A catalyst for propane dehydrogenation to propylene and its preparation method and application

Abstract

The invention discloses a catalyst for propane dehydrogenation to propylene and a preparation method and application thereof. The catalyst comprises a support, an active component and promoters supported on the carrier. Among them, the carrier is alumina ball, the active component is platinum group metal, the promoters include three kinds: rare earth elements (Y, La, Ce, Pr, Nd), tin, and alkali metal elements (Li, Na, K). When the catalyst is used for propane dehydrogenation to propylene, higher propane conversion and propylene selectivity are obtained.

Claims

1. A catalyst for propane dehydrogenation to propylene, the catalyst includes a support, an active component and a promoter supported on the support. The catalyst is characterized in that the support is an alumina ball, the active component is platinum group metals, and the promoter includes rare earth elements of the first promoter, tin of the second promoter and alkali metal elements of the third promoter.

2. The catalyst for dehydrogenation of propane to propylene according to claim 1, which is characterized in that the active component is Pt, the rare earth elements of the first promoter are Y, La, Ce, Pr or Nd; and the alkali metal element of the third promoter is one of Li, Na and K.

3. The catalyst for dehydrogenation of propane to propylene according to claim 1, which is characterized in that the mass fraction of the carrier is 80%˜99.6%, the mass fraction of the active component Pt is 0.1%˜5%, the mass fraction of rare earth elements in the first promoter is 0.1%˜5%, the mass fraction of Sn in the second promoter is 0.1%˜5%, and the mass fraction of alkali metal element in the third promoter is 0.1%˜5%.

4. The preparation method of a catalyst for propane dehydrogenation to propylene according to claim 1, which is characterized in that it comprises the following contents: 1) Pt precursor and Sn precursor are dissolved in water to form a mixed solution, and then competitive agent is added to obtain impregnation solution A; 2) The alumina ball carrier is impregnated with the impregnation solution A, and then dried and calcined; 3) The rare earth metal precursor and K precursor are dissolved in water to form a mixed solution which is impregnation solution B; 4) The carrier calcined in step 2) is impregnated with the impregnation solution B. After the impregnation is finished, the obtained catalyst is dried and calcined to obtain propane dehydrogenation catalyst.

5. The preparation method of a catalyst for propane dehydrogenation to propylene according to claim 4, which is characterized in that the Pt precursor is chloroplatinic acid and the Sn precursor is SnCl.sub.2.

6. The preparation method of a catalyst for propane dehydrogenation to propylene according to claim 4, which is characterized in that the competitive adsorption agent is one or more of inorganic acid or organic acid, and the amount of competitive adsorption agent is 7-9% of the mass of impregnation solution A.

7. The preparation method of a catalyst for propane dehydrogenation to propylene according to claim 4, which is characterized in that the rare earth metal precursor is a soluble salt of rare earth metal elements.

8. The preparation method of a catalyst for propane dehydrogenation to propylene according to claim 4, which is characterized in that the K precursor is soluble potassium salt.

9. The preparation method of a catalyst for propane dehydrogenation to propylene according to claim 4, which is characterized in that in steps 2) and 4), the drying adopts vacuum drying, the drying temperature is 80-120° C., and the drying time is 6-10 h; the calcination temperature is 550-650° C., and the calcination time is 3-5 h.

10. The application of a catalyst for propane dehydrogenation to propylene according to claim 1, which is characterized in that propane dehydrogenation test is carried out in a quartz tube fixed bed reactor, the dehydrogenation reaction temperature is 550-650° C., the mass space velocity is 1 h.sup.−1-5 h.sup.−1, and the hydrogen/propane flow ratio is 1/4-1/1.

Description

EMBODIMENT

[0039] In order to make the purpose, the technical scheme and the advantages of the invention clearer, the present invention is further described in detail in combination with the embodiment. The schematic implementation and description of the invention are only used to explain the invention, not as the limitation of the invention.

EXAMPLE 1

[0040] In this embodiment, Catalyst 1, Pt—Sn—K—Y/Al.sub.2O.sub.3 is prepared, and its catalytic performance for propane dehydrogenation to propylene is tested.

