C2 selective hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention relates to the field of C2 selective hydrogenation catalysts, and discloses a C2 selective hydrogenation catalyst as well as a preparation method and application thereof. The catalyst contains a carrier, and a first active component and a second active component which are loaded on the carrier, and is characterized in that the first active component is Pd, the second active component contains Ag, and in the C2 selective hydrogenation catalyst, the spacing of the crystal face (111) of the first active component Pd is 0.228-0.231 nm; wherein in terms of oxide, the content of the first active component is 0.023 to 0.058 wt%, and the content of the second active component is 0.046 to 0.172 wt%. The active components of the C2 selective hydrogenation catalyst are uniformly distributed on the surface of the carrier, so that the activity of the catalyst is greatly improved, the preparation method of the catalyst is very simple, and the production cost can be greatly reduced.

Description

Technical Field

[0001] The invention relates to the field of carbon two selective hydrogenation catalysts, and in particular to a carbon two selective hydrogenation catalyst and a preparation method and application thereof. Background Art

[0002] Petroleum hydrocarbon cracking is the main technology for industrial production of ethylene. In the process of petroleum hydrocarbon cracking, the ethylene produced by cracking still contains about 1% acetylene after a series of separation processes. Although the content is very low, it will have a great impact on the production of downstream products from ethylene. Therefore, the industry usually uses C2 selective hydrogenation catalysts to remove the small amount of acetylene in ethylene.

[0003] There are a large number of patent reports on the formulation and preparation process of carbon dihydrogenation catalysts.

[0004] For example, CN108014792A discloses a method for preparing a selective hydrogenation catalyst for carbon distillation: specifically, the method comprises: (1) dissolving a Ga compound in deionized water, impregnating a carrier for 1-24 hours, then directly drying the obtained sample, and calcining it at a temperature of 250-600°C after drying; (2) preparing a Pd compound into a solution, adjusting the pH value to 1.5-5, and loading it onto the precursor obtained in step (1) by spraying or impregnation, and then drying and calcining it; (3) preparing a compound of a metal active component into a solution, impregnating the precursor obtained in step (2), and then drying and calcining it.

[0005] However, the current industrial preparation process of C2 selective hydrogenation catalyst is: the main catalyst and the co-catalyst are impregnated, dried and calcined step by step. The disadvantages are: the preparation process is long; the second is that many equipments are required, the investment is large, and the equipment occupies a large space; the third is that the energy consumption is high, which is not conducive to energy conservation and emission reduction; the fourth is that the labor demand is large and the labor production efficiency is low; the fifth is that the production cost is high; the sixth is that there are many control links and the product quality is unstable.

[0006] In order to optimize the above six problems, it is urgent to develop a carbon-2 selective hydrogenation catalyst that can impregnate the main catalyst and the co-catalyst on the carrier at one time. Summary of the invention

[0007] The purpose of the present invention is to overcome the problems of long preparation process, high energy consumption and high cost of the C2 selective hydrogenation catalyst in the prior art, and to provide a C2 selective hydrogenation catalyst and its preparation method and application. The active components of the C2 selective hydrogenation catalyst are evenly distributed on the surface of the carrier, thereby greatly improving the catalyst activity, and the preparation method of the catalyst is very simple, which can greatly reduce the production cost.

[0008] The inventors of the present invention have discovered through extensive research that, during the impregnation process, the catalyst carrier is first modified with PVP (polyvinyl pyrrolidone) and acetylacetone, and then the obtained carrier is impregnated with active components and additives. This allows the prepared C2 selective hydrogenation catalyst to not only have an excellent acetylene conversion rate, but also significantly improve its ethylene selectivity.

[0009] The reason may be that the nitrogen atoms and carbonyl groups in PVP and the carbonyl groups in acetylacetone can firmly fix the active metal components, especially Pd and Ag ions. Therefore, by first covering the surface of the carrier with PVP and acetylacetone, it can be ensured that the active metal components are fixed on the surface of the carrier during the subsequent impregnation, and the PVP and acetylacetone can be completely decomposed and removed by the subsequent calcination step, thereby completing the present invention.

[0010] In order to achieve the above-mentioned object, the present invention provides a C2 selective hydrogenation catalyst on one hand, which comprises a carrier and a first active component and a second active component loaded on the carrier, wherein the first active component is Pd, the second active component comprises Ag, and in the C2 selective hydrogenation catalyst, the spacing of the (111) crystal plane of the first active component Pd is 0.228-0.231nm; wherein, calculated as oxide, the content of the first active component is 0.023-0.058% by weight, and the content of the second active component is 0.046-0.172% by weight.

[0011] Preferably, the spacing between the (111) crystal planes of the first active component Pd is 0.228-0.230 nm.

[0012] Preferably, the carrier is one or more of Al2O3, SiO2, MgO, TiO2, molecular sieve and activated carbon; more preferably, the carrier is Al2O3.

[0013] Preferably, the content of the first active component in the catalyst is 0.023-0.046 wt % calculated as oxide.

[0014] Preferably, the second active component further contains Au and / or Cu.

