High-density long-chain alkane dehydrogenation catalyst and preparation method thereof

Abstract

The invention belongs to the technical field of catalysis, and discloses a high-density long-chain alkane dehydrogenation catalyst and a preparation method thereof. The invention relates to a high-density long-chain alkane dehydrogenation catalyst, which is a composition of Pt, Sn, Ni, Fe and alkali metal or oxide thereof loaded by using mesoporous and microporous alumina as a carrier. The catalyst is mainly applied to the reaction process of preparing monoolefine through dehydrogenation of long-chain n-alkanes (C10-C13), the catalyst uses a ball-forming high-density carrier, the preparation process is safer and more environment-friendly, the dehydrogenation service life of the catalyst is prolonged, and the dehydrogenation stability is improved by 15-30%.

Description

Technical Field

[0001] The present invention belongs to the field of catalysis technology, and the present invention relates to a high-density long-chain alkane dehydrogenation catalyst and a preparation method thereof. The catalyst is used in the dehydrogenation reaction process of C10-C13 long-chain normal alkanes to produce monoolefins. Background Art

[0002] The detergent industry uses long-chain alkylbenzenes as the main raw material to produce anionic surfactant alkylbenzene sulfonates. The technical route for industrial production is long-chain alkane dehydrogenation-alkylation-alkylbenzene sulfonates. The key step is the dehydrogenation of long-chain alkanes to prepare linear monoolefins, so the long-chain alkane dehydrogenation catalyst is the core of this technology. The dehydrogenation catalyst initially used the DEH series catalyst of UOP Company in the United States. Nanjing Alkylbenzene Plant and Fushun Petrochemical Company in China achieved localization of dehydrogenation catalysts (NDC and DF series) in 1986 and 1996 respectively, and have done a lot of work in improving performance. There are many patents reported for long-chain alkane dehydrogenation catalysts, including US patents: US4,133,842(A); US4,458,098-A; British patent GB1456820; European patent EP0248130A1; British patent GB1456820; GB1,499,297; Chinese patents CN87101513A; CN1088482A; CN1031946A; CN1201715A; CN101642713A; CN1579616A; CN103055951A; CN104248960A; CN102451684B, etc. Most of the catalysts reported in these patents use Pt as the main active component, tin, lead, etc. as the second component, alkali metal or alkaline earth metal as the auxiliary agent, and macroporous drop ball forming alumina carrier. From the development and replacement of long-chain alkane dehydrogenation catalysts, we can see that domestic and foreign scientific research institutions and users have been researching and updating to tap the potential of catalysts. Existing long-chain alkane dehydrogenation catalysts still have problems such as short service life, instability, and harsh preparation process conditions. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a high-density long-chain alkane dehydrogenation catalyst and a preparation method thereof. The catalyst is mainly used in the reaction process of dehydrogenating long-chain normal alkanes (C10-C13) to produce monoolefins. The catalyst uses a ball-shaped high-density carrier, the preparation process is safer and more environmentally friendly, and is more conducive to improving the dehydrogenation life of the catalyst, and the dehydrogenation stability is improved by 15-30%.

[0004] The above object of the present invention is achieved through the following technical solutions:

[0005] The invention discloses a high-density long-chain alkane dehydrogenation catalyst, which is a composition of Pt, Sn, Ni, Fe and alkali metal or its oxide supported by medium- and microporous alumina.

[0006] The component contents of the high-density long-chain alkane dehydrogenation catalyst are calculated by element mass, specifically 0.35-0.55% Pt, 0.5-3.0% Sn, 2.0-10.0% Ni, 0.20-5.0% Fe, and 0.20-2.0% alkali metal.

[0007] The total pore volume of the medium and microporous alumina carrier used is 0.8-2.5 mL / g, the bulk density is 0.3-0.6 g / mL, and the specific surface area is 100-300 m 2 / g.

[0008] The above-mentioned medium and microporous alumina carrier is a high-density medium and microporous alumina carrier.