[0041] Preparation: 1) prepare 0.02 g/g H.sub.2PtCl.sub.6.6H.sub.2O aqueous solution and 0.04 g/g SnCl.sub.2.2H.sub.2O aqueous solution.

[0042] Take 4.075 g and 0.729 g H.sub.2PtCl.sub.6.6H.sub.2O solution and SnCl.sub.2.2H.sub.2O solution respectively and put into a glass beaker, then add concentrated hydrochloric acid and deionized water, so that the volume of Pt—Sn impregnation solution is equal to the total volume of water absorbed by 10 g Al.sub.2O.sub.3 carrier, and the mass of concentrated hydrochloric acid is 8.3% of the mass of impregnation solution. After stirring evenly, impregnate 10 g alumina ball carrier with the solution. After soaking for 4 h, vacuum drying at 100° C. for 8 h and then calcine at 600° C. for 4 h;

[0043] 2) Prepare KNO.sub.3 aqueous solution with mass concentration of 0.07 g/g and YCl.sub.3 aqueous solution with mass concentration of 0.312 g/g respectively.

[0044] Take 3.023 g and 0.722 g KNO.sub.3 solution and YCl.sub.3 solution and put into a glass beaker and then add deionized water to make the volume of K—Y impregnation solution equal to the total volume of water absorption capacity of 10 g Al.sub.2O.sub.3 carrier. After stirring evenly, the alumina ball carrier calcined in step 1) is impregnated with the K—Y impregnation solution. The final Pt—Sn—K—Y/Al.sub.2O.sub.3 catalyst for propane dehydrogenation is then obtained by impregnation for 4 h, vacuum drying at 100° C. for 8 h and calcination at 600° C. for 4h.

[0045] Catalyst evaluation: a quartz tube fixed bed reactor was filled with 3 g Catalyst 1, the total mass space velocity of hydrogen and propane was controlled at 3 h.sup.−1, the hydrogen/propane flow ratio was 1/4, the reaction pressure was atmospheric pressure, the bed temperature was 610° C., and the reaction products were analyzed by using Shimadzu GC-2014C gas chromatography.

EXAMPLE 2

[0046] In this embodiment, Catalyst 2, Pt—Sn—K—La/Al.sub.2O.sub.3 is prepared, and its catalytic performance for propane dehydrogenation to propylene is tested.

[0047] Preparation: 1) prepare 0.02 g/g H.sub.2PtCl.sub.6.6H.sub.2O aqueous solution and 0.04 g/g SnCl.sub.2.2H.sub.2O aqueous solution.

[0048] Take 4.075 g and 0.729 g H.sub.2PtCl.sub.6.6H.sub.2O solution and SnCl.sub.2.2H.sub.2O solution respectively and put into a glass beaker, then add concentrated hydrochloric acid and deionized water, so that the volume of Pt—Sn impregnation solution is equal to the total volume of water adsorbed by 10 g Al.sub.2O.sub.3 carrier, and the mass of concentrated hydrochloric acid is 8.3% of the mass of impregnation solution. After stirring evenly, impregnate 10 g alumina ball carrier with this solution. Then soaking for 4 h, vacuum drying at 100° C. for 8 h and calcining at 600° C. for 4 h;

[0049] 2) Prepare KNO.sub.3 aqueous solution with mass concentration of 0.07 g/g and LaCl.sub.3 aqueous solution with mass concentration of 0.271 g/g respectively.

[0050] Take 3.023 g and 0.667 g KNO.sub.3 solution and LaCl.sub.3 solution respectively and put into a glass beaker, and then add deionized water to make the volume of K—La impregnation solution equal to the total volume of water absorption capacity of 10 g Al.sub.2O.sub.3 carrier. After stirring evenly, the alumina ball carrier calcined in step 1) is impregnated with this solution. The final Pt—Sn—K—La/Al.sub.2O.sub.3 catalyst for propane dehydrogenation is obtained by impregnation for 4 h, vacuum drying at 100° C. for 8 h and calcination at 600° C. for 4 h.

