CN118059905A - Method for preparing methanol by integrating carbon dioxide trapping and hydrogenation by using Cu-based catalyst - Google Patents

Abstract

The invention discloses a method for integrating carbon dioxide capture and hydrogenation to methanol using a Cu-based catalyst; a copper-based catalyst is protected by doping elements such as C and P, and its preparation method uses a copper source and an aluminum source as raw materials, ammonia water as a precipitant, a soluble sugar as a carbon source, and phosphoric acid as a phosphorus source, and adopts impregnation-calcination-reduction to obtain a loaded copper-based catalyst doped with elements such as C and P, and the catalyst component includes components such as Cu, Al ₂ O ₃ , C or P. The copper-based catalyst in the invention realizes carbon dioxide capture and hydrogenation to methanol in the liquid phase, and solves the problem of low yield of hydrogenation of carbon dioxide to methanol in the liquid phase.

Description

A method for integrating carbon dioxide capture and hydrogenation to methanol using Cu-based catalysts

Technical Field

The present invention belongs to the technical field of chemical engineering, and relates to a catalytic conversion technology integrating carbon dioxide capture and hydrogenation to produce methanol, and belongs to the technical field of carbon dioxide resource utilization.

Background technique

In recent decades, CO ₂ has attracted research interest due to its greenhouse _{effect on global climate change. Since the 1950s, global atmospheric CO 2 levels} have risen rapidly and have now doubled (212 ppm in 1958 and 445 ppm in 2021). According to relevant model calculations, CO ₂ levels are expected to double again by 2100. As the highest oxidation state of the carbon element, CO ₂ has a formation enthalpy of 396 kJ/mol and has significant thermodynamic stability. Therefore, converting CO ₂ into thermodynamically more stable chemicals, such as Na ₂ CO ₃ , NaHCO ₃ , NH ₄ HCO ₃ and salicylic acid, provides a feasible way for production companies to deal with large amounts of CO ₂ emissions.

Methanol is not only an efficient energy carrier, but also a bulk chemical and an alternative fuel. Nobel Prize winner George A. Olah proposed in the early years that the resource utilization of carbon dioxide to synthesize methanol is in line with the concept of "methanol economy". Methanol is widely used as a basic chemical raw material, and its downstream chemical products are as many as hundreds of kinds, among which formaldehyde, acetic acid and dimethyl ether are its main derivatives. In recent years, with the reduction of oil reserves, the application of methanol has gradually expanded to the field of olefin synthesis. The preparation of catalysts with excellent performance is one of the important factors for realizing the industrialization of _CO2 hydrogenation to methanol. In the past 20 years, the development of catalysts for _CO2 hydrogenation to methanol has become a research hotspot in the field of carbon-one chemistry, and the research focuses on the selection of catalyst composition, improvement and innovation of preparation methods, optimization of reaction conditions and reaction mechanism (Chem. Rev. 2017, 117, 9804–9838). In 1960, ICI first used Cu/ZnO/ _Al2O3 catalyst to synthesize _methanol from synthesis gas under relatively mild reaction conditions (220-300℃, 5-10MPa). Cu/ZnO/Al ₂ O ₃ catalyst has become a commercial catalyst for synthesizing methanol from syngas. At present, copper-based catalysts are still the most widely used catalysts for hydrogenation of carbon dioxide to methanol in industry (ChemSusChem2020,13,6141–6159). Due to the abundance of copper resources on the earth, copper-based catalysts are economical and sustainable in catalysis.

