsion loading, nickel copper microemulsion loading

All other parameters of the preparation procedure were the same as in example 5, to finally prepare catalyst D8 of comparative example 8.

Comparative example 9

Comparative example 9 catalyst D9 was prepared by the same procedure as catalyst C6 of example 6, except that the microemulsion nickel palladium was first supported and the microemulsion copper was then supported, and the catalyst D9 was prepared by the following steps:

Nickel palladium microemulsion loading, palladium solution loading, bismuth solution loading and copper microemulsion loading

All parameters of the preparation procedure were the same as in example 6, to finally prepare catalyst D9 of comparative example 9.

Comparative example 10

Comparative example 10 catalyst D10 was prepared by the same procedure, composition and reduction treatment as catalyst C7 of example 7, except that the nickel-copper alloy microemulsion prepared in step (1) had a particle size smaller than the small pore maximum diameter, namely:

nickel nitrate and copper nitrate are dissolved in 52g of water, 30g of normal hexane, 17g of tween80 and 16g of normal amyl alcohol are added and fully stirred to form microemulsion, and the particle size of the prepared microemulsion is 36nm by a dynamic light scattering method. Otherwise, catalyst D10 of comparative example 10 was finally obtained in the same manner as in example 7.

Performance of catalyst in butene recovery reaction by acetylene-rich carbon four-fraction selective hydrogenation

The catalyst is filled in a fixed bed sheet section reactor with the loading of 50mL, the filling of 50mL, the mass space velocity of the fresh material for reaction of 1h ^-1, the fresh raw material is diluted by using the residual carbon four, the dilution mass ratio is 20:1, the operating pressure is 2.0MPa, the molar ratio of the sum of the contents of hydrogen and butadiene and carbon tetrayne in the raw material to be hydrogenated is 1.8, and the inlet temperature of the reactor is 45 ℃. The compositions of the reaction materials butadiene and the carbon tetrayne are shown in the table 2 and the table 3.

TABLE 2 reaction mass butadiene and carbon tetraalkyne compositions

TABLE 3 high butadiene and carbon tetraalkyne reaction Material composition

The evaluation results of the catalyst are shown in Table 4, and the main indexes of the evaluation results are mass fraction of butadiene, mass fraction of vinyl acetylene, alkane increment (mass fraction) and coking amount of the catalyst when the catalyst is operated for 500 hours. Catalysts 1,2, 3, 4,5, 6, 7 were derived from examples 1,2, 3, 4,5, 6, 7, respectively, and comparative catalysts 1,2, 3, 4,5, 6, 7, 8, 9, 10 were derived from comparative examples 1,2, 3, 4,5, 6, 7, 8, 9, 10, respectively. Catalysts 1 to 6 and comparative catalysts 1 to 9 were evaluated using the raw materials shown in table 2, and catalyst 7 and comparative catalyst 10 were evaluated using the raw materials shown in table 3.

Table 4 results of catalyst evaluation

As can be seen from the analysis of the evaluation data of the example and the comparative example catalysts in table 4, the catalyst of the present invention is used for the reaction of recovering butene through selective hydrogenation of acetylene-rich carbon four-cut fraction, and under the same process conditions, the catalyst of the present invention shows more excellent coking resistance, and the catalyst activity and selectivity remain high even though the raw material to be hydrogenated contains more acetylene and butadiene.

Claims

1. The alkyne-rich carbon four-fraction selective hydrogenation catalyst is alumina or alumina mainly and has a bimodal pore distribution structure, wherein the pore diameter of small pores is 10-45 nm, the pore diameter of large pores is 80-500 nm, and the specific surface area of the catalyst is 30-80 m ²/g; the method is characterized in that: the catalyst at least contains Pd, bi, ni and Cu, wherein the mass fraction of Pd is 0.15-0.5%, the mass fraction of Ni is 0.5-5.0%, the mass fraction of Bi is 0.05-0.50%, the mass fraction of Cu is 0.5-3.0%, and the sum of the mass fractions of Ni and Cu is 1.0-8.0% based on 100% of the mass of the catalyst; ni, cu and a small part of Pd are loaded by a microemulsion method and distributed in macropores of 80-500 nm of the carrier; bi and most Pd are loaded by a solution method and distributed in pores of 10-45 nm of the carrier, and the amount of Pd loaded by a microemulsion method is 1/200-1/100 of the sum of Ni and Cu mass fractions; the step of loading Pd by the microemulsion method is carried out after the step of loading Ni and Cu by the microemulsion method; the solution method is carried out to load Bi after Pd is carried out by the solution method; other load sequencing is not limited.

