CN104056629B - A kind of catalyst for low carbon alcohol by synthetic gas, its preparation method and application - Google Patents

Abstract

The invention provides a catalyst for producing low-carbon alcohols from synthesis gas with flake graphite or graphene as a carrier, a preparation method thereof and an application of using the same to prepare low-carbon alcohols. The catalyst is used to synthesize low-carbon alcohols from synthesis gas, and has the characteristics of high conversion rate of CO, good selectivity for alcohols with carbon 2 and above, and good low-temperature activity. The preparation and treatment process are simple and suitable for industrial production. The basic principle of the preparation is to realize the uniform mixing of metal ions in the catalyst precursor, especially copper ions and cobalt ions, by controlling the co-precipitation conditions; due to the strong interaction between the metal and graphite, after reduction, the Cu‑Co nanoalloy It can be highly dispersed on graphite sheets, which can effectively avoid the sintering of CuCo alloy particles due to migration.

Description

A catalyst for producing low-carbon alcohols from syngas, its preparation method and application

technical field

The invention relates to the technical field of chemical catalysts, in particular to a catalyst for producing low-carbon alcohols from synthesis gas, its preparation method and application.

Background technique

With the increasing consumption of petroleum resources, the energy problem is intensifying, and it is imminent to develop a new energy system. The preparation of low-carbon alcohols (referring to alcohols containing two or more carbon atoms) through synthesis gas (CO, H ₂ ) produced from natural gas or coal or renewable biomass resources has attracted great attention, and it is widely used in fuel and chemical industries. The application value is also increasingly prominent. Low-carbon alcohols can be used as high-quality power fuels. As petroleum additives, they can replace the controversial MTBE and the more toxic tetraethyl lead. high in alcohols. In addition, low-carbon alcohol can also be used as one of the means of coal liquefaction to achieve the alkylation and solubilization of coal and as a substitute for liquefied petroleum gas.

The production of low-carbon alcohols from syngas is often accompanied by by-products such as methanol, hydrocarbons, and CO ₂ . Therefore, the key to the synthesis of low-carbon alcohols is to develop catalysts with excellent activity, selectivity and stability. At present, there are four types of catalysts for the synthesis of low-carbon alcohols: noble metal catalysts represented by Rh, modified methanol synthesis catalysts, Mo-based catalysts, and modified FT synthesis catalysts. Among them, although noble metal catalysts represented by Rh have good hydrogenation activity and good alcohol selectivity, their high price and easy poisoning by _CO2 limit their application. The modified methanol synthesis catalyst has harsh operating conditions, and the product is still mainly methanol, so it is gradually eliminated. Although the modified molybdenum-based catalyst has unique sulfur resistance, it can avoid costly deep desulfurization, and the product contains less water and higher content of low-carbon alcohols, but it has strict requirements on the hydrogen-carbon ratio of the feed gas, which must be 1.0 ~1.1, and the catalyst promoter is very easy to form carbonyl compounds with CO, resulting in the loss of its components, so its stability is limited.

The modified Fischer-Tropsch synthesis catalysts are mainly Cu-Fe and Cu-Co based catalysts. In Cu-Fe-based catalysts, due to the high water gas shift reaction activity of Fe, the product contains more water and the selectivity of hydrocarbons is higher. Among the Cu-Co-based catalysts, Co is the most active element in the FT reaction. Co-based catalysts have the advantages of insensitivity to water-gas shift, and are not easy to be poisoned by carbon deposition during the reaction process. Cu is conducive to the formation of alcohols. Cu and Co The synergistic effect of Cu-Co based catalysts can improve the activity of the catalyst and the selectivity of alcohols containing two or more carbon atoms (C2 ₊ alcohols), so Cu-Co-based catalysts are considered to be promising catalysts for the synthesis of low-carbon alcohols. But the selectivity of C ₂₊ alcohol in the reaction product is still on the low side, and has no industrial production value yet.

Currently, the preparation method for the synthesis of CuCo-based catalysts is mainly the impregnation method.

