A nickel-based catalyst and its preparation method and use

Abstract

A nickel-based catalyst precursor comprises an active component, an adhesive, and a composite carrier, wherein the active component is a mixture of nickel and magnesium oxide, and the composite carrier is one or more of silicon oxide, aluminum oxide, cerium oxide, zirconium oxide, and molecular sieve, and is obtained by spray molding, and can efficiently and stably remove sulfur from benzene. The present invention also provides a method for preparing the above-mentioned catalyst precursor, comprising the steps of: 1) taking materials in proportion, stirring and mixing the other components except the adhesive in deionized water to obtain a suspension A, wherein the solid content of the suspension A is 30-50wt%; 2) the suspension A is homogeneously dispersed for 1-3h under cold water bath conditions; 3) the adhesive is added, and the amount of the adhesive added is 1-5%, to form a suspension B; 4) the suspension B is homogeneously dispersed for 1-3h under cold water bath conditions; 5) the suspension B is spray-molded. The active component is more evenly dispersed, the obtained product pores are larger, which is conducive to the diffusion of the reaction raw materials, the preparation process is simple, the processing cost is low, and the three wastes generated are less.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to a nickel-based catalyst and a preparation method and application thereof. Background Art

[0002] Benzene is an important chemical raw material, which usually contains a certain amount of sulfur impurities.

[0003] When benzene is used as a raw material to synthesize target products, precious metals are used as catalysts. The sulfur contained in benzene reacts with the precious metal catalyst to generate stable sulfides, which reduces the active centers of the catalyst. The generated sulfides easily block the pores of the catalyst, causing catalyst poisoning or even deactivation, resulting in the need for frequent regeneration or replacement of precious metal catalysts, which seriously affects the normal production of chemical companies and leads to high production costs.

[0004] Therefore, how to efficiently and stably remove sulfur, especially organic sulfur such as thiophene, from raw benzene is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] One of the purposes of the present invention is to provide a nickel-based catalyst precursor that can efficiently and stably remove sulfur from benzene in view of the deficiencies of the prior art.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned nickel-based catalyst precursor. The catalyst is prepared by a spray molding scheme. Compared with the catalyst prepared by the impregnation method, the active components are more evenly dispersed, the pores of the obtained product are larger, which is conducive to the diffusion of the reaction raw materials. The preparation process is simple, the processing cost is low, and less three wastes are generated.

[0007] The present invention also provides a use of the above-mentioned nickel-based catalyst precursor or the prepared nickel-based catalyst for removing sulfur from benzene, which can efficiently remove sulfur from benzene under mild conditions, so that the sulfur content in the treated benzene is less than 10 ppb, meeting the actual needs of enterprises.

[0008] The technical solution for achieving one of the purposes of the present invention is: a nickel-based catalyst precursor, including an active component, a binder, and a composite carrier, wherein the active component is a mixture of nickel and magnesium oxide, and the composite carrier is one or more of silicon oxide, aluminum oxide, cerium oxide, zirconium oxide, and molecular sieve, and is obtained by spray molding.

[0009] Furthermore, it also includes a composite auxiliary agent, which is one or more of lanthanum, cerium, praseodymium, neodymium, samarium, and neodymium rare earth oxides.

[0010] Preferably, the mass ratio of nickel to magnesium oxide in the active component is 30-80:1-30, the mass ratio of nickel to the composite carrier in the active component is 30-80:30-60, and the mass ratio of nickel to the composite auxiliary agent in the active component is 30-80:1-30.

[0011] Preferably, the adhesive is one or more of gum arabic, sesbania powder, starch and citric acid.

[0012] Preferably, the molecular sieve is one or more of ZSM-5, MCM-22, USY, β molecular sieve, MCM-41 and SBA-15.

[0013] Furthermore, the precursor of nickel is one or more of nickel sulfate, nickel chloride, nickel carbonate, nickel acetate, and nickel nitrate, the precursor of magnesium oxide is one or more of light magnesium oxide and heavy magnesium oxide, and the precursor of the composite additive is one or more of nitrate, hydroxide, and oxide.

[0014] The present invention also provides a nickel-based catalyst, which is prepared by using any of the above nickel-based catalyst precursors through extrusion, drying, molding, reduction and passivation.