The integration of _CO2 capture and conversion can reduce the cost of _CO2 utilization because it can reduce the cost of energy-consuming desorption and compression steps (ACS Sustain. Chem. Eng. 2019, 7, 12270–12280). Therefore, methanol can be directly obtained by directly using a catalyst to catalyze the hydrogenation of captured _CO2 in an amine solution. After _CO2 is captured, the presence of amines can change the chemical bonds of _CO2 , and the activated _CO2 can be more efficiently hydrogenated, which reduces the reaction temperature for producing methanol (J. Catal. 2020, 389, 247–258). Directly converting _CO2 active species in amine solutions into value-added chemicals can eliminate the _CO2 separation process, simplify the _CO2 utilization process, reduce the reaction temperature, and achieve high efficiency and energy saving (Nat. Rev. Chem. 2021, 5, 564–579; ACS Catal. 2021, 11, 12682–12691; Chem Sus Chem 2021, 14, 4812–4819).

However, in traditional copper-based catalysts, such as Cu/ZnO/Al ₂ O ₃ , the formation of byproduct water during the reaction will lead to competitive adsorption of water on the catalyst, resulting in catalyst deactivation (Catal. Sci. Technol. 2018, 8, 5098–5103). By adjusting the surface properties of the catalyst, for example, by doping with inert elements such as C, the hydrophilicity of the catalyst can be reduced, thereby reducing the adsorption of water on the catalyst. By doping with elements such as P to adsorb byproduct water and reduce the adsorption of water on Al ₂ O ₃ , the competitive adsorption of water can also be reduced, thereby maintaining the activity of the catalyst. We adjust the structure of the copper-based catalyst by doping Cu/Al ₂ O ₃ with elements such as C and P, thereby improving its catalytic performance.

Summary of the invention

The main purpose of the present invention is to integrate carbon dioxide capture and hydrogenation to produce methanol in the liquid phase using a Cu-based catalyst, and to adjust the structure of the copper-based catalyst by doping elements such as C and P, in order to solve the technical problem that traditional copper-based catalysts are deactivated during the reaction, resulting in low methanol yield.

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

1. A method for integrating carbon dioxide capture and hydrogenation to produce methanol using a Cu-based catalyst, characterized in that it comprises the following steps:

1) Mix a metal copper salt and a metal aluminum salt and dissolve them in deionized water, stirring and dissolving them, and the solution is recorded as solution a; add ammonia water to deionized water to obtain diluted ammonia water, dissolve a soluble sugar (one of sucrose, glucose, and fructose) as a carbon source in the diluted ammonia water, and the obtained solution is recorded as solution b; add solution a dropwise into solution b, age in a beaker for 2 hours, place in an oil bath, stir and dry at 50-70° C., and then transfer to a 90-100° C. oven for drying for 12 hours to obtain a dried material; transfer the dried material to a muffle furnace, calcine at 300-600° C. for 3-14 hours, grind it, and then reduce it in a tubular furnace, and reduce it at 300-600° C. for 1-12 hours under hydrogen to obtain three carbon-doped copper-based catalysts, namely Cu/Al ₂ O ₃ -sucrose, Cu/Al ₂ O ₃ -glucose, and Cu/Al ₂ O ₃ -fructose, where sucrose, glucose, and fructose represent sucrose, glucose, and fructose, respectively;

2) adding anhydrous ethanol into a reaction kettle; adding a catalyst mixture equivalent to 0.1-10 wt% of anhydrous ethanol into the reaction kettle, wherein the catalyst may be one or more of Cu/Al ₂ O ₃ -sucrose, Cu/Al ₂ O ₃ -glucose and Cu/Al ₂ O ₃ -fructose; then charging with 0.1-1 MPa carbon dioxide and 2-20 MPa hydrogen; then reacting the reaction kettle at 150-250° C. and 600-1000 rpm for 2-24 hours; after cooling, a reaction liquid containing methanol is obtained, and the yield of methanol is analyzed by gas chromatography.