[0009] The preparation method of the above catalyst has the following specific steps:

[0010] (1) vacuum treating a high-density medium- and microporous alumina support for 0.5 to 1.0 h, then immersing it in an aqueous solution containing soluble salts of Pt, Sn, Ni, Fe and alkali metals, drying it in a 70-90° C. water bath for 0.5 to 1.0 h, drying it in an oven at 100 to 150° C. for 2 to 6 h, and finally calcining it in a muffle furnace at 500 to 540° C. for 4 to 8 h; obtaining product A;

[0011] (2) washing the product A obtained in the above step (1) in a steam-air mixture at 500-540° C. for 2-6 hours to obtain product B;

[0012] (3) The product B obtained above is reduced in pure hydrogen (purity>99.5%) with a water content of less than 20 ppm at 460-550° C. for 4-8 hours to obtain a catalyst.

[0013] Furthermore, in step (1), the alkali metal supported by the catalyst of the present invention is introduced as potassium chloride.

[0014] The present invention also claims to protect the use of the above catalyst in the dehydrogenation reaction process of long-chain normal alkanes (C10-C13) to produce monoolefins.

[0015] The beneficial effects of the present invention compared with the prior art are:

[0016] The high-density long-chain alkane dehydrogenation catalyst prepared by the preparation method of the present invention uses a high-density carrier formed by rolling balls, and the preparation process is safer and more environmentally friendly, and is more conducive to improving the dehydrogenation life of the catalyst, and the dehydrogenation stability is improved by 15-30%. DETAILED DESCRIPTION

[0017] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0018] In the embodiment: the carrier used in the present invention is a spherical γ-Al2O3 formed by rolling ball, and its technical specifications are:

[0019] Specific surface area: 200-300m 2 / g

[0020] Total pore volume: 0.8-1.5mL / g

[0021] Bulk density: 0.4-0.6g / mL

[0022] Water absorption rate: 1.0-2.0mL / g

[0023] Particle size: 1.5~2.5mm

[0024] Average pore size: 12-18nm.

[0025] The carrier of the traditional catalyst is a spherical macroporous γ-Al2O3 formed by drop-shaped spheres, and its technical specifications are:

[0026] Specific surface area: 150-200m 2 / g

[0027] Total pore volume: 1.0-2.0mL / g

[0028] Bulk density: 0.2-0.4g / mL

[0029] Water absorption rate: 1.0-2.0mL / g

[0030] Particle size: 1.5~2.5mm

[0031] Average pore size: 30-50nm.

[0032] Example 1

[0033] Preparation of high-density long-chain alkane dehydrogenation catalyst

[0034] 20g of high-density γ-Al2O3 was vacuum impregnated in 30mL of a mixed solution containing 0.35g of chloroplatinic acid, 0.30g of stannous chloride, 0.20g of potassium chloride, 0.43g of nickel chloride and 0.58g of ferric chloride, and then dried and calcined at 500℃ for 2 hours. After reduction at 500℃ for 2 hours under hydrogen atmosphere, a high-density long-chain alkane dehydrogenation catalyst with a component content of Pt0.4%, Sn0.8%, Ni1.0%, Fe1.0% and K0.5% was obtained, which was recorded as Cat-1.

[0035] Example 2

[0036] Preparation of high-density long-chain alkane dehydrogenation catalyst

[0037] 20g of high-density γ-Al2O3 was vacuum immersed in a 30mL mixed solution containing 0.35g of chloroplatinic acid, 0.30g of stannous chloride, 0.43g of nickel chloride and 0.58g of ferric chloride, and then dried and calcined at 500℃ for 2 hours. After cooling, it was further vacuum immersed in a 30mL aqueous solution containing 0.20g of potassium chloride, and then dried and calcined at 500℃ for 2 hours. After reduction at 500℃ for 2 hours under hydrogen atmosphere, a high-density long-chain alkane dehydrogenation catalyst with a component content of Pt0.4%, Sn0.8%, Ni1.0%, Fe1.0% and K0.5% was obtained, which was recorded as Cat-2.

[0038] Example 3

[0039] Preparation of high-density long-chain alkane dehydrogenation catalyst

[0040] 20g of high-density γ-Al2O3 was vacuum immersed in a 30mL mixed solution containing 0.35g of chloroplatinic acid and 0.30g of stannous chloride, dried, and calcined at 500℃ for 2 hours. After cooling, it was further vacuum immersed in a 30mL aqueous solution containing 0.20g of potassium chloride, 0.43g of nickel chloride and 0.58g of ferric chloride, dried, and calcined at 500℃ for 2 hours. After reduction at 500℃ for 2 hours under hydrogen atmosphere, a high-density long-chain alkane dehydrogenation catalyst with a component content of Pt0.4%, Sn0.8%, Ni1.0%, Fe1.0% and K0.5% was obtained, which was recorded as Cat-3.

