Hydrothermal Synthesis Of Alcohol Dehydrogenation Copper Silicate Catalyst

In this paper,copper silicate catalyst with stable structure was prepared by hydrothermal crystallization method.The influence of the ratio of ammonia to copper,the ratio of copper to silicon,the hydrothermal time,the addition of surfactant on the structure and catalytic performance of dehydrogenation of ethanol to acetaldehyde of the catalyst was investigated.The results are listed as follows:(1)With the increase of the ratio of ammonia to copper,the amount of copper silicate increased firstly and then decreased.and the excessive amount of NH4+ leads to the collapse of copper silicate skeleton.When the ratio of ammonia to copper is 16:1,the catalyst exhibit the highest reduction ratio of Cu2+.The results show that when the ratio of copper to silicon is 1:1.5,there is no obvious crystalline phase of copper silicate on the surface of the catalyst,and the morphology and structure are relatively poor,and when the ratio of copper to silicon is 1.5:1,the species of CuO and Cu2O are detected.When the ratio of copper to silicon is 1:1,the crystalline phase of copper silicate is detected on the surface,and the catalyst forms a tubular structure.The study of hydrothermal time shows that,with the prolongation of hydrothermal time,the catalyst surface gradually changes from amorphous structure to tubular structure and finally the skeleton collapses.And the specific surface area,pore volume and copper content of the catalyst were increased first and then decreased.When the hydrothermal time was 12 h,the catalyst exhibits larger specific surface area,higher copper content,better tubular structure,higher catalytic activity and anti-sintering ability.At this time,the conversion rate of ethanol is 50.7%,the selectivity of acetaldehyde is 70.8%.After deactivated treatment of the catalyst at 400 ?,the ethanol conversion remained at 433%,and the selectivity of acetaldehyde was 62.2%.(2)The effects of CTAB,oleic acid,oleic acid,polyethylene glycol and sodium dodecyl benzene sulfonate on the morphology of the catalyst were investigated.The results showed that the catalyst prepared by oleamine exhibits a small particle size and a tubular structure.With the increase of the content of oleamine,the specific surface area of the catalyst increased firstly and then decreased.When the content of oleamine was 1g,hollow sphere catalyst was formed.At this time,the conversion of ethanol and selectivity of acetaldehyde were 51.1%and 83.2%respectively.