Highly dispersed supported ni-sn based catalysts and methods for their preparation

Abstract

The application belongs to the technical field of hydrogenation catalysts, and particularly relates to a high-dispersion supported Ni-Sn-based catalyst and a preparation method thereof. The high-dispersion supported Ni-Sn-based catalyst is composed of a carrier and a supported component, and the main active component is 5-10% by weight, the auxiliary active component is 10-40% by weight, and the carrier is 50-85% by weight. The main active component is a Ni salt, the auxiliary active component is a Sn salt, and the carrier is silicon oxide. The Ni salt is one of Ni(NO3)2·6H2O, NiCl2·6H2O and NiSO4·6H2O. The catalyst not only solves the problem of poor dispersity of alloy phase nanoparticles in the existing supported non-noble metal Ni-Sn-based catalytic system, but also reduces the loss rate of mono-olefins and the cost of Pd-based catalysts in the non-noble metal catalytic system.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation catalyst technology, specifically relating to a highly dispersed supported Ni-Sn-based catalyst and its preparation method. Background Technology

[0002] Alkylated oils possess advantages such as being free of aromatics, olefins, oxygen, sulfur, and having high octane numbers, low Reid vapor pressure, and good post-combustion cleanliness, making them ideal blending components for gasoline. Industrially, alkylation is commonly produced using the acid process, which involves the alkylation reaction of isobutane and butene under the catalysis of sulfuric acid or hydrofluoric acid.

[0003] Butadiene is a product of deep cracking. Refinery C4 fractions often contain several thousand ppm of butadiene, and with the increasing weighting of crude oil and the deepening of catalytic cracking in recent years, the butadiene content in C4 fractions has shown a gradual upward trend. In alkylation reactions, butadiene, under acid catalysis, tends to undergo chelation reactions rather than alkylation, producing large molecular hydrocarbons that dissolve in the acid phase to form ASO (acid-soluble mixed oil). It also reacts with acids to produce sulfate esters, which lower the octane number of low-alkylated oils and increase the sulfur content and dry point of alkylated oils, affecting stable plant operation and product quality.

[0004] Selective hydrogenation pretreatment of alkylation feedstocks, converting dienes into monoolefins under the action of hydrogen and a catalyst, can effectively limit the butadiene content in the feedstock to within 100 ppm, thus avoiding the dilution of sulfuric acid by byproducts and their impact on acid consumption. Currently, the industrially used selective hydrogenation catalyst for butadiene is an alumina-supported Pd catalyst. However, Pd is expensive, resulting in high catalyst costs, which is not conducive to large-scale promotion in the early stages. Therefore, in recent years, researchers have conducted more extensive research on inexpensive non-precious metal alternative catalysts.

[0005] Chinese patent CN105709786A, published on June 29, 2016, discloses a method for preparing a selective hydrogenation catalyst for 1,3-butadiene. This catalyst is a P-modified Ni-based catalyst supported on alumina. Under reaction conditions of 95℃, 1.8 MPa, and a hydrogen / butadiene molar ratio of 1.8, the butadiene conversion rate in mixed C4 is 71.4%, and the butene loss rate is 1.7%. Chinese patent CN108404916A, published on August 17, 2018, discloses a method for preparing a cobalt metal catalyst. Using sodium hypophosphite as a reducing agent, the cobalt metal catalyst is directly synthesized under atmospheric pressure and low temperature conditions. In the butadiene hydrogenation reaction, this catalyst achieves a butadiene conversion rate of 45.1% and a 1-butene selectivity of 78.2%. Chinese patent CN105399593A, published on March 16, 2016, discloses a method for producing 1-butene by hydrogenation of 1,3-butadiene from a C4 fraction. In the presence of hydrogen, under conditions of a reaction inlet temperature of 30℃-60℃, a reaction pressure of 0.6-3.5 MPa, a reaction space velocity (USV) of 10-60 h⁻¹ (measured by the liquid volume of the C4 fraction), and a hydrogen-to-1,3-butadiene molar ratio of 0.2-10, the liquid-phase C4 fraction is contacted with an activated composite catalyst in a fixed-bed reactor to prepare 1-butene. After hydrogenation, the butadiene content in the mixed C4 material is >1000 ppm, and the butene selectivity is approximately 76%.