[0051] Catalyst evaluation: a quartz tube fixed bed reactor was filled with 3 g Catalyst 2, the total mass space velocity of hydrogen and propane was controlled to be 3 h.sup.−1, the hydrogen/propane flow ratio was 1/4, the reaction pressure was atmospheric pressure, the bed temperature was 610° C., and the reaction products were analyzed by using Shimadzu GC-2014C gas chromatography.

EXAMPLE 3

[0052] In this embodiment, Catalyst 3, Pt—Sn—K—Ce/Al.sub.2O.sub.3 is prepared, and its catalytic performance for propane dehydrogenation to propylene is tested.

[0053] Preparation: 1) prepare 0.02 g/g H.sub.2PtCl.sub.6.6H.sub.2O aqueous solution and 0.04 g/g SnCl.sub.2.2H.sub.2O aqueous solution. Take 4.075 g and 0.729 g H.sub.2PtCl.sub.6.6H.sub.2O solution and SnCl.sub.2.2H.sub.2O solution respectively and put into a glass beaker, then add concentrated hydrochloric acid and deionized water, so that the volume of Pt—Sn impregnation solution is equal to the total volume of water absorbed by 10 g Al.sub.2O.sub.3 carrier, and the mass of concentrated hydrochloric acid is 8.3% of the mass of impregnation solution. After stirring evenly, impregnate 10 g alumina ball carrier with this solution. Then soaking for 4 h, vacuum drying at 100° C. for 8 h and calcining at 600° C. for 4 h;

[0054] 2) Prepare KNO.sub.3 aqueous solution with mass concentration of 0.07 g/g and Ce(NO.sub.3).sub.3.6H.sub.2O aqueous solution with mass concentration of 0.2 g/g respectively.

[0055] Take 3.023 g and 1.585 g KNO.sub.3 solution and Ce(NO.sub.3).sub.3.6H.sub.2O solution respectively and put into a glass beaker, and then add deionized water to make the volume of K—Ce impregnation solution equal to the total volume of water absorption capacity of 10 g Al.sub.2O.sub.3 carrier. After stirring evenly, the alumina ball carrier calcined in step 1) is impregnated with this solution. The final Pt—Sn—K—Ce/Al.sub.2O.sub.3 catalyst for propane dehydrogenation was obtained by impregnation for 4 h, vacuum drying at 100° C. for 8 h and calcination at 600° C. for 4 h.

[0056] Catalyst evaluation: a quartz tube fixed bed reactor was filled with 3 g Catalyst 3, the total mass space velocity of hydrogen and propane was controlled to be 3 h.sup.−1, the hydrogen/propane flow ratio was 1/4, the reaction pressure was atmospheric pressure, the bed temperature was 610° C., and the reaction products were analyzed by using Shimadzu GC-2014C gas chromatography.

EXAMPLE 4

[0057] In this embodiment, Catalyst 4, Pt—Sn—K—Pr/Al.sub.2O.sub.3 is prepared, and its catalytic performance for propane dehydrogenation to propylene is tested.

[0058] Preparation: 1) prepare 0.02 g/g H.sub.2PtCl.sub.6.6H.sub.2O aqueous solution and 0.04 g/g SnCl.sub.2.2H.sub.2O aqueous solution.

[0059] Take 4.075 g and 0.729 g H.sub.2PtCl.sub.6.6H.sub.2O solution and SnCl.sub.2.2H.sub.2O solution respectively and put into a glass beaker, then add concentrated hydrochloric acid and deionized water, so that the volume of Pt—Sn impregnation solution is equal to the total volume of water absorbed by 10 g Al.sub.2O.sub.3 carrier, and the mass of concentrated hydrochloric acid is 8.3% of the mass of impregnation solution. After stirring evenly, impregnate 10 g alumina ball carrier with this solution. Then soaking for 4 h, vacuum drying at 100° C. for 8 h and calcining at 600° C. for 4 h;

[0060] 2) Prepare KNO.sub.3 aqueous solution with mass concentration of 0.07 g/g and Pr(NO.sub.3).sub.3.6H.sub.2O aqueous solution with mass concentration of 0.2 g/g respectively.

