CN109647412B - Iron-based catalyst for directly producing low-carbon olefin by synthesis gas - Google Patents

Abstract

The invention relates to an iron-based catalyst for directly producing low-carbon olefin by using synthesis gas, which mainly solves the problem of low selectivity of the low-carbon olefin in the prior art₁₀₀Cu_aCo_bA_cK_dO_xThe technical scheme that A comprises at least one element selected from IIA elements and/or comprises at least one element selected from rare earth elements better solves the problem, and can be used for industrial production of synthesizing low-carbon olefin by fluidized bed synthesis gas.

Description

Iron-based catalyst for directly producing low-carbon olefin by synthesis gas

Technical Field

The invention relates to an iron-based catalyst for directly producing low-carbon olefin by using synthesis gas, a preparation method and application thereof.

Background

The method for converting synthesis gas into hydrocarbons by the action of catalyst is invented by Frans Fischer and Hans Tropsch, German scientists, and is called F-T synthesis for short in 1923, namely the process that CO is subjected to heterogeneous catalytic hydrogenation reaction on a metal catalyst to generate a mixture mainly comprising straight-chain alkane and olefin. Research and development are carried out in the last 20 th century in germany, and industrialization is realized in 1936, and the two-war aftermath is closed because the economy cannot compete with the petroleum industry; south Africa has abundant coal resources, but oil resources are scarce, and are limited by international socioeconomic and political sanctions for a long time, so that the south Africa is forced to develop the coal-to-oil industrial technology, and a first coal-based F-T synthetic oil plant (Sasol-1) with the production capacity of 25-40 ten thousand tons of products per year is built in 1955.

The two global oil crises in 1973 and 1979 caused the price of crude oil in the world to fall and rise greatly, and the F-T synthesis technology re-aroused interest in industrialized countries based on the consideration of strategic technical reserves. In 1980 and 1982, Sasol company in south Africa built and produced two coal-based synthetic oil plants in succession. However, the great reduction of the oil price in the world in 1986 postpones the large-scale industrialization process of the F-T synthesis technology in other countries.

Since the 90 s of the twentieth century, petroleum resources have been in shortage and deterioration, and the exploratory reserves of coal and natural gas have been increasing, so that F-T synthesis technology has attracted much attention again. At present, the main raw materials of the low-carbon olefins in the world are petroleum hydrocarbons, wherein naphtha accounts for most of the raw materials, and alkane, hydrogenated diesel oil, part of heavy oil and the like are also used. Natural gas or light petroleum fractions are mostly used as raw materials at home and abroad, low-carbon olefin is produced by adopting a steam cracking process in an ethylene combination device, the steam cracking is a high-energy consumption device in petrochemical industry, and the steam cracking completely depends on non-renewable petroleum resources, so that alternative resources are urgently needed to be searched along with the gradual shortage of the petroleum resources. Therefore, the research work of preparing olefin by replacing petroleum with other resources is gradually emphasized, and some famous petroleum companies and scientific research institutes in the world perform the research and obtain good results.

Over the course of decades, fischer-tropsch catalysts have also developed in a great deal, and typically comprise the following components: active metals (transition metals of group VIII), oxide supports or structural assistants (SiO)₂,Al₂O₃Etc.), chemical assistants (alkali metal oxides, transition metals) and noble metal assistants (Ru, Re, etc.). Fe produces a large amount of olefins and oxygen-containing compounds, Ru and Co produce mainly long-chain saturated hydrocarbons, and Ni produces mainly methane. Because of the loss of carbonyl compounds easily formed during Ni pressurization reaction and serious methanation, and the expensive Ru and Rh equivalents, the currently commonly used catalysts are divided into two categories from the aspect of active components: iron-based catalysts and cobalt-based catalysts. The selectivity of the cocatalyst to the low-carbon olefin is greatly influenced, and the selectivity of the low-carbon olefin is mainly improved by the cocatalystThe catalyst is realized, and the selection and addition technology of the cocatalyst is one of key technologies for developing excellent catalysts.