[0006] In existing non-precious metal selective hydrogenation reactions of 1,3-butadiene, the loading of non-precious metals is typically much higher than that of metal Pd-based catalysts. This leads to a greater diversity and variability in catalytic active sites, often resulting in over-hydrogenation of 1-butene during butadiene hydrogenation, thus reducing the yield of the mono-olefin. Furthermore, in Ni-Sn catalysts prepared by impregnation, the interaction between Ni and Sn is weak, causing some Sn to fail to form a complete alloy with Ni. The isolated Sn that does not form an alloy phase will then form metallic tin after high-temperature reduction. Due to the low melting point of the metal (232℃), it will migrate into the support pores during high-temperature reduction, causing blockage of the pore structure. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a highly dispersed supported Ni-Sn-based catalyst, which not only solves the problem of poor dispersion of alloy phase nanoparticles in supported non-precious metal Ni-Sn catalytic systems, resulting in a reduction in the number of active hydrogenation particles, but also reduces the loss rate of monoolefins and the cost of Pd-based catalysts in non-precious metal catalytic systems.

[0008] Another objective of this invention is to provide a method for preparing a highly dispersed supported Ni-Sn-based catalyst, which not only has simple production steps but also mild preparation conditions, making it suitable for industrial production.

[0009] The technical solution adopted in this invention is:

[0010] The highly dispersed supported Ni-Sn-based catalyst is composed of a support and supported components, expressed as a percentage of total catalyst weight:

[0011] Main active ingredient 5-10%;

[0012] 10-40% of the active ingredients;

[0013] Carrier 50-85%;

[0014] The main active component is Ni salt, the auxiliary active component is Sn salt, and the support is silicon oxide.

[0015] The Ni salt is one of Ni(NO3)2·6H2O, NiCl2·6H2O, and NiSO4·6H2O.

[0016] The Sn salt is one of SnCl2·2H2O and SnCl4·5H2O.

[0017] The preparation method of the highly dispersed supported Ni-Sn-based catalyst includes the following steps:

[0018] (1) Dissolve Ni salt and Sn salt in deionized water to form an impregnation solution;

[0019] (2) Add a certain amount of triammonium citrate to the impregnation solution;

[0020] (3) Add silica microspheres to the impregnation solution, stir evenly, and let stand at room temperature to obtain the impregnation precursor;

[0021] (4) Dry the impregnation precursor in step (3), and then calcine it in a muffle furnace to obtain the product.

[0022] This method uses Ni 2+ and Sn 2+ Triammonium citrate is added to the impregnation solution, utilizing the reaction between triammonium citrate and Ni. 2+ and Sn 2+ Simultaneously, the complexation principle enhances the interaction between Ni and Sn and the dispersion of the Ni-Sn alloy phase. It solves the problems of low hydrogenation activity and large loss of monoolefins in the hydrogenation reaction of single metal Ni-Sn C4 selective hydrogenation catalysts in the existing technology.

[0023] The molar ratio of ammonium citrate to the total amount of Ni and Sn in the solution of step (1) is (0.6-3):(1-1.2).

[0024] The settling time in step (3) is 3-6 hours.

[0025] In step (4), the drying temperature is 60℃-120℃ and the drying time is 12-24h.

[0026] In step (4), the roasting temperature is 500-600℃ and the roasting time is 3-12h.

[0027] The highly dispersed supported Ni-Sn-based catalyst is mainly used for the selective hydrogenation of 1,3-butadiene to 1-butene in C4 fractions, in the presence of hydrogen, at a reaction temperature of 30-60℃, a reaction pressure of 1.5-2.0 MPa, and a reaction space velocity of 5-10 h⁻¹. -1 Under conditions where the molar ratio of hydrogen to 1,3-butadiene is 1-5, liquid C4 is contacted with an activated composite catalyst in a fixed-bed reactor.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) Through Ni 2+ and Sn 2+ Triammonium citrate is added to the impregnation solution, utilizing the reaction between triammonium citrate and Ni. 2+ and Sn 2+ Simultaneously, the complexation principle greatly enhances the interaction between Ni and Sn, the dispersion of the Ni-Sn alloy phase, and the number of hydrogenation active phases, thus significantly improving the reaction performance of the catalyst.

