CN111036284A - Catalyst, preparation method thereof and method for preparing low-carbon olefin from synthesis gas - Google Patents

Abstract

The present disclosure relates to a catalyst, a method for preparing the same, and a method for preparing low carbon olefins from synthesis gas, the catalyst comprising a carrier containing manganese oxide molecular sieve OMS-2 and an active component which is one or more of metal components selected from group VIII metals. Compared with the catalyst in the prior art, the catalyst disclosed by the invention has improved catalytic activity, and can still have higher raw material conversion rate and target product selectivity at high space velocity when being used for preparing low-carbon olefin from synthesis gas.

Description

Catalyst, preparation method thereof and method for preparing low-carbon olefin from synthesis gas

Technical Field

The present disclosure relates to a catalyst, a method of preparing the same, and a method of preparing lower olefins from synthesis gas.

Background

Olefins are important basic chemical raw materials in chemical industry production and also are a mark for measuring the development level of the national petrochemical industry. The worldwide ethylene demand is increased at a rate of 4.1% every year in 1995-2010, and the domestic guarantee capacity is estimated to be 64% by 2750 ten thousand tons of ethylene capacity in China in 2015; meanwhile, the demand of propylene in the world is rapidly increased, the growth rate reaches 6.3% from 2000 to 2010, 2400 million tons of propylene capacity in China are estimated to 2015, the domestic guarantee capacity is 77%, and the olefin supply and demand relationship in China is tense.

The existing methods for preparing low-carbon olefins can be divided into 3 categories according to raw materials: oil routes, natural gas routes, and coal routes. The method for preparing low-carbon olefin by adopting light oil cracking, namely a method for preparing low-carbon olefin by using a petroleum route, is adopted by most countries in the world and accounts for about 65 percent of the yield of olefin. The natural gas is used as a raw material, the technology for preparing the low-carbon olefin by an oxidative coupling method or a Bensen method is adopted, ethylene is mainly used in the product, and the yield of propylene is low. The research of preparing olefin by using coal-based synthesis gas through methanol is rapidly developed, and a plurality of sets of process devices are built in China. In recent years, the demand of three major olefins is continuously increased, and simultaneously, the price of petroleum fluctuates, so that the process cost of olefin taking petroleum and the like as raw materials is increased, the price of the product is increased, and the profit margin of downstream products is reduced. Petroleum routes such as naphtha cracking, paraffin cracking, and the like, have been greatly challenged by conventional petroleum routes. With the increasing shortage of petroleum resources, the increasing price, the increasing cost, and the requirement of sustainable strategic development, large petrochemical companies in developed countries such as the european and american days are actively engaged in developing non-petroleum routes for producing olefins, and among them, chemical technology for producing low-carbon olefins from coal, natural gas, and biomass has attracted increasing attention.

The energy sources in China are in the resource distribution situation of rich coal, much natural gas and oil shortage, and the indirect conversion of coal or natural gas into clean and efficient liquid fuel through Fischer-Tropsch synthesis is an important aspect of reasonably utilizing resources and is also a main technical way for relieving the contradiction between supply and demand of petroleum in China. The process comprises the steps of firstly converting coal or natural gas into synthesis gas, and then preparing liquid fuel or chemical products through Fischer-Tropsch synthesis. The direct preparation of low-carbon olefin from synthesis gas refers to synthesis gas (CO and H)₂) A process for preparing olefins with a carbon number less than or equal to 4 by Fischer-Tropsch synthesis in the presence of a catalyst, by-production of water and CO₂. The Fischer-Tropsch synthesis product distribution is limited by an Anderson-Schulz-Flory rule (the molar distribution of chain growth decreasing by an index), and the strong exothermicity of the reaction is easy to cause the generation of methane and low-carbon alkane, and promote the generated olefin to have secondary reaction, so that the low-carbon olefin is difficult to obtain with high selectivity, and the key point is the development of a high-performance catalyst.

