CN114308059A

CN114308059A - Alkyne-rich carbon four-fraction selective hydrogenation catalyst

Info

Publication number: CN114308059A
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: 2022-04-12
Anticipated expiration: 2040-09-28
Also published as: CN114308059B

Abstract

The invention relates to an alkyne-rich carbon four-fraction selective hydrogenation catalyst, wherein a carrier is alumina or mainly alumina and has a bimodal pore distribution structure, wherein the pore diameter of a small pore is 10-45 nm, and the pore diameter of a large pore is 80-500 nm; the catalyst at least contains Pd, Bi, Ni and Cu, wherein the Ni and the Cu are loaded in a micro-emulsion mode, the Bi is loaded in a solution method, the palladium is loaded in two modes of a solution method and a micro-emulsion method, the amount of the Pd loaded in the micro-emulsion method is 1/200-1/100 of the sum of the mass fractions of the Ni and the Cu, and the Ni, the Cu and the Pd loaded in the micro-emulsion method are distributed in macropores of 80-500 nm of a carrier. The specific surface area of the catalyst is 30-80 m²(ii) in terms of/g. The catalyst of the invention is used for treating the alkyne-rich carbon four-fraction and selectively hydrogenating to recover the butylene, can obviously reduce the coking amount in the operation process of the catalyst, prolong the service life of the catalyst, improve 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 a alkyne-rich carbon four-fraction selective hydrogenation catalyst, in particular to a alkyne-rich carbon four-fraction selective hydrogenation butene recovery catalyst with high coking resistance.

Background

The four fractions of the cracking carbon by-product from the ethylene preparation by hydrocarbon pyrolysis usually contain 40-60% by mass of butadiene, which is an important monomer in the synthetic rubber industry. Butadiene is generally extracted from the cracked C.sub.four fraction by solvent extraction methods such as acetonitrile, N-methylpyrrolidinone and dimethylformamide. Because the acetylene hydrocarbon concentration in the extracted C-C fraction is high and the industrial utilization value is not available at present, the C-C fraction can only be burned, but because the acetylene hydrocarbon with high concentration has the danger of decomposition and explosion, the same amount of butadiene needs to be discharged simultaneously when the acetylene hydrocarbon is separated, and the acetylene hydrocarbon needs to be diluted by proper amount of fractions such as butylene and butane to be sent to a torch for burning in the industrial production due to the safety factor. This not only causes a great waste of resources but also pollutes the environment. These factors all lead to the increase of energy consumption of the traditional carbon four-solvent extraction device, the serious loss of carbon four-olefin resources and the deterioration of economy. Due to the influence of factors such as cracking depth, cracking technology and the like, the alkyne content in the cracked carbon four fraction is gradually increased, and more carbon four resources need 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 industrial technology, the limitation on the alkyne content in butadiene is more strict, and the economic efficiency of a butadiene extraction device is deteriorated due to the factors. The discharged carbon tetraalkyne is treated by adopting a selective hydrogenation method, so that the vinylacetylene and butadiene in the discharged carbon tetraalkyne are converted into mono-olefin, the safety risk brought to the operation of a butadiene extraction device due to the discharge of the material can be eliminated, a large amount of mono-olefin can be recycled, and the purposes of changing waste into valuables, saving energy and reducing consumption are achieved.

The acetylene hydrocarbon and butadiene in the C4 fraction are converted into butene by selective hydrogenation by adopting a selective hydrogenation catalyst, and the selective hydrogenation catalyst is an effective utilization way of the acetylene hydrocarbon in the C4 fraction. The catalyst has high hydrogenation activity and selectivity, namely, acetylene hydrocarbon and butadiene can be effectively removed, the loss of butene is reduced as much as possible, and the catalyst has high stability so as to be suitable for long-period operation. The catalyst used for recovering butene by selective hydrogenation of alkyne-rich carbon four 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, the catalyst takes alumina as a carrier, and comprises an active component palladium, an auxiliary agent copper, an auxiliary agent X1 and an auxiliary agent X2, and the catalyst comprises the following components by the total mass of 100 percent: 0.1-0.5% of palladium, 0.1-6% of copper, 10.5-15% of X, 20.5-5% of X, 0-2% of one or more auxiliary metal selected from cobalt, nickel, molybdenum, tungsten, lanthanum, silver, cerium, samarium and neodymium; wherein X1 is selected from IVA element, X2 is selected from alkali metal, alkaline earth metal or mixture thereof. The catalyst is suitable for selective hydrogenation alkyne removal of alkyne-rich residual materials after butadiene extraction, but the pore volume of 5-15 nm in the pore structure of the catalyst accounts for more than 85% of the total pore volume, is not beneficial to mass transfer of a diffusant and coke containing, and has certain limitation.

