CN117160473A

CN117160473A - Preparation method of high-coking-resistance alkyne-removal catalyst

Info

Publication number: CN117160473A
Application number: CN202210593442.6A
Authority: CN
Inventors: 苟尕莲; 温翯; 薛文利; 王涛; 张峰; 车春霞; 韩伟; 梁玉龙; 边虎
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2023-12-05

Abstract

The invention relates to a preparation method of a high anti-coking acetylene removal catalyst, in particular to a preparation method of a selective hydrogenation catalyst for preparing olefin by ethane pyrolysis. The catalyst prepared by the method adopts alumina or alumina mainly as a carrier, has a bimodal pore distribution structure and at least contains Pd, fe, co, ni, cu. Wherein the active component Pd is loaded in two ways of solution and microemulsion; fe. Co is loaded by a solution method, and Pd loaded by the solution method is mainly distributed in pores of 40-75 nm of the carrier; ni and Cu are loaded by adopting a microemulsion impregnation method, and Pd loaded by adopting an emulsion method is mainly distributed in macropores of 200-650 nm of the carrier, and Pd loaded by adopting the microemulsion method is loaded after Ni and Cu. The catalyst prepared by the method has the advantages of lower reduction temperature, low green oil production, excellent catalytic performance and coking resistance and low production cost.

Description

Preparation method of high-coking-resistance alkyne-removal catalyst

Technical Field

The invention relates to a preparation method of a high-coking-resistance alkyne-removal catalyst, in particular to a preparation method of a high-coking-resistance hydrogenation catalyst for preparing olefin by ethane pyrolysis.

Background

The low-carbon olefin such as ethylene, propylene and the like is an important basic chemical raw material, and along with the development of national economy in China, particularly the development of modern chemical industry, the demand for the low-carbon olefin is gradually increased, and the contradiction between supply and demand is also increasingly outstanding. So far, the important way to prepare low-carbon olefins such as ethylene, propylene and the like is still to prepare the low-carbon olefins by catalytic cracking of naphtha and light diesel (all from petroleum), and the important way to prepare the raw material resources such as naphtha, light diesel and the like as raw materials for producing ethylene is faced with the increasingly serious shortage situation. In addition, in recent years, the imported crude oil in China accounts for about half of the total processing amount, and polyolefin products taking ethylene and propylene as raw materials still maintain quite high imported proportion. Therefore, the development of non-petroleum resources for producing lower olefins is becoming increasingly important.

At present, three main raw materials for producing ethylene at home and abroad are: petroleum, coal, and ethane. The petroleum route adopts the naphtha cracking method, so that the petroleum route has the advantages of heavy raw material structure, high production cost and high dependence on petroleum resources. The production of Chinese ethylene mainly uses naphtha as raw material, and its cost is higher than that of ethylene produced by North America and middle east using cheap ethane as raw material. Compared with naphtha, the ethane cracking has low methane, propylene and butadiene yields and high ethylene yields. Of all conventional cracking feedstocks, the ethylene yield in the ethane cracking product is highest, the methane yield is lowest, meaning that the energy consumption of the separation device is relatively low, and methane is typically used as fuel, with the lowest economic value. Thus, for ethylene products, ethane is the best cracking raw material, and has the advantages of high ethylene yield, short process flow, low device investment and little pollution. By the end of 2018, 15 ethane cracking ethylene production projects are being constructed and planned in China, and the total capacity is about 1980 ten thousand tons/year, as shown in Table 1. The Chinese petroleum is designed to be an ethane pyrolysis ethylene making device 2 sets (Tarim 60 ten thousand tons/year, changqing 80 ten thousand tons/year).

TABLE 1 construction planning conditions for ethylene production project by Chinese ethane pyrolysis

Ethane cracking rationale:

steam cracking is the most widely used process for producing ethylene. The main reaction is simpler [ as shown in formula (1) ] and ethane is dehydrogenated at 850 ℃ and 70kPa to generate ethylene and byproduct hydrogen. Other major products during the reaction include methane, acetylene, propylene, propane, butadiene and other hydrocarbons.