[0041] Example 4

[0042] Preparation of high-density long-chain alkane dehydrogenation catalyst

[0043] 20g high-density γ-Al2O3 was vacuum immersed in a 30mL mixed solution containing 0.20g potassium chloride, 0.43g nickel chloride and 0.58g ferric chloride, dried and calcined at 500℃ for 2 hours. After cooling, it was further vacuum immersed in a 30mL aqueous solution containing 0.35g chloroplatinic acid and 0.30g stannous chloride, dried and calcined at 500℃ for 2 hours. After reduction at 500℃ for 2 hours under hydrogen atmosphere, a high-density long-chain alkane dehydrogenation catalyst with component contents of Pt0.4%, Sn0.8%, Ni1.0%, Fe1.0% and K0.5% was obtained, which was recorded as Cat-4.

[0044] Research test cases

[0045] Catalyst evaluation

[0046] 10mL of the catalysts Cat-1 to 4 prepared in Examples 1 to 4 were used for the long-chain alkane dehydrogenation life evaluation test. The test used C10 to C13 straight-chain alkanes that had been hydrofined as raw materials. The test selected more stringent reaction conditions to accelerate the deactivation of the catalyst so that the catalyst performance could be compared in a short time. The reaction temperature was 490°C, the reaction pressure was 0.14MPa, the alkane liquid hourly space velocity was 20h-1, and the hydrogen-to-hydrocarbon molar ratio was 6.0. The reaction results showed that the selectivity of all catalysts for converting alkanes to monoolefins was 90 to 92%, and the specific conversion rates are shown in Table 1.

[0047] Table 1 Conversion rate of long-chain alkane dehydrogenation catalyzed by Cat-1~4

[0048] catalyst Cat-1 Cat-2 Cat-3 Cat-4 463℃ initial activity 14.73 14.18 13.78 13.56 2h conversion rate of life acceleration experiment / % 29.20 27.92 27.84 26.67 4h conversion rate of life acceleration experiment / % 28.91 26.84 27.25 26.05 Life-prolonging experiment 6h conversion rate / % 28.42 26.40 26.64 25.54 8h conversion rate of life acceleration experiment / % 28.06 25.49 25.82 25.01 Life-prolonging experiment 10h conversion rate / % 27.83 25.01 25.19 24.66 Longevity test 12h conversion rate / % 27.46 24.24 24.75 24.11 Longevity test 14h conversion rate / % 27.41 23.93 24.12 23.85 Conversion rate decreased within 14 hours % 1.79 3.99 3.72 2.82 Average conversion rate % 28.18 27.00 25.94 25.13

[0049] Comparative Example 1

[0050] 20g of traditional macroporous γ-Al2O3 was vacuum impregnated in equal volumes in 30mL of a mixed solution containing 0.35g of chloroplatinic acid, 0.30g of stannous chloride, 0.20g of potassium chloride, 0.43g of nickel chloride and 0.58g of ferric chloride, dried and calcined at 500°C for 2 hours. After reduction at 500°C for 2 hours under a hydrogen atmosphere, a traditional long-chain alkane dehydrogenation catalyst with a component content of Pt0.4%, Sn0.8%, Ni 1.0%, Fe1.0% and K 0.5% was obtained, which was recorded as Cat-db1. The evaluation conditions for the catalyst's long-chain alkane dehydrogenation life are exactly the same as those in Example 5. The selectivity of the catalyst for converting alkanes to monoolefins is 91%, and the specific conversion rate is shown in Table 2.

