Study On Vapor-phase Ethanol Carbonylation On Ni-Zn/C Catalyst At Atmospheric Pressure

In the situation of propionic acid depending on importation in China, a novel heterogeneous Ni-Zn/C catalyst was investigated for vapor-phase carbonylation of ethanol to propionic acid and ethyl propionate under atmospheric pressure. In this work, catalyst perparation and characterization, reaction techniques and kinetics were studied.1.The catalyst support were characterizated by surface structure, crystalline structure, surface acidity, adsorption property and pore structure. The optimum of carbonylation support and active metal were water washed activated carbon and nickel, respectively. Adding zinc significiently promoted the activity and selectivity of ethanol carbonylation.The optimum of catalyst component was 5wt% Ni-3.5wt% Zn, the optimum of metal loading sequence was the first impregnating Zn, and then impregnating Ni.2. Reaction techniques of ethanol carbonylation were evaluated. The optimum reaction conditions were chosen as following: reaction temperature: 250 ℃; space velocity of ethanol:0.83ml/gCat.h; CO/C₂H₅OH/C₂H₅I=2/1/0.1(mol). Under a forementioned conditions, ethanol conversion of 98%, carbonylation selectivity of 70%, and a yield of 68.5%(mol) were obtained. Take propionic acid as purpose product, the optimum reaction conditions were also examined: reaction temperature: 260 ℃ ; space velocity of ethanol: 0.83ml/gCat.h;CO/C₂H₅OH/C₂H₅I=4/1/0.1(mol), in this conditions, the content of propionic acid exceeded 99% in the carbonylation products, the yield of propionic acid exceeded 65%(mol).3. A new method of temperature-programmed-calcination(TPC) was presented, thermal-decomposed models and kinetic equations were employed to characterize the calcination process of catalysts. The reduction process of catalyst was analyzed by TPR, a new equation of calculating [H]m was presentedto study reduction kinetics of catalyst. The adsorption sites of catalyst surface were characterized by TPD, and three adsorption sites (α , β , γ ) of CO wereexamined. Relationships between CO adsorption and carbonylation were discussed. Zn strengthened CO adsorption in active site of carbonylation to...