Bifunctional Capsule Catalyst of Al2O3@Cu with Strengthened Dehydration Reaction Field for Direct Synthesis of Dimethyl Ether from Syngas

Direct conversion of syngas to dimethyl ether (DME) using bifunctional catalysts is a promising way to meet the current industrial demands. However, the spatial design of the bifunctional catalyst still remains a challenge. Here, we report a novel bifunctional capsule catalyst of Al2O3@10Cu, synthesized by a simple surface infiltration method. It is different from the traditional capsule catalysts with the core for methanol synthesis and the shell for methanol dehydration. The Al2O3@10Cu employs an opposite strategy that uses the shell for methanol synthesis while the core for methanol dehydration. Our characterization results clearly demonstrate that the capsule Al2O3@10Cu possesses a more uniform Cu–Al2O3 shell and a lower reduction temperature than other reference catalysts. Further, in the direct DME synthesis from syngas, the Al2O3@10Cu with the uniform shell exhibits much higher CO conversion and DME selectivity than the conventional powder-based Cu/Al2O3–P catalyst. The present work offers a new spatially confined model for the direct DME synthesis from syngas.