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Mass transfer of guest molecules has a significant impact on the applications of nanoporous crystalline materials and particularly shape‐selective catalysis over zeolites. Control of mass transfer to alter reaction over zeolites, however, remains an open challenge. Recent studies show that, in addition to intracrystalline diffusion, surface barriers represent another transport mechanism that may dominate the overall mass transport rate in zeolites. We demonstrate that the methanol‐to‐olefins (MTO) reaction can be modulated by regulating surface permeability in SAPO‐34 zeolites with improved chemical liquid deposition and acid etching. Our results explicitly show that the reduction of surface barriers can prolong catalyst lifetime and promote light olefins selectivity, which opens a potential avenue for improving reaction performance by controlling the mass transport of guest molecules in zeolite catalysis. [ABSTRACT FROM AUTHOR]

Mass transfer of guest molecules in nanoporous crystalline materials has gained attention in catalysis, separation, electrochemistry, and other fields. Two mechanisms, surface barriers and intracrystalline diffusion, dominate the mass transport process. Lack of methods to separately quantify these two mechanisms restricts further understanding and thus rational design and efficient application of nanoporous materials. Here we derive an approximate expression of uptake rate relying solely on surface permeability, offering an approach to directly quantify surface barriers and intracrystalline diffusion. By use of this approach, we study the diffusion in zeolitic materials, and find that the intracrystalline diffusivity is intrinsic to the topological structure of host materials at low molecular loading for the given guest molecules, while the surface permeability is sensitive to the non-ideality of a crystalline surface owing to the physical and chemical properties of the crystalline surface, host–guest interaction at the surface, and change of the environment. Mass transfer of guest molecules in nanoporous crystalline materials is dominated by surface barriers and intracrystalline diffusion. Here the authors derive an approximate expression of uptake rate relying solely on surface permeability, offering an approach to directly quantify both effects. [ABSTRACT FROM AUTHOR]