ZL201010182736.7 discloses a selective hydrogenation method of alkyne and dialkene in olefin material flow, the catalyst is palladium catalyst, and the load of palladium adopts spray method. However, the catalyst preparation process requires irradiation of the palladium catalyst precursor with ionizing radiation and is not suitable for large-scale production applications.

The palladium catalyst is easy to generate polymerization reaction of unsaturated hydrocarbon to generate ' green oil ' in the process of catalyzing alkyne-rich carbon four-selective hydrogenation reaction, and the deposition of macromolecules of the green oil ' on the catalyst not only covers an active center to reduce the activity of the catalyst, but also blocks a pore channel to influence mass transfer. The service life of the catalyst is an important index for evaluating the comprehensive performance of the catalyst, and is also 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 bimodal pore distribution structure, the active component in the catalyst has Pd, Ag, Ni, wherein Pd, Ag uses the aqueous solution dipping method to load, Ni uses the W/O microemulsion dipping method to load. 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 often reaches about 450 ℃, and Pd atoms in a reduced state are easy to gather at the temperature, so that the activity of the catalyst is greatly reduced, the content of active components needs to be increased to compensate the activity loss, and the cost is increased and the selectivity is reduced.

Disclosure of Invention

The invention aims to provide a alkyne-rich carbon four-fraction selective hydrogenation catalyst, and particularly provides a alkyne-rich carbon four-fraction selective hydrogenation butene recovery catalyst with excellent coking resistance, which is used for treating alkyne-rich carbon four-fraction extracted from butadiene such as butane, butene, butadiene, vinyl acetylene and butyne to recover butene, and can improve the resource additional value of alkyne-rich carbon four-fraction and improve the economic benefit of a device.

The acetylene carbon-rich four-fraction selective hydrogenation catalyst has carrier alumina or mainly alumina and double-peak pore distribution structure, and has small pores of 10-45 nm and large pores of 80-500 nm. The catalyst at least contains Pd, Bi, Ni and Cu, wherein the mass fraction of Pd is 0.15-0.5%, and the preferable mass fraction is 0.2-0.45%, based on 100% of the mass of the catalyst; the mass fraction of Ni is 0.50-5.0%, and the preferable mass fraction is 1.0-3.0%; the mass fraction of Bi is 0.05-0.50%, and the preferable mass fraction is 0.10-0.40%; the mass fraction of Cu is 0.5-3.0%, and the preferable mass fraction is 1.0-2.0%; the sum of the mass fractions of Ni and Cu is 1.0-8.0%, and the preferable mass fraction is 3.0-5.0%. Wherein Ni, Cu and a small amount of Pd are loaded in a microemulsion mode, and the particle size of the microemulsion is controlled to be larger than the maximum pore diameter of small pores of the bimodal pore carrier and smaller than the maximum pore diameter of large pores, so that the microemulsion is distributed in the large pores of the carrier; the specific surface area of the catalyst is 30-80 m²/g。

In the catalyst, the selective hydrogenation reaction of the carbon tetraalkyne and the butadiene is carried out in a main active center consisting 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 dipped in the macropores of the carrier in a micro-emulsion mode, and macromolecules such as green oil and the like generated in the reaction easily enter the macropores of the catalyst. The green oil is subjected to saturated hydrogenation on an active center consisting of Cu, Ni and Pd in a large hole, and due to the fact that double bonds are subjected to hydrogenation saturation, the green oil components can not generate polymerization reaction any more or the polymerization reaction rate is greatly reduced, the chain growth reaction is terminated or delayed, compounds with larger molecular weight can not be formed, and the compounds can be easily taken out of a reactor by materials, so that the coking degree of the surface of the catalyst can be greatly reduced, and the regeneration period and the operation life of the catalyst are greatly prolonged.

