CN117447292A

CN117447292A - Selective hydrogenation method for carbon two fractions

Info

Publication number: CN117447292A
Application number: CN202210850759.3A
Authority: CN
Inventors: 谭都平; 李保江; 张生芳; 李蓬勃; 康龙; 彭远嘱; 胥昌平; 张峰; 车春霞; 韩伟
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2022-07-19
Filing date: 2022-07-19
Publication date: 2024-01-26

Abstract

The invention provides a selective hydrogenation method of carbon two fractions, which comprises the steps of feeding the carbon two fractions into a reactor for gas phase hydrogenation to remove acetylene, wherein the inlet temperature of the reactor is 40-120 ℃, the pressure of the reactor is 1.5-3.0 MPa, and the gas volume space velocity is 1000-6000 h ^‑1 The hydrogen needed for the reaction is derived from crude hydrogen; the catalyst used for the gas phase hydrogenation acetylene removal reaction comprises a carrier and an active component, wherein the carrier comprises Al ₂ O ₃ The carrier has bimodal pore diameter distribution, the pore diameters are respectively 20-50 nm and 90-500 nm, and the active component at least comprises Pd, ni, cu, pt,The catalyst comprises 0.065-0.08% of Pd, 1-5% of Ni,2.1-5% of Cu,0.1-0.5% of Ce and 0.001-0.01% of Pt, calculated by 100% of the mass of the catalyst, wherein the loading of Ni and Cu adopts a microemulsion mode, the grain diameter of the microemulsion is 50-500 nm, and the loading of Pd, pt and Ce adopts a solution mode. The hydrogenation method has the characteristics of good selectivity in the hydrogenation process and long operation period.

Description

Selective hydrogenation method for carbon two fractions

Technical Field

The invention relates to the field of hydrogenation, in particular to a selective hydrogenation method of carbon two fractions.

Background

Ethylene is one of the most important base materials in the petrochemical industry, and as a monomer ethylene for synthesizing various polymers, most of ethylene is produced by steam cracking of petroleum hydrocarbons (e.g., ethane, propane, butane, naphtha, light diesel, etc.). C based on ethylene obtained by this process ₂ The fraction contains 0.5 to 2.3 percent (mole fraction) of acetylene. The presence of more acetylene in ethylene complicates the polymerization process of ethylene and deteriorates the polymer properties. And reduces the activity of the polymerization catalyst and increases the consumption of the catalyst. It is necessary to reduce the acetylene content of ethylene to a certain value or less in order to be used as a monomer for synthesizing a polymer.

At present, a selective hydrogenation method is generally adopted in industry to remove acetylene in ethylene, and the adopted catalyst is mainly a noble metal catalyst with Pd, pt, au and the like as active components. In order to ensure that ethylene generated by acetylene hydrogenation and original ethylene in raw materials are not continuously hydrogenated to generate ethane, so that ethylene loss is caused, the higher hydrogenation selectivity of the catalyst is ensured, and the economic benefit of the device can be improved.

Carbon di-hydrogenation is therefore an extremely important process in the petrochemical industry, which directly affects the stability of operation of the overall ethylene plant.

The hydrogenation process of the second carbon is mainly divided into two processes according to hydrogenation materials and conditions, namely, hydrogenation before the second carbon and hydrogenation after the second carbon. Since the location of the reactor determines the composition of the reaction materials, for example, front hydrogenation and back hydrogenation refer to the position of the acetylene hydrogenation reactor relative to the demethanizer, the hydrogenation reactor is positioned before the demethanizer and the hydrogenation reactor is positioned after the demethanizer.

The second-carbon post hydrogenation means that the hydrogenation raw material is a second-carbon fraction, hydrogen is added after metering, and is generally methane hydrogen and the like, wherein the content of the hydrogen is more than 88 percent, and reformed hydrogen is also adopted, and the content of the hydrogen can reach more than 99 percent.

The acetylene content at the inlet of the reactor determines the number of sections of the hydrogenation reactor adopted, and the acetylene content is generally lower than 0.8 percent, so that a single-section hydrogenation process can be adopted; acetylene content is higher than 0.8% and lower than 1.4%, and 2-stage hydrogenation process is generally adopted; above 1.4%, a three-stage hydrogenation process is generally required.

In the second-carbon hydrogenation reaction, the hydrodimerization of acetylene can occur to generate a series of oligomers with different molecular weights, and the oligomers can be attached to the surface of a catalyst or enter the pore canal for a long time due to the fact that the oligomers cannot flow along with gas-phase materials or have low moving speed, so that the catalyst pores are blocked. The oligomers themselves have a large amount of unsaturated bonds and can be further polymerized to finally form cokes, so that the activity selectivity of the catalyst is greatly reduced.

The amount of the hydrodimerization product is closely related to the hydrogenation condition, and the hydrodimerization reaction of acetylene is very intense due to the shortage of hydrogen at the time of low hydrogen/alkyne; the catalyst coking rate can be quite rapid.

For the traditional three-stage hydrogenation process, the total conversion rate of acetylene in the first-stage reactor is 50-90%, the total conversion rate of acetylene in the second-stage reactor is 40-20%, the total conversion rate of hydrogen/acetylene is 1.4-2.0, the residual acetylene is completely converted in the third-stage reactor, the total conversion rate of acetylene in the third-stage reactor is 2.5-4.0, and the acetylene content at the outlet of the third-stage reactor is generally below 1 ppm.

In the reaction process, as the alkyne removal load of the first-stage reactor is large, the green oil generated by the first-stage reactor is the largest, the hydrodimerization reaction at the inlet of the first-stage reactor is the most intense, and part of green oil is polymerized at the inlet of the first-stage reactor, so that the activity of the catalyst is rapidly reduced. The other part is the outlet of the one-stage reactor, because as the hydrogenation proceeds, the hydrogen/alkyne ratio becomes lower and the rate of the hydrodimerization increases again, and the increase in temperature increases the polymerization of the green oil.

The partial carbon two-post hydrogenation device adopts a two-stage hydrogenation process, green oil generated by the first-stage reactor partially enters the second-stage reactor and is accumulated at the inlet of the second-stage reactor to form coking, so that the hydrogenation effect of the second-stage reactor is rapidly deteriorated, and the acetylene content at the outlet of the reactor is rapidly increased to be more than 1ppm, and therefore, for the two-stage hydrogenation process, the catalyst performance, especially the anti-coking performance of the catalyst, is required to be better in principle.

And part of ethylene devices, such as diesel oil, heavy naphtha, hydrogenated tail oil and the like, are used as raw materials, and because the acetylene content in a pyrolysis product is low, the carbon two-fraction adopts single-stage hydrogenation, so that the requirement on the stability of the catalyst is higher, and the acetylene content at the outlet of the reactor is increased due to the influence of green oil after the catalyst is operated for 3 months, so that the requirement of less than or equal to 1ppm cannot be met, the hydrogen amount needs to be increased, and the ethylene loss is large.

In some three-stage hydrogenation devices, in order to adjust the hydrogenation load of each reactor, the amount of hydrogen to be added is sometimes reduced artificially, so that the hydrogen/alkyne ratio at the inlet of a certain reactor is even lower than 1, the coking of the catalyst is greatly accelerated, and the operation period of the catalyst is obviously shortened although the load of each reactor is adjusted.

