A process for the selective hydrogenation of carbon dioxide fractions

Abstract

The application provides a selection method of carbon di-fragment, and the reaction process conditions are as follows: reactor inlet temperature is 55-110 DEG C, reaction pressure is 1.5-3.0 MPa, gas volume space velocity is 1000-5000 h ‑1 : the hydrogen at the reactor inlet is from crude hydrogen, the CO content in the crude hydrogen is 0.1%-1%, the hydrogen / acetylene volume ratio is 1.3-3.0, the catalyst used in the hydrogenation method is a catalyst with non-noble metal Fe as the main active component, through the combination of the catalyst and the reaction process conditions, the sensitivity of the reaction temperature to the CO content in the hydrogenation process is reduced, and the catalyst cost and the coking amount of the catalyst are reduced while the selection hydrogenation efficiency of the carbon di-fragment is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogenation, and particularly relates to a method for selectively hydrogenating a C2 fraction. BACKGROUND

[0002] Polymer-grade ethylene production is the leader of the petrochemical industry, and polymer-grade ethylene is the most basic raw material for downstream polymerization devices. The selective hydrogenation of acetylene has an extremely important influence on the ethylene industry. In addition to ensuring that the acetylene content at the outlet of the hydrogenation reactor meets the standard, the excellent selectivity of the catalyst can make ethylene generate as little ethane as possible, which is of great significance to improving the ethylene yield of the entire process and improving the economic benefits of the device.

[0003] The cracking C2 fraction contains acetylene. In the production of polyethylene, a small amount of acetylene in ethylene can reduce the activity of the polymerization catalyst and make the physical properties of the polymer worse, so the acetylene content in ethylene must be reduced to a certain limit to be used as a monomer for synthesizing high polymers. Therefore, acetylene separation and conversion is one of the important processes in the ethylene device process.

[0004] Catalytic selective hydrogenation in an ethylene device includes pre-hydrogenation and post-hydrogenation. Acetylene pre-hydrogenation and post-hydrogenation refer to the position of the acetylene hydrogenation reactor relative to the demethanizer. The hydrogenation reactor is located before the demethanizer for pre-hydrogenation, and the hydrogenation reactor is located after the demethanizer for post-hydrogenation. The advantage of the post-hydrogenation process is that the hydrogenation process has many control means, is not easy to fly, and is easy to operate. However, the disadvantage is that the catalyst is easy to coking, and the catalyst regeneration is relatively frequent. The reason is that in the hydrogenation process, due to the small amount of hydrogen gas, the hydrogenation dimerization reaction of acetylene is easy to occur, 1,3-butadiene is generated, and further generates oligomers with a wide molecular weight, commonly known as "green oil". The green oil is adsorbed on the surface of the catalyst, and further forms coking, blocks the catalyst pores, and reduces the activity and selectivity of the catalyst. Therefore, in the C2 hydrogenation reaction, the generation of green oil and the coking of the catalyst are important factors affecting the long-term operation of the device.

[0005] To solve the problem, Chinese patent document CN112679301B discloses a carbon fraction selective hydrogenation method. The hydrogenation raw material comes from a deethanizer, and the hydrogen gas is crude hydrogen. In the preparation of the catalyst, a W / O type microemulsion with a particle size larger than the small pores of the carrier is used. The microemulsion contains metal salts of nickel, copper and palladium. Because the kinetic volume of the microemulsion is larger than the size of the small pores, the microemulsion particles can only enter the large pores of the carrier. Part of the Pd is loaded by a solution method. Due to the siphon effect of the small pores, this part of Pd is located in the small pores. In the preparation method of the catalyst, after loading Ni-Cu by the microemulsion method, in order to reduce the reduction temperature of the Ni-Cu active center, part of the Pd is loaded on the outer surface of the Ni-Cu active center by the microemulsion method. However, the reduction temperature of Ni-Cu often reaches about 350°C. At this temperature, the Pd atoms in the reduced state are prone to aggregation, which greatly reduces the activity of the catalyst. 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 the emulsion method to form a Ni-Cu-Pd active center, and the reduction temperature can be reduced to 150°C. Because the palladium is loaded twice, the content of palladium in the catalyst is higher than that of the commonly used catalyst, which is increased by more than 50%, which greatly increases the cost of the catalyst and makes the catalyst preparation process more complex. In addition, since palladium needs to be loaded twice by different methods, the microemulsion used for loading palladium is basically the same as that used for loading nickel-copper, and this part of palladium does not directly contribute to the hydrogenation of acetylene. Since the main active component of the above hydrogenation catalyst is the noble metal Pd, the loading amount is large, which makes the cost of the catalyst high.

[0006] Chinese patent document CN1129606A discloses a hydrocarbon conversion catalyst and a preparation method. The carrier catalyst includes alumina, nickel oxide, iron oxide, etc. The catalyst includes two kinds of pores, one for increasing the surface of the catalytic reaction, and the other for facilitating diffusion. CN101433842A discloses a hydrogenation catalyst. The catalyst has a bimodal pore distribution, with a most probable radius of 2-50 nm for the small pores and a most probable radius of 100-400 nm for the large pores. Since the catalyst has a bimodal pore distribution, it has good hydrogenation activity and good selectivity, and the ethylene increment is large. Although the carrier with large pore structure can improve the selectivity, the large molecules generated by polymerization and chain growth reaction are also easily accumulated in the large pores of the carrier, causing the catalyst to coking and deactivation, affecting the service life of the catalyst.

[0007] Chinese patent document CN104098425A discloses a carbon fraction selection method, a hydrogenation method using a catalyst, an active component Pd, Ag is loaded by using a water solution impregnation method, and Ni is loaded by using a W / O microemulsion impregnation method. After the method is used, Pd / Ag and Ni are located in different pore channels with different pore diameters, green oil generated in the reaction is saturated hydrogenated in a large pore, and the amount of catalyst coking is reduced. Before the catalyst is put into operation, the catalyst needs to be reduced. Generally, the reduction temperature of a noble metal catalyst is low, but the reduction temperature of Ni often needs to reach about 500 DEG C. At the temperature, Pd atoms in a reduced state are prone to aggregation, so that the catalyst activity is reduced by more than 30%, the amount of active components needs to be greatly increased to compensate for the activity loss, but the selectivity is also reduced.

[0008] If CO is contained in a hydrogenation raw material, hydrogenation process will have a hydrogenation reaction of acylation, and aldehydes, ketones, acids and the like will be generated. These fractions are more easily adsorbed on an alumina carrier, and the process of green oil forming coking will be accelerated. However, in the above disclosed catalyst, the main active component is Pd, and Ni is mainly used for hydrogenation of by-products. These components do not have the effect of carbonyl hydrogenation, that is, the coking rate of a carbon two hydrogenation catalyst with CO participating in the hydrogenation process cannot be effectively reduced. Since CO is brought into the hydrogenation process, CO is a temporary poison of Pd, which reduces the hydrogenation activity of Pd, and the content of noble metal Pd needs to be further increased, so that the cost of the catalyst is more expensive. SUMMARY

[0009] The purpose of the present application is to provide a carbon fraction selective hydrogenation method, which uses a non-noble metal Fe as a main active component of a catalyst, and reduces the sensitivity of the reaction temperature to the CO content in the hydrogenation process. While ensuring the hydrogenation efficiency of the carbon two hydrogenation fraction, the cost of the catalyst and the amount of coking of the catalyst are reduced.