Most of the palladium is supported by a solution method, preferably a supersaturated impregnation method. The solution containing palladium enters the pores faster due to the siphoning action of the pores, the palladium exists in the form of chloropalladate ions, and the palladium is quickly targeted due to the chemical bonds formed between the ions and hydroxyl groups on the surface of the carrier, so that the faster the solution enters the pores, the faster the loading speed. It is more easily supported in the pores during the impregnation of Pd in the supersaturated impregnation method.

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

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 metallic state, so that the catalyst can have hydrogenation activity. Because high temperature calcination is an activation process during catalyst preparation, the metal salt decomposes to metal oxides, which form clusters, which are typically nano-sized. 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 metallic state, so that the catalyst can have hydrogenation activity. Different oxide reduction temperatures vary, but for nanometer-sized reactive metal components, around 200 ℃ is an important critical temperature beyond which significant agglomeration of the metal particles occurs. Therefore, the reduction temperature of the active component is very important for the hydrogenation catalyst.

The NiO is completely reduced independently, the reduction temperature is generally 450-500 ℃, and the aggregation of Pd is caused at the temperature. Loading Cu with Ni can lower the reduction temperature of Ni because, after the Cu/Ni alloy is formed, its reduction temperature can be lowered to about 350 ℃ compared to the reduction temperature of pure Ni, thus alleviating the agglomeration of Pd during the reduction process.

The inventors have surprisingly found that by supporting a small amount of Pd on the surface of the Ni/Cu alloy, the reduction temperature of Ni can be reduced to 200 ℃ or lower.

The method for controlling the Ni, Cu and Pd to be positioned in the macropores of the catalyst is to load the Ni, Cu and Pd in the form of microemulsion, wherein the grain diameter 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 the macropores. The Ni, Cu and Pd metal salts are contained in the microemulsion, are difficult to enter the pore channels of the carrier with smaller size due to space resistance, and are distributed in the macropores of the carrier. The amount of Pd supported by the microemulsion method is 1/200-1/100 of the sum of mass fractions of Ni and Cu.

The carrier adopted by the invention is required to have a bimodal pore distribution structure, particularly a large pore with the pore diameter of 80-500 nm, and a small pore with the pore diameter of 10-45 nm. The carrier is alumina or mainly alumina, Al₂O₃The crystal form is preferably a mixed crystal form of alpha and theta. The alumina content in the catalyst carrier is preferably above 80%, and the carrier may also contain other metal oxides such as magnesia, titania, etc.

The invention is not particularly limited to the process of loading Ni, Cu and Pd in a microemulsion mode, and Ni, Cu and Pd can be distributed in the macropores of the carrier as long as the particle size of the microemulsion with the size between the maximum pore diameter of the small pores and the maximum pore diameter of the big pores of the carrier can be formed.

The invention also proposes a method, wherein the microemulsion mode loading 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 and/or nonionic surfactant, and the cosurfactant is organic alcohol.

The kind and addition amount of the oil phase, the surfactant and the co-surfactant are not particularly limited in the present invention, and can be determined according to the pore structures 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 organic alcohol, preferably C4-C6 alcohol, more preferably n-butanol and/or n-pentanol.

In the microemulsion, 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 prepared by a preferred preparation process which specifically 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 larger than the maximum pore diameter of a small pore and smaller than the maximum pore diameter of a large pore. And adding the carrier into the prepared microemulsion, dipping for 0.5-4 hours, and filtering out residual liquid. Drying at 60-150 ℃ for 1-6 hours, and roasting at 300-600 ℃ for 2-8 hours. Obtaining a semi-finished product 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 60-150 ℃ for 1-6 h, and roasting at 400-550 ℃ for 2-6 h to obtain a semi-finished catalyst B.

(3) The load of Bi is carried out by a Bi salt solution saturation impregnation method, the semi-finished product catalyst B is carried with Bi and then is precipitated for 0.5-2 h, then is dried for 1-6 h at the temperature of 60-150 ℃, and is roasted for 4-6 h at the temperature of 500-550 ℃. Obtaining a semi-finished product catalyst C.