There are also some units in which the hydrogen separated in the methane column is not subjected to methanation and further separation, called crude hydrogen, i.e., is used as hydrogen. These crude hydrogen contains hydrogen, methane, and also CO. The content of CO in the crude hydrogen can reach 1% (V) at most. Because CO and acetylene and the like form competitive adsorption on the surface of the catalyst, the hydrogenation reaction rate of acetylene is reduced, but the selectivity of the reaction is also improved. In the selective hydrogenation reaction, CO also undergoes a hydroformylation reaction to produce an oxygen-containing compound such as an aldehyde, and unlike hydrocarbons, these oxygen-containing compounds are more easily adsorbed on an alumina carrier and accumulate to form coking.

Once the coking amount reaches more than 10% of the mass of the carbon two hydrogenation catalyst, the performance is obviously reduced, and the generation of green oil seriously affects the performance of the carbon two post hydrogenation catalyst, but the hydrodimerization is unavoidable, so that how to reduce the generation of the green oil and delay the coking becomes one of the perpetual subjects in the design of the catalyst.

In the conventional two-carbon post-hydrogenation reaction, the hydrogen amount is generally prepared by multiplying the acetylene content by a fixed hydrogen/alkyne ratio, and the maximum first stage is generally not more than 1.4, if the CO content is higher, the selectivity of the reaction is improved, and the hydrogen/alkyne ratio can be correspondingly improved.

Because the content of hydrogen in the post-hydrogenation material is low, the hydrogenation dimerization reaction of acetylene is easy to occur, and a carbon four-fraction is generated, and the carbon four-fraction is further polymerized to generate an oligomer with wider molecular weight, which is commonly called as green oil. Green oil adsorbs on the catalyst surface and further forms coke, blocking catalyst pore channels, preventing the reactant from diffusing to the surface of the active center of the catalyst, thereby causing the activity of the catalyst to be reduced.

The mechanism of acetylene hydrogenation is: first, one acetylene molecule is combined with 1 hydrogen atom to form vinyl group, and the next reaction has 2 competing paths: 1) Vinyl groups are combined with hydrogen atoms to form ethylene; 2) 2 vinyl groups are coupled to form butadiene. If the hydrogen is small, the reaction of the path 2 is easy to occur to form butadiene, and a series of polymerization reactions can be carried out on the butadiene to form green oil and then coke is formed.

If more hydrogen is used, more reaction can be carried out according to the path 1), but the reaction of the path 2) cannot be completely stopped, if more hydrogen is used, the ethylene generated by the path 1) is promoted to undergo hydrogenation reaction again to generate ethane, and the loss of ethylene is caused, so that the hydrogen amount must be in a reasonable range so as to reduce the generation of green oil and not cause excessive loss of ethylene.

US5856262 reports a process for preparing a low acidity palladium catalyst using potassium hydroxide (or hydroxide of barium, strontium, rubidium, etc.) modified silica as support, at a space velocity of 3000h ^-1 The inlet temperature is 35 ℃, the mole fraction of the inlet acetylene is 0.71 percent, and the mole fraction of the outlet acetylene is less than 1 multiplied by 10 under the condition of the mole ratio of the hydrogen to the acetylene of 1.43 ^-7 The ethylene selectivity reaches 56%.

CN200810114744.0 discloses a catalyst for selective hydrogenation of unsaturated hydrocarbon, a preparation method and an application method. The catalyst takes alumina as a carrier and palladium as an active component, and the rare earth, alkaline earth metal and fluorine are added to improve the impurity resistance and coking resistance of the catalyst, but the selectivity of the catalyst is not ideal.

CN200810119385.8 discloses a non-noble metal supported selective hydrogenation catalyst, its preparation method and application, comprising a carrier, and a main active component and a co-active component supported on the carrier, wherein the main active component is Ni, the co-active component is at least one selected from Mo, la, ag, bi, cu, nd, cs, ce, zn and Zr, the main active component and the co-active component are both in amorphous form, the average particle size is less than 10nm, and the carrier is a porous material without oxidizing property; and the catalyst is prepared by a micro-emulsification method.

The catalyst prepared by the method adopts a catalyst with single pore diameter distribution, and is affected by internal diffusion, so that the selectivity of the catalyst is poor. The carrier with double-peak pore distribution ensures high activity of the catalyst, and the existence of macropores can reduce the influence of internal diffusion and improve the selectivity of the catalyst.

ZL971187339 discloses a hydrogenation catalyst, wherein the carrier is a honeycomb carrier, and is a large-aperture carrier, so that the selectivity of the catalyst is effectively improved.

CN1129606a discloses a hydrocarbon conversion catalyst and a preparation method, wherein the carrier catalyst comprises alumina, nickel oxide, iron oxide and the like, and the catalyst comprises two kinds of holes, one of which is used for improving the catalytic reaction surface, and the other is beneficial to diffusion.

CN101433842a discloses a hydrogenation catalyst, wherein the catalyst has a bimodal pore distribution, the most probable radius of the small pore portion is 2-50 nm, the most probable radius of the large pore portion is 100-400 nm, and the catalyst has good hydrogenation activity and good selectivity and large ethylene increment at the same time of the bimodal pore distribution.

201310114070.5A process for selecting two carbon fractions, in which a catalyst is used, the active components Pd and Ag are loaded by aqueous solution impregnation and Ni is loaded by W/O microemulsion impregnation. After the method is adopted, pd/Ag and Ni are positioned in pore channels with different pore diameters, green oil generated by the reaction is subjected to saturated hydrogenation in macropores, and the coking amount of the catalyst is reduced.

The catalyst needs to be reduced before it is put into operation. The noble metal catalyst has lower reduction temperature, but the reduction temperature of Ni is about 500 ℃, pd atoms in a reduced state are easy to gather at the temperature, so that the activity of the catalyst is reduced by more than 30%, and the activity loss is compensated by greatly increasing the equivalent amount of active components, but the selectivity is reduced.

201910988247.1A selective hydrogenation process for preparing catalyst features that the carrier of catalyst is in bimodal pore distribution, and in the course of preparing said catalyst, 2 approaches are used to load active components, and the solution method is used to load part of Pd in small pores as active component for main reaction. In addition, the W/O microemulsion with the particle size larger than that of the carrier pores is prepared, the microemulsion contains metal salts of nickel and copper, and the components are distributed in the carrier macropores to form Ni-Cu active centers.

The catalyst prepared by the method ensures that the selective hydrogenation reaction is mainly carried out on small holes, green oil generated by the reaction enters large holes and is subjected to saturated hydrogenation on Ni-Cu active centers, and the coking amount of the catalyst is reduced.

The reduction temperature of Ni-Cu is about 350 ℃, pd atoms in a reduced state are easy to aggregate at the temperature, the activity of the catalyst is greatly reduced, and in order to reduce the reduction temperature of the Ni-Cu active center, a small amount of palladium is loaded on the outer surface of the Ni-Cu active center by an emulsion method to form the Ni-Cu-Pd active center, so that the reduction temperature can be reduced to 150 ℃. The palladium is loaded for 2 times, so that the content of the palladium in the catalyst is higher than that of the common catalyst by more than 50 percent at most, the cost of the catalyst is greatly increased, and the preparation process of the catalyst is more complicated.

