A low-carbon alkane catalyst, a preparation method and application thereof

Abstract

This disclosure relates to a low-carbon alkane catalyst, its preparation method, and its application. The catalyst includes an alumina support and an active component and an auxiliary component supported on the alumina support. The active component includes chromium oxide, and the auxiliary component includes an oxide containing a first metal element and an oxide containing a second metal element. The first metal element includes one or more elements from Group IIIA and / or Group IVB; the second metal element includes any two or more elements from Group VIII, Group IB, Group IIB, Group IIIB, and Group VIIB. The catalyst of this disclosure incorporates specific metal elements, controls the ratio of chromium atoms to the first metal element and the second metal element in the catalyst to be 1:(0.05~2):(0.05~2), and controls the calcination temperature during the preparation process to be between 780 and 1000 °C. o C, to achieve the Cr species in chromium oxides in the catalyst. 3+ Cr 6+ The peak area ratio is 0.6~9, which improves the catalyst activity and the yield of dehydrogenation of low-carbon alkanes to olefins.

Description

Technical Field

[0001] This disclosure relates to the fields of petroleum refining and fine chemicals, and specifically to a low-carbon alkane catalyst, its preparation method, and its application. Background Technology

[0002] Low-carbon olefins are key raw materials for the manufacture of many chemicals. Taking propane as an example, it is not only an important feedstock for the production of propylene oxide, polypropylene, and acrylonitrile, but the growth of its downstream products is also continuously driving up the demand for propylene. Especially in recent years, with the advancement of shale gas development technology, the feedstock cost of propane has significantly decreased, making the production of olefins through dehydrogenation processes more commercially attractive. Dehydrogenation reactions can be divided into oxidizing and non-oxidizing types. Although oxidizing dehydrogenation has the advantage of producing less coke, in practical applications, the degree of alkane oxidation is difficult to control, which not only brings serious safety hazards but also inevitably leads to a reduction in olefin yield. Therefore, non-oxidizing alkane dehydrogenation (PDH) processes are widely used in industrial production.

[0003] Alumina-supported chromium (Cr) oxide catalysts are among the most common catalysts in industrial propane dehydrogenation (PDH) processes. However, side reactions on the alumina surface can reduce propylene selectivity and accelerate catalyst deactivation. Therefore, developing higher-performance Cr-based alkane dehydrogenation catalysts is currently a hot research topic. In propane dehydrogenation (PDH), the catalytic mechanism of oxide catalysts is based on organometallic chemistry principles. In the catalyst, the coordinatingly unsaturated Cr... 3+ -O pairs are considered to be active sites for highly efficient catalytic dehydrogenation reactions, and these unsaturated Cr... 3+ The formation of -O sites is closely related to the coordination environment of chromium ions. Constructing suitable unsaturated Cr... 3+ The coordination environment of the -O site is an effective strategy for preparing high-performance catalysts. Current research focuses on adding a second active metal such as tungsten (W) or vanadium (V), and co-activating components such as iron (Fe) or zirconium (Zr) to enhance the oxidation state of Cr. 3+ While the proportion of species is well studied, research on the regulation of Cr species coordination environment is still relatively limited.

[0004] Existing Cr-based catalysts for the dehydrogenation of low-carbon alkanes still have limitations, mainly manifested in low catalyst activity and insufficient olefin yield. Summary of the Invention

[0005] The purpose of this disclosure is to provide a low-carbon alkane catalyst, its preparation method, and its application. This catalyst has high activity and can improve the yield of low-carbon alkane dehydrogenation to olefins.

[0006] To achieve the above objectives, a first aspect of this disclosure provides a low-carbon alkane catalyst, the catalyst comprising an alumina support and an active component and an auxiliary component supported on the alumina support, the active component comprising chromium oxide, and the auxiliary component comprising an oxide containing a first metal element and an oxide containing a second metal element, the first metal element comprising one or more elements from Group IIIA and / or Group IVB; the second metal element comprising any two or more elements from Group VIII, Group IB, Group IIB, Group IIIB, and Group VIIB.

