CN113967474A

CN113967474A - Low-carbon alkane dehydrogenation catalyst and preparation method thereof

Info

Publication number: CN113967474A
Application number: CN202010719789.1A
Authority: CN
Inventors: 刘泽超; 刘昌呈; 马爱增; 王春明
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2020-07-24
Filing date: 2020-07-24
Publication date: 2022-01-25
Anticipated expiration: 2040-07-24
Also published as: CN113967474B

Abstract

A low-carbon alkane dehydrogenation catalyst comprises an alumina carrier and the following active components in percentage by weight calculated on the basis of the carrier: 0.02 to 0.1 mass% of platinum and 0.5 to 6 mass% of manganese. The catalyst has low platinum content, is used for preparing olefin by low-carbon alkane dehydrogenation, and has high activity and selectivity.

Description

Low-carbon alkane dehydrogenation catalyst and preparation method thereof

Technical Field

The invention relates to an alkane dehydrogenation catalyst and a preparation method thereof, in particular to a catalyst for preparing olefin by low-carbon alkane dehydrogenation and a preparation method thereof.

Background

Propylene is a basic organic chemical raw material with the largest consumption except ethylene, and propylene products such as polypropylene, acrylonitrile, propylene oxide, propylene ester and the like are closely related to the production and the life of people. The propane dehydrogenation process is an important method for producing propylene, and the Pt-based catalyst and the Cr-based catalyst which are used at present have respective limitations in industrial production.

CN102451677B disclosesThe catalyst for dehydrogenating isobutane comprises MgO and P₂O₅、ZrO₂、Al₂O₃Or SiO₂One or more oxides of the above-mentioned elements are used as carrier, In which the active component A containing one or more oxides of Ti, Nb, Ta, W, Re, In or Ga elements, component C containing one or more oxides of Zn, Cr and Sn and component D containing alkali metal oxide or alkaline earth metal oxide are contained. The continuous reaction-regeneration device is adopted to carry out isobutane dehydrogenation to prepare olefin, the highest isobutene yield can reach 41.60 percent, but the catalyst is easy to deactivate, the manufacturing cost of the reaction device is high, and the loss of the device is large due to the existence of sulfur.

CN103861619A discloses a sulfide catalyst for alkane dehydrogenation, which comprises an active component and a carrier, wherein the active component is one or more of Fe, Co, Ni, Cu, Zn, Mo, W and Mn elements, and the carrier is SiO₂、Al₂O₃、ZrO₂、La₂O₃、CeO₂、CaO、P₂O₅、Nb₂O₅And MgO, the active component on the surface of the alkane dehydrogenation sulfide catalyst exists in a sulfide form. The preparation steps of the catalyst are complex, and the oxidation state catalyst obtained after roasting needs to be presulfurized by hydrogen sulfide.

CN105582929A discloses a catalyst for dehydrogenation reaction of low-carbon alkane and a preparation method thereof, which mainly solve the problems of low activity and poor stability of dehydrogenation catalysts prepared by the prior art. Prepared by using a dipping precipitation method, and comprises the following components: a) 0.1-5 parts of Pt or its oxide; b)0.1 to 5 parts of Sn or an oxide thereof; c)0.1 to 5 parts of an alkali metal or an oxide thereof; d) 0.1-5 parts of Ga, In, Tl, Cr, Mn or oxides thereof; e) 0.1-10 parts of a Ce-La-O solid solution; f) 80-99 parts of carrier Al₂O₃. The catalyst has better performance, but has high cost due to the existence of high content of Pt, and needs to relate to the problems of regeneration of deactivated catalyst, Pt recovery and the like.

CN104936696A discloses a manganese-containing catalyst for dehydrogenation reaction and its preparation method and use, comprising components (A) - (G), (A) is a catalyst substrate, (B) is platinum with a content of 0.5-1.5 wt% of the total amount, (C) is at least one of germanium, tin, lead, gallium, indium and titanium with a content of 0.2-5 wt% of the total amount, (D) is phosphorus with a content of 1-3 wt% of the total amount, (E) is at least one of magnesium, calcium, strontium, barium, radium and lanthanide with a content of 0.1-5 wt% of the total amount, (F) is chloride with a content of 0.1-2 wt% of the total amount, and (G) is manganese. The catalyst is used for the reaction of preparing propylene by propane dehydrogenation, the olefin selectivity is reduced quickly, and the problem of recovery of high-content Pt is also involved.