[0010] To achieve the above purpose, the present application adopts the following technical solutions:

[0011] A carbon fraction selective hydrogenation method, carbon two fractions and hydrogen are subjected to selective hydrogenation reaction in a hydrogenation reactor containing a catalyst, and the process conditions of the selective hydrogenation reaction are as follows: the reactor inlet temperature is 55-110 DEG C, the reaction pressure is 1.5-3.0 MPa, the gas volume space velocity is 1000-5000 h -1 -1; the hydrogen / oxygen volume ratio at the reactor inlet is 1.3-3.0, and the hydrogen is derived from crude hydrogen, the CO content in the crude hydrogen is 0.1%-1%,

[0012] The catalyst used in the selective hydrogenation reaction is as follows: the carrier is alumina or mainly alumina, the specific surface area is 15-40 m 2The catalyst has a bimodal pore size distribution, with a small pore size of 20-60 nm and a large pore size of 70-600 nm; the active components include Pd, Ni and Fe, the Pd is loaded by microemulsion method and solution method, the Ni is loaded by microemulsion method, and the Fe is loaded by solution method; and the Pd loaded by solution method is loaded after the Fe loaded by solution method, and the Pd loaded by microemulsion method is loaded after the Ni loaded by microemulsion method; the Pd and Ni loaded by microemulsion method are located in the large pores, and the Fe and Pd loaded by solution method are located in the small pores;

[0013] The content of Ni is 1.0%-5%, the content of Fe is 1%-2.5%, and the content of Pd is 0.007%-0.018%, based on 100% of the mass of the carrier; wherein the content of Pd loaded by solution method is 0.005%-0.01%, and the content of Pd loaded by microemulsion method is 0.002%-0.008%;

[0014] The catalyst is reduced at 180-230 ℃ (preferably for 8-12 h) before being put into the selective hydrogenation reaction.

[0015] In the selective hydrogenation method provided by the application, Fe in the catalyst is the main active component for selective hydrogenation. In the hydrogenation process, CO in the crude hydrogen also participates in the reaction, mainly undergoing formylation reaction with hydrogen and olefins to generate compounds containing carbonyl groups. The adsorption strength of these compounds containing carbonyl groups on the alumina is higher than that of olefins, and the compounds containing carbonyl groups stay on the catalyst for a longer time, thereby reducing the hydrogenation activity of Fe.

[0016] Moreover, the catalyst needs to be reduced before the hydrogenation reaction, and the Pd and Ni components need to be reduced from the oxidized state to the metallic state under the action of hydrogen. The reduction temperature of the oxide of Pd is not higher than 150 ℃, and the reduction temperature of the oxide of Ni is 350-400 ℃, which is too high for Pd and easily causes the aggregation of active centers to form larger active centers, thereby reducing the activity selectivity of the hydrogenation reaction.

[0017] Therefore, two key problems need to be solved in the hydrogenation process: 1) the hydrogenation activity problem of Fe; and 2) the growth of Pd particles caused by the reduction temperature of 350-400 ℃.

[0018] The present inventors have found through research that the hydrogenation activity is greatly improved after a small amount of Pd is loaded by solution method after Fe is loaded by solution method, and it is speculated that the small amount of Pd loaded by solution method plays a role in accelerating the hydrogenation rate, thereby accelerating the hydrogenation reaction. The present inventors have also found that the reduction temperature of NiO can be reduced to 180-230 ℃ after a small amount of Pd is loaded by microemulsion method after Ni is loaded by microemulsion method.

[0019] The hydrogenation method provided by the present application adopts non-noble metal iron as the main active component and a catalyst with a carrier having a bimodal distribution of pore sizes (large pores loaded with Ni and a small amount of Pd, and small pores loaded with Fe and a small amount of Pd), and the hydrogenation material contains hydrogen from crude hydrogen, methane and CO in addition to acetylene, ethylene and ethane. In the hydrogenation process, the selective hydrogenation of acetylene mainly occurs in the small pores loaded with Fe and a small amount of Pd, and the by-products (such as green oil and derivatives of butadiene) generated in the hydrogenation reaction are more likely to enter the large pores of the catalyst due to their larger volume, and under the action of the Ni active center, the double bonds of the green oil fraction are saturated and hydrogenated into alkanes, and no polymerization reaction occurs, thereby greatly reducing the coking rate.

[0020] Optionally, in the selective hydrogenation method of the carbon diene fraction provided by the present application, the carbon diene fraction is from the top of the previous deethanizer, and the ethylene content is 60% to 90% and the acetylene content is 0.1% to 1.5% based on 100% of the total volume of the carbon diene fraction.

[0021] Optionally, in the selective hydrogenation method of the carbon diene fraction provided by the present application, the hydrogenation reactor is a fixed bed hydrogenation reactor, and the fixed bed reactor is an adiabatic or isothermal reactor.

[0022] Optionally, in the selective hydrogenation method of the carbon diene fraction provided by the present application, the selective hydrogenation reaction is single-stage hydrogenation, two-stage hydrogenation or three-stage hydrogenation; in the two-stage hydrogenation, no hydrogen is supplied in the second stage; and in the three-stage hydrogenation, no hydrogen or a small amount of hydrogen is supplied in the third stage.

[0023] Optionally, in the selective hydrogenation method of the carbon diene fraction provided by the present application, the microemulsion method refers to the traditional impregnation method, and the impregnation solution is a microemulsion; and the solution method refers to the traditional impregnation method, and the impregnation solution is a solution. The process of the microemulsion method recommended by the present application for loading Ni or the microemulsion method for loading Pd includes the following steps: dissolving a precursor salt of Ni or a precursor salt of Pd in water to obtain an aqueous phase, then adding an oil phase, a surfactant and a co-surfactant to the aqueous phase, and stirring to form a microemulsion.

[0024] Optionally, in the above-mentioned selective hydrogenation method of carbon di- fraction, the particle size of the microemulsion is not less than the maximum pore size of the small pores of the carrier and not more than the maximum pore size of the large pores, for example, the particle size of the microemulsion is 60-600 nm. For a specific catalyst carrier with a bimodal pore size distribution, the pore size of the small pores and the pore size of the large pores are in respective size ranges, and the particle size of the microemulsion not less than the maximum pore size of the small pores and not more than the maximum pore size of the large pores means that the particle size of the microemulsion prepared for loading is not less than the upper limit of the pore size range of the small pores of a specific catalyst carrier and not more than the upper limit of the pore size range of the large pores of the catalyst carrier. Preferably, the particle size of the microemulsion is greater than 60 nm (including 60 nm) and less than 600 nm (including 600 nm).

[0025] The particle size of the microemulsion is greater than the pore size of the small pores and less than the maximum pore size of the large pores. Due to the space resistance, these components can only enter the large pores, and thus in the small and large pores of the catalyst, active centers with different hydrogenation effects are formed. The large pores contain active centers of Ni, which have good hydrogenation saturation effect on green oil molecules, so that the green oil molecules entering the large pores are no longer polymerized, and thus gradually move out of the reactor and are not easy to form coking.

[0026] In the above-mentioned microemulsion method for loading Ni or the microemulsion method for loading Pd recommended by the present application, the mass ratio of the aqueous phase to the oil phase is 2.2-3.5, the mass ratio of the surfactant to the oil phase is 0.12-0.55, and the mass ratio of the surfactant to the co-surfactant is 1.0-1.3.

[0027] Optionally, in the above-mentioned microemulsion method for loading Ni or the microemulsion method for loading Pd recommended by the present application, the oil phase is a C6-C8 saturated alkane or a cycloalkane, preferably cyclohexane or n-hexane.

[0028] The surfactant is an ionic surfactant and / or a non-ionic surfactant, preferably a non-ionic surfactant, more preferably polyethylene glycol octylphenyl ether or hexadecyl trimethyl ammonium bromide.

[0029] The co-surfactant is an organic alcohol; preferably a C4-C6 alcohol, more preferably n-butanol and / or n-pentanol.

[0030] Optionally, in the above-mentioned selective hydrogenation method of carbon di- fraction, the sequence of loading the active components into the carrier comprises the following steps:

[0031] microemulsion loading of Ni, solution loading of Fe, solution loading of Pd, microemulsion loading of Pd; or

[0032] microemulsion loading of Ni, solution loading of Fe, microemulsion loading of Pd, solution loading of Pd; or

[0033] solution method Fe, solution method Pd, microemulsion method Ni, microemulsion method Pd, solution method Fe, solution method Pd.

[0034] microemulsion method Ni, microemulsion method Pd, solution method Fe, solution method Pd.