2. The acetylene-rich carbon four-cut selective hydrogenation catalyst according to claim 1, wherein the mass fraction of Pd is 0.20 to 0.45%, the mass fraction of Ni is 1.0 to 3.0%, the mass fraction of Bi is 0.10 to 0.40%, the mass fraction of Cu is 1.0 to 2.0%, and the sum of the mass fractions of Ni and Cu is 3.0 to 5.0%, based on 100% of the mass of the catalyst.

3. The alkyne-rich carbon four-cut selective hydrogenation catalyst of claim 1, wherein the microemulsion loading process comprises: dissolving precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion, wherein the oil phase is alkane or cycloalkane, the surfactant is an ionic surfactant and/or a nonionic surfactant, and the cosurfactant is organic alcohol.

4. The alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 3, wherein the microemulsion loading process is adopted, and the oil phase is C6-C8 saturated alkane or cycloalkane; the surfactant is nonionic surfactant; the cosurfactant is C4-C6 alcohol.

5. The alkyne-rich carbon four-fraction selective hydrogenation catalyst of claim 4, wherein the oil phase is cyclohexane, n-hexane; the surfactant is polyethylene glycol octyl phenyl ether or sorbitan monooleate polyoxyethylene ether; the cosurfactant is n-butanol and/or n-amyl alcohol.

6. The alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 1, wherein the carrier Al ₂O₃ is a mixed alpha, theta crystal form, and the alumina content in the catalyst carrier is above 80%.

7. The alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 3, wherein the mass ratio of the aqueous phase to the oil phase in the microemulsion during the preparation process is 2-3, the mass ratio of the surfactant to the oil phase is 0.15-0.6, and the mass ratio of the surfactant to the cosurfactant is 1-1.2.

8. The alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 1, wherein the catalyst preparation process comprises:

(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, controlling the particle size of the microemulsion to be larger than the maximum pore diameter of small pores of a carrier and smaller than the maximum pore diameter of large pores of the carrier, adding the carrier into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying for 1-6 hours at 60-150 ℃, and roasting for 2-8 hours at 300-600 ℃ to obtain a semi-finished catalyst A;

(2) Dissolving Pd precursor salt in water, regulating the pH value to be 1.5-2.5, adding the semi-finished catalyst A into Pd salt solution, soaking and adsorbing for 0.5-4 h, drying at 60-150 ℃ for 1-6 h, and roasting at 400-550 ℃ for 2-6 h to obtain a semi-finished catalyst B;

(3) Carrying out Bi loading by a Bi salt solution saturation impregnation method, precipitating the semi-finished catalyst B for 0.5-2 h after loading Bi, drying at 60-150 ℃ for 1-6 h, and roasting at 500-550 ℃ for 4-6 h to obtain a semi-finished catalyst C;

(4) Dissolving Pd precursor salt in water, adding metered oil phase, surfactant and cosurfactant, stirring fully to form micro emulsion, controlling the particle diameter of the micro emulsion to be larger than the maximum pore diameter of the carrier pores and smaller than the maximum pore diameter of the carrier macropores, adding the semi-finished product C into the prepared micro emulsion, immersing for 0.5-4 hours, filtering out residual liquid, drying for 1-6 hours at 60-150 ℃, and roasting for 2-8 hours at 300-600 ℃ to obtain the required catalyst.

9. The alkyne-rich carbon four cut selective hydrogenation catalyst of claim 1, wherein fresh catalyst is reduced at 150-200 ℃ prior to being put into hydrogenation reaction.