Research On The Preparation Of CuFe Based Catalyst For Mixed Alcohols Synthesis

Higher alcohols synthesis from CO hydrogenation is an important technology to produce chemical raw materials and fuel from coal, natural gas and biomass.Higher alcohols is green energy with high calorific value, which is one of effective methods to alleviate the current fossil fuel supply. It is of great significance to social development. Cu Fe base catalysts have advantages of high reactivity and C2+ alcohol selectivity, low reaction temperature, mild operating conditions, and low raw materials cost.This work focuses on the study of different preparation methods of catalysts, including precipitation-impregnation method, multi-impr egnations method, co-impregnation method and the modification met hod. These catalysts are characterized by XRD, H2-TPR, low-temper ature N2 adsorption, and tested for CO hydrogenation.. Several resul ts have been obtained.(1) Fe/Cu Zn Si catalysts were prepared using precipitation-impreg nation method. Precursor Cu Zn Si was obtained from precipitation reaction of the solution of Cu and Zn nitrates with K2 Si O3 solution. Crystal Fe Zn2Cu3O6.5 was observed after precursor Cu Zn Si was impr egnated with Fe(NO3)3 solution. Crystal Fe Zn2Cu3O6.5 was decompos ed into Cu O during the calcination at 400°C. It is helpful to bring forth well contacting between Cu and Fe and is beneficial to increa se the reactivity of CO hydrogenation on Fe/Cu Zn Si catalysts. CO conversion is mainly decided by Fe content in the catalysts. The di stribution of liquid products was influenced by the ratio of Cu and Zn in the catalysts. For the catalyst having equal mass of Cu and Zn, the mass of produced alcohols is more than about two-fold of the hydrocarbons and the content of C2+ alcohols is about half of the total alcohols.(2) The co-impregnation catalysts had higher reactivity than the catalysts by multi-impregnations. The order of Zn loading did not affect the catalytic reactivity, and its dispersity was far higher than that of Cu on the supporter. Smaller the distance between Cu Fe double active centerhigher the C2+ alcohol selectivity. The optimal mass ratio of Cu: Zn: Fe is 4.7:4.9:1.(3) By modifying the support with the solution of different p H value, the interactions among the support and metal ions were adjusted. That resulted in the changes of particle size and dispersion. The catalyst which was modified under the p H value of 7 was the activest among the studied catalysts. The catalyst treated by p H=4 solution showed the highest selectivity of C2+ alcohols.