Propane dehydrogenation propylene preparation supported catalyst treated in special atmosphere and preparation method thereof

Abstract

The invention discloses a catalyst for preparing propylene through propane dehydrogenation prepared by special atmosphere treatment and a preparation method of the catalyst. The catalyst is zCr2O3 / xMaOb.yAl2O3. M is one or more of Ba, Mg, La, Mn, Zr, K, Na, Ca, Zn, Ce, Bi, Fe, Nb and Sb, a is equal to 1-3, b is equal to 1-4, x is equal to 0-1, y is equal to 1-8, and z is equal to 10-30%. The catalyst is roasted for 2-10 hours in different atmospheres at the temperature of 500-1000 DEG C, the roasting atmospheres comprise one or more of H2, Ar gas, natural gas, propane, N2 gas and vacuum roasting (the vacuum degree is 0.1 atmospheric pressure), and the catalyst roasted in the different atmospheres shows different adsorption / desorption performance on propane and propylene within a certain temperature range (2000-600 DEG C). Therefore, the propane dehydrogenation performance and the carbon deposition resistance of the catalyst are obviously influenced.

Description

Technical Field

[0001] The invention relates to a propane dehydrogenation to propylene supported catalyst with special propane and propylene adsorption / desorption performance, high activity and high carbon deposition resistance and a preparation method thereof, belonging to the field of chemical industry. Background Art

[0002] Propylene is an important petrochemical raw material second only to ethylene, with a total domestic demand of 40 million tons per year. In recent years, the average annual growth rate of my country's propylene equivalent demand has reached 7.6%, exceeding the growth rate of propylene production capacity. With the rapid growth of demand for downstream products such as polypropylene, butylene octanol, acrylonitrile, propylene oxide, epichlorohydrin, acetone, and acrylic acid, the supply of propylene resources has gradually become tense, providing business opportunities for propane dehydrogenation projects, resulting in a very broad prospect for the PDH production process of propylene to expand the source of propylene in recent years. In particular, in recent years, with the breakthroughs in the development of unconventional natural resources such as shale gas in the world, it has become possible to obtain long-term, stable, and relatively low-cost propane resources, making the propane dehydrogenation (PDH) production process of propylene a hot topic of concern, with strong market competitiveness, and thus triggering industry giants to invest in one after another.

[0003] The activity and stability of the catalytic dehydrogenation reaction are related to the adsorption / desorption performance of the raw material propane and the product propylene on the catalyst surface. Higher propane adsorption capacity and higher propylene desorption capacity will greatly improve the propane dehydrogenation activity, selectivity and anti-carbon deposition performance. In view of this, the present invention develops a propane dehydrogenation to propylene catalyst treated with a special atmosphere, which has good propane adsorption and propylene desorption, thereby improving the propane conversion rate and propylene selectivity and extending the service life of the catalyst. Summary of the invention

[0004] The present invention provides a propane dehydrogenation to propylene supported catalyst with high activity, high selectivity and excellent carbon deposition resistance treated by special atmosphere and a preparation method thereof, that is, by adjusting the calcination process of the catalyst, a propane dehydrogenation to propylene Cr-based catalyst with good propane adsorption and propylene desorption is prepared. The propane dehydrogenation results of the catalyst show that the catalyst has excellent propane conversion rate, propylene selectivity and high carbon deposition resistance.

[0005] The present invention provides a method for preparing a supported catalyst for propane dehydrogenation to propylene with special atmosphere treatment, comprising the following steps:

[0006] (1) Preparation of metal-doped aluminum oxide salt xM by precipitation method a O b·yAl2O3 carrier powder material, wherein M = one or more of Ba, Mg, La, Mn, Zr, K, Na, Ca, Zn, Ce, Bi, Fe, Nb, Sb, a = 1 to 3, b = 1 to 4, x = 0 to 1, y = 1 to 8.

