CN109305871B

CN109305871B - Method for producing low-carbon olefin by synthesis gas one-step method

Info

Publication number: CN109305871B
Application number: CN201710628239.7A
Authority: CN
Inventors: 李剑锋; 陶跃武; 庞颖聪; 宋卫林
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2017-07-28
Filing date: 2017-07-28
Publication date: 2021-05-28
Anticipated expiration: 2037-07-28
Also published as: CN109305871A

Abstract

The invention relates to a method for producing low-carbon olefin by a synthesis gas one-step method, which mainly solves the problems of low CO conversion rate and low-carbon olefin selectivity in the reaction of preparing the low-carbon olefin by the synthesis gas one-step method in the prior art. The invention discloses a method for producing low-carbon olefin by adopting a synthesis gas one-step method, which comprises the step of taking the synthesis gas as a raw material, and carrying out contact reaction on the raw material and a catalyst to generate C-containing₂～C₄The catalyst comprises the following components in parts by weight: a)5 to 40 parts of an iron-based element or an oxide thereof; b) 1-20 parts of at least one element in IVB group or oxide thereof; c) 20-70 parts of alpha-alumina; d) 10-40 parts of ZSM-5 type molecular sieve; wherein, the ZSM-5 type molecular sieve is a technical scheme of rare earth modified ZSM-5 molecular sieve, which better solves the problem and can be used for industrial production of preparing low carbon olefin by a synthesis gas one-step method.

Description

Method for producing low-carbon olefin by synthesis gas one-step method

Technical Field

The invention relates to a method for producing low-carbon olefin by using synthesis gas in one step.

Background

The lower olefin is an olefin having 4 or less carbon atoms. The low-carbon olefin represented by ethylene and propylene is a very important basic organic chemical raw material, and the market of the low-carbon olefin is short in supply and demand for a long time along with the rapid growth of the economy of China. At present, the production of low-carbon olefin mainly adopts a petrochemical route of light hydrocarbon (ethane, naphtha and light diesel oil) cracking, and due to the gradual shortage of global petroleum resources and the long-term high-order running of the price of crude oil, the development of the tubular cracking furnace process which only depends on the light hydrocarbon as the raw material in the low-carbon olefin industry encounters larger and larger raw material problems, and the production process and the raw material of the low-carbon olefin need to be diversified. The one-step method for directly preparing the low-carbon olefin from the synthesis gas is a process for directly preparing the low-carbon olefin with the carbon atom number less than or equal to 4 by the Fischer-Tropsch synthesis reaction of carbon monoxide and hydrogen under the action of the catalyst, and the process does not need to further prepare the olefin from the synthesis gas through methanol or dimethyl ether like an indirect process, thereby simplifying the process flow and greatly reducing the investment. At present, the shortage of petroleum resources in China, higher and higher external dependence and the soaring international oil price, the process for preparing olefin by selecting synthesis gas can broaden the raw material sources, and the synthesis gas can be produced by taking crude oil, natural gas, coal and renewable materials as raw materials, so that a substitute scheme can be provided for the technical aspect of steam cracking based on high-cost raw materials such as naphtha. The abundant coal resources and the relatively low coal price in China provide good market opportunities for developing processes for refining coal and preparing low-carbon olefins by using synthesis gas. In the vicinity of the rich oil-gas field of natural gas in China, if the natural gas is low in price, the method is also an excellent opportunity for preparing low-carbon olefin by using the synthesis gas. If the abundant coal and natural gas resources in China can be utilized, the synthesis gas (the mixed gas of carbon monoxide and hydrogen) is prepared by gas making, and the development of the petroleum alternative energy technology for preparing low-carbon olefin from the synthesis gas is bound to have great significance for solving the energy problem in China.