[0007] Optionally, based on the weight of the catalyst, the content of the alumina support is 50-99.4% by weight, preferably 55-90% by weight, the content of the active component is 0.5-20% by weight, preferably 4-15% by weight, and the total content of the auxiliary components is 0.1-30% by weight, preferably 6-30% by weight.

[0008] Optionally, the molar ratio of chromium to any first metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2); the molar ratio of chromium to any second metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2). Preferably, the Group IIIA element includes Ga; the Group IVB element includes Ti; the Group VIII element includes Co and / or Ni; the Group IB element includes Cu; the Group IIB element includes Zn; the Group IIIB element includes Ce; and the Group VIIB element includes Mn.

[0009] Optionally, the additive component further includes an oxide containing a third metal element, wherein the third metal element includes K and / or Mg; The molar ratio of chromium to any third metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2).

[0010] Optionally, in the XPS spectrum of the catalyst, Cr 3+ With Cr 6+ The peak area ratio is 0.6 to 9, preferably 1 to 6.

[0011] A second aspect of this disclosure provides a method for preparing the catalyst described in the first aspect of this disclosure, the method comprising: (1) A first mixture is obtained by mixing a chromium source, a first metal element source, a second metal element source, and water; the first mixture is then mixed with an alumina carrier and impregnated to obtain a second mixture. (2) The second mixture is dried and calcined; The chromium source includes a soluble salt of chromium; the first metal element source includes a soluble salt of a first metal element; and the second metal element source includes a soluble salt of a second metal element.

[0012] Optionally, in step (1), the specific surface area of ​​the alumina support is 50~550 m². 2 / g, pore size 3~50 nm, pore volume 0.2~1.2 cm³ 3 / g, saturated water absorption capacity is 55~95%; In the first mixture, the mass of water is 0.5 to 10 times the saturated water absorption capacity of the alumina carrier, preferably 0.9 to 2 times.

[0013] Optionally, in step (1), the molar ratio of chromium in the chromium source to any one of the first metal elements in the first metal element source is 1:(0.05~2), preferably 1:(0.2~1.2); the molar ratio of chromium in the chromium source to any one of the second metal elements in the second metal element source is 1:(0.05~2), preferably 1:(0.2~1.2).

[0014] Optionally, in step (1), the first mixture further includes a third metal source, the third metal source including a soluble salt of a third metal element, the third metal element including K and / or Mg; The molar ratio of chromium to any one of the third metal elements in the chromium source is 1:(0.05~2), preferably 1:(0.2~1.2).

[0015] Optionally, the conditions for the impregnation treatment include: rotating the first mixture and the alumina carrier at a pressure of -0.04 to -0.5 MPa, preferably -0.05 to -0.1 MPa, at a rotation speed of 200 to 500 rpm, for a time of 1 to 3 hours.

[0016] Optionally, the calcination conditions include: being carried out in an air atmosphere, at a temperature of 600~1200℃, preferably 780~1000℃; and for a time of 0.5~24h, preferably 6~12h. The drying temperature is 90~200℃. o C, preferably 100~140 o C, the drying time is 6~48h, preferably 12~24h.

[0017] This disclosure provides a third aspect regarding the application of the catalyst described in the first aspect of this disclosure in the dehydrogenation reaction of low-carbon alkanes.

[0018] Optionally, the reactants include C3-C4 alkanes, the reaction pressure is 0-1 MPa, the reaction temperature is 500-650 °C, and the mass hourly space velocity is 0.1-10 h⁻¹. -1 .

[0019] Through the above technical solution, the promoter component in the catalyst of this disclosure contains a variety of specific metal elements, wherein the first metal element includes one or more elements from Group IIIA and / or Group IVB; the second metal element includes any two or more elements from Group VIII, Group IB, Group IIB, Group IIIB, and Group VIIB. This disclosure, by adding specific metal elements, controls the Cr content of metallic chromium in the chromium oxide of the catalyst. 3+ -O sites further enhance catalyst activity and improve the yield of dehydrogenation of low-carbon alkanes to olefins.

[0020] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0021] Figure 1 This is the XPS spectrum of Cr element in the catalyst of Example 1 of this disclosure.