[0061] Take the KNO.sub.3 solution and Pr(NO.sub.3).sub.3.6H.sub.2O solution 3.023 g and 1.579 g respectively, then add deionized water to make the volume of K—Pr impregnation solution equal to the total volume of water absorption capacity of 10 g Al.sub.2O.sub.3 carrier. After stirring evenly, the alumina ball carrier calcined in step 1) is impregnated with this solution. The final Pt—Sn—K—Pr/Al.sub.2O.sub.3 catalyst for propane dehydrogenation was obtained by impregnation for 4h, vacuum drying at 100° C. for 8h and calcination at 600° C. for 4h.

[0062] Catalyst evaluation: a quartz tube fixed bed reactor was filled with 3 g Catalyst 4, the total mass space velocity of hydrogen and propane was controlled to be 3 h.sup.−1, the hydrogen/propane flow ratio was 1/4, the reaction pressure was atmospheric pressure, the bed temperature was 610° C., and the reaction products were analyzed by using Shimadzu GC-2014C gas chromatography.

EXAMPLE 5

[0063] In this embodiment, Catalyst 4, Pt—Sn—K—Nd/Al.sub.2O.sub.3 is prepared, and its catalytic performance for propane dehydrogenation to propylene is tested.

[0064] Preparation: 1) prepare 0.02 g/g H.sub.2PtCl.sub.6.6H.sub.2O aqueous solution and 0.04 g/g SnCl.sub.2.2H.sub.2O aqueous solution.

[0065] Take 4.075 g and 0.729 g H.sub.2PtCl.sub.6.6H.sub.2O solution and SnCl.sub.2.2H.sub.2O solution respectively and put into a glass beaker, then add concentrated hydrochloric acid and deionized water, so that the volume of Pt—Sn impregnation solution is equal to the total volume of water absorbed by 10 g Al.sub.2O.sub.3 carrier, and the mass of concentrated hydrochloric acid is 8.3% of the mass of impregnation solution. After stirring evenly, impregnate 10 g alumina ball carrier with this solution. Then soaking for 4 h, vacuum drying at 100° C. for 8 h and calcining at 600° C. for 4 h;

[0066] 2) Prepare KNO.sub.3 aqueous solution with mass concentration of 0.07 g/g and Nd(NO.sub.3).sub.3.6H.sub.2O aqueous solution with mass concentration of 0.2 g/g.

[0067] Take 3.023 g and 1.555 g of KNO.sub.3 solution and Nd(NO.sub.3).sub.3.6H.sub.2O solution and put into a glass beaker, and then add deionized water to make the volume of K—Pr impregnation solution equal to the total volume of water absorption capacity of 10 g Al.sub.2O.sub.3 carrier. After stirring evenly, the alumina ball carrier calcined in step 1) is impregnated with this solution. The final Pt—Sn—K—Nd/Al.sub.2O.sub.3 catalyst for propane dehydrogenation was obtained by impregnation for 4 h, vacuum drying at 100° C. for 8 h and calcination at 600° C. for 4 h.

[0068] Catalyst evaluation: a quartz tube fixed bed reactor was filled with 3 g Catalyst 5, the total mass space velocity of hydrogen and propane was controlled to be 3 h.sup.−1, the hydrogen/propane flow ratio was 1/4, the reaction pressure was atmospheric pressure, the bed temperature was 610° C., and the reaction products were analyzed by using Shimadzu GC-2014C gas chromatography.

Comparative Example 1

[0069] In this comparative embodiment, Catalyst 6, Pt—Sn—K/Al.sub.2O.sub.3 is prepared, and its catalytic performance for propane dehydrogenation to propylene is tested. The catalyst does not contain any rare earth elements as the first promoter.

[0070] Preparation: 1) prepare 0.02 g/g H.sub.2PtCl.sub.6.6H.sub.2O aqueous solution and 0.04 g/g SnCl.sub.2.2H.sub.2O aqueous solution.