The F-T synthesis reactors are further classified into fixed bed reactors, fluidized bed reactors and slurry bed reactors according to the difference in the catalysts used and the difference in the target products. The fixed bed reactor has complex structure, high price, difficult heat removal and lower productivity of the whole device. The slurry bed is characterized by low reaction temperature, easy control, low conversion rate, most of products of high carbon hydrocarbon and difficult liquid-solid separation of slurry in the reactor. The fluidized bed reactor has the characteristics of higher temperature, higher conversion rate, no difficulty of liquid-solid separation and mostly low-carbon hydrocarbon as a product; the lower construction and operating costs, while the lower pressure differential saves a lot of compression costs and facilitates the removal of the heat evolved during the reaction, while the longer run is possible due to the lower gas line speed and less wear problems.

The iron catalyst has many advantages, such as obtaining low-carbon olefin with high selectivity and preparing gasoline with high octane value, and the iron catalyst also has the characteristics of wide operating condition and large product adjustability. The preparation method of the iron-based catalyst mainly comprises three methods: the precipitation method (precipitation catalyst) comprises the steps of preparing a mixed solution by using Fe and auxiliary agents such as Cu, Co, K and the like according to a certain proportion, heating to boil, adding a precipitator, stirring, filtering and washing. Adding water into the obtained filter cake for repulping, adding a certain amount of potassium silicate, drying, carrying out extrusion forming, then, grinding and screening; sintering process (sintering catalyst); oxide mixing method (molten iron catalyst) using mill scale or magnetite powder as raw material and adding Al as auxiliary agent₂O₃MgO, CuO and the like are fed into an electric arc furnace at 1500 ℃ for melting, and the outflow melt is subjected to casting, cooling and multistage crushing.

At present, the iron-based catalyst is used for directly synthesizing low-carbon olefin by F-T in a fixed bed, for example, the patent CN1040397C mentions an iron-based catalyst for Fischer-Tropsch synthesis of low-carbon olefin, and the selectivity of the low-carbon olefin can be as high as 69%. However, the fixed bed reactor has a complex structure, high price, difficult heat removal and low productivity of the whole device. The fluidized bed reactor has the characteristics of higher temperature, higher conversion rate, no difficulty of liquid-solid separation and mostly low-carbon hydrocarbon as a product; the lower construction and operating costs, while the lower pressure differential saves a lot of compression costs and facilitates the removal of the heat evolved during the reaction, while the longer run is possible due to the lower gas line speed and less wear problems. Most of the prior reports on the application of the catalyst to the fluidized bed F-T synthesis are molten iron type catalysts, for example, a molten iron type catalyst for the F-T synthesis is mentioned in patent CN 1704161A; however, the existing fluidized bed F-T synthesis has the problems of insufficiently concentrated products and insufficiently high selectivity of low-carbon olefins.

Disclosure of Invention

One of the technical problems to be solved by the invention is the problem of low selectivity of low-carbon olefin in the prior art, and provides an iron-based catalyst for directly producing low-carbon olefin from synthesis gas, wherein the catalyst has the characteristic of high selectivity of low-carbon olefin.

The second technical problem to be solved by the invention is the application of the catalyst.

The third technical problem to be solved by the invention is a preparation method of the catalyst.

In order to solve one of the above technical problems, the technical solution of the present invention is as follows:

the iron-based catalyst for directly producing the low-carbon olefin by the synthesis gas comprises a carrier and an active component, wherein the active component contains a composition with the following chemical formula in atomic ratio:

Fe₁₀₀Cu_aCo_bA_cK_dO_x

wherein A comprises at least one element selected from IIA elements and/or comprises at least one element selected from rare earth elements;

the value range of a in the formula is 5.0-60.0;

the value range of b is; 1.0 to 30.0;

the value range of c is; 0.1 to 50.0;

the value range of d is 0.1-10.0;

x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst;

the dosage of the carrier is 30-70% of the weight of the catalyst in percentage by weight.

