Selective hydrogenation method for C2 fraction

Abstract

The invention provides a C2 fraction selection method, which comprises the following reaction process conditions: the reactor inlet temperature is 55-110 DEG C, the reaction pressure is 1.5-3.0 MPa, the gas volume space velocity is 1000-5000h <-1 >, the reactor inlet hydrogen is from crude hydrogen, the CO content in the crude hydrogen is 0.1-1%, the hydrogen / alkyne volume ratio is 1.3-3.0, and the gas volume space velocity is 1-5,000 h <-1 >. The catalyst used in the hydrogenation method adopts non-noble metal Fe as a main active component, through the combination of the catalyst and 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 selective hydrogenation efficiency of C2 hydrogenation fractions is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogenation, and in particular relates to a method for selective hydrogenation of carbon distillation. Background Art

[0002] Polymerization-grade ethylene production is the leader of the petrochemical industry, and polymerization-grade ethylene is the most basic raw material for downstream polymerization units. Among them, the selective hydrogenation of acetylene has an extremely important impact on the ethylene processing 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 unit.

[0003] The cracked carbon distillate contains acetylene. When producing polyethylene, a small amount of acetylene in ethylene will reduce the activity of the polymerization catalyst and deteriorate the physical properties of the polymer. Therefore, the acetylene content in ethylene must be reduced to a certain limit before it can be used as a monomer for synthesizing polymers. Therefore, acetylene separation and conversion is one of the important processes in the ethylene plant process.

[0004] Catalytic selective hydrogenation in ethylene units includes pre-hydrogenation and post-hydrogenation. Pre-hydrogenation and post-hydrogenation of acetylene 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 advantages of the post-hydrogenation process are that there are many control methods for the hydrogenation process, it is not easy to overheat, and it is easy to operate, but the disadvantages are that the catalyst is easy to coke and the catalyst regeneration is relatively frequent. The reason is that in the hydrogenation process, due to the small amount of hydrogen added, the hydrogenation dimerization reaction of acetylene is easy to occur, generating 1,3-butadiene, and further generating oligomers with a wide molecular weight, commonly known as "green oil". Green oil is adsorbed on the catalyst surface and further forms coke, blocking the catalyst pores, and reducing the catalyst activity and selectivity. Therefore, in the carbon two 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] In view of this problem, Chinese patent document CN112679301B discloses a method for selective hydrogenation of carbon distillation fractions, wherein the hydrogenation raw material comes from a deethanizer, and the hydrogen added is crude hydrogen. In the preparation of the catalyst, a W / O type microemulsion having a particle size larger than the pores of the carrier is adopted, and the metal salts of nickel, copper and palladium are contained in the microemulsion. Since the kinetic volume of the microemulsion is larger than the pore size, the microemulsion particles can only enter the macropores of the carrier. Part of the Pd is loaded by a solution method, and due to the siphon effect of the pores, this part of the Pd is located in the 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, the microemulsion method is adopted to load part of the Pd outside the Ni-Cu active center. But the reduction temperature of Ni-Cu often reaches about 350 ℃, at which the Pd atoms in the reduced state are easily aggregated, which greatly reduces the catalyst activity. 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 its reduction temperature can be reduced to 150 ℃. Since palladium is loaded twice, the content of palladium in the catalyst is therefore higher than that of commonly used catalysts, which is more than 50% higher at most, which greatly increases the catalyst cost and makes the catalyst preparation process more complicated. In addition, since palladium needs to be loaded by 2 different methods, when the microemulsion method is loaded with palladium, it is necessary to adopt the microemulsion substantially the same as that of nickel-copper loading, 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 precious metal Pd, its loading capacity is relatively large, causing the catalyst cost to remain high.

[0006] Chinese patent document CN1129606A discloses a hydrocarbon conversion catalyst and preparation method, wherein the carrier catalyst includes aluminum oxide, nickel oxide, iron oxide, etc., and the catalyst includes two kinds of holes, one for improving the catalytic reaction surface and the other for diffusion. CN101433842A discloses a hydrogenation catalyst, wherein the catalyst has a bimodal pore distribution, the most probable radius of the small pore part is 2-50nm, and the most probable radius of the large pore part is 100-400nm. 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 a macroporous structure can improve the selectivity, the larger molecules generated by polymerization and chain growth reactions are also easily accumulated in the carrier macropores, causing the catalyst to coke and deactivate, affecting the service life of the catalyst.

[0007] Chinese patent document CN104098425A discloses a method for selecting carbon distillation fractions. A catalyst is used in the hydrogenation method, and its active components Pd and Ag are loaded by aqueous solution impregnation method, and Ni is loaded by W / O microemulsion impregnation method. After adopting this method, Pd / Ag and Ni are located in pores of different pore sizes, and the green oil generated by the reaction is saturated with hydrogen in the macropores, 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 precious metal catalysts is low, but the reduction temperature of Ni often reaches about 500°C. At this temperature, the reduced Pd atoms are very easy to aggregate, which reduces the catalyst activity by more than 30%. It is necessary to significantly increase the amount of active components to compensate for the activity loss, but it will cause a decrease in selectivity.

[0008] If the hydrogenation feedstock contains CO, the hydrogenation process will have a hydrogenation acylation reaction, which will generate aldehydes, ketones, acids, etc. These fractions are more easily adsorbed on the alumina carrier, which will accelerate the process of green oil forming coke. However, in the above-disclosed catalysts, the main active component is Pd, and the by-product hydrogenation is mainly Ni. These components do not have the effect of carbonyl hydrogenation, that is, they cannot effectively reduce the coking rate of carbon two hydrogenation catalysts with CO. Since CO is introduced into the hydrogenation process, CO is a temporary poison of Pd, which will reduce its hydrogenation activity, and it is even more necessary to increase the content of the precious metal Pd, making the catalyst cost more expensive. Summary of the invention

[0009] The object of the present invention is to provide a method for selective hydrogenation of a carbon two fraction, using a catalyst with non-precious metal Fe as the main active component, reducing the sensitivity of the reaction temperature to the CO content during the hydrogenation process, and reducing the catalyst cost and the amount of catalyst coking while ensuring the selective hydrogenation efficiency of the carbon two hydrogenation fraction.