[0030] (2) It solves the problems of high single olefin loss rate and high cost of Pd catalyst in non-precious metal catalytic systems, and reduces production costs;

[0031] (3) The catalyst is simple to prepare and the reaction conditions are mild, which is conducive to industrial production. Attached Figure Description

[0032] Figure 1 The XRD patterns of the freshly prepared and reduced samples in the examples and comparative examples are shown below.

[0033] Figure 2 The above are H2-TPR curves for Comparative Example 1 and Example 2. Detailed Implementation

[0034] The present invention will be further described below with reference to the embodiments, but these embodiments do not limit the implementation of the present invention.

[0035] Example 1

[0036] 1. Weigh 19.46g of nickel nitrate hexahydrate and 15.10g of stannous chloride dihydrate, and dissolve them in 100g of deionized water;

[0037] 2. Weigh 16.28g of triammonium citrate and add it to the solution from step 1, stirring until completely dissolved;

[0038] 3. Add 85g of silica beads to the solution in step 2, stir well, and let stand at room temperature for 3 hours to obtain the precursor sample;

[0039] 4. After drying the precursor sample from step 3 at 60℃ for 24 hours, calcine it at 500℃ for 6 hours to obtain the final catalyst sample.

[0040] Example 2

[0041] 1. Weigh 31.81g of nickel chloride hexahydrate and 60.40g of stannous chloride dihydrate, and dissolve them in 200g of deionized water;

[0042] 2. Weigh 45.86g of triammonium citrate and add it to the solution from step 1, stirring until completely dissolved;

[0043] 3. Add 50g of silica beads to the solution in step 2, stir well, and let stand at room temperature for 6 hours to obtain the precursor sample;

[0044] 4. After drying the precursor sample from step 3 at 100℃ for 24 hours, calcine it at 600℃ for 12 hours to obtain the final catalyst sample.

[0045] Example 3

[0046] 1. Weigh 27.25g of nickel sulfate hexahydrate and 32.85g of tin chloride pentahydrate, and dissolve them in 150g of deionized water;

[0047] 2. Weigh 116.39g of triammonium citrate and add it to the solution from step 1, stirring until completely dissolved;

[0048] 3. Add 80g of silica spheres to the solution in step 2, stir well, and let stand at room temperature for 6 hours;

[0049] 4. The final material obtained is dried at 120℃ for 12 hours and calcined at 550℃ for 8 hours to obtain the finished catalyst.

[0050] Example 4

[0051] 1. Weigh 19.46g of nickel nitrate hexahydrate and 30.20g of stannous chloride dihydrate, and dissolve them in 100g of deionized water;

[0052] 2. Weigh 97.67g of triammonium citrate and add it to the solution from step 1, stirring until completely dissolved;

[0053] 3. Add 85g of silica beads to the solution in step 2, stir well, and let stand at room temperature for 6 hours;

[0054] 4. The final material obtained is dried at 60℃ for 24 hours and calcined at 600℃ for 6 hours to obtain the finished catalyst.

[0055] Example 5

[0056] 1. Weigh 23.25g of nickel sulfate hexahydrate and 30.85g of tin chloride pentahydrate, and dissolve them in 150g of deionized water;

[0057] 2. Weigh 67.36g of triammonium citrate and add it to the solution from step 1, stirring until completely dissolved;

[0058] 3. Add 76g of silica spheres to the solution in step 2, stir well, and let stand at room temperature for 6 hours;

[0059] 4. The final material obtained is dried at 60℃ for 24 hours and calcined at 500℃ for 12 hours to obtain the finished catalyst.

[0060] Comparative Example 1

[0061] 1. Weigh 31.81g of nickel chloride hexahydrate and 60.40g of stannous chloride dihydrate and dissolve them in 200g of deionized water;

[0062] 2. Add 50g of silica spheres to the solution in step 1, stir well, and let stand at room temperature for 6 hours;

[0063] 3. After drying the precursor sample from step 2 at 100℃ for 24 hours, calcine it at 600℃ for 12 hours to obtain the final catalyst sample.