2. A method for integrating carbon dioxide capture and hydrogenation to produce methanol using a Cu-based catalyst, characterized in that it comprises the following steps:

1) Mix a metal copper salt and a metal aluminum salt and dissolve them in deionized water, stirring and dissolving them, and the solution is recorded as solution a; add ammonia water to deionized water to obtain diluted ammonia water, dissolve a soluble sugar (one of sucrose, glucose, and fructose) as a carbon source in the diluted ammonia water, and the obtained solution is recorded as solution b; add solution a dropwise into solution b, age in a beaker for 2 hours, place in an oil bath, stir and dry at 50-70° C., and then transfer to a 90-100° C. oven for drying for 12 hours to obtain a dried material; transfer the dried material to a muffle furnace, calcine at 300-600° C. for 3-14 hours, grind it, and then reduce it in a tubular furnace, and reduce it at 300-600° C. for 1-12 hours under hydrogen to obtain three carbon-doped copper-based catalysts, namely Cu/Al ₂ O ₃ -sucrose, Cu/Al ₂ O ₃ -glucose, and Cu/Al ₂ O ₃ -fructose, where sucrose, glucose, and fructose represent sucrose, glucose, and fructose, respectively;

2) adding triethylamine equivalent to 0.5-20% of anhydrous ethanol to anhydrous ethanol to obtain an ethanol solution of amine; placing the ethanol solution of amine in a reaction kettle, adding a catalyst equivalent to 0.1-10wt% of the ethanol solution of amine to the ethanol solution of amine in the reaction kettle, wherein the catalyst may be one or more of Cu/ _{Al2O3 -} sucrose, Cu/ _{Al2O3 -glucose} , and Cu/ _Al2O3 - _fructose ; then charging with 0.1-1MPa of carbon dioxide and 2-20MPa of hydrogen; then reacting the reaction kettle at 150-250°C and a rotation speed of 600-1000rpm for 2-24 hours; after cooling, a reaction solution containing methanol can be obtained, and the yield of methanol is analyzed by gas chromatography.

3. A method for integrating carbon dioxide capture and hydrogenation to produce methanol using a Cu-based catalyst, characterized in that it comprises the following steps:

1) Mix a metal copper salt and a metal aluminum salt and dissolve them in deionized water by stirring, and the solution is recorded as solution a; add ammonia water to deionized water to obtain diluted ammonia water, and dissolve phosphoric acid as a phosphorus source in the diluted ammonia water, and the obtained solution is recorded as solution b; add solution a dropwise into solution b, age in a beaker for 2 hours, place in an oil bath, stir and dry at 50-70° C., and then transfer to a 90-100° C. oven for drying for 12 hours to obtain a dried material; transfer the dried material to a muffle furnace, calcine at 300-600° C. for 3-14 hours, grind, and then reduce in a tubular furnace, and reduce at 300-600° C. for 1-12 hours under hydrogen to obtain Cu/Al ₂ O ₃ -phosphoric, a copper-based catalyst doped with phosphorus, where phosphoric represents phosphoric acid;

2) Adding anhydrous ethanol into a reaction kettle; then adding a catalyst mixture equivalent to 0.1-10 wt% of anhydrous ethanol into the reaction kettle, wherein the catalyst is Cu/Al ₂ O ₃ -phosphoric; then charging 0.1-1 MPa of carbon dioxide and 2-20 MPa of hydrogen; then the reaction kettle is reacted at 150-250° C. and 600-1000 rpm for 2-24 hours; after cooling, a reaction liquid containing methanol is obtained, and the yield of methanol is analyzed by gas chromatography.

4. A method for integrating carbon dioxide capture and hydrogenation to produce methanol using a Cu-based catalyst, characterized in that it comprises the following steps:

1) Mix a metal copper salt and a metal aluminum salt and dissolve them in deionized water by stirring, and the solution is recorded as solution a; add ammonia water to deionized water to obtain diluted ammonia water, and dissolve phosphoric acid as a phosphorus source in the diluted ammonia water, and the obtained solution is recorded as solution b; add solution a dropwise into solution b, age in a beaker for 2 hours, place in an oil bath, stir and dry at 50-70° C., and then transfer to a 90-100° C. oven for drying for 12 hours to obtain a dried material; transfer the dried material to a muffle furnace, calcine at 300-600° C. for 3-14 hours, grind, and then reduce in a tubular furnace, and reduce at 300-600° C. for 1-12 hours under hydrogen to obtain Cu/Al ₂ O ₃ -phosphoric, a copper-based catalyst doped with phosphorus, where phosphoric represents phosphoric acid;

