焙烧温度对二甲醚水蒸气重整制氢Cu/ZnO/Al_2O_3/Cr_2O_3+H-ZSM-5双功能催化剂性能的影响

Effect of calcination temperature on properties of Cu/ZnO/Al_2O_3/Cr_2O_3+H-ZSM-5 bi-functional catalysts for steam reforming of dimethyl ether

采用共沉淀耦合机械混合法制备了Cu/ZnO/Al2O3/Cr2O3+H-ZSM-5双功能催化剂,并用于二甲醚水蒸气重整制氢反应,结合热重、傅里叶红外光谱、XRD、BET、H2-TPR表征,考察了焙烧温度对Cu/ZnO/Al2O3/Cr2O3催化剂物理化学性质及双功能催化剂催化性能的影响。研究结果表明,400℃焙烧时,析出CuO粒子的同时伴有尖晶石相,进而在反应过程中对金属铜粒子起到良好的隔离作用。而焙烧温度较低时,催化剂分解不完全,催化剂活性位较少。焙烧温度大于500℃时,CuO粒子发生二次团聚,同时尖晶石相大量生成,造成催化剂活性位减少,活性较低。合适的焙烧温度为400℃,此时二甲醚转化率为92.9%,氢气收率可达到76.5%,具有较好的反应效果。

The Cu/ZnO/Al2O3/Cr2O3＋H-ZSM-5 performances for hydrogen production during dimethyl ether steam reforming（DME SR） were investigated,which was prepared by the co-precipitation coupling with mechanical mixing method.Meanwhile,the effect of calcination temperature on the physicochemical properties of catalysts were studied by thermogravimetry,Fourier transform infrared spectroscopy,X-ray diffraction,Brunauer-Emmett-Teller,and H2 temperature-programmed reduction.It was revealed that Cu/ZnO/Al2O3/Cr2O3 catalyst was decomposed at 400 ℃ to form CuO and sponel phase that played a key role in separating the Cu during the reaction.Under lower calcination temperatures,the catalyst was incompeletely decomposed.Increasing the calcination temperature to over 500 ℃ caused severe sintering of CuO and facilitated the formation of spinel phase,which led to a significant decrease in the number of active sites.When the calcination temperature was controlled at 400 ℃,the biggest DME conversion rate of 92.9% and hydrogen yield of 76.5% was reached.