CN110508301B

CN110508301B - Biological methanol conversion catalyst SrNiO for full components of methane3/SiC-SiO2-Foam and preparation method thereof

Info

Publication number: CN110508301B
Application number: CN201910808599.4A
Authority: CN
Inventors: 谢君; 张止戈
Original assignee: South China Agricultural University
Current assignee: South China Agricultural University
Priority date: 2019-08-29
Filing date: 2019-08-29
Publication date: 2022-02-22
Anticipated expiration: 2039-08-29
Also published as: CN110508301A

Abstract

The invention relates to a methane full-component conversion biological methanol catalyst SrNiO₃/SiC‑SiO₂-Foam and a process for its preparation. The SrNiO₃/SiC‑SiO₂‑Foam，SrNiO₃Supported SiC-SiO solid support₂on-Foam, SrNiO₃The loading amount of (2-8%). SrNiO prepared by the invention₃/SiC‑SiO₂Foam has a perovskite type unit cell structure, and SrNiO is a perovskite type₃The particles are small, the dispersity is high, the dispersion is uniform, and the problems that the high-load nickel-based catalyst is easy to agglomerate at high temperature and the catalytic performance is limited are solved; reducing the mixture to obtain Ni-SrO/SiC-SiO₂The Foam conversion rate is high, and the methane full-component conversion synthesis gas can be well catalyzed to be applied to the reaction of synthesizing the biological methanol. The preparation method has simple process and low cost, and is easy for industrialized popularization and production.

Description

Biological methanol conversion catalyst SrNiO for full components of methane3/SiC-SiO2-Foam and preparation method thereof

Technical Field

The invention belongs to the technical field of catalysts, and particularly relates to a methane full-component conversion biological methanol catalyst SrNiO₃/SiC-SiO₂-Foam and a process for its preparation.

Background

The energy supply in the world is mainly based on three non-renewable fossil resources, namely coal, petroleum and natural gas. At present, globalization is carried out in the new century, the number of people is rapidly increased, the total amount of economy is rapidly increased, the earth resources are utilized widely, although various resources such as deep sea oil gas, combustible ice, coal bed gas and shale gas can be developed and utilized at present, people also pay attention to the potential shortage problem of non-renewable fossil fuels, and non-renewable natural resources such as petroleum and natural gas are exhausted before 2050, so that the view is consistent and agreed in the whole society. Large quantities of fossil fuelsUse results in atmospheric carbon dioxide (CO)₂) The content is increased year by year, and the greenhouse effect is more and more serious. According to global carbon planning data, the emission of carbon dioxide generated by global fossil fuel combustion in 2013 reaches 360 hundred million tons, and the total emission of carbon dioxide and the emission per capita in China since the last 90 th century show a rapid increase situation. As a main gas causing greenhouse effect, carbon dioxide emission reduction and rational utilization have become global issues. The carbon dioxide emission reduction is not only a pragmatic and social responsibility, and the comprehensive utilization of the carbon dioxide emission reduction has obvious economic benefits. The synthesis gas prepared by reforming methane with carbon dioxide is a carbon dioxide utilization technical route with great development prospect when H is used₂0-0.9% of/CO, CH₄－CO₂Lowest conversion cost, conventional CH₄－CO₂H in synthesis gas produced by reforming₂The ratio of CO/CO is generally more than 3.0, the catalyst is not suitable for the raw materials of oxo-synthesis and production of oxygen-containing organic compounds, and the carbon dioxide partially replaces water to carry out reforming reaction with methane, so that the production cost and the energy consumption can be reduced, and the synthesis gas suitable for Fischer-Tropsch synthesis and methanol production is prepared. Therefore, the technology has great strategic significance for environmental protection and resource utilization, and research work of the technology is concerned by a plurality of researchers.

The synthetic gas refers to a mixed gas of carbon monoxide and hydrogen, and CO and H in the synthetic gas₂The ratio varies with the raw materials and the production method, and the molar ratio is 1/2-3/1. Syngas is one of the organic synthesis feedstocks and is also a source of hydrogen and carbon monoxide, and plays an important role in the chemical industry. The raw materials for the synthesis gas are various, and many carbonaceous resources such as coal, natural gas, petroleum or residual oil, etc. can be used to produce the synthesis gas. The synthesis gas can be converted into liquid and gas fuels, bulk chemicals and fine organic chemical products with high added value. Therefore, the renewable biogas is used as a raw material to replace the synthesis gas, so that the environmental pollution and the greenhouse effect can be effectively reduced, and the development of the high-efficiency catalyst for catalyzing the full-component conversion of the biogas into the synthesis gas has profound significance for the current national conditions of China.

