[CuO-ZnO-Al2O3]/[HZSM-5]核壳双功能催化剂的制备、结构及其CO2+H2直接合成二甲醚反应性能

利用水热合成法制备了一系列不同晶化时间的核壳结构双功能催化剂CuO-ZnO-Al₂O₃]/HZSM-5],通过X射线衍射(XRD)、扫描电镜(SEM)和能量分散谱(EDS)对催化剂结构进行了表征,并考察了核壳催化剂CO₂加氢直接合成二甲醚的反应性能。结果表明,通过水热合成法可在甲醇合成催化剂CuO-ZnO-Al₂O₃表面包覆一层完整的HZSM-5分子筛膜,形成核壳结构,并且调节晶化时间可以控制分子筛晶粒尺寸及膜厚。与物理混合法制备的传统双功能催化剂相比,核壳结构催化剂合成二甲醚的选择性显著提高,其中晶化时间为3d的催化剂反应性能最为理想,CO₂转化率为38.9%,二甲醚选择性达到77.0%。

Preparation,Structure and Performance of [CuO-ZnO-Al2 O3]/[HZSM-5] Core-Shell Bifunctional Catalysts for One-Step Synthesis of Dimethyl Ether from CO2+H2

A series of core-shell bifunctional catalysts CuO-ZnO-Al2O3]/HZSM-5] for one-step synthesis of dimethyl ether from CO2 hydrogenation were prepared by a hydrothermal synthesis method,and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectroscopy(EDS).The catalyst has a core-shell structure with an integral and compact shell of HZSM-5 coated on the surface of a pre-shaped CuO-ZnO-Al2O3 pellet.The crystallite size and thickness of the zeolite shell can be controlled by the crystallization time.Compared with the mechanically mixed catalyst,the core-shell catalyst shows much higher selectivity for dimethyl ether synthesis from CO2 + H 2.The core-shell catalyst with a crystallization time of 3 d shows the best catalytic performance,with a CO2 conversion of 38.9% and a dimethyl ether selectivity of 77.0%.