[0035] Specifically, the preparation of the catalyst comprises the following steps:

[0036] (1) dissolving a precursor salt of Ni in water, adding an oil phase, a surfactant and a co-surfactant, and fully stirring to form a microemulsion; the conditions for preparing the microemulsion are as follows: the weight ratio of the surfactant to the co-surfactant is 1-1.3, the weight ratio of the water phase to the oil phase is 2.2-3.5, and the weight ratio of the surfactant to the oil phase is 0.12-0.55; adding the calcined carrier into the prepared microemulsion for impregnation, drying after the microemulsion is completely absorbed, and calcining at 400-600°C to obtain a semi-finished catalyst A;

[0037] (2) dissolving a precursor salt of Fe in deionized water, the volume of the solution being equivalent to the water absorption capacity of the carrier, adding the semi-finished catalyst A into the prepared solution, drying after the solution is completely absorbed, and calcining at 250-600°C to obtain a semi-finished catalyst B;

[0038] (3) dissolving a precursor salt of Pd in water, the volume of the solution being equivalent to the water absorption capacity of the carrier, adjusting the pH to 1.2-2.7, adding the semi-finished catalyst B into the salt solution of Pd, drying after the solution is completely absorbed, and calcining at 400-550°C to obtain a semi-finished catalyst C;

[0039] (4) dissolving a precursor salt of Pd in water, adding an oil phase, a surfactant and a co-surfactant, and fully stirring to form a microemulsion; the conditions for preparing the microemulsion are as follows: the weight ratio of the surfactant to the co-surfactant is 1-1.3, the weight ratio of the water phase to the oil phase is 2.2-3.5, and the weight ratio of the surfactant to the oil phase is 0.12-0.55; adding the semi-finished catalyst C into the prepared microemulsion for impregnation, drying after the solution is completely absorbed, and calcining at 400-550°C to obtain the catalyst required by the semi-finished catalyst;

[0040] wherein, step (1) and step (2) can be interchanged; step (3) and step (4) can be interchanged, step (4) is after step (1), and step (3) is after step (2).

[0041] Optionally, the active component of the catalyst in the selective hydrogenation method of carbon dioxide fraction provided by the present application further comprises Ag, which is loaded by a solution method. Research shows that Ag can improve the selectivity of the hydrogenation process and also improve the anti-acetylene breakthrough capacity of the catalyst bed when the content of acetylene increases suddenly.

[0042] Optionally, in the selective hydrogenation method of carbon dioxide fraction provided by the present application, the content of Ag is 0.1% to 0.3% based on 100% of the mass of the carrier.

[0043] Specifically, the preparation method of the catalyst provided by the present application comprises the following steps:

[0044] (1) Dissolve the precursor salt of Ni in water, add an oil phase, a surfactant and a co-surfactant, fully stir to form a microemulsion, and control the particle size of the microemulsion to be 60 nm to 600 nm (including 60 nm and 600 nm); immerse the carrier in the prepared microemulsion for 0.5 to 4 hours, wait for the microemulsion to be completely absorbed and dried, and then calcine at 400 to 600°C to obtain a semi-finished catalyst A;

[0045] (2) Dissolve the precursor salt of Fe in water, and the amount of the solution is equivalent to the water absorption capacity of the carrier; adjust the pH to 1.5 to 2.5; then immerse the semi-finished catalyst A in the salt solution of Fe, wait for the solution to be completely absorbed, age, dry, and calcine at 250 to 600°C to obtain a semi-finished catalyst B;

[0046] (3) Dissolve the precursor salt of Pd in water, and the amount of the solution is equivalent to the water absorption capacity of the carrier; adjust the pH to 1.5 to 2.5; then immerse the semi-finished catalyst B in the salt solution of Pd, shake for 0.5 to 2 hours, dry, and calcine at 400 to 550°C to obtain a semi-finished catalyst C;

[0047] (4) Dissolve the precursor salt of Pd in water, add an oil phase, a surfactant and a co-surfactant, fully stir to form a microemulsion, and control the particle size of the microemulsion to be greater than 60 nm and less than 600 nm; immerse the semi-finished catalyst C in the prepared microemulsion, wait for the microemulsion to be completely absorbed and dried, and then calcine at 400 to 550°C to obtain a semi-finished catalyst D;

[0048] (5) Dissolve the precursor salt of Ag in water, and the amount of the solution is equivalent to the water absorption capacity of the carrier; then immerse the semi-finished catalyst D in the salt solution of Ag, wait for the solution to be completely absorbed, age, dry, and calcine at 400 to 550°C to obtain the desired catalyst;

[0049] In the above preparation steps, step (1) and step (2) can be interchanged, step (3) and step (4) can be interchanged, step (3) is after step (2), and step (4) is after step (1); and the loading process of step (5) can be performed in any order.

[0050] The precursor salt of the metal in each step is a soluble salt, which can be a nitrate salt, a chloride salt or other soluble salt, for example, the precursor salt of Pd can be selected from any one of soluble palladium salts such as palladium chloride, palladium nitrate and the like; the precursor salt of Ni can be selected from any one of soluble nickel salts such as nickel chloride, nickel nitrate and the like; the precursor salt of Fe is selected from any one of soluble iron salts such as ferric nitrate, ferric trichloride and the like.

[0051] The present application has the following beneficial effects:

[0052] The carbon fraction selective hydrogenation method provided by the present application has good hydrogenation selectivity and long-period operation characteristics, reduces the catalyst preparation cost, improves the target product yield, and greatly reduces the coking rate. Specifically, the main active component in the catalyst used is non-noble metal Fe, which reduces the content of Pd, reduces the cost of the catalyst, and makes the catalyst more convenient to produce and replace. Fe as the main active component has a lower adsorption strength of CO than the main active component Pd of the traditional catalyst, which reduces the sensitivity of the reaction temperature to the CO content in the hydrogenation process, and is conducive to the stability of the acetylene removal reaction. Moreover, due to the significant reduction of the catalyst cost, the reaction can be operated at a lower space velocity to ensure that the reaction result is qualified. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 Particle size distribution graph of the microemulsion prepared in step (3) of Example 2 of the present application. DETAILED DESCRIPTION

[0054] The present application will be described in detail below by way of examples. It is necessary to point out here that the following examples are only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application, and those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above content of the present application.

[0055] The specific experimental steps or conditions not specified in the examples can be performed according to the conventional experimental steps described in the literature in the art or the operation or conditions. The reagents or instruments not specified by the manufacturer are all conventional reagent products that can be obtained by purchase.

[0056] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

[0057] Analysis test method:

[0058] Specific surface area measurement, GB / T-5816; instrument: Tristar II 3020,

[0059] Metal content measurement, SH / T 0694-1999; instrument: AA240FS, to measure the content of Pd, Ag, Ni, Fe in the catalyst.

[0060] Ni, Pd microemulsion particle size distribution measurement, instrument: FC200

[0061] Evaluation of material composition measurement, GC-7890A gas chromatograph

[0062] The conversion rate and selectivity are calculated according to the following formula:

[0063] Acetylene conversion rate (%) = [(reactor inlet acetylene content-reactor outlet acetylene content) / reactor inlet acetylene content] x 100%

[0064] Ethylene selectivity = {2-[(reactor inlet hydrogen content-reactor outlet hydrogen content) / (reactor inlet acetylene content-reactor outlet acetylene content)]} x 100%

[0065] The initial conversion rate refers to the acetylene conversion rate within 24 hours from the start of the reactor feeding.

[0066] Coking amount = [(catalyst weight after reaction-catalyst weight before reaction) / reactor catalyst weight] x 100% The hydrogen and acetylene contents at the reactor outlet and inlet are measured by Agilent 7890A gas chromatograph.

[0067] Raw materials: nickel nitrate, palladium nitrate, iron nitrate, nickel chloride, ferric chloride, palladium chloride, n-hexane, cyclohexane, CTAB, Triton X-100, n-butanol, n-octanol, n-pentanol, analytical pure, all purchased from Shanghai National Pharmaceutical Group Corporation; alumina carrier purchased from Shandong Aluminum Industry Group.

[0068] The present application is further illustrated by the following examples, but it is not considered to be limited to this.

[0069] Example 1

[0070] Carrier: a commercially available bimodal pore size distribution spherical carrier was weighed, with an alumina content of 90%, a titanium oxide content of 10%, and a diameter of 4 mm. After calcination at 1100℃ for 4h, the pore size distribution range was 30-50nm and 200-450nm, the water absorption rate was 65%, the specific surface area was 30.18m 2 / g, and 100g of the carrier was weighed.

