A method and catalyst for preparing ethyl formate by carbonylation of ethanol and carbon dioxide

Abstract

The present invention provides a method and catalyst for preparing ethyl formate by carbonylation of ethanol with carbon dioxide. The catalyst is copper-doped strontium titanate (SrTiCuO 3‑x The catalyst, loaded with copper at a copper loading of 0.0-3.50 wt%, exists in the form of nanoparticles with an average particle size of 2-20 nm. Under 300W xenon lamp illumination, with carbon dioxide as the carbonyl source, the HCOOC2H5 generation rate can reach up to 320 μmol / g / h, with good reproducibility.

Description

Technical Field

[0001] The present invention relates to the fields of chemistry, chemical engineering and catalysis, and in particular to a method and a catalyst for preparing ethyl formate by carbonylation reaction of ethanol and carbon dioxide. Background Art

[0002] Ethanol has abundant sources. It can be derived from renewable biomass. my country's annual bioethanol production capacity has exceeded 4 million tons. It can also be derived from coal resources. At present, ethanol is mainly used as a fuel additive. The rapid development of electric vehicles and hydrogen fuel vehicles will inevitably bring a huge impact on the ethanol fuel industry. Therefore, it is of great significance to plan the ethanol downstream industry in advance and convert ethanol into high value-added chemicals to promote the sustainable development of renewable resources. Ethanol molecules have a rich variety of chemical bonds, including C α -H bond, C β Ethyl formate can be produced through the carbonylation of ethanol, using various chemical bonds, including -H, OH, CO, and CC, to produce products such as 2,3-butanediol, ethylene glycol, diethyl carbonate, ethyl formate, ethyl ether, n-butanol, and hydrogen. Ethyl formate, a product of ethanol carbonylation, is an edible flavoring widely used in the formulation of fruity and wine-flavored flavors. Ethyl formate can also be used as an intermediate in pharmaceuticals such as fulvicidin, uracil, cytosine, thymine, and vitamin B1. Ethyl formate is also a good solvent, serving as a solvent for nitrocellulose and cellulose acetate, and as an organic solvent in pharmaceutical production.

[0003] In the carbonylation reaction of ethanol, CO gas is widely used due to its relatively low price and abundant content. However, CO gas is highly toxic and flammable, and is potentially dangerous. In addition, in the gas-phase oxidative carbonylation reaction of ethanol, there is an explosion hazard due to the presence of oxygen in the reaction system. Therefore, there is an urgent need to find a more abundant, easily available, low-cost, environmentally friendly and safe carbonyl source to meet the carbonylation reaction of ethanol. Carbon dioxide has become a popular C1 source due to its non-toxicity, abundance, availability and recyclability. However, the molecular structure of carbon dioxide is symmetrical, the bond energy is high, it is thermodynamically stable and kinetically inert, and it needs to be activated under harsh conditions. Under harsh conditions, ethanol is easily overactivated, resulting in reduced selectivity of the target product.

[0004] The use of carbonyl groups as carbonyl sources has been reported one after another. For example, He et al. first photocatalytically reduced CO2 to CO in two connected autoclave systems, and combined it with the subsequent carbonylation reaction to form CC / CN / CO bonds to provide value-added chemicals (ChemSusChem, 2018, 11: 3382-3387). Fu et al. achieved the coupling of CO2 photoreduction and Suzuki / Sonogashira reaction in a single reaction system (Journal of the American Chemical Society, 2021, 143, 20792-20801).

[0005] However, since carbon dioxide is relatively inert in thermodynamics and kinetics, it requires relatively harsh conditions to activate carbon dioxide. Under harsh conditions, the ethanol molecules themselves will produce a large amount of by-products, which reduces the selectivity of the target product. Therefore, there are currently few reports on the carbonylation of C2H5OH and CO2 to prepare high-value-added products. Summary of the Invention

[0006] The present invention provides a method and catalyst for preparing ethyl formate by carbonylation of ethanol using carbon dioxide as a carbonyl source.

[0007] A method for preparing ethyl formate through the carbonylation reaction of ethanol with carbon dioxide comprises the following steps: placing a catalyst and ethanol in a closed photothermal reactor, introducing reaction gas CO2 at a flow rate of 10-60 mL / min, adjusting the pressure of the photothermal reactor to 0.1-0.4 MPa, then turning on a constant current irradiation xenon lamp light source to initiate a photothermal catalytic reaction, and reacting for 1-10 hours to obtain ethyl formate, wherein the amount of the catalyst used is 2-20% of the mass of the added ethanol.