2) adding triethylamine equivalent to 0.5-20% of anhydrous ethanol to anhydrous ethanol to obtain an ethanol solution of amine; placing the ethanol solution of amine in a reaction kettle, adding a catalyst equivalent to 0.1-10wt% of the ethanol solution of amine to the ethanol solution of amine in the reaction kettle, wherein the catalyst is Cu/Al ₂ O ₃ -phosphoric; then charging 0.1-1MPa of carbon dioxide and 2-20MPa of hydrogen; then reacting the reaction kettle at 150-250°C and a rotation speed of 600-1000rpm for 2-24 hours; after cooling, a reaction solution containing methanol can be obtained, and the yield of methanol is analyzed by gas chromatography.

The present invention adopts the above technical solution, which has the following advantages:

In view of the high energy consumption of industrial production of methanol by hydrogenation of carbon dioxide in the gas phase, we proposed to use Cu-based catalysts to integrate carbon dioxide capture and hydrogenation to produce methanol in the liquid phase. We have developed a new catalyst preparation method, which reduces the competitive adsorption of water formed during the hydrogenation of carbon dioxide by doping C and P on the supported copper-based catalyst, so that the doped copper-based catalyst has better activity and the yield of methanol is also improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1: Methanol yields obtained by catalytic conversion of carbon dioxide in pure ethanol solvent over different catalysts.

Figure 2: Methanol yields obtained by catalytic conversion of carbon dioxide in ethanol solvent with the addition of triethylamine over different catalysts.

Detailed ways

The present invention is described in detail below by way of examples.

Example 1

There are four steps to prepare the 20wt% Cu/ _{Al2O3 catalyst} :

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, 4.2 mL of ammonia water was taken, and then deionized water was added to 20 mL, and the mixture was stirred and dissolved at 500 rpm to obtain an ammonia solution. The solution in the first step was then added dropwise to the ammonia solution and aged for 2 h.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400°C for 3 hours, and then reduced in a tubular furnace at 400°C for 2 hours in a hydrogen atmosphere to obtain a 20wt% Cu _{/ Al2O3} catalyst.

Reaction part:

First, 20 mL of ethanol was added into the reactor, and then 0.3 g of 20 wt% Cu/Al ₂ O ₃ catalyst was placed into the reactor, 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged, and the reaction was carried out at 200° C. for 6 hours to obtain a reaction solution containing methanol.

Example 2

There are four steps to prepare 20wt% Cu/Al ₂ O ₃ -sucrose catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 2 g of fructose (sucrose), stir and dissolve at 500 rpm to obtain an aqueous solution of sucrose, then add the solution of the first step dropwise into the aqueous solution of sucrose, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -sucrose catalyst.

Reaction part:

First, 20 mL of ethanol was added to the reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -sucrose catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and then a reaction liquid containing methanol was obtained.

Example 3

There are four steps to prepare 20wt% Cu/Al ₂ O ₃ -glucose catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 2 g of glucose, stir and dissolve at 500 rpm to obtain an aqueous solution of glucosamine, then add the solution of the first step dropwise to the aqueous solution of glucosamine, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -glucose catalyst.

Reaction part:

First, 20 mL of ethanol was added to the reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -glucose catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and then a reaction liquid containing methanol was obtained.

Example 4

There are four steps to prepare 20wt% Cu/ _{Al2O3 -} fructose catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 2 g of fructose, stir and dissolve at 500 rpm to obtain an aqueous solution of glucosamine, then add the solution of the first step dropwise to the aqueous solution of glucosamine, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -fructose catalyst.