Disclosure of Invention

The invention aims to provide a low-carbon alkane dehydrogenation catalyst and a preparation method thereof.

The low-carbon alkane dehydrogenation catalyst provided by the invention comprises an alumina carrier and the following active components in content calculated by taking the carrier as a reference:

0.02 to 0.1 mass% of platinum,

0.5 to 6 mass% of manganese.

The low-carbon alkane dehydrogenation catalyst provided by the invention takes low-cost nontoxic manganese as an active component and extremely-low-content platinum as an auxiliary agent, so that the production cost of the catalyst is remarkably reduced, and high catalytic activity is maintained. The catalyst is used for the reaction of preparing olefin by dehydrogenating low-carbon alkane, and has higher conversion rate and selectivity.

Detailed Description

The catalyst of the invention adopts manganese as an active component and a very small amount of platinum as an auxiliary agent, can obviously reduce the cost of the catalyst, keeps higher dehydrogenation conversion rate of low-carbon alkane and selectivity of olefin, and can be recycled.

The catalyst comprises an alumina carrier and active components selected from manganese and platinum, and preferably comprises the following active components:

0.03 to 0.08 mass% of platinum,

1 to 5 mass% of manganese.

The alumina of the invention is preferably gamma-alumina or theta-alumina.

The specific surface area of the alumina is preferably 110-230 m²The pore volume is preferably 0.4-0.7 cm/g³(ii) in terms of/g. When the alumina is gamma-alumina, the specific surface area is preferably 190-220 m²The pore volume is preferably 0.4-0.6 cm/g³(ii)/g; when the alumina is theta-alumina, the specific surface area is preferably 115-120 m²The pore volume is preferably 0.5-0.7 cm/g³/g。

The gamma-alumina carrier can be prepared by a sol-gel method, a coprecipitation method or a hydrothermal synthesis method, and can also be directly prepared by adopting metal oxide. The theta-alumina can be prepared by roasting gamma-alumina at the high temperature of 900-1100 ℃.

The shape of the alumina carrier can be spherical, granular, flake, strip or clover. For the use of a moving bed reactor during the reaction, where continuous regeneration of the catalyst is desired, it is preferred to use a spherical support to facilitate transport of the catalyst during the reaction and regeneration. The average diameter of the spherical alumina carrier is preferably 1.2-2.0 mm.

The lower alkane in the invention is preferably propane, butane or pentane.

The preparation method of the low-carbon alkane dehydrogenation catalyst provided by the invention has two methods, wherein the first method is to prepare manganese-containing alumina by an impregnation method and load platinum; the second method is to prepare manganese-containing alumina by a dropping ball method and then load platinum.

The first preparation method of the low-carbon alkane dehydrogenation catalyst comprises the following steps:

(1) impregnating the alumina with manganese-containing compound solution, wherein the liquid/solid ratio of impregnation is 1.0-2.0 ml/g, then drying and roasting to obtain manganese-containing alumina,

(2) and (2) dipping the manganese-containing alumina prepared in the step (1) by using a platinum-containing compound solution, drying and roasting.

The second preparation method of the low-carbon alkane dehydrogenation catalyst provided by the invention comprises the following steps:

(1) adding manganese-containing compound into aluminum hydroxide sol, stirring uniformly, dropping ball forming, drying, roasting to obtain manganese-containing alumina,

In the above method, the step (1) is to prepare manganese-containing alumina, wherein the manganese-containing compound is preferably manganese acetate, manganese chloride or manganese nitrate.

In the method, the step (2) is to introduce platinum into the manganese-containing alumina, the temperature of the manganese-containing alumina impregnated by the platinum-containing compound solution is preferably 20-70 ℃, and the liquid/solid ratio of impregnation is preferably 1.0-2.0 ml/g. The platinum-containing compound is preferably chloroplatinic acid or ammonium chloroplatinate.

In the first process, the alumina described in the step (1) is preferably γ -alumina or θ -alumina. The alumina carrier used can be spherical, strip-shaped or clover-shaped. The temperature of the aluminum oxide impregnated by the manganese-containing compound solution is preferably 20-70 ℃, and the liquid/solid ratio of the impregnation is preferably 1.0-2.0 ml/g.