If the hydrogenation raw material contains CO, the hydrogenation process has hydroformylation reaction to generate aldehyde, ketone, acid and the like, and the fractions are more easily adsorbed on an alumina carrier, so that the green oil coking process is accelerated. However, in the above-disclosed catalyst, the main active component is Pd, the by-product is hydrogenated mainly by Ni, and these components have no carbonyl hydrogenation effect, that is, the coking rate of the carbon di-hydrogenation catalyst with CO can not be reduced very effectively.

Disclosure of Invention

The invention mainly aims to provide a selective hydrogenation method for a carbon two-fraction, which aims to overcome the defects that the preparation process of a catalyst for the selective hydrogenation of the carbon two-fraction is complex, the catalyst is easy to accumulate carbon in the selective hydrogenation process of the carbon two-fraction in the prior art, and the like.

In order to achieve the aim, the invention provides a selective hydrogenation method for a carbon two-fraction, wherein the carbon two-fraction enters a reactor to carry out gas-phase hydrogenation to remove acetylene, the inlet temperature of the reactor is 40-120 ℃, the pressure of the reactor is 1.5-3.0 MPa, and the gas volume space velocity is 1000-6000 h ^-1 The hydrogen needed for the reaction is derived from crude hydrogen; the catalyst used for the gas phase hydrogenation acetylene removal reaction comprises a carrier and an active component, wherein the carrier comprises Al ₂ O ₃ The carrier has bimodal pore size distribution, the pore size is respectively 20-50 nm and 90-500 nm, the active component comprises Pd, ni, cu, pt, ce, and the catalyst contains 0.065-0.08% Pd, 1-5% Ni,2-5% Cu,0.1-0.5% Ce and 0.001-0.01% Pt based on 100% of the mass of the catalyst, wherein the loading of Ni and Cu adopts microemulsionThe particle size of the microemulsion is 50-500 nm, and Pd, pt and Ce are loaded in a solution mode.

The invention relates to a selective hydrogenation method of a carbon two-fraction, wherein the carbon two-fraction is a carbon two-fraction at the top of a front deethanizer, and the reactor is a fixed bed reactor.

The invention relates to a selective hydrogenation method of a carbon two fraction, wherein the volume content of ethylene in the carbon two fraction is 60-90%, the volume content of acetylene is 0.1-1.0%, and the volume content of carbon three is 0.01-5%.

The invention relates to a selective hydrogenation method of a carbon two-fraction, wherein the volume content of CO in crude hydrogen is 0.1-1%, and the volume content of hydrogen is 20-70%.

The invention relates to a selective hydrogenation method of a carbon two-fraction, wherein the reactor is a single-stage reactor, and the molar ratio of hydrogen to alkyne at the inlet of the reactor is 1.3-2.0; or the reactor is a two-stage reactor, the mole ratio of hydrogen to alkyne at the inlet of the first-stage reactor is 1.1-1.3, and the mole ratio of hydrogen to alkyne at the inlet of the second-stage reactor is 1.3-2.0.

The selective hydrogenation method of the carbon two fraction, disclosed by the invention, is characterized in that Pt and Ce are simultaneously loaded, and Pd is loaded and roasted.

The invention relates to a selective hydrogenation method of a carbon two-fraction, wherein the solution mode loading refers to preparing a precursor of an active component into a solution, and then loading the precursor of the active component on a carrier in a carrier impregnation mode; the microemulsion loading means that the precursor of the active component is prepared into microemulsion, and then the precursor of the active component is loaded on the carrier by a carrier impregnation method.

The invention relates to a selective hydrogenation method of a carbon two-fraction, wherein the mode of preparing microemulsion is as follows: dissolving precursors of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; wherein the weight ratio of the surfactant to the cosurfactant is 1-1.2, the weight ratio of the water phase to the oil phase is 2.0-3.0, and the weight ratio of the surfactant to the oil phase is 0.15-0.6.

The invention relates to a selective hydrogenation method of a carbon two-fraction, wherein the preparation method of the catalyst comprises the following steps:

step 1, dissolving a precursor of Ni and a precursor of Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; the weight ratio of the surfactant to the cosurfactant is 1-1.2, the weight ratio of the water phase to the oil phase is 2.0-3.0, and the weight ratio of the surfactant to the oil phase is 0.15-0.6; adding the carrier into the prepared microemulsion for soaking, drying and roasting to obtain a semi-finished catalyst A;

Step 2, dissolving a Pd precursor in water, adjusting the pH to 1.5-2.5, adding a semi-finished catalyst A, dipping, drying and roasting to obtain a semi-finished catalyst B;

and 3, dissolving a Pt precursor and a Ce precursor in water, adjusting the pH to 1.0-3.0, adding a semi-finished catalyst B, dipping, drying and roasting to obtain the catalyst.

step 1, dissolving a Pd precursor in water, adjusting the pH to 1.5-2.5, adding a carrier, dipping, drying and roasting to obtain a semi-finished catalyst A;

step 2, dissolving a Pt precursor and a Ce precursor in water, adjusting the pH to 1.0-3.0, adding a semi-finished catalyst A, dipping, drying and roasting to obtain a semi-finished catalyst B;

step 3, dissolving a precursor of Ni and a precursor of Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; the weight ratio of the surfactant to the cosurfactant is 1-1.2, the weight ratio of the water phase to the oil phase is 2.0-3.0, and the weight ratio of the surfactant to the oil phase is 0.15-0.6; and (3) adding the semi-finished catalyst B into the prepared microemulsion for soaking, drying and roasting to obtain the catalyst.

The invention has the beneficial effects that:

according to the hydrogenation method, the Ni-Cu active center can carry out saturated hydrogenation on byproducts generated in hydrogenation, so that the coking rate of the catalyst is reduced, the hydrogenation process can be carried out in a high-selectivity state for a long time, and the operation period of the reactor is long;

according to the invention, by increasing the content of Cu, part of Cu is positioned on the outer surface of the Ni-Cu alloy, so that carbonyl compounds generated in the raw material reaction process can be hydrogenated, and the coking rate of the catalyst is reduced;

the noble metal palladium loading amount is low, the Ce and Pt are loaded by a solution method, the problem of palladium aggregation in the activation process is solved, the obtained catalyst has high catalyst activity and selectivity, and meanwhile, the preparation method of the catalyst is simple and easy to industrialize.

Detailed Description

The following describes the present invention in detail, and the present examples are implemented on the premise of the technical solution of the present invention, and detailed embodiments and processes are given, but the scope of protection of the present invention is not limited to the following examples, in which the experimental methods of specific conditions are not noted, and generally according to conventional conditions.

The invention provides a selective hydrogenation method of carbon two fractions, which comprises the steps of feeding the carbon two fractions into a reactor for gas phase hydrogenation to remove acetylene, wherein the inlet temperature of the reactor is 40-120 ℃, the pressure of the reactor is 1.5-3.0 MPa, and the gas volume space velocity is 1000-6000 h ^-1 The hydrogen needed for the reaction is derived from crude hydrogen; the catalyst used for the gas phase hydrogenation acetylene removal reaction comprises a carrier and an active component, wherein the carrier comprises Al ₂ O ₃ The carrier has bimodal pore size distribution, the pore size is respectively 20-50 nm and 90-500 nm, the active component comprises Pd, ni, cu, pt, ce, the catalyst contains 0.065-0.08% of Pd, 1-5% of Ni,2-5% of Cu,0.1-0.5% of Ce and 0.001-0.01% of Pt by taking the mass of the catalyst as 100%, wherein the loading of Ni and Cu adopts a microemulsion mode, the particle size of the microemulsion is 50-500 nm, and the loading of Pd, pt and Ce adopts a solution mode.