Reaction part:

First, 20 mL of ethanol was added to the reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -fructose catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and then a reaction liquid containing methanol was obtained.

Example 5

There are four steps to prepare 20wt% Cu/ _Al2O3 - _phosphoric catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 0.0309 g of phosphoric acid, stir and dissolve at 500 rpm to obtain an ammonia phosphoric acid aqueous solution, then add the solution of the first step dropwise to the ammonia phosphoric acid aqueous solution, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -phosphoric catalyst.

Reaction part:

First, 20 mL of ethanol was added to the reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -phosphoric catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and then a reaction liquid containing methanol was obtained.

The yield of methanol is expressed as the molar amount of methanol divided by the molar amount of carbon dioxide as a reaction raw material. The yields of methanol obtained in Examples 1-5 are shown in FIG1 .

Example 6

There are four steps to prepare the 20wt% Cu/ _{Al2O3 catalyst} :

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, 4.2 mL of ammonia water was taken, and then deionized water was added to 20 mL, and the mixture was stirred and dissolved at 500 rpm to obtain an ammonia solution. The solution of the first step was then added dropwise to the ammonia solution and aged for 2 h.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400°C for 3 hours, and then reduced in a tubular furnace at 400°C for 2 hours in a hydrogen atmosphere to obtain a 20wt% Cu _{/ Al2O3} catalyst.

Reaction part:

First, 19 mL of ethanol and 1 mL of triethylamine were mixed and added to a reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and a reaction liquid containing methanol was obtained.

Example 7

There are four steps to prepare 20wt% Cu/Al ₂ O ₃ -sucrose catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 2 g of fructose (sucrose), stir and dissolve at 500 rpm to obtain an aqueous solution of sucrose, then add the solution of the first step dropwise into the aqueous solution of sucrose, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -sucrose catalyst.

Reaction part:

First, 19 mL of ethanol and 1 mL of triethylamine were mixed and added to a reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -sucrose catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and a reaction solution containing methanol was obtained.

Example 8

There are four steps to prepare 20wt% Cu/Al ₂ O ₃ -glucose catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 2 g of glucose, stir and dissolve at 500 rpm to obtain an aqueous solution of glucosamine, then add the solution of the first step dropwise to the aqueous solution of glucosamine, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -glucose catalyst.

Reaction part:

First, 19 mL of ethanol and 1 mL of triethylamine were mixed and added to a reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -glucose catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and a reaction solution containing methanol was obtained.

Example 9

There are four steps to prepare 20wt% Cu/ _{Al2O3 -} fructose catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 2 g of fructose, stir and dissolve at 500 rpm to obtain an aqueous solution of glucosamine, then add the solution of the first step dropwise to the aqueous solution of glucosamine, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -fructose catalyst.

Reaction part:

First, 19 mL of ethanol and 1 mL of triethylamine were mixed and added to a reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -fructose catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and a reaction solution containing methanol was obtained.

Example 10

There are four steps to prepare 20wt% Cu/ _Al2O3 - _phosphoric catalyst:

In the first step, 2.94 g of Al(NO ₃ ) ₃ ·9H ₂ O and 0.38 g of Cu(NO ₃ ) ₂ ·3H ₂ O were mixed and dissolved in 20 mL of deionized water, and the mixture was stirred at 500 rpm to dissolve.

In the second step, take 4.2 mL of ammonia water, then add deionized water to 20 mL, then add 0.0309 g of phosphoric acid, stir and dissolve at 500 rpm to obtain an ammonia phosphoric acid aqueous solution, then add the solution of the first step dropwise to the ammonia phosphoric acid aqueous solution, and then age for 2 hours.

In the third step, the solution from the second step was placed in an oil bath and stirred at 50-70°C until dry, and then transferred to a 90°C oven for drying for 12 hours.