[0010] To achieve the above object, the present invention adopts the following technical solution:

[0011] A method for selective hydrogenation of carbon distillate, wherein the carbon distillate and hydrogen are selectively hydrogenated in a hydrogenation reactor containing a catalyst, wherein the process conditions of the selective hydrogenation reaction are: reactor inlet temperature 55-110°C, reaction pressure 1.5-3.0 MPa, gas volume space velocity 1000-5000 h -1 The reactor inlet hydrogen / alkyne volume ratio is 1.3 to 3.0, the hydrogen comes from crude hydrogen, and the CO content in the crude hydrogen is 0.1%-1%,

[0012] The catalyst used in the selective hydrogenation reaction is alumina or mainly alumina, with a specific surface area of ​​15 to 40 m 2 / g, having a bimodal pore size distribution characteristic, with a small pore size of 20-60nm and a large pore size of 70-600nm; the active components include Pd, Ni and Fe, Pd is loaded by both microemulsion method and solution method, Ni is loaded by microemulsion method, and Fe is loaded by solution method; and the solution method loads Pd after the solution method loads Fe, and the microemulsion method loads Pd after the microemulsion method loads Ni; the microemulsion method loads Pd and Ni in the large pores, and the solution method loads Fe and Pd in ​​the small pores;

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

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

[0015] In the selective hydrogenation method provided by the present invention, Fe in the catalyst is the main active component of the selective hydrogenation. During the hydrogenation process, CO in the crude hydrogen will also participate in the reaction, mainly undergoing formylation reaction with hydrogen and olefins to generate carbonyl-containing compounds. The adsorption strength of these carbonyl-containing compounds on alumina is higher than that of olefins, and they stay on the catalyst for a longer time, resulting in a decrease in the hydrogenation activity of Fe.

[0016] Moreover, the catalyst needs to be reduced before the hydrogenation reaction. Both Pd and Ni components need to be reduced from an oxidized state to a metallic state under the action of hydrogen. The reduction temperature of Pd oxide is no higher than 150°C, and the reduction temperature of Ni oxide is 350-400°C. This temperature is too high for Pd, which can easily cause the aggregation of active centers and form larger active centers, thereby reducing the activity selectivity of the hydrogenation reaction.

[0017] Therefore, in this hydrogenation process, two key issues need to be addressed: 1) the hydrogenation activity of Fe; 2) the growth of Pd particles caused by the reduction temperature of 350-400°C.

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

[0019] In the above hydrogenation method provided by the present invention, non-precious metal iron is used as the main active component, and a catalyst having a carrier with a bimodal pore size distribution (large pores loaded with Ni and a small amount of Pd, small pores loaded with Fe and a small amount of Pd) is used. In addition to acetylene, ethylene and ethane, the hydrogenation material also contains hydrogen, methane and CO from crude hydrogen. In the hydrogenation process, the selective hydrogenation of acetylene mainly occurs in the small pores loaded with Fe and a small amount of Pd. The by-products (such as butadiene and its derivative green oil, etc.) generated in the hydrogenation reaction are easier to enter the large pores of the catalyst due to their larger volume. Under the action of the Ni active center, the double bonds of the green oil fraction are saturated and hydrogenated to become alkanes, and no polymerization reaction occurs, thereby greatly reducing the rate of coking.

[0020] Optionally, in the above-mentioned C2 fraction selective hydrogenation method provided by the present invention, the C2 fraction comes from the top of the previous deethanizer, and based on the total volume of the C2 fraction as 100%, the ethylene content is 60% to 90%, and the acetylene content is 0.1% to 1.5%.

[0021] Optionally, in the above-mentioned method for selective hydrogenation of carbon two fractions provided by the present invention, the hydrogenation reactor is a fixed bed hydrogenation reactor, and the fixed bed reactor is an adiabatic or isothermal reactor.

[0022] Optionally, in the above-mentioned carbon two fraction selective hydrogenation method provided by the present invention, the selective hydrogenation reaction is single-stage hydrogenation, two-stage hydrogenation or three-stage hydrogenation; in two-stage hydrogenation, the second stage is not hydrogenated; in three-stage hydrogenation, the third stage is not hydrogenated or is hydrogenated in small amounts.

[0023] Optionally, in the above-mentioned carbon two fraction selective hydrogenation method provided by the present invention, microemulsion loading refers to traditional impregnation loading, and its impregnation liquid is a microemulsion; solution loading refers to traditional impregnation loading, and its impregnation liquid is a solution. The process of loading Ni by microemulsion or loading Pd by microemulsion recommended by the present invention comprises the following steps: dissolving a precursor salt of Ni or a 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.

[0024] Optionally, in the above-mentioned method for selective hydrogenation of carbon two fractions provided by the present invention, the particle size of the microemulsion is not less than the maximum pore size of the small pores of the carrier and not greater than the maximum pore size of the large pores, for example, the particle size of the microemulsion is 60 to 600 nm. For a specific catalyst carrier with a bimodal pore size distribution, the pore size of its small pores and the pore size of its large pores are respectively a size range, and the particle size of the microemulsion is not less than the maximum pore size of the small pores and not greater than the maximum pore size of the large pores means that the particle size of the microemulsion prepared during loading is not less than the upper limit of the pore size range of the small pores of a specific catalyst carrier and not greater 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 larger than the pore size of the small pores but smaller than the maximum pore size of the large pores. Due to spatial resistance, these components can only enter the large pores, so active centers with different hydrogenation effects are formed in the large and small pores of the catalyst. The large pores contain active centers composed of Ni, which have a good hydrogenation saturation effect on the green oil molecules, so that the green oil molecules entering the large pores will no longer polymerize, so they will gradually move out of the reactor and are not easy to form coke.

[0026] In the process of loading Ni or Pd by the microemulsion method recommended by the present invention, the mass ratio of the water 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.