C ₂ H ₆ →C ₂ H ₄ +H ₂ (1)

2C ₂ H ₆ →C ₃ H ₈ +CH ₄ (2)

C ₃ H ₈ →C ₃ H ₆ +H ₂ (3)

C ₃ H ₈ →C ₂ H ₄ +CH ₄ (4)

C ₃ H ₆ →C ₂ H ₂ +CH ₄ (5)

C ₂ H ₂ +C ₂ H ₄ →C ₄ H ₆ (6)

2C ₂ H ₆ →C ₂ H ₄ +2CH ₄ (7)

C ₂ H ₆ +C ₂ H ₄ →C ₃ H ₆ +CH ₄ (8)

After alkaline washing and dehydration, the pyrolysis gas is treated by a demethanizer, and the ethylene material at the top of the deethanizer still contains 0.15-0.3% of acetylene, and the acetylene can be taken as a production raw material of polymerization-grade ethylene after being removed to below 1ppm by selective hydrogenation.

At present, the selection and removal of trace acetylene in ethylene materials in an olefin production device by ethane pyrolysis mainly adopts a two-section reactor series process (the composition of raw materials is shown in table 2). The reaction pressure is 1.5-3.0 MPa, and the airspeed is 6000-14000 h ^-1 The inlet temperature is 50-90 ℃.

TABLE 2 composition of carbon dioxide hydrogenation feedstock for producing olefins by ethane pyrolysis

Hydrogenation raw material	H ₂	C ₂ H ₂	C ₂ H ₄	CH ₄	CO
						Content (phi%)	5～15	0.15～0.3	70～80	5～20	0.02～0.2

Alkyne and diene selective hydrogenation catalysts are obtained by supporting noble metals such as palladium on a porous inorganic support (US 4762956). In order to increase the selectivity of the catalyst and reduce the deactivation of the catalyst caused by green oil produced by oligomerization during hydrogenation, the prior art has employed a method of adding, for example, a group IB element to the catalyst as a co-catalytic component: pd-Au (US 4490481), pd-Ag (US 4404124), pd-Cu (US 3912789), or alkali metal or alkaline earth metal (US 5488024) is added, and alumina, silica (US 5856262), honeycomb-like bluestone (CN 1176291) or the like is used as a carrier. The patent US4404124 prepares a selective hydrogenation catalyst with active component palladium shell distribution by a step-by-step impregnation method, and can be applied to selective hydrogenation of carbon two and carbon three fractions so as to eliminate acetylene in ethylene and propyne and propadiene in propylene. US5587348 uses alumina as a carrier, adjusts the action of promoter silver and palladium, and adds alkali metal and chemically bonded fluorine to prepare the carbon hydrogenation catalyst with excellent performance. The catalyst has the characteristics of reducing green oil generation, improving ethylene selectivity and reducing the generation amount of oxygen-containing compounds. US5519566 discloses a method for preparing a silver and palladium catalyst by wet reduction, wherein an organic or inorganic reducing agent is added into an impregnating solution to prepare a silver and palladium two-component selective hydrogenation catalyst.

The traditional carbon two hydrogenation catalysts are prepared by adopting an impregnation method, and the active phases of the catalyst are Pd and Ag bimetallic. This method has the following disadvantages: (1) The dispersion of the active component can not be accurately controlled and the randomness is strong under the influence of the pore structure of the carrier. (2) Under the influence of the surface tension and solvation effect of the impregnating solution, the precursor of the metal active component is deposited on the surface of the carrier in an aggregate form, and uniform distribution cannot be formed. (3) The selectivity requirement of the carbon two hydrogenation on the catalyst is higher, and the traditional preparation method promotes the exertion of the auxiliary agent effect by increasing the amount of Ag, so that the transmission of hydrogen is blocked, the possibility of oligomerization is increased, the green oil generation amount is increased, and the service life of the catalyst is influenced. The occurrence of the three phenomena easily causes poor dispersibility of the metal active components, low reaction selectivity and high green oil yield, thereby affecting the overall performance of the catalyst. (4) the catalyst has high production cost and weak market competitiveness.

CN201110086174.0 forms a polymer coating layer on the surface of a carrier by adsorbing a specific polymer compound on the carrier, and reacts with the polymer by using a compound with a functional group, so that the compound has a functional group capable of complexing with an active component, and the active component is subjected to a complexing reaction on the functional group on the surface of the carrier, thereby ensuring the ordered and high dispersion of the active component. By adopting the patent method, the carrier adsorbs a specific high molecular compound, and the hydroxyl groups of the alumina are subjected to chemical adsorption, so that the amount of the carrier adsorbed the high molecular compound is limited by the hydroxyl groups of the alumina; the complexation of the functionalized polymer and Pd is not strong, the loading amount of the active component sometimes does not meet the requirement, and part of the active component is remained in the impregnating solution, so that the cost of the catalyst is increased.