For example, [Journal of Catalysis, 2012, 286:51-61] reported a series of xCuyCo/γ-Al ₂ O ₃ prepared by co-impregnation method (x=0-0.5). When x=y=1, after the calcined product is reduced at a temperature of 673K, copper-cobalt nanoparticles supported by γ-Al ₂ O ₃ are formed. Under the conditions of 2MPa, 523K, and H ₂ /CO ratio of 2:1, the conversion rate of CO is 16.5%, the selectivity of hydrocarbons is 82.6%, and the selectivity of alcohol is 17.1%, among which methanol accounts for 35.7% of the total alcohol content . According to the analysis, the catalyst prepared by this method is generally a mixture of monoclinic structure CuO and spinel structure Co ₃ O ₄ after calcination. After reduction, separate Cu and Co metal particles are obtained, and the active components are unevenly distributed. Thereby weakening the synergy between Cu-Co, which is not conducive to the generation of low-carbon alcohols.

In recent years, layered double hydroxides (LDHs), also known as hydrotalcites, have received great attention, which are composed of positively charged metal hydroxide layers and negatively charged anions between the layers. composed of layered compounds. Its chemical composition can be expressed as [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ (A ^n- ) _x/n mH ₂ O], where M is the metal ion and A ^n- is the interlayer anion. LDHs have unique properties: for example, laminate metal ions can be replaced by other metal ions with similar radii, and have adjustable variability; at the same time, affected by the lattice positioning effect and the minimum lattice energy effect, laminate metal ions can reach the molecular level. Uniform distribution: The thermal decomposition of LDHs has a structural topology effect, which can make the roasted product maintain the characteristics of uniform distribution of the precursor, and further reduction can also form uniformly distributed nano-metal particles or nano-alloy particles. Therefore, the use of LDHs as precursors to prepare catalysts can not only achieve uniform distribution of each component, but also facilitate the synergistic effect between active components.

In the prior art, there is a key problem in Cu-Co bimetallic catalysts: sintering. Due to the high content of Cu-Co, the nano-Cu-Co particles are close to each other, so they are easy to merge into large particles and then deactivate. By adding other components during preparation, such as Zn, Mg, etc., Cu-Co can be diluted to improve anti-sintering, but the dilution is not conducive to the formation of Cu-Co alloy, so the selectivity decreases. Other carriers can also be selected, such as ZrO ₂ , SiO ₂ , etc. to support Cu-Co catalysts, but there are problems such as solid-state reaction between the carrier and Cu-Co and difficulty in preparation.

Contents of the invention

The present invention aims at the technical defects of the prior art, and provides a catalyst for producing low-carbon alcohols from syngas, which uses flake graphite or graphene as a carrier, its preparation method and application.

To achieve the above technical purpose, the present invention adopts the following technical solutions:

A catalyst for producing low-carbon alcohols from syngas, characterized in that it consists of metal components and graphite components, the metal components are mixed components containing Cu, Co, _Al2O3 , and the above _- mentioned components satisfy the following relationship : The mass fraction of graphite components in the total mass of metal components and graphite components is 0.3-30%; the mass fraction of Cu in metal components is 2-25%; the mass fraction of Co in metal components is 3-45%; metal The balance of the components is Al ₂ O ₃ .

Preferably, the metal component also includes an auxiliary agent, the auxiliary agent is a component containing one or more of Zn, Mn, Mg, Ca, Ni, Fe, Cr, and the auxiliary agent is included in the metal component The quality score in is not higher than 70%.

Preferably, the graphite component is obtained by reduction of flaky graphite oxide with a thickness not exceeding 1000 nm.

Preferably, the graphite component is obtained by reduction of flaky graphite oxide with a thickness not exceeding 100 nm.

Preferably, the graphite component is obtained by reducing graphene oxide.

Simultaneously, the present invention also provides a kind of preparation method of above-mentioned catalyst, and its concrete steps are as follows:

1) Mix 98% (w/w) H ₂ SO ₄ , graphite powder, sodium nitrate and potassium permanganate evenly in an ice bath and stirring condition, and then keep it at -5～5℃ for 1～3 hours, then raise the temperature to 30-40°C and keep stirring for 10-180min, then add the first deionized water to it for dilution, keep the temperature of the mixture below 100°C for 1-5h, and then add 30% (w/w) hydrogen peroxide stirring reaction 1～120min, then add the second deionized water wherein to be mixed with and become the mixed solution that graphite concentration is 0.5～20g/L, be graphite oxide, above-mentioned 98% (w/w )H ₂ SO ₄ , graphite powder, sodium nitrate, potassium permanganate, first deionized water, 30% (w/w) hydrogen peroxide mass ratio is (90～95):(1～2.2):( 0.9～1.4):(6～7.5):(130～170):(25～35).