In the reaction of catalyzing the full-component conversion of the biogas to synthesize the biological methanol, the noble metal catalyst such as (Pd and Pt) is widely applied at present, the cost of the noble metal is high, and the application is difficult; therefore, the research and development of the catalyst with low cost, stable performance and good catalytic effect has great application prospect.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of high cost and difficult industrial application of a precious metal catalyst for catalyzing full-component conversion of biogas into synthetic gas for synthesizing biological methanol in the prior art, and provides a perovskite type catalyst SrNiO for full-component conversion of biogas into biological methanol₃/SiC-SiO₂-Foam. The method takes SiC-Foam as a raw material, and generates a layer of SiO on the surface of SiC by calcining₂Film to obtain carrier SiC-SiO₂-Foam; then SrNiO is added₃The perovskite SrNiO is used as a catalytic active component and is enabled to be optimized in loading capacity and calcining conditions₃The catalyst has the advantages of small particles, high dispersibility and uniform dispersion, and avoids the problems of easy agglomeration and limited catalytic performance of the high-load nickel-based catalyst at high temperature. Through further reduction treatment, the obtained Ni-SrO/SiC-SiO₂The Foam conversion rate is high, and the methane full-component conversion synthesis gas can be well catalyzed to be applied to the reaction of synthesizing the biological methanol.

The invention also aims to provide a methane full-component conversion biological methanol catalyst Ni-SrO/SiC-SiO₂-Foam。

Another object of the present invention is to provide the above Ni-SrO/SiC-SiO₂-use of Foam for the preparation of biomethanol.

In order to achieve the purpose, the invention adopts the following technical scheme:

methane full-component conversion biological methanol catalyst SrNiO₃/SiC-SiO₂-Foam，SrNiO₃Supported SiC-SiO solid support₂on-Foam, SrNiO₃The loading amount of the catalyst is 3-7%; the SrNiO₃/SiC-SiO₂Foam is prepared by the following steps:

s1: calcining SiC-Foam for 2-4 h at 900-1050 ℃ in oxygen-containing atmosphere to obtain SiC-SiO₂-Foam；

S2: mixing a strontium source and nickelAdding SiC-SiO after the source is dissolved₂-Foam, crushing, adding chelating agent, performing microwave treatment to obtain gel, and drying to obtain SrNiO₃/SiC-SiO₂-a Foam perovskite-type precursor;

s3: SrNiO is mixed₃/SiC-SiO₂Calcining the-Foam perovskite type precursor for 4-6 h at 700-800 ℃ in an oxygen-containing atmosphere to obtain the SrNiO₃/SiC-SiO₂-Foam。

Research shows that SiO is used as the material₂The high-load nickel-based catalyst which is a carrier has the defects of easy agglomeration and limited catalytic performance at high temperature. And the conventional carriers in industry can cause cold spot problems due to uneven or unstable heat conduction, thereby causing the active components on the carriers to be affected due to the difference of temperature or causing large-area inactivation due to the problem of heat conduction. Thus, the present invention optimizes the high-loading nickel-based catalyst in terms of both the support and the catalyst active component.

On one hand, the invention takes SiC-Foam with strong constraint force of three-dimensional porous structure and cold spot resistance as a carrier main body, and the surface of silicon carbide SiC is oxidized to generate a layer of silicon carbide SiO by high-temperature calcination₂The film and the silicon carbide have the characteristics of uniform heat conduction, high efficiency and the like, and simultaneously the generated SiO₂The membrane can increase the interaction between the active component and the support and thus solve and promote both the cold spot problem and the activity problem encountered during the catalytic reaction process as well as the catalytic activity problem.

