CN103183346A - Method of reverse water gas shift reaction for reverse water gas shift catalyst - Google Patents

Abstract

The invention discloses a method for using a reverse water gas shift catalyst for a reverse water gas shift reaction. The method includes: (1) Activation of the catalyst: using a 60-100 mesh nickel-cerium catalyst as a reverse water gas shift catalyst, and using high-purity carbon dioxide The gas is activated on the nickel-cerium catalyst at 600-800°C for 1-2 hours; (2) Reverse water gas shift reaction: mix the activated nickel-cerium catalyst with 60-100 mesh quartz sand in a weight ratio of 1:2.5-3 Uniform, reverse water gas raw material gas, catalytic reaction at 600-800 ° C to obtain water gas. The invention selects a nickel-cerium catalyst for the reverse water gas shift reaction, and simultaneously uses high-purity carbon dioxide gas for activation, has good activation effect, has good catalytic activity and thermal stability during catalytic reaction, and has low cost.

Description

A kind of reverse water gas shift catalyst is used in the method of reverse water gas shift reaction

technical field

The invention relates to the technical field of petrochemical industry, in particular to a method for using a reverse water gas shift catalyst for a reverse water gas shift reaction. the

Background technique

The reverse water gas shift reaction equation is as follows:

CO ₂ + H ₂ = CO + H ₂ O ΔH=+41 kJ/mol

The reaction is a reversible endothermic equimolar reaction, and high temperature is beneficial to the reverse water gas shift reaction.

In recent years, in order to solve problems such as energy shortage, resource shortage, and greenhouse gas effect, countries all over the world have paid great attention to the research on the development and utilization of CO ₂ . As a carbon source, CO ₂ is considered to be an inevitable development trend for human beings to utilize carbon sources. The carbon content of CO ₂ in the atmosphere and water is ten times that of oil, natural gas and coal. Therefore, when oil, gas, and coal resources are in short supply, CO ₂ can be regarded as a good carbon source and various materials. At present, due to the rapid industrialization process of countries all over the world, the growth of energy consumption is also accelerating. The dramatic increase in _CO2 concentrations in the air caused by the annual burning of minerals leads to the so-called greenhouse effect, which heats the surface and lower atmosphere.

With the increasing greenhouse effect caused by massive CO ₂ emissions, the research on the conversion and application of CO ₂ is becoming more and more active, among which the reverse water gas shift reaction (RWGS) is considered to be one of the most promising reactions. Copper-based catalysts and Ni-based catalysts can be used for the reverse water gas shift reaction. The reverse water gas shift reaction is an endothermic reaction, so high temperature is conducive to the formation of CO. Copper-based catalysts are not suitable for high-temperature reactions due to their poor thermal stability. Adding Fe promoter can improve the catalytic activity and high temperature thermal stability of copper-based catalysts, but the activity of the catalysts still needs to be improved. The Ni/Al ₂ O ₃ catalyst showed good activity for the reverse water gas shift reaction, but a large amount of methane by-products were produced during the reaction. At the same time, the activation method of the catalyst has an important impact on its performance, which is a key factor to be considered. The existing copper-based catalysts and Ni/Al ₂ O ₃ catalysts are generally activated by nitrogen or hydrogen, as disclosed in the invention of CN101607206A Content. At present, there is no research report on the use of _CeO2- based metal catalysts for high-temperature reverse water gas shift reactions, and how to develop effective activation methods for _CeO2- based metal catalysts remains to be explored.

Contents of the invention

The purpose of the present invention is to provide a method for reverse water gas shift catalyst used in reverse water gas shift reaction. The nickel cerium catalyst is used for reverse water gas shift reaction. A special activation method is adopted, the activation effect is good, and the catalytic reaction has good catalytic activity. , thermal stability, and low cost. the

The technical solution adopted by the present invention to solve its technical problems is:

A method for using a reverse water gas shift catalyst for a reverse water gas shift reaction, the method being:

(1) Activation of the catalyst

A 60-100 mesh nickel-cerium catalyst is used as a reverse water gas shift catalyst, and the nickel-cerium catalyst is activated at 600-800°C for 1-2 hours with high-purity carbon dioxide gas.

(2) Reverse water gas shift reaction

Mix the activated nickel-cerium catalyst with 60-100 mesh quartz sand according to the weight ratio of 1:2.5-3, pass the raw material gas of water gas, and catalyze the reaction at 600-800°C to obtain water gas. The nickel-cerium catalyst is mixed with quartz sand in order to accurately and stably control the reaction temperature during the catalytic reaction and ensure the stable progress of the reaction.