In order to improve the anti-coking performance of the catalyst and reduce the surface coking degree of the catalyst, a carbon two-selective hydrogenation catalyst adopting a bimodal pore carrier and a microemulsion preparation method to load active components and a preparation method thereof are disclosed in recent years. The selective hydrogenation catalyst disclosed in patent ZL201310114077.7 is mainly alumina and has a bimodal pore distribution structure, wherein the pore diameter of small pores is within 50nm, and the pore diameter of large pores is 60-800 nm. Based on the mass of the catalyst as 100%, the catalyst contains 0.01 to 0.5 weight percent of Pd, is distributed in a shell layer and has the thickness of 1 to 500um; the Ni-containing anti-coking component Ni is controlled to have a particle size larger than that of small holes of the carrier by a microemulsion method, so that the Ni is mainly distributed in the large holes of the carrier. Patent ZL201310114079.6 discloses a preparation method of a hydrogenation catalyst, wherein a catalyst carrier is mainly alumina and has a bimodal pore distribution structure. The catalyst contains Pd and Ni double active components, and the active component Pd is mainly distributed on the surface of a carrier, particularly in small holes, by making the anti-coking component Ni enter the carrier macropores in the form of microemulsion when preparing the catalyst. Patent ZL201310114371.8 discloses a carbon two-fraction selective hydrogenation method suitable for a pre-depropanization pre-hydrogenation process. The selective hydrogenation catalyst adopted by the method is alumina or alumina mainly, has a bimodal pore distribution structure, contains double active components Pd and Ni, and has an anti-coking component Ni mainly distributed in macropores. The method improves the coking resistance of the catalyst, but the reduction temperature of the single-component Ni in the macropores of the catalyst carrier reaches more than 500 ℃, and the single-component Ni is reduced at the reduction temperature, so that the active component Pd of the catalyst is aggregated, and the activity of the catalyst is greatly reduced. To compensate for the loss of catalyst activity, the amount of active component is increased, which results in a decrease in catalyst selectivity and a decrease in active component utilization.

The active components of the catalyst disclosed in CN106927993A at least contain Fe and Cu, and Cu is considered to be added into the active composition containing iron, so that the activation temperature is reduced, the formation and dispersion of an activated phase of the catalyst are facilitated, and the selectivity of the catalyst is improved. Meanwhile, the addition of Cu is beneficial to the adsorption and activation of alkyne and the improvement of the activity of the catalyst. The roasting temperature is preferably 300-400 ℃; the reduction is carried out at 260-330 ℃. Although the above method has a relatively low reduction temperature, it causes partial agglomeration of metal active components including Pd, fe, zn, etc., and affects catalytic activity.

Disclosure of Invention

The invention aims to provide a preparation method of a high-coking-resistance acetylene removal catalyst, in particular to a preparation method of a trace acetylene selective hydrogenation catalyst in a product of preparing olefin by ethane pyrolysis.

In order to achieve the above purpose, the invention provides a preparation method of a high anti-coking alkyne-removing catalyst, which comprises the following steps:

the catalyst is characterized in that the active component Pd is loaded in two modes of solution and microemulsion; fe. CO is loaded by a solution method, and Pd loaded by the solution method is mainly distributed in small holes of the carrier; ni and Cu are loaded by adopting a microemulsion impregnation method, and Pd loaded by microemulsion is mainly distributed in macropores of the carrier.