The technology for preparing the low-carbon olefin by the synthesis gas one-step method originates from the traditional Fischer-Tropsch synthesis reaction, the carbon number distribution of the traditional Fischer-Tropsch synthesis product conforms to ASF distribution, and each hydrocarbon has the maximum theoretical selectivity, such as C₂-C₄The maximum selectivity of the fraction is 57%, the gasoline fraction (C)₅-C₁₁) The selectivity of (a) is at most 48%. The greater the value of the chain growth probability α, the greater the selectivity of the product heavy hydrocarbons. Once the alpha value is determined, the selectivity of the overall synthesis product is determined, and the chain growth probability alpha value depends on the catalyst composition, particle size, reaction conditions, and the like. In recent years, it has been found that the product distribution deviates from the ideal ASF distribution due to secondary reactions of olefins caused by re-adsorption of alpha olefins on the catalyst. The Fischer-Tropsch synthesis is a strong exothermic reaction, and a large amount of reaction heat promotes the carbon deposition reaction of the catalyst to generate methane and low-carbon alkane more easily, so that the selectivity of the low-carbon alkene is greatly reduced; secondly, the complex kinetic factors also cause disadvantages for selectively synthesizing the low-carbon olefin; the ASF distribution of the Fischer-Tropsch synthesis product limits the selectivity of synthesizing low-carbon olefin. The catalyst for preparing the low-carbon olefin from the Fischer-Tropsch synthesis gas is mainly an iron catalyst, and can be used for catalyzing Fischer-Tropsch synthesis for improving the selectivity of directly preparing the low-carbon olefin from the synthesis gasThe chemical agent is subjected to physical and chemical modification, for example, a proper pore channel structure of a molecular sieve is utilized, so that the low-carbon olefin can be conveniently diffused away from a metal active center in time, and the secondary reaction of the low-carbon olefin is inhibited; the metal ion dispersibility is improved, and the olefin selectivity is better; the selectivity of the low-carbon olefin can also be improved by changing the interaction between the metal and the carrier; proper transition metal is added, so that the bond energy of the active component and carbon can be enhanced, the generation of methane is inhibited, and the selectivity of low-carbon olefin is improved; the electron promoting assistant is added to promote the increase of CO chemical adsorption heat, the increase of adsorption quantity and the decrease of hydrogen adsorption quantity, so that the selectivity of the low-carbon olefin is increased; eliminating the acid center of the catalyst can inhibit the secondary reaction of the low-carbon olefin and improve the selectivity of the low-carbon olefin. The performance of the catalyst can be obviously improved by the carrier effect of the catalyst carrier and the addition of certain transition metal additives and alkali metal additives, and a novel Fischer-Tropsch synthesis catalyst with non-ASF distribution of products and high activity and high selectivity for preparing low-carbon olefin is developed.

The one-step method for producing low-carbon olefin by using synthesis gas becomes one of the research hotspots for developing Fischer-Tropsch synthesis catalysts. In patent CN1083415A published by institute of chemical and physical sciences in the chinese academy of sciences, an iron-manganese catalyst system supported by an alkali metal oxide of group IIA such as MgO or a high-silicon zeolite molecular sieve (or a phospho-aluminum zeolite) is used, and strong base K or Cs ions are used as an auxiliary agent, so that high activity (90% of CO conversion) and high selectivity (66% of low-carbon olefin selectivity) can be obtained at a reaction temperature of 300-400 ℃ under a reaction pressure of 1.0-5.0 MPa for preparing low-carbon olefin from synthesis gas. However, the preparation process of the catalyst is complex, and particularly, the preparation and forming process of the carrier zeolite molecular sieve has high cost and is not beneficial to industrial production. In the patent application No. 01144691.9 filed by Beijing university of chemical industry, the Fe is prepared by combining laser pyrolysis with solid phase reaction combined technology₃The Fe-based nano catalyst mainly containing C is applied to preparing low-carbon olefin from synthesis gas, and obtains good catalytic effect, the preparation process is relatively complicated due to the need of using a laser pyrolysis technology, and the raw material adopts Fe (CO)₅The catalyst cost is high, and industrialization is difficult. In patent ZL03109585.2 filed by Beijing university of chemical industry, a vacuum impregnation method is adopted to prepare Fe/activated carbon catalyst taking manganese, copper, zinc, silicon, potassium and the like as auxiliary agentsThe catalyst is used for the reaction of preparing low-carbon olefin from synthesis gas, and under the condition of no circulation of raw material gas, the conversion rate of CO is 96 percent, and the selectivity of the low-carbon olefin in hydrocarbon is 68 percent. The iron salt and the auxiliary agent manganese salt used for preparing the catalyst are relatively expensive and relatively difficult to dissolve, and simultaneously, the ethanol is used as a solvent, so that the raw material cost and the operation cost in the catalyst preparation process are inevitably increased. In order to further reduce the cost of the catalyst, in the patent application No. 200710063301.9, the catalyst is prepared by using common medicines and reagents, iron salt is used as ferric nitrate, manganese salt is used as manganese nitrate, potassium salt is used as potassium carbonate, activated carbon is coconut shell carbon, the catalyst needs to be roasted at high temperature and passivated under the protection of flowing nitrogen, special equipment is needed, the preparation process is complex, and the cost is high. And the catalyst has lower CO conversion rate and lower selectivity of the low-carbon olefin in the reaction of preparing the low-carbon olefin from the synthesis gas.