[0015] Preferably, the content of the second active component in the catalyst is 0.060-0.110 wt % calculated as oxide.

[0016] Preferably, the catalyst further contains an auxiliary agent; more preferably, the auxiliary agent is Bi and / or Ga.

[0017] Preferably, the content of the auxiliary agent in the catalyst is 0.010-0.035 wt % calculated as oxide.

[0018] The second aspect of the present invention provides a method for preparing the carbon two selective hydrogenation catalyst according to the first aspect of the present invention, wherein the method comprises the following steps:

[0019] 1) in the presence of a solvent, bringing PVP and acetylacetone into first contact with a catalyst support to obtain a modified support at least partially covered with PVP and acetylacetone on the surface of the catalyst support;

[0020] 2) contacting the modified support obtained in step 1) with a solution containing the first active component and the second active component for a second time to obtain a second contact product;

[0021] 3) calcining the second contact product obtained in step 2);

[0022] Wherein, the first active component is Pd, and the second active component contains Ag.

[0023] Preferably, in step 1), the molecular weight of the PVP is less than 10W; more preferably, the molecular weight of the PVP is 0.8W-5W.

[0024] Preferably, in step 2), the second active component further contains Au and / or Cu.

[0025] Preferably, the solution in step 2) further contains an auxiliary agent; more preferably, the auxiliary agent is Bi and / or Ga.

[0026] Preferably, the carrier is one or more of Al2O3, SiO2, MgO, TiO2, molecular sieve and activated carbon; more preferably, the carrier is Al2O3.

[0027] Preferably, in step 1), the solvent is an organic solvent and / or an inorganic solvent; more preferably, the solvent is one or more of water, methanol and ethanol.

[0028] Preferably, step 1) includes a step of first contacting the catalyst support with a solution containing PVP, acetylacetone and the solvent; more preferably, step 1) includes a step of immersing the catalyst support in a solution containing PVP, acetylacetone and the solvent.

[0029] Preferably, in step 1), the amount of PVP used is 0.05-10 g relative to 100 g of the carrier; more preferably, the amount of PVP used is 0.075-7.5 g relative to 100 g of the carrier.

[0030] Preferably, the amount of acetylacetone used is 0.01-0.5 g relative to 100 g of the carrier; more preferably, the amount of acetylacetone used is 0.03-0.15 g relative to 100 g of the carrier.

[0031] Preferably, the weight ratio of the PVP to the acetylacetone is 1:0.002-1.

[0032] Preferably, the amount of the solvent used is 20-100 mL relative to 100 g of the carrier; more preferably, the amount of the solvent used is 20-70 mL relative to 100 g of the carrier.

[0033] Preferably, in step 1), the first contacting time is 10-60 min; more preferably, the first contacting time is 20-30 min.

[0034] Preferably, the method further comprises: after the first contacting, performing a first drying treatment on the modified carrier; more preferably, the conditions of the first drying treatment comprise: a first drying temperature of 50-120°C, and a first drying time of 4-20h; further preferably, the conditions of the first drying treatment comprise: a first drying temperature of 60-100°C, and a first drying time of 6-10h.

[0035] Preferably, in step 2), the second contacting is performed so that the content of the first active component in the prepared catalyst, calculated as oxide, is 0.023-0.058 wt %; more preferably, the second contacting is performed so that the content of the first active component in the prepared catalyst, calculated as oxide, is 0.023-0.046 wt %.

[0036] Preferably, the second contacting results in a catalyst having a content of the second active component as oxide of 0.046-0.172 wt %; more preferably, the second contacting results in a catalyst having a content of the second active component as oxide of 0.060-0.110 wt %.

[0037] Preferably, the second contacting is performed so that the content of the promoter in the prepared catalyst, calculated as oxide, is 0.010-0.035 wt%.

[0038] Preferably, in step 2), the second contacting time is 10-60 min; more preferably, the second contacting time is 20-30 min.

[0039] Preferably, the method further comprises: after the second contact, performing a second drying treatment on the second contact product; more preferably, the conditions of the second drying treatment comprise: a second drying temperature of 100-200°C, and a second drying time of 10-60min; further preferably, the conditions of the second drying treatment comprise: a second drying temperature of 120-160°C, and a second drying time of 30-50min.

[0040] Preferably, in step 3), the conditions for the calcination treatment include: a calcination temperature of 300-600°C and a calcination time of 2-6h; more preferably, the conditions for the calcination treatment include: a calcination temperature of 400-500°C and a calcination time of 3-5h.

[0041] The third aspect of the present invention provides the use of the C2 selective hydrogenation catalyst described in the first aspect of the present invention or the C2 selective hydrogenation catalyst prepared by the method described in the second aspect of the present invention in the hydrogenation of acetylene to produce ethylene.