(4) Dissolving Pd precursor salt in water, adding metered oil phase, surfactant and cosurfactant, fully stirring to form microemulsion, and controlling the particle size of the microemulsion 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 for 1-6 hours at the temperature of 60-150 ℃, and roasting for 2-8 hours at the temperature of 300-600 ℃ to obtain the required catalyst.

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

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

The precursor salts of Ni, Cu, Bi and Pd in the above steps are soluble salts, and can be nitrates, chlorides or other soluble salts thereof.

The catalyst had the following characteristics: at the beginning of the hydrogenation reaction, the selective hydrogenation reaction of the carbotetraalkyne with butadiene occurs mainly on the main active centers in the pores, consisting of Pd and Bi. 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 of the present invention can lower the reduction temperature to below 200 deg.c.

Before the catalyst is put into hydrogenation reaction, the catalyst is reduced at the reduction temperature of 150-200 ℃.

After the catalyst is adopted, even if reactants contain more carbon tetraalkyne and butadiene, the activity and the selectivity of the catalyst still keep high levels, and meanwhile, the coking amount of the catalyst is low.

Drawings

FIG. 1 shows TPR spectra of Cu/Ni alloy and Pd-Cu/Ni alloy.

Detailed Description

The analysis method comprises the following steps:

the catalyst of the invention is prepared by the following analytical characterization methods: analyzing the microemulsion particle size distribution on a dynamic light scattering particle size analyzer; analyzing the specific surface area and the pore diameter of the carrier by GB/T21650; measuring the mass fraction of the catalyst composition by using the general rules of atomic absorption spectrometry GB/T15337 and the general rules of chemical reagent flame atomic absorption spectrometry GB/T19723; the composition of cleaved C4 was determined by 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 spherical alumina carrier with bimodal pore distribution and a diameter of 4mm was used. After roasting for 4 hours at 1020 ℃, the bimodal pore size distribution ranges from 12 nm to 35nm and 80 nm to 400nm, and the specific surface area is 45m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing nickel nitrate and copper chloride, dissolving in 60mL deionized water, adding cyclohexane 20g, adding Triton X-1008 g and n-butanol 7g, stirring thoroughly to form microemulsion, soaking the weighed carrier calcined at high temperature into the prepared microemulsion, shaking for 30min, filtering to remove residual liquid, and washing with deionized water. Drying at 80 deg.C for 6 hr, and calcining at 400 deg.C for 6 hr. Referred to as semi-finished catalyst C1-A.

(2) Preparing palladium chloride into an active component impregnation liquid, adjusting the pH value to 2.0, then impregnating the semi-finished catalyst C1-A into the prepared Pd salt solution, drying for 6 hours at 80 ℃ after impregnating for 30 minutes, and roasting for 4 hours at 500 ℃. To obtain a semi-finished catalyst C1-B.

(3) Weighing bismuth nitrate to prepare an acid solution, soaking the semi-finished catalyst C1-B prepared in the step (2) in the prepared bismuth nitrate solution containing bismuth, 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) Weighing palladium chloride, dissolving in 60mL deionized water, adding cyclohexane 20g, adding Triton X-1008 g and n-butanol 7g, fully stirring to form microemulsion, placing 100g of the weighed semi-finished catalyst C1-C in the prepared microemulsion, shaking for 30min, filtering out residual liquid, and washing with deionized water. Drying at 80 deg.C for 6 hr, and calcining at 400 deg.C for 6 hr. The desired catalyst C1 was obtained.

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

And (3) reduction of the catalyst:

before use, the mixture is placed in a fixed bed reaction device and is mixed with N₂:H₂1:1, and reducing at 200 ℃ for 8 h.

Example 2

Carrier:

a commercially available spherical alumina carrier with bimodal pore distribution and a diameter of 3mm is used. 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 49m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing nickel nitrate and copper chloride, dissolving in 70mL of deionized water, adding 26g of n-hexane, adding tween8010g and adding 9g of n-octanol, fully stirring to form a microemulsion, dipping 100g of the weighed carrier calcined at high temperature into the prepared microemulsion, shaking for 90min, filtering out residual liquid, drying at 100 ℃ for 5 hours, and calcining at 500 ℃ for 4 hours. Referred to as semi-finished catalyst C2-A.

