The essential mass transfer step in hierarchical/nano zeolite: surface diffusion

• 来源期刊: 国家科学评论（英文版）
• 年，卷（期）: 2020,（11）
• 所属期刊栏目: Special Topic:Hierarchically Porous Materials
• 页码范围: 1630-1632
• 页数: 3页
• 语种: 英文
• DOI: 10.1093/nsr/nwz208

摘要

An important topic in zeolite catalyst design is how to improve utilization efficiency of active sites in micropores by upgrading the effective diffusivity of reactants/products in zeolite crystal particles [1].Nano-and hierarchical structures have drawn lots of attention in zeolitic catalysis fields in recent years, because these two methods can obviously improve the catalysis efficiency by shorterring the configuration diffusion length [2].However, new problems were raised in the construction process of hierarchical or nano-zeolites.For instance, it was found that the hierarchical structure can change the intrinsic properties of surface acid sites in zeolite [3].Fan et al.reported that when the length scale of the zeolite approaches several nanometers, the diffusional time constants [4,5] and the apparent configuration diffusion lengths will be significantly increased than expected [6].Therefore, enhanced mass transport in hierarchical zeolite will be overpredicted if not considering the extent of sorbate-sorbent interaction.Lercher's group also found that the rate determining step of the transport processes depends on the particle size [7].