[0042] Through the above technical scheme, after the catalyst carrier is modified with PVP and acetylacetone, the active components and additives can be firmly fixed on the surface of the carrier during the subsequent impregnation process without entering the pores of the carrier, so that all active components and additives (if any) can be achieved through only one-step impregnation, and at the same time, the activity and selectivity of the prepared carbon two selective hydrogenation catalyst can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a picture of catalyst C1 under a scanning transmission electron microscope. DETAILED DESCRIPTION

[0044] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0045] A first aspect of the present invention provides a C2 selective hydrogenation catalyst, which comprises a carrier and a first active component and a second active component loaded on the carrier, wherein the first active component is Pd, the second active component comprises Ag, and the spacing of the (111) crystal planes of the first active component Pd in ​​the C2 selective hydrogenation catalyst is 0.228-0.231 nm, and the content of the first active component is 0.023-0.058 wt % and the content of the second active component is 0.046-0.172 wt % in terms of oxide.

[0046] In the present invention, preferably, the spacing of the (111) crystal planes of the first active component Pd in ​​the C2 selective hydrogenation catalyst is 0.228-0.230 nm. It can be seen from the (111) crystal plane spacing of the first active component Pd in ​​the C2 selective hydrogenation catalyst that the second active component in the C2 selective hydrogenation catalyst of the present invention enters the crystal lattice of the first active component.

[0047] According to the present invention, the carrier of the C2 selective hydrogenation catalyst can be various carriers conventionally used in the art for preparing selective hydrogenation catalysts, for example, the carrier can be one or more of Al2O3, SiO2, MgO, TiO2, molecular sieves and activated carbon. Preferably, the carrier is Al2O3. When Al2O3 is used as the carrier of the catalyst in the present invention, it can synergize with PVP, acetylacetone and the active components and additives described later to obtain a C2 selective hydrogenation catalyst with good specific surface area, pore volume and catalytic performance.

[0048] In the present invention, the active component of the catalyst may include a first active component and a second active component, and in order to improve the acetylene conversion rate of the carbon two selective hydrogenation catalyst, in the present invention, the first active component is Pd, and the second active component contains at least Ag, and the content of the first active component is 0.023-0.058% by weight, and the content of the second active component is 0.046-0.172% by weight, calculated as oxide. Thus, through the synergistic effect of Pd and Ag, the hydrogenation selectivity of the catalyst can be greatly improved while ensuring a high acetylene conversion rate.

[0049] In addition, in order to further improve the selectivity of the catalyst, preferably, the second active component also contains Au and / or Cu.

[0050] The combination of the first active component and the second active component may be, for example, a combination of Pd and Ag, a combination of Pd, Ag and Au, a combination of Pd, Ag and Cu, and a combination of Pd, Ag, Au and Cu.

[0051] In addition, in addition to the first active component and the second active component, the catalyst may further contain an auxiliary agent. More preferably, the auxiliary agent is Bi and / or Ga. By adding the auxiliary agent Bi and / or Ga, the selectivity of the carbon two selective hydrogenation catalyst can be further improved.

[0052] In addition, according to the present invention, in order to further ensure the catalytic performance of the catalyst, preferably, calculated as oxide, the content of the first active component in the hydrorefining catalyst is 0.023-0.046 wt%, and the content of the second active component in the hydrorefining catalyst is 0.060-0.110 wt%.

[0053] In addition, when the C2 selective hydrogenation catalyst further contains an auxiliary agent, the content of the auxiliary agent can be 0.010-0.035 wt % in terms of oxide; preferably, the content of the auxiliary agent is 0.015-0.025 wt % in terms of oxide. By controlling the content of the auxiliary agent within the above range, the auxiliary agent can further achieve better synergistic effects with the first active component and the second active component, thereby further improving the hydrogenation selectivity of the catalyst.

[0054] The second aspect of the present invention provides a method for preparing the carbon two selective hydrogenation catalyst according to the first aspect of the present invention, wherein the method comprises the following steps:

[0055] 1) in the presence of a solvent, bringing PVP and acetylacetone into first contact with a catalyst support to obtain a modified support having the surface of the catalyst support covered with PVP and acetylacetone;

[0056] 2) contacting the modified support obtained in step 1) with a solution containing the first active component and the second active component for a second time to obtain a second contact product;

[0057] 3) calcining the second contact product obtained in step 2);

[0058] Wherein, the first active component is Pd, and the second active component contains Ag.

[0059] First, the preparation steps of the modified carrier at least partially covered with PVP and acetylacetone in the present invention are described in detail.

[0060] In the present invention, the molecular weight of the PVP is not particularly limited, as long as it can cover the surface of the catalyst support in the presence of a solvent. In order to ensure that it has a suitable viscosity in the solvent, preferably, the molecular weight of the PVP is less than 10W; more preferably, the molecular weight of the PVP is 0.8W-5W.

[0061] In the present invention, the solvent in step 1) is not particularly limited, and may be any conventional solvent in the art capable of dissolving PVP and dispersing acetylacetone. For example, the solvent may be an organic solvent and / or an inorganic solvent.

[0062] As the inorganic solvent, water is preferred.

[0063] The organic solvent may be selected from one or more of an alcohol solvent, an ester solvent, an ether solvent and a ketone solvent. Preferably, the organic solvent is an alcohol solvent.