The carbon two fraction of the present invention mainly contains ethylene and contains a small amount of acetylene. In one embodiment, the carbon two fraction of the present invention is the carbon two fraction at the top of the front deethanizer; in another embodiment, the carbon two fraction of the invention has an ethylene volume content of 60-90%, an acetylene volume content of 0.1-1.0% and a carbon three volume content of 0.5-5%.

The active components Ni-Cu of the catalyst are loaded in a micro-emulsion manner and are mainly distributed in a macroporous pore canal of a carrier, the active components Pd, pt and Ce are loaded in a solution manner and are mainly distributed in a small pore canal of the carrier, so that the selective hydrogenation reaction of acetylene is mainly carried out under the catalysis of Pd in the small pore canal, and a polymer generated by the reaction enters the macroporous pore canal and is subjected to saturated hydrogenation reaction in the active center of Ni-Cu, thereby reducing the coking amount of the catalyst. The reduction temperature of Ni-Cu is about 350 ℃, pd atoms in a reduced state are easy to aggregate at the temperature, and the Pd atom aggregation phenomenon can be greatly relieved through the loading of Pt and Ce.

In detail, when Pt and Ce are impregnated as metal salts, pt exists, for example, in an anionic form, more for example, in the form of chloroplatinic acid, ce exists, for example, in a cationic form, for example, formation of cerium chloride or cerium nitrate, which forms a cerium ion pair of chloroplatinic acid, and a small amount of platinum must be present with Ce ⁴⁺ Together. In the roasting activation process, cerium is firstly converted into cerium oxide, the cerium oxide is covered on the surface of aluminum oxide, platinum forms platinum oxide, and the binding force of the cerium oxide and the platinum oxide is far higher than that of the platinum oxide and the aluminum oxide, so that firm combination can be formed. The combination basically exists in the form of single atoms of platinum, and plays a role similar to a fence around palladium atoms, so that the migration of palladium atoms is prevented, and the aggregation phenomenon of Pd atoms is further relieved.

In addition, the invention improves the content of Cu to ensure that part of Cu is positioned on the outer surface of the Ni-Cu alloy, so that carbonyl generated in the raw material reaction process can be hydrogenated, and the coking rate of the catalyst is reduced.

The catalyst of the present invention comprises a carrier and an active component, the active component being supported on the carrier. In one embodiment, the support of the present invention is Al ₂ O ₃ Or mainly Al ₂ O ₃ . In another embodiment, the catalyst support of the present invention further comprises The mass content of titanium oxide, for example, titanium oxide is 10%.

The catalyst of the invention at least comprises Pd, ni, cu, pt, ce, wherein Ni and Cu are loaded in a microemulsion way, the particle size of the microemulsion is 50-500 nm, pd, pt and Ce are loaded in a solution way, so that the Pd, pt and Ce are only distributed in small pore-diameter pore channels of 20-50 nm, and the Ni and Cu are mainly distributed in large pore-diameter pore channels of 90-500 nm.

The solution loading means that the precursor of the active component is prepared into a solution, and then the precursor of the active component is loaded on the carrier in a carrier impregnating way; microemulsion loading refers to the preparation of a precursor of an active component into a microemulsion and then loading the precursor of the active component on a carrier by a method of impregnating the carrier.

The Pd, pt and Ce are loaded in a solution mode, namely, a Pd precursor, a Pt precursor and a Ce precursor are prepared into a solution, and then a carrier is added for impregnation. The Pt and Ce are loaded simultaneously, and Pd is required to be loaded and roasted.

The Ni and Cu are loaded in a microemulsion mode, namely, ni precursors and Cu precursors are prepared into microemulsion, and then a carrier is added for loading. The invention is not particularly limited in the loading sequence of Ni and Cu, for example, the loading can be carried at the same time, and the Cu can be loaded on the outer surface of the Ni-Cu alloy by increasing the loading of Cu, so that the carbonyl generated in the raw material reaction process can be subjected to catalytic hydrogenation, and the coking rate of the catalyst is reduced.

The present invention is not particularly limited to the manner of preparing the microemulsion, and for example, the manner of preparing the microemulsion is: dissolving precursors of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; wherein the weight ratio of the surfactant to the cosurfactant is 1-1.2, the weight ratio of the water phase to the oil phase is 2.0-3.0, and the weight ratio of the surfactant to the oil phase is 0.15-0.6.

The present invention is not particularly limited to the order of loading Ni and Cu and Pd, and for example, pd may be loaded in the solution after Ni and Cu are loaded in the microemulsion, or Ni and Cu may be loaded in the microemulsion after Pd is loaded in the solution.

In one embodiment, the method of preparing the catalyst of the present invention comprises:

In another embodiment, the method of preparing the catalyst of the present invention comprises:

In yet another embodiment, the method of preparing the catalyst of the present invention comprises:

Step 2, dissolving a precursor of Ni and a precursor of Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; the weight ratio of the surfactant to the cosurfactant is 1-1.2, the weight ratio of the water phase to the oil phase is 2.0-3.0, and the weight ratio of the surfactant to the oil phase is 0.15-0.6; adding the semi-finished catalyst A into the prepared microemulsion for soaking, drying and roasting to obtain a semi-finished catalyst B;

Wherein, the time of the soaking step is 0.5-4 hours, the roasting temperature is 400-600 ℃, but the invention is not limited to the above.

The present invention is not particularly limited in the type of active ingredient precursor, for example, soluble salts of the active ingredient, more for example, nitrate, chloride, etc. of the active ingredient.

The selective hydrogenation method of the carbon dioxide fraction can use crude hydrogen as a hydrogen source to carry out selective hydrogenation of the carbon dioxide fraction, the crude hydrogen is added after metering, the volume content of CO in the crude hydrogen is 0.1-1%, and the volume content of hydrogen is 20-70%. In one embodiment, the reactor in which the selective hydrogenation of the present invention is carried out is a fixed bed reactor, for example an adiabatic or isothermal fixed bed reactor. In another embodiment, the reactor of the present invention is a single stage reactor having an inlet hydrogen/alkyne molar ratio (i.e., the molar ratio of hydrogen to alkyne in the hydrogenation feedstock) of from 1.3 to 2.0. In yet another embodiment, the reactor of the present invention is a two-stage reactor, the first stage reactor inlet hydrogen/alkyne molar ratio is from 1.1 to 1.5 and the second stage reactor inlet hydrogen/alkyne molar ratio is from 1.3 to 2.0.

In one embodiment, the reaction conditions for the selective hydrogenation of the carbon two fractions of the present invention are: the inlet temperature of the reactor is 40-120 ℃, the reaction pressure is 1.5-3.0 MPa, and the gas volume space velocity is 1000-6000 h ^-1 .

The method for selectively hydrogenating the carbon two fraction can lead the acetylene content in the product at the outlet of the reactor to be lower than 1ppm.

In addition, the coking speed of the catalyst is very slow in the use process, and the oxygen-containing compound generated in the reaction has no obvious influence on the performance of the catalyst; the performance of the catalyst is basically unchanged after 5 times of regeneration, which indicates that the aggregation state of main active components of the catalyst is not influenced by a plurality of high-temperature reduction processes, and the service life of the catalyst is longer.