[0007] (2) With Cr2O3 as the active component, the above xM a O b ·yAl2O3 is used as the carrier material, and zCr2O3 / xM is prepared by impregnation method a O b yAl2O3 supported catalyst;

[0008] (3) zCr2O3 / xM prepared in step (2) a O b The yAl2O3 supported catalyst is calcined in a special atmosphere at 500-1000°C for 2-10 hours.

[0009] Based on the above technical solution, preferably, the roasting atmosphere includes one or more of H2, CO, Ar gas, natural gas, propane, N2 gas and vacuum roasting (vacuum degree 0.1 to 0.05 atmospheres).

[0010] Based on the above technical solution, preferably, the Cr2O3 active component precursor material is one or more of chromium nitrate, chromium acetate, chromium citrate, chromic anhydride, and chromium acetylacetonate.

[0011] Based on the above technical solution, preferably, the carrier powder material is subjected to extrusion molding using an extruder and then calcined in air at 500-900° C. for 2-10 hours to obtain a molded carrier material.

[0012] Another object of the present invention is to provide a propane dehydrogenation to propylene supported catalyst treated with a special atmosphere obtained by the above preparation method.

[0013] Another object of the present invention is to provide the use of the above-mentioned propane dehydrogenation to propylene supported catalyst treated with special atmosphere in propane and propylene adsorption / desorption test, the test conditions are: pressure range 5-60kPa, adsorption / desorption temperature 200-600°C, preferably 300°C.

[0014] Another object of the present invention is to provide the use of the above-mentioned propane dehydrogenation to propylene supported catalyst treated with special atmosphere in the direct dehydrogenation of propane to propylene reaction, the reaction conditions are: reaction pressure 40-60kPa, preferably 50kPa; reaction temperature 560-620°C, preferably 580°C; propane reaction space velocity 300-400ml·g -1 ·h -1 , preferably 320ml·g -1 ·h-1 .

[0015] Beneficial effects:

[0016] The catalyst provided by the present invention is used for the adsorption / desorption of propane and propylene and the direct dehydrogenation of propane to propylene. The supported catalyst treated with a special atmosphere prepared by the present invention exhibits excellent catalytic activity (propylene conversion rate of 44-51%) and propylene product selectivity (85-94%) and anti-carbon deposition performance (carbon deposition amount of 51-89 μg / 0.5g catalyst) in the direct dehydrogenation of alkanes to propylene.

[0017] The method provided by the invention has wide applicability, simplicity, low cost and good repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 These are the propane adsorption / desorption isotherms of the supported catalysts treated in different atmospheres (★, ●, ○, ■, ▲ and △ are respectively the supported catalysts treated in H2 / Ar mixed gas, natural gas, propane, vacuum, N2 and air).

[0019] Figure 2 These are the propylene adsorption / desorption isotherms of the supported catalysts treated in different atmospheres (★, ●, ○, ■, ▲ and △ are respectively the supported catalysts treated in H2 / Ar mixed gas, natural gas, propane, vacuum, N2 and air). DETAILED DESCRIPTION

[0020] The following examples will further illustrate the present invention, but are not intended to limit the invention.

[0021] Example 1

[0022] The BaO·6Al2O3 carrier was prepared by precipitation method. Barium nitrate and aluminum nitrate were weighed according to the atomic ratio of Ba:Al in the chemical formula and dissolved in deionized water. An excess amount of aqueous ammonium carbonate solution was added dropwise to form a milky white precipitate. The white powder was filtered, washed and dried to obtain a white powder. The white powder was extruded into a strip by an extruder and then calcined at 8800°C for 3 hours to obtain a molded carrier material.

[0023] The Cr2O3 loaded catalyst was synthesized by impregnation method, wherein the loading amount of Cr2O3 was 15wt%. 10ml of chromium acetate solution (3mol / L) was added dropwise into 10g of the shaped carrier material to obtain a 15wt% Cr2O3 / BaO·6Al2O3 loaded catalyst.