In the above technical scheme, the carrier is not particularly limited, and those commonly used in the art may be used, for example, but not limited to, including at least one of alumina, silica and titania or a mixture thereof.

In the above technical solution, the IIA element preferably includes Mg.

In the above technical scheme, Ce is preferably used as the rare earth element.

In the above technical solutions, as one of more preferable technical solutions, a preferably includes Mg and Ag, and Mg and Ag have a synergistic effect in improving the selectivity of the low-carbon olefin, where a specific chemical formula of the composition is:

Fe₁₀₀Cu_aCo_bMg_1.0～30.0K_dAg_0.1～10.0O_x

in the above technical solution, as a second more preferred technical solution, a preferably includes Ce and Ag, Ce and Ag have a synergistic effect in improving the selectivity of the low-carbon olefin, and at this time, the specific chemical formula of the composition is:

Fe₁₀₀Cu_aCo_bK_dAg_0.1～10.0Ce_0.1～10.0O_x

in the above technical solution, as a third more preferable technical solution, a preferably includes Mg and Ce, and Mg and Ce have a synergistic effect in improving the selectivity of the low-carbon olefin, and at this time, the specific chemical formula of the composition is:

Fe₁₀₀Cu_aCo_bMg_1.0～30.0K_dCe_0.1～10.0O_x

in the above technical solution, as the most preferred technical solution, a simultaneously includes Mg, Ag and Ce, and at this time, Mg, Ag and Ce have a combined synergistic effect in improving the selectivity of low-carbon olefins, and at this time, the specific chemical formula of the composition is:

Fe₁₀₀Cu_aCo_bMg_1.0～30.0K_dAg_0.1～10.0Ce_0.1～10.0O_x。

in the technical scheme, the value range of a is preferably 10.0-50.0. Such as but not limited to 15, 25, 30, 35, 40, 45, etc.

In the technical scheme, the value range of b is preferably 5.0-25.0. Such as but not limited to 6.0, 7.0, 8.0, 10, 12, 15, 20, 25, and the like.

In the technical scheme, the value range of c is preferably 0.1-40.0. Such as, but not limited to, 0.2, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, and the like.

In the technical scheme, the value range of d is 1.0-8.0. Such as but not limited to 1.5, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 7.5, and the like.

The atomic ratio of Mg in the above technical solution is, for example, but not limited to, 1.5, 2.0, 3.0, 5.0, 10, 15, 20, 25, etc

The atomic ratio of Ag in the above technical scheme is, for example, but not limited to, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and the like.

The atomic ratio of Ce in the above technical scheme is, for example, but not limited to, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 60, 7.0, 8.0, 9.0, and the like.

The catalyst used in the reaction for synthesizing the low-carbon olefin can be reduced without reduction, but is preferably reduced. When reducing, the reducing conditions are not particularly limited and can be reasonably selected by the person skilled in the art, for example but not limited to the reducing conditions of the catalyst prepared according to the invention: the pressure is 0.05-5 MPa, preferably 0.1-4 MPa; the reducing gas can be hydrogen, carbon monoxide or synthesis gas, and when the reducing gas is synthesis gas, H thereof₂The mol ratio of/CO is 0.1-6.0, preferably 0.2-6.0; the load of reducing gas is 100-8000 hours^-1Preferably 500 to 6000 hours^-1(ii) a The reduction temperature is 200-600 ℃, preferably 220-500 ℃; the reduction time is 1 to 100 hours, preferably 6 to 72 hours.

For comparison, the reduction conditions used for the catalyst prepared in the embodiment of the present invention are:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

The reduction time was 24 hours.

To solve the second technical problem, the technical solution of the present invention is as follows:

the application of the catalyst in the technical scheme of one of the technical problems in the reaction for directly producing the low-carbon olefin by using the synthesis gas.