In the second method, the method for preparing the aluminum hydroxide sol in step (1) may be various, for example, the aluminum trichloride and the ammonia water are reacted at a temperature of 50 to 90 ℃, preferably 60 to 80 ℃, then filtered, washed, and the acid solution is added to the filter cake to obtain the aluminum hydroxide sol, or the aluminum hydroxide sol can be directly added with water to obtain slurry, and then the acid sol is added to the slurry to obtain the aluminum hydroxide sol. The acid used for peptization is preferably nitric acid or hydrochloric acid, to which organic acids, such as acetic acid or citric acid, may also be added. (1) And (3) roasting the solid obtained after the step of dropping ball forming and drying at the temperature of 450-1100 ℃ so as to form gamma-alumina or theta-alumina. The roasting temperature is preferably 450-650 ℃ when preparing gamma-alumina, and 900-1100 ℃ when preparing theta-alumina.

In the above method, the spherical carrier can be prepared by a dropping ball forming method, such as dropping ball forming by using an oil ammonia column or a hot oil column. The strip-shaped or clover-shaped carrier can be prepared by a conventional extrusion molding method.

In the method, the drying temperature is preferably 100-300 ℃, more preferably 100-140 ℃, and the time is preferably 1-20 hours; the roasting temperature of the solid obtained after the active component is soaked is preferably 500-630 ℃, and the time is preferably 1-20 h.

The catalyst is suitable for the reaction of preparing olefin by dehydrogenating light alkane. The low-carbon alkane and the catalyst are subjected to contact reaction under the conditions of 400-800 ℃, preferably 550-650 ℃, and 0.01-1.0 MPa, preferably 0.01-0.3 MPa (absolute pressure).

In the reaction process, the proper mass space velocity of the low-carbon alkane in contact with the catalyst is 0.1-20 h^-1More preferably 0.5 to 10 hours^-1。

The dehydrogenation reaction can also be carried out by taking steam, argon, methane, ethane, carbon dioxide, nitrogen and the like as diluent materials to be mixed with the low-carbon alkane and then introduced into the reactor, wherein the preferred diluent material is hydrogen. When hydrogen is selected, the molar ratio of the hydrogen to the low-carbon alkane is preferably 0.03-0.5: 1. more preferably 0.1 to 0.5: 1.

the present invention is further illustrated by the following examples, but the present invention is not limited thereto.

Example 1

The catalyst of the present invention is prepared.

(1) Dissolving 0.28g manganese acetate in 30ml deionized water to obtain a soaking solution, and collecting 20.0g manganese acetate with a specific surface area of 210m²Per g, pore volume 0.5cm³gamma-Al of/g₂O₃Pellets, the average diameter of which is 1.6 mm. Subjecting the gamma-Al to₂O₃Placing the pellet in soaking solution, stirring at 25 deg.C for 0.5 hr, standing for 4 hr for soaking at solid/liquid ratio of 1.5g/ml, drying at 120 deg.C for 12 hr, and calcining at 550 deg.C for 10 hr to obtain Mn-containing gamma-Al₂O₃A bead carrier.

(2) Taking the gamma-Al containing Mn₂O₃The pellet carrier was impregnated with a chloroplatinic acid solution as an impregnation solution at 25 ℃ under stirring for 0.5 hour and allowed to stand for 4 hours, with the impregnation solution containing 0.05 mass% of platinum (relative to the alumina carrier) at a liquid/solid ratio of 1.5ml/g, and then dried at 120 ℃ for 12 hours and calcined at 550 ℃ for 10 hours, to obtain catalyst a. The Mn content of the catalyst a calculated on the basis of the carrier was 0.5 mass%, and the Pt content was 0.05 mass%, as follows. The composition and support crystal form of catalyst a are shown in table 1.

Example 2

The catalyst was prepared as in example 1 except that 0.56g of manganese acetate was used in the impregnation solution prepared in step (1) to obtain Mn-containing gamma-Al₂O₃A bead carrier. gamma-Al containing Mn₂O₃And (3) introducing platinum to the pellet carrier according to the method in the step (2) to obtain a catalyst B. The Mn content in the catalyst B was 1 mass%, the Pt content was 0.05 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Example 3

The catalyst was prepared as in example 1, except that manganese acetate was used in the impregnation solution prepared in the step (1) in an amount of 1.13g to obtain Mn-containing gamma-Al₂O₃A bead carrier. gamma-Al containing Mn₂O₃And (3) introducing platinum to the pellet carrier according to the method in the step (2) to obtain a catalyst C. The Mn content of catalyst C was 2 mass%, the Pt content was 0.05 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Example 4