[0008] Furthermore, in the photothermal reactor, the light source is a constant current irradiation xenon lamp light source, the catalyst is placed in the center of the powder sample platform in the photothermal reactor, the thermocouple probe is placed in the center of the sample platform, ethanol is pipetted and dripped around the powder platform, and then the reactor is closed, and the gas in the reactor is replaced with N2 gas several times, and then the reaction gas CO2 is introduced at a flow rate of 10-60mL / min, and the pressure is adjusted to 0.1-0.4MPa. After that, the light source is turned on to start the photothermal catalytic reaction, and the reaction time is 1-10h to obtain the ethyl formate.

[0009] Furthermore, the catalyst is copper-doped strontium titanate (SrTiCuO 3-x )Load copper.

[0010] Furthermore, the copper is one or two of metallic copper, cuprous oxide and cupric oxide.

[0011] Furthermore, the SrTiCuO 3-x With abundant and tunable oxygen vacancies.

[0012] Furthermore, the copper loading is 0.0-3.50 wt%, based on the SrTiCuO 3-x The average particle size is 2nm-20nm based on the mass.

[0013] Furthermore, the SrTiCuO 3-x The morphology is one of a truncated dodecahedron, a cube, and a truncated tetradecahedron.

[0014] Furthermore, the copper and SrTiCuO 3-x The interfacial sites are abundant and adjustable.

[0015] Furthermore, the carrier SrTiCuO 3-x The XRD characterization diagram of 2θ is 22.78°, 32.42°, 39.98°, 46.48°,

[0016] Characteristic diffraction peaks of strontium titanate structure appear at 52.36°, 57.79°, 67.80 and 77.18°, which are attributed to the (100), (110), (111), (200), (210), (211), (200) and (310) crystal planes in SrTiCuO3, respectively.

[0017] Furthermore, the catalyst is SrTiCuO3 which is reduced by a reducing agent to dissolve copper in situ to obtain SrTiCuO 3-x Loaded Cu, i.e. Cu-SrTiCuO 3-x .

[0018] Furthermore, the reducing agent is one of glucose, sulfite, hydrazine hydrate, sodium ascorbate, hydrogen, and sodium borohydride.

[0019] Furthermore, the SrTiCuO 3-x Preparation of SrTiCuO by loading Cu and etching with Na2S2O3 3-x -E.

[0020] Furthermore, the catalyst is also in the SrTiCuO 3-x -E to obtain SrTiCuO 3-x -E loads Cu,

[0021] Cu / SrTiCuO 3-x -E.

[0022] Furthermore, the SrTiCuO3 is prepared by a hydrothermal method or a sol-gel method.

[0023] Furthermore, the Cu-SrTiCuO 3-x The preparation method comprises the following steps:

[0024] Step 1) preparing the precursor SrTiCuO3 by a hydrothermal method or a sol-gel method;

[0025] Step 2) The precursor SrTiCuO3 is subjected to reduction treatment to dissolve copper.

[0026] Furthermore, in step 1), any one of ethylene glycol, ethanol, 1,2-propylene glycol, 1,4-butanediol, and pentaerythritol is added to the mixture under continuous stirring. 16 H 36 O4Ti, stir and mix evenly, then add water and continue stirring to obtain solution A; mix the alkali solution and water evenly to obtain solution B;

[0027] Dissolve SrCl2·6H2O and copper salt Cu(NO3)2·3H2O in water to obtain solution C;

[0028] Then, the solutions B and C were added dropwise to the solution A under low temperature conditions. After the addition was complete, the mixture was kept warm and stirred for a period of time.

[0029] The mixed solution is transferred into an autoclave, and then the autoclave is transferred into an oven for crystallization. After the crystallization is completed, the mixture is cooled to room temperature, washed, dried and calcined to obtain the SrTiCuO3 composite oxide precursor.

[0030] Furthermore, in step 1), the ethanol, 1,2-propylene glycol, 1,4-butanediol, and pentaerythritol are alcohols of different acidities, which, as surfactants, can control the shape of the composite oxide precursor SrTiCuO3 during the synthesis to regulate the different exposed crystal faces. 16 H 36 O4Ti can be dissolved in alcohol to avoid its rapid hydrolysis.

[0031] Furthermore, in step 1), the alkali metal solution, preferably LiOH·H2O, is used to adjust the pH to alkaline, thereby promoting the dissociation of hydrogen by the corresponding alcohol molecules.

[0032] Furthermore, in step 1), C 16 H 36 The molar ratios of O4Ti, Cu(NO3)2·3H2O, SrCl2·6H2O and LiOH·H2O are (1-0.8):(0-0.20):(0.9-1.1):(2-5).

