CN114588899A - Catalyst and preparation and application thereof - Google Patents

Abstract

The present invention relates to a catalyst and its preparation and application. The bimetal compounded by Group IV element metal and Group II element metal is used as auxiliary agent, platinum group element metal is used as active component of catalyst, and magnesium aluminum spinel is used as catalyst. for the carrier. The preparation process of the catalyst includes the following steps: introducing the metal auxiliaries of the Group IV elements and the metal additives of the Group II elements into the magnesium aluminum spinel carrier by a co-impregnation method, so that the metal atoms of the Group IV elements are more uniformly dispersed in the carrier at the atomic level, At the same time, the number of basic sites on the surface of the magnesium-aluminum spinel support is regulated by the oxides of group II element metals to increase its force; The dehydrogenation active component is impregnated on the spar carrier to improve the interaction force between the metal-auxiliary-carrier; finally, the catalyst is obtained by drying and roasting. The catalyst of the invention can be used in the dehydrogenation reaction of light alkane, and has the advantages of high conversion rate, high olefin yield, good catalyst stability and the like.

Description

A catalyst and its preparation and application

technical field

The invention relates to a catalyst for dehydrogenation of low-carbon alkanes to olefins and a preparation method thereof, and a catalyst for producing olefins by dehydrogenation of low-carbon alkanes containing bimetallic additives of Group IV element metals and Group II element metals, and magnesium-aluminum spinel as a carrier. The invention discloses a catalyst preparation method for the reaction activity and stability of low-carbon alkane dehydrogenation to olefin, belonging to the catalyst preparation technology in the technical field of industrial catalysis.

Background technique

Low-carbon olefins are important petrochemical raw materials, mainly from the cracking of naphtha to produce ethylene, and C3-C4 olefins are its by-products. In recent years, the demand for light olefins has been increasing. As the price of naphtha has risen, people have begun to seek cheaper feedstocks to produce light olefins. At present, most of the low-carbon and low-carbon alkanes in natural gas, oilfield gas and refinery gas in my country are used as fuels, and they have not been fully utilized, and the domestic low-carbon olefins, especially propylene raw materials, are seriously insufficient. If the low-carbon low-carbon alkanes can be directly converted into low-carbon olefins, it will not only solve the problem of insufficient sources of low-carbon olefin raw materials, but also improve the utilization value of the low-carbon low-carbon alkanes. Therefore, the development of the process of preparing low-carbon olefins from low-carbon low-carbon alkanes is of great significance for the rational utilization of C3-C4 low-carbon alkanes and the development of new sources of low-carbon olefins.

The catalytic dehydrogenation reaction of low-carbon alkanes is limited by thermodynamic equilibrium, and it is prone to cracking and deep dehydrogenation of low-carbon alkanes, and the selectivity decreases; meanwhile, the carbon on the catalyst surface is accelerated and deactivated rapidly. The industrial application of this method is limited due to the low conversion of light alkanes and short catalyst life. Therefore, the development of catalysts for dehydrogenation of light alkanes to olefins with high activity, selectivity and high stability has become the key to this technology. Chinese patent CN200710025372.X discloses a preparation method of a medium-porous molecular sieve modified by alumina as a carrier impregnated with platinum-tin component catalyst, the propane conversion rate is only 17%, and the propane selectivity is 93%. Chinese patent CN200910011770.5 discloses a propane dehydrogenation catalyst in which Sn is introduced into an alumina carrier step by step and a platinum group catalyst is used as an active component. The catalyst has high selectivity and stability. Chinese Patent No. 200910011772.4 discloses a propane dehydrogenation catalyst containing Sn on alumina carrier. In this invention, Sn is introduced into the carrier when alumina is gelled, and carbon nanofibers are supported on the carrier in situ by ethylene cracking. The catalyst is used for propane The activity, selectivity and stability of the dehydrogenation catalyst are greatly improved. Chinese patent 200910057235.3 adopts the sol-gel method to introduce the tin component into the aluminum sol, and load the platinum component and other metal additives after drying and molding. This process solves the problem that the Sn component is easily reduced and precipitated during the high temperature process, thereby affecting the performance of the catalyst. . Chinese patent 201010510192.2 provides a catalyst for dehydrogenation of propane to propylene with SBA-15 molecular sieve containing SnAl bimetal as a carrier, and an inorganic oxide as a binder for molding. The catalyst has excellent carbon deposition resistance, high propane dehydrogenation conversion, selectivity and reaction stability.