2) Add the above ingredients into deionized water to prepare A mixed solution with a total ion concentration of 0.01-2mol/L is recorded as the first mixed solution; Na ₂ CO ₃ and NaOH are prepared into a second mixed solution, and the molar concentration of NaOH in the second mixed solution is guaranteed to be the same as that of the first mixed solution. The ratio of the sum of the molar concentrations of all cations in the solution is (1-5):1, while ensuring that the ratio of the molar concentrations of _Na2CO3 in the _second mixed solution to the sum of the molar concentrations of all divalent cations in the first mixed solution is (1～5): 1; Add the above-mentioned first mixed solution and the second mixed solution into the graphite oxide obtained in step 1) in parallel, control the pH value to be 8～11, stop when the first mixed solution is added dropwise Add dropwise, and treat the mixture at a temperature of 60-130°C for 6-48 hours, then collect the solid phase and wash until neutral, and then fully dry to obtain a complex;

3) The compound obtained in step 2) is reduced for 0.5 to 6 hours at a temperature of 200 to 600° C. in the presence of a reducing gas with a space velocity of 300 to 8000 h ⁻¹ , so as to obtain the compound used for synthesis gas production. A catalyst for low-carbon alcohols, wherein the reducing gas is a gas containing one or more of hydrogen, carbon monoxide, and methane.

In addition to the above methods, the following methods are also possible:

1) Add graphite powder, sodium nitrate and potassium permanganate to 98% (w/w) H ₂ SO ₄ under ice bath and stirring conditions, mix well and keep it at -5～5℃ for 1～ 3 hours, then raise its temperature to 30-40°C and keep stirring for 10-60min, then add the first deionized water to it for dilution, keep the temperature of the mixture below 100°C for 1-5h during this process, and then add 30 % (w/w) hydrogen peroxide stirring reaction 1～10min, then add the second deionized water wherein to be mixed with and become the mixed solution that graphite concentration is 0.5～20g/L, be graphite oxide solution, above-mentioned 98% (w /w) The mass ratio of H ₂ SO ₄ , graphite powder, sodium nitrate, potassium permanganate, first deionized water, and 30% (w/w) hydrogen peroxide is (90～95):(1～2.2) :(0.9～1.4):(6～7.5):(130～170):(25～35).

2) Add the above ingredients into deionized water to prepare A mixed solution with a total ion concentration of 0.01-2mol/L is recorded as the first mixed solution; Na ₂ CO ₃ and NaOH are prepared into a second mixed solution, and the molar concentration of NaOH in the second mixed solution is guaranteed to be the same as that of the first mixed solution. The ratio of the sum of the molar concentrations of all divalent cations in the solution is (1～5):1, while ensuring that the ratio of the molar concentration of NaOH in the second mixed solution to the sum of the molar concentrations of all divalent cations in the first mixed solution is ( 1～5): 1; the above-mentioned first mixed solution and the second mixed solution are mixed in parallel, and the pH value is controlled to be 8～11. After the first mixed solution is added dropwise, the dropwise addition is stopped, and the mixture is heated at a temperature of 60～ Treat at 130°C for 6 to 48 hours, then add the mixture to the graphite oxide obtained in step 1) and stir thoroughly, then collect the solid phase and wash until neutral, and then fully dry to obtain a composite;

3) The compound obtained in step 2) is reduced for 0.5 to 6 hours at a temperature of 200 to 600° C. in the presence of a reducing gas with a space velocity of 300 to 8000 h ⁻¹ , so as to obtain the compound used for synthesis gas production. A catalyst for low-carbon alcohols, wherein the reducing gas is a gas containing one or more of hydrogen, carbon monoxide, and methane.