The technical scheme of the invention will be further described in detail through specific examples.

The device comprises: a dynamic light scattering particle size analyzer, on which the microemulsion particle size distribution of the Ni/Cu alloy is analyzed; the pore volume, specific surface area and pore size distribution of the support were analyzed on a fully automated mercury porosimeter, model 9510 of the american microphone company. The Pd, ni, cu, ce, pt content of the catalyst was measured on an a240FS atomic absorption spectrometer.

Raw materials: nickel nitrate, copper nitrate, palladium chloride, chloroplatinic acid, analytically pure, shanghai national pharmaceutical Congress; alumina, shandong aluminum products group Co.

Example 1

Catalyst preparation

And (3) a carrier: the commercial bimodal pore distribution spherical carrier was weighed to have an alumina content of 90wt%, a titania content of 10wt% and a spherical diameter of 4mm. After 4 hours of calcination at 1150 ℃, the pore size distribution ranges are 35-50 nm and 320-500 nm, the water absorption is 50%, and the specific surface area is 20.25m ² 100g of the carrier was weighed.

(1) Weighing 0.125g of palladium chloride salt, dissolving in 140mL of deionized water, adjusting the pH to 1.5, adding the carrier into Pd salt solution, soaking and adsorbing for 50min, drying at 110 ℃, and roasting at 500 ℃ for 5h to obtain a required semi-finished catalyst A;

(2) 15.57g of anhydrous nickel nitrate, 23.25g of copper nitrate hexahydrate, dissolved in 75mL of deionized water, 25g of normal hexane, 3.75g of CATB, 3.13g of n-amyl alcohol and fully stirred to form microemulsion. And (3) adding the semi-finished catalyst A into the prepared microemulsion, soaking for 80min, filtering out residual liquid, and washing with deionized water until the residual liquid is neutral. Drying at 80 ℃, and roasting at 500 ℃ for 4 hours to obtain a semi-finished catalyst B;

(3) Weighing 0.176 g of cerium chloride, dissolving 0.0011g of chloroplatinic acid in 50mL of deionized water, adjusting the pH to 1.0, immersing the obtained semi-finished catalyst B into the prepared solution, drying at 120 ℃ for 5 hours after the solution is completely absorbed, and roasting at 500 ℃ for 4 hours to obtain the catalyst.

The particle size of the microemulsion prepared in the step (2) is 496.66nm by a dynamic light scattering method.

The element content was measured by atomic absorption spectrometry to obtain a catalyst of example 1 having a Pd content of 0.075%, a Ni content of 5%, a Cu content of 5%, a Ce content of 0.1% and a Pt content of 0.005%.

Comparative example 1

The same carrier as in example 1 was used, and the preparation method was the same, except that Cu was not supported

(1) Weighing 0.125g of palladium chloride salt, dissolving in 140mL of deionized water, adjusting the pH to 1.5, adding the carrier into Pd salt solution, soaking and adsorbing for 50min, drying at 110 ℃, and roasting at 500 ℃ for 5h to obtain a required semi-finished catalyst A1;

(2) 15.57g of anhydrous nickel nitrate is weighed and dissolved in 75mL of deionized water, 25g of normal hexane is added, 3.75g of CATB is added, 3.13g of normal amyl alcohol is added, and the mixture is fully stirred to form microemulsion. And adding the semi-finished catalyst A1 into the prepared microemulsion, soaking for 80min, filtering out residual liquid, and washing with deionized water until the residual liquid is neutral. Drying at 80 ℃, and roasting at 500 ℃ for 4 hours to obtain a semi-finished catalyst B1;

(3) Weighing 0.176 g of cerium chloride, dissolving 0.0011g of chloroplatinic acid in 50mL of deionized water, adjusting the pH to 1.0, immersing the obtained semi-finished catalyst B1 into the prepared solution, drying at 120 ℃ for 5 hours after the solution is fully absorbed, and roasting at 500 ℃ for 4 hours to obtain the catalyst.

The element content was measured by atomic absorption spectrometry to obtain a catalyst of example 1 having a Pd content of 0.075%, a Ni content of 5%, a Ce content of 0.1% and a Pt content of 0.005%.

The implementation effect is as follows:

reduction of the catalyst: reducing gas: hydrogen, space velocity of reduction: 100h ^-1 The temperature is 350 ℃ and kept for 4 hours.

Working condition 1:

and (2) raw materials of carbon: acetylene 0.3% (v/v), ethylene 60% (v/v), carbon three 0.5% (v/v), and the remainder ethane.

Crude hydrogen: 70% of hydrogen, 29% of methane and 1% of CO.

The CO content of the hydrogenated material was 18ppm.

The process conditions are as follows: a single-stage reactor, the space velocity of materials is 6000/h, the operating pressure is 1.5MPa, the inlet temperature of the reactor is 120 ℃, the molar ratio of hydrogen to alkyne is 1.3, and the catalyst loading is 100mL.

TABLE 1 reaction results

In example 1, in working condition 1, the acetylene content at the outlet of the reactor was always lower than 1ppm from the beginning of the reaction to 500 hours, and the acetylene content at the outlet of the reactor was still lower than 1ppm after 5 times of catalyst regeneration.

Comparative example 1 in working condition 1, the same effect as in example 1 was obtained at 24 hours, and the acetylene content at the reactor outlet of comparative example 1 was remarkably increased after 500 hours. The reason is that the catalyst is not loaded with Cu, ni is not fully reduced at 350 ℃, and the saturated hydrogenation effect on byproducts is not achieved.

Working condition 2:

and (2) raw materials of carbon: acetylene 0.1% (v/v), ethylene 80% (v/v), and C ₃ 0.01% (v/v), the remainder being ethane.

Crude hydrogen: hydrogen volume content 50%, methane volume content 29%, CO volume content 0.5%.

The CO content of the hydrogenated material was 18ppm.

The process conditions are as follows: a single-stage reactor, a material space velocity of 1000/h, an operating pressure of 2.0MPa, a reactor inlet temperature of 40 ℃, a hydrogen/alkyne molar ratio of 1.8 and a catalyst loading of 100mL.

TABLE 2 reaction results

In example 2, the acetylene content at the reactor outlet was always below 1ppm from the start of the reaction to 1000 hours, and was still below 1ppm after 5 regenerations of the catalyst.

In the working condition of comparative example 2, the effect is the same as that of example 1 at 24 hours, and the acetylene content at the outlet of the reactor of comparative example 1 is obviously increased after 1000 hours. After 1000 hours, the coking amount of the catalyst exceeds 10 percent, and the catalyst performance has been obviously reduced. The reason is that the catalyst is not loaded with Cu, ni is not fully reduced at 350 ℃, and the saturated hydrogenation effect on byproducts is not achieved.

Example 2

And (3) preparing a catalyst:

and (3) a carrier: the commercial bimodal pore distribution spherical alumina carrier was weighed to a diameter of 4mm. After being roasted for 4 hours at 1115 ℃, the pore size distribution ranges are respectively 35-46 nm and 260-440 nm, the water absorption is 55%, and the specific surface area is 25m ² 100g of the carrier was weighed.