Disclosure of Invention

The invention aims to solve the technical problems of low CO conversion rate and low selectivity of low-carbon olefin in the product in the technology of preparing low-carbon olefin by using the synthesis gas one-step method in the prior art, and provides the method for producing the low-carbon olefin by using the synthesis gas one-step method.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a one-step process for preparing low-carbon olefin from synthetic gas includes such steps as contact reaction between raw material and catalyst to generate C₂～C₄The catalyst comprises the following components in parts by weight:

a)5 to 40 parts of an iron-based element or an oxide thereof;

b) 1-20 parts of at least one element in IVB group or oxide thereof;

c) 20-70 parts of alpha-alumina;

d) 10-40 parts of ZSM-5 type molecular sieve;

wherein the ZSM-5 type molecular sieve is a rare earth modified ZSM-5 molecular sieve.

In the above technical scheme, H in the synthesis gas₂The molar ratio of CO to CO is preferably 1 to 3.

In the technical scheme, the reaction temperature is preferably 250-400 ℃.

In the technical scheme, the reaction pressure is preferably 1.0-3.0 MPa.

In the technical scheme, the volume space velocity of the raw material gas is preferably 500-5000 h^-1。

In the above technical solution, the iron-based element is selected from at least one of iron, cobalt and nickel. The oxide of iron is preferably iron sesquioxide and the oxide of cobalt is preferably cobaltosic oxide.

In the technical scheme, the content of the component a) is preferably 10-30 parts.

In the technical scheme, the content of the component b) is preferably 5-15 parts.

In the technical scheme, the content of the component c) is preferably 30-60 parts.

In the technical scheme, the content of the component d) is preferably 20-30 parts.

In the technical scheme, the silica-alumina ratio SiO of the ZSM-5 type molecular sieve₂/Al₂O₃Preferably 50 to 500. For example, but not limiting of, the silicon to aluminum ratio may be 100, 150, 200, 250, 300, 350, 400, 450, and so forth. For same proportion, the embodiment of the invention partially adopts SiO₂/Al₂O₃A 300 ZSM-5 type molecular sieve.

In the above technical scheme, the component b) preferably further comprises group IIB elements or oxides thereof.

In the above technical solution, the group IIB element preferably includes Zn or an oxide thereof.

In the above technical solution, the IVB element preferably includes Zr or its oxide, and in this case, Zn (or its oxide) and Zr (or its oxide) have a synergistic effect in improving CO conversion rate and selectivity of low-carbon olefin in the product.

The proportions of Zn (or its oxide) and Zr are not particularly limited, and Zn or its oxide is calculated as ZnO, and Zr or its oxide is calculated as ZrO₂In terms of the weight ratio of Zn (or oxide thereof) to Zr (or oxide thereof)But are not limited to 0.51 to 5, more specific non-limiting weight ratios may be 0.61, 0.71, 0.81, 0.91, 1.01, 1.11, 1.21, 1.51, 1.61, 1.71, 1.81, 2.01, 2.11, 2.21, 2.51, 3.01, 3.51, 4.01, 4.51, and the like.

In the above technical scheme, the content of the rare earth element or the oxide thereof in the rare earth modified ZSM-5 molecular sieve is 1-20% by weight, and more specifically, non-limiting content values are 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 15%, and so on.

In the above technical solution, the rare earth element is preferably at least one of lanthanum, gadolinium and samarium or an oxide thereof.

In the above technical solution, the rare earth element is more preferably at least two of lanthanum, gadolinium and samarium or their oxides, and in this case, between two of lanthanum (or its oxide), gadolinium (or its oxide) and samarium (or its oxide), that is, between lanthanum (or its oxide) -gadolinium (or its oxide), lanthanum (or its oxide) -samarium (or its oxide), and gadolinium (or its oxide) -samarium (or its oxide), there is a synergistic effect in improving CO conversion and selectivity of low carbon olefin in the product. The ratio between two rare earth elements (or oxides thereof) at this time is not particularly limited. For example, but not limited to, La and La₂O₃Ga is measured as Gd₂O₃Sm is Sm₂O₃The weight ratio of lanthanum (or its oxide) to gadolinium (or its oxide) may be 0.1-10, and more specific ratio may be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, etc.; the weight ratio of lanthanum (or oxide thereof) to samarium (or oxide thereof) can be 0.1-10, and more specific ratios can be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, and the like; the weight ratio of gadolinium (or its oxide) to samarium (or its oxide) may be 0.1 to 10, and more specifically, the ratio may be, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9,9.5, and so on.