For the above two methods, there are the following preferred methods:

Preferably, before step 3) treating the composite with reducing gas, the following step may be further included: roasting the composite under the protection of an inert gas.

The above-mentioned roasting of the composite under the protection of an inert gas can be further preferably the following specific steps: the roasting temperature is 300-800° C., the roasting time is 0.5-10 h, and the inert gas component includes one or more of nitrogen, argon, and helium. kind.

At the same time, the present invention also provides an application of the above-mentioned catalyst for catalyzing synthesis gas to prepare low-carbon alcohols, which includes the following steps: under the condition of contacting with the catalyst for preparing low-carbon alcohols from synthesis gas, the Under the condition of 1-6MPa, the mixed gas of hydrogen and carbon monoxide with a molar ratio of (0.5-3):1 is passed into the reactor at a space velocity of 500-8000 ^-1 .

In the catalyst preparation method of the above technical solution, the thickness of graphite oxide sheet prepared in step 1) is between 1000nm and 1 atomic layer, mainly distributed between 10nm and 100nm.

The above-mentioned technical scheme has the following advantages: the graphite oxide-hydrotalcite-like precursor is prepared by the coprecipitation method, and the nano-copper-cobalt bimetallic catalyst is obtained by reduction. Controlling the precipitation conditions can realize the uniform mixing of various metal ions in the catalyst precursor, especially copper ions and cobalt ions; after reduction, due to the strong interaction between the metal and graphite, Cu-Co nanoalloys can be highly dispersed on graphite flakes/ On the alkene, the sintering of Cu-Co alloy particles can be effectively avoided or slowed down. The Cu-Co active component prepared in this way has a high active specific surface area, and the carrier and additives can inhibit the sintering of the active component. The catalyst has the outstanding advantages of high selectivity for low-carbon alcohols and high low-temperature activity, simple preparation, low cost, and industrial application value.

Description of drawings

Figure 1 is the XRD curve of the catalyst prepared in Example 1 of the present invention after calcination, reduction and reaction, and the XRD is measured by a cobalt target; in the figure: a is the XRD curve of the catalyst precursor after calcination at 500°C ; b is the XRD curve of the catalyst after reduction at 450°C for 3 h; c is the XRD curve of the reduced catalyst after the reaction. * represents the diffraction peak of Co-Cu alloy, ● represents CuCo ₂ O ₄ ;

Figure 2 is the TEM image of the catalyst precursor prepared in Example 1 of the present invention with 5% H ₂ /Ar as the reducing gas, and the temperature is raised to 450 °C at 10 °C/min for 3 hours, and the scale is 2 nm. In the figure, d =0.208nm is the spacing between crystal planes. Since the (111) crystal plane spacing d=0.208nm of Co0.52Cu0.48, this crystal plane belongs to the (111) crystal plane of CuCo alloy;

Fig. 3 is the stability curve of the catalyst prepared in Example 1 of the present invention at a temperature of 255°C; among the figures: curve a is the change trend of the selectivity of alcohols over time; curve b is the change of the conversion rate of CO over time Trend; Curve c is the selectivity of alkanes over time; Curve d is _CO in the product Selectivity over time;

Fig. 4 is a scanning electron microscope image of graphite oxide prepared in Example 1 of the present invention; it can be seen from the figure that the thickness of the graphite sheet is about 30nm.

detailed description

[Example 1]

Add 98% concentrated H ₂ SO ₄ to a dry container, add graphite under stirring in an ice bath, stir, add sodium nitrate, potassium permanganate, and control the temperature of the mixture at 0°C and keep stirring for 2.8 hours; then Keep the mixture at about 31-33°C and stir for 25 minutes; then add deionized water to the mixture to dilute, keep the temperature of the mixture below 100°C during this process, react for 4 hours, take out the reactor, add the first deionized water to dilute, and then Add 30% hydrogen peroxide, stir for 8 minutes; then carry out high-speed centrifugation, wash with deionized water until no SO ₄ ^2- is present in the filtrate, and dry at 80°C for 24 hours to obtain a graphite oxide solution. Add deionized water to prepare a graphite oxide dispersion with a concentration of 7g/L; wherein, the mass ratio of each reactant is 98% concentrated H ₂ SO ₄ : graphite: sodium nitrate: potassium permanganate: the first deionized water : 30% hydrogen peroxide = 92:2:1:7:150:33.

