Since the first report of selective carbonylation of dimethyl ether (DME) over zeolite catalysts by Iglesia and his colleagues in 2006, this reaction has been attracting great attention in the field of heterogeneous catalysis, because it offers an effective way to enhance the value of C1 chemicals via the formation of C-C bonds.Mass transfer is an important factor in zeolite catalytic reaction. Relative to the well-known intracrystalline transport resistance, the significance of surface barriers on catalytic performance of zeolites has not been well recognized.

Herein, it’s found that the DME carbonylation reaction can be governed by surface barriers on zeolites, affecting both the catalyst activity and stability. The two MOR zeolites used for the investigation were synthesized by different organic structure directing agents (OSDAs). They possess similar Si/Al ratios, diffusion lengths, Al distribution and acidity, but quite different diffusion properties. Sample MOR-C with severe transport limitations exhibits inferior apparent activity (appr. 50% lower) and poor stability as compared with the other one (MOR-T). Chemical etching the outer layer of as-made MOR-C crystals is proven to be an effective strategy to reduce surface barriers, enhance mass transport properties and improve the activity and stability of MOR catalyst. The carbonylation activity of etched MOR-C is indeed comparable to that of MOR-T. This work highlights the importance of controlling synthetic strategy and surface barriers on zeolite crystals for the design/development of highly efficient catalyst.

Related research results, entitled “Recognizing the Important Role of Surface Barriers in MOR Zeolite Catalyzed DME Carbonylation Reaction”were recently published onACS Catal. This work supported by Natural Science Foundation of China. (Text by Kaipeng Cao)

Recognizing the Important Role of Surface Barriers in MOR Zeolite Catalyzed DME Carbonylation Reaction. Cao, K.; Fan, D.; Gao, M.; Fan, B.; Chen, N.; Wang, L.; Tian, P.; Liu, Z., AcsCatal 2021, 1-7.