Currently, iron-based catalysts are commonly used in industry to produce olefins in slurry, fixed bed or fluidized bed processes. Under the condition of low-temperature Fischer-Tropsch synthesis process, the product has high heavy hydrocarbon content and low olefin content, and is not beneficial to producing low-carbon olefins. South Africa Sasol company adopts high temperature fluidized bed process to produce gasoline and byproduct low carbon olefin. Although the process can obtain low-carbon number and low-carbon olefin, the yield is low.

The common iron-based Fischer-Tropsch synthesis catalyst is prepared by a coprecipitation method: the active components are precipitated, filtered and washed, then mixed with a carrier, pulped and finally dried and formed, and the active components are applied to a slurry bed reactor, a fixed bed or a fluidized bed reactor. The precipitated iron Fischer-Tropsch synthesis catalyst has poor mechanical stability, easy breakage and serious carbon deposition in the reaction process, and active components in a bulk phase are difficult to reduce. Because the Fischer-Tropsch synthesis is a strong exothermic reaction, the precipitated iron catalyst is difficult to heat in a reactor during the reaction and is easy to fly warm, so that the catalyst is quickly inactivated. Therefore, the supported iron-based catalyst has attracted more and more attention due to its advantages of good stability, uniform distribution of active components, high activity, long service life, and the like. CN1083415A discloses a low-carbon olefin catalyst, which uses an iron-manganese catalyst system carried by alkali metal oxides of IIA group such as MgO and the like or a high-silicon zeolite molecular sieve (or phosphorus-aluminum zeolite), and uses strong alkali K or Cs ions as an auxiliary agent. When the catalyst is used in a fixed bed reactor, although higher CO conversion rate can be obtained in the reaction of preparing low-carbon olefin from synthesis gas, the selectivity of the low-carbon olefin is lower, and the reaction space velocity is lower, which is not beneficial to improving the production efficiency.

Therefore, it is of great practical interest to continue to find new supported catalysts suitable for the production of lower olefins from synthesis gas.

Disclosure of Invention

The purpose of the present disclosure is to provide a catalyst, a preparation method thereof and a method for preparing low carbon olefin from synthesis gas, so as to overcome the defect that the existing catalyst cannot be used at a high space velocity.

To achieve the above object, a first aspect of the present disclosure: a catalyst is provided comprising a support containing manganese oxide molecular sieve OMS-2 and an active component which is one or more of a metal component selected from group VIII metals.

Optionally, the carrier is contained in an amount of 60 to 99.8 wt% based on the dry weight of the catalyst, and the active component is contained in an amount of 0.2 to 40 wt% based on the metal element.

Optionally, the carrier is 70-99.7 wt% based on the dry weight of the catalyst, and the active component is 0.3-30 wt% calculated by metal elements.

Alternatively, the active component is an Fe component, a Ru component, a Pt component, a Co component, a Rh component, a Pd component, or an Ir component, or a combination of two or three thereof.

In a second aspect of the present disclosure: there is provided a process for preparing a catalyst according to the first aspect of the present disclosure, the process comprising:

contacting impregnation liquid containing an active component precursor with the carrier for impregnation, collecting a solid product, drying and roasting;

alternatively, the method comprises:

and (3) reacting the aqueous solution containing the oxidized manganese compound, the reduced manganese compound and the active component precursor at the temperature of 30-180 ℃ for 1-24 h, collecting the solid product, washing, drying and roasting.

Optionally, the impregnation conditions include: the temperature is 10-80 ℃, and preferably 20-60 ℃; the time is 0.1 to 3 hours, preferably 0.5 to 1 hour.

Optionally, the oxidized manganese compound is potassium permanganate or potassium manganate, and the reduced manganese compound is manganese sulfate, manganese nitrate or manganese chloride;

the weight ratio of the oxidized manganese compound to the reduced manganese compound is (1-3): 1.

optionally, the active ingredient precursor is a nitrate, citrate, sulfate or chloride of the active ingredient, or a combination of two or three thereof.

Optionally, the drying conditions include: the temperature is 80-350 ℃, and preferably 100-300 ℃; the time is 1-24 hours, preferably 2-12 hours;

the roasting conditions comprise: the temperature is 250-900 ℃, and preferably 350-800 ℃; the time is 0.5 to 12 hours, preferably 2 to 6 hours.