[0071] Catalyst preparation:

[0072] (1) 12.5 g of nickel nitrate was dissolved in 55 ml of deionized water, 19.6 g of cyclohexane, 5.89 g of Triton X-10, and 4.53 g of n-butanol were added, and the mixture was stirred to form a microemulsion. 100 g of the carrier was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, the mixture was dried at 60°C and calcined at 400°C for 5 hours to obtain a semi-finished catalyst A.

[0073] (2) 13.33 mg of palladium chloride was weighed and dissolved in 55 ml of deionized water, 19.6 g of cyclohexane, 5.89 g of Triton X-10, and 4.53 g of n-pentanol were added, and the mixture was stirred to form a microemulsion. The semi-finished catalyst A was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, the mixture was dried at 60°C and calcined at 550°C for 6 hours to obtain a semi-finished catalyst B.

[0074] (3) 7.27 g of ferric chloride was dissolved in 65 g of deionized water, and the semi-finished catalyst B was added to prepare a ferric salt solution. After the solution was completely absorbed, the mixture was dried at 100°C and calcined at 250°C for 8 hours to obtain a semi-finished catalyst C.

[0075] (4) 16.67 mg of palladium chloride was dissolved in 65 g of deionized water, and the pH was adjusted to 1.2. The semi-finished catalyst C was added to the prepared palladium salt solution, and aged for 4 hours. The mixture was dried at 120°C and calcined at 450°C for 6 hours to obtain the desired catalyst.

[0076] The particle size of the microemulsion prepared in steps (1) and (2) was 299.87 nm as determined by dynamic light scattering.

[0077] The content of Pd, Ni, and Fe in the catalyst was 0.018%, 4%, and 2.5%, respectively, based on the mass of the carrier, as determined by atomic absorption spectrometry. The content of Pd loaded by the solution method was 0.01%, and the content of Pd loaded by the emulsion method was 0.008%.

[0078] The catalyst was placed in a fixed bed reaction device before use, and reduced at 180°C for 8 hours in an atmosphere of hydrogen / nitrogen (V / V) = 1:1.

[0079] Comparative Example 1

[0080] Carrier: The same as in Example 1.

[0081] Catalyst preparation: Similar to Example 1, except that no Ni was loaded in Comparative Example 1.

[0082] Take 13.33 mg of palladium chloride and dissolve in 55 ml of deionized water, add 19.6 g of cyclohexane, 5.89 g of Triton X-10, 4.53 g of n-pentanol, and stir well to form a microemulsion. Dip the calcined carrier 100 g into the prepared microemulsion, and after the emulsion is completely absorbed, dry at 60°C. Calcine at 550°C for 6 hours to obtain the semi-finished catalyst B1.

[0083] (2) Take 7.27 g of ferric chloride and dissolve in 65 g of deionized water, then add the semi-finished catalyst B1 to prepare a Fe salt solution. After the solution is completely absorbed, dry at 100°C, and calcine at 250°C for 8 hours to obtain the semi-finished catalyst C1.

[0084] (3) Take 16.67 mg of palladium chloride and dissolve in 65 g of deionized water, adjust the pH to 1.2, then add the semi-finished catalyst C1 to the prepared Pd salt solution, and age for 4 hours. Dry at 120°C, and calcine at 450°C for 6 hours to obtain the desired catalyst.

[0085] The particle size of the microemulsion prepared in step (1) is 299.87 nm as determined by dynamic light scattering.

[0086] The Pd content of the catalyst is 0.018% and the Fe content is 2.5% based on the mass of the carrier as 100%, as determined by atomic absorption spectrometry. The Pd content loaded by the solution method is 0.01%, and the Pd content loaded by the emulsion method is 0.008%.

[0087] Before use, the catalyst is placed in a fixed bed reaction device and reduced at 180°C for 8 hours in an atmosphere of hydrogen / nitrogen (V / V) = 1:1.

[0088] Evaluation experiment

[0089] Working condition 1

[0090] Carbon di raw material: acetylene 0.1% (v / v), ethylene 60% (v / v), ethane 39% (v / v), methane 0.2% (v / v), carbon tri 0.7% (v / v).

[0091] Crude hydrogen: hydrogen content 90% (v / v), methane content 9% (v / v), CO content 1% (v / v).

[0092] Process conditions: material space velocity 1000 / h, operating pressure 2.2 MPa, reactor inlet temperature 55°C, hydrogen / acetylene 3.0, CO content in hydrogenated material 50 ppm.

[0093] Catalyst loading, 200 mL. The reaction results are shown in Table 1.

[0094] Table 1 Reaction results of working condition 1

[0095]

[0096] From Table 1, it can be seen that in the initial stage, there is no difference between Comparative Example 1 and Example 1, the acetylene content at the reactor inlet is less than 1 ppm; after 1000 hours, the acetylene content at the reactor outlet in the comparative example exceeds 3 ppm, which is already unqualified; after 2000 hours, the acetylene content at the reactor outlet in Comparative Example 1 reaches 12 ppm. The coking amount of the catalyst in Comparative Example 1 is more than twice that of Example 1, which is reflected in the selectivity, and the difference between the two is very obvious.

[0097] Working condition 2

[0098] Carbon two raw materials: acetylene 0.3% (v / v), ethylene 70% (v / v), ethane 29% (v / v), methane 0.3% (v / v), carbon three 0.4% (v / v).

[0099] Crude hydrogen: hydrogen content 85% (v / v), methane content 14.3% (v / v), CO content 0.7%.

[0100] Process conditions: material space velocity 3000 / h, reactor inlet temperature 60°C, operating pressure 1.5 MPa, hydrogen / acetylene 2.5, catalyst loading 150 mL, CO content in hydrogenated material 82 ppm. The reaction results are shown in Table 2 Table 2 Reaction results of working condition 2

[0101]

[0102] From Table 2, it can be seen that in working condition 2, as the acetylene content increases to 0.3%, the CO content in the material also increases to 52.5 ppm. During the 1000-hour evaluation, the acetylene content at the reactor outlet of Example 1 is always less than 1 ppm. While the comparative example is close to unqualified at 500 hours. After 2000 hours, the catalyst coking of Comparative Example 1 is close to 9%, and the catalyst coking of Example 1 also increases significantly relative to working condition 1, indicating that as the acetylene content and CO content increase, the amount of by-products also increases. Relative to working condition 1, the selectivity of Example and Comparative Example 1 has increased, indicating that the increase of CO content in the material can improve the selectivity of the reaction, but the coking amount increases relatively. The deactivation rate of the catalyst is accelerated. However, Comparative Example 1 does not load Ni, and its coking amount is much higher than that of Example 1, indicating that the loading of Ni has a significant effect on reducing the coking rate.

[0103] Example 2

[0104] Support: A commercially available bimodal pore size distribution spherical support was weighed, with an alumina content of 95% and a titania content of 5%, and a diameter of 4 mm. After calcination at 1120°C for 4 h, the pore size distribution ranges were 35-55 nm and 300-500 nm, the water absorption was 55%, and the specific surface area was 20.38 m 2 / g. 100 g of the support was weighed.

[0105] Catalyst preparation:

[0106] (1) 6.52 g of iron nitrate was dissolved in 55 g of deionized water, and the calcined support was added to prepare a Fe salt solution. After the solution was completely absorbed, drying was performed at 120°C, and calcination was performed at 300°C for 6 h to obtain semi-finished catalyst D.

[0107] (2) 13.33 mg of palladium chloride was dissolved in 55 g of deionized water, and the pH was adjusted to 1.6. The semi-finished catalyst D was added to the prepared Pd salt solution, and after the solution was completely absorbed, aging was performed for 10 h, drying was performed at 100°C, and calcination was performed at 500°C for 6 h to obtain semi-finished catalyst E.

[0108] (3) 9.38 g of nickel nitrate was dissolved in 48 ml of deionized water, 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol were added, and the mixture was stirred to form a microemulsion. The semi-finished catalyst E was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, drying was performed at 80°C, and calcination was performed at 400°C for 5 h to obtain semi-finished catalyst F.

[0109] (4) 6.67 mg of palladium chloride was dissolved in 48 ml of deionized water, 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol were added, and the mixture was stirred to form a microemulsion. The semi-finished catalyst F was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, drying was performed at 60°C, and calcination was performed at 400°C for 6 h to obtain the desired catalyst.

