考察了微波辐射条件下老化温度对Cu/ZnO/Al_2O_3催化剂在浆态床中催化CO加氢合成甲醇反应性能的影响,并采用X射线衍射、热重分析、程序升温还原、红外光谱、X射线光电子能谱、透射电镜和粒度分析等手段对催化剂及其前驱体的微观结构进行了表征.结果表明,在母液老化过程中,微波辐射有助于Cu~(2+)取代Zn_5(CO_3)2(OH)_6中的Zn~(2+),使前驱体中含有更多的(Cu,zn)_5(CO_3)_2(OH)_6物相,焙烧后催化剂的CuO-ZnO协同作用增强,CuO晶粒减小,表面Cu含量增加,从而提高了催化剂活性和稳定性.在微波辐射条件下,于80℃老化制备的催化剂活性最高,在400h浆态床合成甲醇评价期间,平均失活率仅为O.11%/d,最大时空收率为318.9mg/(g·h),比非微波辐射制得催化剂的平均失活率降低了31.2%,时空收率提高了10.1%.
Microwave irradiation was used in the aging process for the preparation of the Cu/ZnO/Al_2O_3 catalyst precursor, and the effect of aging temperature on the catalyst precursor structure and catalytic properties for slurry methanol synthesis was studied. The characterization by X-ray diffraction, FT-IR spectroscopy, derivative thermogravimetry, H_2 temperature-programmed reduction, X-ray photoelectron spec-troscopy, transmission electron microscopy, and particle size analysis showed that the microwave irradiation during the aging process promoted the substitution of Zn~(2+) in Zn_5(CO_3)_2(OH)_6 compound by Cu_O_2+ and increased the content of (Cu,Zn)_5(CO_3)_2(OH)_6 phase in the precursor. The calcined catalyst had strong interaction between CuO and ZnO, well dispersed CuO crystal particles, and high surface CuO content. The Cu/ZnO/Al_2O_3 catalyst aged at 80 ℃ under microwave irradiation exhibited the highest methanol space-time yield (STY) and more stable catalytic activity. Compared with the catalyst prepared without microwave irradiation, the methanol STY and deactivation rate of the catalyst aged at 80 ℃ under microwave irradiation were increased and decreased by 10.1 % and 31.2%, respectively.
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