Effect Of Structure Of Cu-Based Catalysts On Hydrogenation Of Carbon Monoxide To Higher Alcohols

For a long time,the energy problem has been one of the focuses of world attention.As a non-renewable energy source,the traditional fossil energy has a high price,accompanied by a series of environmental problems.Therefore,it is urgent to find an economical and environmentally friendly energy material to replace traditional fossil fuels.As a clean,efficient and widely used energy material,higher alcohols have attracted wide attention.The development of catalyst and process for synthesis of higher alcohols has far-reaching significance for the development of society.Previous studies of our group have found that the CuZnAl precursor prepared by sol-gel method is helpful to improve the selectivity of catalysts for the synthesis of higher alcohols from syngas,but the key structure affecting the catalytic activity is not yet clear.Therefore,on the basis of previous studies,20catalysts with distinct structural differences were obtained by changing the feeding sequence of the catalysts,compounding different metals,adding additives and changing the calcination temperature.The structure and activity of all catalysts were characterized and evaluated.In this paper,on the one hand,the influence of catalyst structure on catalyst activity was found by visual analysis of catalyst characterization data and activity evaluation results;on the other hand,linear regression analysis was used to analyze all experimental data,trying to obtain the key structural factors affecting catalyst activity.After research,the following conclusions are drawn:1.The Cu-based catalysts were prepared by sol-gel method.When CuZn solution was added to Al sol and the calcination temperature was 923 K,the CO conversion,the selectivity of C₂₊OH and total alcohol were improved.2.The structure and properties of catalysts were affected by the order of feeding sequence,the compounding of different metals,the addition of additives and the change of calcination temperature during the preparation of catalysts,However,the visual analysis of all characterization data and activity evaluation results can not obtain simple and universal conclusions about the relationship between the catalyst structure and property.3.Linear regression analysis of all characterization data and C₂₊OH selectivity showed that single factor had no significant effect on C₂₊OH selectivity.The selectivity of C₂₊OH was affected by five factors,i.e.medium alkali content,strong alkali content,hydrogen consumption,specific surface area before and after reaction.According to the positive and negative correlation of each factor,the catalyst for improving the selectivity of C₂₊OH should have the following structural characteristics:?1?Properly increasing the amount of medium alkali sites and reducing the amount of strong alkali sites;?2?Increasing the content of reducible copper species in the catalyst means increasing its hydrogen consumption;?3?Increasing the specific surface area of the catalyst before the reaction,inhibiting the further increase of the specific surface area after the reaction and obtaining more stable texture of catalyst.4.Linear regression analysis of all characterization data and C_nH_m selectivity showed that C_nH_m selectivity was only affected by hydrogen consumption.Increasing the hydrogen consumption of the catalyst could reduce the selectivity of C_nH_m in the product.