A new core-shell-like capsule catalyst with SAPO-46 zeolite shell encapsulated Cr/ZnO for the controlled tandem synthesis of dimethyl ether from syngas

A simply manipulated approach, named "physically coating" (PhyC), was initially developed to construct a new core-shell-like silicoaluminophosphate (SAPO-46) encapsulated Cr/ZnO capsule catalyst. The method reported here is very accessible, repeatable, and scalable, overcoming much practical problems faced by the industrial preparation of zeolite capsule catalysts through traditional hydrothermal synthesis way. With the assistance of this method, the core catalyst Cr/ZnO is completely safe from the destruction caused by heat treatment and chemical corrosion. The one-step reaction process of syngas to dimethyl ether synthesis (STD reaction) is selected as the application to test the catalytic activity of the prepared capsule catalyst Cr/ZnO-SAPO46-PhyC. In comparison with the simple mixing structure of the traditional mixture catalyst, the specific core-shell structure of this new zeolite capsule catalyst has an obvious confinement effect on the controlled synthesis of DME from syngas. At the same time, it can effectively suppress the side reaction of the further dehydration of DME generating other by-products such as alkane/alkene.