Preparation method of copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas
阅读说明：本技术 一种用于合成气制低碳醇的铜钴基催化剂的制备方法 (Preparation method of copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas ) 是由 王亮 李亚斐 郑长征 刘斌 丁涛 惠盼婷 南柯媚 黄志刚 于 2019-09-19 设计创作，主要内容包括：本发明公开了用于合成气制低碳醇的铜钴基催化剂的制备方法,具体按照以下步骤实施：步骤1,将碳纳米管置于浓硝酸中进行处理,再蒸涂于碳纸上,自然晾干,得到阴极电极材料；步骤2,在离子水中加入无水硫酸铜、七水硫酸钴、柠檬酸钠和硫酸钠,搅拌均匀,得到溶液a,再对pH值进行调节,调节后置于恒温水浴锅中,得到电解液；步骤3,将阴极电极材料和阳极电极材料置于电解液中,采用数控恒电流电镀电源将其连接,进行电解,得到铜钴基催化剂样品；步骤4,将铜钴基催化剂样品冲洗至容器中,进行干燥、焙烧、压片、研磨、筛分,即得到铜钴基催化剂。本发明制备的催化剂表面疏松多孔,比表面积较大,活性组分高度分散,催化效果良好。(The invention discloses a preparation method of a copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas, which is implemented according to the following steps: step 1, placing carbon nanotubes in concentrated nitric acid for treatment, then steaming and coating the carbon nanotubes on carbon paper, and naturally airing to obtain a cathode electrode material; step 2, adding anhydrous copper sulfate, cobalt sulfate heptahydrate, sodium citrate and sodium sulfate into ionized water, uniformly stirring to obtain a solution a, adjusting the pH value, and placing the solution in a constant-temperature water bath kettle to obtain an electrolyte; step 3, placing the cathode electrode material and the anode electrode material in an electrolyte, connecting the cathode electrode material and the anode electrode material by adopting a numerical control constant current electroplating power supply, and electrolyzing to obtain a copper-cobalt-based catalyst sample; and 4, washing the copper-cobalt-based catalyst sample into a container, drying, roasting, tabletting, grinding and screening to obtain the copper-cobalt-based catalyst. The catalyst prepared by the method has loose and porous surface, large specific surface area, highly dispersed active components and good catalytic effect.)
1. A preparation method of a copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas is characterized by comprising the following steps:
step 1, placing carbon nanotubes in concentrated nitric acid for treatment, then steaming and coating the carbon nanotubes on carbon paper, and naturally airing to obtain a cathode electrode material;
step 2, adding anhydrous copper sulfate, cobalt sulfate heptahydrate, sodium citrate and sodium sulfate into deionized water, uniformly stirring to obtain a solution a, adjusting the pH value of the solution a, and placing the solution a into a constant-temperature water bath kettle to obtain an electrolyte;
step 3, placing the cathode electrode material and the anode electrode material obtained in the step 1 into the electrolyte obtained in the step 2, connecting the cathode electrode material and the anode electrode material by adopting a numerical control constant current electroplating power supply, and electrolyzing to obtain a copper-cobalt-based catalyst sample;
and 4, washing the copper-cobalt-based catalyst sample obtained in the step 3 into a container, drying and roasting, tabletting and grinding after the drying, and screening by using a 40-60-mesh sieve to obtain the copper-cobalt-based catalyst.
2. The method for preparing the copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas according to claim 1, wherein the carbon nanotube treatment process in the step 1 is as follows: heating the carbon nano tube in concentrated nitric acid to 80-100 ℃, refluxing for 4-6 h, filtering and washing to be neutral after the end, drying overnight in a drying oven at 110 ℃ for 10h, grinding, and screening by using a 200-mesh sieve for later use.
