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Recognizing the Important Role of Surface Barriers in MOR Zeolite Catalyzed DME Carbonylation Reaction
journal contribution
posted on 2021-12-09, 14:08 authored by Kaipeng Cao, Dong Fan, Mingbin Gao, Benhan Fan, Nan Chen, Linying Wang, Peng Tian, Zhongmin LiuTransport
resistance in microporous zeolites has an important impact
on their applications in catalysis. Relative to the well-known intracrystalline
transport resistance, the significance of surface barriers on the
catalytic performance of zeolites has not been well recognized. Herein,
we report 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 distributions, and acidities
but quite different diffusion properties. The MOR-C sample with severe
transport limitations exhibits inferior apparent activity (∼50%
lower) and poor stability in comparison compared with the MOR-T sample.
Chemical etching of the outer layer of as-made MOR-C crystals has
been proven to be an effective strategy to reduce surface barriers,
enhance mass transport properties, and improve the activity and stability
of the MOR catalyst. The carbonylation activity of etched MOR-C is
indeed comparable to that of MOR-T. This work highlights the importance
of controlling the synthetic strategy and surface barriers on zeolite
crystals for the design/development of highly efficient catalysts.
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possess similar sihighly efficient catalystsdifferent organic structuredme carbonylation reactionreduce surface barrierssurface barrierscarbonylation activityzeolite crystalswork highlightssynthetic strategyouter layerosdas ).indeed comparableimportant roleimportant impacteffective strategydirecting agentsdiffusion lengthscomparison comparedchemical etchingcatalytic performanceal ratiosal distributions