A third aspect of the disclosure: provided is a method for preparing lower olefins from synthesis gas, comprising the steps of:

(1) carrying out reduction treatment on the initial catalyst in a reducing atmosphere containing hydrogen to obtain a reduced catalyst;

(2) contacting the synthesis gas with the reduced catalyst obtained in the step (1) for reaction;

wherein the initial catalyst is a catalyst according to the first aspect of the present disclosure.

Optionally, in step (1), the reducing conditions include: airspeedIs 1000 to 20000h^-1Preferably 2000 to 10000h^-1(ii) a The temperature is 100-800 ℃, and preferably 200-600 ℃; the time is 0.5-72 h, preferably 1-36 h;

in the step (2), the reaction conditions include: the reaction is carried out in a fluidized bed reactor, the reaction temperature is 300-550 ℃, the reaction pressure is 0.5-8 MPa, and H in the synthesis gas₂The molar ratio of the carbon dioxide to CO is (0.4-2.5): 1, the space velocity of the synthesis gas is 5000-50000 h^-1。

Through the technical scheme, compared with the catalyst in the prior art, the catalyst disclosed by the invention has the advantages that the catalytic activity is improved, and the catalyst can still have higher raw material conversion rate and target product selectivity at high space velocity when being used for preparing low-carbon olefin from synthesis gas.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 is an XRD spectrum of OMS-2, a support prepared in example 9.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

The first aspect of the disclosure: a catalyst is provided comprising a support containing manganese oxide molecular sieve OMS-2 and an active component which is one or more of a metal component selected from group VIII metals.

The inventor of the present disclosure finds in research that the manganese oxide molecular sieve OMS-2 has a mesh tunnel structure, has vacancies capable of loading metals inside, can be substituted by other metal elements for certain framework elements, and has a suitable pore size, strong hydrophobicity, moderate acidity and alkalinity, and strong hydrothermal stability, so that the catalyst prepared by using the manganese oxide molecular sieve OMS-2 as a carrier is particularly suitable for the reaction of preparing low-carbon olefins from synthesis gas, and can effectively improve the conversion rate of raw materials and the selectivity of target products at a high airspeed.

According to the present disclosure, the carrier may be included in an amount of 60 to 99.8 wt% based on the dry weight of the catalyst, and the active component may be included in an amount of 0.2 to 40 wt% in terms of the metal element. In order to further improve the catalytic activity of the catalyst, preferably, the content of the carrier is 70-99.7 wt% based on the dry weight of the catalyst, and the content of the active component is 0.3-30 wt% calculated by metal elements; more preferably, the content of the carrier is 80-98 wt% based on the dry weight of the catalyst, and the content of the active component is 2-20 wt% calculated by metal elements.

Further, the active component may be an Fe component, a Ru component, a Pt component, a Co component, a Rh component, a Pd component, or an Ir component, or a combination of two or three thereof, further an Fe component, a Ru component, or a Co component, or a combination of two or three thereof, and most preferably an Fe component.

In a second aspect of the present disclosure: there is provided a process for preparing a catalyst according to the first aspect of the present disclosure.

In one embodiment of the present disclosure, the active component may be supported on the carrier to obtain the catalyst. Thus, the method may comprise: and (3) contacting impregnation liquid containing an active component precursor with the carrier for impregnation, collecting a solid product, drying and roasting.

In accordance with the present disclosure, manganese oxide molecular sieve OMS-2 may be used as the support either directly or after mixing with a suitable adjuvant (e.g., metals Zr, Cu, Zn, Al, etc.) and using the resulting mixture as the support. Oxides of manganese molecular sieve OMS-2 is commercially available or can be prepared by methods known in the art, and can be prepared, for example, by the steps of: and (3) reacting the aqueous solution containing the oxidized manganese compound and the reduced manganese compound at the temperature of 30-180 ℃ for 1-24 h, collecting the solid product, washing, drying and roasting.