In the fourth step, the sample obtained in the third step was placed in a muffle furnace and calcined at 400° C. for 3 h, and then reduced in a tubular furnace at 400° C. for 2 h in a hydrogen atmosphere to obtain a 20 wt% Cu/Al ₂ O ₃ -phosphoric catalyst.

Reaction part:

First, 1 mL of triethylamine and 19 mL of ethanol were mixed and added to a reactor, and 0.3 g of 20 wt% Cu/Al ₂ O ₃ -phosphoric catalyst was added to the reactor, and 0.5 MPa CO ₂ and 3.5 MPa H ₂ were charged. The reaction was carried out at 200° C. for 6 hours, and a reaction solution containing methanol was obtained.

The yield of methanol is expressed as the molar amount of methanol divided by the molar amount of carbon dioxide as a reaction raw material. The yields of methanol obtained in Examples 6-10 are shown in FIG. 2 .

Claims (10)

1. A method for preparing methanol by integrating carbon dioxide capturing and hydrogenation by utilizing a Cu-based catalyst, which is characterized by comprising the following steps:

1) Mixing and dissolving copper salt and aluminum salt in deionized water, and stirring to dissolve, wherein the solution is denoted as a solution a; adding ammonia water into deionized water to obtain diluted ammonia water, and dissolving soluble sugar serving as a carbon source into the diluted ammonia water to obtain a solution b; dropwise adding the solution a into the solution b, ageing for 1-12 h, stirring and drying at 30-90 ℃, and then transferring to a condition of 90-120 ℃ for drying for 1-12 h to obtain a dried material; transferring the dried material into a muffle furnace, calcining at 300-600 ℃ for 3-14 h, grinding, reducing by using a tube furnace, and reducing at 300-600 ℃ for 1-12 h under hydrogen to obtain the carbon-doped copper-based catalyst;

2) Adding absolute alcohol into a reaction kettle; adding 0.1-10wt% of carbon-doped copper-based catalyst equivalent to absolute alcohol into a reaction kettle, and mixing; filling 0.1-1 MPa carbon dioxide and 2-20 MPa hydrogen into the reaction kettle; the reaction kettle reacts for 2 to 24 hours at the temperature of 150 to 250 ℃ and the rotating speed of 600 to 1000 rpm; and cooling to obtain a reaction solution containing methanol.

2. A method for preparing methanol by integrating carbon dioxide capturing and hydrogenation by utilizing a Cu-based catalyst, which is characterized by comprising the following steps:

1) Mixing and dissolving copper salt and aluminum salt in deionized water, and stirring to dissolve, wherein the solution is denoted as a solution a; adding ammonia water into deionized water to obtain diluted ammonia water, and dissolving soluble sugar serving as a carbon source into the diluted ammonia water to obtain a solution b; dropwise adding the solution a into the solution b, ageing for 1-12 h, stirring and drying at 30-90 ℃, and then transferring to a condition of 90-120 ℃ for drying for 1-12 h to obtain a dried material; transferring the dried material into a muffle furnace, calcining at 300-600 ℃ for 3-14 h, grinding, reducing by using a tube furnace, and reducing at 300-600 ℃ for 1-12 h under hydrogen to obtain the carbon-doped copper-based catalyst;

2) Adding 0.5-20wt% of amine equivalent to absolute alcohol into absolute alcohol to obtain an alcohol solution of the amine; placing an amine alcohol solution in a reaction kettle, and adding a carbon-doped copper-based catalyst accounting for 0.1-10wt% of the amine alcohol solution into the alcohol solution in the reaction kettle for mixing; filling 0.1-1 MPa carbon dioxide and 2-20 MPa hydrogen into the reaction kettle; the reaction kettle reacts for 2 to 24 hours at the temperature of 150 to 250 ℃ and the rotating speed of 600 to 1000 rpm; and cooling to obtain a reaction solution containing methanol.