[0064] Preferably, the solvent is one or more of water, methanol and ethanol; more preferably, the solvent is water.

[0065] In the present invention, the catalyst carrier may be the same as the catalyst carrier described in the first aspect of the present invention, and will not be described in detail herein.

[0066] According to the preparation method of the present invention, in step 1), the amount of PVP and acetylacetone can vary within a wide range, as long as the surface of the catalyst support obtained after the first contact is at least partially covered with PVP and acetylacetone. In order to improve the catalytic performance of the prepared selective hydrogenation catalyst, preferably, the amount of PVP and acetylacetone is such that the surface of the catalyst support obtained after the first contact is completely covered with PVP and acetylacetone.

[0067] In order to ensure the coverage area of ​​PVP and acetylacetone on the surface of the carrier, preferably, relative to 100g of the carrier, the amount of PVP is 0.05-10g, and the amount of acetylacetone is 0.01-0.5g; more preferably, relative to 100g of the carrier, the amount of PVP is 0.075-7.5g, and the amount of acetylacetone is 0.03-0.15g.

[0068] In addition, in order to further improve the modification effect on the carrier and enhance the catalytic activity of the prepared catalyst, preferably, the weight ratio of the PVP to the acetylacetone is 1:0.002-1; more preferably, 1:0.004-0.4.

[0069] By limiting the amount of the PVP, acetylacetone and carrier to the above range, the uniform distribution of the surface active components and additives of the catalyst prepared subsequently can be ensured, thereby further improving the activity and selectivity of the catalyst.

[0070] In addition, the amount of the solvent used relative to the carrier can also vary within a wide range without particular limitation. However, in order to ensure the effect of the first contact, preferably, the amount of the solvent used relative to 100g of the carrier is 20-100mL; more preferably, the amount of the solvent used relative to 100g of the carrier is 20-70mL.

[0071] According to the present invention, there is no particular limitation on the method for the first contact, and it can be carried out according to conventional methods in the art. For example, PVP, acetylacetone and the solvent can be first mixed to prepare a solution containing PVP and acetylacetone, and then the carrier can be placed in the solution for the first contact; PVP, acetylacetone and the carrier can also be placed in the solvent at the same time for the first contact; the carrier can also be placed in the solvent first, and then the PVP and acetylacetone can be added thereto; or acetylacetone can be first mixed with the solvent, and then PVP and the carrier can be added thereto, etc.

[0072] In the present invention, in order to improve the covering effect of PVP and acetylacetone on the carrier surface, preferably, step 1) includes a step of first contacting a solution containing PVP, acetylacetone and the solvent with the catalyst carrier; more preferably, step 1) includes a step of immersing the catalyst carrier in a solution containing PVP, acetylacetone and the solvent.

[0073] Furthermore, the impregnation is preferably an equal volume impregnation.

[0074] In the present invention, there is no particular restriction on the conditions of the first contact. In order to improve the effect of the first contact, the surface of the catalyst carrier is completely covered with PVP and acetylacetone. Preferably, the first contact time is 10-60 min; more preferably, the first contact time is 20-30 min.

[0075] In the present invention, in order to make the PVP and acetylacetone cover the surface of the carrier more firmly, preferably, after the first contact is completed, the modified carrier is subjected to a first drying treatment.

[0076] The conditions of the first drying treatment may include: a first drying temperature of 50-120°C, a first drying time of 4-20 hours; preferably, the conditions of the first drying treatment include: a first drying temperature of 60-100°C, a first drying time of 6-10 hours. Thus, a modified carrier with PVP and acetylacetone covering the surface of the catalyst carrier can be obtained.

[0077] Next, the steps of preparing a C2 selective hydrogenation catalyst by a co-impregnation method using the modified carrier prepared by the above method are described in detail.

[0078] According to the present invention, the modified support obtained in step 1) is brought into second contact with a solution containing a first active component and a second active component to obtain a second contact product.

[0079] That is to say, in the present invention, the active components of the catalyst may include a first active component and a second active component, and in order to improve the acetylene conversion rate of the selective hydrogenation catalyst, in the present invention, the first active component is Pd, and the second active component contains at least Ag. Through the synergistic effect of Pd and Ag, the hydrogenation selectivity of the catalyst can be greatly improved while ensuring a high acetylene conversion rate.

[0080] In addition, in order to further improve the selectivity of the catalyst, preferably, the second active component also contains Au and / or Cu.

[0081] The combination of the first active component and the second active component may be, for example, a combination of Pd and Ag, a combination of Pd, Ag and Au, a combination of Pd, Ag and Cu, and a combination of Pd, Ag, Au and Cu.

[0082] In addition, in addition to the first active component and the second active component, an auxiliary agent may be further used. That is, the solution in step 2) may further contain an auxiliary agent.

[0083] Here, the auxiliary agent can be selected in the same manner as in the first aspect of the present invention, and will not be described in detail here.