The molar ratio of copper nitrate, cobalt nitrate and aluminum nitrate is 2:4:3 to prepare a mixed salt solution with a total metal concentration of 1mol/L, which is recorded as solution A; according to c(Na ₂ CO ₃ )=0.66mol/L and c(NaOH)=4.1mol/L to form a mixed alkali solution and denote it as B. The volume of solution A and solution B is 1. Add solution A and solution B into the reactor containing the above-mentioned graphite oxide dispersion in parallel, and control the pH value to 9.5. After the solution A is added dropwise, age for 12 hours at a temperature of 80°C, and the product is separated from the solid and liquid Wash until neutral, and dry at 80°C for 24 hours to obtain a composite of hydrotalcite-like precursor and graphite oxide;

Put the catalyst precursor prepared by the above method into a muffle furnace, roast at a temperature of 500° C. in a nitrogen atmosphere for 4 h, take the roasted product into a reactor, and feed into the reactor _H2 with a volume fraction of 5% hydrogen, Argon mixed gas, raised to 450° at a heating rate of 10°C/min for 3h reduction, naturally cooled to room temperature, then introduced a synthesis gas with a molar ratio of _H2 and CO of 2:1, and raised the pressure to 3MPa, the synthesis gas The volumetric space velocity is set to 3900h ^-1 , and the temperature is set to 240°C-300°C. The SP3410 gas chromatograph was used for on-line testing, and the conversion rate of CO and the distribution of each product as a function of temperature are shown in Table 1. It can be seen that both the CO conversion rate and the low-carbon alcohol selectivity are high.

From the XRD pattern of the catalyst precursor prepared by the above method after reduction, it can be seen that the alloy diffraction peak appears after the catalyst precursor is reduced, indicating that an alloy is formed, and the size of the alloy is calculated by the Scherrer formula to be between 3-10nm. There are still alloy diffraction peaks in the XRD after the reaction, indicating that the CuCo alloy exists stably without phase separation, which directly indicates that the catalyst has good stability.

Table 1

[Example 2]

The preparation method of graphite oxide is identical with embodiment 1.

The molar ratio of copper nitrate, cobalt nitrate, zinc nitrate and aluminum nitrate is 2:2:1:3 to prepare a mixed salt solution with a total metal concentration of 1mol/L, which is recorded as solution A; according to c(Na ₂ CO ₃ ) =1.0mol/L and c(NaOH)=3.2mol/L are made into mixed alkali solution and denoted as B. The volume consumption of solution A and solution B is 1.3. Add solution A and solution B into a 1.5L reactor with a concentration of 3g/L graphite oxide dispersion in parallel, and control the pH value to 9.7. After the solution A is added dropwise, age for 12 hours at a temperature of 60°C. The product was washed to neutral after solid-liquid separation, and dried at a temperature of 80°C for 14 hours to obtain a composite of hydrotalcite-like precursor and graphite oxide;

Put the catalyst precursor prepared by the above method into a muffle furnace, roast at a temperature of 550° C. in a nitrogen atmosphere for 3 h, take the roasted product into a reactor, and feed into the reactor _H2 with a volume fraction of 5% hydrogen, Argon mixed gas, raised to 450° at a heating rate of 5°C/min and reduced for 3 hours, cooled naturally to room temperature, and fed into a synthesis gas with a molar ratio of _H2 and CO of 2:1 to raise the pressure to 3MPa, and the synthesis gas The volumetric space velocity is set to 3900h ^-1 , and the temperature is set to 290°C. The SP3410 gas chromatograph was used for online testing, and the conversion rate of CO and the distribution of each product are shown in Table 2.

[Example 3]

The preparation method of graphite oxide is identical with embodiment 1.