Further, the oxidized manganese compound and the reduced manganese compound are relative; the oxidized manganese compound is generally referred to as containing a relatively high valence state of manganese (e.g., Mn)⁷⁺、Mn⁶⁺Etc.), for example, potassium permanganate or potassium manganate; the reduced manganese compound is generally referred to as containing relatively low levels of manganese (e.g., Mn)²⁺Etc.) and may be, for example, manganese sulfate, manganese nitrate or manganese chloride. In order to achieve the ideal effect, the weight ratio of the oxidized manganese compound to the reduced manganese compound can be (0.1-10): 1. furthermore, in the preparation step, the washing is performed by washing the collected solid product with deionized water until the washing liquid is neutral (for example, pH 6.5 to 7.5). Drying is carried out after washing, and the drying conditions can comprise: the temperature is between room temperature and 200 ℃, preferably between 80 and 150 ℃, and the time is between 1 and 24 hours, preferably between 2 and 12 hours. Then, roasting is carried out, and the roasting conditions can comprise: the temperature is 200-1000 ℃, preferably 300-800 ℃, and more preferably 350-700 ℃; the time is 1-10 h, preferably 2-8 h, and more preferably 3-6 h. Through the steps, pure phase octahedral manganese oxide molecular sieve OMS-2 with XRD spectrogram conforming to JCPDS No.29-1020 can be prepared.

In the above embodiment, the method of the impregnation is not particularly limited, and may be an equivalent-volume impregnation method or a saturation impregnation method. The conditions for the impregnation may be conventional in the art, for example, the conditions for impregnation typically include impregnation: the temperature is 10-80 ℃, and preferably 20-60 ℃; the time is 0.1 to 3 hours, preferably 0.5 to 1 hour. The impregnation liquid is a solution obtained by dissolving an active component precursor in a solvent. Wherein, the solvent can be, for example, water, ethanol, diethyl ether, etc., and the amount of the solvent can be conventional, and the disclosure is not particularly limited.

In another embodiment of the present disclosure, the catalyst can also be prepared by doping the active component with the carrier, i.e., doping the active component during the preparation of the carrier. Thus, the method may comprise: and (3) reacting the aqueous solution containing the oxidized manganese compound, the reduced manganese compound and the active component precursor at the temperature of 30-180 ℃ for 1-24 h, collecting the solid product, washing, drying and roasting.

Wherein, similar to the first embodiment, the oxidized manganese compound and the reduced manganese compound are relative; the oxidized manganese compound is generally referred to as containing a relatively high valence state of manganese (e.g., Mn)⁷⁺、Mn⁶⁺Etc.), for example, potassium permanganate or potassium manganate; the reduced manganese compound is generally referred to as containing relatively low levels of manganese (e.g., Mn)²⁺Etc.) and may be, for example, manganese sulfate, manganese nitrate or manganese chloride. In order to achieve the ideal effect, the weight ratio of the oxidized manganese compound to the reduced manganese compound can be (1-3): 1. the molar ratio of the active component precursor to Mn in the aqueous solution may be 1: (0.1 to 250), preferably 1: (0.5 to 30). Further, the washing is to wash the collected solid product with deionized water until the washing liquid is neutral (for example, pH 6.5 to 7.5). Drying is carried out after washing, and the drying conditions can comprise: the temperature is between room temperature and 200 ℃, preferably between 80 and 150 ℃, and the time is between 1 and 24 hours, preferably between 2 and 12 hours. Then, roasting is carried out, and the roasting conditions can comprise: the temperature is 200-1000 ℃, preferably 300-800 ℃, and more preferably 350-700 ℃; the time is 1-10 h, preferably 2-8 h, and more preferably 3-6 h.

In the above two embodiments, the active component precursor refers to a compound containing the active component, such as nitrate, citrate, sulfate or chloride, or a combination of two or three thereof, which may be the active component; for example, when the active component is an Fe component, the active component precursor may be ferric nitrate, ferric chloride, ferric citrate, or the like.