In the catalyst of the present invention, the carrier is required to have a bimodal pore distribution structure, the present invention is not particularly limited to the distribution range of macropores and pinholes of the bimodal pore distribution, and can be selected according to the reaction characteristics, such as raw materials, process conditions, active components of the catalyst, etc., and the carrier is particularly recommended to be alumina or mainly alumina, and has a bimodal pore distribution structure, wherein the pore diameter of the micropores is 40-75 nm, and the pore diameter of the macropores is 200-650 nm. The specific surface area of the catalyst is 3-15 m ² Preferably 5 to 10m ² /g。

In the invention, the types and the contents of the active components of the catalyst can be selected according to the reaction characteristics, such as raw materials, process conditions and the like, and the particularly recommended catalyst at least contains Fe, co, pd, ni, cu, wherein Fe and Co are loaded in a solution mode, pd is loaded in a microemulsion mode and a solution mode, and Ni and Cu are loaded in a microemulsion mode; based on the mass of the catalyst being 100%, the content of Fe is 0.5-6.0%, the content of Co is 0.5-3.0%, the content of Pd carried by the solution is 0.005-0.015%, the content of Ni is 0.5-8.0%, the weight ratio of Cu to Ni is 0.1-0.9, and the content of Pd carried by the microemulsion is 1/10-1/5 of the content of Pd carried by the solution method. Wherein Ni, cu and Pd loaded by the microemulsion are mainly distributed in macropores of 200-650 nm of the carrier.

The catalyst at least contains Fe, co, pd, ni, cu, the selective hydrogenation reaction of alkyne occurs in a reaction center composed of Fe, co and Pd, wherein Fe is a main active component of the catalyst and acts to adsorb and activate acetylene so as to catalyze the selective hydrogenation of acetylene; the bimetallic nano particles formed by Co and Fe can further improve the hydrogenation activity of Fe due to the electronic synergistic effect of the alloy, and the hydrogenation starting temperature of Fe can be reduced by 80-100 ℃; the small amount of Pd loaded on the solution is an auxiliary active component of the catalyst, which is favorable for the rapid dissociation of hydrogen, thereby improving the catalytic performance. Because the catalyst is different from the traditional Pd-based industrial hydrogenation catalyst, the non-noble metal Fe is adopted as the main active component, the noble metal Pd is used as the auxiliary active component, the content of the noble metal Pd is low, the dosage of the noble metal Pd is greatly reduced, and the preparation cost of the catalyst is reduced.

In the catalyst, the selective hydrogenation reaction of acetylene mainly occurs in a main active center composed of Fe and Co loaded by a solution; ni and Cu are immersed in macropores of a carrier in the form of microemulsion, and green oil generated in the reaction is subjected to saturated hydrogenation on an active center composed of Cu and Ni.

The Cu has the function of forming Ni/Cu alloy in the roasting process, effectively reducing the reduction temperature of nickel in the reduction process, reducing the polymerization of Fe, co and Pd at high temperature, improving the dispersity of main active components, and simultaneously modulating the saturated hydrogenation reaction performance of Ni in macropores.

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 the catalyst preparation process is an elevated temperature calcination process in which the metal salt decomposes to metal oxides which form clusters, which are typically nano-sized. Different oxides, due to their different chemical properties, need to be reduced at different temperatures. However, for nano-sized metals, a critical temperature of about 200 ℃ is an important critical temperature beyond which metal particles can aggregate quite significantly. Therefore, reducing the reduction temperature of the active component is of great importance for hydrogenation catalysts.

The invention solves the problems of catalyst coking by the following steps:

alkyne selective hydrogenation reaction occurs in main active centers of components, such as Pd, fe, co, macromolecules such as green oil produced in the reaction, and the like, and easily enter macropores of the catalyst. In the macroporous catalyst, ni/Cu component is loaded, wherein Ni has saturated hydrogenation function, and green oil component can generate saturated hydrogenation reaction in active center of Ni/Cu component. Because the double bond is saturated by hydrogenation, the green oil component can not undergo polymerization reaction or greatly reduce the polymerization reaction rate, the chain growth reaction is terminated or delayed, a huge molecular weight condensed ring compound can not be formed, and the condensed ring compound is easily carried out of the reactor by materials, so that the coking degree of the surface of the catalyst can be greatly reduced, and the service life of the catalyst can be greatly prolonged.

The method for controlling the Ni/Cu alloy to be positioned in the macropores of the catalyst is that Ni/Cu is loaded in the form of microemulsion, and the particle size of the microemulsion is larger than the pore diameter of the micropores of the carrier and smaller than the maximum pore diameter of the macropores. Nickel and copper metal salts are contained in microemulsions and, due to steric drag, are difficult to access into the pores of smaller size supports and thus mainly into the macropores of the support.

