Gallium-based propane dehydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention provides a gallium-based propane dehydrogenation catalyst as well as a preparation method and application thereof, and relates to the field of petrochemical engineering catalysis. The catalyst comprises the following components in percentage by mass: 3-20% of gallium element, 1-10% of additive element and the balance of carrier element, wherein the carrier is zinc aluminate. The preparation method comprises the following steps: S1, preparing a zinc aluminate carrier, putting the zinc aluminate carrier in a negative pressure environment, and standing for 30-60 minutes; s2, uniformly mixing the gallium-containing solution and the assistant-containing solution to obtain an impregnation liquid; and S3, sucking the impregnation liquid into the surface of the zinc aluminate carrier under negative pressure, aging and drying, and roasting in a muffle furnace. The catalyst has relatively high propane dehydrogenation reaction performance and long-time stability, and has relatively high propylene selectivity and good stability when being applied to a propane dehydrogenation reaction process.

Description

Technical Field

[0001] The present invention relates to the field of petrochemical catalysis, and in particular to a gallium-based propane dehydrogenation catalyst, a preparation method and application thereof. Background Art

[0002] Propane anaerobic dehydrogenation (PDH) is one of the industrial processes for the targeted production of propylene. Compared with the traditional oil-to-propylene production route, this process has the advantages of high propylene selectivity, abundant raw material sources, simple product composition, and easy separation.

[0003] Cr-based catalysts are currently the most widely used dehydrogenation catalysts, but metal Cr is a heavy metal component that is easy to pollute the environment, and the reaction temperature is high, and there is a serious carbon deposition problem during the reaction. Pt-based catalysts have high reaction activity, high propylene selectivity, low toxicity, and are more environmentally friendly. However, Pt particles are prone to sintering and growing under high temperature conditions, and are also prone to carbon deposition and deactivation, and have poor stability, which greatly reduces the production capacity of the equipment. Therefore, the development of new non-precious metal catalysts that do not contain Cr species plays an important role in the production of propylene in actual industrial processes.

[0004] The Chinese patent (CN110614092A) uses S-modified Al2O3 as a carrier and Fe, Ni, Zn, Mo, W, Mn, Cu, and Sn as active components to prepare a dehydrogenation catalyst; however, during the propane dehydrogenation reaction, the catalyst deactivates rapidly. The best catalyst described in its specification has little change in selectivity after 6 hours of reaction, but the propane conversion rate decreases by 3%. It can be seen that the stability of the catalyst needs to be improved.

[0005] The Chinese patent (CN114425397A) uses prismatic molecular sieves as carriers and fourth period B group elements, VIB group elements, and VIA group elements as active components. Through the confinement effect of the molecular sieve, the mass transfer efficiency of the catalyst is improved, and the stability of the catalyst is improved to a certain extent, but its initial activity is low, with only 24% propane conversion rate at 550°C.

[0006] The Chinese patent (CN109939688B) uses gallium species as the active center and improves the stability of propane to a certain extent through the regulation of the auxiliary iron, but also sacrifices the conversion rate of propane.

[0007] The above catalysts all have poor stability and low conversion rate, making them difficult to use in industrial production. Summary of the invention

[0008] The object of the present invention is to provide a gallium-based propane dehydrogenation catalyst, which has high propane dehydrogenation reaction performance and long-term stability, and has high propylene selectivity and good stability during the propane dehydrogenation reaction process.

[0009] Another object of the present invention is to provide a method for preparing a gallium-based propane dehydrogenation catalyst, which is simple in preparation, has low requirements on equipment, and can be produced industrially.

[0010] The present invention solves the technical problem by adopting the following technical solutions.

[0011] On the one hand, an embodiment of the present invention provides a gallium-based propane dehydrogenation catalyst, which comprises, by mass percentage: 3-20% gallium element, 1-10% auxiliary element, and the remainder is a carrier element; wherein the carrier is zinc aluminate.

[0012] In some embodiments of the present invention, the auxiliary element is one or more of titanium, zirconium, indium, tin, germanium, niobium, and molybdenum.

[0013] In some embodiments of the present invention, the auxiliary element is derived from one or more of nitrate, chloride, oxide, and oxalate.

[0014] In some embodiments of the present invention, the gallium element is derived from one or more of gallium nitrate, gallium carbonate, metallic gallium, gallium oxide, and gallium halide.