In the above two embodiments, the carrier and the active component precursor are used in such amounts that the prepared catalyst contains 60 to 99.8 wt%, preferably 70 to 99.7 wt%, of the carrier based on the dry weight of the catalyst, and the active component is 0.2 to 40 wt%, preferably 0.3 to 30 wt%, calculated as the metal element.

In the above two embodiments, the drying and calcining steps are conventional steps in preparing a catalyst, and the disclosure is not particularly limited. For example, the drying conditions may include: the temperature is 80-350 ℃, and preferably 100-300 ℃; the time is 1 to 24 hours, preferably 2 to 12 hours. The conditions for the firing may include: the temperature is 250-900 ℃, preferably 300-850 ℃, and more preferably 350-800 ℃; the time is 0.5 to 12 hours, preferably 1 to 8 hours, and more preferably 2 to 6 hours.

A third aspect of the disclosure: provided is a method for preparing lower olefins from synthesis gas, comprising the steps of:

(1) carrying out reduction treatment on the initial catalyst in a reducing atmosphere containing hydrogen to obtain a reduced catalyst;

(2) contacting the synthesis gas with the reduced catalyst obtained in the step (1) for reaction;

wherein the initial catalyst is a catalyst according to the first aspect of the present disclosure.

According to the disclosure, in the step (1), the catalyst disclosed by the disclosure is subjected to reduction treatment, so that the active component can be subjected to reduction activation, and the catalytic effect of the catalyst can be improved. The conditions of the reduction treatment may include: the airspeed is 1000 ~ 20000h^-1Preferably 2000 to 10000h^-1(ii) a The temperature is 100-800 ℃, preferably 200-600 ℃, and more preferably 250-500 ℃; the time is 0.5 to 72 hours, preferably 1 to 36 hours, and more preferably 2 to 24 hours. The reducing atmosphere can be pure hydrogen atmosphere, or can be a mixed atmosphere of hydrogen and inert gas (such as nitrogen, argon and helium), and the hydrogen partial pressure can be 0.1-4 MPa, preferably 0.1-2 MPa.

According to the present disclosure, the syngas contains CO and H₂And optionally N₂. The synthesis gas is contacted with the supported catalyst for reaction, the ready synthesis gas is contacted with the supported catalyst for reaction, or CO and H are contacted according to the proportion₂Each of which isIntroducing the mixture into a reactor to contact with a catalyst for reaction.

According to the present disclosure, in step (2), the conditions of the reaction may include: the reaction temperature is 300-550 ℃, the reaction pressure is 0.5-8 MPa, and preferably 1-5 MPa; h in the synthesis gas₂The molar ratio of the carbon dioxide to CO is (0.4-2.5): 1, preferably (0.6-2.5): 1, more preferably (0.8 to 2.2): 1; the space velocity of the synthesis gas is 5000-50000 h^-1. In a preferred case, the reaction can be carried out in a fluidized bed reactor. Wherein, the pressure all refers to gauge pressure, and the airspeed all refers to volume airspeed. By mixing CO and H in proportion of synthesis gas₂When the catalyst is respectively introduced into the reactor to contact with the catalyst for reaction, the space velocity of the synthetic gas is CO and H₂The aggregate space velocity of (a).

In the method disclosed by the invention, the reaction for preparing the low-carbon olefin from the synthesis gas can be carried out at a high airspeed, the conversion rate of the raw material carbon monoxide and the selectivity of the target product low-carbon olefin are higher, the reaction condition is mild, the energy consumption is low, and the method is favorable for industrial popularization.

The present disclosure will be described in further detail below by way of examples, but the present disclosure is not limited thereto.

In the following examples and comparative examples:

the content of the active ingredient was measured by X-ray fluorescence spectroscopy RIPP 132-90 (petrochemical analysis (RIPP test method), Yangchini, Kangying, Wu Wenhui ed., first 9 months of 1990, 371-379, Kyun).

Example 1

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 1.16g of ferric nitrate into 3.64g of a 50 wt% manganese nitrate solution, and uniformly stirring to obtain a manganese nitrate solution containing the ferric nitrate, wherein the weight ratio of potassium permanganate to manganese nitrate is 1.7:1, and Fe: and mixing the two solutions with the Mn molar ratio of 1:10, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 24 hours at 180 ℃. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4h to give catalyst a1 prepared in this example, having a composition of 8 wt% Fe-OMS-2 of catalyst a1, calculated as the metal element and based on the dry weight of the catalyst.