The mass ratios of Sn/Pt in the above catalysts are all high (2-25), and Sn is prone to be reduced and precipitated during the high temperature reaction, which affects the activity and selectivity of the catalyst, resulting in irreversible deactivation. The Sn co-agent is impregnated on the surface of the support by conventional methods, and its direct interaction with the support is weak, and it is easily reduced to cause catalyst deactivation. Although the dehydrogenation conversion rate and olefin selectivity of low-carbon alkanes are high under certain conditions, the catalyst is prone to carbon deposition and deactivation under high temperature conditions, resulting in poor reaction stability and short service life of the catalyst.

At present, most of the low-carbon alkane dehydrogenation catalyst supports are alumina. However, there are a small amount of moderately strong acid sites on the surface of alumina, so the dehydrogenation process is often accompanied by side reactions, resulting in surface carbon and serious catalyst deactivation. Considering the stability of the catalyst, the dehydrogenation performance of the existing alumina supports is still unsatisfactory. The existing research is mainly to improve the catalytic reaction stability of the catalyst by adding various promoters and changing the types of supports. Magnesium aluminum spinel (MgAl ₂ O ₄ ) has high thermal stability, high mechanical strength and hardness, and has the advantages of good corrosion resistance and low thermal expansion coefficient. The unique surface properties of these active centers make them widely used as catalysts and catalyst supports in chemical reactions.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the purpose of the present invention is to provide a catalyst for dehydrogenation of light alkanes to olefins and a preparation method thereof. The present invention can obtain a kind of supported Group IV element metal and transition metal bimetallic A catalyst with high activity and high reaction stability supported by additives, low Sn/Pt ratio and transition metal spinel has obvious social and economic benefits.

In the catalyst prepared by the invention for dehydrogenation of low-carbon alkanes to olefins, magnesium aluminum spinel is used as a carrier, group IV element metals and group II element metals are used as bimetallic auxiliary agents, and platinum group element metals are used as bimetallic additives. Dehydrogenation active components.

The preparation method of the catalyst provided by the invention for the dehydrogenation of light alkanes to olefins, the process is:

(1) The magnesia-aluminum spinel carrier is put into the solution containing the metal salt of the auxiliary group II element and the metal salt of the group IV element by the co-impregnation method, and is impregnated for 2-24 hours. The catalyst carrier is obtained after drying at 60-120°C for 2-24h, and calcining at 350-800°C for 5-30h.

(2) Using a vacuum impregnation method, the active components of the catalyst are supported on the catalyst carrier obtained in the step (1). The sample was dried at 60-120°C for 2-24h, and calcined at 350-800°C for 2-12h to obtain a dehydrogenation catalyst.

The metal salt of the Group IV element described in the step (1) is one or more of the nitrates or chlorides of germanium or tin, and the metal salt of the Group II element is the nitrate of the Group II element metal or One or more of chlorides or organic acid salts.

The active component of the catalyst described in the step (2) is a combination of one or more of the platinum group element metals platinum, palladium, iridium, rhomb or osmium; when the above-mentioned active component is platinum, the used platinum source It is one or more of chloroplatinic acid, platinum ammonia or oxyplatinum acetylacetonate, and other active components also use corresponding metal chlorides or organic complexes.

