IADOR yields diverse shape-selective solid Lewis acid catalysts

Abstract

Lewis acid catalysts convert biomass compounds to green chemicals and fuels. Among these catalysts, stannosilicate zeolites display high thermal stability and reusability. However, only a few Sn-zeolites can be prepared using conventional synthesis methods, preventing us from developing shape-selective stannosilicate catalysts. Here, we propose a synthetic approach toward shape-selective Sn-zeolite catalysts, leveraging the Assembly, Disassembly, Organization, Reassembly (ADOR) strategy. By combining isomorphous Sn incorporation (i) into germanosilicate zeolites UOV, IWW, and IWR in the A step with structural modification in the DOR steps, we targeted new Sn-zeolite structures with either parallel or intersecting 12- and 8-ring pores predominantly containing Lewis acid centers with hydrolyzed Sn-O-Si bonds. The shape-selective performance of the designed Sn-zeolite catalysts was experimentally assessed and theoretically rationalized in transformations of citronellal into citronellol by Meerwein-Ponndorf-Verley reduction and into isopulegol isomers via intramolecular cyclization. Therefore, iADOR paves the way toward new zeolite catalysts with engineered Sn active sites for green chemistry.