[0024] Example 2

[0025] The 15wt% Cr2O3 / BaO·6Al2O3 supported catalyst prepared in Example 1 was calcined at 600°C for 3 hours under vacuum conditions with a vacuum degree of 0.1 atmosphere to obtain a light blue supported catalyst.

[0026] Example 3

[0027] The 15 wt% Cr2O3 / BaO·6Al2O3 supported catalyst prepared in Example 1 was calcined at 600°C for 3 hours in a N2 atmosphere with a N2 flow rate of 100 ml / min to obtain a light green supported catalyst.

[0028] Example 4

[0029] The 15 wt% Cr2O3 / BaO·6Al2O3 supported catalyst prepared in Example 1 was calcined at 600°C for 3 hours in a 10% H2 / Ar mixed gas atmosphere with a H2 / Ar mixed gas flow rate of 100 ml / min to obtain a blue-green supported catalyst.

[0030] Example 5

[0031] The 15 wt% Cr2O3 / BaO·6Al2O3 supported catalyst prepared in Example 1 was calcined at 600°C for 3 hours in a propane atmosphere with a propane gas flow rate of 100 ml / min to obtain a blue-green supported catalyst.

[0032] Example 6

[0033] The 15 wt% Cr2O3 / BaO·6Al2O3 supported catalyst prepared in Example 1 was calcined at 600°C for 3 hours in a natural gas atmosphere with a natural gas flow rate of 100 ml / min to obtain a blue-green supported catalyst.

[0034] Example 7

[0035] The supported catalysts treated with different atmospheres prepared in Examples 1 to 6 were used for propane adsorption / desorption test. Weigh 2.0 g of catalyst, the test gas was pure propane, the adsorption / desorption pressure was 5 to 60 kPa, and the adsorption / desorption temperature was 300°C. The test results are shown in Figure 1 The supported catalyst treated with reducing gas exhibited higher propane adsorption / desorption performance, indicating that the catalyst may exhibit higher propane conversion in the direct dehydrogenation of propane to propylene.

[0036] Example 8

[0037] The supported catalysts treated with different atmospheres prepared in Examples 1 to 6 were used for propylene adsorption / desorption tests. Weigh 2.0 g of catalyst, the test gas was pure propylene, the adsorption / desorption pressure was 5 to 60 kPa, and the adsorption / desorption temperature was 300°C. The test results are shown in Figure 2The supported catalyst treated with reducing gas exhibited lower propylene adsorption / desorption performance, indicating that the catalyst may exhibit higher propylene selectivity and anti-carbon deposition performance in the direct dehydrogenation of propane to propylene.

[0038] Example 9

[0039] The supported catalysts treated with different atmospheres prepared in Examples 1 to 6 were used for direct dehydrogenation of propane to propylene. 10 g of catalyst was weighed, the reaction feed gas was pure propane, the reaction pressure was 50 kPa, the reaction temperature was 580°C, and the reaction space velocity was 320 ml·g -1 ·h -1 The reaction results are listed in Table 1. It is obvious that the supported catalyst treated in reducing atmosphere exhibits excellent propane conversion and propylene selectivity at 580 °C.

[0040] Example 10

[0041] The catalyst after the direct dehydrogenation of propane to propylene reaction in Example 9 was used for thermogravimetric testing to obtain the determination of the surface carbon content of the supported catalyst treated with different atmospheres in the propane dehydrogenation reaction. 0.5 g of the catalyst after the reaction was weighed, the temperature was 25-650° C., and the air flow rate was 30 ml / min. The reaction results are listed in Table 1.

[0042] Comparative Example 1

[0043] Preparation of conventional reference supported catalyst Cr2O3 / Al2O3: Using Al2O3 as a carrier, a supported Cr-based catalyst was prepared by impregnation method, the Cr-containing precursor was trivalent chromium acetate, and the active component loading was 15wt%. The supported catalyst was calcined at 600°C for 3h in a conventional air atmosphere to obtain a light green conventional supported catalyst.