[0022] Figure 2 This is the XPS spectrum of Cr element in the catalyst of Example 2 of this disclosure.

[0023] Figure 3 This is the XPS spectrum of Cr element in the catalyst of Example 3 of this disclosure. Detailed Implementation

[0024] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0025] The first aspect of this disclosure provides a low-carbon alkane catalyst, the catalyst comprising an alumina support and an active component and an auxiliary component supported on the alumina support, the active component comprising a chromium oxide, and the auxiliary component comprising an oxide containing a first metal element and an oxide containing a second metal element, the first metal element comprising one or more elements from Group IIIA and / or Group IVB; the second metal element comprising any two or more elements from Group VIII, Group IB, Group IIB, Group IIIB, and Group VIIB.

[0026] The catalyst of this disclosure contains a variety of specific metal elements, wherein the first metal element includes one or more elements from Group IIIA and / or Group IVB; and the second metal element includes any two or more elements from Group VIII, Group IB, Group IIB, Group IIIB, and Group VIIB. This disclosure regulates the Cr content of metallic chromium in the chromium oxide of the catalyst by adding specific metal elements. 3+ -O sites further enhance catalyst activity and improve the yield of dehydrogenation of low-carbon alkanes to olefins.

[0027] According to one embodiment of this disclosure, based on the weight of the catalyst, the content of the alumina support is 58-99.4% by weight, preferably 55-90% by weight; the content of the active component, calculated as chromium oxide (Cr2O3), is 0.5-20% by weight, preferably 4-15% by weight; and the total content of the auxiliary agent, calculated as the oxide form of the auxiliary element, is 0.1-30% by weight, preferably 6-30% by weight. This embodiment is beneficial for improving the activity of the catalyst and increasing the yield of dehydrogenation of low-carbon alkanes to olefins. For example, based on the weight of the catalyst, the content of the alumina support can be any value within the range of 58% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, 95% by weight, 99.4% by weight, or any combination thereof.

[0028] According to one embodiment of this disclosure, the molar ratio of chromium to any first metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2); the molar ratio of chromium to any second metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2). The above embodiments are beneficial for improving the activity of the catalyst and increasing the yield of dehydrogenation of low-carbon alkanes to olefins.

[0029] According to one embodiment of this disclosure, the Group IIIA elements include Ga; the Group IVB elements include Ti; the Group VIII elements include Co and / or Ni; the Group IB elements include Cu; the Group IIB elements include Zn; the Group IIIB elements include Ce; and the Group VIIB elements include Mn. This embodiment is beneficial for improving the activity of the catalyst and increasing the yield of dehydrogenation of low-carbon alkanes to olefins.

[0030] According to one embodiment of this disclosure, the auxiliary component further includes an oxide containing a third metal element, wherein the third metal element includes K and / or Mg. The above embodiment is beneficial for improving the stability of the catalyst.

[0031] According to one embodiment of this disclosure, the molar ratio of chromium to any third metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2). This embodiment is beneficial for improving the activity of the catalyst and increasing the yield of olefins from the dehydrogenation of low-carbon alkanes.

[0032] According to one embodiment of this disclosure, the chromium oxide comprises Cr₂O₃ and CrO₃, and in the chromium XPS spectrum of the catalyst, Cr 3+ With Cr 6+ The peak area ratio is 0.6 to 9, preferably 1 to 6. The above embodiments are beneficial for improving the catalyst activity and increasing the yield of olefins from the dehydrogenation of low-carbon alkanes.

[0033] A second aspect of this disclosure provides a method for preparing the catalyst described in the first aspect of this disclosure, the method comprising: (1) A first mixture is obtained by mixing a chromium source, a first metal element source, a second metal element source, and water; the first mixture is then mixed with an alumina carrier and impregnated to obtain a second mixture. (2) The second mixture is dried and calcined; The chromium source includes a soluble salt of chromium; the first metal element source includes a soluble salt of the first metal element; and the second metal element source includes a soluble salt of the second metal element.