Calculated based on the mass of the magnesia-aluminum spinel carrier, the mass percentage of Group IV element metals in the additive is 0.005 to 3.0 wt.%, and the mass percentage of Group II element metals is 0.005 to 6.0 wt.%. The active component of the catalyst is metal Pt with a mass percentage content of 0.005-1.0 wt.%.

The mass ratio of the auxiliary group II element metal to the group IV element metal in the step (1) is 0.0005-15.0.

The magnesia-aluminum spinel carrier described in step (1) is formed magnesia-aluminum spinel or powdered magnesia-aluminum spinel.

The mass ratio of the metal auxiliary agent of the group IV element and the metal of the active component platinum group element is 0.0005-2.0.

Group IV element metal and group II element metal auxiliary are introduced into the magnesium aluminum spinel carrier by co-impregnation, and the dehydrogenation active component Pt group metal element is introduced into the carrier by vacuum impregnation.

The auxiliary agent described in step 1 is that the group IV element metal is selected from one or more combinations of germanium and tin, and the group II element metal is selected from one or more of Mg, Ca, Sr, and Ba. Metal combination. The salt solutions used may be nitrates, chlorides and organic acid salts such as _SnCl4 , SnCl2, Mg( _NO3 ) ₃ , Mg( _{CH3COO )2 and} the like.

The magnesia-aluminum spinel carrier described in step 1 includes self-made spherical, strip and granular magnesia-aluminum spinel and self-made powdery magnesia-aluminum spinel carrier.

In the above technical solution, the drying temperature in steps (1) and (2) is preferably 100-120°C, the drying time is preferably 4-6h, the roasting temperature is preferably 450-550°C, and the roasting time is preferably 10-12h.

The catalyst for producing olefins by dehydrogenation of light alkanes in the present invention adopts a fluidized bed, moving bed or fixed bed reactor, preferably a fixed bed reactor. Reaction conditions: normal pressure; the reaction temperature is 590 ℃; the mass space velocity of the low-carbon alkane is 6.0h ^-1 ; the hydrogen-hydrocarbon ratio is 1.0; Conversion, olefin selectivity, and yield.

The characteristics of the present invention are:

(1) The introduction of Group IV element metals such as Sn and Group II element metals such as Mg in the form of composite double additives on the magnesium aluminum spinel support by co-impregnation method can make Sn more uniform in the support at the atomic level Dispersion, by regulating the number of basic sites on the surface of the carrier, to improve the full effect of the S assistant and the carrier. The Mg and Sn additives introduced by co-impregnation form fresh MgO islands after roasting, which can provide abundant basic sites and act as bridges to greatly increase the force between the additives Sn atoms and the magnesia-aluminum spinel carrier, which is beneficial to The reduction of Sn ⁴⁺ to zero-valent Sn ⁰ is inhibited, thereby improving the dehydrogenation activity and stability of the catalyst.

As shown in Figure 1, it can be found that using different magnesia-aluminum spinels as carriers, co-impregnating Group IV element metals such as Sn and Group II element metals such as Mg as auxiliary agents, and supporting Pt as the active component of the catalyst. The conversion, olefin yield and stability of the isobutane dehydrogenation catalyst were significantly improved. As shown in Figure 2, it can be found that magnesium aluminum spinel is used as the carrier, co-impregnated with Group IV element metals such as Sn and different Group II element metals as auxiliary agents, and supported Pt as the active component of the catalyst. The conversion rate, olefin yield and stability of the butane dehydrogenation catalyst were significantly improved.

(2) A catalyst for dehydrogenation of low-carbon alkanes to olefins is prepared by using magnesium-aluminum spinel with Sn and Mg as bimetallic additives as a carrier, and supporting platinum group metal, II and IV elements by impregnation method. In the catalyst prepared by this method, the Mg and Sn bimetallic auxiliary islands are beneficial to improve the interaction between the active components of platinum group elements and the basic magnesium oxide on the surface, thereby improving the interaction force with the support and its dispersion and stability on the surface of the support. properties, thereby preventing the agglomeration of dehydrogenation-active metals during the reaction. The post-impregnated Mg promoter on the magnesia-alumina spinel support can form fresh magnesium oxide islands and improve the direct metal-coagent-support interaction, thereby improving the dehydrogenation activity, olefin selectivity and catalyst stability of the catalyst sex.