In another aspect, the invention uses SrNiO₃As an active component, the material has a perovskite type unit cell structure, and all the nickel strontium elements are arranged in a certain regular order. Simultaneously, the perovskite SrNiO is reduced by hydrogen₃The nickel element in the nickel-based catalyst is orderly separated out, so that the nickel particles are smaller, the dispersity is high, the dispersion is uniform, and the problems that the high-load nickel-based catalyst is easy to agglomerate at high temperature and the catalytic performance is limited are solved.

SrNiO prepared by the invention₃/SiC-SiO₂Foam procatalyst with high elemental confinement, with a regular ordered elemental arrangement as suggested by its perovskite-type unit cell structureAnd the performance is stable. After the reduction, the metal nickel is separated out from the part of the cell which is positioned at the center and has better dispersibility, the strontium element is combined with the residual oxygen element in the cell to form strontium oxide, the effect of strong activated carbon is provided, the carbon deposition is inhibited, and the obtained Ni-SrO/SiC-SiO₂The conversion rate of Foam is high, and the methane full-component conversion synthesis gas can be well catalyzed to be applied to the reaction of synthesizing the biological methanol. The preparation method has simple process and low cost, and is easy for industrialized popularization and production.

Nickel source, strontium source and SiC-SiO₂The amount of Foam may be based on SrNiO₃The load quantity of the power system is adjusted and selected.

SrNiO₃The loading of (A) has an influence on the performance of the catalyst, for example, if the loading is too low, SrNiO₃The mutual synergistic effect of Sr and Ni cannot be achieved due to sparse distribution; too high loading of SrNiO₃Agglomeration easily occurs after too close reduction of the cell distribution due to too close nickel elements. The SrNiO can be further improved by optimizing the loading condition₃/SiC-SiO₂-the catalytic activity of Foam.

It should be understood that the loading refers to the catalytic active ingredient SrNiO₃SrNiO is arranged in the whole catalyst₃/SiC-SiO₂-mass fraction in Foam.

Preferably, the SrNiO₃The loading of (b) was 6%.

Preferably, the calcination in S1 is carried out at a temperature of 1000 ℃ for a time of 3 h.

Preferably, the oxygen-containing atmosphere in S1 is an air atmosphere.

Preferably, the temperature is increased at a temperature increase rate of 3 to 5 ℃/min in S1.

More preferably, the temperature is increased at a temperature increase rate of 5 ℃/min in S1.

Both nickel and strontium sources conventional in the art can be used in the present invention.

Preferably, the nickel source in S2 is Ni (NO)₃)₂Or one or more of nickel acetate.

Preferably, the strontium source in S2 is Sr (NO)₃)₃And/or strontium acetate.

Preferably, the chelating agent in S2 is one or more of citric acid and sodium hydroxide.

Preferably, the molar ratio of the nickel element in the S2 nickel source to the strontium element in the strontium source is 1: 1.

Preferably, the molar ratio of the sum of the nickel element in the nickel source and the strontium element in the strontium source in S2 to the citric acid is 1: 1-3.

Preferably, the calcination in S3 is carried out at a temperature of 750 ℃ for a time of 3 h.

Preferably, the oxygen-containing atmosphere in S3 is an air atmosphere.

Preferably, the temperature is increased at a temperature increase rate of 3 to 5 ℃/min in S3.

More preferably, the temperature is increased at a temperature increase rate of 5 ℃/min in S3.

The invention also claims a methane full-component conversion biological methanol catalyst Ni-SrO/SiC-SiO₂Foam, prepared by the following procedure: the SrNiO is mixed with₃/SiC-SiO₂Reducing the-Foam in a hydrogen atmosphere at 700-850 ℃ to obtain the Ni-SrO/SiC-SiO₂-Foam。

SrNiO₃Is not catalytic active per se to form SrNiO₃The perovskite structure can ensure that nickel and strontium elements are distributed more orderly to form a unified and ordered whole, and the metal nickel is reduced by hydrogen (the reduction is carried out to obtain Ni-SrO/SiC-SiO)₂Foam) has catalytic activity, and the nickel reduced by the unit cell structure is more normative and ordered in distribution, and the distance between the nickel and the unit cell structure is almost constant, so that the catalytic activity of the nickel element can be exerted more, and the catalytic activity is improved without being influenced by other factors such as agglomerated carbon deposition and the like.

