Study On The Synthesis Of Ethanoland Methanol From Syngas Over Cu-Zn-Si(Al) Catalyst Prepared By Complete Liquid-phase Method

With oil, natural gas and other non renewable resources been utilized, theenvironmental pollution and energy issues are serious. So the research of greenenergy is a matter of great urgency. Ethanol and methanol with many advantagesmake them become the good alternative energy sources of oil. They play animportant role in order to alleviate the shortage of liquid fuel in China.Because of the wide range of raw materials, the study on the COhydrogenation for the synthesis of methanol ethanol and MAS has been paidmore attention. In order to the special environment of slurry-state reaction forthe DME synthesis, the complete liquid-phase method was put forward by ourgroup. It was used to prepare the Cu-based catalyst for synthesis of ethanol andmethanol from CO hydrogenation. Research results show that the dispersion ofcopper species, the stability of Cu+species and less surface acidity in catalyst isthe key of ethanol synthesis from syngas.Under this background, we proposed the ammonia-evaporation and complete liquid-phase method for the preparation of Cu-Zn-Si catalyst. Theinfluences of the addition of ammonia and silicon content for the catalystperformance were investigated. The effect of the addition of chrysocolla madeby self to Cu-Zn-Si-Al catalyst was studied. The effects of the amount andposition of PEG-600for the Cu-Zn-Si catalyst prepared by the completeliquid-phase method were studied. Catalyst were characterized by XRD,N2-adsorption, H2-TPR, XPS,NH3-TPD-MS and so on. The main researchconclusions are listed as follows:1. The addition of a certain amount of PEG-600can enhance specificsurface area, the content of Cu on the surface and Cu dispersion degree, thus itcan further improve the performance of catalysts. With the increasing amount ofPEG-600, the activity of the catalysts and selectivity of methanol are decreasedbut the ethanol production is increased. The selectivity of ethanol reaches23%.2. When the catalyst with n(ammonia)/n(Cu2+)=5prepared by theammonia-evaporation and complete liquid-phase method, it showed goodactivity and selectivity to ethanol.Because the presence of Cu+species isdifficult to be reduced and the copper species of catalyst has the best dispersion.The increasing amount of ammonia is not conducive to the dispersion of thecopper species, and the catalytic activity and selectivity of ethanol weredecreased.3. In the process of preparation of Cu-Zn-Si catalyst,the increasing contentof silicon will increase the dispersion of Cu and ZnO species in the catalyst and increase the surface area of the catalyst. The reaction activity of the catalyst wassignificantly improved, but the selectivity of DME was reduced.4. The addition of self-made chrysocolla is against catalyst reactionactivity. The different position of chrysocolla has a large effect on the structureand properties of catalysts. When adding the aluminum-sol, it is beneficial toimprove the dispersion of the copper species, increase the surface area of thecatalyst; adding Cu-Zn alcohol solution, catalyst with a little amount of weakacid sites and medium strong acid sites is favorable for the ethanol synthesis.5. When catalyst has a less weak acid and medium strong acid sites, it isbeneficial to the formation of ethanol, also can increase the catalyst of thecarbon chain growth ability.