(3) The ultra-low Sn/Pt ratio in the present invention and the ultra-strong interaction between the two effectively reduce the reduction of Sn ⁴⁺ to metal Sn during the reaction process, thereby contributing to the improvement of catalyst activity, stability and olefin yield .

Description of drawings

Figure 1. Isobutene conversion, isobutene selectivity, and isobutene yield for isobutane dehydrogenation over Pt-Sn-Mg/magnesium-aluminum spinel catalysts. Evaluation conditions: catalyst mass 1.9 g, isobutene mass space velocity 6 h ^-1 , normal pressure, reaction temperature 590°C, and hydrogen/isobutene volume ratio of 1:1.

Fig. 2 Isobutene conversion, isobutene selectivity and isobutene yield for isobutane dehydrogenation over Pt-Sn-M/magnesium aluminum spinel (M=Ca, Sr and Ba) catalysts. Evaluation conditions: catalyst mass 1.9 g, isobutene mass space velocity 6 h ^-1 , normal pressure, reaction temperature 590°C, and hydrogen/isobutene volume ratio of 1:1.

Detailed ways

Example 1

The Sn-Mg/MgAl ₂ O ₄ carrier was prepared by impregnation method. Take 2ml Mg(NO ₃ ) ₂ (0.05g Mg/ml) solution and 2.44ml (0.025gSn/ml) SnCl ₄ with a mass concentration of 10% dilute hydrochloric acid solution into a 200ml beaker, add 4ml deionized water, and mix well. 10 g of magnesium-aluminum spinel pellets were weighed and added to the above solution, and placed for adsorption for 4 h. Drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 12h to obtain a catalyst carrier with dual promoters.

Take 10g of the above carrier and put it into a 250ml suction filter bottle and vacuumize for 0.5h. 1.35ml (0.037gPt/ml) of chloroplatinic acid solution and 2.4ml of 10% mass concentration of dilute hydrochloric acid were added. The catalyst was obtained by drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 4h.

Evaluation conditions: The catalyst was reduced with hydrogen at 480 °C for 2 h before the isobutane dehydrogenation reaction, and used for the isobutane dehydrogenation reaction. The mass of the catalyst was 1.9 g, the mass space velocity of isobutane was 6 h ^-1 , the pressure was normal, the reaction temperature was 590° C., and the volume ratio of hydrogen/propane was 1:1.

The reaction results are as follows: after 10h of reaction, the isobutane conversion rate of isobutane dehydrogenation to isobutene catalyst supported by Sn-Mg bimetallic auxiliaries magnesium aluminum spinel is 49.7%, isobutene selectivity is 89.1%, isobutene The yield was 44.3% (Table 1).

Example 2

The Sn-Mg/MgAl ₂ O ₄ carrier was prepared by impregnation method. Take 4.5ml MgCl ₂ (0.05g Mg/ml) solution and 2.44ml (0.025gSn/ml) SnCl ₄ dilute hydrochloric acid solution into a 200ml beaker, add 2ml deionized water, and mix well. 10 g of magnesium-aluminum spinel pellets were weighed and added to the above solution, and placed for adsorption for 4 h. Drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 12h to obtain a catalyst carrier with dual promoters.

Take 10g of the above carrier and put it into a 250ml suction filter bottle and vacuumize for 0.5h. 1.35 ml (0.037 gPt/ml) of chloroplatinic acid solution and 2.4 ml of 10% dilute hydrochloric acid were added. The catalyst was obtained by drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 4h.