3. The preparation method of the copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas according to claim 1, wherein the evaporation coating process in the step 1 is as follows: weighing 0.05-0.06 g of phenolic resin and 0.06-0.07 g of polyvinylidene fluoride, and adding into 20-25 ml of N, N-dimethylPerforming ultrasonic oscillation in acetamide for 15-25 min, adding 0.25-0.3 g of treated carbon nano tube, continuing ultrasonic oscillation for 8-12 min to obtain a mixed solution, using a titanium plate with the size of 12 x 12cm to be placed above a constant-temperature water bath kettle at 80 ℃, and then placing a titanium plate with the size of 100-144 cm in an overhead manner2The carbon paper is placed on a titanium plate, the mixed solution is uniformly dripped on the surface of the carbon paper by a layer by a burette and is evaporated to dryness, the dripping and evaporating processes of the mixed solution are circulated until the dripping of the mixed solution is finished, and the mixed solution is naturally dried, so that the evaporation coating is finished.
4. The method for preparing the copper-cobalt-based catalyst for preparing the lower alcohol from the synthesis gas as claimed in claim 1, wherein the volume of the deionized water in the step 2 is 1L; the concentration of anhydrous copper sulfate in the solution a is 5-10 g/L, the concentration of cobalt sulfate heptahydrate is 30-50 g/L, the concentration of sodium citrate is 40-60 g/L and the concentration of sodium sulfate is 20 g/L; adjusting the pH value to 3.5-5.5, wherein a sulfuric acid solution or a sodium hydroxide solution is adopted as a solution for adjusting the pH value; the temperature of the water bath is 45-55 ℃.
5. The method for preparing the copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas according to claim 1, wherein the current density of electrolysis in the step 3 is 2.1-3.7A/dm2The electrolysis time is 20-40 min.
6. The method for preparing the copper-cobalt-based catalyst for preparing the low-carbon alcohol from the synthesis gas according to claim 1, wherein the anode electrode material in the step 3 is a graphite plate.
7. The preparation method of the copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas according to claim 6, wherein the thickness of the carbon paper and the graphite plate is 2 mm.
8. The method for preparing the copper-cobalt-based catalyst for preparing the low-carbon alcohol from the synthesis gas as claimed in claim 1, wherein the drying temperature in the step 4 is85-120 ℃ for 8-10 h; calcined in N2The reaction is carried out under the atmosphere, the temperature is 350-450 ℃, and the time is 3.5-4.5 h.
9. The preparation method of the copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas according to claim 1, wherein the specific surface area of the carbon nanotubes in the step 1 is 100-120 m2A pipe diameter of 30 to 50nm and a pipe length of g<10 μm, and a bulk density of 0.12-0.25 g/cm3The carbon content is more than or equal to 98 percent.
Technical Field
The invention belongs to the technical field of chemical catalyst preparation, and particularly relates to a preparation method of a copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas.
Background
Because of the characteristics of energy structure 'rich coal, poor oil and less gas' in China, the strategy of 'coal replacing petroleum' is greatly promoted by the government of China in recent years, and synthesis gas (CO + H)2) Synthesized by using C as raw material under the action of catalyst1～C5The low-carbon mixed alcohol mainly containing alcohols has wide application prospect. The low carbon alcohol can be used as chemical raw material and chemical product, and can also be used as substitute fuel and clean gasoline additive.
The catalysts for preparing low-carbon alcohol from synthesis gas reported at present can be generally divided into ① modified Cu-based methanol catalysts, ② modified Fischer-Tropsch (F-T) synthesis catalysts, ③ Mo-based catalysts and ④ precious metal Rh-based catalysts, wherein the Cu-Co-based catalysts in the modified Fischer-Tropsch catalysts can react under mild reaction conditions (general reaction pressure is 3-6 MPa, reaction temperature is 220-330 ℃), and have relatively high low-carbon alcohol selectivity and catalytic activity, and are considered to have the greatest industrial prospect.
The coprecipitation method, the impregnation method and the sol-gel method, which are reported in the literature and the patents, cause the defects to a great extent, and show that different preparation methods have great influence on the reaction activity of the catalyst for preparing the low-carbon alcohol from the synthesis gas.