[0033] Furthermore, in step 1), the concentration of the LiOH·H2O aqueous solution is 1-5 mol / L.

[0034] Furthermore, in step 1), the volume ratio of the water to the ethylene glycol is 1:(0.1-0.5).

[0035] Furthermore, in step 1), the low temperature condition of adding the solutions B and C dropwise into the solution A is 0-15°C.

[0036] Furthermore, in step 1), the solutions B and C are added dropwise to the solution A in sequence, and the mixture is kept warm and stirred for 0-1 h.

[0037] Furthermore, in step 2), the molar ratio of SrTiCuO3, NaOH, and any one of glucose, sulfite, hydrazine hydrate, sodium ascorbic acid, etc. is 1: (0.5-4): (2-256).

[0038] Furthermore, the Cu / SrTiCuO 3-x -E preparation method comprises the following steps:

[0039] Step S1) Cu-SrTiCuO 3-x Add it to a solution containing Na2S2O3, carve away the surface copper, and prepare SrTiCuO 3-x -E;

[0040] Step S2) the SrTiCuO 3-x -E was added to a certain amount of deionized water, and then under magnetic stirring, Cu(NO3)2 aqueous solution was added dropwise, NaOH aqueous solution was added and heated, and glucose solution was further added and kept for a certain time. After the solid product was repeatedly washed, the solid product was dried under vacuum conditions to obtain Cu / SrTiCuO 3-x -E.

[0041] Furthermore, in step S1), the Cu-SrTiCuO 3-x The molar ratio of the Na2SO3 is 1:(0.1-1).

[0042] Furthermore, in step S1), the reaction time at room temperature is 0-1.5h.

[0043] Furthermore, in step S2), the insulation time is 0-0.5h.

[0044] The beneficial effects of the present invention are:

[0045] 1. The catalyst of the present invention realizes the carbonylation of ethanol to produce ethyl formate using carbon dioxide as a carbonyl source, and the production rate of ethyl formate can reach 320 μmol / g / h.

[0046] 2. In the catalyst of the present invention, due to the presence of Cu and SrTiCuO 3-x The rich interface sites between Cu and SrTiCuO promote the coupling of C2H5OH intermediates and CO2 intermediates. In the photocatalytic carbonylation of ethanol and carbon dioxide to prepare ethyl formate, the Cu site activates the C=O bond of CO2 to generate active *CO. 3-x Surface oxygen vacancies activate the OH bonds of C2H5OH to generate C2H5O*, Cu and SrTiCuO 3-x The interfacial sites between them promote the coupling of C2H5O* and *CO to produce ethyl formate. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 These are the XRD patterns of the catalysts of precursor SrTiCuO3 (a), Example 1 (b), Comparative Example 1 (c), and Example 2 (c). DETAILED DESCRIPTION

[0048] Example 1Cu-SrTiCuO 3-x Preparation and photocatalytic carbonylation of ethanol and carbon dioxide

[0049] 1) Preparation of composite oxide precursor SrTiCuO3

[0050] Add a certain amount of ethylene glycol to a three-necked flask, stir vigorously, and add an appropriate amount of C 16 H 36 O4Ti and deionized water are mixed to obtain Solution A. Simultaneously, an appropriate amount of LiOH·H2O is dissolved in deionized water to obtain Solution B, and an appropriate ratio of SrCl2·6H2O and Cu(NO3)2·3H2O is dissolved in deionized water, designated Solution C. Solutions B and C are sequentially added to Solution A in an ice bath, stirred for a desired period, and then transferred to a polytetrafluoroethylene autoclave for crystallization. The resulting mixture is then centrifuged, washed, dried, and calcined in a muffle furnace to obtain the SrTiCuO3 precursor.

[0051] 2) Reduction of the composite oxide precursor SrTiCuO3

[0052] Add an appropriate amount of SrTiCuO3 precursor to a certain amount of deionized water, then add a certain amount of NaOH aqueous solution, heat it to 50℃, and then drop the prepared C6H 12 O6 solution, stirred for 30 min; after the end, the obtained precipitate was centrifuged, washed with water until neutral, and dried in a vacuum drying oven to obtain Cu-SrTiCuO3-x ;