Evaluation conditions: The catalyst was reduced with hydrogen at 480 °C for 2 h before the isobutane dehydrogenation reaction, and used for the isobutane dehydrogenation reaction. The mass of the catalyst was 1.9 g, the mass space velocity of isobutane was 6 h ^-1 , the pressure was normal, the reaction temperature was 590° C., and the volume ratio of hydrogen/propane was 1:1.

The reaction results are as follows: after 10h of reaction, the isobutane conversion rate of isobutane dehydrogenation to isobutene catalyst supported by Sn-Mg bimetallic auxiliaries magnesium aluminum spinel is 48.9%, isobutene selectivity is 90.8%, isobutene The yield was 44.3% (Table 1).

Example 3

The Sn-Mg/MgAl ₂ O ₄ carrier was prepared by impregnation method. Take 9ml Mg(CH ₃ COO) ₂ (0.05gMg/ml) solution and 2.44ml (0.025gSn/ml) SnCl ₄ dilute hydrochloric acid solution into a 200ml beaker and mix well. 10 g of magnesium-aluminum spinel pellets were weighed and added to the above solution, and placed for adsorption for 4 h. Drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 12h to obtain a catalyst carrier with dual promoters.

Take 10g of the above carrier and put it into a 250ml suction filter bottle and vacuumize for 0.5h. 1.35 ml (0.037 gPt/ml) of chloroplatinic acid solution and 2.4 ml of 10% dilute hydrochloric acid were added. The catalyst was obtained by drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 4h.

Evaluation conditions: The catalyst was reduced with hydrogen at 480 °C for 2 h before the isobutane dehydrogenation reaction, and used for the isobutane dehydrogenation reaction. The mass of the catalyst was 1.9 g, the mass space velocity of isobutane was 6 h ^-1 , the pressure was normal, the reaction temperature was 590° C., and the volume ratio of hydrogen/propane was 1:1.

The reaction results are as follows: after 10h of reaction, the isobutane conversion rate of isobutane dehydrogenation to isobutene catalyst supported by Sn-Mg bimetallic auxiliaries magnesium aluminum spinel is 47.8%, isobutene selectivity is 90.1%, isobutene The yield was 43.0% (Table 1).

Table 1 Isobutane conversion, isobutene selectivity and isobutene yield of Pt-Sn-Mg/magnesium aluminum spinel catalyst for isobutane dehydrogenation for 10 h. Evaluation conditions: catalyst mass 1.9 g, isobutane mass space velocity 6 h ^-1 , normal pressure, reaction temperature 590°C, and hydrogen/propane volume ratio of 1:1.

Example 4

The Sn-Ca/MgAl ₂ O ₄ carrier was prepared by impregnation method. Take 2ml Ca(CH ₃ COO) ₂ (0.05gCa/ml) solution and 2.44ml (0.025gSn/ml) SnCl ₄ dilute hydrochloric acid solution into a 200ml beaker, add 4ml deionized water, and mix well. 10 g of magnesium-aluminum spinel strips were weighed and added to the above solution, and placed for adsorption for 4 h. Drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 12h to obtain a catalyst carrier with dual promoters.

Take 10g of the above carrier and put it into a 250ml suction filter bottle and vacuumize for 0.5h. 1.35 ml (0.037 gPt/ml) of chloroplatinic acid solution and 2.4 ml of 10% dilute hydrochloric acid were added. The catalyst was obtained by drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 4h.

Evaluation conditions: The catalyst was reduced with hydrogen at 480 °C for 2 h before the isobutane dehydrogenation reaction, and used for the isobutane dehydrogenation reaction. The mass of the catalyst was 1.9 g, the mass space velocity of isobutane was 6 h ^-1 , the pressure was normal, the reaction temperature was 590° C., and the volume ratio of hydrogen/propane was 1:1.

The reaction results are as follows: after 10 hours of reaction, the isobutane conversion rate of isobutane dehydrogenation to isobutene catalyst supported by Sn-Ca bimetallic auxiliaries magnesium aluminum spinel is 53.2%, isobutene selectivity is 85.4%, isobutene The yield was 45.4% (Table 2).