[0110] The particle size of the microemulsion prepared in steps (3) and (4) was 200.15 nm. Specifically, Figure 1 The particle size distribution graph of the microemulsion prepared in step (3) of the present embodiment can be seen from Figure 1 It can be seen that the particle size range of the microemulsion is 185-215 nm, and the number of microemulsions with a particle size of 185 nm and 215 nm is less than 0.05 compared with the number of peak particle sizes, indicating that the particle size distribution of the emulsion is very narrow.

[0111] The prepared catalyst was determined by atomic absorption spectrometry, and the Pd content was 0.012%, the Ni content was 3%, and the Fe content was 1.5% calculated on the basis of 100% of the carrier. Among them, the Pd content loaded by the solution method was 0.008%, and the Pd content loaded by the emulsion method was 0.004%.

[0112] Before use, it was placed in a fixed bed reaction device and reduced for 10 h at a temperature of 200°C using a mixed gas with a molar ratio of N2:H2=1:1.

[0113] Comparative Example 2

[0114] Carrier: the same as Example 2.

[0115] Catalyst preparation: similar to Example 2, the only difference being that no Fe was loaded in Comparative Example 2. Catalyst preparation:

[0116] (1) 13.33 mg of palladium chloride was weighed into 55 g of deionized water, the pH was adjusted to 1.6, and then 100 g of the calcined carrier was added to the prepared Pd salt solution. After the solution was completely absorbed, it was aged for 10 hours, dried at 100°C, and calcined at 500°C for 6 hours to obtain a semi-finished catalyst E1;

[0117] (2) 9.38 g of nickel nitrate was weighed into 48 ml of deionized water, 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol were added, and the mixture was stirred to form a microemulsion. The semi-finished catalyst E1 was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, it was dried at 80°C and calcined at 400°C for 5 h to obtain a semi-finished catalyst F1;

[0118] (3) 6.67 mg of palladium chloride was weighed into 48 ml of deionized water, 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol were added, and the mixture was stirred to form a microemulsion. The semi-finished catalyst F1 was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, it was dried at 60°C and calcined at 400°C for 6 hours to obtain the desired catalyst.

[0119] The particle size of the microemulsion prepared in steps (2) and (3) was determined by dynamic light scattering to be 200.18 nm.

[0120] The prepared catalyst was determined by atomic absorption spectrometry, and the Pd content was 0.012%, the Ni content was 3%, and the Fe content was 1.5% calculated on the basis of 100% of the carrier. Among them, the Pd content loaded by the solution method was 0.008%, and the Pd content loaded by the emulsion method was 0.004%.

[0121] Before use, it was placed in a fixed bed reaction device and reduced for 10 h at a temperature of 200°C using a mixed gas with a molar ratio of N2:H2=1:1.

[0122] Evaluation test

[0123] Carbon di-source: acetylene 0.6% (v / v), ethylene 85% (v / v), ethane 13.5% (v / v), methane 0.2% (v / v), carbon tri 0.7% (v / v).

[0124] Crude hydrogen: hydrogen content 80% (v / v), methane content 19.4% (v / v), CO content 0.6%.

[0125] Process conditions: material space velocity 3000 / h, operating pressure 2.0 MPa, reactor inlet temperature first reactor inlet temperature 65°C, hydrogen / acetylene 1.8, second reactor inlet temperature 110°C, CO content in hydrogenated material 148 ppm, catalyst loading 100 mL. The reaction results are shown in Tables 3 and 4.

[0126] Table 3 Reaction results

[0127]

[0128] Table 4 Coking amount after 1500 hours

[0129]

[0130]

[0131] From Table 3, it can be seen that the acetylene content at the outlet of the first and second reactors in Comparative Example 2 is much higher than that in Example 2, indicating that the acetylene removal activity of the catalyst is very poor without Fe loading, and Fe is the main active component for acetylene hydrogenation. The hydrogenation activity of the second reactor is higher than that of the first reactor in the comparative example, which may be due to the fact that the inlet temperature of the second reactor is much higher than that of the first reactor. A small amount of Pd loading is the active component for acetylene hydrogenation, but the loading is too small and its activity is insufficient. From Example 2, when the CO content reaches 148 ppm, the acetylene conversion rate of the first stage also reaches more than 70%, and the hydrogen / acetylene at the outlet of the first stage is higher than that at the inlet of the first stage, indicating that the selectivity of the first stage is excellent. Since the hydrogen / acetylene is increased after the first stage reaction, there is no need to add hydrogen to the second stage reactor, and there is still a lot of hydrogen remaining at the outlet of the second stage reactor, indicating that in the presence of a relatively high CO, even if the inlet temperature of the second reactor is as high as 110°C, hydrogen is not excessively hydrogenated with ethylene. After 1500 hours, the total selectivity still reaches 81.7%, indicating that the catalyst has good selectivity under the working conditions. From 24 hours to 1500 hours, the acetylene content at the outlet of the second stage of Example 2 is less than 1 ppm, indicating that the catalyst has good acetylene removal activity in the presence of CO.

[0132] As can be seen from Table 4, in Example 2, the amount of coking in the first stage is much higher than that in the second stage, because the amount of acetylene removal in the first stage is higher than that in the first stage; in Comparative Example 2, the amount of coking in the second stage is actually higher than that in the first stage, for the same reason, that is, the amount of acetylene removal in the second stage is higher than that in the first stage.

[0133] Example 3

[0134] Catalyst preparation:

[0135] A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After calcination at 1060℃ for 4 hours, the pore size distribution ranged from 20 to 40 nm and from 70 to 150 nm, respectively. The water absorption rate was 70%, and the specific surface area was 39.85 m². 2 / g, weigh out 100g of the carrier.

[0136] (1) Weigh 3.13g of nickel nitrate, dissolve it in 60ml of deionized water, add 27.28g of n-hexane, 15g of Triton X-100, and 15g of n-butanol, stir thoroughly to form a microemulsion, immerse 100g of the weighed carrier into the prepared microemulsion, and after the emulsion has been completely absorbed, dry it at 60℃ and calcine it at 600℃ for 5h to obtain the semi-finished catalyst G;

[0137] (2) Weigh 4.35g of ferric nitrate and dissolve it in 70g of deionized water. Then add the semi-finished catalyst G to the salt solution of Fe. After the solution is completely absorbed, dry it at 120℃ and calcine it at 600℃ for 4 hours to obtain the semi-finished catalyst H.

[0138] (3) Weigh 8.33 mg of palladium chloride and dissolve it in 70 g of deionized water, adjust the pH to 1.7, then add the semi-finished catalyst H to the salt solution of Pd, age for 18 hours, dry at 100℃, and calcine at 520℃ for 4 hours to obtain the semi-finished catalyst I.

[0139] (4) Weigh 3.33 mg of palladium chloride and dissolve it in 60 ml of deionized water. Add 27.28 g of n-hexane, 15 g of Triton X-100, and 15 g of n-butanol. Stir thoroughly to form a microemulsion. Impregnate the semi-finished catalyst I into the prepared microemulsion. After the emulsion has completely absorbed the catalyst, dry it at 60 °C and calcine it at 550 °C for 4 hours to obtain the semi-finished catalyst J.

[0140] (5) Weigh 0.47g of silver nitrate and dissolve it in 70g of deionized water. Then add the semi-finished catalyst J to the salt solution of Fe. After the solution is completely absorbed, age for 2 hours, dry at 120℃, and calcine at 500℃ for 4 hours to obtain the desired catalyst.

[0141] The particle size of the microemulsion prepared in steps (1) and (4) of the dynamic light scattering measurement is 60.23 nm.

[0142] The prepared catalyst was determined by atomic absorption spectrometry, and the Pd content was 0.007%, the Ni content was 1%, the Fe content was 1%, and the Ag content was 0.3%, wherein the Pd content loaded by the solution method was 0.005%, and the Pd content loaded by the emulsion method was 0.002%.

[0143] Before use, it was placed in a fixed bed reaction device and reduced for 8h at a temperature of 230°C using a mixed gas with a molar ratio of N2:H2=1:1.

[0144] Comparative Example 3

[0145] Support: the same as in Example 3.

[0146] Catalyst preparation: similar to Example 3, except that in Comparative Example 3, the solution method for loading Pd was not used.