Preferably, the reduction time is 1-3 h.

Preferably, the temperature of the reduction is 800 ℃, and the time of the reduction is 2 h.

The above Ni-SrO/SiC-SiO₂The use of Foam for the preparation of biofuels is also within the scope of the invention.

Preferably, the Ni-SrO/SiC-SiO₂-use of Foam for catalyzing full-component conversion of biogas to synthesis gas.

Ni-SrO/SiC-SiO₂Foam can catalyze the conversion of biogas to syngas (CO and H)₂) The synthetic gas can be used as a raw material for synthesizing biofuel methanol.

In general, Ni-SrO/SiC-SiO₂The temperature of Foam in catalyzing the biogas is 750-950 ℃ (normal pressure), wherein 950 ℃ is the best.

Ni-SrO/SiC-SiO₂The amount of Foam used at a catalytic biogas flow rate of 80mL/min was 0.2 g.

Compared with the prior art, the invention has the following beneficial effects:

the method takes SiC-Foam as a raw material, and generates a layer of SiO on the surface of SiC by calcining₂Film to obtain carrier SiC-SiO₂-Foam; then SrNiO is added₃The perovskite SrNiO is used as a catalytic active component and is enabled to be optimized in loading capacity and calcining conditions₃The particles are small, the dispersity is high, the dispersion is uniform, and the problems that the high-load nickel-based catalyst is easy to agglomerate at high temperature and the catalytic performance is limited are solved; through further reduction treatment, the obtained Ni-SrO/SiC-SiO₂The Foam conversion rate is high, and the methane full-component conversion synthesis gas can be well catalyzed to be applied to the reaction of synthesizing the biological methanol.

Drawings

FIG. 1 shows a perovskite catalyst SrNiO₃/SiC-SiO₂-XRD pattern of Foam;

FIG. 2 is a graph of the conversion of methane and carbon dioxide in the reaction products of examples 1-4;

fig. 3 is a graph of the conversion of methane and carbon dioxide in the reaction product of noble metal catalyzed biogas.

Detailed Description

The invention is further illustrated by the following examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention. Experimental procedures without specific conditions noted in the examples below, generally according to conditions conventional in the art or as suggested by the manufacturer; the raw materials, reagents and the like used are, unless otherwise specified, those commercially available from the conventional markets and the like. Any insubstantial changes and substitutions made by those skilled in the art based on the present invention are intended to be covered by the claims.

Examples 1 to 4

This example provides a series of perovskite catalysts SrNiO₃/SiC-SiO₂Foam was prepared by the following method.

1)SiC-SiO₂Preparation of Foam

Calcining SiC-Foam for 3h at 1000 ℃ in air atmosphere to obtain SiC-SiO₂-Foam。

2)SrNiO₃/SiC-SiO₂Preparation of a precursor of the Foam perovskite-type catalyst

Mixing Ni (NO)₃)₂And Sr (NO)₃)₃Dissolving the mixture into 30mL of deionized water according to the corresponding load mass, continuously stirring the mixture, and simultaneously adding a corresponding amount of treated SiC-SiO₂-Foam. And (3) placing the solution in a cell wall breaking pulverizer to process for 30min, adding citric acid with the same molar weight as that of nitrate, and processing for 30min under the microwave condition to form green sol gel. Drying the gel at 110 ℃ for one night to obtain SrNiO₃/SiC-SiO₂-a Foam perovskite precursor. For SrNiO₃/SiC-SiO₂Washing the-Foam perovskite type precursor with water for 3-4 times to make the filtrate neutral, washing with ethanol for three times, and drying in a 35 ℃ oven for 8 hours to obtain SrNiO₃/SiC-SiO₂-a Foam perovskite precursor solid.

The specific addition amount is shown in Table 1 (SrNiO)₃Supported amount of SrNiO₃/(SrNiO₃Mass + SiC-SiO₂-Foam mass)).