Generally, the catalyst is activated by hydrogen reduction, but the present invention uses a special high-purity carbon dioxide gas to activate the nickel-cerium catalyst, and achieves a better activation effect, but the general activation method cannot effectively activate the nickel-cerium catalyst. the

Preferably, the mass percentage of nickel in the nickel-cerium catalyst is 0.25%-0.5%. Controlling the mass percentage of nickel to 0.25%-0.5% not only has better catalytic activity, but the most important thing is that high-purity carbon dioxide gas can effectively activate it, although a higher mass percentage of nickel may obtain better catalytic activity. However, when the mass percentage of nickel exceeds 0.5%, the high-purity carbon dioxide gas cannot effectively activate, and the methanation side reaction is prone to occur, which reduces the selectivity of the nickel-cerium catalyst. the

Preferably, the nickel-cerium catalyst is prepared by co-precipitation method, specifically: after mixing the cerium nitrate solution and the nickel nitrate solution evenly, using sodium hydroxide and sodium carbonate as precipitating agents, the molar ratio of sodium hydroxide and sodium carbonate is 1:1, parallel flow titration, during this process, the pH value of the precipitation solution is controlled within the range of 10±0.1, stirred at room temperature for 4-5h, aged overnight, then filtered, washed repeatedly with distilled water until pH<7.5 , dried at 80-100 °C for 20-24 h, and then calcined at 600-800 °C for 3-4 h in a muffle furnace to obtain a Ni–CeO ₂ catalyst with a mass percentage of nickel of 0.25%-0.5%.

Preferably, the purity of the high-purity carbon dioxide gas is above 99.99%. the

Preferably, in step (1), based on 1 mg of nickel-cerium catalyst, the high-purity carbon dioxide gas ventilation rate is 2.5-5 ml/min. At the same time, the amount of nickel-cerium catalyst and the ventilation rate of high-purity carbon dioxide gas can be controlled to ensure that the nickel-cerium catalyst is effectively activated and the activation effect is good. If the ventilation rate of high-purity carbon dioxide gas is lower than 2.5ml/min, it cannot be effectively activated, and if the ventilation rate of high-purity carbon dioxide gas is higher than 5ml/min, the carbon dioxide will be wasteful and increase the production cost. the

Preferably, in step (2), based on 1 mg of nickel-cerium catalyst, the ventilation rate of the reverse water gas feed gas is 5-8 ml/min. At the same time, the amount of nickel-cerium catalyst and the ventilation rate of the reverse water gas raw material gas can be controlled, so as to ensure the best catalytic conditions, maximize the performance of the catalyst, and facilitate the progress of the reverse water gas shift reaction. the

Preferably, in step (2), the composition of the reverse water gas raw material gas is 50vol.%CO ₂ , 50vol.%H ₂ .

The beneficial effect of the invention is that the nickel-cerium catalyst is selected for the reverse water gas shift reaction, and high-purity carbon dioxide gas is used for activation at the same time, the activation effect is good, the catalytic reaction has good catalytic activity and thermal stability, and the cost is low. the

Description of drawings

Figure 1 is a comparative diagram of the catalytic activity of catalysts using different activation methods. the

Detailed ways

The technical solutions of the present invention will be further specifically described below through specific embodiments and in conjunction with the accompanying drawings. the

In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or commonly used in this field. The methods in the following examples, unless otherwise specified, are conventional methods in the art. the

Preparation of Ni–CeO ₂ Catalyst (Ni-Cerium Catalyst)

It is prepared by co-precipitation method. After mixing cerium nitrate solution and nickel nitrate solution evenly, sodium hydroxide and sodium carbonate are used as precipitating agents. The molar ratio of sodium hydroxide and sodium carbonate is 1:1. In the process, the pH value of the precipitation solution is controlled within the range of 10±0.1, stirred at room temperature for 4-5h, aged overnight, then filtered, washed repeatedly with distilled water until pH<7.5, and dried at 80-100°C for 20-24 h, and then calcined in a muffle furnace at 600-800 °C for 3-4 h to obtain a Ni–CeO ₂ catalyst with a mass percentage of nickel of 0.25%-0.5%.

Taking the Ni– _CeO2 catalyst with a nickel mass percentage of 0.25% as an example, it was prepared by the co-precipitation method, and the specific steps are as follows:

Measure 217.125g/L Ce(NO ₃ ) ₃ 6H ₂ O solution 46.4ml and 9.910g/L Ni(NO ₃ ) ₂ 6H ₂ O solution 5ml and mix them to obtain nitrate solution A; Weigh 0.800g of NaOH and 2.120g of Na ₂ CO ₃ on the balance, add them into 200ml of deionized water to make precipitant solution B; titrate nitrate solution A and precipitant solution B into 400ml of stirred deionized in the water. During this process, the pH value of the precipitation solution was controlled within the range of 10±0.1 until the nitrate solution was dripped out. After stirring for 4 h at room temperature, it was allowed to stand for 12 h. Then filter, wash repeatedly with deionized water until pH<7.5, dry in a drying oven at 80°C for 24 hours, and finally put the dried precipitate in a muffle furnace for 4 hours at 600°C to obtain 0.25% Ni-CeO ₂ catalyst.