[0084] According to the present invention, in order to ensure the performance of the prepared catalyst, preferably, the second contacting makes the content of the first active component in the prepared C2 selective hydrogenation catalyst calculated as oxide be 0.023-0.058 wt.%; more preferably, the second contacting makes the content of the first active component in the prepared C2 selective hydrogenation catalyst calculated as oxide be 0.023-0.046 wt.%.

[0085] In addition, preferably, the second contacting results in a content of the second active component in the prepared C2 selective hydrogenation catalyst, calculated as oxide, of 0.046-0.172 wt. %; more preferably, the second contacting results in a content of the second active component in the prepared C2 selective hydrogenation catalyst, calculated as oxide, of 0.060-0.110 wt. %.

[0086] In addition, when the solution in step 2) also contains an additive, preferably, the second contacting is performed so that the content of the additive in terms of oxide in the prepared C2 selective hydrogenation catalyst is 0.010-0.035 wt %; more preferably, the second contacting is performed so that the content of the additive in terms of oxide in the prepared C2 selective hydrogenation catalyst is 0.015-0.025 wt %.

[0087] In the present invention, there is no particular limitation on the conditions of the second contact, for example, the second contact time may be 10-60 minutes, preferably, the second contact time is 20-30 minutes. This ensures the content of the active component and the auxiliary agent (if any) in the prepared catalyst, thereby ensuring the catalytic ability of the catalyst.

[0088] The second contacting method is preferably equal volume immersion.

[0089] In addition, according to the present invention, the method further comprises: after the second contacting, performing a second drying treatment on the second contact product.

[0090] Preferably, the conditions of the second drying treatment include: the second drying temperature is 100-200°C, and the second drying time is 10-60min; more preferably, the conditions of the second drying treatment include: the second drying temperature is 120-160°C, and the second drying time is 30-50min.

[0091] Next, the second contact product after the second drying process is subjected to a calcination process.

[0092] The conditions for the calcination treatment are not particularly limited and can be conventionally selected in the art. For example, the conditions for the calcination treatment may include: a calcination temperature of 300-600°C and a calcination time of 2-6h; preferably, the conditions for the calcination treatment include: a calcination temperature of 400-500°C and a calcination time of 3-5h.

[0093] The third aspect of the present invention provides the use of the C2 selective hydrogenation catalyst described in the first aspect of the present invention or the C2 selective hydrogenation catalyst prepared by the method described in the second aspect of the present invention in selectively hydrogenating acetylene to produce ethylene in an acetylene-ethylene system.

[0094] The present invention will be described in detail below through examples.

[0095] In the following examples and comparative examples, unless otherwise specified, the raw materials used are conventional commercial products or prepared by conventional methods.

[0096] In the following examples and comparative examples, the metal content in the catalyst was measured by ICP emission spectroscopy.

[0097] In the following examples and comparative examples, the (111) interplanar spacing of the first active component Pd was measured using a scanning transmission electron microscope.

[0098] The molecular weight of PVP1 is 10000 and it was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with analytical purity;

[0099] The molecular weight of PVP2 is 58000 and it was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with analytical purity;

[0100] The molecular weight of PVP3 is 8000 and it was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with analytical purity.

[0101] Example 1

[0102] 1) 0.075 g of PVP1 was dissolved in 43 mL of deionized water, and then 0.03 g of acetylacetone was added and stirred until dissolved to obtain a first impregnation solution;

[0103] 2) In a coating machine, 43 mL of the first impregnation solution was evenly sprayed on 100 g of the Al2O3 carrier, and after rotating and impregnating in the coating machine for 20 min, it was dried at 60° C. for 10 h to obtain a modified carrier;

[0104] 3) Take 0.0650 g of palladium nitrate (analytical grade, excluding crystal water, the same below) and 0.1336 g of silver nitrate (analytical grade, the same below), add them into 47 mL of deionized water, stir to fully dissolve the palladium nitrate and silver nitrate, and obtain the second impregnation solution;

[0105] 4) In a coating machine, 47 mL of the impregnation solution obtained in step 3) was evenly sprayed on 100 g of the modified carrier obtained in step 1), and after rotating and impregnating in the coating machine for 30 min, it was dried at 120° C. for 50 min, and then calcined in a muffle furnace at 400° C. for 5 h to prepare catalyst C1.

[0106] In the obtained catalyst C1, the content of Pd was 0.035% by weight and the content of Ag was 0.091% by weight, calculated as oxides.

[0107] The image of catalyst C1 under scanning transmission electron microscope is as follows: Figure 1 Indicated by Figure 1 It can be seen that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst C1 is 0.228 nm.

[0108] Example 2

[0109] 1) 7.5 g of PVP1 was dissolved in 50 mL of deionized water, and then 0.03 g of acetylacetone was added and stirred until dissolved to obtain a first impregnation solution;

[0110] 2) In a coating machine, 50 mL of the first impregnation solution was evenly sprayed on 100 g of the Al2O3 carrier, and after rotating and impregnating in the coating machine for 10 min, it was dried at 80° C. for 8 h to obtain a modified carrier;

[0111] 3) adding 0.1000 g of palladium nitrate and 0.2200 g of silver nitrate into 50 mL of deionized water and stirring them thoroughly to dissolve them to obtain a second impregnation solution;

[0112] 4) In a coating machine, 50 mL of the impregnation solution obtained in step 3) was evenly sprayed on 100 g of the modified carrier obtained in step 2), and after rotating and impregnating in the coating machine for 15 min, it was dried at 150° C. for 40 min, and then calcined in a muffle furnace at 450° C. for 4 h to prepare catalyst C2.