TABLE 1 perovskite catalyst SrNiO in examples 1-4₃/SiC-SiO₂Foam and its dose control

3) Perovskite type catalyst SrNiO₃/SiC-SiO₂Preparation of Foam

The obtained SrNiO₃/SiC-SiO₂-preparation of a Foam perovskite precursor by calcination in a muffle furnace under air atmosphere. The temperature rise rate of the calcination is 5 ℃ per minute, the temperature is raised to 750 ℃, and the calcination is carried out for 3 hours. Then cooling to room temperature, adding the obtained solid into water, stirring for 8h at the rotating speed of 600r/min by using a magnetic stirrer, filtering, and washing with ethanol for 3 times. Drying in a 35 ℃ oven for 3h to obtain the perovskite catalyst SrNiO₃/SiC-SiO₂-Foam。

Example 5

This example provides a perovskite catalyst SrNiO₃/SiC-SiO₂Foam, the preparation method of which is substantially identical to that of example 3, with the difference that step 1) of this example prepares SiC-SiO in calcination₂-Foam, the temperature of calcination is 900 ℃ and the time of calcination is 2 h; step 3) in preparation of SrNiO₃/SiC-SiO₂At Foam, the rate of temperature rise of the calcination was 3 ℃ per minute, the temperature of the calcination was 750 ℃ and the time was 4 hours.

Example 6

This example provides a perovskite catalyst SrNiO₃/SiC-SiO₂Foam, the preparation method of which is substantially identical to that of example 3, with the difference that step 1) of this example prepares SiC-SiO in calcination₂-Foam, the temperature of calcination is 1050 ℃, and the time of calcination is 4 h; step 3) in preparation of SrNiO₃/SiC-SiO₂At Foam, the rate of temperature rise of the calcination was 3 ℃ per minute, the temperature of the calcination was 800 ℃ and the time was 6 hours.

Performance testing

(a) characterization

The catalysts prepared in the above examples were characterized by the following means.

1) X-ray diffraction pattern (XRD): as shown in fig. 1.

FIG. 1 shows SrNiO, a perovskite catalyst obtained in example 3₃/SiC-SiO₂XRD of Foam, which shows pure perovskite SrNiO₃Map and SrNiO₃Graph after loadSpectra, their diffraction peaks coincide with those of SiC. List perovskite type catalyst SrNiO₃/SiC-SiO₂XRD pattern of Foam, from which SrNiO can be obtained₃The main diffraction peaks coincide.

Catalytic activity

The perovskite catalyst SrNiO obtained in examples 1 to 4₃0.2g of each of/SiC-SiO 2-Foam was placed in a reactor. Introducing nitrogen for 5-6 times, exhausting air in the reaction kettle, introducing 5% hydrogen for in-situ reduction (reduction at 700-850 ℃ for 1-3 h, specifically at 800 ℃ for 2h to obtain Ni-SrO/SiC-SiO₂Foam), then heating to 750-950 ℃ for reaction, and gas production is carried out after the reaction is stable. The gas chromatography is adopted to detect the produced gas, and the test result is shown in figure 2.

Generally, for the reaction of full-component conversion of biogas to produce synthesis gas, the conversion of methane and carbon dioxide is mainly used. The lower the methane and carbon dioxide content after the reaction, the higher the catalytic activity.

As can be seen from FIG. 2, the SrNiO₃/SiC-SiO₂The Foam perovskite type catalyst catalyzes the methane full-component conversion synthesis gas for synthesizing the biological methanol. As can be seen from the catalytic effects of examples 1-4, the catalytic effects of different load proportions at different temperatures are different, and the load is 2 wt% and the load is changed along with SrNiO at the same temperature₃The conversion rate gradually increases with increasing ratio and with increasing temperature. The conversion reached a maximum at a loading of 6 wt% and the proportional conversions of 6 wt% at 800 ℃ and 850 ℃. With SrNiO₃Different loading capacity, different active sites of the formed crystal, and changed specific surface, when SrNiO₃At a certain time, the active sites of the formed crystals are optimized, thereby producing the best catalytic effect.