Example 1

(1) Activation of the catalyst

Use 60-100 mesh nickel-cerium catalyst with a mass percentage of 0.25% nickel as the reverse water gas shift catalyst, and use high-purity carbon dioxide gas with a purity of more than 99.99% to activate the nickel-cerium catalyst at 600 ° C for 2 hours, calculated as 1 mg of nickel-cerium catalyst , high-purity carbon dioxide gas ventilation rate at 2.5ml/min.

(2) Reverse water gas shift reaction

Mix the activated nickel-cerium catalyst with 60-100 mesh quartz sand evenly in a weight ratio of 1:2.5, and pass the raw material gas of the reverse water gas. Based on 1 mg of nickel-cerium catalyst, the ventilation rate of the raw material gas of the reverse water gas is 5ml/min. The raw material gas composition of water gas is 50vol.%CO ₂ , 50vol.%H ₂ ; water gas is obtained by catalytic reaction at 600°C.

Example 2

(1) Activation of the catalyst

Use 60-100 mesh nickel-cerium catalyst with a mass percentage of 0.5% nickel as the reverse water gas shift catalyst, and use high-purity carbon dioxide gas with a purity of more than 99.99% to activate the nickel-cerium catalyst at 800°C for 1 hour, calculated as 1 mg of nickel-cerium catalyst , high-purity carbon dioxide gas ventilation rate at 5ml/min.

(2) Reverse water gas shift reaction

Mix the nickel-cerium catalyst after the activation treatment with 60-100 mesh quartz sand according to the weight ratio of 1: 3, and feed the feed gas of reverse water gas. Based on 1 mg of nickel-cerium catalyst, the ventilation rate of feed gas for reverse water gas is 8ml/min. The raw material gas composition of water gas is 50vol.%CO ₂ , 50vol.%H ₂ ; water gas is obtained by catalytic reaction at 800°C.

the

After activating the nickel-cerium catalyst by different activation methods, the catalytic activity of the nickel-cerium catalyst for the reverse water gas shift reaction was compared. Shanghai Tianmei GC-7900 gas chromatography was used for online analysis, TDX-01 chromatographic column, and FID detection device (with methane reformer). The test results are shown in Figure 1. As can be seen from Fig. 1, adopt the method of the present invention namely high-purity carbon dioxide gas activation, the catalytic activity of nickel cerium catalyst is used for reverse water gas shift reaction is the best, and nitrogen, air, hydrogen etc. then obviously can't effectively activate nickel cerium catalyst, through these After gas activation, the catalytic activity of nickel-cerium catalysts for reverse water gas shift reaction is low.

The above-described embodiment is only a preferred solution of the present invention, and does not limit the present invention in any form. There are other variations and modifications on the premise of not exceeding the technical solution described in the claims.

 

Claims (7)

1. One kind against the current gas conversion catalyst be used for the method for gas shift reaction against the current, it is characterized in that: described method is:

   (1) activation of catalyzer

   Adopt 60-100 purpose nickel cerium catalyst as gas conversion catalyst against the current, with high-purity carbon dioxide gas at 600-800 ℃ to nickel cerium catalyst activation treatment 1-2 hour;

   (2) gas shift reaction against the current

   Nickel cerium catalyst after the activation treatment and the 60-100 purpose quartz sand part by weight according to 1:2.5-3 is mixed, logical coal gas unstripped gas against the current, 600-800 ℃ of following catalyzed reaction obtains water-gas.
2. 2. method according to claim 1, it is characterized in that: the mass percent of nickel is 0.25%-0.5% in the described nickel cerium catalyst.
3. 3. method according to claim 2, it is characterized in that: described nickel cerium catalyst adopts the coprecipitation method preparation, be specially: after cerous nitrate solution and nickel nitrate solution are mixed, be precipitation agent with sodium hydroxide and yellow soda ash, the mol ratio of sodium hydroxide and yellow soda ash is 1:1, and drip is fixed, and in this process, the pH value of precipitated liquid is controlled in 10 ± 0.1 scopes, stir 4-5h at ambient temperature, age overnight, subsequent filtration is used the distilled water repetitive scrubbing, up to pH＜7.5, at 80-100 ℃ of following dry 20-24 h, 600-800 ℃ of following roasting 3-4 h in retort furnace then, the mass percent that obtains nickel is the Ni – CeO of 0.25%-0.5% ₂Catalyzer.
4. 4. according to claim 1 or 2 or 3 described methods, it is characterized in that: the purity of described high-purity carbon dioxide gas is more than 99.99%.
5. 5. according to claim 1 or 2 or 3 described methods, it is characterized in that: in the step (1), in 1mg nickel cerium catalyst, high-purity carbon dioxide gas ventilation speed is at 2.5-5ml/min.
6. 6. according to claim 1 or 2 or 3 described methods, it is characterized in that: in the step (2), in 1mg nickel cerium catalyst, coal gas unstripped gas ventilation speed is at 5-8ml/min against the current.
7. 7. method according to claim 6 is characterized in that: in the step (2), the coal gas unstripped gas consists of 50vol.%CO against the current ₂, 50vol.%H ₂