[0113] In the obtained catalyst C2, the content of Pd was 0.053% by weight and the content of Ag was 0.150% by weight, calculated as oxides.

[0114] It can be seen from the image of catalyst C2 under a scanning transmission electron microscope that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst C2 is 0.230 nm.

[0115] Example 3

[0116] 1) 0.3750 g of PVP1 was dissolved in 48 mL of deionized water, and then 0.15 g of acetylacetone was added and stirred until dissolved to obtain a first impregnation solution;

[0117] 2) In a coating machine, 48 mL of the first impregnation liquid was evenly sprayed on 100 g of the Al2O3 carrier, and after rotating and impregnating in the coating machine for 30 min, it was dried at 100° C. for 6 h to obtain a modified carrier;

[0118] 3) adding 0.0430 g of palladium nitrate and 0.0793 g of silver nitrate into 40 mL of deionized water and stirring them thoroughly to dissolve them to obtain a second impregnation solution;

[0119] 4) In a coating machine, 40 mL of the impregnation solution obtained in step 3) was evenly sprayed on 100 g of the modified carrier obtained in step 1), and after rotating and impregnating in the coating machine for 20 min, it was dried at 160° C. for 30 min, and then calcined in a muffle furnace at 500° C. for 3 h to prepare catalyst C3.

[0120] In the obtained catalyst C3, the content of Pd was 0.023% by weight and the content of Ag was 0.054% by weight, calculated as oxides.

[0121] It can be seen from the picture of catalyst C3 under a scanning transmission electron microscope that the spacing between the 111 crystal planes of the first active component Pd in ​​catalyst C3 is 0.229 nm.

[0122] Example 4

[0123] The method described in Example 1 was followed, except that

[0124] In step 1), the amount of PVP1 in the first impregnation solution is 0.05 g, and the amount of acetylacetone is 0.01 g;

[0125] Catalyst C4 was prepared.

[0126] In the obtained catalyst C4, the content of Pd was 0.035% by weight and the content of Ag was 0.091% by weight, calculated as oxides.

[0127] It can be seen from the image of catalyst C4 under a scanning transmission electron microscope that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst C4 is 0.230 nm.

[0128] Example 5

[0129] The method described in Example 1 was followed, except that

[0130] In step 1), the amount of PVP1 in the first impregnation solution is 10 g, and the amount of acetylacetone is 0.2 g;

[0131] Catalyst C5 was prepared.

[0132] In the obtained catalyst C5, the content of Pd was 0.035% by weight and the content of Ag was 0.091% by weight, calculated as oxides.

[0133] It can be seen from the image of catalyst C5 under a scanning transmission electron microscope that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst C5 is 0.230 nm.

[0134] Example 6

[0135] The method described in Example 1 was followed, except that

[0136] In step 3), the preparation method of the second impregnation solution is:

[0137] Take 0.0650 g of palladium nitrate, 0.0958 g of silver nitrate and 0.0958 g of chloroauric acid, add them into 47 mL of deionized water, stir them thoroughly to dissolve the palladium nitrate, silver nitrate and chloroauric acid, and obtain a second impregnation solution.

[0138] Catalyst C6 was prepared.

[0139] In the obtained catalyst C6, the content of Pd, calculated as oxide, was 0.035 wt %, the content of Ag was 0.065 wt %, and the content of Au was 0.062 wt %.

[0140] It can be seen from the image of catalyst C6 under a scanning transmission electron microscope that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst C6 is 0.230 nm.

[0141] Example 7

[0142] The method described in Example 1 was followed, except that

[0143] In step 3), the preparation method of the second impregnation solution is:

[0144] Take 0.0650 g of palladium nitrate, 0.0719 g of silver nitrate, 0.0341 g of copper nitrate trihydrate and 0.0479 g of chloroauric acid, add them into 47 mL of deionized water, stir them thoroughly to dissolve the palladium nitrate, silver nitrate, copper nitrate and chloroauric acid, and obtain a second impregnation solution.

[0145] Catalyst C7 was prepared.

[0146] In the obtained catalyst C7, the content of Pd, calculated as oxide, was 0.035% by weight, the content of Ag was 0.049% by weight, the content of Cu was 0.011% by weight, and the content of Au was 0.031% by weight.

[0147] It can be seen from the picture of catalyst C7 under a scanning transmission electron microscope that the spacing between the 111 crystal planes of the first active component Pd in ​​catalyst C7 is 0.230 nm.