The technical key of the present invention is the choice of catalyst, which can be reasonably selected by those skilled in the art for the process conditions of a specific application without inventive effort, such as but not limited to:

in the presence of the catalyst in any of the technical schemes of the technical problems, the synthesis gas reacts to generate the low-carbon olefin.

As known to those skilled in the art, lower olefins are C2-C4 olefins, more specifically ethylene, propylene and butylene or mixtures thereof. The butene includes butene-1, butene-2, isobutene and butadiene.

The reaction temperature can be 200-600 ℃, preferably 220-500 ℃;

the pressure of the reaction can be 0.5-10 MPa, preferably 1-8 MPa; (ii) a

H in synthesis gas₂The mol ratio of/CO can be 0.1-5.0, preferably 0.5-3.0;

the volume space velocity of the synthetic gas can be 100-8000 hours^-1Preferably 500 to 6000 hours^-1More preferably 2000 to 6000 hours^-1。

For the sake of comparability, the evaluation conditions of the catalyst used in the embodiment of the present invention were as follows:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

In order to solve the third technical problem of the invention, the technical scheme of the invention is as follows:

the preparation method of the catalyst in any one of the technical schemes of the technical problems comprises the following process steps:

obtaining an aqueous solution comprising the metallic elements other than K in the composition;

adding sol of a carrier in a required amount into the aqueous solution, adding a KOH solution, and adjusting the pH value of the slurry to 1-6 by using an acid-base regulator to obtain slurry;

feeding the slurry into a spray dryer for spray forming;

and (4) roasting.

In the technical scheme, the roasting temperature is preferably 400-1000 ℃, and more preferably 450-800 ℃.

In the above technical scheme, the roasting time is preferably 0.15 to 10 hours, and more preferably 0.5 to 8 hours.

In the above technical solution, when the composition includes Ce, Mg and Ag at the same time, the preparation method may be embodied as including the following process steps:

(1) dissolving a required amount of soluble ferric salt in water to prepare a solution I,

(2) dissolving required amount of soluble Ce salt in hot water to prepare solution II,

(3) dissolving soluble compounds of Cu, Co, Mg and Ag in water to prepare solution III,

(4) mixing the solution I, the solution II and the solution III to prepare a mixed solution IV,

(5) adding the sol of the carrier with required amount into the solution IV in a water bath at 70-100 ℃, mixing and pulping, simultaneously adding KOH solution, adding an acid-base regulator to regulate the pH value of the slurry to 1-6 to obtain slurry V,

(6) and cooling the slurry V to 20-60 ℃, then sending the slurry V into a spray dryer for spray forming, and then roasting to obtain the iron-based Fischer-Tropsch synthesis catalyst for the microspherical fluidized bed.

The process conditions for spray drying and shaping are not particularly limited and can be appropriately selected by those skilled in the art and can achieve comparable technical effects. For example, but not limited to, the inlet temperature of the spray can be 200-380 ℃, the outlet temperature can be 100-230 ℃, the spray drying is carried out to form microspheres, and finally the microspheres are roasted to prepare the catalyst.

In order to facilitate comparison, the spray drying conditions adopted by the specific embodiment of the invention are as follows:

the inlet temperature is 300 ℃,

the exit temperature was 200 ℃.

In the above technical scheme, the soluble ferric salt can be ferric nitrate or ferric sulfate.

In the above technical scheme, the soluble compounds of Cu, Co, Mg and Ag may be nitrates, salts decomposable into oxides.

In the above-mentioned embodiment, although the atmosphere for firing is not particularly limited, an oxidizing atmosphere or an inert atmosphere is preferable, and an air atmosphere is more preferable from the economical viewpoint.

In the present invention, unless otherwise specified, the pressure including the reaction pressure means a gauge pressure.

The catalyst is used, and the reaction temperature is 200-600 ℃, the reaction pressure is 0.5-10 MPa, and the catalyst load is 100-8000 hours^-1Raw material ratio (mol) H₂The F-T synthesis reaction is carried out under the condition that the ratio of/CO (0.1-5.0): 1, the CO conversion rate can reach 91.8%, the selectivity of low-carbon olefin in a reaction product can reach 71.5%, and a better technical effect is obtained.