[0034] According to one embodiment of this disclosure, in step (1), the specific surface area of ​​the alumina carrier is 50~550 m². 2 / g, preferably 150~350 m 2 / g, pore size of 3~50nm, preferably 5~25nm, pore volume of 0.2~1.2 cm³ 3 / g, preferably 0.5~0.8 cm 3 / g, with a saturated water absorption capacity of 55-95%, preferably 70-80%; in the first mixture, the mass of water is 0.5-10 times the saturated water absorption capacity of the alumina support, preferably 0.9-2 times. The above embodiments are beneficial for improving the catalyst activity and increasing the yield of dehydrogenation of low-carbon alkanes to olefins.

[0035] According to one embodiment of this disclosure, in step (1), the molar ratio of chromium in the chromium source to any one of the first metal elements in the first metal element source is (0.05~2), preferably 1:(0.2~1.2); the Group IIIA element includes Ga, and the soluble salts including Group IIIA elements include, but are not limited to, one or more of chlorides, nitrates, sulfates, and oxalates; the Group IVB element includes Ti, and the soluble salts including Group IVB elements include, but are not limited to, one or more of chlorides, nitrates, sulfates, and oxalates. The above embodiment is beneficial for improving the activity of the catalyst and increasing the yield of dehydrogenation of low-carbon alkanes to olefins.

[0036] According to one embodiment of this disclosure, in step (1), the molar ratio of chromium in the chromium source to any one of the second metal elements in the second metal element source is (0.05~2), preferably 1:(0.2~1.2); the Group VIII element includes Co and / or Ni, and the soluble salts including the Group VIII element include, but are not limited to, one or more of chlorides, nitrates, sulfates, and oxalates; the Group IB element includes Cu, and the soluble salts including the Group IB element include, but are not limited to, one or more of chlorides, nitrates, sulfates, and oxalates; the Group IIB element includes Zn, the Group IIIB element includes Ce, and the soluble salts including the Group IIB element include, but are not limited to, one or more of chlorides, nitrates, sulfates, and oxalates; the Group VIIB element includes Mn, and the soluble salts including the Group VIIB element include, but are not limited to, one or more of chlorides, nitrates, sulfates, and oxalates. The above embodiments are beneficial for improving the activity of the catalyst and increasing the yield of dehydrogenation of low-carbon alkanes to olefins.

[0037] According to one embodiment of this disclosure, in step (1), the first mixture further includes a third metal element source, which includes a soluble salt of the third metal element; the third metal element includes K and / or Mg. The above embodiment is beneficial for improving the activity of the catalyst and increasing the yield of dehydrogenation of low-carbon alkanes to olefins.

[0038] According to one embodiment of this disclosure, the molar ratio of chromium in the chromium source to any one of the third metal elements in the third metal element source is 1:(0.05~2), preferably 1:(0.2~1.2). This embodiment is beneficial for improving the activity of the catalyst and increasing the yield of dehydrogenation of low-carbon alkanes to olefins.

[0039] According to one embodiment of this disclosure, the impregnation treatment conditions include: rotating the first mixture and the alumina support at a pressure of -0.04 to -0.5 MPa, preferably -0.05 to -0.1 MPa, at a rotation speed of 200 to 500 rpm, for a time of 1 to 3 hours. This embodiment is beneficial for improving the catalyst activity and increasing the yield of low-carbon alkane dehydrogenation to olefins.

[0040] According to one embodiment of this disclosure, the calcination conditions include: being carried out in an air atmosphere at a temperature of 600-1200°C, preferably 780-1000°C; and a time of 0.5-24 hours, preferably 6-12 hours. This embodiment is beneficial for improving the activity of the catalyst and increasing the yield of olefins from the dehydrogenation of low-carbon alkanes.