[0053] 3) Photocatalytic carbonylation reaction of ethanol and carbon dioxide

[0054] A 300W constant current xenon lamp was used as the light source. 50mg of the catalyst was placed in the center of the sample platform of the photothermal reactor. 400μL of chromatographic-grade ethanol was then dripped around the powder platform. The reactor was then sealed and the atmosphere replaced with N2. Then, CO2 was introduced at a flow rate of 40mL / min and the pressure was adjusted to 0.2MPa. The reaction was initiated by turning on the 300W Xe lamp and allowed to react for 4h. After the reaction, the gas and liquid products were collected for testing. 0.31wt% Cu2O-SrTiCuO 3-x -Ex's HCOOC2H5 generation rate can reach up to 320μmol / g / h. 3-x -Ex during the reaction of ethanol and CO2, the CO2 pressure increased to 0.4 MPa, and 343 μmol / g / h of HCOOC2H5 was obtained within 4 hours of photoreaction.

[0055] Comparative Example 1SrTiCuO 3-x -E preparation and photocatalytic carbonylation of ethanol and carbon dioxide

[0056] 1) Preparation of composite oxide precursor SrTiCuO3

[0057] Add a certain amount of ethylene glycol to a three-necked flask, stir vigorously, and add an appropriate amount of C 16 H 36 O4Ti and deionized water are mixed to obtain Solution A. Simultaneously, an appropriate amount of LiOH·H2O is dissolved in deionized water to obtain Solution B, and an appropriate ratio of SrCl2·6H2O and Cu(NO3)2·3H2O is dissolved in deionized water, designated Solution C. Solutions B and C are sequentially added to Solution A in an ice bath, stirred for a desired period, and then transferred to a polytetrafluoroethylene autoclave for crystallization. The resulting mixture is then centrifuged, washed, dried, and calcined in a muffle furnace to obtain the SrTiCuO3 precursor.

[0058] 2) Reduction of the composite oxide precursor SrTiCuO3

[0059] Add an appropriate amount of SrTiCuO3 precursor to a certain amount of deionized water, then add a certain amount of NaOH aqueous solution, heat it to 50℃, and then drop the prepared C6H 12 O6 solution, stirred for 30 min; after the end, the obtained precipitate was centrifuged, washed with water until neutral, and dried in a vacuum drying oven to obtain Cu-SrTiCuO 3-x ;

[0060] 3)Cu-SrTiCuO 3-x Surface Cu etching

[0061] Add appropriate amount of Cu-SrTiCuO 3-x Add a certain amount of deionized water, then add a certain amount of Na2S2O3 aqueous solution, stir for 1 hour, and centrifuge to obtain SrTiCuO 3-x -E sample.

[0062] 4) Photocatalytic carbonylation reaction of ethanol and carbon dioxide

[0063] The same evaluation process as in Example 1 was used to carry out SrTiCuO 3-x -E performance evaluation, no HCOOC2H5 generation.

[0064] Example 2Cu / SrTiCuO 3-x -E preparation and photocatalytic carbonylation of ethanol and carbon dioxide

[0065] 1) Preparation of composite oxide precursor SrTiCuO3

[0066] Add a certain amount of ethylene glycol to a three-necked flask, stir vigorously, and add an appropriate amount of C 16 H 36 O4Ti and deionized water are mixed to obtain Solution A. Simultaneously, an appropriate amount of LiOH·H2O is dissolved in deionized water to obtain Solution B, and an appropriate ratio of SrCl2·6H2O and Cu(NO3)2·3H2O is dissolved in deionized water, designated Solution C. Solutions B and C are sequentially added to Solution A in an ice bath, stirred for a desired period, and then transferred to a polytetrafluoroethylene autoclave for crystallization. The resulting mixture is then centrifuged, washed, dried, and calcined in a muffle furnace to obtain the SrTiCuO3 precursor.

[0067] 2) Reduction of the composite oxide precursor SrTiCuO3

[0068] Add an appropriate amount of SrTiCuO3 precursor to a certain amount of deionized water, then add a certain amount of NaOH aqueous solution, heat it to 50℃, and then drop the prepared C6H 12 O6 solution, stirred for 30 min; after the end, the obtained precipitate was centrifuged, washed with water until neutral, and dried in a vacuum drying oven to obtain Cu-SrTiCuO 3-x ;

[0069] 3)Cu-SrTiCuO 3-x Surface Cu etching

[0070] Add appropriate amount of Cu2O-SrTiCuO3-x Add a certain amount of deionized water, then add a certain amount of Na2S2O3 aqueous solution, stir for 1 hour, and centrifuge to obtain SrTiCuO 3-x -E sample.