The invention is further illustrated by the following examples.

Detailed Description

[ example 1 ]

1. Catalyst preparation

402.40 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolved in 500g of water to give material I, 95.28 g of 50% copper nitrate (Cu (NO) were added₃)₂) 57.40 g of cobalt nitrate (Co (NO)₃)₂·6H₂O) in the same container200g of water is added into the mixture, and the mixture is stirred and dissolved to obtain a material III.

Materials I and III were mixed, 312.50 g of 40 wt% silica sol material was added under stirring, 50g of an aqueous solution containing 2.00 g of KOH was then added, the pH of the slurry was adjusted to 6.0 with 27 wt% aqueous ammonia, and the slurry was stirred sufficiently and then formed into microspheres in a spray dryer, specifically, the spray drying conditions were 300 ℃ at the inlet temperature and 200 ℃ at the outlet temperature of the spray machine. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₃₀Co₂₀K_4.0O_x+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

[ example 2 ]

1. Catalyst preparation

394.90 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolved in 500g of water to give material I, 93.51 g of 50% copper nitrate (Cu (NO) were added₃)₂) 14.90 g of magnesium nitrate (Mg (NO)₃)₄·5H₂O), 56.30 g cobalt nitrate (Co (NO)₃)₂·6H₂O) in the same container, adding 200g of water, stirring and dissolving to obtain a material III.

Materials I and III were mixed, 312.50 g of 40 wt% silica sol material was added under stirring, 50g of an aqueous solution containing 1.97 g of KOH was then added, the pH of the slurry was adjusted to 6.0 with 27 wt% aqueous ammonia, and the slurry was stirred sufficiently and then formed into microspheres in a spray dryer, specifically, the spray drying conditions were 300 ℃ at the inlet temperature and 200 ℃ at the outlet temperature of the spray machine. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₄₀Co₂₀Mg_6.0K_3.0+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

[ example 3 ]

1. Catalyst preparation

391.00 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolved in 500g of water to give material I, 92.59 g of 50% copper nitrate (Cu (NO) were taken₃)₂) 55.80 g of cobalt nitrate (Co (NO)₃)₂·6H₂O) and 9.69 g silver nitrate (AgNO)₃) In the same container, 200g of water is added, and the mixture is stirred and dissolved to obtain a material III.

Materials I and III were mixed, 312.50 g of 40 wt% silica sol material was added under stirring, 50g of an aqueous solution containing 1.95 g of KOH was then added, the pH of the slurry was adjusted with 27 wt% ammonia water so that the pH of the mixed slurry became 6.0, and the slurry after sufficient stirring was subjected to microspherical molding in a spray dryer under the specific conditions of 300 ℃ at the inlet temperature and 200 ℃ at the outlet temperature of a sprayer. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₄₀Co ₂₀K_3.0Ag_6.0+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

[ example 4 ]

1. Catalyst preparation

373.70 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolving with 500g of water to obtain a material I, and taking 23.90 g of cerium nitrate (Ce (NO)₃)₃·6H₂O) was dissolved in 100g of water under heating to obtain a material II, 88.47 g of 50% copper nitrate (Cu (NO)₃)₂) 53.30 g of cobalt nitrate (Co (NO)₃)₂·6H₂O) in the same container, adding 200g of water, stirring and dissolving to obtain a material III.