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

[0028] The surfactant is an ionic surfactant and / or a nonionic surfactant, preferably a nonionic surfactant, more preferably polyethylene glycol octylphenyl ether or hexadecyltrimethylammonium bromide;

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

[0030] Optionally, in the method for selective hydrogenation of carbon two fractions provided by the present invention, the sequence of loading the active component into the carrier comprises the following steps:

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

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

[0033] Solution method loading Fe, solution method loading Pd, microemulsion loading Ni, microemulsion loading Pd; or

[0034] Microemulsion loading of Ni, microemulsion method loading of Pd, solution method loading of Fe, solution method loading of Pd.

[0035] Specifically, in the above-mentioned method for selective hydrogenation of carbon two fractions provided by the present invention, the preparation of the catalyst comprises the following steps:

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

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

[0038] (3) dissolving the precursor salt of Pd in ​​water, the volume of the solution being equal to the water absorption capacity of the carrier, adjusting the pH to 1.2-2.7, and then adding the semi-finished catalyst B to the Pd salt solution. After the solution is completely absorbed, drying and calcining at 400-550° C. to obtain the 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 stirring thoroughly to form a microemulsion; the conditions for preparing the microemulsion are: a weight ratio of surfactant / co-surfactant is 1 to 1.3, a weight ratio of water phase / oil phase is 2.2 to 3.5, and a weight ratio of surfactant / oil phase is 0.12 to 0.55; adding the semi-finished catalyst C to the prepared microemulsion and impregnating it, and after the solution is completely absorbed, drying it, and calcining it at 400 to 550° C. to obtain the desired catalyst of the semi-finished catalyst;

[0040] Among them, 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, in the above-mentioned carbon distillation selective hydrogenation method provided by the present invention, the active component in the catalyst also includes Ag, and the Ag is loaded by a solution method. Studies have found that Ag can improve the selectivity of the hydrogenation process and can also improve the ability of the catalyst bed to resist acetylene penetration when the acetylene content suddenly increases.

[0042] Optionally, in the above-mentioned carbon distillation selective hydrogenation method provided by the present invention, based on the mass of the carrier being 100%, the Ag content is 0.1% to 0.3%.

[0043] Specifically, the catalyst preparation method recommended by the present invention comprises the following steps:

[0044] (1) dissolving the Ni precursor salt in water, adding an oil phase, a surfactant and a co-surfactant, and stirring thoroughly to form a microemulsion, wherein the particle size of the microemulsion is controlled to be between 60 nm and 600 nm (including 60 and 600 nm); adding a carrier to the prepared microemulsion and immersing it for 0.5 to 4 hours, after the emulsion is completely absorbed and dried, calcining at 400 to 600° C. to obtain a semi-finished catalyst A;

[0045] (2) dissolving the Fe precursor salt in water, the amount of the solution being equal to the water absorption capacity of the carrier, adjusting the pH to , and then adding the semi-finished catalyst A to the Fe salt solution, aging, drying, and calcining at 250-600° C. after the solution is completely absorbed, to obtain the semi-finished catalyst B;

[0046] (3) The precursor salt of Pd is dissolved in water, the amount of the solution is equivalent to the water absorption capacity of the carrier, the pH is adjusted to 1.5-2.5, and then the semi-finished catalyst B is added to the Pd salt solution, shaken for 0.5-2 hours, dried and calcined at 400-550° C. to obtain the semi-finished catalyst C;

[0047] (4) dissolving the Pd precursor salt in water, adding the oil phase, the surfactant and the co-surfactant, and stirring thoroughly to form a microemulsion, wherein the particle size of the microemulsion is controlled to be greater than 60 nm and less than 600 nm; adding the semi-finished catalyst C to the prepared microemulsion for impregnation, and after the emulsion is completely dried by absorption, calcining at 400-550° C. to obtain the semi-finished catalyst D;

[0048] (5) Dissolve the Ag precursor salt in water, the amount of the solution being equivalent to the water absorption capacity of the carrier, then add the semi-finished catalyst D into the Ag salt solution, and after the solution is completely absorbed, age, dry, and calcine at 400-550° 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); step (5) the loading process can be performed in any order.

[0050] In each of the above steps, the precursor salt of the metal is a soluble salt, which may be its nitrate, chloride or other soluble salt. For example, the precursor salt of Pd may be selected from any soluble palladium salt such as palladium chloride and palladium nitrate; the precursor salt of Ni may be selected from any soluble nickel salt such as nickel chloride and nickel nitrate; the precursor salt of Fe may be selected from any soluble iron salt such as ferric nitrate and ferric chloride.

[0051] The beneficial effects of the present invention are as follows:

[0052] The selective hydrogenation method of carbon distillate provided by the present invention has good hydrogenation selectivity and long-cycle operation characteristics, which not only reduces the catalyst preparation cost, but also improves the target product yield and greatly reduces the rate of coking. Specifically, the main active component in the catalyst used adopts non-precious metal Fe, reduces the content of Pd, reduces the catalyst cost, and makes the catalyst easier to produce and replace. As the main active component, Fe has a lower adsorption intensity for CO than the main active component Pd of the traditional catalyst, which reduces the sensitivity of the reaction temperature to the CO content during the hydrogenation process, which is beneficial to the stability of the acetylene removal reaction. Moreover, since the catalyst cost is greatly reduced, the reaction can be operated at a lower space velocity to ensure that the reaction result is qualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a particle size distribution diagram of the microemulsion prepared in step (3) of Example 2 of the present invention. DETAILED DESCRIPTION

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

[0055] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0056] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

[0057] Analytical test methods:

[0058] Ratio measurement, GB / T-5816; Instrument: TristarII3020,

[0059] Metal content measurement, SH / T 0694-1999; Instrument: AA240FS, determination of Pd, Ag, Ni, Fe content in 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 (%) = [(acetylene content at reactor inlet - acetylene content at reactor outlet) / acetylene content at reactor inlet] × 100%

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

[0065] The initial conversion rate refers to the acetylene conversion rate within 24 hours after the reactor is charged.

[0066] Coking amount = [(catalyst weight after reaction - catalyst weight before reaction) / reactor catalyst weight] × 100% Agilent 7890A gas chromatograph was used to measure the hydrogen and acetylene contents at the reactor outlet and inlet.