[0147] Catalyst preparation:

[0148] (1) 3.13 g of nickel nitrate was weighed and dissolved in 60 ml of deionized water, 27.28 g of n-hexane, 15 g of Triton X-100, and 15 g of n-butanol were added, and the mixture was stirred to form a microemulsion. 100 g of the weighed support was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, it was dried at 60°C and calcined at 600°C for 5h to obtain a semi-finished catalyst G;

[0149] (2) 4.35 g of iron nitrate was weighed and dissolved in 70 g of deionized water, and then the semi-finished catalyst G was added to the Fe salt solution. After the solution was completely absorbed, it was dried at 120°C and calcined at 600°C for 4h to obtain a semi-finished catalyst H;

[0150] (3) 3.33 mg of palladium chloride was weighed and dissolved in 60 ml of deionized water, 27.28 g of n-hexane, 15 g of Triton X-100, and 15 g of n-butanol were added, and the mixture was stirred to form a microemulsion. The semi-finished catalyst I was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, it was dried at 60°C and calcined at 550°C for 4h to obtain a semi-finished catalyst I;

[0151] (4) 0.47 g of silver nitrate was weighed and dissolved in 70 g of deionized water, and then the semi-finished catalyst J was added to the Fe salt solution. After the solution was completely absorbed, it was aged for 2h, dried at 120°C, and calcined at 500°C for 4h to obtain the desired catalyst.

[0152] The particle size of the microemulsion prepared in steps (1) and (3) was 60.23 nm, which was determined by dynamic light scattering.

[0153] The prepared catalyst was determined by atomic absorption spectrometry, and the Pd content was 0.002%, the Ni content was 1%, the Fe content was 1%, and the Ag content was 0.3% based on 100% of the carrier.

[0154] Before use, it was placed in a fixed bed reaction device and reduced for 8 h at a temperature of 230°C using a mixed gas with a molar ratio of N2:H2=1:1.

[0155] Evaluation test

[0156] Operating conditions

[0157] Carbon di raw material: acetylene 1.5% (v / v), ethylene 90% (v / v), ethane 8% (v / v), methane 0.2% (v / v), carbon tri 0.3% (v / v).

[0158] Crude hydrogen: hydrogen content 85% (v / v), methane content 14.9% (v / v), CO content 0.1% (v / v).

[0159] The CO content in the hydrogenated material in the first stage was 20 ppm;

[0160] Process conditions: material space velocity 5000 / h, operating pressure 3.0 MPa, catalyst loading 100 mL

[0161] Three-stage hydrogenation process, first stage inlet temperature 55°C, hydrogen / acetylene 1.3; second stage inlet temperature 65°C, third stage inlet temperature 90°C. No hydrogen was provided for the second and third stages. The reaction results are shown in Table 5.

[0162] Table 5 Evaluation results

[0163]

[0164] From the results in Table 5, at the beginning of the reaction in Example 3, the hydrogen / acetylene at the outlet of the first reactor and the outlet of the second reactor were 1.54 and 3.13, respectively, both of which were higher than the hydrogen / acetylene at the inlet of the first reactor, indicating that in the overall bed, the higher the hydrogen / acetylene, the higher the temperature of the bed, and the more conducive to the conversion of acetylene. As long as the catalyst activity is sufficient, acetylene can be completely converted. That is, as long as the hydrogen / acetylene at the inlet of the first stage and the temperature of each stage are within the appropriate range, the second and third reactors of the hydrogenation process do not need to be provided with hydrogen.

[0165] From the beginning of the reaction to 1500 hours, the acetylene at the outlet of the third stage was always qualified, and after 1500 hours, the total selectivity could still reach a relatively high value of 84.0%.

[0166] In Comparative Example 3, no Pd was loaded in the solution during the preparation of the catalyst, and the activity of each reactor was much lower than that in Comparative Example 3. This indicates that the loading of a small amount of Pd indeed plays an important role in improving the hydrogenation activity of the catalyst.

[0167] Although there is still a large amount of acetylene remaining at the outlet of the three-stage reactor of Comparative Example 3, the total selectivity of the three stages is comparable to that of the examples, indicating that the addition of Pd does not affect the selectivity of hydrogenation.

[0168] Example 4

[0169] Support: A commercially available bimodal pore size distribution spherical alumina support with a diameter of 3 mm was used. After calcination at 1100°C for 4 h, the bimodal pore size distribution ranges from 25 to 45 nm and 100 to 220 nm, the water absorption is 65%, and the specific surface area is 35.34 m 2 / g. 100 g of the support was weighed.

[0170] Catalyst preparation:

[0171] (1) 5.56 g of nickel chloride was dissolved in 60 ml of deionized water, 26.08 g of cyclohexane, 13.04 g of Triton X-100, and 11.86 g of n-butanol were added, and the mixture was stirred to form a microemulsion. The weighed 100 g of the support was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, it was dried at 120°C and calcined at 550°C for 5 hours to obtain a semi-finished catalyst K;

[0172] (2) 10 mg of palladium chloride was weighed and dissolved in 60 ml of deionized water, 26.08 g of cyclohexane, 13.04 g of Triton X-100, and 11.86 g of n-butanol were added, and the mixture was stirred to form a microemulsion. The semi-finished catalyst K was immersed in the prepared microemulsion, and after the emulsion was completely absorbed, it was dried at 100°C and calcined at 550°C for 6 hours to obtain a semi-finished catalyst M;

[0173] (3) 0.157 g of silver nitrate was weighed and dissolved in 65 g of deionized water, and then the semi-finished catalyst M was added to the Ag salt solution. After the solution was completely absorbed, it was aged for 2 hours, dried at 80°C, and calcined at 550°C for 4 hours to obtain a semi-finished catalyst N;

[0174] (4) 8.70 g of ferric nitrate was weighed and dissolved in 65 g of deionized water, and then the semi-finished catalyst N was added to the prepared Fe salt solution. After the solution was completely absorbed, it was dried at 100°C and calcined at 550°C for 4 hours to obtain a semi-finished catalyst O;

[0175] (5) 10 mg of palladium chloride was weighed and dissolved in 65 g of deionized water, and the pH was adjusted to 2.7. Then the semi-finished catalyst O was added to the prepared Pd salt solution, aged for 4 hours, dried at 100°C, and calcined at 520°C for 6 hours to obtain the desired catalyst.

[0176] The particle size of the microemulsion prepared in step (1) and (2) was 100.12 nm.

[0177] The prepared catalyst was determined by atomic absorption spectrometry, and the Pd content was 0.012%, the Ni content was 2.5%, the Fe content was 2.0%, and the Ag content was 0.1% calculated as 100% of the carrier. Among them, the Pd content loaded by the solution method was 0.006%, and the Pd content loaded by the emulsion method was 0.006%.

[0178] Before use, it was placed in a fixed bed reaction device and reduced for 12 h at a temperature of 190°C with a mixed gas of a molar ratio of N2:H2=1:1.

[0179] Comparative Example 4

[0180] Carrier: the same as Example 4.

[0181] Catalyst: the same as Example 4.

[0182] Reduction: before use, it was placed in a fixed bed reaction device and reduced for 12 h at a temperature of 190°C with a mixed gas of a molar ratio of N2:H2=1:1.

[0183] Evaluation Test

[0184] Evaluation conditions of Example 4:

[0185] Carbon di raw material: acetylene 0.8% (v / v), ethylene 75% (v / v), ethane 23.5% (v / v), methane 0.3% (v / v), carbon three 0.4% (v / v).

[0186] Crude hydrogen: hydrogen content 80% (v / v), methane content 19.4% (v / v), CO content 0.6% (v / v).

[0187] Process conditions: material space velocity 4500 / h, operating pressure 2.5 MPa, catalyst loading amount, 100 mL

[0188] Two-stage hydrogenation process, first stage inlet temperature 90°C, hydrogen / acetylene 2.0; second stage inlet temperature 110°C,

[0189] The CO content in the hydrogenation material in the first stage was 120 ppm, and no hydrogen was added in the second stage.

[0190] The evaluation conditions of Comparative Example 4 were similar to those of Example 4, and the only difference was that the CO content was different, and the CO content in this comparative example was 1.1% (v / v).