(2) Weighing palladium chloride, dissolving in 70mL of deionized water, adding 26g of n-hexane, adding tween8010g and adding 9g of n-octanol, fully stirring to form a microemulsion, dipping 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 impregnation liquid, adjusting the pH value to 1.8, then impregnating the semi-finished catalyst C2-B prepared in the step (2) into the prepared Pd salt solution, drying for 5 hours at 100 ℃ after impregnating for 60 minutes, and roasting for 6 hours at 400 ℃. Obtaining a semi-finished product catalyst C2-C.

(4) Weighing bismuth nitrate to prepare an acidic solution, soaking the semi-finished catalyst C2-C prepared in the step (3) in the prepared bismuth nitrate solution containing bismuth, 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 micro-emulsion prepared in the steps (1) and (2) is 54nm determined by a dynamic light scattering method.

And (3) reduction of the catalyst:

before use, the mixture is placed in a fixed bed reaction device and is mixed with N₂:H₂1:1 of the mixed gas,

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

Example 3

Carrier:

a commercially available spherical alumina carrier with bimodal pore distribution and a diameter of 4mm was used. After roasting for 4 hours at 1030 ℃, the bimodal pore size distribution ranges from 15 to 45nm and 100 to 500nm, and the specific surface area is 43m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing palladium nitrate, dissolving in deionized water, adjusting pH to 2, soaking 100g of the carrier calcined at high temperature into the prepared Pd salt solution, soaking for 90min, drying at 120 ℃ for 4 hours, and calcining at 500 ℃ for 4 hours. Obtaining a semi-finished product catalyst C3-A.

(2) Weighing nickel nitrate and copper chloride, dissolving in 96mL deionized water, adding cyclohexane 33g, adding Triton X-1008 g and n-butanol 8g, fully stirring to form a microemulsion, dipping the semi-finished catalyst C3-A prepared in the step (1) into the prepared microemulsion, shaking for 240min, filtering out residual liquid, drying at 120 ℃ for 3 hours, and roasting at 600 ℃ for 2 hours. Referred to as semi-finished catalyst C3-B.

(3) Weighing bismuth nitrate to prepare an acid solution, soaking the semi-finished catalyst C3-B prepared in the step (2) in the prepared bismuth nitrate solution containing bismuth, 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) Weighing palladium nitrate, dissolving in 96mL deionized water, adding cyclohexane 33g, adding Triton X-1008 g and n-butanol 8g, fully stirring to form a 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) determining the particle sizes of the microemulsions prepared in the steps (2) and (4) to be 200nm by using a dynamic light scattering method.

And (3) 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 by pure hydrogen at the temperature of 150 ℃.

Example 4

Carrier:

with commercially available bimodal pore distribution spheresThe alumina-titania carrier has titania of 20 wt% and diameter of 3 mm. 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 48m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing nickel chloride and copper nitrate, dissolving in 80mL deionized water, adding 40g of n-heptane, adding tween8020g and 17g of n-pentanol, stirring thoroughly to form microemulsion, soaking 100g of the weighed carrier calcined at high temperature into the prepared microemulsion, shaking for 180min, filtering to remove residual liquid, drying at 80 ℃ for 4 hours, and calcining at 600 ℃ for 2 hours. Referred to as semi-finished catalyst C4-A.

(2) Weighing palladium chloride, dissolving in 80mL deionized water, adding 40g of n-heptane, adding tween8020g and 17g of n-pentanol, fully stirring to form a microemulsion, dipping 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) Weighing palladium chloride, dissolving in deionized water, adjusting the pH value to 2.2, soaking the semi-finished catalyst C4-B prepared in the step (2) into the prepared Pd salt solution for 120min, drying at 130 ℃ for 3 hours, and roasting at 550 ℃ for 2 hours. Obtaining a semi-finished product catalyst C4-C.

(4) Weighing bismuth nitrate to prepare an acid solution, soaking the semi-finished catalyst C4-C prepared in the step (3) in the prepared bismuth nitrate solution containing bismuth, 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.

The particle size of the micro-emulsion prepared in the steps (1) and (2) is 48nm measured by a dynamic light scattering method.