[0067] Raw materials: nickel nitrate, palladium nitrate, ferric nitrate, nickel chloride, ferric chloride, palladium chloride, n-hexane, cyclohexane, CTAB, Triton X-100, n-butanol, n-octanol, n-pentanol, analytical grade, all purchased from Shanghai Sinopharm Group Co., Ltd.; alumina carrier was purchased from Shandong Aluminum Industry Group Co., Ltd.

[0068] The present invention is further described below by way of examples, but it is not intended that the present invention is limited thereto.

[0069] Example 1

[0070] Carrier: Weigh a commercially available bimodal pore distribution spherical carrier with an alumina content of 90%, a titanium oxide content of 10%, and a diameter of 4 mm. After calcination at 1100°C for 4 hours, the pore size distribution ranges are 30-50 nm and 200-450 nm, respectively, the water absorption rate is 65%, and the specific surface area is 30.18 m 2 / g, weigh 100g of the carrier.

[0071] Catalyst preparation:

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

[0073] (2) Weigh 13.33 mg of palladium chloride and dissolve it in 55 ml of deionized water, add 19.6 g of cyclohexane, 5.89 g of Triton X-10, and 4.53 g of n-pentanol, stir well to form a microemulsion, and immerse the semi-finished catalyst A in the prepared microemulsion. After the emulsion is completely absorbed, dry it at 60° C. and calcine it at 550° C. for 6 hours to obtain the semi-finished catalyst B;

[0074] (3) Weigh 7.27 g of ferric chloride and dissolve it in 65 g of deionized water, then add the semi-finished catalyst B to the prepared Fe salt solution. After the solution is completely absorbed, dry it at 100° C. and calcine it at 250° C. for 8 hours to obtain the semi-finished catalyst C;

[0075] (4) Weigh 16.67 mg of palladium chloride and dissolve it in 65 g of deionized water. Adjust the pH to 1.2. Then add the semi-finished catalyst C to the prepared Pd salt solution, age it for 4 hours, dry it at 120°C, and calcine it at 450°C for 6 hours. Then, the desired catalyst is obtained.

[0076] The particle sizes of the microemulsions prepared in step (1) and step (2) were both 299.87 nm as determined by dynamic light scattering.

[0077] According to the atomic absorption spectrometry, based on the mass of the carrier as 100%, the Pd content of the catalyst is 0.018%, the Ni content is 4%, and the Fe content is 2.5%. The Pd content of the solution method is 0.01%, and the Pd content of the emulsion method is 0.008%.

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

[0079] Comparative Example 1

[0080] Carrier: Same as Example 1.

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

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

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

[0084] (3) Weigh 16.67 mg of palladium chloride and dissolve it 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. Aged for 4 hours, dried at 120°C, and calcined at 450°C for 6 hours. The desired catalyst is obtained.

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

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

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

[0088] Evaluation experiment

[0089] Condition 1

[0090] C2 raw materials: acetylene 0.1% (v / v), ethylene 60% (v / v), ethane 39% (v / v), methane 0.2% (v / v), C3 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 2.2MPa, reactor inlet temperature 55°C, hydrogen / alkyne 3.0, CO content in hydrogenated material 50ppm.

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

[0094] Table 1 Reaction results of condition 1

[0095]

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

[0097] Condition 2

[0098] C2 raw materials: acetylene 0.3% (v / v), ethylene 70% (v / v), ethane 29% (v / v), methane 0.3% (v / v), C3 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 1.5MPa, hydrogen / alkyne 2.5, catalyst loading 150mL, CO content in hydrogenated material 82ppm. Reaction results are shown in Table 2 Table 2 Reaction results of working condition 2

[0101]

[0102] As can be seen from Table 2, in operating condition 2, as the acetylene content increases to 0.3%, the CO content in the material also increases to 52.5ppm. During the 1000-hour evaluation process, the acetylene content at the reactor outlet of Example 1 was always less than 1ppm. The comparative example was close to unqualified at 500 hours. After 2000 hours, the catalyst coking of Comparative Example 1 was close to 9%, and the catalyst coking of Example 1 also increased significantly relative to operating condition 1, indicating that as the acetylene content and CO content increase, the amount of by-products generated also increases. Relative to operating condition 1, the selectivity of the embodiment and comparative example 1 is improved, indicating that the increase in the CO content in the material can improve the selectivity of the reaction, but the amount of coking increases relatively. The deactivation rate of the catalyst is accelerated. However, there is no Ni loaded in Comparative Example 1, 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] Carrier: Weigh a commercially available bimodal pore distribution spherical carrier, with an alumina content of 95%, a titanium oxide content of 5%, and a diameter of 4 mm. After calcination at 1120°C for 4 hours, the pore size distribution ranges are 35-55 nm and 300-500 nm, respectively, the water absorption rate is 55%, and the specific surface area is 20.38 m 2 / g, weigh 100g of the carrier.

[0105] Catalyst preparation:

[0106] (1) Weigh 6.52 g of ferric nitrate and dissolve it in 55 g of deionized water. Then add the calcined carrier to the prepared Fe salt solution. After the solution is completely absorbed, dry it at 120°C and calcine it at 300°C for 6 hours to obtain a semi-finished catalyst D.

[0107] (2) Weigh 13.33 mg of palladium chloride and dissolve it in 55 g of deionized water, adjust the pH to 1.6, then add the semi-finished catalyst D to the prepared Pd salt solution, and after the solution is completely absorbed, age it for 10 hours, dry it at 100°C, and calcine it at 500°C for 6 hours to obtain the semi-finished catalyst E.

[0108] (3) Weigh 9.38 g of nickel nitrate, dissolve it in 48 ml of deionized water, add 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol, stir well to form a microemulsion, and impregnate the semi-finished catalyst E into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 80° C. and calcine it at 400° C. for 5 h to obtain the semi-finished catalyst F.

[0109] (4) Weigh 6.67 mg of palladium chloride and dissolve it in 48 ml of deionized water. Add 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol. Stir thoroughly to form a microemulsion. Impregnate the semi-finished catalyst F into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 60°C and calcine it at 400°C for 6 hours to obtain the desired catalyst.