According to the molar ratio of copper nitrate, cobalt nitrate, calcium nitrate, and aluminum nitrate as 2:4:0.6:3, a mixed salt solution with a total metal concentration of 0.5mol/L is prepared, which is recorded as solution A; according to c(Na ₂ CO ₃ )=1.0mol/L and c(NaOH)=1.5mol/L are made into mixed alkali solution and denoted as B. The volume usage of solution A and solution B is 1.1. Add solution A and solution B concurrently into a 1L reactor with a concentration of 5g/L graphite oxide dispersion, and control the pH value to 8. After the solution A is added dropwise, age for 12 hours at a temperature of 70°C, and the product is solid Wash to neutral after liquid separation, and dry at 80°C for 48 hours to obtain a composite of hydrotalcite-like precursor and graphite oxide;

Take the catalyst precursor prepared by the above method and put it into a muffle furnace, roast it at a temperature of 500° C. in a nitrogen atmosphere for 4 hours, add the roasted product into the reactor, and feed hydrogen into the reactor with a volume fraction of _H2 of 5%. , argon mixed gas, raised to 400° at a heating rate of 8°C/min for 3h reduction, cooled naturally to room temperature, and introduced synthesis gas with a molar ratio of _H2 and CO of 2:1 to raise the pressure to 3MPa, synthesized The volumetric space velocity of the gas is set to 7800h ^-1 , and the temperature is set to 270°C. The SP3410 gas chromatograph was used for online testing, and the conversion rate of CO and the distribution of each product are shown in Table 2.

[Example 4]

The preparation method of graphite oxide is identical with embodiment 1.

The molar ratio of copper nitrate, cobalt nitrate, manganese nitrate and aluminum nitrate is 1:1:0.1:1 to make a mixed salt solution with a total metal concentration of 2mol/L, which is recorded as solution A; according to c(Na ₂ CO ₃ ) =3mol/L and c(NaOH)=7mol/L are made into mixed alkali solution and denoted as B. The volume of solution A and solution B is 1.5. Add solution A and solution B concurrently into a 1.5mL reactor with a concentration of 4g/L graphite oxide dispersion, and control the pH to be 9. After the dropwise addition of solution A, aging at a temperature of 75°C for 10 hours, washing the product to neutrality after solid-liquid separation, and drying at a temperature of 85°C for 20 hours to obtain a composite of hydrotalcite-like precursor and graphite oxide;

Take the catalyst precursor prepared by the above method and put it into the reactor, feed the mixed gas of hydrogen and argon with _H2 volume fraction of 3% at a volumetric space velocity of 3000 h ^-1 , and raise the temperature to 350 °C at a rate of 1 °C/min °Reduce for 3 hours, cool down to room temperature naturally, and then feed synthesis gas with a molar ratio of H ₂ and CO of 2:1, raise the pressure to 3MPa, set the volume space velocity of the synthesis gas to 3900h ^-1 , and set the temperature to 260°C. The SP3410 gas chromatograph was used for online testing, and the conversion rate of CO and the distribution changes of each product are shown in Table 2.

[Example 5]

The preparation method of graphite oxide is identical with embodiment 1.

According to the molar ratio of copper nitrate, cobalt nitrate, nickel nitrate, and aluminum nitrate as 1:2:0.1:1, a mixed salt solution with a total metal concentration of 0.3mol/L is prepared, which is recorded as solution A; according to c(Na ₂ CO ₃ )=0.3mol/L and c(NaOH)=1mol/L are made into mixed alkali solution and denoted as B. The volume consumption of solution A and solution B is 0.8. Add solution A and solution B concurrently into the reactor of 8g/L graphite oxide dispersion liquid with a concentration of 0.5L, in the reactor containing the above-mentioned graphite oxide sol, and control the pH value to 9.0, after the A solution is added dropwise, in Aging at 70°C for 20 hours, washing the product to neutrality after solid-liquid separation, and drying at 75°C for 20 hours to obtain a composite of hydrotalcite-like precursor and graphite oxide.