[0015] In some embodiments of the present invention, the catalyst has a specific surface area of ​​30 to 100 m 2 / g, pore volume is 0.15~0.9cm 3 / g.

[0016] On the other hand, an embodiment of the present invention provides a method for preparing a gallium-based propane dehydrogenation catalyst, comprising the following steps:

[0017] S1, preparing a zinc aluminate carrier, placing the zinc aluminate carrier in a negative pressure environment and keeping it still for 30-60 minutes;

[0018] S2, mixing the gallium-containing solution and the additive-containing solution uniformly to obtain an impregnation solution;

[0019] S3, sucking the impregnation solution onto the surface of the zinc aluminate carrier under negative pressure, aging and drying, and then calcining in a muffle furnace.

[0020] In some embodiments of the present invention, the preparation of the zinc aluminate carrier comprises the following steps:

[0021] S11, hydrolyzing the organic alcohol aluminum salt, and then adding zinc salt to obtain a zinc-aluminum mixture;

[0022] S12, drying and calcining the zinc-aluminum mixture to obtain a zinc aluminate carrier precursor;

[0023] S13, uniformly mixing the obtained zinc aluminate carrier precursor, a binder and a pore expanding agent;

[0024] S14, extruding the mixture into a shape, drying, and calcining to obtain a zinc aluminate carrier.

[0025] In some embodiments of the present invention, the organic alcohol aluminum salt is one of aluminum isopropoxide and aluminum sec-butoxide, or a mixture of the two; the zinc salt is one or more of zinc nitrate, zinc chloride, zinc oxide, and zinc acetate.

[0026] In some embodiments of the present invention, the binder is one or more of nitric acid, hydrochloric acid, citric acid, methyl cellulose, cyclodextrin, starch, and sesbania powder.

[0027] In a third aspect, an embodiment of the present invention provides an application of a gallium-based propane dehydrogenation catalyst in propane dehydrogenation, wherein the pressure of the propane dehydrogenation is 0.01-0.5Mpa, the temperature is 530°C to 660°C, and the mass space velocity is 0.1-10h -1 .

[0028] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0029] The gallium-based propane dehydrogenation catalyst provided by the present invention does not contain Cr elements, has less harm to human body and environment, and does not contain precious metal elements, thus reducing the production cost of the catalyst. The catalyst uses zinc aluminate spinel as a carrier, which solves the problem of carbon deposition caused by excessive acidity of traditional alumina carriers. The introduction of auxiliary elements not only adjusts the existence state of the active components on the carrier, making the active components highly dispersed on the carrier surface, but also achieves the effect of transferring carbon deposits from active sites to the carrier surface during the dehydrogenation reaction. Based on these two advantages, the catalyst has higher propane dehydrogenation reaction performance and long-term stability. The catalyst is applied to the propane dehydrogenation reaction process and has higher propylene selectivity and good stability.

[0030] The catalyst preparation method provided by the invention is simple, the raw materials are readily available, the price is low, the catalyst is non-toxic, and the catalyst has industrialization potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 This is the catalyst preparation process of the embodiment of the present invention;

[0033] Figure 2 This is the preparation process of the zinc aluminate carrier in the embodiment of the present invention;

[0034] Figure 3 This is the stability performance diagram of the catalyst in Example 3. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to specific embodiments.

[0037] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0038] Example 1

[0039] The catalyst of this embodiment was prepared as follows:

[0040] Weigh 1020g of aluminum isopropoxide into a beaker, add 3L of deionized water, hydrolyze for 2h, add 610g of zinc acetate, continue stirring for 2h, heat to 100°C, evaporate the solvent, dry in an oven, and calcine at 600°C. Put the calcined sample into a kneader, add 30g of nitric acid, 6g of cyclodextrin, and 60g of deionized water, knead for 30min, extrude, dry, and calcine to obtain a strip-shaped zinc aluminate carrier.

[0041] Weigh 10g of the above-mentioned carrier and place it in a negative pressure environment for 30 minutes, which is recorded as A. Weigh 1g of gallium precursor solution gallium nitrate and add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under negative pressure conditions (vacuum pump), add solution B to A, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. The obtained dry product is placed in an oven at 80℃ for drying and calcined at 600℃ for 4h to obtain the catalyst Ga / ZnAl2O4. The specific surface area of ​​the catalyst is 34.95m 2 / g, pore volume is 0.19cm 3 / g.