[0110] The particle size of the microemulsion prepared in steps (3) and (4) was 200.15 nm as determined by dynamic light scattering. Specifically, Figure 1 This is the particle size distribution diagram of the microemulsion prepared in step (3) of this embodiment, 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 particle sizes of 185 and 215 nm is lower 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 measured by atomic absorption spectrometry, and the Pd content was 0.012%, the Ni content was 3%, and the Fe content was 1.5%, with the carrier as 100%. The Pd content of the solution method was 0.008%, and the Pd content of the emulsion method was 0.004%.

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

[0113] Comparative Example 2

[0114] Carrier: Same as Example 2.

[0115] Catalyst preparation: Similar to Example 2, except that no Fe is loaded in Comparative Example 2. Catalyst preparation:

[0116] (1) 13.33 mg of palladium chloride was weighed and dissolved in 55 g of deionized water, and the pH was adjusted to 1.6. Then 100 g of the calcined support was added to the prepared Pd salt solution. After the solution was completely absorbed, the solution 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) Weigh 9.38 g of nickel nitrate, dissolve it in 48 ml of deionized water, add 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol, stir well to form a microemulsion, and impregnate the semi-finished catalyst E1 into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 80° C. and calcine it at 400° C. for 5 h to obtain the semi-finished catalyst F1;

[0118] (3) Weigh 6.67 mg of palladium chloride and dissolve it in 48 ml of deionized water. Add 19.2 g of cyclohexane, 6.72 g of Triton X-100, and 5.6 g of n-hexanol. Stir thoroughly to form a microemulsion. Impregnate the semi-finished catalyst F1 into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 60°C and calcine it 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 200.18 nm as measured by dynamic light scattering.

[0120] The prepared catalyst was measured by atomic absorption spectrometry, and the Pd content was 0.012% and the Ni content was 3% based on the carrier as 100%, wherein the Pd content of the solution method was 0.008% and the Pd content of the emulsion method was 0.004%.

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

[0122] Evaluation test

[0123] C2 raw materials: acetylene 0.6% (v / v), ethylene 85% (v / v), ethane 13.5% (v / v), methane 0.2% (v / v), C3 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 2.0MPa, reactor inlet temperature 65°C for the first reactor, hydrogen / alkyne 1.8, second reactor inlet temperature 110°C, CO content in hydrogenated material 148ppm, catalyst loading 100mL. The reaction results are shown in Tables 3 and 4.

[0126] Table 3 Reaction results

[0127]

[0128] Table 4 1500 hours coking amount

[0129]

[0130]

[0131] From Table 3, it is known that the acetylene content at the outlet of the first and second stage reactors in Comparative Example 2 is much higher than that in Example 2, indicating that in the absence of Fe loading, the catalyst's acetylene removal activity is very poor, indicating that Fe is the main active component of acetylene hydrogenation; the hydrogenation activity of the second stage reactor in the comparative example is higher than that of the first stage, and the reason may be that the reactor inlet temperature of the second stage is much higher than that of the first stage, and a small amount of Pd loaded is called the active component of acetylene hydrogenation, but the loading amount is too small and its activity is insufficient. From Example 2, when the CO content reaches 148ppm, the acetylene conversion rate of the first stage also reaches more than 70%, and the hydrogen / alkyne at the outlet of the first stage is higher than the hydrogen / alkyne at the inlet of the first stage, indicating that the selectivity of the first stage is excellent; because the hydrogen / alkyne increases after the first stage reaction, the second stage does not need to be equipped with hydrogen, and at the outlet of the second stage reactor, there is still a relatively high amount of hydrogen remaining, indicating that in the presence of higher CO, even if the inlet temperature of the second stage reactor is as high as 110°C, hydrogen does not over-hydrogenate with ethylene, and after 1500 hours, the total selectivity still reaches 81.7%, indicating that under this operating condition, the catalyst has good selectivity. From 24 hours to 1500 hours later, the acetylene content at the second-stage outlet of Example 2 was less than 1 ppm, indicating that the catalyst had good acetylene removal activity in the presence of CO.

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

[0133] Example 3

[0134] Catalyst preparation:

[0135] The commercially available bimodal pore distribution spherical alumina carrier has a diameter of 4 mm. After calcination at 1060°C for 4 hours, the pore size distribution ranges are 20-40 nm and 70-150 nm, respectively, the water absorption rate is 70%, and the specific surface area is 39.85 m 2 / g, weigh 100g of the carrier.

[0136] (1) 3.13 g of nickel nitrate was weighed and dissolved in 60 ml of deionized water, and 27.28 g of n-hexane, 15 g of Triton X-100, and 15 g of n-butanol were added and stirred to form a microemulsion. 100 g of the carrier was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, it was dried at 60° C. and calcined at 600° C. for 5 h to obtain a semi-finished catalyst G;

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

[0138] (3) 8.33 mg of palladium chloride was weighed and dissolved in 70 g of deionized water, and the pH was adjusted to 1.7. The semi-finished catalyst H was then added to the Pd salt solution, aged for 18 hours, dried at 100° C., and calcined at 520° C. for 4 hours to obtain a 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 ml of n-butanol, stir thoroughly to form a microemulsion, and impregnate the semi-finished catalyst I into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 60° C. and calcine it at 550° C. for 4 hours to obtain a semi-finished catalyst J;

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

[0141] The particle size of the microemulsion prepared in steps (1) and (4) was 60.23 nm as measured by dynamic light scattering.

[0142] The prepared catalyst was measured by atomic absorption spectrometry. Calculated based on the carrier as 100%, the Pd content was 0.007%, the Ni content was 1%, the Fe content was 1%, and the Ag content was 0.3%. 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 with a mixed gas with a molar ratio of N2:H2=1:1 at 230°C for 8 hours.

[0144] Comparative Example 3

[0145] Carrier: Same as Example 3.