Materials I, II and III are mixed, 312.50 g of 40 wt% silica sol material is added under stirring, 50g of aqueous solution containing 1.86 g of KOH is then added, the pH value of the slurry is adjusted by using 27 wt% ammonia water so that the pH value of the mixed slurry is 6.0, and the slurry prepared after full stirring is subjected to microspherical molding in a spray dryer, wherein the specific spray drying conditions are that the inlet temperature of a sprayer is 300 ℃ and the outlet temperature is 200 ℃. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₄₀Co₂₀Ce_6.0K_4.0O_x+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

[ example 5 ]

1. Catalyst preparation

382.10 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolving with 500g of water to obtain a material I, and taking 12.20 g of cerium nitrate (Ce (NO)₃)₃·6H₂O) is dissolved in 100g of water under heating to obtain a material II, and 90.48 g of 50% copper nitrate (Cu (NO) is taken₃)₂) 54.50 g of cobalt nitrate (Co (NO)₃)₂·6H₂O) and 4.73 g silver nitrate (AgNO)₃) In the same container, 200g of water is added, and the mixture is stirred and dissolved to obtain a material III.

Materials I, II and III are mixed, 312.50 g of 40 wt% silica sol material is added under stirring, 50g of aqueous solution containing 1.90 g of KOH is then added, the pH value of the slurry is adjusted by using 27 wt% ammonia water so that the pH value of the mixed slurry is 6.0, and the slurry prepared after full stirring is subjected to microspherical molding in a spray dryer, wherein the specific spray drying conditions are that the inlet temperature of a sprayer is 300 ℃ and the outlet temperature is 200 ℃. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₄₀Co₂₀K_3.0Ag_3.0Ce_3.0O_x+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

[ example 6 ]

1. Catalyst preparation

393.00 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolved in 500g of water to give material I, 93.05 g of 50% copper nitrate (Cu (NO) were added₃)₂) 7.40 g of magnesium nitrate (Mg (NO)₃)₄·5H₂O), 57.72 g of cobalt nitrate (Co (NO)₃)₂·6H₂O) and 4.87 g silver nitrate (AgNO)₃) In the same container, 200g of water is added, and the mixture is stirred and dissolved to obtain a material III.

Materials I and III were mixed, 312.50 g of a 40 wt% silica sol material was added under stirring, 50g of an aqueous solution containing 1.96 g of KOH was then added, the pH of the slurry was adjusted with 27 wt% ammonia water so that the pH of the mixed slurry became 6.0, and the slurry after sufficient stirring was subjected to microspherical molding in a spray dryer under specific spray drying conditions of 300 ℃ at the inlet temperature and 200 ℃ at the outlet temperature of a spray machine. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₄₀Co₂₀Mg_3.0K_3.0Ag_3.0O_x+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

[ example 7 ]

1. Catalyst preparation

384.0 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolving with 500g of water to obtain a material I, and taking 12.30 g of cerium nitrate (Ce (NO)₃)₃·6H₂O) was dissolved in 100g of water under heating to obtain a material II, and 90.92 g of 50% copper nitrate (Cu (NO) was added₃)₂) 7.20 g of magnesium nitrate (Mg (NO)₃)₄·5H₂O), 54.80 g of cobalt nitrate (Co (NO)₃)₂·6H₂O) in the same container, adding 200g of water, stirring and dissolving to obtain a material III.

Materials I, II and III are mixed, 312.50 g of 40 wt% silica sol material is added under stirring, 50g of aqueous solution containing 1.91 g of KOH is then added, the pH value of the slurry is adjusted by using 27 wt% ammonia water so that the pH value of the mixed slurry is 6.0, and the slurry prepared after full stirring is subjected to microspherical molding in a spray dryer, wherein the specific spray drying conditions are that the inlet temperature of a sprayer is 300 ℃ and the outlet temperature is 200 ℃. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₄₀Co₂₀Mg_3.0K_3.0Ce_3.0O_x+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

[ example 8 ]

1. Catalyst preparation

385.0 g of ferric nitrate (Fe (NO)₃)₃·9H₂O), dissolving with 500g of water to obtain a material I, and taking 8.20 g of cerium nitrate (Ce (NO)₃)₃·6H₂O) adding 100g of water and heating for dissolving to obtain a materialII, 91.15 g of 50% copper nitrate (Cu (NO)₃)₂) 4.80 g of magnesium nitrate (Mg (NO)₃)₄·5H₂O), 54.90 g of cobalt nitrate (Co (NO)₃)₂·6H₂O) and 3.18 g silver nitrate (AgNO)₃) In the same container, 200g of water is added, and the mixture is stirred and dissolved to obtain a material III.