[0042] Example 2

[0043] Weigh 1230g of aluminum sec-butoxide into a beaker, add 3L of deionized water, hydrolyze for 2h, add 202g of zinc oxide, continue stirring for 2h, heat to 100°C, evaporate the solvent, put it in an oven for drying, and roast it at 600°C. Put the roasted sample into a kneader, add 36g of nitric acid, 4.5g of starch, and 70g of deionized water, knead for 30min, extrude, dry, and roast to obtain a strip-shaped zinc aluminate carrier.

[0044] Weigh 10g of the above-mentioned carrier and let it stand under negative pressure for 30min, record it as A. Weigh 1g of gallium precursor solution gallium chloride and 0.3g of titanium precursor titanium oxide solution, add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under negative pressure conditions (vacuum pump), add solution B to A under negative pressure, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. Dry the obtained dry product in an oven at 80℃ and calcine at 600℃ for 4h to obtain the catalyst 10Ga-3Ti / ZnAl2O4. The specific surface area of ​​the catalyst is 35.04m 2 / g, pore volume is 0.24cm 3 / g.

[0045] Example 3

[0046] Weigh 1020g of aluminum isopropoxide into a beaker, add 3L of deionized water, hydrolyze for 2h, add 202g of zinc oxide, continue stirring for 2h, heat to 100°C, evaporate the solvent, dry in an oven, and calcine at 600°C. Put the calcined sample into a kneader, add 45g of nitric acid, 12g of glacial acetic acid, and 80g of deionized water, knead for 30min, extrude, dry, and calcine to obtain a strip-shaped zinc aluminate carrier.

[0047] Weigh 10g of the above-mentioned carrier and let it stand under negative pressure for 30 minutes, which is recorded as A. Weigh 1g of gallium precursor solution gallium chloride and 0.3g of tin precursor stannous chloride solution, add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under negative pressure conditions (vacuum pump), add solution B to A under negative pressure, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. The obtained dry product is placed in an oven at 80℃ for drying, and calcined at 600℃ for 4h to obtain the catalyst 10Ga-3Sn / ZnAl2O4. The specific surface area of ​​the catalyst is 36.90m 2 / g, pore volume is 0.21cm 3 / g.

[0048] Example 4

[0049] Weigh 1020g of aluminum isopropoxide into a beaker, add 3L of deionized water, hydrolyze for 2h, add 202g of zinc oxide, continue stirring for 2h, heat to 100°C, evaporate the solvent, dry in an oven, and calcine at 600°C. Put the calcined sample into a kneader, add 45g of nitric acid, 12g of glacial acetic acid, and 80g of deionized water, knead for 30min, extrude, dry, and calcine to obtain a strip-shaped zinc aluminate carrier.

[0050] Weigh 10g of the above-mentioned carrier and let it stand under negative pressure for 30 minutes, which is recorded as A. Weigh 1g of gallium precursor solution gallium chloride and 0.3g of zirconium precursor zirconium oxychloride solution, add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under negative pressure conditions (vacuum pump), add solution B to A under negative pressure, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. The obtained dry product is placed in an oven at 80℃ for drying, and calcined at 600℃ for 4h to obtain the catalyst 10Ga-3Zr / ZnAl2O4. The specific surface area of ​​the catalyst is 31.54m 2 / g, pore volume is 0.17cm 3 / g.

[0051] Example 5

[0052] Weigh 1020g of aluminum isopropoxide into a beaker, add 3L of deionized water, hydrolyze for 2h, add 408g of zinc acetate, continue stirring for 2h, heat to 100°C, evaporate the solvent, dry in an oven, and calcine at 600°C. Put the calcined sample into a kneader, weigh 7.32g of sesbania powder, 36.6g of nitric acid solution and 60g of deionized water into the kneader, knead for 20min, extrude, dry, and calcine to obtain a strip-shaped zinc aluminate carrier.