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

[0147] Catalyst preparation:

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

[0149] (2) Weigh 4.35 g of ferric nitrate and dissolve it in 70 g of deionized water, then add the semi-finished catalyst G into the Fe salt solution, and after the solution is completely absorbed, dry it at 120° C. and calcine it at 600° C. for 4 hours to obtain the semi-finished catalyst H;

[0150] (3) 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 well to form a microemulsion, and impregnate the semi-finished catalyst I into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 60° C. and calcine it at 550° C. for 4 hours to obtain the semi-finished catalyst I;

[0151] (4) Weigh 0.47 g of silver nitrate and dissolve it in 70 g of deionized water. Then add the semi-finished catalyst J to the Fe salt solution. After the solution is completely absorbed, age it for 2 hours, dry it at 120° C., and calcine it at 500° C. for 4 hours to obtain the desired catalyst.

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

[0153] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support being 100%, the Pd content of the catalyst was 0.002%, the Ni content was 1%, the Fe content was 1%, and the Ag content was 0.3%.

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

[0155] Evaluation test

[0156] Working conditions

[0157] C2 raw materials: acetylene 1.5% (v / v), ethylene 90% (v / v), ethane 8% (v / v), methane 0.2% (v / v), C3 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 hydrogenation material is 20ppm;

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

[0161] Three-stage hydrogenation process, the first stage inlet temperature is 55°C, hydrogen / alkyne 1.3; the second stage inlet temperature is 65°C, and the third stage inlet temperature is 90°C. No hydrogen is added in 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, it can be seen that in the initial stage of the reaction of Example 3, the hydrogen / alkyne at the outlet of the first stage reactor and the outlet of the second stage reactor are 1.54 and 3.13 respectively, which are both higher than the hydrogen / alkyne at the inlet of the first stage reactor, indicating that in the overall bed layer, the higher the hydrogen / alkyne is, and the higher the temperature of the bed layer is, the more conducive it is to convert acetylene. As long as the catalyst activity is sufficient, all acetylene can be converted. In other words, as long as the hydrogen / alkyne at the inlet of the first stage and the temperature of each stage are within the appropriate range, the second and third stage reactors of the hydrogenation process do not need to be equipped with hydrogen.

[0165] From the initial stage of the reaction to 1500 hours, the acetylene at the three-stage outlet was always qualified. After 1500 hours, the total selectivity could still reach a high value of 84.0%.

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

[0167] Although a large amount of acetylene still remains 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 embodiment, indicating that the addition of Pd does not affect the selectivity of hydrogenation.

[0168] Example 4

[0169] Carrier: A commercially available bimodal pore distribution spherical alumina carrier with a diameter of 3 mm was used. After calcination at 1100°C for 4 hours, the bimodal pore size distribution range was 25-45 nm and 100-220 nm, the water absorption rate was 65%, and the specific surface area was 35.34 m 2 Weigh 100 g of the carrier.

[0170] Catalyst preparation:

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

[0172] (2) Weigh 10 mg of palladium chloride and dissolve it in 60 ml of deionized water, add 26.08 g of cyclohexane, 13.04 g of Triton X-100, and 11.86 g of n-butanol, stir well to form a microemulsion, and immerse the semi-finished catalyst K in the prepared microemulsion. After the emulsion is completely absorbed, dry it at 100° C. and calcine it at 550° C. for 6 hours to obtain a semi-finished catalyst M;

[0173] (3) Weigh 0.157 g of silver nitrate and dissolve it in 65 g of deionized water, then add the semi-finished catalyst M to the Ag salt solution, and after the solution is completely absorbed, age it for 2 hours, dry it at 80° C., and calcine it at 550° C. for 4 hours to obtain the 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 the semi-finished catalyst O;

[0175] (5) Weigh 10 mg of palladium chloride and dissolve it in 65 g of deionized water, adjust the pH to 2.7, then add the semi-finished catalyst O to the prepared Pd salt solution, age it for 4 hours, dry it at 100° C., and calcine it at 520° C. for 6 hours to obtain the desired catalyst.

[0176] The particle size of the microemulsion prepared in steps (1) and (2) was 100.12 nm as measured by dynamic light scattering.

[0177] The prepared catalyst was measured 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%, with the carrier as 100%. The Pd content of the solution method was 0.006%, and the Pd content of the emulsion method was 0.006%.

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

[0179] Comparative Example 4

[0180] Carrier: Same as Example 4.

[0181] Catalyst: Same as Example 4.

[0182] Reduction: Before use, place it in a fixed bed reactor and use a mixed gas with a molar ratio of N2:H2=1:1 at 190°C for reduction treatment for 12 hours.

[0183] Evaluation test

[0184] Evaluation conditions of Example 4:

[0185] C2 raw materials: acetylene 0.8% (v / v), ethylene 75% (v / v), ethane 23.5% (v / v), methane 0.3% (v / v), C3 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 2.5MPa, catalyst loading, 100mL

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

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

[0190] The evaluation conditions of Comparative Example 4 are similar to those of Example 4, except for the CO content, which is 1.1% (v / v) in this comparative example.

[0191] Evaluation conditions:

[0192] C2 raw materials: acetylene 0.8% (v / v), ethylene 75% (v / v), ethane 23.5% (v / v), methane 0.3% (v / v), C3 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 2.5MPa, catalyst loading 100mL

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

[0196] The CO content in the first stage of the hydrogenation material is 220ppm, and no hydrogen is added in the second stage.

[0197] Table 6 Evaluation results

[0198]

[0199] From the evaluation results of Table 6, in the initial stage of the reactor, under the conditions of CO content of 120ppm, hydrogen / alkyne of 2, and space velocity of 4500 / h, the conversion rate of the first stage of the embodiment was 81.0%, the actual amount of alkyne removal was 0.645%, and the hydrogen / alkyne at the first stage outlet reached 5.92, which was much higher than the hydrogen / alkyne at the first stage inlet, indicating that the presence of CO improved the selectivity of the reaction, and while acetylene was hydrogenated, there were few side reactions of ethylene hydrogenation, so that the second stage did not need to be equipped with hydrogen. The acetylene content at the second stage outlet was lower than 1ppm, indicating that when CO and acetylene had a significant competitive adsorption effect, the catalyst had sufficient alkyne removal ability and could completely convert acetylene.