Disclosure of Invention
The invention aims to provide a preparation method of a copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas, which solves the problems of low activity and low alcohol selectivity of the copper-cobalt-based catalyst for preparing low-carbon alcohol in the prior art.
The technical scheme adopted by the invention is that the preparation method of the copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas is implemented according to the following steps:
step 1, placing carbon nanotubes in concentrated nitric acid for treatment, then steaming and coating the carbon nanotubes on carbon paper, and naturally airing to obtain a cathode electrode material;
step 3, placing the cathode electrode material and the anode electrode material obtained in the step 1 into the electrolyte obtained in the
and 4, washing the copper-cobalt-based catalyst sample obtained in the step 3 into a container, drying and roasting, tabletting and grinding after the drying, and screening by using a 40-60-mesh sieve to obtain the copper-cobalt-based catalyst.
The invention is also characterized in that:
the treatment process of the carbon nano tube in the step 1 comprises the following steps: heating the carbon nano tube in concentrated nitric acid to 80-100 ℃, refluxing for 4-6 h, filtering and washing to be neutral after the end, drying overnight in a drying oven at 110 ℃ for 10h, grinding, and screening by using a 200-mesh sieve for later use.
The steam coating process in the step 1 comprises the following steps: weighing 0.05-0.06 g of phenolic resin and 0.06-0.07 g of polyvinylidene fluoride, adding the phenolic resin and the polyvinylidene fluoride into 20-25 ml of N, N-dimethylacetamide, carrying out ultrasonic oscillation for 15-25 min, adding 0.25-0.3 g of treated carbon nano tube, continuing the ultrasonic oscillation for 8-12 min to obtain a mixed solution, using a 12 x 12cm titanium plate to be placed above a 80 ℃ constant-temperature water bath kettle in an overhead manner, and then placing 100-144 cm in size2The carbon paper is placed on a titanium plate, the mixed solution is uniformly dripped on the surface of the carbon paper by a layer by a burette and is evaporated to dryness, the dripping and evaporating processes of the mixed solution are circulated until the dripping of the mixed solution is finished, and the mixed solution is naturally dried, so that the evaporation coating is finished.
The volume of the deionized water in the
The current density of electrolysis in the step 3 is 2.1-3.7A/dm2The electrolysis time is 20-40 min.
And 3, taking the anode electrode material as a graphite plate.
The thickness of the carbon paper and the graphite plate is 2 mm.
The drying temperature in the step 4 is 85-120 ℃, and the drying time is 8-10 h; calcined in N2The reaction is carried out under the atmosphere, the temperature is 350-450 ℃, and the time is 3.5-4.5 h.
The specific surface area of the carbon nano tube in the step 1 is 100-120 m2G, pipe diameter of 30 &50nm, tube length<10 μm, and a bulk density of 0.12-0.25 g/cm3The carbon content is more than or equal to 98 percent.
The invention has the beneficial effects that: the prepared copper-cobalt-based catalyst has a stable structure, the active components are uniformly loaded and highly dispersed, the activity of the catalyst on the preparation of low-carbon alcohol from synthesis gas is high, the CO conversion rate can reach 38%, and the total alcohol selectivity can reach 47%. The electrodeposition preparation method adopted by the invention has the advantages of simple process, easily controlled deposition conditions and environmental protection.
Drawings
Fig. 1 is an SEM image of a manufacturing method of the present invention, in which fig. 1(a) is an SEM image of example 1, fig. 1(b) is an SEM image of example 2, fig. 1(c) is an SEM image of example 3, fig. 1(d) is an SEM image of example 4, fig. 1(e) is an SEM image of example 5, fig. 1(f) is an SEM image of example 6, and fig. 1(g) is an SEM image of example 7.
Detailed Description
The present invention will be described in detail with reference to the following embodiments.
