Study On Bifunctional Catalyst Cu-ZnO/SAPO-34for One-step Synthesis Of Light Hydrocarbons From Syngas

The effective transformation of syngas to light hydrocarbons has been gaining sustainably increasing attention. The industrial production route includes methanol synthesis and methanol dehydration. One-step synthesis is a novel route to combine two reactions on the bifuntional catalyst, which contributes to shorter process and lower investment. Nowadays, the research of one-step synthesis rarely focused on light hydrocarbons synthesis. The development of effective bifunctional catalysts is critical for one-step synthesis. This thesis mainly studied on the bifunctional catalysts CuO-ZnO/SAPO-34for one-step syntheisis of light hydrocarbons.The main research contents are as follows:(1) Two series of bifunctional catalysts CuO-ZnO/SAPO-34were prepared by isometric impregnation method and milling calcination method, namely Ⅱ-xCZ/S and MC-xCZ/S. All the samples were characterized by SEM, XRD, BET, H2-TPR and NH3-TPD techniques.(2) The catalyst samples with different composition ratios have been investigated in the one-step transformation of syngas to light hydrocarbons. The results indicate that the preparation methods have significant effect on the catalytic performance. Though both two series catalysts could realize one-step transformation, MC-xCZ/S samples facilitated higher syngas convertion while Ⅱ-xCZ/S samples had higher light hydrocarbons selectivity, since Ⅱ-xCZ/S displayed a smaller amount of metallic solid solution, a stronger interaction between the loaded metallic particles and supportive zeolites, more appropriate acidity strength as well.(3) Acid pretreatment was applied to modify SAPO-34zeolite before isometric impregnation for loading CuO and ZnO particles. With the0.05mol/L oxalic acid, SAPO-34obtained the mesopores with average pore diameter of3.3nm. Compared with the Ⅱ-xCZ/S sample, the CuO particles on xCZ/S-c sample were easier to be reduced, and the acid sites were weaker, which both leaded to the difference in catalytic performance. The CO conversion and the selectivity of light hydrocarbons were increased lightly while WSG were improved as well.