In the technical scheme, the rare earth modified ZSM-5 molecular sieve is prepared by the method comprising the following steps:

(i) dissolving rare earth element salt in water to prepare solution D;

(ii) mixing the solution D with a ZSM-5 hydrogen type molecular sieve to obtain a mixture E;

(iii) and roasting the mixture E to obtain the required modified ZSM-5 molecular sieve.

In the above technical scheme, the preferable range of the calcination temperature in step (iii) is 400-600 ℃.

In the above technical scheme, the preferable range of the calcination time in the step (iii) is 2.0 to 6.0 hours.

In the above technical scheme, the catalyst can be prepared by a method comprising the following steps:

(1) dissolving the salt corresponding to the components a) and b) in water to prepare a solution A;

(2) mixing the solution A with alpha-alumina to obtain a mixture B;

(3) drying and roasting the mixture B to obtain a mixture C;

(4) and mixing the mixture C and the rare earth modified ZSM-5 molecular sieve to obtain the required synthesis gas, and producing the low-carbon olefin by the one-step method.

In the technical scheme, the preferable range of the roasting temperature in the step (3) is 400-800 ℃.

In the technical scheme, the preferable range of the roasting time in the step (3) is 4.0-8.0 hours.

In the above technical solution, the mixing manner in step (ii) and/or step (2) is not particularly required, but the mixing effect is particularly good under vacuum. For example, but not limited to, the solution is impregnated with the corresponding solid component under a vacuum of 1 to 80 kPa.

In the technical scheme, the mixing mode in the step (4) has no special requirement, but the tablet forming and further crushing and screening effects are particularly good after the mixing in the ball mill.

As known to those skilled in the art, the catalyst of the present invention is used in the preparation of C from synthesis gas₂～C₄Before the reaction of the olefin(s) in (b), it is preferable to carry out an on-line reduction treatment step, and the specific reduction conditions can be reasonably selected by those skilled in the art without any inventive step, such as but not limited to the following:

the reduction temperature is 400-500 ℃;

the reducing agent is H₂And/or CO;

the pressure of reduction is normal pressure to 2MPa (measured by gauge pressure);

the volume space velocity of the reducing agent is 1500-6000 hr^-1；

The reduction time is 6-24 hours.

For convenience of comparison, the reduction conditions in the examples of the present invention are:

the temperature is 450 DEG C

Pressure and atmosphere

Catalyst loading 3ml

Volume space velocity of the reducing agent is 4500 hours^-1

Reducing gas H₂

The reduction time was 12 hours.

By adopting the method, the CO conversion rate can reach 99.5 percent, which is improved by 3.5 percent compared with the prior art; the selectivity of the low-carbon olefin in hydrocarbon can reach 78.1 percent, which is 10.1 percent higher than that of the prior art, and a better technical effect is achieved.

Detailed Description

[ example 1 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing the La equivalent to 10 g₂O₃Dissolving lanthanum nitrate hexahydrate in 60 g of deionized water to prepare a solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

Weighing 25 parts by weight of Fe₂O₃Nitric acid nonahydrate ofIron, zinc nitrate hexahydrate equivalent to 10 parts by weight of ZnO, dissolved in 40.0 g of deionized water to prepare a solution a; under the condition of vacuum degree of 80kPa, the solution A is soaked on 40.0 g of alpha-alumina carrier to obtain a mixture B; and drying the impregnated mixture B at 110 ℃, and then roasting at 500 ℃ for 6 hours to obtain a mixture C.

And mixing 75 g of the mixture C and 25 g of the rare earth modified ZSM-5 molecular sieve, grinding and mixing in a ball mill, tabletting for forming, crushing and sieving to obtain particles of 40-80 meshes to obtain the catalyst.

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZnO，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

For convenience of comparison, the composition of the catalyst of the present invention and the evaluation results are shown in Table 1.

[ example 2 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

2. Preparation of the catalyst

Weighing 25 parts by weight of Fe₂O₃Of iron nitrate nonahydrate corresponding to 10 parts by weight of ZrO₂Dissolving the pentahydrate zirconium nitrate into 40.0 g of deionized water to prepare a solution A; under the condition of vacuum degree of 80kPa, the solution A is soaked on 40.0 g of alpha-alumina carrier to obtain a mixture B; and drying the impregnated mixture B at 110 ℃, and then roasting at 500 ℃ for 6 hours to obtain a mixture C.