(1) 3.11g of anhydrous nickel nitrate, 4.24g of copper chloride are weighed and dissolved in 60mL of deionized water, 27.50g of cyclohexane is added, 15.50g of Triton X-100 is added, 15.30g of n-amyl alcohol is added, and the mixture is fully stirred to form microemulsion. Adding the carrier into the prepared microemulsion, soaking for 4 hours, filtering residual liquid, drying at 80 ℃, and roasting at 400 ℃ for 4 hours to obtain a required semi-finished catalyst C;

(2) Weighing 0.14g of palladium nitrate, dissolving in 120mL of deionized water, adjusting the pH to 1.9, adding the semi-finished catalyst C into a Pd salt solution, soaking and adsorbing for 1 hour, drying at 120 ℃, and roasting at 600 ℃ for 4 hours to obtain a finished catalyst D;

(3) 1.55g of cerium nitrate and 0.0021g of chloroplatinic acid are weighed and dissolved in 54mL of deionized water, the pH value is adjusted to 2.0, then the semi-finished catalyst D is immersed into the prepared solution, after the solution is fully absorbed, the solution is dried for 5 hours at 120 ℃, and baked for 5 hours at 600 ℃, thus obtaining the required catalyst.

The particle size of the microemulsion prepared in the step (1) is 66.41nm by a dynamic light scattering method (laser light scattering method).

The element content was measured by atomic absorption spectrometry to obtain a catalyst of example 2 having a Pd content of 0.065%, a Ni content of 1%, a Cu content of 2%, a Ce content of 0.5% and a Pt content of 0.001%.

Comparative example 2 (no Pt loading)

And (3) a carrier: the commercial bimodal pore distribution spherical alumina carrier was weighed to a diameter of 4mm. After being roasted for 4 hours at 1115 ℃, the pore size distribution ranges are 27-46 nm and 260-440 nm, the water absorption is 55%, and the specific surface area is 25m ² 100g of the carrier was weighed.

(1) 3.11g of anhydrous nickel nitrate, 4.24g of copper chloride are weighed and dissolved in 60mL of deionized water, 27.50g of cyclohexane is added, 15.50g of Triton X-100 is added, 15.30g of n-amyl alcohol is added, and the mixture is fully stirred to form microemulsion. Adding the carrier into the prepared microemulsion, soaking for 4 hours, filtering out residual liquid, drying at 80 ℃, and roasting at 400 ℃ for 4 hours to obtain a required semi-finished catalyst C1;

(3) Weighing 0.14g of palladium nitrate, dissolving in 120mL of deionized water, adjusting the pH to 1.9, adding the semi-finished catalyst C1 into a Pd salt solution, soaking and adsorbing for 1 hour, drying at 120 ℃, and roasting at 600 ℃ for 4 hours to obtain a finished catalyst D1;

(3) 1.55g of cerium nitrate is weighed and dissolved in 54mL of deionized water, the pH is adjusted to 2.0, then the semi-finished catalyst D1 is immersed into the prepared solution, after the solution is completely absorbed, the solution is dried for 5 hours at 120 ℃, and baked for 5 hours at 600 ℃, thus obtaining the required catalyst.

The atomic absorption spectrometry was used to determine the element content, and the catalyst of comparative example 2 was obtained with a Pd content of 0.065%, a Ni content of 1%, a Cu content of 2% and a Ce content of 0.5%.

Effect of the invention

Reduction of the catalyst: reducing gas: hydrogen gasSpace velocity of reduction: 100h ^-1 The temperature was 380℃and maintained for 4h.

And (2) raw materials of carbon: acetylene 0.6% (v/v), ethylene 80% (v/v), carbon three 5% (v/v),

crude hydrogen: hydrogen volume content 50%, methane volume content 49.5%, and CO volume content 0.5%.

(the remainder being ethane or the like)

The CO content of the hydrogenated material was 120ppm.

The process conditions are as follows: the space velocity of the material is 4000/h, the operating pressure is 2.0MPa, the inlet temperature of the reactor is 90 ℃, the molar ratio of hydrogen to alkyne is 2.0, and the catalyst loading amount is 100mL.

The reaction results are shown in Table 2.

TABLE 2 reaction results

As shown in Table 2, the reactor outlet acetylene content in comparative example 2 was higher than that in example 2 at 24 hours; by 500 hours, the reactor outlet acetylene content of comparative example 2 was unacceptable. The reason may be that the Pt was not supported in comparative example 2, the Pd active sites in comparative example 2 were already partially aggregated at 380 ℃ for reduction, and the catalyst activity was lowered. After 500 hours, although the reactor inlet acetylene content was much higher than in example 2, catalyst coking was not very severe and the reasons for off-specification of comparative example 2 outlet acetylene content could be mainly due to the high acetylene content in the feed.

After 5 regenerations, the catalyst of comparative example 2 was nearly unacceptable at 24 hours at the reactor outlet for the possible reason that the reduction at 400 ℃ for 5 times in the absence of Pt had made the aggregation of Pd active sites more severe, resulting in a decrease in catalyst activity selectivity.

Example 3

And (3) preparing a catalyst:

a commercial bimodal pore distribution spherical alumina support was 4mm in diameter. After roasting for 4 hours at 1100 ℃, the pore size distribution ranges are 25-40 nm and 100-280 nm, the water absorption rate is 52%, and the specific surface area is 30.16m ² 100g of the carrier was weighed.

(1) 6.63g of anhydrous nickel chloride, 8.85g of copper nitrate are weighed and dissolved in 75mL of deionized water, 33g of cyclohexane is added, 17.6g of Triton X-100 is added, 17.2g of n-amyl alcohol is added, and the mixture is fully stirred to form microemulsion. The carrier is added into the prepared microemulsion to be immersed for 30min, residual liquid is filtered, dried at 40 ℃ and baked at 600 ℃ for 6h. Obtaining a semi-finished catalyst E;

(2) Weighing 0.117g of palladium chloride, dissolving in 120mL of deionized water, adjusting the pH to 2.5, adding the semi-finished catalyst E into a Pd salt solution, soaking and adsorbing for 30min, drying at 100 ℃, and roasting at 550 ℃ for 6h to obtain a semi-finished catalyst F;

(3) Dissolving 0.93g cerium nitrate 0.93g and 0.0084g chloroplatinic acid in 50mL deionized water, adjusting pH to 3.0, soaking the semi-finished catalyst F in the prepared solution, drying at 120deg.C for 5 hours after the solution is fully absorbed, and roasting at 550deg.C for 5 hours to obtain the final catalyst

The particle size of the microemulsion prepared in the step (1) is 100.58nm as measured by a dynamic light scattering method,

the content of the element was measured by atomic absorption spectrometry to obtain a catalyst prepared in example 3, wherein the Pd content was 0.07%, the Ni content was 3%, the Cu content was 3%, the Ce content was 0.3%, and the Pt content was 0.004%.

Comparative example 3: (the carrier and the production method were the same as in example 3 except that Ni was not supported)

And (3) preparing a catalyst:

a commercial bimodal pore distribution spherical alumina support was 4mm in diameter. After roasting for 4 hours at 1100 ℃, the pore size distribution ranges are 25-40 nm and 100-280 nm, the water absorption rate is 55%, and the specific surface area is 30.16m ² 100g of the carrier was weighed.

(1) 8.85g of copper nitrate was weighed and dissolved in 75mL of deionized water, 33g of cyclohexane was added, 17.6g of Triton X-100 was added, 17.2g of n-amyl alcohol was added, and the mixture was stirred well to form a microemulsion. The carrier is added into the prepared microemulsion to be immersed for 30min, residual liquid is filtered, dried at 40 ℃ and baked at 600 ℃ for 6h.