3. A method for preparing methanol by integrating carbon dioxide capturing and hydrogenation by utilizing a Cu-based catalyst, which is characterized by comprising the following steps:

1) Mixing and dissolving copper salt and aluminum salt in deionized water, and stirring to dissolve, wherein the solution is denoted as a solution a; adding ammonia water into deionized water to obtain diluted ammonia water, and dissolving phosphoric acid serving as a phosphorus source into the diluted ammonia water to obtain a solution b; dropwise adding the solution a into the solution b, ageing for 1-12 h, stirring and drying at 30-90 ℃, and then transferring to a condition of 90-120 ℃ for drying for 1-12 h to obtain a dried material; transferring the dried material into a muffle furnace, calcining at 300-600 ℃ for 3-14 h, grinding, reducing by using a tubular furnace, and reducing at 300-600 ℃ for 1-12 h under hydrogen to obtain a phosphorus-doped copper-based catalyst, namely Cu/Al ₂O₃ -phosphorus, wherein phosphorus represents phosphoric acid;

2) Adding absolute alcohol into a reaction kettle; adding a catalyst which is equivalent to 0.1-10wt% of absolute alcohol into the reaction kettle, and mixing, wherein the catalyst is Cu/Al ₂O₃ -phosphorus; filling 0.1-1 MPa carbon dioxide and 2-20 MPa hydrogen into the reaction kettle; the reaction kettle reacts for 2 to 24 hours at the temperature of 150 to 250 ℃ and the rotating speed of 600 to 1000 rpm; and cooling to obtain a reaction solution containing methanol.

4. A method for preparing methanol by integrating carbon dioxide capturing and hydrogenation by utilizing a Cu-based catalyst, which is characterized by comprising the following steps:

1) Mixing and dissolving copper salt and aluminum salt in deionized water, and stirring to dissolve, wherein the solution is denoted as a solution a; adding ammonia water into deionized water to obtain diluted ammonia water, and dissolving phosphoric acid serving as a phosphorus source into the diluted ammonia water to obtain a solution b; dropwise adding the solution a into the solution b, ageing for 1-12 h, stirring and drying at 30-90 ℃, and then transferring to a condition of 90-120 ℃ for drying for 1-12 h to obtain a dried material; transferring the dried material into a muffle furnace, calcining at 300-600 ℃ for 3-14 h, grinding, reducing by using a tubular furnace, and reducing at 300-600 ℃ for 1-12 h under hydrogen to obtain a phosphorus-doped copper-based catalyst, namely Cu/Al ₂O₃ -phosphorus, wherein phosphorus represents phosphoric acid;

2) Adding 0.5-20% of amine equivalent to absolute alcohol into absolute alcohol to obtain an alcohol solution of the amine; placing an amine alcohol solution in a reaction kettle, and adding a catalyst which is equivalent to 0.1-10wt% of the amine alcohol solution into the amine alcohol solution in the reaction kettle, wherein the catalyst is Cu/Al ₂O₃ -phosphorus; filling 0.1-1 MPa carbon dioxide and 2-20 MPa hydrogen into the reaction kettle; the reaction kettle reacts for 2 to 24 hours at the temperature of 150 to 250 ℃ and the rotating speed of 600 to 1000 rpm; and cooling to obtain a reaction solution containing methanol.

5. The method according to any of claims 1-4, wherein the copper metal salt is one or more of copper nitrate, copper acetate, copper sulfate, copper phosphate, copper carbonate, copper aluminate, copper chloride; the metal aluminum salt can be one or more of aluminum nitrate, aluminum acetate, aluminum sulfate, aluminum phosphate and aluminum chloride; the mass ratio of the metal copper salt to the water in the solution a is 1:100 ～ 100 ～ 1; the mass ratio of the metal aluminum salt to the water in the solution a is 1: 100-100: 1, a step of; the concentration of the ammonia water in the obtained diluted ammonia water is 1-20wt%.