[0041] The method disclosed herein controls the ratio of chromium atoms to any first metal element and any second metal element in the catalyst to be 1:(0.05~2):(0.05~2), and the calcination temperature to be 600~1200℃. o C, which makes the chromium species in the chromium oxide in the catalyst... 3+ Cr 6+ The peak area ratio was 0.6-9, which improved the catalyst activity and the yield of dehydrogenation of low-carbon alkanes to olefins. In a further embodiment, the ratio of chromium atoms to the first metal element and the second metal atom in the catalyst was adjusted to 1:(0.2-1.2):(0.2-1.2), and the calcination temperature was set at 780-1000 °C. o C, which makes the chromium species in the chromium oxide in the catalyst... 3+ Cr 6+ The peak area ratio is 1~6, which further improves the catalyst activity and the yield of dehydrogenation of low-carbon alkanes to olefins.

[0042] According to one embodiment of this disclosure, the drying temperature is 90~200°C. o C, preferably 100~140 o C, the drying time is 6~48h, preferably 12~24h.

[0043] This disclosure provides a third aspect regarding the application of the catalyst described in the first aspect of this disclosure in the dehydrogenation reaction of low-carbon alkanes.

[0044] According to one embodiment of this disclosure, the reaction raw materials include C3-C4 alkanes, the reaction pressure is 0-1 MPa, the reaction temperature is 500-650°C, and the mass hourly space velocity is 0.1-10 h⁻¹. -1 .

[0045] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0046] All raw materials used in the examples were obtained commercially and, unless otherwise specified, were of analytical grade. The alumina support used in this disclosure was purchased from aladdin reagent, catalog number A396574, with a specific surface area of ​​220 m². 2 / g, pore size 15 nm, pore volume 0.64 cm³ 3 / g, with a saturated water absorption rate of 72%.

[0047] Example 1 8.43 g gallium chloride, 12.30 g cerium chloride, 4.50 g zinc chloride, 4.28 g cobalt chloride, 2.46 g potassium chloride, and 8.80 g chromium chloride were weighed and dissolved in 23.77 g deionized water. After thorough mixing, a first mixture was obtained, in which the mass of water was 1 times the saturated water absorption capacity of the alumina support. 31.68 g of the alumina support, dried at 120 °C for 4 h, was weighed and mixed with the first mixture. The mixture was then subjected to rotary adsorption at 250 rpm for 2 h under -0.08 MPa conditions. o The second mixture was obtained by drying at C for 12 h. The resulting second mixture was placed in air for 800 minutes. o The dehydrogenation catalyst was obtained by calcination at C for 8 h. The molar ratio of chromium to gallium in the chromium oxide was 1:1, the molar ratio of chromium to cerium was 1:1, the molar ratio of chromium to zinc was 1:1, the molar ratio of chromium to cobalt was 1:1, and the molar ratio of chromium to potassium was 1:1.

[0048] Example 2 8.43g gallium chloride, 12.30g cerium chloride, 4.50g zinc chloride, 4.28g cobalt chloride, and 8.80g chromium chloride were weighed and dissolved in 23.77g deionized water. After thorough mixing, a first mixture was obtained. In the first mixture, the mass of water was 1 times the saturated water absorption capacity of the alumina carrier. 31.68 g of the alumina support, dried at 120 °C for 4 h, was weighed and mixed with the first mixture mentioned above. The mixture was then subjected to rotary adsorption at 250 rpm for 2 h under -0.08 MPa conditions. Finally, the mixture was dried at 120 °C. o The second mixture was obtained by drying at C for 12 h. The resulting second mixture was placed in air for 800 minutes. oThe desired dehydrogenation catalyst was obtained by calcination at C for 8 h. The molar ratio of chromium to gallium in the chromium oxide was 1:1, the molar ratio of chromium to cerium in the chromium oxide was 1:1, the molar ratio of chromium to zinc in the chromium oxide was 1:1, and the molar ratio of chromium to cobalt in the chromium oxide was 1:1.