[0148] Example 8

[0149] The method described in Example 1 was followed, except that

[0150] In step 3), the preparation method of the second impregnation solution is:

[0151] Take 0.0650 g of palladium nitrate, 0.1198 g of silver nitrate and 0.0734 g of gallium nitrate, add them into 47 mL of deionized water, and stir them thoroughly to dissolve the palladium nitrate, silver nitrate and gallium nitrate to obtain a second impregnation solution.

[0152] Catalyst C8 was prepared.

[0153] In the obtained catalyst C8, the content of Pd, calculated as oxide, was 0.035 wt %, the content of Ag was 0.082 wt %, and the content of Ga was 0.027 wt %.

[0154] It can be seen from the image of catalyst C8 under a scanning transmission electron microscope that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst C8 is 0.229 nm.

[0155] Example 9

[0156] Catalyst C9 was prepared according to the method described in Example 1, except that PVP1 was replaced by PVP2.

[0157] In the obtained catalyst C9, the content of Pd was 0.035% by weight and the content of Ag was 0.091% by weight, calculated as oxides.

[0158] It can be seen from the image of catalyst C9 under a scanning transmission electron microscope that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst C9 is 0.229 nm.

[0159] Example 10

[0160] Catalyst C10 was prepared in the same manner as described in Example 1, except that PVP1 was replaced by PVP3.

[0161] In the obtained catalyst C10, the content of Pd was 0.035% by weight and the content of Ag was 0.091% by weight, calculated as oxides.

[0162] It can be seen from the picture of catalyst C10 under a scanning transmission electron microscope that the spacing between the 111 crystal planes of the first active component Pd in ​​catalyst C10 is 0.229 nm.

[0163] Comparative Example 1

[0164] The method described in Example 1 was followed, except that

[0165] The catalyst carrier is not subjected to the modification treatment of steps 1) and 2), that is, the second impregnation liquid is directly sprayed on the carrier.

[0166] Catalyst D1 was prepared.

[0167] In the obtained catalyst D1, the content of Pd was 0.035% by weight and the content of Ag was 0.091% by weight, calculated as oxides.

[0168] It can be seen from the image of catalyst D1 under a scanning transmission electron microscope that the spacing between the (111) crystal planes of the first active component Pd in ​​catalyst D1 is 0.225 nm.

[0169] Test Example 1

[0170] Catalytic performance test of C1-C10 and D1

[0171] The prepared catalysts C1-C10 and D1 were reduced with hydrogen. The reduction method was as follows: the catalyst was loaded into a reactor, the reactor temperature was raised to 180°C, and then hydrogen was introduced into the reactor to reduce the catalyst for 3-6 hours, the reactor was cooled to room temperature, and the introduction of hydrogen was stopped.

[0172] The activity of the catalyst was evaluated in a fixed bed microreactor. The specific method is as follows:

[0173] 0.5 g of catalyst was loaded into a stainless steel reactor with a volume of , and after replacing with nitrogen, the reaction raw materials were introduced into the reactor for acetylene selective hydrogenation reaction. The reaction conditions included: reaction temperature of 55 ° C, reaction pressure of 1.0 MPa, volume space velocity of 9000 h -1 .

[0174] The composition of the reaction raw materials is as follows:

[0175] Ethylene 92.907% by volume Acetylene 0.428 volume% Ethane 5.950% by volume hydrogen 0.715% by volume

[0176] The acetylene content, ethylene content and ethane content in the reactor outlet material were measured by gas chromatography.

[0177] The acetylene conversion C (%) and ethylene selectivity S (%) were calculated.

[0178] The acetylene content in the raw gas is expressed as C r ≡ The acetylene content in the product is expressed by C p ≡ Indicated by; the ethylene content in the raw material is expressed by C r ＝ The ethylene content in the product is expressed by C p ＝ Indicated by; the ethane content in the raw material is expressed by C r - The ethane content in the product is expressed by C p - express.

[0179] Since the molecular weights of ethylene, acetylene and ethane are similar and their influencing factors are extremely close under the same conditions, the integrated area is used to represent their respective contents.

[0180] C / % = [(C r ≡ -C p ≡ ) / C r ≡ ]×100%

[0181] S / % = {(C p ＝ -C r＝ ) / [(C p ＝ -C r ＝ )+(C p - -C r - )]}×100%

[0182] The test results are shown in Table 1.

[0183] Table 1

[0184] Catalyst No. Acetylene conversion rate C (%) Ethylene selectivity S (%) C1 98.50 64.50 C2 98.55 62.22 C3 98.43 63.15 C4 95.20 55.45 C5 94.78 56.57 C6 99.24 68.50 C7 99.35 65.31 C8 99.18 66.80 C9 94.38 56.89 C10 97.29 63.66 D1 80.20 53.20

[0185] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A C2 selective hydrogenation catalyst, comprising a carrier and a first active component and a second active component supported on the carrier, wherein the first active component is Pd, the second active component contains Ag, and in the C2 selective hydrogenation catalyst, the spacing between the (111) crystal planes of the first active component Pd is 0.228-0.231 nm; in, Calculated as oxide, the content of the first active component is 0.023-0.058% by weight, and the content of the second active component is 0.046-0.172% by weight.