Obtaining a semi-finished catalyst E1;

(2) Weighing 0.117g of palladium chloride, dissolving in 120mL of deionized water, adjusting the pH to 2.5, adding the semi-finished catalyst E1 into a Pd salt solution, soaking and adsorbing for 30min, drying at 100 ℃, and roasting at 550 ℃ for 6h to obtain a semi-finished catalyst F1;

(3) 0.93g of cerium nitrate and 0.0084g of chloroplatinic acid are taken and dissolved in 50mL of deionized water, the pH value is adjusted to 3.0, then the semi-finished catalyst F1 is immersed into the prepared solution, after the solution is completely absorbed, the solution is dried for 5 hours at 120 ℃, and baked for 5 hours at 550 ℃, thus obtaining the finished catalyst.

the content of the element was measured by atomic absorption spectrometry to obtain a catalyst prepared in example 1, wherein the Pd content was 0.07%, the Cu content was 3%, the Ce content was 0.3%, and the Pt content was 0.004%.

The implementation effect is as follows:

working condition 1

Reduction of the catalyst: reducing gas: hydrogen, space velocity of reduction: 100h ^-1 The temperature was 380℃and maintained for 4h.

And (2) raw materials of carbon: acetylene 0.7% (v/v), ethylene 70% (v/v), carbon three 3% (v/v),

crude hydrogen: hydrogen content 20% (v/v), methane content 79.8% (v/v), CO content 0.1% (v/v).

The content of primary CO in the hydrogenated material is 39ppm;

the process conditions are as follows: space velocity of material 2000/h, operating pressure 3.0MPa, catalyst loading, 100mL

Two-stage hydrogenation process, wherein the inlet temperature of one stage is 50 ℃, and the mole ratio of hydrogen to alkyne is 1.1; the second stage inlet temperature was 70℃and the hydrogen/alkyne molar ratio was 1.5

The reaction results are shown in Table 4.

TABLE 4 reaction results

TABLE 5 catalyst coking levels for 1000 hours

	One section of	Two-stage
			Example 3	3.7	1.6
Comparative example 3	11.4	4.1

As shown in Table 4, the catalyst of example 3 and comparative example 3 showed a slight difference in the first stage outlet under the condition of working condition 1 in 24 hours of the first period, probably because the catalyst of example 3 increased the selectivity of the reaction in the presence of CO, and the Ni-Cu active center also had the selective hydrogenation function of acetylene, but the activity was still different from Pd. Although the mole ratio of the second-stage hydrogen to the alkyne is low, the selectivity of the initial reaction is good, and the acetylene content of the second-stage outlet is qualified. After 1000 hours, the catalyst of comparative example 3 had been significantly reduced in acetylene conversion in the first reactor and the acetylene content at the outlet of the second reactor was significantly exceeded. After 1000 hours, the catalyst of comparative example 3 coked quite severely in the primary reactor, 3 times the amount of coked catalyst of example 3.

After 5 regenerations, the performance of the catalysts of example 3 and comparative example 3 was reduced, but the catalysts were still in a range that could be used continuously.

Working condition 2

And (2) raw materials of carbon: acetylene 0.8% (v/v), ethylene 70% (v/v), carbon three 3% (v/v),

Crude hydrogen: hydrogen content 40% (v/v), methane content 59.8% (v/v), CO content 0.2% (v/v).

The content of primary CO in the hydrogenated material is 48ppm;

the process conditions are as follows: the space velocity of the material is 3000/h, the operating pressure is 3.0MPa, the catalyst loading amount is 100mL

Two-stage hydrogenation process, wherein the inlet temperature of one stage is 55 ℃, and the mole ratio of hydrogen to alkyne is 1.2; the second stage inlet temperature was 80℃and the hydrogen/alkyne molar ratio was 1.5

The reaction results are shown in Table 6.

TABLE 6 reaction results

TABLE 7 coking Process for 1000 hours catalyst

	One section of	Two-stage
			Example 3	3.2	1.5
Comparative example 3	9.9	3.1

As shown in Table 6, in the condition of 2, the catalyst of example 3 and the catalyst of comparative example 3 have a slight difference in the first stage outlet at the initial stage of the reaction, probably because the catalyst of example 3 improves the selectivity of the reaction in the presence of CO, and the active site of Ni-Cu has the selective hydrogenation function of acetylene, but the activity is still mainly dependent on Pd. Because the acetylene content at the inlet of the second section is low, the selectivity of the initial reaction is good, and the acetylene content at the outlet of the second section is qualified. After 1000 hours, the catalyst of comparative example 3 was found to have a second stage outlet acetylene content exceeding the standard. After 1000 hours, the catalyst of comparative example 3 had coked quite severely in the primary reactor, 3 times the amount of coked catalyst of example 3, and the primary outlet acetylene content was significantly reduced in condition 2 compared to condition 1, for 3 reasons: 1) The CO content is reduced; 2) The molar ratio of hydrogen to alkyne is increased; 3) The temperature increases. As the CO content is reduced, the mole ratio of hydrogen to alkyne is improved, the hydrogen acylation reaction product and the hydrodimerization product are less, the catalyst of comparative example 3 is less in coking under the working condition 2, and the content of acetylene at the second-stage outlet is also obviously reduced.

Example 4

And (3) a carrier: a commercially available bimodal pore distribution spherical alumina carrier was used, 3mm in diameter. After 4 hours of roasting at 1070 ℃, the bimodal pore diameter distribution range is 20-35 nm and 90-180 nm, the water absorption rate is 53%, and the specific surface area is 39.85m ² And/g. 100g of the carrier was weighed.

And (3) preparing a catalyst:

(1) Weighing 6.22G of anhydrous nickel nitrate, 11.81G of copper nitrate, dissolving in 60mL of deionized water, adding 30G of normal hexane, adding 18G of CABT, adding 18G of normal butanol, fully stirring to form a microemulsion, dipping 100G of high-temperature roasted carrier into the prepared microemulsion, shaking for 90min, filtering out residual liquid, drying at 60 ℃, and roasting at 550 ℃ for 6h to obtain a semi-finished catalyst G;

(2) Weighing 0.133G of palladium chloride, dissolving in 100mL of deionized water, adjusting the pH to 1.8, soaking the semi-finished catalyst G in the prepared Pd salt solution for 60min, drying at 100 ℃, and roasting at 400 ℃ for 6 hours to obtain a semi-finished catalyst H;

(3) Taking 0.93g of cerium nitrate and 0.0042g of platinum nitrate, dissolving in 52mL of deionized water, adjusting the pH to 2.5, immersing the obtained semi-finished catalyst H into the prepared solution, drying at 120 ℃ for 5 hours after the solution is fully absorbed, and roasting at 400 ℃ for 5 hours to obtain the desired catalyst.

Dynamic light scattering measurement the particle size of the microemulsion emulsion prepared in step (1) was 50.36nm.

The catalyst prepared by atomic absorption spectrometry was found to have a Pd content of 0.08%, a Ni content of 2%, a Cu content of 4%, a Ce content of 0.3% and a Pt content of 0.002% in example 4.