[0049] Example 3 1.52g of titanium chloride, 1.90g of nickel chloride, 2.98g of cerium chloride, 1.09g of zinc chloride, 0.60g of potassium chloride, and 4.26g of chromium chloride were weighed and dissolved in 33.48g of deionized water. After thorough mixing, a first mixture was obtained. In the first mixture, the mass of water was 0.9 times the saturated water absorption capacity of the alumina carrier. 44.64 g of alumina support dried at 140 °C for 4 h was weighed and mixed with the first mixture above. The mixture was then subjected to rotary adsorption at 300 rpm for 3 h under -0.06 MPa conditions to obtain the second mixture. The resulting second mixture was heated at 140°C. o After drying at C for 24 hours, it is then placed in air at 900°C. o The desired dehydrogenation catalyst was obtained by calcination at C for 10 h. The molar ratio of chromium to titanium in chromium oxide was 1:0.5, the molar ratio of chromium to cerium in chromium oxide was 1:0.5, the molar ratio of chromium to zinc in chromium oxide was 1:0.5, the molar ratio of chromium to nickel in chromium oxide was 1:0.5, and the molar ratio of chromium to potassium in chromium oxide was 1:0.5.

[0050] Example 4 2.11 g gallium chloride, 3.07 g cerium chloride, 1.12 g zinc chloride, 0.62 g potassium chloride and 8.79 g chromium chloride were weighed and dissolved in 31.48 g deionized water. After thorough mixing, a first mixture was obtained. In the first mixture, the mass of water was 1.2 times the saturated water absorption capacity of the alumina carrier. 41.96 g of alumina support dried at 125 °C for 5 h was weighed and subjected to rotary adsorption with the first mixture above at 350 rpm for 2.5 h under -0.07 MPa conditions to obtain the second mixture. The resulting second mixture was heated at 160°C. o After drying at C for 18 hours, it is then placed in air at 850°C. oThe desired dehydrogenation catalyst was obtained by calcination at C for 12 h. The molar ratio of chromium to gallium in the chromium oxide was 1:0.25, the molar ratio of chromium to cerium in the chromium oxide was 1:0.25, the molar ratio of chromium to zinc in the chromium oxide was 1:0.25, and the molar ratio of chromium to potassium in the chromium oxide was 1:0.25.

[0051] Example 5 1.46 g of nickel nitrate, 2.61 g of cerium nitrate, 1.52 g of titanium tetrachloride, 1.43 g of manganese nitrate, and 4.26 g of chromium chloride were weighed and dissolved in 20 g of deionized water. After thorough mixing, a first mixture was obtained. In the first mixture, the mass of water was 1.8 times the saturated water absorption capacity of the alumina carrier. 20g of alumina support dried at 110 °C for 2.5 h was weighed and mixed with the first mixture above. The mixture was then subjected to rotary adsorption at 200 rpm for 1.5 h under -0.065 MPa conditions to obtain the second mixture. The resulting second mixture was heated at 160°C. o After drying at C for 18 hours, it is then placed in air at 850°C. o The desired dehydrogenation catalyst was obtained by calcination at C for 12 h. The molar ratio of chromium to nickel in chromium oxide was 1:0.5, the molar ratio of chromium to cerium in chromium oxide was 1:0.5, the molar ratio of chromium to titanium in chromium oxide was 1:0.5, and the molar ratio of chromium to manganese in chromium oxide was 1:0.5.

[0052] Example 6 4.84 g of nickel oxalate, 4.84 g of cobalt oxalate, 6.26 g of titanium tetrachloride, 3.97 g of magnesium sulfate, and 8.79 g of chromium chloride were weighed and dissolved in 24.62 g of deionized water. After thorough mixing, a first mixture was obtained. In the first mixture, the mass of water was 1.3 times the saturated water absorption capacity of the alumina carrier. 32.82 g of alumina support dried at 110 °C for 2.5 h was weighed and mixed with the first mixture above. The mixture was then subjected to rotary adsorption at 280 rpm for 2 h under -0.08 MPa conditions to obtain the second mixture. The resulting second mixture was heated at 160°C. o After drying at C for 18 hours, it is then placed in air at 800°C. o The desired dehydrogenation catalyst was obtained by calcination at C for 11 h. The molar ratio of chromium to nickel in the chromium oxide was 1:1, the molar ratio of chromium to cobalt in the chromium oxide was 1:1, the molar ratio of chromium to titanium in the chromium oxide was 1:1, and the molar ratio of chromium to magnesium in the chromium oxide was 1:1.