[0051] Comparative Example 2

[0052] 20g of traditional macroporous γ-Al2O3 was vacuum impregnated in equal volumes in 30mL of a mixed solution containing 0.35g of chloroplatinic acid, 0.30g of stannous chloride, 0.43g of nickel chloride and 0.58g of ferric chloride, and then dried and calcined at 500℃ for 2 hours. After cooling, it was further vacuum impregnated in equal volumes in 30mL of an aqueous solution containing 0.20g of potassium chloride, and then dried and calcined at 500℃ for 2 hours. After reduction at 500℃ for 2 hours under a hydrogen atmosphere, a traditional long-chain alkane dehydrogenation catalyst with a component content of Pt0.4%, Sn0.8%, Ni 1.0%, Fe 1.0% and K0.5% was obtained, which was recorded as Cat-db2. The evaluation conditions for the catalyst's long-chain alkane dehydrogenation catalytic life are exactly the same as those in Example 5. The selectivity of the catalyst for converting alkanes to monoolefins is 91%, and the specific conversion rate is shown in Table 2.

[0053] Table 2 Conversion rate of long-chain alkane dehydrogenation catalyzed by Cat-db1~2

[0054] catalyst Cat-db1 Cat-db2 463℃ initial activity 13.50 13.60 2h conversion rate of life acceleration experiment / % 25.95 25.03 4h conversion rate of life acceleration experiment / % 25.57 24.47 Life-prolonging experiment 6h conversion rate / % 24.62 23.72 8h conversion rate of life acceleration experiment / % 23.90 23.43 Life-prolonging experiment 10h conversion rate / % 22.67 22.69 Longevity test 12h conversion rate / % 21.87 20.72 Longevity test 14h conversion rate / % 21.81 20.67 Conversion rate decreased within 14 hours % 4.14 4.36 Average conversion rate % 23.98 22.80

[0055] Comparing the long-chain alkane dehydrogenation reaction results in Table 1 and Table 2, it can be seen that compared with the dehydrogenation catalyst prepared by traditional macroporous alumina, the high-density long-chain alkane dehydrogenation catalyst prepared by the present invention has the advantages of higher activity and good stability. The technology of the high-density long-chain alkane dehydrogenation catalyst provided by the present invention has good application prospects.

[0056] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A high-density long-chain alkane dehydrogenation catalyst, characterized in that: A composition of Pt, Sn, Ni, Fe and alkali metals or their oxides supported on medium- and microporous alumina.

2. A high-density long-chain alkane dehydrogenation catalyst as claimed in claim 1, characterized in that: The component contents of the high-density long-chain alkane dehydrogenation catalyst are calculated by element mass, specifically 0.35-0.55% of Pt, 0.5-3.0% of Sn, 2.0-10.0% of Ni, 0.20-5.0% of Fe, and 0.20-2.0% of alkali metal.

3. A high-density long-chain alkane dehydrogenation catalyst as claimed in claim 2, characterized in that The total pore volume of the microporous alumina carrier is 0.8-2.5 mL / g, the bulk density is 0.3-0.6 g / mL, and the specific surface area is 100-300 m 2 / g.

4. A high-density long-chain alkane dehydrogenation catalyst as claimed in claim 3, characterized in that: The medium and microporous alumina carrier is a high-density medium and microporous alumina carrier.

5. The method for preparing a high-density long-chain alkane dehydrogenation catalyst according to any one of claims 1 to 4, characterized in that: The specific steps are as follows: (1) vacuum treating a high-density medium- and microporous alumina support for 0.5 to 1.0 h, then immersing it in an aqueous solution containing soluble salts of Pt, Sn, Ni, Fe and alkali metals, drying it in a 70-90° C. water bath for 0.5 to 1.0 h, drying it in an oven at 100 to 150° C. for 2 to 6 h, and finally calcining it in a muffle furnace at 500 to 540° C. for 4 to 8 h; obtaining product A; (2) washing the product A obtained in the above step (1) in a steam-air mixture at 500-540° C. for 2-6 hours to obtain product B; (3) The product B obtained above is reduced in pure hydrogen with a water content of less than 20 ppm at 460-550° C. for 4-8 hours to obtain a catalyst.

6. The method for preparing a high-density long-chain alkane dehydrogenation catalyst as claimed in claim 5, characterized in that: In step (1), the alkali metal supported on the catalyst is introduced as potassium chloride.

7. The method for preparing a high-density long-chain alkane dehydrogenation catalyst as claimed in claim 5, characterized in that: The purity of hydrogen in step (3) is >99.5%.

8. Use of the catalyst prepared by the preparation method according to claim 5 in the dehydrogenation process of long-chain normal alkanes to produce monoolefins.