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 3 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing the amount of 10 g of Gd₂O₃Dissolving gadolinium nitrate hexahydrate in 60 g of deionized water to prepare solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; drying the mixture E at 110 ℃, then roasting at 550 ℃,roasting for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

Weighing 25 parts by weight of Fe₂O₃The iron nitrate nonahydrate and zinc nitrate hexahydrate equivalent to 10 parts by weight of ZnO were dissolved in 40.0 g of deionized water to prepare a solution a; under the condition of vacuum degree of 80kPa, the solution A is soaked on 40.0 g of alpha-alumina carrier to obtain a mixture B; and drying the impregnated mixture B at 110 ℃, and then roasting at 500 ℃ for 6 hours to obtain a mixture C.

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZnO，40％α-Al₂O₃25% modified ZSM-5 (containing Gd)₂O₃ 10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 4 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing the amount of 10 g of Gd₂O₃Dissolving gadolinium nitrate hexahydrate in 60 g of deionized water to prepare solution D; soaking the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 under the condition of the vacuum degree of 80kPa to obtainA mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

Weighing 25 parts by weight of Fe₂O₃Of iron nitrate nonahydrate corresponding to 10 parts by weight of ZrO₂Dissolving the pentahydrate zirconium nitrate into 40.0 g of deionized water to prepare a solution A; under the condition of vacuum degree of 80kPa, the solution A is soaked on 40.0 g of alpha-alumina carrier to obtain a catalyst precursor B; and drying the impregnated catalyst precursor B at 110 ℃, and then roasting at 500 ℃ for 6 hours to obtain a mixture C.

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing Gd)₂O₃ 10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 5 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing 10 g of Sm₂O₃Samarium nitrate hexahydrate dissolved in 60 g to be removedPreparing a solution D from the child water; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZnO，40％α-Al₂O₃25% modified ZSM-5 (containing Sm)₂O₃ 10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 6 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing 10 g of Sm₂O₃Dissolving samarium nitrate hexahydrate in 60 g of deionized water to prepare a solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing Sm)₂O₃10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 7 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

2. Preparation of the catalyst

Weighing 25 parts by weight of Fe₂O₃Iron nitrate nonahydrate, zinc nitrate hexahydrate corresponding to 6 parts by weight of ZnO, and ZrO 4 parts by weight₂Dissolving the pentahydrate zirconium nitrate into 40.0 g of deionized water to prepare a solution A; under the condition of vacuum degree of 80kPa, the solution A is soaked on 40.0 g of alpha-alumina carrier to obtain a mixture B; and drying the impregnated mixture B at 110 ℃, and then roasting at 500 ℃ for 6 hours to obtain a mixture C.

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，6％ZnO，4％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol)) H₂/CO＝2.0/1。

[ example 8 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing the amount of 10 g of Gd₂O₃Dissolving gadolinium nitrate hexahydrate in 60 g of deionized water to prepare solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，6％ZnO，4％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing Gd)₂O₃10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 9 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，6％ZnO，4％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing Sm)₂O₃10％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 10 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing the amount of La equivalent to 5 g₂O₃Lanthanum nitrate hexahydrate corresponding to 5 g of Gd₂O₃Dissolving gadolinium nitrate hexahydrate in 60 g of deionized water to prepare solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZnO，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 5％，Gd₂O₃ 5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 11 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

2. Preparation of the catalyst

Weighing 25 parts by weight of Fe₂O₃Of iron nitrate nonahydrate corresponding to 10 parts by weight of ZrO₂Dissolving zinc nitrate hexahydrate in 40.0 g of deionized water to prepare a solution A; under the condition of vacuum degree of 80kPa, the solution A is soaked on 40.0 g of alpha-alumina carrier to obtain a mixture B; and drying the impregnated mixture B at 110 ℃, and then roasting at 500 ℃ for 6 hours to obtain a mixture C.

To prepare a catalystThe weight percentage is that the following components are contained: 25% Fe₂O₃，10％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 5％，Gd₂O₃ 5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 12 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing the amount of La equivalent to 5 g₂O₃Equivalent to 5 g of Sm in lanthanum nitrate hexahydrate₂O₃Dissolving samarium nitrate hexahydrate in 60 g of deionized water to prepare a solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZnO，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 5％，Sm₂O₃5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 13 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

2. Preparation of the catalyst

Weighing 25 parts by weight of Fe₂O₃Of iron nitrate nonahydrate corresponding to 10 parts by weight of ZrO₂Dissolving the pentahydrate zirconium nitrate into 40.0 g of deionized water to prepare a solution A; the solution A was immersed in 40.0 g of an alpha-alumina carrier under a vacuum of 80kPaObtaining a mixture B; and drying the impregnated mixture B at 110 ℃, and then roasting at 500 ℃ for 6 hours to obtain a mixture C.