Example 2

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 0.58g of ferric nitrate into 3.64g of 50 wt% manganese sulfate solution, and uniformly stirring to obtain a manganese sulfate solution containing the ferric nitrate, wherein the weight ratio of potassium permanganate to manganese sulfate is 1.7:1, Fe: and mixing the two solutions with the Mn molar ratio of 1:20, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 24 hours at 180 ℃. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4 hours to give catalyst a2 prepared in this example, having a composition of 4 wt% Fe-OMS-2 of catalyst a2, calculated as the metal element and based on the dry weight of the catalyst.

Example 3

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 0.25g of ferric nitrate into 3.64g of a 50 wt% manganese nitrate solution, and uniformly stirring to obtain a manganese nitrate solution containing the ferric nitrate, wherein the weight ratio of potassium permanganate to manganese nitrate is 1.7:1, and Fe: and mixing the two solutions with the Mn molar ratio of 1:25, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 24 hours at 180 ℃. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4 hours to give catalyst A3 prepared in this example, having a composition of 3.2 wt% Fe-OMS-2 of catalyst A3, calculated as the metal element and based on the dry weight of the catalyst.

Example 4

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 1.54g of cobalt nitrate into 3.64g of 50 wt% manganese nitrate solution, and uniformly stirring to obtain a Co-containing manganese nitrate solution, wherein the weight ratio of potassium permanganate to manganese nitrate is 1.7:1, Cu: and mixing the two solutions with the Mn molar ratio of 1:12, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 24 hours at 180 ℃. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4 hours to give catalyst a4 prepared in this example, having a composition of 8 wt% Co-OMS-2, calculated as the metal element and based on the dry weight of the catalyst, catalyst a 4.

Example 5

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 1.76g of tetraammineplatinum chloride to 3.64g of a 50 wt% manganese nitrate solution, and uniformly stirring to obtain a manganese nitrate solution containing Pt, wherein the weight ratio of potassium permanganate to manganese nitrate is 1.7:1, and the weight ratio of Pt: the Mn molar ratio is 1: and 9, mixing the two solutions, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction at 180 ℃ for 24 hours. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4h to give catalyst a5 prepared in this example, having a composition of 8 wt% Pt-OMS-2, calculated as the metal element and based on the dry weight of the catalyst, catalyst a 5.

Example 6

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 1.18g of nitrosyl ruthenium nitrate into 3.64g of 50 wt% manganese nitrate solution, and uniformly stirring to obtain a manganese nitrate solution containing Ru, wherein the weight ratio of potassium permanganate to manganese nitrate is 1.7:1, and the weight ratio of Ru: and mixing the two solutions with the Mn molar ratio of 1:13, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 24 hours at 180 ℃. The brown precipitate formed was washed several times with deionized water until the pH of the wash was 7, and the solid product was then dried at 120 ℃ overnight and calcined at 400 ℃ for 4h to give catalyst a6 prepared in this example having a composition of 8 wt.% Ru-OMS-2, calculated as metal element and based on the dry weight of the catalyst, catalyst a 6.

Example 7

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 0.32g of ferric nitrate into 3.64g of a 50 wt% manganese nitrate solution, and uniformly stirring to obtain a manganese nitrate solution containing the ferric nitrate, wherein the weight ratio of potassium permanganate to manganese nitrate is 1.7, Fe: and mixing the two solutions with the Mn molar ratio of 1:110, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction at 180 ℃ for 24 hours. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4 hours to give catalyst a7 prepared in this example, having a composition of 0.5 wt% Fe-OMS-2 of catalyst a7, calculated as the metal element and based on the dry weight of the catalyst.