[0044] Comparative Example 2

[0045] The conventional supported catalyst Cr2O3 / Al2O3 prepared in Comparative Example 1 was used for propane adsorption / desorption test. Weigh 2.0g of catalyst, the test gas is pure propane, the adsorption / desorption pressure is 5-60kPa, and the adsorption / desorption temperature is 300℃. The test results are shown in Figure 1 and Figure 2 .

[0046] Comparative Example 3

[0047] The conventional supported catalyst Cr2O3 / Al2O3 prepared in Comparative Example 1 was used for propylene adsorption / desorption test. Weigh 2.0g of catalyst, the test gas is pure propylene, the adsorption / desorption pressure is 5-60kPa, and the adsorption / desorption temperature is 300℃. The test results are shown in Figure 1 and Figure 2 .

[0048] Comparative Example 4

[0049] The conventional supported catalyst Cr2O3 / Al2O3 prepared in Comparative Example 1 was used for direct dehydrogenation of propane to propylene. 10 g of catalyst was weighed, the raw gas was pure propane, the reaction pressure was 50 kPa, the reaction temperature was 580 °C, and the reaction space velocity was 320 ml·g -1 ·h -1 The reaction results are listed in Table 1.

[0050] Table 1 Comparison of propane dehydrogenation performance of supported catalysts treated with different atmospheres

[0051]

Claims

1. A method for preparing a supported catalyst for propane dehydrogenation to propylene treated with a special atmosphere, characterized in that: The steps include: (1) Preparation of metal-doped aluminum oxide salt xM by precipitation method a O b yAl2O3 carrier material, wherein M = one or more of Ba, Mg, La, Mn, Zr, K, Na, Ca, Zn, Ce, Bi, Fe, Nb, Sb, a = 1 to 3, b = 1 to 4, x = 0 to 1, y = 1 to 8; (2) The carrier material obtained in step (1) is impregnated to prepare a supported catalyst, wherein the supported catalyst is composed of a Cr2O3 active component and a carrier material, and its chemical formula is: zCr2O3 / xM a O b yAl2O3, where the loading amount z = 10-30%, (3) calcining the supported catalyst prepared in step (2) in a special atmosphere at 500 to 1000°C for 2 to 10 hours to obtain a propane dehydrogenation to propylene catalyst; wherein the calcination atmosphere comprises one or more of H2, CO, Ar gas, natural gas, propane, N2 gas and vacuum calcination.

2. The preparation method according to claim 1, characterized in that: The Cr2O3 active component precursor material is one or more of chromium nitrate, chromium acetate, chromium citrate, chromic anhydride, and chromium acetylacetonate.

3. The preparation method according to claim 1, characterized in that: The vacuum degree of the vacuum calcination is 0.1 to 0.05 atmospheres.

4. The preparation method according to claim 1, characterized in that: The carrier material is extruded and molded, and then calcined in air at 500-900°C for 2-10 hours to obtain a molded carrier material.

5. The supported catalyst for preparing propylene by dehydrogenation of propane treated with a special atmosphere obtained by the preparation method according to any one of claims 1 to 4.

6. Use of the propane dehydrogenation to propylene supported catalyst treated with special atmosphere as claimed in claim 5 in the adsorption / desorption of propane and propylene.

7. The use according to claim 6, characterized in that: The adsorption-desorption conditions are: pressure 5-60 kPa, reaction temperature 200-600 oC.

8. Use of the propane dehydrogenation to propylene supported catalyst treated with special atmosphere as claimed in claim 5 in the direct dehydrogenation of propane to propylene reaction.

9. The use according to claim 8, characterized in that: The reaction conditions are: reaction pressure 40-60 kPa, reaction temperature 560-620 °C, propane reaction space velocity 300-400 ml·g -1 ·h -1 .

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