[0071] Take 4.075 g and 0.729 g H.sub.2PtCl.sub.6.6H.sub.2O solution and SnCl.sub.2.2H.sub.2O solution respectively and put into a glass beaker, then add concentrated hydrochloric acid and deionized water, so that the volume of Pt—Sn impregnation solution is equal to the total volume of water adsorbed by 10 g Al.sub.2O.sub.3 carrier, and the mass of concentrated hydrochloric acid is 8.3% of the mass of impregnation solution. After stirring evenly, impregnate 10 g alumina ball carrier with this solution. Then soaking for 4 h, vacuum drying at 100° C. for 8 h and calcining at 600° C. for 4 h;

[0072] 2) Prepare KNO.sub.3 aqueous solution with mass concentration of 0.07 g/g.

[0073] Take 3.023 g KNO.sub.3 solution and put into a glass beaker, and then add deionized water to make the volume of K impregnation solution equal to the total volume of water absorption capacity of 10 g Al.sub.2O.sub.3 carrier. After stirring thoroughly, the alumina ball carrier calcined in step 1) is impregnated with this solution. The final Pt—Sn—K/Al.sub.2O.sub.3 catalyst for propane dehydrogenation was obtained by impregnation for 4 h, vacuum drying at 100° C. for 8 h and calcination at 600° C. for 4 h.

[0074] Catalyst evaluation: a quartz tube fixed bed reactor was filled with 3 g Catalyst 6, the total mass space velocity of hydrogen and propane was controlled to be 3 h.sup.−1, the hydrogen/propane flow ratio was 1/4, the reaction pressure was atmospheric pressure, the bed temperature was 610° C., and the reaction products were analyzed by using Shimadzu GC-2014C gas chromatography.

[0075] The content of active components and promoters of Catalysts 1-6 is shown in Table 1; The testing results of catalytic performance of the catalysts prepared by examples 1-5 and comparative example 1 are given in Table 2.

TABLE-US-00001 TABLE 1 Content of active component and promoters in the catalysts Component Mass Fractions (%) Pt Sn K Y La Ce Pr Nd Catalyst 1 0.3 0.15 0.8 1.0 — — — — Catalyst 2 0.3 0.15 0.8 — 1.0 — — — Catalyst 3 0.3 0.15 0.8 — — 1.0 — — Catalyst 4 0.3 0.15 0.8 — — — 1.0 Catalyst 5 0.3 0.15 0.8 — — — — 1.0 Catalyst 6 0.3 0.15 0.8 — — — — —

TABLE-US-00002 TABLE 2 Catalyst catalytic performance Initial catalyst performance (%) 3 h average Performance (%) Propane Propylene Propylene Propane Propylene Propylene No. Catalyst Conv. (%) Select. (%) Yield (%) Conv. (%) Select. (%) Yield (%) Example 1 Pt—Sn—K—Y/Al.sub.2O.sub.3 58.10 74.15 43.08 44.18 83.04 36.62 Example 2 Pt—Sn—K—La/Al.sub.2O.sub.3 56.17 75.63 42.49 37.18 81.15 30.15 Example 3 Pt—Sn—K—Ce/Al.sub.2O.sub.3 38.89 74.67 29.04 24.64 72.75 17.99 Example 4 Pt—Sn—K—Pr/Al.sub.2O.sub.3 50.96 75.97 38.72 28.18 75.95 21.49 Example 5 Pt—Sn—K—Nd/Al.sub.2O.sub.3 Comparative Pt—Sn—K/Al.sub.2O.sub.3 47.54 86.51 41.12 35.75 81.18 29.09 example 1

[0076] Combined with the evaluation results in Tables 1 and 2, it is shown that the performance of Pt—Sn based propane dehydrogenation catalyst can be modified by adding rare earth metal elements. Compared with comparative example 1, Y can significantly improve the catalytic performance and stability of Pt—Sn based propane dehydrogenation catalyst, while La can only play a slightly improving role. Ce and Pr decrease the catalytic performance and stability of Pt—Sn based catalysts.

[0077] The above-mentioned specific implementation examples further describe the purpose, technical scheme and beneficial effect of the invention. It should be understood that the above-mentioned is only the specific implementation examples of the invention, and is not used to limit the protection scope of the invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the invention.