The catalyst was prepared as in example 1 except that manganese acetate was used in the impregnation solution prepared in step (1) at 1.69g to obtain Mn-containing gamma-Al₂O₃A bead carrier. gamma-Al containing Mn₂O₃And (3) introducing platinum to the pellet carrier according to the method in the step (2) to obtain a catalyst D. The Mn content of catalyst D was 3 mass%, the Pt content was 0.05 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Example 5

The catalyst was prepared as in example 1 except that 2.26g of manganese acetate was used in the impregnation solution prepared in step (1) to obtain Mn-containing gamma-Al₂O₃A bead carrier. gamma-Al containing Mn₂O₃And (3) introducing platinum to the pellet carrier according to the method in the step (2) to obtain a catalyst E. The Mn content in the catalyst E was 4 mass%, the Pt content was 0.05 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Example 6

The catalyst was prepared as in example 1 except that manganese acetate was used in the impregnation solution prepared in step (1) at 2.82g to obtain Mn-containing gamma-Al₂O₃A bead carrier. gamma-Al containing Mn₂O₃And (3) introducing platinum to the pellet carrier according to the method in the step (2) to obtain a catalyst F. The catalyst F contained 5 mass% of Mn and 0.05 mass% of Pt%, its composition and carrier crystal form are shown in table 1.

Example 7

A catalyst was prepared by the method of example 1, except that (1) the impregnating solution prepared in step (1) contained 2.26G of manganese acetate, and (2) the impregnating solution containing 0.01 mass% of platinum, and that catalyst G was obtained by drying and calcining. The catalyst G had a Mn content of 4 mass% and a Pt content of 0.01 mass%, and its composition and crystal form of the carrier are shown in table 1.

Example 8

A catalyst was prepared by the method of example 1 except that (1) the impregnating solution prepared in step (1) contained 2.26g of manganese acetate and (2) the impregnating solution for platinum introduction contained 0.03 mass% of platinum, and that catalyst H was obtained by drying and calcining. The Mn content in the catalyst H was 4 mass%, the Pt content was 0.03 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Example 9

A catalyst was prepared by the method of example 1 except that (1) the impregnating solution prepared in step (1) contained 2.26g of manganese acetate and (2) the impregnating solution for platinum introduction contained 0.1 mass% of platinum, and that catalyst I was obtained by drying and calcining. The catalyst I had a Mn content of 4 mass% and a Pt content of 0.1 mass%, and its composition and crystal form of the carrier are shown in table 1.

Example 10

The following examples prepare catalysts by preparing alumina containing manganese by the dropping ball method and then loading platinum.

(1) Taking 26.32g of aluminum hydroxide powder (produced by Sasol company of Germany, brand SB, alumina content 76 mass percent), adding 20ml of deionized water, stirring for 1 hour to make slurry, and then adding 2ml of aluminum hydroxide powder with the volume ratio of 1: 1 to obtain the aluminum sol.

Adding 10ml of aqueous solution containing 6g of urea and 2.26g of manganese acetate into the aluminum sol to ensure that the Mn content in the solution is 4.0 mass percent of dry-based alumina, stirring for 1h, continuing stirring, and dropwise adding 6g of kerosene and 0.6g of fatty alcohol-polyoxyethylene ether into the solution to obtain the sol for dropping balls. Dropping the dropping ball with sol into oil ammonia column with upper oil phase and lower ammonia phase. The oil phase is kerosene, and the concentration of ammonia water in the ammonia water phase is 8 mass%. The wet ball is solidified in ammonia water phase for 1 hour, and is taken out and used with deionized waterWashing, drying at 60 deg.C for 6h, drying at 120 deg.C for 10h, and calcining at 650 deg.C in air for 4h to obtain Mn-containing gamma-Al₂O₃Support, average diameter 1.6 mm.

(2) Taking the gamma-Al containing Mn₂O₃The carrier was impregnated with a chloroplatinic acid solution as an impregnation solution at 25 ℃ for 0.5 hour by stirring and left to stand for 4 hours, the impregnation solution containing 0.05 mass% of platinum (relative to the alumina carrier) at a liquid/solid ratio of 1.5ml/g, and then dried at 120 ℃ for 12 hours and calcined at 550 ℃ for 10 hours, to obtain catalyst J. The Mn content in catalyst J was 4 mass%, the Pt content was 0.05 mass%, and the composition and crystal form of the carrier are shown in table 1.