And (3) reduction of the catalyst:

before use, the mixture is placed in a fixed bed reaction device and is mixed with N₂:H₂1:1 at 200 ℃ for 8 h.

Example 5

Carrier:

using a commercially available bimodal pore fractionThe spherical alumina-magnesia carrier is distributed, the mass fraction of the magnesia is 3 percent, and the diameter is 3 mm. After roasting for 4 hours at 1050 ℃, the bimodal pore size distribution ranges from 15 to 40nm and 100 to 450nm, and the specific surface area is 38m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing palladium chloride, dissolving in deionized water, adjusting the pH value to 2.5, then 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 a semi-finished catalyst C5-A.

(2) Weighing bismuth nitrate to prepare an acid solution, soaking the semi-finished catalyst C5-A prepared in the step (1) in the prepared bismuth nitrate solution containing bismuth, 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 n-hexane, 18g of hexadecyl trimethyl ammonium bromide (CTAB) and 16g of n-hexanol, fully stirring 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 of deionized water, adding 42g of n-hexane, 18g of CTAB and 16g of n-hexanol, fully stirring to form a microemulsion, dipping 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 (4) determining the particle sizes of the microemulsions prepared in the steps (3) and (4) to be 65nm by using a dynamic light scattering method.

And (3) reduction of the catalyst:

before use, the mixture is placed in a fixed bed reaction device and is mixed with N₂:H₂Reducing the mixed gas at 180 ℃ for 8h under the condition of 1: 1.

Example 6

Carrier:

using commercially available bimodal pore distribution spheresThe alumina-magnesia carrier is formed, the mass fraction of magnesia is 3 percent, and the diameter is 3 mm. After roasting for 4 hours at 990 ℃, the bimodal pore size distribution ranges from 15 to 40nm and 100 to 450nm, and the specific surface area is 62m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing nickel chloride and copper nitrate, dissolving in 90mL deionized water, adding 42g of n-pentane, 18g of hexadecyl trimethyl ammonium bromide (CTAB) and 16g of n-hexanol, fully stirring to form a microemulsion, soaking 100g of the weighed carrier calcined at high temperature into the prepared microemulsion, shaking for 100min, filtering out residual liquid, drying at 70 ℃ for 6 hours, and calcining at 600 ℃ for 2 hours. Referred to as semi-finished catalyst C6-A.

(2) Weighing palladium chloride, dissolving in deionized water, adjusting 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 a semi-finished catalyst C6-B.

(3) Weighing bismuth nitrate to prepare an acidic solution, soaking the semi-finished catalyst C6-B prepared in the step (2) in the prepared bismuth nitrate solution containing bismuth, 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) Weighing palladium chloride, dissolving in 90mL of deionized water, adding 42g of n-pentane, adding CTAB18g and 16g of n-hexanol, fully stirring to form a microemulsion, dipping 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 hours, and roasting at 600 ℃ for 2 hours. The desired catalyst C6 was obtained.

The particle size of the micro-emulsion prepared in the steps (1) and (4) is 65nm determined by a dynamic light scattering method.

And (3) reduction of the catalyst:

Example 7

Carrier:

using commercially available doubletsThe pores are distributed with spherical alumina carriers with the diameter of 3 mm. After roasting for 4 hours at 1000 ℃, the bimodal pore size distribution ranges from 15 to 45nm and 100 to 400nm, and the specific surface area is 50m²(ii) in terms of/g. 100g of the carrier was weighed.

Preparing a catalyst:

(1) weighing nickel chloride and copper nitrate, dissolving in 70mL of deionized water, adding 30g of n-hexane, adding 30g of tween 8016 g and 16g of n-pentanol, fully stirring to form a microemulsion, soaking 100g of the weighed carrier calcined at high temperature into the prepared microemulsion, shaking for 90min, filtering out residual liquid, drying at 80 ℃ for 5 hours, and calcining at 500 ℃ for 4 hours to obtain the semi-finished catalyst C7-A.

(2) Weighing palladium chloride, dissolving in deionized water, adjusting the pH value to 1.6, then soaking the semi-finished catalyst C7-A in the prepared Pd salt solution, drying at 100 ℃ for 5 hours after soaking for 60 minutes, and roasting at 400 ℃ for 6 hours to obtain the semi-finished catalyst C7-B.