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

In the invention, a small amount of Pd loaded on the microemulsion is on the surface of the Ni/Cu alloy, so that the reduction temperature of Ni can be further reduced to below 200 ℃ and at least 150 ℃.

In the invention, in the process of loading palladium, iron and cobalt by a solution method, the solution containing palladium and iron enters the pores more quickly due to the siphoning effect of the pores, and the palladium, iron and cobalt exist in the form of ions. So that Pd, fe and Co are more easily loaded in the pores during the impregnation process by the solution method.

In the invention, pd is loaded by adopting two modes of a solution method and a microemulsion method, namely, most Pd is loaded by adopting a solution, and the Pd solution is recommended to adopt a supersaturation impregnation method; and (3) loading a small part of Pd in a microemulsion mode, wherein the particle size of the microemulsion is controlled to be more than 75nm and less than 650nm when the microemulsion is loaded, so that the part of Pd is distributed in macropores of the carrier, and the step of loading the Pd in the microemulsion is performed after the step of loading the Ni and the Cu in the microemulsion.

In the invention, the carrier is required to have a bimodal pore distribution structure, the pore diameter of the macropores is 200-650 nm, and the pore diameter of the micropores is 40-75 nm. The carrier is alumina or mainly alumina, and the crystal forms of the alumina are preferably alpha, theta or mixed crystal forms thereof. The alumina content of the catalyst support is preferably 80wt% or more, and other metal oxides such as magnesium oxide, titanium oxide, etc. may be contained in the support.

In the present invention, the loading of Fe and Co may be performed by a solution supersaturation impregnation method, and the present invention is not particularly limited to the order of loading of Fe and Co by a solution method and loading of Pd, and loading of Fe and Co by a solution method may be performed after or before loading Pd by a solution method.

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 larger than 75nm and smaller than 650nm. The sequence of loading the Pd solution method and the Ni/Cu microemulsion is not limited, and the loading of the Pd solution method can be carried out before or after the loading of the Ni/Cu microemulsion.

The present invention is not particularly limited to the process of loading the microemulsion, and the recommended process of loading the microemulsion includes: 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.

In the invention, the weight ratio of the water phase to the oil phase is 4.5-6.0, the weight ratio of the surfactant to the oil phase is 0.10-0.35, and the weight ratio of the surfactant to the cosurfactant is 1.0-1.2.

The invention also provides a preparation method of the catalyst, which specifically comprises the following steps:

(1) Preparing Pd into active component impregnating solution, regulating pH to 1.8-2.8, adding a carrier into the Pd active component impregnating solution, impregnating and adsorbing for 0.5-4 h, drying for 1-4 h at 100-120 ℃, and roasting for 2-6 h at 400-550 ℃ to obtain a semi-finished catalyst A;

(2) Dissolving precursor salts of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; controlling the particle size of the microemulsion to be larger than the pore diameter of the carrier small pore and smaller than the pore diameter of the carrier large pore; adding the semi-finished catalyst A into the prepared microemulsion, soaking for 0.5-4 h, filtering out residual liquid, drying for 1-6 h at 80-120 ℃, and roasting for 2-8 h at 400-600 ℃; obtaining a semi-finished catalyst B;

(3) The loading of Fe and Co is carried out by a supersaturation impregnation method, namely, the prepared mixed solution of ferric chloride and cobalt chloride is 80-110% of the saturated water absorption rate of the carrier, the semi-finished catalyst B is subjected to precipitation for 0.5-2 h after being loaded with Fe and Co, and then is dried for 1-4 h at 100-120 ℃, and is baked for 4-6 h at 400-550 ℃ to obtain a semi-finished 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 more than 75nm and less than 650nm, adding the semi-finished catalyst C into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 400-600 ℃ to obtain the catalyst.