Take the catalyst precursor prepared by the above method and put it into a muffle furnace, roast it at a temperature of 500°C in a nitrogen atmosphere for 5 hours, put the ^roasted product into the reactor, and inject _H2 with a volume fraction of 3% hydrogen and argon mixed gas, the temperature rises to 450° at a rate of 5°C/min for 3h reduction, and after natural cooling to room temperature, a synthesis gas with a molar ratio of _H2 and CO of 2:1 is introduced to increase the pressure is 2MPa, the volumetric space velocity of the synthesis gas is set at 4800h ^-1 , and the temperature is set at 260°C. The SP3410 gas chromatograph was used for online testing, and the conversion rate of CO and the distribution changes of each product are shown in Table 2.

[Example 6]

The preparation method of graphite oxide is identical with embodiment 1.

According to the molar ratio of copper nitrate, cobalt nitrate, calcium nitrate, chromium nitrate and aluminum nitrate as 1:1:0.1:0.1:1, make a mixed salt solution with a total metal concentration of 0.1mol/L, which is recorded as solution A; (Na ₂ CO ₃ )=0.15 mol/L and c(NaOH)=0.3 mol/L are formulated into a mixed alkali solution and recorded as B. The volume of solution A and solution B is 1. Add solution A and solution B concurrently into a 1L reactor with a concentration of 2g/L graphite oxide dispersion, and control the pH value to 8.5. After the solution A is added dropwise, age for 20h at a temperature of 100°C, and the product is solid After liquid separation, washing to neutrality and drying at 75°C for 20 hours, a composite of hydrotalcite-like precursor and graphite oxide was obtained.

Take the catalyst prepared by the above method and put it into the reactor, feed the mixed gas of hydrogen and argon with a volume fraction of _H2 of 5% at a volume space velocity of 3000h ^-1 , and raise the temperature to 440° at a rate of 10°C/min for reduction 5h, after natural cooling to room temperature, feed synthesis gas with a molar ratio of H ₂ and CO of 2:1 to increase the pressure to 3MPa, set the volume space velocity of the synthesis gas to 3900h ^-1 , and set the temperature to 300°C. The SP3410 gas chromatograph was used for online testing, and the conversion rate of CO and the distribution of each product are shown in Table 2.

[Example 7]

The preparation method of graphite oxide is identical with embodiment 1.

According to the molar ratio of copper nitrate, cobalt nitrate, magnesium nitrate, and aluminum nitrate as 1:1:1:1, a mixed salt solution with a total metal concentration of 0.5mol/L was prepared, which was recorded as solution A; according to c(Na ₂ CO ₃ )=1mol/L and c(NaOH)=1.8mol/L are made into mixed alkali solution and denoted as B. The volume of solution A and solution B is 1. Add solution A and solution B concurrently into a 1.5L reactor with a concentration of 3g/L graphite oxide dispersion, and control the pH value to 10. After the solution A is added dropwise, age at a temperature of 70°C for 12h, and the product Wash to neutral after solid-liquid separation, and dry at 80°C for 48 hours to obtain a composite of hydrotalcite-like precursor and graphite oxide;

Take the catalyst precursor prepared by the above method and put it into a muffle furnace, roast it at a temperature of 500° C. in a nitrogen atmosphere for 4 hours, add the roasted product into the reactor, and feed hydrogen into the reactor with a volume fraction of _H2 of 5%. , argon mixed gas, raised to 400° at a heating rate of 8°C/min for 3h reduction, cooled naturally to room temperature, and introduced synthesis gas with a molar ratio of _H2 and CO of 2:1 to raise the pressure to 3MPa, synthesized The volumetric space velocity of the gas is set to 7800h ^-1 , and the temperature is set to 270°C. The SP3410 gas chromatograph was used for online testing, and the conversion rate of CO and the distribution of each product are shown in Table 2.

Table 2

The embodiments of the present invention have been described in detail above, but the content is only a preferred embodiment of the present invention, and is not intended to limit the present invention. All modifications, equivalent replacements and improvements made within the application scope of the present invention shall be included in the protection scope of the present invention.

