Study On In Based Catalyst For Hydrogenation Of CO₂ To Methanol

The climate and environment problems caused by CO2 have aroused great concern of the whole society.Among many CO2 emission reduction technologies,the application of CO2 hydrogenation technology to fuel and chemicals is one of the effective CO2 emission reduction technologies.Methanol is a carrier of hydrogen and can be transported over long distances.Hydrogenation of carbon dioxide to methanol can realize the recycling of hydrocarbon source.Therefore,replacing CO with CO2 as raw material can greatly promote the carbon cycle,which is one of the effective ways to solve environmental problems and energy problems.However,CO2 molecules are extremely stable,so it is necessary to use catalysts to reduce the CO2 activation energy barrier to achieve efficient CO2 conversion.This paper is devoted to the research of catalyst for CO2 hydrogenation to methanol.A series of In-base composite catalysts were prepared by coprecipitation method and sol-gel method,and the effects of loading capacity and reaction temperature on the properties of the catalysts were investigated.The main research contents are as follows:(1)The performance of CO2 hydrogenation to methanol with InZnZr composite catalyst was studied.It was found that the activity of 42%InZnZr composite catalyst was the best at 300℃,the conversion rate of CO2 was 11%and the selectivity of methanol was 80.05%.SEM showed that compared with ZnZrOx and In2O3 alone,the surface of 42%InZnZr composite catalyst was rougher and had more holes and defects.XPS analysis showed that the oxygen vacancy content of 42%InZnZr catalyst was the highest.Therefore,it is speculated that the synergistic effect of In with Zn and Zr can promote the generation of oxygen vacancy and facilitate the reaction activity.H2-TPR showed that the reduction performance of InZnZr catalyst was between ZnZrOx and In2O3.It can be inferred that the appropriate reduction performance is conducive to the hydrogenation of CO2.CO2-TPD showed that the temperature of the desorption peak of 42%InZnZr was lower than that of InZnZr of other proportions,indicating that the binding ability between the catalyst and CO2 was weakened,so that CO2 molecules could easily desorbed from the surface of the catalyst,thus promoting the catalytic reaction.In situ DRIFTS,H3CO*stably exists on the surface of hydrogenation reaction with CO2.On 42%InZnZr catalyst,the reaction path of CO2 hydrogenation to methanol is better than formate path.(2)The performance of CO2 hydrogenation to methanol with In2O3/TNTs composite catalyst was studied.It was found that the 1:0.2 In2O3/TNTs composite catalyst pretreated with H2 has the best activity at 280℃ the conversion rate of CO2 is 9.14%,and the selectivity of methanol is 80%.SEM showed that the composite catalyst was a microstructure supported by nanoparticles on nanotubes,indicating that In2O3 was successfully combined with TNTs,and TNTs was conducive to better dispersion of metal oxides.BET showed that the specific surface area of all composite catalysts increased with the increase of TNTs load.H2-TPR analysis showed that with the increase of TNTs load,the interaction between catalyst and support became weaker,which indicated that the reducing power of catalyst became stronger.That is,the introduction of TNTs is beneficial to increase the reduction performance of the catalyst.CO2-TPD showed that for a series of In2O3/TNTs composite catalysts,the number of medium-strong alkaline sites in the 1:0.2 In2O3/TNTs composite catalyst was the largest,which was conducive to the adsorption of CO2.