(3) Weighing bismuth nitrate to prepare an acid solution, soaking the semi-finished catalyst C7-B prepared in the step (2) in the prepared bismuth nitrate solution containing bismuth, 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) Weighing palladium chloride, dissolving in 70mL of deionized water, adding 30g of n-hexane, adding 30g of tween 8016 g and 16g of n-pentanol, fully stirring to form a microemulsion, dipping 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 catalyst C7.

Dynamic light scattering measurement the particle size of the microemulsions prepared in steps (1), (4) was 50 nm.

And (3) reduction of the catalyst:

before use, the mixture is placed in a fixed bed reaction device and is mixed with N₂:H₂Reducing the mixed gas at 150 ℃ for 8h under the condition of 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 in 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 → palladium microemulsion loading

Preparation procedure all parameters were the same as in example 1, and catalyst D1 of comparative example 1 was finally obtained.

Comparative example 2

Comparative example 2 the catalyst was prepared by the same method and composition as the catalyst of example 1 except that the reduction temperature of the catalyst of comparative example 2 was 350 c.

Preparation procedure all parameters were the same as in example 1, and catalyst D2 of comparative example 2 was finally obtained.

Comparative example 3

Comparative example 3 catalyst D3 was prepared by the same method, composition and reduction treatment as example 2 catalyst C2 except that Cu was supported by a solution process and catalyst D3 was prepared by the steps of:

nickel microemulsion loading → palladium solution loading → bismuth copper solution loading

Preparation procedure all parameters were the same as in example 2, and catalyst D3 of comparative example 3 was finally obtained.

Comparative example 4

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

nickel-copper microemulsion load → palladium microemulsion load → bismuth solution load → palladium solution load

Preparation procedure all parameters were the same as in example 2, to finally obtain catalyst D4 of comparative example 4.

Comparative example 5

Comparative example 5 catalyst D5 was prepared by the same procedure, composition and reduction as example 3 catalyst C3, except that the step of loading Pd by microemulsion was eliminated. The preparation steps of the catalyst D4 are as follows:

palladium solution load → nickel-copper microemulsion load → bismuth solution load

Preparation procedure all other parameters were the same as in example 3, and catalyst D5 of comparative example 5 was finally obtained.

Comparative example 6

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

palladium solution load → palladium nickel copper simultaneous microemulsion load → bismuth solution load

Preparation procedure all other parameters were the same as in example 3, and catalyst D6 of comparative example 6 was finally obtained.

Comparative example 7

Comparative example 7 the preparation method, composition and reduction treatment of catalyst D7 were the same as those of catalyst C4 of example 4, except that the loading of microemulsion nickel was eliminated, and the catalyst D7 was prepared by the following steps:

copper microemulsion load → palladium solution load → bismuth solution load

Preparation procedure all other parameters were the same as in example 4, to finally obtain catalyst D7 of comparative example 7.

Comparative example 8

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

palladium solution load → bismuth solution load → palladium microemulsion load → nickel copper microemulsion load

Preparation procedure all other parameters were the same as in example 5, to finally obtain catalyst D8 of comparative example 8.

Comparative example 9

Comparative example 9 the preparation method, composition and reduction treatment of catalyst D9 were the same as those of catalyst C6 of example 6, except that the microemulsion method nickel palladium was first loaded, the microemulsion method copper was then loaded, and the preparation of catalyst D9 was carried out by the following steps:

nickel palladium microemulsion load → palladium solution load → bismuth solution load → copper microemulsion load

Preparation procedure all parameters were the same as in example 6 to finally obtain catalyst D9 of comparative example 9.

Comparative example 10

Comparative example 10 catalyst D10 was prepared by the same method, composition and reduction treatment as example 7 catalyst C7, except that the particle size of the nickel-copper alloy micro-emulsion prepared in step (1) was smaller than the maximum pore size of the small pores, i.e.:

dissolving nickel nitrate and copper nitrate in 52g of water, adding 30g of n-hexane, 17g of tween80 and 16g of n-amyl alcohol, fully stirring to form a microemulsion, and determining the particle size of the prepared microemulsion to be 36nm by a dynamic light scattering method. The other procedures were the same as in example 7 to finally obtain catalyst D10 of comparative example 10.