Materials I, II and III are mixed, 312.50 g of 40 wt% silica sol material is added under stirring, 50g of aqueous solution containing 2.56 g of KOH is then added, the pH value of the slurry is adjusted by using 27 wt% ammonia water so that the pH value of the mixed slurry is 6.0, and the slurry prepared after full stirring is subjected to microspherical molding in a spray dryer, wherein the specific spray drying conditions are that the inlet temperature of a sprayer is 300 ℃ and the outlet temperature is 200 ℃. Finally, the catalyst is calcined in a rotary calcining furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) for 2.0 hours at 500 ℃ in an air atmosphere, and the prepared catalyst comprises the following components:

50% by weight Fe₁₀₀Cu₃₀Co₂₀Mg_2.0K_4.0Ag_2.0Ce_2.0O_x+ 50% by weight of SiO₂

2. Reduction and evaluation of the catalyst

The prepared catalyst is carried out under the reduction conditions:

the temperature is 400 DEG C

Pressure 3.0MPa

Catalyst loading 100g

Catalyst loading 4000 hours^-1

Reducing gas H₂/CO＝2/1

Reduction time 24 hours

Reduction was carried out and then the Fischer-Tropsch synthesis reaction was carried out under the following conditions:

phi 38 mm fluidized bed reactor

The reaction temperature is 330 DEG C

The reaction pressure is 2.0MPa

Catalyst loading 100g

Catalyst loading 3000 hours^-1

Raw material ratio (mol) H₂/CO＝2/1。

The experimental results of the synthesis reaction are shown in table 1.

TABLE 1

Claims (8)

1. The iron-based catalyst for directly producing the low-carbon olefin by the synthesis gas comprises a carrier and an active component, wherein the active component contains a composition with the following chemical formula in atomic ratio:

Fe₁₀₀Cu_aCo_bMg_1.0～30.0K_dAg_0.1～10.0O_xor is or

Fe₁₀₀Cu_aCo_bK_dAg_0.1～10.0Ce_0.1～10.0O_xOr is or

Fe₁₀₀Cu_aCo_bMg_1.0～30.0K_dAg_0.1～10.0Ce_0.1～10.0O_{x ；}

The value range of a in the formula is 5.0-60.0;

the value range of b is 1.0-30.0;

the value range of d is 0.1-10.0;

x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst;

the dosage of the carrier is 30-70% of the weight of the catalyst in percentage by weight.

2. The iron-based catalyst for directly producing low-carbon olefins from synthesis gas according to claim 1, wherein a is in a range of 10.0-50.0.

3. The iron-based catalyst for directly producing low-carbon olefins from synthesis gas according to claim 1, wherein b has a value ranging from 5.0 to 25.0.

4. The iron-based catalyst for directly producing low-carbon olefins from synthesis gas according to claim 1, wherein d is from 1.0 to 8.0.

5. The iron-based catalyst for directly producing the low-carbon olefins from the synthesis gas according to any one of claims 1 to 4, which is characterized in that the iron-based catalyst is reduced before being used for the reaction of directly producing the low-carbon olefins from the synthesis gas.

6. A process for preparing a catalyst as claimed in any of claims 1 to 5, comprising the process steps of:

obtaining an aqueous solution comprising the metallic elements other than K in the composition;

adding sol of a carrier in a required amount into the aqueous solution, adding a KOH solution, and adjusting the pH value of the slurry to 1-6 by using an acid-base regulator to obtain slurry;

feeding the slurry into a spray dryer for spray forming;

and (4) roasting.

7. The method according to claim 6, wherein the calcination temperature is 400 to 1000 ℃.

8. The method according to claim 6, wherein the calcination is carried out for 0.15 to 10 hours.