[0053] Weigh 10g of the above-mentioned carrier and let it stand under negative pressure for 30min, record it as A. Weigh 1g of gallium precursor solution gallium chloride and 0.3g of indium precursor indium nitrate solution, add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under negative pressure conditions (vacuum pump), add solution B to A under negative pressure, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. Dry the obtained dry product in an oven at 80℃ and calcine at 600℃ for 4h to obtain the catalyst 10Ga-3In / ZnAl2O4. The specific surface area of ​​the catalyst is 38.80m 2 / g, pore volume is 0.21cm 3 / g.

[0054] Example 6

[0055] Weigh 1020g of aluminum isopropoxide into a beaker, add 3L of deionized water, hydrolyze for 2h, add 610g of zinc acetate, continue stirring for 2h, heat to 100°C, evaporate the solvent, dry in an oven, and calcine at 600°C. Put the calcined sample into a kneader, add 30g of nitric acid, 6g of cyclodextrin, and 60g of deionized water, knead for 30min, extrude, dry, and calcine to obtain a strip-shaped zinc aluminate carrier.

[0056] Weigh 10g of the above-mentioned carrier and let it stand under negative pressure for 30min, record it as A. Weigh 1g of gallium precursor solution gallium chloride and 0.3g of germanium precursor germanium nitrate solution, add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under negative pressure conditions (vacuum pump), add solution B to A under negative pressure, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. Dry the obtained dry product in an oven at 80℃ and calcine at 600℃ for 4h to obtain the catalyst 10Ga-3Ge / ZnAl2O4. The specific surface area of ​​the catalyst is 36.60m 2 / g, pore volume is 0.20cm 3 / g.

[0057] Comparative Example 1

[0058] Weigh 10g of commercially formed carrier α-alumina and disperse it in 50ml of deionized water, stir at high speed for 30min to obtain mixed solution A. Weigh 1g of Ga precursor solution gallium nitrate and add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under the condition of high-speed stirring of mixed solution A, add solution B dropwise, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. The obtained dry product is placed in an oven at 80℃ for drying and calcined at 600℃ for 4h. The catalyst is recorded as 10Ga / Al2O3.

[0059] Comparative Example 2

[0060] 102 g of an aluminum oxide sample was weighed and put into a kneader, and 30 g of nitric acid, 6 g of cyclodextrin and 60 g of deionized water were added and kneaded for 30 minutes, and then extruded, dried and calcined.

[0061] Weigh 10g of the formed carrier and disperse it in 50ml of deionized water, stir at high speed for 30min to obtain mixed solution A. Weigh 1g of Ga precursor solution gallium nitrate and add 20ml of deionized water for ultrasonic dissolution to obtain solution B. Under the condition of high-speed stirring of mixed solution A, add solution B dropwise, mix evenly, stir at room temperature for 2h, and evaporate the solvent by rotary evaporation. The obtained dry product is placed in an oven at 80℃ for drying and calcined at 600℃ for 4h. The catalyst is recorded as Ga / Al2O3.

[0062] Experimental example

[0063] 1. Propane dehydrogenation test

[0064] The process flow of propane dehydrogenation is the existing process flow, and the control parameters in the specific process flow are as follows: propane space velocity is 1h -1 , introduce an appropriate amount of nitrogen, maintain the propane partial pressure at 50kPa, and the total pressure of the reaction system is atmospheric pressure; the bed temperature is 550-580°C. Among them, the sample test was started 30 minutes after the propane was introduced. The catalyst compositions and test results of each embodiment and comparative example are shown in Table 1, and the propane conversion rate and propylene selectivity are calculated as follows:

[0065] The conversion rate of propane and the selectivity of propylene are calculated by normalization method:

[0066] Ai=Fr*C n *Aˋi;

[0067] Ai: corrected peak area; C n : carbon number; Aˋi: true peak area; Fr: relative molar corrected molecule;

[0068] Propane conversion % = ΣAi / (ΣAi+propane in A product)*100%;

[0069] Propylene selectivity % = Ai / ΣAi*100%;

[0070] Propylene yield % = conversion * selectivity * 100%.