Claims (8)

1. A catalyst for producing low-carbon alcohols from synthesis gas, characterized in that it is made of metal components and graphite components, wherein the graphite components are flake graphite or graphene, and the metal components contain Cu, Co, Al ₂ O ₃ , while each of the above components satisfies the following relationship: The mass fraction of graphite component in the total mass of metal component and graphite component is 0.3~30%; The mass fraction of Cu in the metal composition is 2~25%; The mass fraction of Co in the metal composition is 3~45%; The balance of the metal component is Al ₂ O ₃ ; The flaky graphite is obtained by reduction of flaky graphite oxide with a thickness not exceeding 1000 nm. 2. a kind of catalyst that is used for synthesis gas system low carbon alcohol according to claim 1 is characterized in that described metal component also comprises auxiliary agent, and described auxiliary agent is to contain Zn, Mn, Mg, Ca, Ni, One or more components of Fe and Cr, the mass fraction of the additive in the metal component is not higher than 70%. 3. A catalyst for producing low-carbon alcohols from syngas according to claim 1, characterized in that the graphite component is obtained by reduction of flake graphite oxide with a thickness no more than 100 nm. 4. A kind of catalyst that is used for syngas system low-carbon alcohol according to claim 1, is characterized in that described graphite component is obtained by reduction of graphene oxide. 5. a catalyst preparation method for synthesis gas system low-carbon alcohol as claimed in claim 2, is characterized in that comprising the following steps: 1) Mix 98% (w/w) H ₂ SO ₄ , graphite powder, sodium nitrate and potassium permanganate evenly in an ice bath and stirring condition, and then keep it at -5~5℃ for 1~3 hours, then raise its temperature to 30~40°C and keep stirring for 10~180min, then add the first deionized water to it for dilution, keep the temperature of the mixture below 100°C for 1~5h during this process, and then add 30% (w/w) hydrogen peroxide stirred and reacted for 1~120min, and then added second deionized water to it to prepare a mixed solution with a graphite concentration of 0.5~20g/L, which is a graphite oxide solution. The above 98% (w/ w) The mass ratio of H ₂ SO ₄ , graphite powder, sodium nitrate, potassium permanganate, first deionized water, and 30% (w/w) hydrogen peroxide is (90~95):(1~2.2): (0.9~1.4):(6~7.5):(130~170):(25~35); 2) Add the above ingredients into deionized water to prepare A mixed solution with a total ion concentration of 0.01-2mol/L is recorded as the first mixed solution; Na ₂ CO ₃ and NaOH are prepared into a second mixed solution, and the molar concentration of NaOH in the second mixed solution is guaranteed to be the same as that of the first mixed solution. The ratio of the sum of the molar concentrations of all cations in the solution is (1~5):1, while ensuring that the ratio of the molar concentrations of Na _CO in the second mixed solution to the sum _of the molar concentrations of all divalent cations in the first mixed solution is (1~5): 1; add the first mixed solution and the second mixed solution to the graphite oxide solution obtained in step 1) in parallel, and control the pH value to 8~11. After the first mixed solution is added dropwise Stop the dropwise addition, treat the mixture at a temperature of 60~130°C for 6~48h, then collect the solid phase and wash until neutral, and then fully dry to obtain the complex; 3) The compound obtained in step 2) is reduced for 0.5-6 hours in the presence of a reducing gas with a space velocity of 300-8000 h ^-1 and at a temperature of 200-600 ° C for 0.5-6 h, thereby obtaining the compound used for synthesis gas production. A catalyst for low-carbon alcohols, wherein the reducing gas is a gas containing one or more of hydrogen, carbon monoxide, and methane. 6. The catalyst preparation method for producing low-carbon alcohols from syngas according to claim 5, characterized in that step 3) further includes the following steps before treating the compound with a reducing gas: roasting the compound under the protection of an inert gas . 7. The catalyst preparation method for producing low-carbon alcohols from syngas according to claim 6, characterized in that the specific method of roasting the complex under the protection of an inert gas is as follows: the roasting temperature is 300-800 ° C, the roasting time 0.5~10h, the inert gas composition contains one or more of nitrogen, argon, and helium. 8. A catalyst as claimed in any one of claims 1 to 4 is used to catalyze synthesis gas to prepare the application of low-carbon alcohol, it is characterized in that comprising the following steps: Under the contact condition, the mixed gas of hydrogen and carbon monoxide with a molar ratio of (0.5~3):1 is passed into the reactor at a space velocity of 500~8000h ^-1 under the conditions of 200~350°C and 1~6MPa.