Example 5

The Sn-Sr/MgAl ₂ O ₄ carrier was prepared by impregnation method. Take 4.5ml Sr(NO ₃ ) ₂ (0.05gSr/ml) solution and 2.44ml (0.025gSn/ml) SnCl ₄ dilute hydrochloric acid solution into a 200ml beaker, add 2ml deionized water, and mix well. Weigh 10 g of magnesium-aluminum spinel powder into the above solution, and place it for adsorption for 4 h. Drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 12h to obtain a catalyst carrier with dual promoters.

Take 10g of the above carrier and put it into a 250ml suction filter bottle and vacuumize for 0.5h. 1.35 ml (0.037 gPt/ml) of chloroplatinic acid solution and 2.4 ml of 10% dilute hydrochloric acid were added. The catalyst was obtained by drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 4h.

Evaluation conditions: The catalyst was reduced with hydrogen at 480 °C for 2 h before the isobutane dehydrogenation reaction, and used for the isobutane dehydrogenation reaction. The mass of the catalyst was 1.9 g, the mass space velocity of isobutane was 6 h ^-1 , the pressure was normal, the reaction temperature was 590° C., and the volume ratio of hydrogen/propane was 1:1.

The reaction results are as follows: after 10h of reaction, the isobutane conversion rate of the isobutane dehydrogenation to isobutene catalyst supported by the Sn-Sr bimetallic auxiliaries magnesium aluminum spinel is 47.6%, the isobutene selectivity is 91.7%, the isobutene The yield was 43.7% (Table 2).

Example 6

The Sn-Ba/MgAl ₂ O ₄ carrier was prepared by impregnation method. Put 9ml of Ba(NO ₃ ) ₂ (0.05gBa/ml) solution and 2.44ml (0.025gSn/ml) of SnCl ₄ in dilute hydrochloric acid solution into a 200ml beaker and mix well. 10 g of magnesium-aluminum spinel was weighed and added to the above solution, and placed for adsorption for 4 h. Drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 12h to obtain a catalyst carrier with dual promoters.

Take 10g of the above carrier and put it into a 250ml suction filter bottle and vacuumize for 0.5h. 1.35 ml (0.037 gPt/ml) of chloroplatinic acid solution and 2.4 ml of 10% dilute hydrochloric acid were added. The catalyst was obtained by drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 4h.

Evaluation conditions: The catalyst was reduced with hydrogen at 480 °C for 2 h before the isobutane dehydrogenation reaction, and used for the isobutane dehydrogenation reaction. The mass of the catalyst was 1.9 g, the mass space velocity of isobutane was 6 h ^-1 , the pressure was normal, the reaction temperature was 590° C., and the volume ratio of hydrogen/propane was 1:1.

The reaction results are as follows: after 10h of reaction, the isobutane conversion rate of isobutane dehydrogenation to isobutene catalyst supported by Sn-Ba bimetallic auxiliaries magnesium aluminum spinel is 50.3%, isobutene selectivity is 86.8%, isobutene The yield was 43.6% (Table 2).

Comparative example

Pt-Sn/MgAl ₂ O ₄ supports were prepared by impregnation method in order to compare the performance of the catalysts with Mg-Sn bimetallic auxiliaries supported by magnesium-aluminum spinel pellets. Take 2.44ml (0.025gSn/ml) of the diluted hydrochloric acid solution of _SnCl4 into a 200ml beaker, add 20ml of deionized water, and mix well. 10 g of magnesium-aluminum spinel pellets were weighed and added to the above solution, and placed for adsorption for 4 h. Drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 12h to obtain a catalyst carrier with dual promoters.

Take 10g of the above carrier and put it into a 250ml suction filter bottle and vacuumize for 0.5h. 1.35 ml (0.037 gPt/ml) of chloroplatinic acid solution and 2.4 ml of 10% dilute hydrochloric acid were added. The catalyst was obtained by drying at 60°C for 4h, drying at 120°C for 4h, and calcining at 550°C for 4h.