[0015] The technical solution for achieving the second object of the present invention is: a method for preparing any of the above nickel-based catalyst precursors comprises the following steps:

[0016] 1) Take materials according to proportion, stir and mix the other components except the binder in deionized water to obtain suspension A, and the solid content of suspension A is 30-50wt%;

[0017] 2) Suspension A is homogenized and dispersed in a cold water bath for 1-3 hours;

[0018] 3) Adding an adhesive in an amount of 1-5% to form a suspension B;

[0019] 4) Suspension B is homogenized and dispersed in a cold water bath for 1-3 hours;

[0020] 5) The suspension B is sprayed to obtain a nickel-based catalyst precursor.

[0021] The present invention also provides use of any of the above nickel-based catalyst precursors or nickel-based catalysts for removing sulfur from benzene.

[0022] Furthermore, the removal method is to contact with a nickel-based catalyst precursor or a nickel-based catalyst at 40-200° C. and under a pressure of 0.2 MPa-1.5 MPa for 0.1 h-10 h.

[0023] The above technical solution has the following beneficial effects:

[0024] 1. The nickel-based catalyst precursor of the present invention provides micropores and mesopores through a composite carrier, and provides macropores and stacked pores through a binder, thereby forming a nickel-based catalyst precursor with a multi-pore distribution, which can effectively meet the purpose of desulfurization of benzene solutions with different sulfur contents, especially thiophene.

[0025] 2. The nickel-based catalyst precursor of the present invention is further added with a composite auxiliary agent to make the active site of the catalyst more stable, and the active nickel microcrystalline particles are not easy to aggregate and grow, so that the desulfurization activity of the catalyst remains stable.

[0026] 3. The nickel-based catalyst precursor of the present invention is prepared by a spray molding method, which makes the active metal nickel crystals smaller in size and more evenly dispersed, so that there are more active sites with desulfurization performance, and the sulfur in the raw material benzene can be removed efficiently and stably. The sulfur in the adsorbed benzene, especially thiophene, has a higher concentration and a larger sulfur capacity. It also has the advantages of lower adsorption temperature and lower price for desulfurization per unit weight of catalyst.

[0027] 4. The nickel-based catalyst precursor of the present invention limits the content and ratio of each component. If the content of nickel and magnesium oxide active components is too low, it will lead to fewer active sites and worse sulfur adsorption performance. The composite auxiliary agent needs to reach a limited ratio to completely block the aggregation of nickel crystallites, so as to ensure the initial activity and long-term activity of the catalyst. The specific ratio of the composite carrier and the adhesive provides a balanced ratio of micropores, mesopores and macropores, which can better disperse the active sites. If other ratios are used, the active sites will be unevenly dispersed and the desulfurization activity will be reduced.

[0028] 5. The method for preparing the nickel-based catalyst precursor of the present invention is prepared by a spray molding scheme. Compared with the catalyst prepared by the impregnation method, the catalyst precursor prepared by this method has a more uniform dispersion of active metals, and the obtained product has larger pores, which is conducive to the diffusion of the reaction raw materials; compared with the catalyst precursor prepared by the precipitation method, this method has a simpler preparation process, lower processing cost, and less waste.

[0029] The applicant has verified through experiments that the nickel-based catalyst precursor or nickel-based catalyst prepared by the present invention can effectively remove sulfur from benzene to a content below 10 ppb at 40-200°C and 0.2 MPa-1.5 MPa pressure conditions, thus meeting the actual needs of enterprises.

[0030] The following is a further description in conjunction with specific implementation methods. Implementation

[0031] In the present invention, the equipment or parts without specific structure are usually conventional equipment or parts in the chemical industry, and the specific connection method is usually conventional connection method in the chemical industry or connection method recommended by the manufacturer. The raw materials used meet the requirements of relevant national or industry standards. Example 1

[0032] Weigh 101.1 g nickel carbonate, 5 g magnesium oxide, 2.99 g lanthanum nitrate, 3.83 g praseodymium nitrate and 24 g γ-Al 2 O 3 , added to 150g of deionized water, stirred in a homogenizer for 3h in a cold water bath; then added 20g of molecular sieve MCM-22, 2.5g of sesbania powder and 2.5g of citric acid, continued to stir in the homogenizer for 3h, and then sprayed in a spray molding machine to obtain a nickel-based catalyst precursor. The obtained nickel-based precursor is kneaded, extruded, dried, shaped, calcined, reduced and passivated to obtain a granular nickel-based catalyst. Example 2