2. The catalyst according to claim 1, wherein The spacing between the (111) crystal planes of the first active component Pd is 0.228-0.230 nm; Preferably, the carrier is one or more of Al2O3, SiO2, MgO, TiO2, molecular sieve and activated carbon; More preferably, the carrier is Al2O3.

3. The catalyst according to claim 1 or 2, wherein The content of the first active component in the catalyst is 0.023-0.046 wt % calculated as oxide; Preferably, the second active component further contains Au and / or Cu; Preferably, the content of the second active component in the catalyst is 0.060-0.110 wt % calculated as oxide; Preferably, the catalyst further contains an auxiliary agent; More preferably, the auxiliary agent is Bi and / or Ga; Preferably, the content of the auxiliary agent in the catalyst is 0.010-0.035 wt % calculated as oxide.

4. The method for preparing the C2 selective hydrogenation catalyst according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: 1) in the presence of a solvent, bringing PVP and acetylacetone into first contact with a catalyst support to obtain a modified support at least partially covered with PVP and acetylacetone on the surface of the catalyst support; 2) contacting the modified support obtained in step 1) with a solution containing the first active component and the second active component for a second time to obtain a second contact product; 3) calcining the second contact product obtained in step 2); Wherein, the first active component is Pd, and the second active component contains Ag.

5. The preparation method according to claim 4, wherein In step 1), the molecular weight of the PVP is less than 10W; Preferably, the molecular weight of the PVP is 0.8W-5W; Preferably, in step 2), the second active component further contains Au and / or Cu; Preferably, the solution in step 2) further contains an auxiliary agent; More preferably, the auxiliary agent is Bi and / or Ga; Preferably, the carrier is one or more of Al2O3, SiO2, MgO, TiO2, molecular sieve and activated carbon; More preferably, the carrier is Al2O3.

6. The preparation method according to claim 4 or 5, wherein: In step 1), the solvent is an organic solvent and / or an inorganic solvent; Preferably, the solvent is one or more of water, methanol and ethanol; Preferably, step 1) comprises the step of first contacting a solution containing PVP, acetylacetone and the solvent with the catalyst support; More preferably, step 1) comprises the step of impregnating the catalyst support in a solution containing PVP, acetylacetone and the solvent.

7. The preparation method according to any one of claims 4 to 6, wherein: In step 1), the amount of PVP is 0.05-10 g relative to 100 g of the carrier; Preferably, relative to 100g of the carrier, the amount of PVP is 0.075-7.5g; Preferably, relative to 100g of the carrier, the amount of acetylacetone is 0.01-0.5g; More preferably, the amount of acetylacetone is 0.03-0.15 g relative to 100 g of the carrier; Preferably, the weight ratio of the PVP to the acetylacetone is 1:0.002-1; Preferably, the amount of the solvent is 20-100 mL relative to 100 g of the carrier; More preferably, the amount of the solvent is 20-70 mL relative to 100 g of the carrier; Preferably, in step 1), the first contacting time is 10-60 min; More preferably, the first contacting time is 20-30 min; Preferably, the method further comprises: after the first contacting, performing a first drying treatment on the modified carrier; More preferably, the conditions of the first drying treatment include: a first drying temperature of 50-120° C., a first drying time of 4-20 h; Further preferably, the conditions of the first drying treatment include: a first drying temperature of 60-100° C., and a first drying time of 6-10 h.

8. The preparation method according to any one of claims 4 to 7, wherein: In step 2), the second contacting is performed so that the content of the first active component in the prepared catalyst is 0.023-0.058 wt % calculated as oxide; Preferably, the second contacting is performed so that the content of the first active component in the prepared catalyst is 0.023-0.046 wt % calculated as oxide; Preferably, the second contacting is performed so that the content of the second active component in the prepared catalyst calculated as oxide is 0.046-0.172 wt %; More preferably, the second contacting is performed so that the content of the second active component in the prepared catalyst calculated as oxide is 0.060-0.110 wt %; Preferably, the second contacting is performed so that the content of the promoter in the prepared catalyst, calculated as oxide, is 0.010-0.035 wt%.

9. The preparation method according to any one of claims 4 to 8, wherein: In step 2), the second contact time is 10-60 min; Preferably, the second contact time is 20-30 minutes; Preferably, the method further comprises: after the second contacting, performing a second drying treatment on the second contact product; More preferably, the conditions of the second drying treatment include: the second drying temperature is 100-200°C, and the second drying time is 10-60min; Further preferably, the conditions of the second drying treatment include: the second drying temperature is 120-160° C., and the second drying time is 30-50 min; Preferably, in step 3), the conditions of the calcination treatment include: a calcination temperature of 300-600° C. and a calcination time of 2-6 h; More preferably, the conditions of the calcination treatment include: a calcination temperature of 400-500° C. and a calcination time of 3-5 h.

10. Use of the C2 selective hydrogenation catalyst according to any one of claims 1 to 3 or the C2 selective hydrogenation catalyst prepared by the method according to any one of claims 4 to 9 in the hydrogenation of acetylene to produce ethylene.

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