Example 11

(1) Taking 10.58g of aluminum sheet, adding 240g of hydrochloric acid solution with the concentration of 18 mass% to dissolve the aluminum sheet to obtain a solution with the aluminum trichloride content of 21 mass%, adding 340g of ammonia water with the concentration of 6 mass%, and uniformly mixing at 60 ℃ to obtain a pH value of 7.5-8.5. The generated aluminum hydroxide is filtered and washed, and 4ml of filter cake with the volume ratio of 1: 1 to obtain sol.

Adding 16ml of a solution containing 12g of urea and a solution containing 2.26g of manganese acetate into the sol under stirring to ensure that the Mn content in the solution is 4.0 mass percent of dry-based alumina, stirring for 1h, and then dropwise adding 12g of kerosene and 1.2g of fatty alcohol-polyoxyethylene ether under stirring to obtain the sol for dropping balls.

Dropping the sol into oil ammonia column, forming, drying and roasting to obtain Mn-containing gamma-Al₂O₃Support, average diameter 1.6 mm.

(2) Taking the gamma-Al containing Mn₂O₃The carrier was impregnated with a chloroplatinic acid-containing solution as an impregnation solution at 25 ℃ under stirring for 0.5 hour and allowed to stand for 4 hours, the impregnation solution containing 0.05 mass% of platinum (relative to the alumina carrier) at a liquid/solid ratio of 1.5ml/g, and then dried at 120 ℃ for 12 hours and calcined at 550 ℃ for 10 hours, to obtain catalyst K. The Mn content in catalyst K was 4 mass%, the Pt content was 0.05 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Example 12

(1) Taking the gamma-Al as described in example 1₂O₃The pellet carrier has a water vapor content ofTreating in 5 vol% air for 10h, heating to 1000 deg.C, and calcining for 4h to obtain theta-Al₂O₃Support, obtained theta-Al₂O₃The specific surface area of the support was 118m²Per g, pore volume 0.6cm³The average diameter of the pellets was 1.6 mm/g.

2.26g of manganese acetate was dissolved in 30ml of deionized water to prepare a solution. 20.0g of the above-mentioned theta-Al was taken₂O₃Putting the carrier into the impregnation liquid, stirring for 0.5h, standing for 4h for impregnation, drying at 120 ℃ for 12h, and roasting at 550 ℃ for 10h to obtain the Mn-containing theta-Al₂O₃And (3) a carrier.

(2) Taking the above-mentioned Mn-containing theta-Al₂O₃The carrier was impregnated with a chloroplatinic acid-containing solution as an impregnation solution at 25 ℃ under stirring for 0.5 hour and allowed to stand for 4 hours, the impregnation solution containing 0.05 mass% of platinum (relative to the alumina carrier) at a liquid/solid ratio of 1.5ml/g, followed by drying at 120 ℃ for 12 hours and calcining at 550 ℃ for 10 hours, to obtain a catalyst L. The Mn content in the catalyst L was 4 mass%, the Pt content was 0.05 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Comparative example 1

2.26g of manganese acetate was dissolved in 30ml of deionized water to prepare a solution. 20.0g of gamma-Al as described in example 1 were taken₂O₃And (3) putting the carrier into the impregnation liquid, stirring for 0.5h at 25 ℃, standing for 4h for impregnation, drying for 12h at 120 ℃, and roasting for 10h at 550 ℃ to obtain the catalyst M. The Mn content in the catalyst M was 4 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Comparative example 2

A catalyst N was prepared by following the procedure of example 1, except that the impregnation solution prepared in the step (2) contained 0.5 mass% of platinum, and was dried and calcined. The Mn content in the catalyst N was 4 mass%, the Pt content was 0.5 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Comparative example 3

20.0g of gamma-Al as described in example 1 were taken₂O₃The pellet carrier is impregnated by taking a chloroplatinic acid-containing solution as an impregnation solution, stirring at 25 ℃ for 0.5h, standing for 4h, wherein the impregnation solution contains 0.05 mass percent of platinum (relative to an alumina carrier), the liquid/solid ratio is 1.5ml/g, drying at 120 ℃ for 12h, and roasting at 550 ℃ for 10hTo obtain catalyst O. The Pt content in catalyst O was 0.05 mass%, and the composition and crystal form of the carrier are shown in table 1.