[0053] Example 7 This embodiment uses the same method as Embodiment 1, the only difference being that the second mixture is in an air atmosphere at 600°C. o Calcined at C for 4 h, the remaining process was the same as in Example 1. Tests showed that the molar ratio of chromium to gallium in the chromium oxide was 1:1; the molar ratio of chromium to cerium in the chromium oxide was 1:1; the molar ratio of chromium to zinc in the chromium oxide was 1:1; the molar ratio of chromium to cobalt in the chromium oxide was 1:1; and the molar ratio of chromium to potassium in the chromium oxide was 1:1.

[0054] Example 8 This embodiment uses the same method as Embodiment 1, except that: 100g of deionized water is used to prepare the first mixture, and the mass of water in the first mixture is 0.5 times the saturated water absorption capacity of the alumina carrier. Tests showed that the molar ratio of chromium to gallium in the chromium oxide was 1:1; the molar ratio of chromium to cerium in the chromium oxide was 1:1; the molar ratio of chromium to zinc in the chromium oxide was 1:1; the molar ratio of chromium to cobalt in the chromium oxide was 1:1; and the molar ratio of chromium to potassium in the chromium oxide was 1:1.

[0055] Example 9 This embodiment uses the same method as Embodiment 3, except that the amount of titanium chloride used is 4.55g, nickel chloride 5.70g, cerium chloride 12.29g, zinc chloride 4.50g, and potassium chloride 2.46g. Tests showed that the molar ratio of chromium to titanium in the chromium oxide was 1:1.5, the molar ratio of chromium to nickel was 1:1.5, the molar ratio of chromium to cerium was 1:2, the molar ratio of chromium to zinc was 1:2, and the molar ratio of chromium to potassium was 1:2.

[0056] Comparative Example 1 The method of Comparative Example 1 is the same as that of Example 5, except that titanium tetrachloride is not added when preparing the catalyst in this comparative example.

[0057] Test Example 1 The component content of the catalyst was determined using a Thermo iCAP PRO ICP-OES inductively coupled plasma atomic emission spectrometer; the valence state of Cr in the catalyst was determined using a Thermo VG ESCALAB 250 spectrometer XPS instrument, and the Cr content was calculated. 3+ With Cr 6+ The peak area ratio was determined using Gaussian fitting, and the test results are shown in Table 1 and 2. Figures 1-3 As shown.

[0058] Table 1

[0059] Reaction Example The dehydrogenation catalysts obtained in Examples 1-9 and Comparative Example 1 were tested for propane dehydrogenation to olefins. The reaction methods are as follows: Propane gas is introduced into the reaction zone by adjusting the flow rate through a mass flow meter. Both the heating section and the reaction section of the reactor are heated by electric heating wires to reach the predetermined temperature. After the reaction, the gas passes through a condenser and then enters a gas chromatograph to analyze its composition. The catalyst evaluation conditions in the isothermal fixed-bed reactor are as follows: approximately 1.5 grams of catalyst are placed in the isothermal reactor, the reaction pressure is 0.03 MPa, and the gas hourly space velocity (GHSV) is 3.5 h⁻¹. -1 The reaction temperature was 600℃; the reaction results are shown in Table 2.

[0060] Table 2

[0061] In Table 2, stability is expressed as the inactivation rate, which represents the degree to which the activity decreases per unit time.

[0062] According to the data in Table 2, the catalyst of this disclosure exhibits higher activity and a higher olefin yield in propane-to-olefin production. Comparing Example 7 with Example 1 shows that within the preferred calcination conditions of this disclosure, the catalyst exhibits higher activity and a higher yield of olefins from low-carbon alkanes. Comparing Example 8 with Example 1 shows that within the preferred mass range of water in the first mixture of this disclosure, the catalyst exhibits higher activity and a higher yield of olefins from low-carbon alkanes. Comparing Example 9 with Example 3 shows that within the preferred molar ratio range of chromium to the first and second metal elements of this disclosure, the catalyst exhibits higher activity and a higher yield of olefins from low-carbon alkanes.