[0191] Evaluation conditions:

[0192] Carbon di-material: acetylene 0.8% (v / v), ethylene 75% (v / v), ethane 23.5% (v / v), methane 0.3% (v / v), carbon tri 0.4% (v / v).

[0193] Crude hydrogen: hydrogen content 80% (v / v), methane content 18.9% (v / v), CO content 1.1% (v / v).

[0194] Process conditions: material space velocity 4500 / h, operating pressure 2.5 MPa, catalyst loading 100 mL

[0195] Two-stage hydrogenation process, first stage inlet temperature 90°C, hydrogen / acetylene 2.0; second stage inlet temperature 110°C,

[0196] CO content in hydrogenated material in first stage 220 ppm, no hydrogen in second stage.

[0197] Table 6 evaluation results

[0198]

[0199] From the evaluation results in Table 6, at the beginning of the reactor, under the conditions of CO content 120 ppm, hydrogen / acetylene 2, space velocity 4500 / h, the conversion rate of the first stage of Example is 81.0%, the actual acetylene removal amount is 0.645%, the hydrogen / acetylene at the first stage outlet is 5.92, which is much higher than that at the first stage inlet, indicating that the presence of CO improves the selectivity of the reaction, so that acetylene hydrogenation occurs at the same time, and the side reaction of ethylene hydrogenation is very small, so the second stage does not need to be hydrogenated. The acetylene content at the second stage outlet is less than 1 ppm, indicating that under the condition of obvious competitive adsorption effect between CO and acetylene, the catalyst has sufficient acetylene removal capacity and can completely convert acetylene.

[0200] After 1000 hours, the acetylene content at the first stage outlet increases, and the hydrogen / acetylene at the first stage outlet decreases, indicating that the selectivity of the first stage hydrogenation decreases, but the hydrogen / acetylene is still much higher than that at the first stage inlet, indicating that the catalyst performance is still good; the acetylene content at the second stage outlet is less than 3 ppm, indicating that the activity of the second stage is still good;

[0201] The evaluation conditions of Comparative Example 4 and Example 4 are the same except that the CO content of the hydrogen introduced into the hydrogenation material is different. The CO content of the material of Example 4 is 120 ppm and that of Comparative Example 4 is 220 ppm. From the results of the initial 24 hours of evaluation, the acetylene content at the outlet of the first stage of Comparative Example 4 is higher than that of Example 4 and the hydrogen / acetylene content at the outlet of the first stage is lower than that of Example 4, indicating that the high CO content inhibits the hydrogenation of the first stage. However, it is still much higher than the inlet of the first stage and is still conducive to the hydrogenation of the second stage. The acetylene content at the outlet of the second stage is 1.5 ppm, reaching the target requirement. Since the temperature at the inlet of the second stage is 110°C, which is the highest acceptable temperature, it indicates that the acetylene removal capacity of the catalyst under this condition has reached its maximum limit.

[0202] After 1000 hours, the acetylene content at the outlet of the first stage of Comparative Example 4 increases compared to the initial period and the outlet hydrogen / acetylene decreases to below 3.0, indicating that the performance of the catalyst in the first stage has decreased. The catalyst performance degradation rate is faster than that of Example 4, which may be due to the high CO content and the generation of more by-products. The acetylene content at the outlet of the second stage exceeds the standard, indicating that under the condition of high CO content, low hydrogen / acetylene also

[0203] After 1000 hours, the acetylene content at the outlet of the second stage of Comparative Example 4 reaches 0.015%, far exceeding the specified value, indicating that under this condition, the acetylene content at the inlet of the second stage exceeds its maximum acetylene removal capacity. The reason may be the competitive adsorption effect of CO on acetylene and the low hydrogen / acetylene, which causes the second stage reactor to fail to completely convert acetylene.

[0204] From the amount of coking generated, the coking amount of each stage of the catalysts of Example 4 and Comparative Example 4 does not exceed 10%, indicating that although the performance of the catalysts has decreased, there has been no serious decline. The coking amount of the first stage in Example 4 is higher than that of the second stage, indicating that the hydrogenation load of the first stage is higher than that of the second stage. However, in Comparative Example 4, the coking amount of the second stage is higher than that of the first stage, indicating that the load of the second stage is higher than that of the first stage. This may be due to the increased temperature, which intensifies the hydroformylation reaction of CO, generating more by-products.

[0205] Example 5

[0206] Carrier: A commercially available bimodal pore distribution spherical carrier with a diameter of 4 mm is used. The composition is 90% alumina and 10% magnesium oxide. It is calcined at 1150°C, with a specific surface area of 15.0 m 2 / g, a water absorption rate of 50%, a small pore size of 40-60 nm, and a large pore size of 350-600 nm. 100 g of the carrier is weighed.

[0207] Catalyst preparation:

[0208] (1) 0.315 g of silver nitrate was weighed into 50 g of deionized water, and then 100 g of the calcined carrier was added to the Ag salt solution. After the solution was completely absorbed, the mixture was aged for 2 h, dried at 60°C, and calcined at 450°C for 4 h to obtain the semi-finished catalyst P;

[0209] (2) 7.82 g of iron nitrate was weighed into 50 g of deionized water, and then the semi-finished catalyst P was added to the prepared Fe salt solution. After the solution was completely absorbed, the mixture was dried at 100°C and calcined at 400°C for 6 h to obtain the semi-finished catalyst Q;

[0210] (3) 11.66 mg of palladium chloride was weighed into 60 g of deionized water, and the pH was adjusted to 2.1. Then the semi-finished catalyst Q was added to the Pd salt solution, aged for 10 h, dried at 80°C, and calcined at 400°C for 4 h to obtain the semi-finished catalyst R;

[0211] (4) 11.05 g of nickel chloride was weighed into 45 ml of deionized water, and then 12.86 g of n-hexane, 1.54 g of CTAB, and 1.29 g of n-pentanol were added to form a microemulsion. The semi-finished catalyst R was immersed in the prepared microemulsion, and then the mixture was dried at 100°C and calcined at 450°C for 5 h to obtain the semi-finished catalyst S.

[0212] (5) 10.87 mg of palladium nitrate was weighed into 45 ml of deionized water, and then 12.86 g of n-hexane, 1.54 g of CTAB, and 1.29 g of n-pentanol were added to form a microemulsion. The semi-finished catalyst S was immersed in the prepared microemulsion, and then the mixture was dried at 100°C and calcined at 400°C for 4 h to obtain the desired catalyst.

[0213] The particle size of the microemulsion prepared in steps (4) and (5) was determined by dynamic light scattering to be 599.85 nm.

[0214] The prepared catalyst was determined by atomic absorption spectrometry, and the Pd content, Ni content, Fe content, and Ag content were 0.012%, 5.0%, 1.8%, and 0.2%, respectively, based on 100% of the carrier. Among them, the Pd content loaded by the solution method was 0.007%, and the Pd content loaded by the emulsion method was 0.005%.

[0215] Before use, it was placed in a fixed bed reaction device and reduced for 12 h at a temperature of 220°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0216] Comparative Example 5

[0217] Carrier: the same as in Example 5.

[0218] Catalyst: same as Example 5.

[0219] Before use, place in a fixed bed reactor and reduce at 220°C for 12 h using a mixture of N2:H2=1 :1.

[0220] Evaluation test

[0221] Evaluation conditions for Example 5:

[0222] Carbon two raw material: acetylene 1.3% (v / v), ethylene 80% (v / v), ethane 18.5% (v / v), methane 0.1% (v / v), carbon three 0.1% (v / v).

[0223] Crude hydrogen: hydrogen content 80% (v / v), methane content 19.2% (v / v), CO content 0.8% (v / v).

[0224] Process conditions: material space velocity 3500 / h, operating pressure 2.3 MPa, catalyst loading 100 mL

[0225] Three-stage hydrogenation process, first stage inlet temperature 70°C, second stage inlet temperature 85°C, third stage 110°C, first stage inlet hydrogen / acetylene 1.5;

[0226] CO content in hydrogenated material in the first stage 195 ppm, no hydrogen in the second and third stages.

[0227] Evaluation conditions for Comparative Example 5:

[0228] Carbon two raw material: acetylene 1.3% (v / v), ethylene 80% (v / v), ethane 18.5% (v / v), methane 0.1% (v / v), carbon three 0.1% (v / v).