Comparative example 4

The catalyst was prepared by the method of comparative example 3 except that the impregnation solution contained 0.5 mass% of platinum, and the catalyst P was obtained after drying and calcination. The Pt content in catalyst P was 0.5 mass%, and the composition and crystal form of the carrier are shown in table 1.

Comparative example 5

A catalyst R was prepared by the method of comparative example 3, except that the impregnation solution contained 0.1 mass% of platinum, and that the catalyst R was obtained by drying and calcining. The Pt content in the catalyst R was 0.1 mass%, and the composition and crystal form of the carrier are shown in table 1.

Comparative example 6

(1) 2.26g of manganese acetate was dissolved in 30ml of deionized water to prepare a solution. 20.0g of gamma-Al as described in example 1 were taken₂O₃Placing the pellet carrier in the impregnation liquid, stirring for 0.5h, standing for 4h for impregnation, drying at 120 ℃ for 12h, and roasting at 550 ℃ for 10h to obtain Mn-containing gamma-Al₂O₃A bead carrier.

(2) 2.54g of magnesium nitrate was dissolved in 30ml of deionized water to prepare a solution. Mixing the above Mn-containing gamma-Al₂O₃And (3) placing the pellet carrier into the impregnation liquid, stirring for 0.5h, standing for 4h for impregnation, drying at 120 ℃ for 12h, and roasting at 550 ℃ for 10h to obtain the catalyst Q. The Mn content in the catalyst Q was 4 mass%, the Mg content was 3 mass%, and the composition and crystal form of the carrier thereof are shown in table 1.

Examples 13 to 30

In a micro-reactor, 2ml of catalyst is loaded, the mixed gas of hydrogen and propane is used as raw material, the feeding mass space velocity of propane is 9.0h at 600 ℃, 0.1MPa (absolute pressure) and the feeding mass space velocity of propane^-1Hydrogen/propane molar ratio 0.33: 1 for 10 hours, and samples were taken every 0.5 hours for chromatography to calculate the propane conversion and propylene selectivity, and the catalysts used in the examples and the reaction results are shown in table 2.

As can be seen from Table 2, when the platinum content of the catalyst of the present invention is low, manganese has a large promoting effect on the improvement of the catalyst performance. When the Pt loading in the catalyst is greater than 0.1 mass%, the improvement of the catalyst performance by manganese is no longer significant.

TABLE 1

TABLE 2

Claims

1. A low-carbon alkane dehydrogenation catalyst comprises an alumina carrier and the following active components in percentage by weight calculated on the basis of the carrier:

0.02 to 0.1 mass% of platinum,

0.5 to 6 mass% of manganese.

2. The catalyst of claim 1, wherein the catalyst comprises the following active components in amounts:

0.03 to 0.08 mass% of platinum,

1 to 5 mass% of manganese.

3. A catalyst according to claim 1 or 2, characterised in that the alumina is gamma alumina or theta alumina.

4. The catalyst according to claim 1 or 2, characterized in that the lower alkane is propane, butane or pentane.

5. The catalyst according to claim 1 or 2, wherein said alumina support is in the form of spheres having an average diameter of 1.2 to 2.0 mm.

6. A method for preparing the light alkane dehydrogenation catalyst of claim 1, comprising the steps of:

7. A method for preparing the light alkane dehydrogenation catalyst of claim 1, comprising the steps of:

8. The method according to claim 6 or 7, wherein the manganese-containing compound is manganese acetate or manganese nitrate.

9. A method according to claim 6 or 7, characterised in that the platinum containing compound is chloroplatinic acid or ammonium chloroplatinate.

10. The method according to claim 6 or 7, wherein the manganese-containing alumina is impregnated with the platinum-containing compound solution in the step (2) at a temperature of 20 to 70 ℃ in a solid/liquid ratio of 1.0 to 2.0 g/ml.

11. The method according to claim 6 or 7, wherein the drying temperature is 100 to 300 ℃, and the roasting temperature of the solid obtained after the active component is impregnated is 450 to 1100 ℃.

12. The method according to claim 6, wherein the alumina in step (1) is γ -alumina or θ -alumina.

13. The method according to claim 7, wherein the calcination temperature in step (1) is 450 to 1100 ℃ so that γ -alumina or θ -alumina is formed.