Alternatively, the preparation method of the catalyst specifically comprises the following steps:

(1) Dissolving precursor salts of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion, wherein the particle size of the microemulsion is controlled to be more than 75nm and less than 650nm; adding the carrier into the prepared microemulsion, soaking for 0.5-4 hours, filtering residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 300-600 ℃. Obtaining 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 for 1-4 h at 80-120 ℃, and roasting for 2-6 h at 400-550 ℃ to obtain a semi-finished catalyst B;

(3) The loading of Fe and Co is carried out by a supersaturation impregnation method, namely, the prepared mixed solution of ferric salt and cobalt salt is 80-110% of the saturated water absorption rate of the carrier, the pH value is adjusted to be 1-5, and the semi-finished catalyst B is roasted at 500-550 ℃ for 4-6 hours after the Fe and Co are loaded, so as to obtain the semi-finished catalyst C;

(4) Dissolving Pd precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion, wherein the particle size of the microemulsion is controlled to be more than 75nm and less than 650nm; adding the semi-finished catalyst C into the prepared microemulsion, soaking for 0.5-4 hours, and filtering out residual liquid; drying at 80-120 deg.c for 1-6 hr and roasting at 300-600 deg.c for 2-8 hr to obtain the 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, fe, co and Pd described in the above steps are soluble salts, and may be nitrate salts, chloride salts or other soluble salts thereof.

The reduction temperature of the catalyst of the present invention is preferably 150 to 200 ℃.

The preparation method of the invention greatly reduces the use level of palladium, even more than 50%. The catalyst prepared using the process of the present invention has the following characteristics: at the beginning of the hydrogenation reaction, the selective hydrogenation reaction of acetylene mainly occurs in the active centers of Fe, co and Pd loaded 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 prepared by the method can greatly reduce the reduction temperature of the catalyst to 150-200 ℃ at the lowest, reduce the agglomeration of active components in the reduction process, and has the advantages that compared with the traditional catalyst, the initial activity, the selectivity and the coking resistance of the catalyst prepared by the method are obviously improved, and the production cost is reduced by more than 20%.

The catalyst prepared by the method has the advantages that the green oil production amount of the catalyst is greatly increased, and the activity and selectivity of the catalyst are not reduced even if the raw materials contain more heavy fractions.

Detailed Description

The analytical test method comprises the following steps:

the ratio table: GB/T-5816;

pore volume: GB/T-5816;

the catalyst contains active components: atomic absorption;

microemulsion particle size distribution of Ni/Cu alloy: a dynamic light scattering particle size analyzer, on an M286572 dynamic light scattering analyzer;

the conversion and selectivity in the examples were calculated according to the following formulas:

acetylene conversion (%) =100× delta acetylene/inlet acetylene content

Ethylene selectivity (%) =100×Δethylene/Δacetylene

Example 1

And (3) a carrier: the commercial bimodal pore distribution spherical alumina carrier with the diameter of 4mm is adopted, and the mixture is roasted for 4 hours at high temperature, and 100g of the mixture is weighed. The calcination temperature and the physical properties of the carrier are shown in Table 3.

And (3) preparing a catalyst:

(1) And (3) weighing nickel nitrate and copper chloride, dissolving in deionized water, adding cyclohexane, tritonX-100 and n-hexanol, and fully stirring to form microemulsion. The carrier is added into the prepared microemulsion to be immersed for 1 hour, then washed to be neutral by deionized water, dried for 2 hours at 120 ℃, and baked for 5 hours at 550 ℃. To obtain a semi-finished catalyst A.

(2) Palladium nitrate is weighed and dissolved in water, and cyclohexane TritonX-1006.03g of n-hexanol is added and fully stirred to form a microemulsion. And (3) adding the semi-finished catalyst A into the prepared microemulsion, soaking for 4 hours, washing with deionized water to neutrality, drying at 90 ℃ for 4 hours, and roasting at 600 ℃ for 2 hours to obtain the semi-finished catalyst B.

(3) And (3) weighing palladium nitrate salt, dissolving in water, adjusting the pH value to be 2, adding the semi-finished catalyst B into a Pd salt solution, soaking and adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 450 ℃ for 6h to obtain the semi-finished catalyst C.

(4) Weighing a certain amount of ferric chloride and cobalt chloride, dissolving in deionized water, immersing the semi-finished catalyst C in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the finished catalyst.

The particle size of the microemulsion prepared in the catalyst preparation process and the content of each component in the catalyst are shown in table 4.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of 1:1, at 160 ℃, reduction treatment for 12h.

The composition of the raw materials and the evaluation results are shown in Table 5 and Table 6, respectively.

Comparative example 1

Unlike example 1:

the microemulsion method only loads Ni, and does not load Cu.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of =1:1, at 500 ℃, reduction treatment is carried out for 12h.