[0071] 4) SrTiCuO 3-x -E surface loaded Cu

[0072] Add appropriate amount of SrTiCuO 3-x -E was added to a certain amount of deionized water, and then Cu(NO3)2·3H2O solution was added dropwise, and then a certain amount of NaOH aqueous solution was added. The temperature was raised to 50°C and kept warm for 5 minutes. Then, glucose solution was added dropwise and stirred at 50°C for 15 minutes. The resulting precipitate was centrifuged and washed, and dried in a vacuum drying oven to obtain Cu-SrTiCuO 3-x -E.

[0073] 5) Photocatalytic carbonylation reaction of ethanol and carbon dioxide

[0074] The same evaluation process as in Example 1 was used to carry out the 0.32 wt% Cu2O-SrTiCuO 3-x -Et performance evaluation, the generation rate of HCOOC2H5 is 112μmol / g / h.

[0075] like Figure 1 As shown, (a) is the XRD pattern of the precursor SrTiCuO3; (b) is the XRD pattern of Cu-SrTiCuO 3-x (c) is the XRD pattern of SrTiCuO in comparative example 1 3-x -E; (d) is the XRD pattern of Cu / SrTiCuO in Example 2d 3-x -XRD pattern of E.

[0076] The above description is merely a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent variation based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing ethyl formate by carbonylation of ethanol with carbon dioxide, characterized in that: In a closed photothermal reactor, a catalyst and ethanol are placed, and a reaction gas CO2 is introduced at a flow rate of 10-60 mL / min. The pressure of the photothermal reactor is adjusted to 0.1-0.4 MPa, and then a constant current xenon lamp light source is turned on to initiate a photothermal catalytic reaction. The reaction time is 1-10 hours to obtain ethyl formate, wherein the amount of the catalyst is 2-20% of the mass of the added ethanol; The catalyst is copper-doped strontium titanate (SrTiCuO) with abundant oxygen vacancies. 3-x Loaded copper, i.e. Cu-SrTiCuO 3-x ; The copper is one or both of metallic copper and cuprous oxide; The Cu-SrTiCuO 3-x The preparation method comprises the following steps: Step 1) preparing the precursor SrTiCuO3 by a hydrothermal method or a sol-gel method; Step 2) reducing the precursor SrTiCuO3 to dissolve copper; the reducing agent is one of glucose, sulfite, hydrazine hydrate, sodium ascorbate, hydrogen, and sodium borohydride; In step 1), take any one of ethylene glycol, ethanol, 1,2-propylene glycol, 1,4-butanediol, and pentaerythritol and add C 16 H 36 O4Ti, stir and mix evenly, then add water and continue stirring to obtain solution A; Mix the alkaline solution and water evenly to obtain solution B; Dissolve SrCl2•6H2O and copper salt Cu(NO3)2•3H2O in water to obtain solution C; The solutions B and C are added dropwise to the solution A in sequence under low temperature conditions. After the addition is completed, the mixture is kept warm and stirred for a period of time. The mixed solution is transferred to an autoclave, and then the autoclave is transferred to an oven for crystallization. After the crystallization is completed, the mixture is cooled to room temperature and then washed, dried and calcined to obtain the precursor SrTiCuO3.

2. The method according to claim 1, characterized in that In the photothermal reactor, a constant current irradiation xenon lamp light source is selected as the light source, the catalyst is placed at the center of the powder sample platform in the photothermal reactor, the thermocouple probe is placed in the center of the sample platform, ethanol is pipetted and dripped around the powder platform, and then the reactor is closed, and the gas in the reactor is replaced with N2 gas several times, and then the reaction gas CO2 is introduced at a flow rate of 10-60mL / min, and the pressure is adjusted to 0.1-0.4MPa. After that, the light source is turned on to start the photothermal catalytic reaction, and the reaction time is 1-10h to obtain the ethyl formate.

3. The method according to claim 1, characterized in that The SrTiCuO 3-x With abundant and tunable oxygen vacancies.

4. The method according to claim 1, wherein The SrTiCuO 3-x The morphology is one of a truncated dodecahedron, a cube, and a truncated tetradecahedron.

5. The method according to claim 1, wherein The copper and SrTiCuO 3-x The interfacial sites are abundant and adjustable.

6. The method according to claim 1, characterized in that The SrTiCuO 3-x The XRD characterization pattern shows characteristic diffraction peaks of strontium titanate structure at 2θ of 22.78°, 32.42°, 39.98°, 46.48°, 52.36°, 57.79°, 67.80 and 77.18°, which are attributed to the (100), (110), (111), (200), (210), (211), (200) and (310) crystal planes in SrTiCuO3, respectively.

Images