The invention relates to a preparation method of a copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas, which is implemented according to the following steps:
step 1, placing a carbon nano tube in concentrated nitric acid, heating to 80-100 ℃, refluxing for 4-6 hours, filtering and washing to be neutral after the completion, drying overnight in an oven at 110 ℃ for 10 hours, grinding, sieving by using a 200-mesh sieve, then coating on carbon paper by evaporation, and naturally airing to obtain a cathode electrode material;
wherein, the process of steaming and coating is as follows: weighing 0.05-0.06 g of phenolic resin and 0.06-0.07 g of polyvinylidene fluoride, adding the phenolic resin and the polyvinylidene fluoride into 20-25 ml of N, N-dimethylacetamide, carrying out ultrasonic oscillation for 15-25 min, adding 0.25-0.3 g of treated carbon nano tube, continuing the ultrasonic oscillation for 8-12 min to obtain a mixed solution, using a 12 x 12cm titanium plate to be placed above a 80 ℃ constant-temperature water bath kettle in an overhead manner, and then placing 100-144 cm in size2The carbon paper is placed on a titanium plate, the mixed solution is uniformly dripped on the surface of the carbon paper by a dropper to be evaporated to dryness, and the processes of dripping and evaporating to dryness of the mixed solution are circulatedAnd naturally airing until the mixed solution is dripped, and finishing the coating by steaming.
The specific surface area of the carbon nano tube is 100-120 m2A pipe diameter of 30 to 50nm and a pipe length of g<10 μm, and a bulk density of 0.12-0.25 g/cm3The carbon content is more than or equal to 98 percent;
wherein the concentration of anhydrous copper sulfate in the solution a is 5-10 g/L, the concentration of cobalt sulfate heptahydrate is 30-50 g/L, the concentration of sodium citrate is 40-60 g/L and the concentration of sodium sulfate is 20 g/L;
step 3, placing the cathode electrode material and the anode electrode material obtained in the step 1 into the electrolyte obtained in the
wherein, the anode electrode material is a graphite plate; the carbon paper and the graphite plate are both 2mm in thickness, the graphite plate is a commercially available graphite plate, and the carbon paper and the graphite plate are used after being soaked in a dilute alkali solution for 30min and washed clean by deionized water before use;
step 4, washing the copper-cobalt-based catalyst sample obtained in the step 3 into a container, drying the sample at 85-120 ℃ for 8-10 h, and heating at the temperature of 5 ℃/min under N2Roasting for 3.5-4.5 hours in an atmospheric tubular furnace at the roasting temperature of 350-450 ℃, tabletting and grinding by using a table type tablet machine after the roasting is finished, and screening by using a 40-60-mesh screen to obtain the copper-cobalt-based catalyst.
The specific process of the performance test of the copper-cobalt-based catalyst for preparing low-carbon alcohol from synthesis gas is as follows:
the performance test of the copper-cobalt-based catalyst for preparing the low-carbon alcohol from the synthesis gas is carried out on an experimental device for synthesizing the low-carbon alcohol by controlling coal gasification through DCS (distributed control System)The tubular reactor with the inner diameter of phi 12mm multiplied by 600mm is filled with 0.5g of copper-cobalt-based catalyst, and the volume ratio of the copper-cobalt-based catalyst is 6: 1H2/N2Reducing the mixed gas at 470 ℃ for 6h, then reducing the temperature of the reactor to 450 ℃, and switching to a gas-liquid separator with the volume ratio of 2: 1H2The synthesis gas of/CO is reacted after the temperature and the gas pressure are stabilized, the reaction tail gas discharged from the outlet of the reactor is immediately unloaded to the normal pressure, the reaction tail gas is directly sent to a six-way valve of a gas chromatograph of Tianmei GC-7890 II for sampling through a heat insulation pipeline, a Thermal Conductivity Detector (TCD) is used for on-line detection, a liquid phase product is sampled once every 6 hours until no liquid is generated, the liquid phase product is injected into the gas chromatograph of Tianmei GC-7890 II after being sampled by an injector, and the analysis is carried out by a hydrogen flame detector (FID).