Study On The Catalyst For The Process Of Acetic Acid Hydrogenation To Ethanol

Ethanol is an important organic chemical raw material and solvent,and developed rapidly as a fuel additive in recent years.Traditional preparation methods of ethanol are fermentation of biomass and ethylene hydrate.The former method is based on grain,and the latter production line chose oil as raw material.In view of the importance of food safety in our country and the shortage of oil,the two production lines do not meet the requirements of sustainable development.The process of catalytic hydrogenation of coal-based acetic acid is simple.In the long run,as an alternative of oil,the development of liquid fuel ethanol from coal can take the advantage of coal,and will become a new developing direction of coal chemical industry.Therefore,it is of important strategic significance to our country's energy to develop catalysts with highly efficient catalytic hydrogenation to acetic acid.In this thesis,equivalent-volume impregnation was used to prepare a series of catalysts with cobalt as active component.Acetic acid was hydrogenated to ethanol under catalytic conditions in integral reactor.Acetic acid conversion and selectivity of ethanol in the catalytic reaction were chosen as catalyst evaluation index.In combination with BET,XRD,effects of different cobalt contents,different calcination temperature,and different additive Pt load on catalytic activity were investigated.The optimizing catalyst was studied under different reaction conditions to obtain the most optimal conditions.The main conclusions were:1.The effect of cobalt load on catalytic activityWhen active metal load was below 20%,the catalyst activity was low.Only a small amount of acetic acid conversed and the selectivity of ethanol was also low.But when cobalt load reached more than 20%,not only did acetic acid conversion rate increase obviously,but also ethanol had high selectivity.So the metal load between 25%and 30%was reasonable.2.Effect of calcination temperature on catalytic activityWhen the activation temperature was below 550 ?,physical property change of silica gel occurred mainly on sintering effect,calcination temperature had little impact on the silica gel form,but as the calcination temperature got higher,specific surface area and pore volume fell at the same time.The hydroxyl groups on the surface of the silica gel was removed,thus catalyst had better activity;When activation temperature rose to 600?,the sintering effect made specific surface area continue to decrease,and the high temperature crushing effect made pore size of silica gel smaller and the catalytic activity lower at the same time.So the activation temperature of 550? was suitable.3.The effect of additive Pt on catalytic activityWhen the noble metal Pt load was less than 0.5%,catalytic activity enhanced significantly.The stable impact reflected especially on the selectivity of ethanol.When the Pt load was more than 0.5%,the activity tended to increase slowly.So 0.5%could be a suitable content.According to XRD results,amorphous components decreased after the addition of Pt.Alloy CoSi displayed a more distinct diffraction peak.4.Effect of reaction conditions on 25%Co-0.5%Pt/SiO2 and optimum conditionThe effect of reaction temperature(T),reaction pressure(P),acetic acid liquid space velocity(LHSV),and hydrogen-acetic acid mole ratio on acetic acid conversion and selectivity of ethanol under the catalyst condition of 25%Co-0.5%Pt/SiO2 was investigated.The optimum operation condition obtained through orthogonal test was T 290?,P 7.0 MPa,LHSV 0.5 h-1,and n 28.