Synthesis and Characterization of Sn, Ge, and Zr Isomorphous Substituted MFI Nanosheets for Glucose Isomerization to Fructose.

Various metals including Sn, Ge, and Zr have been successfully incorporated into the MFI nanosheets via a one-pot synthesis. The as-synthesized zeolites exhibit high external surface area and mesopore volume without large metal oxides aggregated on zeolite surfaces. Interestingly, the successful introduction of heteroatoms in MFI nanosheets can be confirmed by shifted XRD peaks corresponding to the unit cell expansion due to the replacement of metals into the framework. In addition, the UV-Vis absorbance spectra reveal that at the suitable metal loading the incorporated tetrahedral coordination of metal species in the zeolite framework has been obtained. To illustrate the benefits of the prepared catalysts, the glucose isomerization to fructose was carried out in a water/dioxane system. Obviously, the SnMFI-NS samples, containing the high dispersion of metal isomorphous species demonstrate the outstanding catalytic behavior in term of fructose selectivity (>85 %).

Synthesis and Characterization of Sn, Ge, and Zr Isomorphous Substituted MFI Nanosheets for Glucose Isomerization to Fructose.

Invited for a cover feature this month is the research group of Asst. Prof. Dr. Chularat Wattanakit from School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Thailand. The cover picture shows the facile synthesis of Sn, Ge, and Zr isomorphously substituted MFI with hierarchical structures by a one-pot hydrothermal process. These designed materials illustrate the promising catalytic performance in glucose isomerization to fructose. More information can be found in the Full Paper by Chularat Wattanakit, and co-workers.

Tunable Acid-Base Bifunction of Hierarchical Aluminum-Rich Zeolites for the One-Pot Tandem Deacetalization-Henry Reaction.

The development of bifunctional catalysts is important in the synthesis of materials for multiple sequential reactions in one-pot tandem catalytic processes. In this context, a dealuminated acid-base bifunctional catalyst with a hierarchical aluminum-rich faujasite structure (zeolite Y) has been successfully prepared by the solid-state dealumination of NaX nanosheets with ammonium hexafluorosilicate (AHFS). The characteristic properties of catalysts were examined by means of XRD, SEM, TEM, N2 physisorption technique, ICP-OES, NH3 -TPD, CO2 -TPD, 27 Al NMR, 29 Si NMR, Al K-edge XANES, and Pyridine-FTIR. The materials exhibit a superior catalytic performance for one-pot tandem catalysis, for example, the synthesis of trans-ß-nitrostyrene with a yield close to 100 % in a tandem deacetalization-Henry reaction of benzaldehyde dimethyl acetal with nitromethane. The high catalytic performance is attributed to the facile transfer of bulky molecules between acid and basic sites in the presence of hierarchical structures.

Synthesis of hierarchical ZSM-12 nanolayers for levulinic acid esterification with ethanol to ethyl levulinate.

Hierarchical ZSM-12 nanolayers have been successfully synthesized via a one-pot hydrothermal process using dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPOAC) as a secondary organic structure-directing agent (OSDA). The as-synthesized ZSM-12 samples were characterized by means of XRD, SEM, TEM, N2 physisorption, and NH3-TPD. This clearly demonstrates that the TPOAC content and the crystallization time are crucial parameters for the formation of nanolayered structures. The presence of such a structure significantly improves the mesoporosity of ZSM-12 by generating interstitial mesopores between nanolayers, eventually resulting in enhancing external surface areas and mesopore volumes, and subsequently promoting the molecular diffusion inside a zeolite framework. To illustrate its advantages as a heterogeneous catalyst, hierarchical ZSM-12 nanolayers were applied in the catalytic application of an esterification of levulinic acid with ethanol to ethyl levulinate. Interestingly, hierarchical ZSM-12 nanolayers exhibit an improvement of catalytic activity in terms of levulinic acid conversion (78.5%) and ethyl levulinate selectivity (98.7%) compared with other frameworks of hierarchical zeolite nanosheets, such as ZSM-5 and FAU. The example reported herein demonstrates an efficient way to synthesize a unidimensional pore zeolite with hierarchical nanolayered structure via a dual template method and also opens up perspectives for the application of different hierarchical porous systems of zeolites in the bulky-molecule reactions such as in the case of levulinic acid esterification with ethanol.