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 5％，Sm₂O₃5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 14 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing 5 g of Gd₂O₃Corresponding to 5 g of Sm₂O₃Dissolving samarium nitrate hexahydrate in 60 g of deionized water to prepare a solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZnO，40％α-Al₂O₃25% modified ZSM-5 (containing Gd)₂O₃ 5％，Sm₂O₃5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 15 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing 5 g of Gd₂O₃Corresponding to 5 g of Sm₂O₃Dissolving samarium nitrate hexahydrate in 60 g of deionized water to prepare a solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; drying the mixture E at 110 ℃, and then roasting at 550 DEG CAnd roasting for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，10％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing Gd)₂O₃ 5％，Sm₂O₃5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 16 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

Weighing the amount of La equivalent to 5 g₂O₃Lanthanum nitrate hexahydrate corresponding to 5 g of Gd₂O₃Dissolved in 60 g of deionized waterPreparing a solution D; under the condition of vacuum degree of 80kPa, dipping the solution D on a ZSM-5 hydrogen type molecular sieve with the silica-alumina ratio of 90 g being 200 to obtain a mixture E; and drying the mixture E at 110 ℃, and then roasting at 550 ℃ for 4 hours to obtain the rare earth modified ZSM-5 molecular sieve.

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，6％ZnO，4％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 5％，Gd₂O₃ 5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 17 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，6％ZnO，4％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing La)₂O₃ 5％，Sm₂O₃ 5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst negativeLotus for 4500 hr^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

[ example 18 ]

1. Preparation of rare earth modified ZSM-5 molecular sieve

2. Preparation of the catalyst

The prepared catalyst comprises the following components in percentage by weight: 25% Fe₂O₃，6％ZnO，4％ZrO₂，40％α-Al₂O₃25% modified ZSM-5 (containing Gd)₂O₃ 5％，Sm₂O₃ 5％)。

3. Catalyst evaluation

The evaluation conditions of the catalyst were:

the reaction conditions are as follows:

phi 8 mm fixed bed reactor

The reaction temperature is 325 DEG C

The reaction pressure is 1.5MPa

Catalyst loading 3ml

Catalyst loading 4500 hours^-1

Raw material ratio (mol) H₂/CO＝2.0/1。

TABLE 1

Claims

1. A one-step process for preparing low-carbon olefin from synthetic gas features that the synthetic gas is used as raw material, which is contacted with catalyst to generate C₂～C₄The catalyst comprises the following components in parts by weight:

a) 10-30 parts of iron element or oxide thereof;

b) 5-15 parts of zirconium element or its oxide;

c) 30-60 parts of alpha-alumina;

d) 20-30 parts of ZSM-5 type molecular sieve;

wherein, the ZSM-5 type molecular sieve is a rare earth modified ZSM-5 molecular sieve, and the content of rare earth elements or oxides thereof in the rare earth modified ZSM-5 molecular sieve is 5 to 20 percent by weight; the rare earth element is selected from at least two of lanthanum, gadolinium and samarium or oxides thereof; the lanthanum is La₂O₃Gadolinium is Gd₂O₃Sm is samarium₂O₃The weight ratio of every two elements is 0.5-2;

the catalyst is prepared by the following steps:

(2) mixing the solution A with alpha-alumina to obtain a mixture B;

(3) drying and roasting the mixture B to obtain a mixture C;

(4) and mixing the mixture C with the rare earth modified ZSM-5 molecular sieve to obtain the catalyst.

2. The method for producing low-carbon olefins by using the synthesis gas one-step method as claimed in claim 1, wherein H in the synthesis gas is₂And CO in a molar ratio of 1 to 3.

3. The method for producing the low-carbon olefins by the one-step synthesis gas method according to claim 1, wherein the reaction temperature is 250-400 ℃.

4. The method for producing the low-carbon olefin by the one-step synthesis gas method according to claim 1, wherein the reaction pressure is 1.0-3.0 MPa.

5. The method for producing low-carbon olefins by using the synthesis gas through the one-step method as claimed in claim 1, wherein the volume space velocity of the raw material gas is 500-5000 h^-1。