[0064] Performance testing:

[0065] Take 15 mL of the catalyst described in Examples 1-5 and Comparative Example 1, pack it into a fixed-bed reactor, and carry out selective hydrogenation of the catalytic C4 fraction containing 0.56% butadiene by mass in a continuous manner (C4 fraction composition is shown in Table 1). The operating conditions are as follows:

[0066] Reaction temperature: 40℃

[0067] Reaction pressure: 1.5 MPa

[0068] Raw material weight hourly space velocity: 10h -1

[0069] Hydrogen / butadiene molar ratio: 5:1

[0070] The results of the catalyst selection and hydrogenation performance evaluation are shown in Table 2.

[0071] Table 1. Composition of C4 fraction (wt%)

[0072]

[0073] Table 2. Evaluation results of hydrogenation performance of catalyst selection.

[0074]

[0075] This invention provides a highly dispersed supported Ni-Sn-based catalyst and its preparation method. By simultaneously complexing triammonium citrate with both the main active component and the co-active component, the interaction strength between the main and co-active components is enhanced, while simultaneously greatly improving the dispersibility of the Ni-Sn alloy phase formed after reduction, thus significantly improving the catalyst's reaction performance. Figure 1 The XRD patterns show that with the addition of ammonium citrate, the diffraction peaks of tin oxide and nickel oxide gradually broaden, and the peak intensities significantly decrease. This indicates that triammonium citrate can simultaneously and significantly promote the dispersion of the main active component NiO and the auxiliary active component SnO2. Meanwhile, the diffraction peaks of the Ni3Sn2 alloy phase formed after high-temperature reduction exhibit the same pattern, indicating that the dispersibility of the Ni3Sn2 alloy nanoparticles is greatly improved. Furthermore, from... Figure 2 The results show that the TPR curves of the sample with added triammonium citrate shift towards higher temperatures compared to the sample without added triammonium citrate, and the reduction process is more concentrated. This indicates enhanced interactions between the active component and the support, as well as enhanced interactions between the active component and the support. Reaction evaluation results indicate that this Ni-Sn catalyst significantly reduces catalyst costs while exhibiting high catalytic activity and a low butene hydrogenation loss rate.

Claims

1. A highly dispersed Ni-supported type The method for preparing Sn-based catalysts is characterized by, Includes the following steps: (1) Dissolve Ni salt and Sn salt in deionized water to form an impregnation solution; (2) Add a certain amount of triammonium citrate to the impregnation solution, wherein the molar ratio of the triammonium citrate to the total amount of Ni and Sn in the solution of step (1) is (0.6). 3): (1) 1.2); (3) Add silica microspheres to the impregnation solution, stir evenly, and let stand at room temperature to obtain the impregnation precursor; (4) Dry the impregnation precursor in step (3), and then calcine it in a muffle furnace to obtain the product; Of which, based on the total weight and weight percentage of the final catalyst, the main active component formed by the Ni salt is 5-10%, the auxiliary active component formed by the Sn salt is 10-40%, and the silica support is 50-85%.

2. The highly dispersed supported Ni according to claim 1 The method for preparing Sn-based catalysts is characterized by: The Ni salt is one of Ni(NO3)2·6H2O, NiCl2·6H2O, and NiSO4·6H2O.

3. The highly dispersed supported Ni according to claim 1 The method for preparing Sn-based catalysts is characterized by: The Sn salt is one of SnCl2·2H2O and SnCl4·5H2O.

4. The highly dispersed supported Ni according to claim 1 The method for preparing Sn-based catalysts is characterized by: The settling time in step (3) is 3 minutes. 6h.

5. The highly dispersed supported Ni according to claim 1 The method for preparing Sn-based catalysts is characterized by: The drying temperature in step (4) is 60°C. 120℃, drying time is 12 24 hours.

6. The highly dispersed supported Ni according to claim 1 The method for preparing Sn-based catalysts is characterized by: The roasting temperature in step (4) is 500°C. 600℃, roasting time is 3 12h.

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