Comparative example 4

The same carrier as in example 4 was used and the preparation conditions were the same except that no cerium was supported

And (3) preparing a catalyst:

(1) Weighing 6.22G of anhydrous nickel nitrate, 11.81G of copper nitrate, dissolving in 60mL of deionized water, adding 30G of normal hexane, adding 18G of CABT, adding 18G of normal butanol, fully stirring to form a microemulsion, dipping 100G of high-temperature roasted carrier into the prepared microemulsion, shaking for 90min, filtering out residual liquid, drying at 60 ℃, and roasting at 550 ℃ for 6h to obtain a semi-finished catalyst G1;

(2) Weighing 0.133G of palladium chloride, dissolving in 100mL of deionized water, adjusting the pH to 1.8, soaking the semi-finished catalyst G1 in the prepared Pd salt solution for 60min, drying at 100 ℃, and roasting at 400 ℃ for 6 hours to obtain a semi-finished catalyst H1;

(3) Dissolving 0.0042g of platinum nitrate in 52mL of deionized water, regulating the pH to 2.5, immersing the obtained semi-finished catalyst H1 into the prepared solution, drying at 120 ℃ for 5 hours after the solution is fully absorbed, and roasting at 400 ℃ for 5 hours to obtain the required catalyst;

The catalyst prepared by atomic absorption spectrometry was found to have a Pd content of 0.08%, a Ni content of 2%, a Cu content of 4% and a Pt content of 0.002% in example 4.

The implementation effect is as follows:

reduction of the catalyst: reducing gas: hydrogen, space velocity of reduction: 100h ^-1 The temperature was 390℃and maintained for 4h.

And (2) raw materials of carbon: acetylene 1% (v/v), ethylene 90% (v/v), carbon three 0.1% (v/v),

crude hydrogen: hydrogen content 50% (v/v), methane content 49.9% (v/v), CO content 0.1% (v/v).

The content of primary CO in the hydrogenated material is 20ppm;

the process conditions are as follows: space velocity of material 1000/h, operating pressure 2.5MPa, catalyst loading, 100mL

Two-stage hydrogenation process, wherein the inlet temperature of one stage is 65 ℃, and the mole ratio of hydrogen to alkyne is 1.5; the second stage inlet temperature was 75℃and the hydrogen/alkyne molar ratio was 2.0

The process parameters are shown in Table 8.

TABLE 8 reactor conditions for each stage

	One section of	Two-stage
			Molar ratio of hydrogen to alkyne	1.5	2.0
Inlet temperature (DEG C)	65	75

The evaluation results are shown in Table 9.

TABLE 9 reaction results

As shown in Table 9, at the beginning of the first cycle operation, the reactor outlet of example 4 was at a stage of 0 acetylene content and the reactor outlet of comparative example 4 was at 0.5ppm acetylene content, probably because at a high Pd content, 390 ℃ reduction temperature, some of the catalyst of comparative example 4 had accumulated in the absence of Ce, resulting in a decrease in the initial selectivity of the catalyst.

After 1000 hours, the coking amount of the first-stage catalyst of the comparative example 4 is slightly higher than that of the example 4, but the coking amount is not much, but the acetylene content of the first-stage outlet is obviously higher than that of the example 4, the second-stage outlet of the comparative example 4 has trace acetylene, the example 4 is still 0, and the intrinsic selectivity of the catalyst is still reflected.

After 5 regenerations, the catalyst of comparative example 4 has disqualified acetylene content at the outlet of the second-stage reactor in the initial operation period, and the difference between the two is only 0.5, which shows that the existence of Ce is very important for maintaining the stability of the catalyst structure during catalyst regeneration and high-temperature reduction.

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 selective hydrogenation method of a carbon two-fraction is characterized in that the carbon two-fraction enters a reactor for gas-phase hydrogenation to remove acetylene, and the inlet of the reactor is provided with a catalyst bed for the catalyst bedThe temperature is 40-120 ℃, the pressure of the reactor is 1.5-3.0 MPa, and the gas volume space velocity is 1000-6000 h ^-1 The hydrogen needed for the reaction is derived from crude hydrogen; the catalyst used for the gas phase hydrogenation acetylene removal reaction comprises a carrier and an active component, wherein the carrier comprises Al ₂ O ₃ The carrier has bimodal pore size distribution, the pore size is respectively 20-50 nm and 90-500 nm, the active component comprises Pd, ni, cu, pt, ce, the catalyst contains 0.065-0.08% of Pd, 1-5% of Ni,2-5% of Cu,0.1-0.5% of Ce and 0.001-0.01% of Pt by taking the mass of the catalyst as 100%, wherein the loading of Ni and Cu adopts a microemulsion mode, the particle size of the microemulsion is 50-500 nm, and the loading of Pd, pt and Ce adopts a solution mode.

2. The method for selectively hydrogenating a carbon two fraction according to claim 1, wherein the carbon two fraction is a carbon two fraction at the top of a deethanizer, and the reactor is a fixed bed reactor.

3. The selective hydrogenation process of two-carbon fraction according to claim 1, wherein the volume content of ethylene in the two-carbon fraction is 60-90%, the volume content of acetylene is 0.1-1.0%, and the volume content of three-carbon is 0.01-5%.

4. The selective hydrogenation process of carbon two fractions according to claim 1, wherein the volume content of CO in the crude hydrogen is 0.1-1% and the volume content of hydrogen is 20-70%.

5. The selective hydrogenation process of carbon two fractions according to claim 2, wherein the reactor is a single stage reactor having an inlet hydrogen/alkyne molar ratio of from 1.3 to 2.0; or the reactor is a two-stage reactor, the mole ratio of hydrogen to alkyne at the inlet of the first-stage reactor is 1.1-1.5, and the mole ratio of hydrogen to alkyne at the inlet of the second-stage reactor is 1.3-2.0.

6. The selective hydrogenation process of carbon two fractions according to claim 1, wherein Pt and Ce are simultaneously supported and carried out after Pd is supported and calcined.

7. The selective hydrogenation process of two carbon fractions according to claim 1, wherein the solution loading means that the precursor of the active component is formulated into a solution and then the precursor of the active component is loaded on the carrier by impregnating the carrier; the microemulsion loading means that the precursor of the active component is prepared into microemulsion, and then the precursor of the active component is loaded on the carrier by a carrier impregnation method.

8. The selective hydrogenation process of carbon two fractions according to claim 7, wherein the microemulsion is formulated by: dissolving precursors of Ni and Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; wherein the weight ratio of the surfactant to the cosurfactant is 1-1.2, the weight ratio of the water phase to the oil phase is 2.0-3.0, and the weight ratio of the surfactant to the oil phase is 0.15-0.6.

9. The selective hydrogenation process of carbon two fractions according to claim 1, wherein the catalyst preparation process comprises:

And 3, dissolving a Pt precursor and a Ce precursor in water, adjusting the pH to 1.0-3.0, adding a semi-finished catalyst B, dipping, drying and roasting to obtain the required catalyst.

10. The selective hydrogenation process of carbon two fractions according to claim 1, wherein the catalyst preparation process comprises:

step 3, dissolving a precursor of Ni and a precursor of Cu in water, adding an oil phase, a surfactant and a cosurfactant, and fully stirring to form microemulsion; the weight ratio of the surfactant to the cosurfactant is 1-1.2, the weight ratio of the water phase to the oil phase is 2.0-3.0, and the weight ratio of the surfactant to the oil phase is 0.15-0.6; and adding the semi-finished catalyst B into the prepared microemulsion for soaking, drying and roasting to obtain the required catalyst.