[0071] Table 1 Catalyst compositions and experimental results of examples and comparative examples

[0072]

[0073]

[0074] It can be concluded from Table 1 above that the catalyst provided in Examples 2-6, whose carrier is zinc aluminate, whose active ingredient is Ga, and whose auxiliary element is added, has a higher conversion rate and selectivity in the propane dehydrogenation reaction; compared with Comparative Examples 1 and 2, which use alumina as a carrier and Ga as an active ingredient, the conversion rate and selectivity of the propane dehydrogenation reaction catalyzed by the catalyst are lower. In Example 1, no auxiliary element is added, and its conversion rate is lower than that of Examples 2-6, but higher than that of Comparative Examples 1-2. It can be seen that the addition of auxiliary elements can adjust the existence state of the active component on the carrier, so that the active component is highly dispersed on the surface of the carrier, and can also transfer the carbon deposits from the active site to the surface of the carrier during the dehydrogenation reaction, thereby improving the catalytic efficiency, and the conversion efficiency of the dehydrogenation reaction is high.

[0075] In Example 1, the catalyst without the introduction of the auxiliary element has a lower conversion rate, but the highest selectivity, because there are more propylene products and most of the propane is converted into propylene; while in other examples, after the introduction of the auxiliary element, the propane conversion rate is greatly improved, the propylene yield is also improved, and the by-products also increase to a certain extent.

[0076] 2. Catalyst stability test

[0077] The selectivity and conversion rate of the catalyst of Example 3 were tested at different time periods. The results are as follows: Figure 3 As shown, from Figure 3 It can be seen that the catalyst of Example 3 still has a high selectivity and conversion rate after being used for 1000 min, and the catalytic efficiency has not decreased significantly, indicating that the performance of the catalyst is stable.

[0078] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A gallium-based propane dehydrogenation catalyst, characterized in that: The percentage by mass includes: Gallium element 3-20%, auxiliary element 1-10%, and the balance are carrier elements; wherein the carrier is zinc aluminate.

2. The gallium-based propane dehydrogenation catalyst according to claim 1, characterized in that The auxiliary element is one or more of titanium, zirconium, indium, tin, germanium, niobium and molybdenum.

3. The gallium-based propane dehydrogenation catalyst according to claim 1, characterized in that The auxiliary element is derived from one or more of nitrate, chloride, oxide and oxalate.

4. The gallium-based propane dehydrogenation catalyst according to claim 1, characterized in that The gallium element is derived from one or more of gallium nitrate, gallium carbonate, metallic gallium, gallium oxide, and gallium halide.

5. The gallium-based propane dehydrogenation catalyst according to claim 1, characterized in that The specific surface area of ​​the catalyst is 30 to 100 m 2 / g, pore volume is 0.15~0.9cm 3 / g.

6. A method for preparing a gallium-based propane dehydrogenation catalyst according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, preparing a zinc aluminate carrier, placing the zinc aluminate carrier in a negative pressure environment and keeping it still for 30-60 minutes; S2, mixing the gallium-containing solution and the additive-containing solution uniformly to obtain an impregnation solution; S3, sucking the impregnation solution onto the surface of the zinc aluminate carrier under negative pressure, aging and drying, and then calcining in a muffle furnace.

7. The method for preparing a gallium-based propane dehydrogenation catalyst according to claim 6, characterized in that: The preparation of the zinc aluminate carrier comprises the following steps: S11, hydrolyzing the organic alcohol aluminum salt, and then adding zinc salt to obtain a zinc-aluminum mixture; S12, drying and calcining the zinc-aluminum mixture to obtain a zinc aluminate carrier precursor; S13, uniformly mixing the obtained zinc aluminate carrier precursor, a binder and a pore expanding agent; S14, extruding the mixture into a shape, drying, and calcining to obtain a zinc aluminate carrier.

8. The method for preparing a gallium-based propane dehydrogenation catalyst according to claim 7, characterized in that: The organic alcohol aluminum salt is one of aluminum isopropoxide and aluminum sec-butoxide or a mixture of the two; the zinc salt is one or more of zinc nitrate, zinc chloride, zinc oxide and zinc acetate.

9. The method for preparing a gallium-based propane dehydrogenation catalyst according to claim 7, characterized in that: The binder is one or more of nitric acid, hydrochloric acid, citric acid, methyl cellulose, cyclodextrin, starch, and sesbania powder.

10. Use of the gallium-based propane dehydrogenation catalyst according to any one of claims 1 to 5 in propane dehydrogenation, characterized in that: The propane dehydrogenation pressure is 0.01-0.5Mpa, the temperature is 530°C-660°C, and the mass space velocity is 0.1-10h -1 .

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