[0033] The nickel precursor or granular nickel catalyst prepared in Example 1 was used to remove raw benzene with a thiophene concentration of 10 ppm in a conventional desulfurization tower at 120°C and 0.5 MPa. The residence time was 0.1 h-10 h, and separated benzene was obtained at the bottom of the tower. The thiophene concentration was <10 ppb. The sulfur capacity of the nickel precursor or granular nickel catalyst was 12.5 g / kg. Example 3

[0034] Weigh 60.66g nickel carbonate, 10g magnesium oxide, 2.99g lanthanum nitrate, 3.83g praseodymium nitrate and 33g γ-Al 2 O 3 , added to 150g of deionized water, stirred in a homogenizer for 3h under a cold water bath; then added 26g of molecular sieve MCM-22, 3.5g of sesbania powder and 3.5g of citric acid, continued to stir in the homogenizer for 3h, and then sprayed in a spray molding machine to obtain a nickel-based catalyst precursor. The obtained nickel-based precursor is kneaded, extruded, dried, shaped, calcined, reduced and passivated to obtain a granular nickel-based catalyst. Example 4

[0035] The nickel-based catalyst precursor or granular nickel-based catalyst prepared in Example 1 was used to remove raw benzene with a thiophene concentration of 10 ppm in a conventional desulfurization tower at 120° C. and 0.5 MPa pressure. The residence time was 0.1 h-10 h, and separated benzene was obtained at the bottom of the tower. The thiophene concentration was <10 ppb. The sulfur capacity of the nickel-based catalyst precursor or granular nickel-based catalyst was 5.5 g / kg.

[0036] Comparative Example 1

[0037] Using a nickel-based catalyst directly tableted in industrial applications and the desulfurization conditions of Example 2, raw benzene with a thiophene concentration of 10 ppm was removed with a residence time of 0.1 h-10 h, and separated benzene was obtained at the bottom of the tower with a final sulfur capacity of 0.3 g / kg.

[0038] Comparative Example 2

[0039] Using a nickel-based catalyst directly extruded in industrial applications, the desulfurization conditions in Example 2 were adopted to remove raw benzene with a thiophene concentration of 10 ppm, with a residence time of 0.1 h-10 h, and separated benzene was obtained at the bottom of the tower with a final sulfur capacity of 0.4 g / kg.

Claims

1. A nickel-based catalyst for removing organic sulfur from benzene, characterized in that: Prepared according to the following method: 101.1 g of nickel carbonate, 5 g of magnesium oxide, 2.99 g of lanthanum nitrate, 3.83 g of praseodymium nitrate and 24 g of γ-Al2O3 were weighed and added to 150 g of deionized water. The mixture was stirred in a homogenizer for 3 h in a cold water bath. Then, 20 g of molecular sieve MCM-22, 2.5 g of sesbania powder and 2.5 g of citric acid were added and the mixture was stirred in the homogenizer for 3 h. The mixture was spray-formed in a spray-forming machine to obtain a nickel-based catalyst precursor. The obtained nickel-based precursor was kneaded, extruded, dried, shaped, calcined, reduced and passivated to obtain a granular nickel-based catalyst.

2. A nickel-based catalyst for removing organic sulfur from benzene, characterized in that: Prepared according to the following method: Weigh 60.66g of nickel carbonate, 10g of magnesium oxide, 2.99g of lanthanum nitrate, 3.83g of praseodymium nitrate and 33g of γ-Al2O3, add to 150g of deionized water, and stir in a homogenizer for 3h under a cold water bath; then add 26g of molecular sieve MCM-22, 3.5g of sesbania powder and 3.5g of citric acid, continue stirring in the homogenizer for 3h, and then spray-form in a spray-forming machine to obtain a nickel-based catalyst precursor. The obtained nickel-based precursor is kneaded, extruded, dried, shaped, calcined, reduced and passivated to obtain a granular nickel-based catalyst.

3. Use of the nickel-based catalyst according to claim 1 or 2 for removing organic sulfur from benzene.

4. The use according to claim 3, wherein the removal method is to preheat the sulfur-containing benzene to 40-200°C and contact it with a nickel-based catalyst at a pressure of 0.2 MPa-1.5 MPa for 0.1 h-10 h.