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

[0201] The evaluation conditions of Comparative Example 4 and Example 4 are completely the same, except that the CO content of the hydrogenated material is different due to the different CO content in the hydrogen. The CO in the material of Example 4 is 120ppm, and the CO in the material of Comparative Example 4 is 220ppm. From the evaluation results of the first 24 hours, the acetylene at the outlet of the first stage of Comparative Example 4 is higher than that of the embodiment, and the hydrogen / alkyne 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 it is still conducive to the hydrogenation of the second stage under this condition. The acetylene content at the outlet of the second stage is 1.5ppm, which meets the target requirements. Since the inlet temperature of the second stage is 110℃, which is the highest acceptable temperature, it shows that the catalyst's ability to remove alkynes has reached its upper limit under this operating condition.

[0202] After 1000 hours, the acetylene content at the outlet of the first stage of Comparative Example 4 was higher than that at the initial stage, and the hydrogen / acetylene ratio at the outlet decreased to below 3.0, indicating that the performance of the first stage catalyst was reduced. The catalyst performance decay rate was faster than that of Example 4, which may be due to the high CO content and the large number of by-products generated. The acetylene content at the outlet of the second stage exceeded the standard, which also showed that the low hydrogen / acetylene ratio was also reduced under the condition of high CO content.

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

[0204] From the perspective of the amount of coking generated, the coking amount of each stage of the catalyst in Example 4 and Comparative Example 4 did not exceed 10%, indicating that although the catalyst performance was reduced, it should not be seriously reduced. In Example 4, the amount of coking in the first stage was higher than that in the second stage, indicating that the hydrogenation load of the first stage was higher than that of the second stage; but in the comparative example, on the contrary, the amount of coking in the second stage was higher than that in the first stage, indicating that the load of the second stage was higher than that of the first stage. This may be due to the fact that the hydroformylation reaction of CO became more intense as the temperature increased, generating more by-products.

[0205] Example 5

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

[0207] Catalyst preparation:

[0208] (1) Weigh 0.315 g of silver nitrate and dissolve it in 50 g of deionized water. Then add 100 g of the calcined carrier to the Ag salt solution. After the solution is completely absorbed, age it for 2 hours, dry it at 60° C., and calcine it at 450° C. for 4 hours to obtain a semi-finished catalyst P.

[0209] (2) Weigh 7.82 g of ferric nitrate and dissolve it in 50 g of deionized water, add the semi-finished catalyst P to the prepared Fe salt solution, dry at 100° C. after the solution is completely absorbed, and calcine at 400° C. for 6 hours to obtain the semi-finished catalyst Q;

[0210] (3) Weighing 11.66 mg of palladium chloride and dissolving it in 60 g of deionized water, adjusting the pH to 2.1, then adding the semi-finished catalyst Q into the Pd salt solution, aging for 10 hours, drying at 80° C., and calcining at 400° C. for 4 hours to obtain the semi-finished catalyst R;

[0211] (4) Take 11.05g of nickel chloride, dissolve it in 45ml of deionized water, add 12.86g of n-hexane, 1.54g of CTAB, and 1.29g of n-pentanol, stir thoroughly to form a microemulsion, and immerse the semi-finished catalyst R into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 100°C, and calcine it at 450°C for 5h to obtain the semi-finished catalyst S;

[0212] (5) Weigh 10.87 mg of palladium nitrate and dissolve it in 45 ml of deionized water. Add 12.86 g of n-hexane, 1.54 g of CTAB, and 1.29 g of n-pentanol, and stir thoroughly to form a microemulsion. Impregnate the semi-finished catalyst S into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 100° C. and calcine it at 400° C. for 4 hours to obtain the desired catalyst.

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

[0214] The prepared catalyst was measured by atomic absorption spectrometry, and calculated based on the carrier as 100%, in Example 5, the Pd content was 0.012%, the Ni content was 5.0%, the Fe content was 1.8%, and the Ag content was 0.2%. 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 with a mixed gas with a molar ratio of N2:H2=1:1 at 220°C for 12 hours.

[0216] Comparative Example 5

[0217] Carrier: Same as Example 5.

[0218] Catalyst: Same as Example 5.

[0219] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at 220°C for 12 hours.

[0220] Evaluation test

[0221] Evaluation conditions of Example 5:

[0222] C2 raw materials: acetylene 1.3% (v / v), ethylene 80% (v / v), ethane 18.5% (v / v), methane 0.1% (v / v), C3 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 2.3MPa, catalyst loading 100mL

[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 / alkyne 1.5;

[0226] The CO content in the first stage of the hydrogenation material is 195ppm, and no hydrogen is added in the second and third stages.

[0227] Evaluation conditions of Comparative Example 5:

[0228] C2 raw materials: acetylene 1.3% (v / v), ethylene 80% (v / v), ethane 18.5% (v / v), methane 0.1% (v / v), C3 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 2.3MPa, catalyst loading 100mL

[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 / alkyne 1.2;

[0232] The CO content in the first stage of the hydrogenation material is 156ppm, and no hydrogen is added in the second and third stages.

[0233] Table 7 Evaluation results

[0234]

[0235] From the evaluation results in Table 7, it can be seen that the hydrogen / alkyne ratio at the first outlet of Example 5 is 1.84, and the hydrogen / alkyne ratio at the second outlet is 5.79, that is, the hydrogen / alkyne ratio becomes higher and higher toward the rear end, especially the hydrogen / alkyne ratio at the second outlet, which is much higher than 3, and the temperature of the third stage is the highest, which is very conducive to the complete conversion of acetylene in the third stage.

[0236] Compared with Example 5, the ratio of hydrogen to alkyne at the first stage inlet of Comparative Example 5 is low, and thus less CO is introduced, so the acetylene conversion rate of the first and second stages of Comparative Example 5 is higher than that of Example 5. The ratio of hydrogen to alkyne at the first and second stage outlets of the Comparative Example is 1.35 and 2.38, respectively, both higher than the ratio of hydrogen to alkyne at the first stage inlet, and also getting higher and higher. However, since the ratio of hydrogen to alkyne at the second stage outlet of the Comparative Example is lower than 3, although the temperature at the third stage inlet has reached 110°C, due to the lack of hydrogen, the catalyst cannot completely convert acetylene even when it reaches the highest activity.