6. The method according to claim 1 or 2, characterized in that the mass ratio of soluble sugars to diluted ammonia is 1: 100-100: 1, a step of; the soluble saccharide can be one or more of sucrose, glucose, fructose, mannose, lactose, galactose, ribose, xylose, arabinose, mannose, maltose, and deoxyribose.

7. The method according to claim 3 or 4, wherein the mass ratio of phosphoric acid to diluted ammonia is 1: 100-100: 1.

8. A process according to claim 1 or 2, characterized in that the carbon doped copper based catalyst may be one or more ,sucrose、glucose、fructose、mannose,lactose,galactose,ribose,xylose,arabinose,mannose,maltose and deoxyribose of Cu/Al₂O₃-sucrose、Cu/Al₂O₃-glucose、Cu/Al₂O₃-fructose、Cu/Al₂O₃-mannose、Cu/Al₂O₃-lactose、Cu/Al₂O₃-galactose、Cu/Al₂O₃-ribose、Cu/Al₂O₃-xylose、Cu/Al₂O₃-arabinose、Cu/Al₂O₃-mannose、Cu/Al₂O₃-maltose、Cu/Al₂O₃-deoxyribose representing sucrose, glucose, fructose, mannose, lactose, galactose, ribose, xylose, arabinose, mannose, maltose and deoxyribose, respectively; adding one or more of Cu/Al₂O₃-sucrose、Cu/Al₂O₃-glucose、Cu/Al₂O₃-fructose、Cu/Al₂O₃-mannose、Cu/Al₂O₃-lactose、Cu/Al₂O₃-galactose、Cu/Al₂O₃-ribose、Cu/Al₂O₃-xylose、Cu/Al₂O₃-arabinose、Cu/Al₂O₃-mannose、Cu/Al₂O₃-maltose、Cu/Al₂O₃-deoxyribose carbon-doped copper-based catalysts which are 0.1-10wt% of absolute alcohol to a reaction kettle in the method of claim 1; the method of claim 2 wherein the carbon-doped copper-based catalyst is one or more of Cu/Al₂O₃-sucrose、Cu/Al₂O₃-glucose、Cu/Al₂O₃-fructose、Cu/Al₂O₃-mannose、Cu/Al₂O₃-lactose、Cu/Al₂O₃-galactose、Cu/Al₂O₃-ribose、Cu/Al₂O₃-xylose、Cu/Al₂O₃-arabinose、Cu/Al₂O₃-mannose、Cu/Al₂O₃-maltose、Cu/Al₂O₃-deoxyribose added to the alcoholic solution of amine in the reaction vessel in an amount of 0.1 to 10wt% based on the alcoholic solution of amine.

9. A method according to any one of claims 1 or 3, wherein the volume of the added absolute alcohol is 10-80% of the volume of the reaction kettle; the anhydrous alcohol can be methanol, ethanol, propanol, butanol, amyl alcohol, hexanol, ethylene glycol, 1, 3-propylene glycol, 1, 2-propylene glycol; one or more of 1, 4-butanediol, 1, 3-butanediol, 2, 3-butanediol, 1, 5-pentanediol, and glycerol.

10. The method according to any one of claims 2 or 4, wherein the volume of the alcohol solution of the amine added is 10-80% of the volume of the reaction kettle; the anhydrous alcohol can be methanol, ethanol, propanol, butanol, amyl alcohol, hexanol, ethylene glycol, 1, 3-propylene glycol, 1, 2-propylene glycol; one or more of 1, 4-butanediol, 1, 3-butanediol, 2, 3-butanediol, 1, 5-pentanediol, glycerol; the amine is one or more of trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, tripropanolamine, tributylamine, N-methylpiperidine, N-ethylpiperidine, N-propylpiperidine, N-methanolpiperidine, N-ethanolpiperidine, N-propanolpiperidine, N-methylpyrrolidine, N-ethylpyrrolidine, N-propylpyrrolidine, N-methanolpyrrolidine, N-ethanolpyrrolidine, and N-propanolpyrrolidine.