Example 8

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate to form a potassium permanganate solution, adding 0.16g of ferric nitrate into 3.64g of a 50 wt% manganese nitrate solution, and uniformly stirring to obtain a manganese nitrate solution containing the ferric nitrate, wherein the weight ratio of potassium permanganate to manganese nitrate is 1.7, Fe: and mixing the two solutions with the Mn molar ratio of 1:220, transferring the mixed solution into a hydrothermal reaction kettle, and carrying out hydrothermal reaction for 24 hours at 180 ℃. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4 hours to give catalyst A8 prepared in this example, having a composition of 0.25 wt% Fe-OMS-2 of catalyst A8, calculated as the metal element and based on the dry weight of the catalyst.

Example 9

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate solution to form a potassium permanganate solution, adding 3.64g of a 50 wt% manganese nitrate solution into the potassium permanganate solution, uniformly stirring, transferring the mixture into a hydrothermal reaction kettle, and carrying out hydrothermal reaction at 180 ℃ for 24 hours, wherein the weight ratio of permanganate to manganese nitrate is 1.7: 1. The resulting brown precipitate was washed several times with deionized water until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4 hours to prepare OMS-2 carrier, which had an XRD spectrum as shown in fig. 1 and was found to be pure phase octahedral manganese oxide molecular sieve OMS-2 conforming to JCPDS nos. 29-1020.

Weighing 1.16g of ferric nitrate, dissolving in 10ml of deionized water, stirring uniformly, dropwise adding into 4.15g of the carrier, soaking at 20 ℃ for 1h, drying at 120 ℃ for 5h, and roasting at 400 ℃ for 4h to obtain the catalyst A9 prepared in the embodiment, wherein the catalyst A9 comprises 8 wt% of Fe/OMS-2 in terms of metal elements and based on the dry weight of the catalyst.

Example 10

Dissolving 3.17g of potassium permanganate in 40.55g of deionized water, heating and stirring to dissolve the potassium permanganate solution to form a potassium permanganate solution, adding 3.64g of a 50 wt% manganese nitrate solution into the potassium permanganate solution, uniformly stirring, transferring the mixture into a hydrothermal reaction kettle, and carrying out hydrothermal reaction at 180 ℃ for 24 hours, wherein the weight ratio of permanganate to manganese nitrate is 1.7: 1. The resulting brown precipitate was washed with deionized water several times until the pH of the washing solution became 7, and then the solid product was dried at 120 ℃ overnight and calcined at 400 ℃ for 4h to prepare an OMS-2 carrier.

0.58g of ferric nitrate is weighed, dissolved in 10ml of deionized water, uniformly stirred and then dropwise added into 4.15g of the carrier, the carrier is soaked for 1h at the temperature of 20 ℃, then dried for 5h at the temperature of 120 ℃, and roasted for 4h at the temperature of 400 ℃, so that the catalyst A10 prepared in the embodiment is obtained, and the composition of the catalyst A10 is 4 weight percent of Fe/OMS-2 calculated by metal elements and based on the dry weight of the catalyst.

Test examples

The catalysts prepared in examples 1 to 10 were tested for their catalytic activity in the preparation of lower olefins from synthesis gas.

Charging the initial catalyst into a fluidized bed reactor, and introducing H into the fluidized bed reactor₂The pressure of the reactor is adjusted to be 0.1MPa, and the airspeed is 20000h^-1The temperature is raised to 300 ℃ at the heating rate of 10 ℃/min, and the reduction treatment is carried out at the constant temperature for 4 hours.

After the reduction treatment is finished, the temperature of the reactor is raised to 340 ℃, synthesis gas is introduced to start the reaction, and the space velocity is 10000h^-1The pressure is 1.5MPa, and the composition of the synthesis gas is H₂:CO:N₂The composition of the off-gas was analyzed by on-line gas chromatography at 56:28:16 (volume ratio). The results obtained after 50 hours of reaction are shown in Table 1.