[0237] From the selectivity point of view, after 1000 hours, the total selectivity of Comparative Example 5 reached 86.9%. Without considering the conversion of acetylene, its selectivity was higher than that of Example 5. This may be because the amount of hydrogen in each stage of the reactor of Comparative Example 5 was less than that in each stage of the reactor of Example 5, so its hydrogen consumption was also less, and its total selectivity was better. Since the CO content of Example 5 was higher, the selectivity was lower than that of Comparative Example 5, indicating that when the hydrogen was too little, the factor affecting the hydrogen consumption was not the CO content, but the hydrogen amount. However, it was precisely because the hydrogen in the comparative example was too little that the hydrogen / acetylene at the inlet of the last stage was lower than the limit value, and acetylene could not be completely converted.

[0238] It can also be seen from Table 7 that the CO content at the first stage inlet of Example 5 and Comparative Example 5 is quite different, but the difference in the acetylene conversion rate at the first stage is relatively small. From this, an important conclusion can be drawn, that is, when Fe is the main active component, its hydrogenation activity is less sensitive to the CO content, which is an advantage for the hydrogenation reaction using crude hydrogen as the hydrogen source. In other words, the change in CO content will not cause a more drastic change in the catalyst activity, which is beneficial to the stability of the reaction. As long as there is enough hydrogen at the reactor inlet, under the condition of multi-stage hydrogenation, the rear-end reactor does not need to be equipped with hydrogen, and acetylene can be stably and completely converted, which is of great significance to the stable operation of the ethylene unit.

[0239] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for selective hydrogenation of a carbon distillate, wherein the carbon distillate and hydrogen are selectively hydrogenated in a hydrogenation reactor containing a catalyst, wherein the process conditions for the selective hydrogenation reaction are: a reactor inlet temperature of 55 to 110° C., a reaction pressure of 1.5 to 3.0 MPa, and a gas volume space velocity of 1000 to 5000 h -1 ; It is characterized by: The volume ratio of hydrogen to alkyne at the reactor inlet is 1.3-3.0, the hydrogen comes from crude hydrogen, and the CO content in the crude hydrogen is 0.1%-1%. The catalyst used in the selective hydrogenation reaction is alumina or mainly alumina, with a specific surface area of ​​15 to 40 m 2 / g, having a bimodal pore size distribution characteristic, with a small pore size of 20-60nm and a large pore size of 70-600nm; the active components include Pd, Ni and Fe, Pd is loaded by both microemulsion method and solution method, Ni is loaded by microemulsion method, and Fe is loaded by solution method; and the solution method loads Pd after the solution method loads Fe, and the microemulsion method loads Pd after the microemulsion method loads Ni; the microemulsion method loads Pd and Ni in the large pores, and the solution method loads Fe and Pd in ​​the small pores; Taking the mass of the carrier as 100%, the Ni content is 1.0% to 5%, the Fe content is 1% to 2.5%, and the Pd content is 0.007% to 0.018%; wherein the Pd content loaded by the solution method is 0.005% to 0.01%, and the Pd content loaded by the microemulsion method is 0.002% to 0.008%; The catalyst is reduced at 180-230°C before being put into the selective hydrogenation reaction.

2. The method for selective hydrogenation of carbon distillate according to claim 1, characterized in that: The carbon two fraction comes from the top of the front deethanizer tower, and based on the total volume of the carbon two fraction being 100%, the ethylene content is 60% to 90% and the acetylene content is 0.1% to 1.5%.

3. The method for selective hydrogenation of carbon distillate according to claim 1, characterized in that: The hydrogenation reactor is a fixed bed hydrogenation reactor, and the fixed bed reactor is an adiabatic or isothermal reactor.

4. The method for selective hydrogenation of carbon distillate according to claim 1, characterized in that: The selective hydrogenation reaction is single-stage hydrogenation, two-stage hydrogenation or three-stage hydrogenation; in the two-stage hydrogenation, the second stage does not add hydrogen; in the three-stage hydrogenation, the third stage does not add hydrogen or adds a small amount of hydrogen.

5. The method for selective hydrogenation of carbon two fractions according to claim 1, characterized in that: The process of loading Ni or Pd by microemulsion method comprises the following steps: dissolving Ni precursor salt or Pd precursor salt 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.

6. The method for selective hydrogenation of carbon two fractions according to claim 5, characterized in that: The mass ratio of the water 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.

7. The method for selective hydrogenation of carbon dioxide fraction according to claim 5, characterized in that: The oil phase is a C6-C8 saturated alkane or cycloalkane, preferably cyclohexane or n-hexane; The surfactant is an ionic surfactant and / or a nonionic surfactant, preferably a nonionic surfactant, more preferably polyethylene glycol octylphenyl ether or hexadecyltrimethylammonium bromide; The co-surfactant is an organic alcohol; preferably C4-C6 alcohols, more preferably n-butanol and / or n-pentanol.

8. The method for selective hydrogenation of carbon two fractions according to claim 1, characterized in that: The sequence of loading the active component into the carrier comprises the following steps: Microemulsion loading of Ni, solution method loading of Fe, solution method loading of Pd, microemulsion method loading of Pd; or Microemulsion loading of Ni, solution method loading of Fe, microemulsion method loading of Pd, solution method loading of Pd; or Solution method loading Fe, solution method loading Pd, microemulsion loading Ni, microemulsion loading Pd; or Microemulsion loading of Ni, microemulsion method loading of Pd, solution method loading of Fe, solution method loading of Pd.

9. The method for selective hydrogenation of carbon two fractions according to claim 1, characterized in that: The active components in the catalyst also include Ag, and the Ag is supported by a solution method.

10. The method for selective hydrogenation of carbon two fractions according to claim 9, characterized in that: Taking the mass of the carrier as 100%, the Ag content is 0.1% to 0.3%.

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