Example 2

And (3) a carrier: adopts a commercial bimodal pore distribution spherical carrier with the diameter of 4mm, and the composition of the carrier is 90 percent of alumina and 10 percent of titanium oxide. After 4 hours of high temperature roasting, 100g of the carrier is weighed, and physical properties of the carrier are shown in Table 3.

And (3) preparing a catalyst:

(2) Palladium nitrate is weighed and dissolved in water, cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. And (3) adding the semi-finished catalyst A into the prepared microemulsion, soaking for 4 hours, washing with deionized water to neutrality, drying at 90 ℃ for 4 hours, and roasting at 600 ℃ for 2 hours to obtain the semi-finished catalyst B.

(4) Weighing ferric chloride and cobalt chloride, dissolving in deionized water, immersing the semi-finished catalyst C in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the finished catalyst.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of 1:1, at 180 ℃, reduction treatment is carried out for 12h.

Comparative example 2

Unlike example 2:

the solution loading method only loads Pd and Co, and does not load Fe.

Example 3

And (3) a carrier: a commercially available bimodal pore distribution spherical alumina carrier was used, 4mm in diameter. After 4 hours of high temperature calcination, 100g of the carrier is weighed, and physical indexes are shown in Table 3.

And (3) preparing a catalyst:

(1) And (3) weighing palladium nitrate salt, dissolving in water, adjusting the pH to be 2, adding the carrier into a Pd salt solution, soaking and adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 450 ℃ for 6h to obtain the semi-finished catalyst A.

(2) Weighing ferric chloride and cobalt chloride, dissolving in deionized water, immersing the semi-finished catalyst A in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst B.

(3) Nickel nitrate and copper chloride are weighed and dissolved in water, cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The semi-finished catalyst B is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Semi-finished catalyst C is obtained.

(4) Palladium nitrate is weighed and dissolved in water, and cyclohexane TritonX-1006.03g of n-hexanol is added and fully stirred to form a microemulsion. The semi-finished catalyst C is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Obtaining the finished catalyst.

Comparative example 3

Unlike example 3:

the microemulsion method only loads Cu and does not load Ni.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of =1:1, at 450 ℃, reduction treatment is carried out for 12h.

Example 4

And (3) a carrier: a commercially available bimodal pore distribution spherical alumina carrier was used, 4mm in diameter. After 4 hours of high temperature calcination, 100g of the carrier is weighed, and physical indexes are shown in Table 1.

And (3) preparing a catalyst:

(1) Nickel nitrate and copper chloride are weighed and dissolved in water, cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The carrier is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. To obtain a semi-finished catalyst A.

(2) And (3) weighing palladium nitrate salt, dissolving in water, adjusting the pH value to be 2, adding the semi-finished catalyst A into a Pd salt solution, soaking and adsorbing for 1h, drying at 110 ℃ for 2h, and roasting at 450 ℃ for 6h to obtain the semi-finished catalyst B.

(3) Weighing ferric chloride and cobalt chloride, dissolving in deionized water, immersing the semi-finished catalyst B in the prepared solution, drying at 110 ℃ for 3 hours, and roasting at 500 ℃ for 4 hours to obtain the semi-finished catalyst C.

(4) Palladium nitrate is weighed and dissolved in water, cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The semi-finished catalyst C is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Obtaining the finished catalyst.

The particle size of the microemulsion prepared in the catalyst preparation process and the content of each component in the catalyst are shown in table 2.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of 1:1, at 170 ℃, reduction treatment for 12h.

Comparative example 4

Unlike example 4:

no solution process was carried Pd.

Example 5

And (3) preparing a catalyst:

(1) Nickel nitrate and copper chloride are weighed and dissolved in water, and cyclohexane TritonX-1006.03g of n-hexanol is added and fully stirred to form microemulsion. The carrier is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. To obtain a semi-finished catalyst A.

(2) Palladium nitrate is weighed and dissolved in water, cyclohexane, tritonX-100 and 6.03g of n-hexanol are added and fully stirred to form microemulsion. The semi-finished catalyst A is added into the prepared microemulsion to be immersed for 4 hours, then washed to be neutral by deionized water, dried for 4 hours at 90 ℃, and baked for 2 hours at 600 ℃. Semi-finished catalyst B was obtained.

Before use, the mixture is placed in a fixed bed reaction device, and the molar ratio is N ₂ :H ₂ Mixed gas of 1:1, at 150 ℃, reduction treatment for 12h.

