| Affiliation: | 1. State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum East China–Qingdao Campus, No. 66, West Changjiang Road, Huangdao District, P. R. China;2. Central Facility for Advanced Microscopy and Microanalysis, University of California, Riverside 900 University Avenue, Riverside, CA 92521 USA;3. “E. Djakov“Institute of Electronics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chausee Blvd., 1784 Sofia, Bulgaria;4. Laboratoire Catalyse et Spectrochimie, Normandie Univ, ENSICAEN, UNICAEN, CNRS, 6 Bd Maréchal Juin, 14000 Caen, France;5. State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum East China–Qingdao Campus, No. 66, West Changjiang Road, Huangdao District, P. R. China Laboratoire Catalyse et Spectrochimie, Normandie Univ, ENSICAEN, UNICAEN, CNRS, 6 Bd Maréchal Juin, 14000 Caen, France;6. Faculty of Chemistry and Pharmacy, University of Sofia, 1126 Sofia, Bulgaria |
| Abstract: | The mesopores formation in zeolite crystals has long been considered to occur through the stochastic hydrolysis and removal of framework atoms. Here, we investigate the NH4F etching of representative small, medium, and large pore zeolites and show that the zeolite dissolution behavior, therefore the mesopore formation probability, is dominated by zeolite architecture at both nano- and sub-nano scales. At the nano-scale, the hidden mosaics of zeolite structure predetermine the spatio-temporal dissolution of the framework, hence the size, shape, location, and orientation of the mesopores. At the sub-nano scale, the intrinsic micropore size and connectivity jointly determine the diffusivity of reactant and dissolved products. As a result, the dissolution propensity varies from removing small framework fragments to consuming nanodomains and up to full digestion of the outmost part of zeolite crystals. The new knowledge will lead to new understanding of zeolite dissolution behavior and new adapted strategies for tailoring hierarchical zeolites. |