Performance of catalyst applied to selective hydrogenation of alkyne-rich carbon four-fraction for recovering butene

The filling amount of the catalyst in a fixed bed single-stage reactor is 50mL, the filling amount is 50mL, and the mass space velocity of the fresh reaction material is 1h^-1Diluting the fresh raw material by using the raffinate C4, wherein the dilution mass ratio is 20:1, the operating pressure is 2.0MPa, the molar ratio of the hydrogen to the butadiene and C-tetraalkyne content 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 C-tetraalkyne are shown in Table 2 and Table 3.

TABLE 2 reaction materials butadiene and C-tetraalkyne compositions

TABLE 3 high butadiene and carbotetraalkyne reaction Material composition

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

TABLE 4 catalyst evaluation results

As can be seen from the evaluation data analysis of the examples and the comparative catalyst in the table 4, the catalyst of the invention is used for the butene recovery reaction of acetylene-rich carbon four-fraction selective hydrogenation, and under the same process conditions, the catalyst of the invention shows more excellent anti-coking performance, and even if the raw material to be hydrogenated contains more acetylene hydrocarbon and butadiene, the activity and the selectivity of the catalyst still keep higher levels.

Claims

1. The acetylene carbon-rich four-fraction selective hydrogenation catalyst has a carrier of alumina or mainly alumina and a bimodal pore distribution structure, wherein the pore diameter of a small pore is 10-45 nm, the pore diameter of a large pore is 80-500 nm, and the specific surface area of the catalyst is 30-80 m²(ii)/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%; ni, Cu and a small part of Pd are loaded by a micro-emulsion method and distributed in macropores of 80-500 nm of a 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 mass fractions of Ni and Cu.

2. The selective hydrogenation catalyst for the alkyne-rich carbon four-fraction as recited in claim 1, wherein the mass fraction of Pd is 0.20-0.45%, the mass fraction of Ni is 1.0-3.0%, the mass fraction of Bi is 0.10-0.40%, the mass fraction of Cu is 1.0-2.0%, and the sum of the mass fractions of Ni and Cu is 3.0-5.0%, based on 100% by mass of the catalyst.

3. The alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 1, wherein the microemulsion loading process comprises: 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 and/or nonionic surfactant, and the cosurfactant is organic alcohol.

4. An alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 1 or 3, wherein a microemulsion loading process is adopted, and an oil phase is C6-C8 saturated alkane or cycloalkane, preferably cyclohexane and n-hexane; the surfactant is nonionic surfactant, preferably polyoxyethylene octyl phenyl ether or sorbitan monooleate polyoxyethylene ether; the cosurfactant is C4-C6 alcohol, preferably n-butanol and/or n-pentanol.

5. The alkyne-rich carbon four-fraction selective hydrogenation catalyst as recited in claim 1, wherein the step of loading Pd by microemulsion method is after the step of loading Ni and Cu by microemulsion method; loading Bi by a solution method after loading Pd by the solution method; the other load precedence order is not limited.

6. The alkyne-rich carbon tetradistillate selective hydrogenation catalyst of claim 1, wherein the support Al₂O₃The crystal form is alpha and theta mixed crystal form, and the content of alumina in the catalyst carrier is more than 80%.

7. The alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 1 or 3, wherein the mass ratio of the water phase to the oil phase in the microemulsion in 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 tetradistillate selective hydrogenation catalyst of claim 1, wherein the catalyst preparation method 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 the temperature of 60-150 ℃, and roasting for 2-8 hours at the temperature of 300-600 ℃ to obtain a semi-finished product 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 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, after carrying Bi on the semi-finished product catalyst B, precipitating for 0.5-2 h, drying for 1-6 h at 60-150 ℃, roasting at 500-550 ℃ for 4-6 h to obtain a semi-finished product catalyst C;

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

9. The alkyne-rich carbon four-fraction selective hydrogenation catalyst according to claim 1, wherein the catalyst is reduced at 150-200 ℃ before being put into hydrogenation reaction by fresh catalyst.