Wherein:

conversion of CO (X)_CO)、CH₄Selectivity of (2)

Selectivity of low carbon olefin

Selectivity of low carbon alkane

And the olefin-alkane molar ratio (O/P) is calculated by the following formulas:

wherein, V₁、V₂Respectively representing the volume of feed gas entering the reaction system and the volume of tail gas flowing out of the reaction system in a certain time period under a standard condition; c. C_1,CO、c_2,CORespectively representing the molar contents of CO in the raw material gas and the tail gas. n is_conIn terms of the number of moles of CO participating in the reaction,

represents the mole number of the low-carbon olefin,

representing the moles of the lower alkane.

TABLE 1

As can be seen from table 1, the catalyst of the present disclosure, when used in a reaction for preparing lower olefins from synthesis gas, has a high carbon monoxide conversion rate and a high lower olefin selectivity in a fluidized bed reactor at a high space velocity.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims (11)

1. A catalyst, characterised in that the catalyst comprises a support comprising manganese oxide molecular sieve OMS-2 and an active component which is one or more of a metal component selected from group VIII metals.

2. The catalyst according to claim 1, wherein the carrier is contained in an amount of 60 to 99.8 wt% based on the dry weight of the catalyst, and the active component is contained in an amount of 0.2 to 40 wt% in terms of the metal element.

3. The catalyst according to claim 2, wherein the carrier is contained in an amount of 70 to 99.7 wt% based on the dry weight of the catalyst, and the active component is contained in an amount of 0.3 to 30 wt% in terms of the metal element.

4. The catalyst of claim 1, wherein the active component is an Fe component, a Ru component, a Pt component, a Co component, a Rh component, a Pd component, or an Ir component, or a combination of two or three thereof.

5. A process for preparing a catalyst according to any one of claims 1 to 4, comprising:

contacting impregnation liquid containing an active component precursor with the carrier for impregnation, collecting a solid product, drying and roasting;

alternatively, the method comprises:

and (3) reacting the aqueous solution containing the oxidized manganese compound, the reduced manganese compound and the active component precursor at the temperature of 30-180 ℃ for 1-24 h, collecting the solid product, washing, drying and roasting.

6. The method of claim 5, wherein the conditions of the impregnation comprise: the temperature is 10-80 ℃, and preferably 20-60 ℃; the time is 0.1 to 3 hours, preferably 0.5 to 1 hour.

7. The method of claim 5, wherein the oxidized manganese compound is potassium permanganate or potassium permanganate and the reduced manganese compound is manganese sulfate, manganese nitrate, or manganese chloride; and/or the presence of a gas in the gas,

the weight ratio of the oxidized manganese compound to the reduced manganese compound is (1-3): 1.

8. the method of claim 5, wherein the active ingredient precursor is a nitrate, citrate, sulfate, or chloride of the active ingredient, or a combination of two or three thereof.

9. The method of claim 5, wherein the drying conditions comprise: the temperature is 80-350 ℃, and preferably 100-300 ℃; the time is 1-24 hours, preferably 2-12 hours; and/or the presence of a gas in the gas,

the roasting conditions comprise: the temperature is 250-900 ℃, and preferably 350-800 ℃; the time is 0.5 to 12 hours, preferably 2 to 6 hours.

10. A process for producing lower olefins from synthesis gas, the process comprising the steps of:

(1) carrying out reduction treatment on the initial catalyst in a reducing atmosphere containing hydrogen to obtain a reduced catalyst;

(2) contacting the synthesis gas with the reduced catalyst obtained in the step (1) for reaction;

wherein the initial catalyst is the catalyst of any one of claims 1 to 4.

11. The method according to claim 10, wherein in step (1), the conditions of the reduction treatment include: the airspeed is 1000 ~ 20000h^-1Preferably 2000 to 10000h^-1(ii) a The temperature is 100-800 ℃, and preferably 200-600 ℃; the time is 0.5-72 h, preferably 1-36 h; and/or the presence of a gas in the gas,

in the step (2), the reaction conditions include: the reaction is carried out in a fluidized bed reactor, the reaction temperature is 300-550 ℃, the reaction pressure is 0.5-8 MPa, and H in the synthesis gas₂The molar ratio of the carbon dioxide to CO is (0.4-2.5): 1, the space velocity of the synthesis gas is 5000-50000 h^-1。

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