Comparative example 5

Unlike example 5:

the microemulsion method only loads Ni and Cu, and does not load Pd.

Example 6

And (3) preparing a catalyst:

Comparative example 6

Unlike example 6:

the solution loading method only loads Fe and Pd, and does not load Co.

TABLE 3 physical Properties of catalyst support of examples and comparative examples

	Firing temperature (. Degree. C.)	Pore diameter (nm)	Macropore aperture (nm)	Specific surface area (m) ² /g)	Water absorption (%)
						Example 1	1350	60～80	760～900	6.0	64
Example 2	1280	45～60	650～790	6.5	55
						Example 3	1330	50～60	660～820	6.1	60
Example 4	1380	70～80	780～950	3.7	50
						Example 5	1250	45～55	350～520	9.8	65
Example 6	1330	50～60	660～820	6.1	60
						Comparative example 1	1350	60～80	760～900	6.0	64
Comparative example 2	1280	45～60	650～790	6.5	55
						Comparative example 3	1330	50～60	660～820	6.1	60
Comparative example 4	1380	70～80	780～950	3.7	50
						Comparative example 5	1250	45～55	350～520	9.8	65
Comparative example 6	1330	50～60	660～820	6.1	60

Table 4 catalyst active ingredient content for examples and comparative examples

The above catalyst was evaluated for performance in a fixed bed reactor.

TABLE 5 reaction mass composition

Hydrogenation process	Acetylene (acetylene)	Ethylene	Methane	Hydrogen gas	CO
						Ethane cracking	0.32	76	11.6	12.0	0.08

TABLE 6 evaluation results of catalysts

The reduction temperature peak of the catalyst carrying only Ni/Cu and the catalyst carrying only Pb-Ni/Cu as in example 1 were measured, the reduction peak of the catalyst carrying only Ni/Cu was about 350℃and the reduction temperature of the catalyst carrying only Pb-Ni/Cu was about 150 ℃.

Of course, the present invention is capable of other various embodiments and its several details are capable of modification and variation in light of the present invention by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing a high anti-coking alkyne-removal catalyst, which comprises the following steps:

2. The preparation method according to claim 1, wherein a majority of Pd is supported in solution and a minority of Pd is supported in a microemulsion manner such that the minority of Pd is mainly distributed in macropores of the support.

3. The preparation method according to claim 1, wherein the small pore diameter of the carrier is 40-75 nm, the large pore diameter is 200-650 nm, and the particle size of the microemulsion is controlled to be more than 75nm and less than 650nm when the microemulsion is loaded.

4. A method according to any one of claims 1 to 3, wherein the process of loading the microemulsion 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.

5. The method of claim 1, wherein the step of loading Pd in the microemulsion is after the step of loading Ni and Cu in the microemulsion.

6. The preparation method according to claim 1, wherein the carrier Al ₂ O ₃ The crystal form of (C) is alpha,θ or a mixed crystalline form thereof; the alumina in the carrier is more than 80 wt%.

7. The method according to claim 4, wherein the microemulsion has a weight ratio of 4.5 to 6.0 between the aqueous phase and the oil phase, a weight ratio of 0.10 to 0.35 between the surfactant and the oil phase, and a weight ratio of 1.0 to 1.2 between the surfactant and the cosurfactant.

8. The method according to claim 1, wherein the solution-supported Pd and the solution-supported Fe/Co are impregnated in supersaturated form.

9. The method according to claim 1, wherein the order of loading the Pd in solution and the Ni/Cu microemulsion is not limited, and the loading of the Pd in solution is before or after the loading of the Ni/Cu microemulsion.

10. The method according to claim 1, wherein the order of loading of the Fe and Co in solution is not limited, and the loading of the Fe and Co in solution is before or after the loading of the Pd.

11. The preparation method according to claim 1, characterized in that it comprises in particular the following steps:

(4) Dissolving Pd precursor salt in water, adding an oil phase, a surfactant and a cosurfactant, fully stirring to form microemulsion, controlling the particle size of the microemulsion to be more than 75nm and less than 650nm, adding a semi-finished catalyst C into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying at 80-120 ℃ for 1-6 hours, and roasting at 400-600 ℃ for 2-8 hours to obtain the catalyst.