Evaluation conditions: The catalyst was reduced with hydrogen at 480 °C for 2 h before the isobutane dehydrogenation reaction, and used for the isobutane dehydrogenation reaction. The mass of the catalyst was 1.9 g, the mass space velocity of isobutane was 6 h ^-1 , the pressure was normal, the reaction temperature was 590° C., and the volume ratio of hydrogen/propane was 1:1.

The reaction results are as follows: after the reaction for 10 hours, the isobutane conversion rate of the isobutane dehydrogenation to isobutene catalyst supported by the magnesium aluminum spinel as a Sn assistant is 40.5%, the isobutene selectivity is 92.7%, and the isobutene yield is 37.5%. %(Table 1).

Table 2 Isobutane conversion, isobutene selectivity and isobutene yield of Pt-Sn-M/magnesium aluminum spinel catalyst (M=Ca, Sr and Ba) isobutane dehydrogenation reaction for 10h. Evaluation conditions: catalyst mass 1.9 g, isobutane mass space velocity 6 h ^-1 , normal pressure, reaction temperature 590°C, and hydrogen/propane volume ratio of 1:1.

Claims (9)

1. a preparation method of catalyzer is characterized in that: preparation process is: (1) The magnesia-aluminum spinel carrier is put into the solution containing the metal salt of the group II element and the metal salt of the group IV element by the co-impregnation method, immersed for 2-24 hours; dried at 60-120 ° C for 2-24 hours, The catalyst carrier is obtained after roasting at 350-800℃ for 5-30h; (2) Using the vacuum impregnation method, the active components of the catalyst are supported on the catalyst carrier obtained in step (1); after loading, the sample is dried at 60-120°C for 2-24h, and calcined at 350-800°C for 2-24h to obtain dehydrogenation catalyst. 2. preparation method according to claim 1 is characterized in that: the metal salt of Group IV element described in the step (1) is one or more in the nitrate or chloride of germanium or tin, and the described The metal salt of the Group II element is one or more of the nitrate, chloride or organic acid salt of the metal of the Group II element. 3. preparation method according to claim 1 is characterized in that: the active component of the catalyst described in the step (2) is one or more in platinum group element metal platinum, palladium, iridium, rhbium or osmium The combination; When the above-mentioned active component is platinum, the platinum source used is one or more of chloroplatinic acid, platinum ammonia or oxyplatinum acetylacetonate, and other active components also use corresponding metal chlorides or organic complexes one or more of them. 4 . The preparation method according to claim 1 , wherein the magnesia-aluminum spinel carrier described in step (1) is formed magnesia-aluminum spinel or powdered magnesia-aluminum spinel. 5 . 5. The preparation method according to claim 1, 2 or 3, characterized in that: based on the mass calculation of the magnesia-aluminum spinel carrier, the mass percentage of Group IV element metal in the auxiliary is 0.005 to 3.0wt. %, the mass percentage of Group II element metal is 0.005-6.0 wt.%, and the mass percentage of the active component of the catalyst (eg, metal Pt) is 0.05-1.0 wt.%. 6 . The preparation method according to claim 1 , wherein the mass ratio of the auxiliary group II element metal and the group IV element metal in the step (1) is 0.0005-15.0. 7 . 7 . The preparation method according to claim 1 , wherein the mass ratio of the metal auxiliary agent of the Group IV element and the active component platinum group element metal is 0.0005-2.0. 8 . 8. The preparation method according to claim 1, wherein the drying temperature in the steps (1) and (2) is 100-120°C, the drying time is 4-6h, and the roasting temperature is 450-550°C , the roasting time is 10-12h. 9 . The application of the catalyst prepared by any one of claims 1 to 8 in dehydrogenation of alkanes with a carbon number of less than 5 to produce alkenes.

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