[0229] Crude hydrogen: hydrogen content 80% (v / v), methane content 19.2% (v / v), CO content 0.8% (v / v).

[0230] Process conditions: material space velocity 3500 / h, operating pressure 2.3 MPa, catalyst loading 100 mL

[0231] Three-stage hydrogenation process, first stage inlet temperature 70°C, second stage inlet temperature 85°C, third stage 110°C, first stage inlet hydrogen / acetylene 1.2;

[0232] CO content in hydrogenated material in the first stage 156 ppm, no hydrogen in the second and third stages.

[0233] Evaluation results in Table 7

[0234]

[0235] From the evaluation results of Table 7, the hydrogen / acetylene of the outlet of the first section of Example 5 is 1.84, and the hydrogen / acetylene of the outlet of the second section is 5.79, that is, the hydrogen / acetylene is higher and higher towards the end, especially the hydrogen / acetylene of the outlet of the second section, which is much higher than 3, and the temperature of the third section is the highest, which is very favorable to the complete conversion of acetylene in the third section.

[0236] Compared with Example 5, the hydrogen / acetylene of the inlet of the first section of Comparative Example 5 is low, thus the introduced CO is less, and thus the acetylene conversion rate of the first section and the second section of Comparative Example 5 is higher than that of Example 5. The hydrogen / acetylene of the outlet of the first section and the second section of Comparative Example is 1.35 and 2.38 respectively, both of which are higher than the hydrogen / acetylene of the inlet of the first section, and also higher and higher, but since the hydrogen / acetylene of the outlet of the second section is less than 3, although the inlet temperature of the third section has reached 110℃, the catalyst cannot completely convert acetylene under the condition of reaching the highest activity due to the lack of hydrogen.

[0237] From the selectivity, the total selectivity of Comparative Example 5 reaches 86.9% after 1000 hours, which is higher than that of Example 5 without considering the conversion of acetylene, which is probably because the hydrogen amount of each section of Comparative Example 5 is less than that of each section of Example 5, thus the consumption of hydrogen is less, and thus the total selectivity is better. Since the CO content of Example 5 is higher, the selectivity is lower than that of Comparative Example 5, which indicates that when the hydrogen is too less, the factor affecting the consumption of hydrogen is not the CO content, but the hydrogen amount. But because the hydrogen of Comparative Example is too less, the hydrogen / acetylene of the inlet of the last section is less than the limit value, and acetylene cannot be completely converted.

[0238] From Table 7, it can also be seen that the CO content of the inlet of the first section of Example 5 and Comparative Example 5 is quite different, but the acetylene conversion rate of the first section is less different, thus an important conclusion can be drawn, that is, when Fe is the main active component, the hydrogenation activity is less sensitive to the CO content, which is an advantage for the hydrogenation reaction using crude hydrogen as the hydrogen source, that is, the change of the CO content will not cause a relatively sharp change of the activity of the catalyst, which is favorable for the stability of the reaction, and as long as the hydrogen of the inlet of the reactor is sufficient, the reactor at the end does not need to be hydrogenated, and thus acetylene can be completely converted stably, which is of great significance to the stable operation of the ethylene device.

[0239] Of course, the present application can also have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A method for selectively hydrogenating carbon di- fraction, the carbon di-fraction and hydrogen being subjected to selective hydrogenation in a hydrogenation reactor containing a catalyst, the process conditions of the selective hydrogenation being: reactor inlet temperature 55-110°C, reaction pressure 1.5-3.0 MPa, gas volume space velocity 1000-5000 h -1 ; characterized by: The hydrogen / acetylene volume ratio at the reactor inlet is 1.3~3.0, and the hydrogen is derived from crude hydrogen, which contains 0.1%-1% CO. The catalyst used in the selective hydrogenation reaction has an alumina or mainly alumina carrier with a specific surface area of 15-40 m 2 / g, a bimodal pore size distribution, a small pore size of 20-60 nm, and a large pore size of 70-600 nm; the active components include Pd, Ni and Fe, Pd is loaded by microemulsion method and solution method, Ni is loaded by microemulsion method, and Fe is loaded by solution method; and the solution method for loading Pd is after the solution method for loading Fe, and the microemulsion method for loading Pd is after the microemulsion method for loading Ni; the Pd and Ni loaded by the microemulsion method are located in the large pores, and the Fe and Pd loaded by the solution method are located in the small pores; Based on the mass of the carrier (100%), the Ni content is 1.0%–5%, the Fe content is 1%–2.5%, and the Pd content is 0.007%–0.018%; wherein, the Pd content loaded by solution method is 0.005%–0.01%, and the Pd content loaded by microemulsion method is 0.002%–0.008%. The catalyst is reduced at 180–230 °C before being used in the selective hydrogenation reaction.

2. The process for the selective hydrogenation of carbon di- fraction according to claim 1, characterized in that, The C2 fraction comes from the top of the pre-deethaner column, and based on the total volume of the C2 fraction as 100%, it includes 60% to 90% ethylene and 0.1% to 1.5% acetylene.

3. The process for the selective hydrogenation of carbon di- fraction according to claim 1, characterized in that, The hydrogenation reactor is a fixed-bed hydrogenation reactor, which is an adiabatic or isothermal reactor.

4. The process for the selective hydrogenation of carbon di- fraction according to claim 1, characterized in that, The selective hydrogenation reaction can be a single-stage hydrogenation, a two-stage hydrogenation, or a three-stage hydrogenation; in a two-stage hydrogenation reaction, no hydrogen is added in the second stage; in a three-stage hydrogenation reaction, no hydrogen is added in the third stage or a small amount of hydrogen is added.

5. The process for the selective hydrogenation of carbon di- fraction according to claim 1, characterized in that, The process of loading Ni or Pd using the microemulsion method includes the following steps: dissolving the precursor salt of Ni or the precursor salt of Pd in ​​water to obtain an aqueous phase, and then adding an oil phase, a surfactant, and a co-surfactant to the aqueous phase and stirring to form a microemulsion.

6. The process for the selective hydrogenation of carbon di- fraction according to claim 5, characterized in that, The mass ratio of the aqueous phase to the oil phase is 2.2 to 3.5, the mass ratio of the surfactant to the oil phase is 0.12 to 0.55, and the mass ratio of the surfactant to the co-surfactant is 1.0 to 1.

3.

7. The selective hydrogenation method for C2 fraction as described in claim 5, characterized in that, The oil phase is a C6-C8 saturated alkane or cycloalkane; The surfactant is an ionic surfactant and / or a nonionic surfactant; The co-surfactant is an organic alcohol.

8. The selective hydrogenation method for C2 fraction as described in claim 1, characterized in that, The order of loading the active component into the carrier includes the following steps: Ni loaded using microemulsion method, Fe loaded using solution method, Pd loaded using solution method, and Pd loaded using microemulsion method; or Ni loaded using microemulsion method, Fe loaded using solution method, Pd loaded using microemulsion method, Pd loaded using solution method; or Solution-loaded Fe, solution-loaded Pd, microemulsion-loaded Ni, microemulsion-loaded Pd; or Ni loaded by microemulsion method, Pd loaded by microemulsion method, Fe loaded by solution method, and Pd loaded by solution method.

9. The selective hydrogenation method for C2 fraction as described in claim 1, characterized in that, The active component in the catalyst also includes Ag, which is supported by a solution method.

10. The selective hydrogenation method for C2 fraction as described in claim 9, characterized in that, The Ag content is 0.1% to 0.3% based on the mass of the carrier (100%).

11. The selective hydrogenation method for C2 fraction as described in claim 7, characterized in that, The oil phase is cyclohexane or n-hexane.

12. The selective hydrogenation method for C2 fraction as described in claim 7, characterized in that, The surfactant is a nonionic surfactant.

13. The selective hydrogenation method for C2 fraction as described in claim 7, characterized in that, The surfactant is polyethylene glycol octylphenyl ether or hexadecyltrimethylammonium bromide.

14. The selective hydrogenation method for C2 fraction as described in claim 7, characterized in that, The organic alcohol is selected from C4 to C6 alcohols.

15. The selective hydrogenation method for C2 fraction as described in claim 14, characterized in that, The organic alcohol is selected from n-butanol and / or n-pentanol.

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