In addition, the SrNiO provided in example 3₃/SiC-SiO₂Foam, for example, compared to a Pd, Pt noble metal catalyst. For example, the documents F.Aldoghachi, U.S. Rashid, T.Y.Yun, Rsc Advances 6(2016)10372-10384 disclose that four noble metal catalysts (as shown in Table 2) catalyze the full-component conversion of biogas to produce biogas at the same temperature of 900 deg.CThe results of the synthesis gas tests are shown in FIG. 3 (wherein 1, 2, 3 and 4 represent (1) Pt, Pd, Ni/MgO, (2) Pt, Pd, Ni/Mg, respectively_0.97Ce_0.03 ³⁺O，(3)Pt,Pd,Ni/Mg_0.93Ce_0.07 ³⁺O and (4) Pt, Pd, Ni/Mg_0.85Ce_0.15 ³⁺O))。

TABLE 2 four noble metal catalyst sizes and compositions

As can be seen from fig. 2 and 3, SrNiO provided in the present application₃/SiC-SiO₂Reduction of-Foam to obtain Ni-SrO/SiC-SiO₂The similarity of methane conversion at 900 ℃ with that of noble metal-containing catalysts can also prove that the catalyst is a very potential development direction in the future.

The catalyst provided by the invention has high conversion rate, and can be well used for catalyzing the application of the biogas full-component conversion synthesis gas in the synthesis of the biological methanol.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. Catalyst Ni-SrO/SiC-SiO for full-component conversion synthesis of biogas₂Foam, characterized by Ni-SrO/SiC-SiO₂Foam is prepared by the following procedure: SrNiO is mixed₃/SiC-SiO₂Performing reduction treatment on the Foam at the temperature of 750-850 ℃ in a hydrogen atmosphere to obtain the composite material; SrNiO₃/SiC-SiO₂in-Foam, SrNiO₃Supported SiC-SiO solid support₂on-Foam, SrNiO₃The loading amount of (a) is 2-8 wt.%; the SrNiO₃/SiC-SiO₂Foam is prepared by the following steps:

S2: dissolving strontium source and nickel source, adding SiC-SiO₂-Foam, crushing, adding chelating agent, performing microwave treatment to obtain gel, and drying to obtain SrNiO₃/SiC-SiO₂-a Foam perovskite-type precursor;

s3: SrNiO is mixed₃/SiC-SiO₂Calcining the-Foam perovskite type precursor for 4-6 h at 700-800 ℃ in an oxygen-containing atmosphere to obtain the SrNiO₃/SiC-SiO₂-Foam；

The synthesis gas is H₂And CO, H₂And the volume ratio of the CO to the carbon dioxide is 1-1.2.

2. The methane full-component conversion syngas catalyst Ni-SrO/SiC-SiO according to claim 1₂-Foam, characterized in that said SrNiO₃Loading of (d) was 6 wt.%.

3. The methane full-component conversion syngas catalyst Ni-SrO/SiC-SiO according to claim 1₂-Foam, characterized in that the temperature of the calcination in S1 is 1000 ℃ for 3 h; the oxygen-containing atmosphere in S1 is an air atmosphere.

4. The methane full-component conversion syngas catalyst Ni-SrO/SiC-SiO according to claim 1₂-Foam, characterized in that the nickel source in S2 is Ni (NO)₃)₂Or one or more of nickel acetate; the strontium source in S2 is Sr (NO)₃)₃Or one or more of strontium acetate; the chelating agent in S2 is one or more of citric acid, sodium hydroxide or isopropanol.

5. The methane full-component conversion syngas catalyst Ni-SrO/SiC-SiO according to claim 1₂Foam, characterized in that the molar ratio of nickel element in the S2 nickel source and strontium element in the strontium source is 1: 1.

6. According to claim1 the methane full-component conversion synthesis gas catalyst Ni-SrO/SiC-SiO₂The Foam is characterized in that the molar ratio of the sum of nickel element in the nickel source and strontium element in the strontium source in S2 to citric acid is 1: 1-3.

7. The methane full-component conversion syngas catalyst Ni-SrO/SiC-SiO according to claim 1₂-Foam, characterized in that the temperature of the calcination in S3 is 750 ℃ for 3 h; the oxygen-containing atmosphere in S3 is an air atmosphere.

8. The methane full-component conversion syngas catalyst Ni-SrO/SiC-SiO according to claim 1₂-Foam, characterized in that the temperature of the reduction is 800 ℃ and the time of reduction is 2 h.

9. The catalyst Ni-SrO/SiC-SiO for full-component methane conversion synthesis gas according to any one of claims 1 to 8₂-use of Foam for the preparation of synthesis gas for conversion to biomethanol.