[0063] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0064] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0065] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A low-carbon alkane catalyst, characterized in that, The catalyst comprises an alumina support and an active component and an auxiliary component supported on the alumina support. The active component comprises chromium oxide, and the auxiliary component comprises an oxide containing a first metal element and an oxide containing a second metal element. The first metal element comprises one or more elements from Group IIIA and / or Group IVB. The second metal element comprises any two or more elements from Group VIII, Group IB, Group IIB, Group IIIB, and Group VIIB.

2. The catalyst according to claim 1, wherein, Based on the weight of the catalyst, the content of the alumina support is 50-99.4% by weight, preferably 55-90% by weight, the content of the active component is 0.5-20% by weight, preferably 4-15% by weight, and the total content of the auxiliary components is 0.1-30% by weight, preferably 6-30% by weight.

3. The catalyst according to claim 1, wherein, The molar ratio of chromium to any first metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2); the molar ratio of chromium to any second metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2). Preferably, the Group IIIA element includes Ga; the Group IVB element includes Ti; the Group VIII element includes Co and / or Ni; the Group IB element includes Cu; the Group IIB element includes Zn; the Group IIIB element includes Ce; and the Group VIIB element includes Mn.

4. The catalyst according to claim 1, wherein, The additive component also includes an oxide containing a third metal element, wherein the third metal element includes K and / or Mg; The molar ratio of chromium to any third metal element in the chromium oxide is 1:(0.05~2), preferably 1:(0.2~1.2).

5. The catalyst according to claim 1, wherein, In the XPS spectrum of the catalyst, Cr 3+ With Cr 6+ The peak area ratio is 0.6 to 9, preferably 1 to 6.

6. A method for preparing the catalyst according to any one of claims 1 to 5, characterized in that, The method includes: (1) A first mixture is obtained by mixing a chromium source, a first metal element source, a second metal element source, and water; the first mixture is then mixed with an alumina carrier and impregnated to obtain a second mixture. (2) The second mixture is dried and calcined; The chromium source includes a soluble salt of chromium; the first metal element source includes a soluble salt of the first metal element; and the second metal element source includes a soluble salt of the second metal element.

7. The method according to claim 6, wherein, In step (1), the specific surface area of ​​the alumina carrier is 50~550 m². 2 / g, pore size 3~50 nm, pore volume 0.2~1.2 cm³ 3 / g, saturated water absorption capacity is 55~95%; In the first mixture, the mass of water is 0.5 to 10 times the saturated water absorption capacity of the alumina carrier, preferably 0.9 to 2 times.

8. The method according to claim 6, wherein, In step (1), the molar ratio of chromium in the chromium source to any one of the first metal elements in the first metal element source is 1:(0.05~2), preferably 1:(0.2~1.2); the molar ratio of chromium in the chromium source to any one of the second metal elements in the second metal element source is 1:(0.05~2), preferably 1:(0.2~1.2).

9. The method according to claim 6, wherein, In step (1), the first mixture further includes a third metal element source, which includes a soluble salt of the third metal element, and the third metal element includes K and / or Mg; The molar ratio of chromium to any one of the third metal elements in the chromium source is 1:(0.05~2), preferably 1:(0.2~1.2).

10. The method according to claim 6, wherein, The conditions for the impregnation treatment include: rotating the first mixture and the alumina carrier at a pressure of -0.04 to -0.5 MPa, preferably -0.05 to -0.1 MPa, at a rotation speed of 200 to 500 rpm, for a time of 1 to 3 hours.

11. The method according to claim 6, wherein, The calcination conditions include: being carried out in an air atmosphere, at a temperature of 600~1200℃, preferably 780~1000℃; and for a time of 0.5~24h, preferably 6~12h. The drying temperature is 90~200℃. o C, preferably 100~140 o C, the drying time is 6~48h, preferably 12~24h.

12. The use of the catalyst according to any one of claims 1 to 5 in the dehydrogenation reaction of low-carbon alkanes.

13. The application according to claim 12, wherein, The reactants consist of C3-C4 alkanes, the reaction pressure is 0-1 MPa, the reaction temperature is 500-650℃, and the mass hourly space velocity (HHSV) is 0.1-10 h⁻¹. -1 .

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