Synthesis and catalytic advantage of a hierarchical ordered macroporous KIT-6 silica
Sabina Siles-Quesada, Christopher M. A. Parlett, Alexander C. Lamb, Jinesh C. Manayil, Yang Liu, Jim Mensah, Hamidreza Arandiyan, Karen Wilson, Adam F. Lee
Abstract
Ordered mesoporous silicas are important technological materials in catalysis, sorption and separation science, however new architectures are desired to improve in-pore accessibility. Here we report the first synthesis of an ordered macroporous KIT-6, obtained by optimizing the ratios of Pluronic P123: sodium dodecyl sulfate cosurfactants, and a 400 nm polystyrene nanosphere macropore template. The macroporous KIT-6 possesses 370 nm macropores in a face-centered cubic arrangement, surrounded by a silica framework comprised of cubic Ia3¯d three-dimensional, intertwined 5 nm mesopore channels. Propylsulfonic acid (PrSO3H) functionalization affords a macroporous KIT-6 solid acid catalyst whose hierarchical pore network permits rapid diffusion and esterification of fatty acids, conferring a five-fold enhancement for palmitic acid esterification compared with a conventional mesoporous PrSO3H/KIT-6, and 33% rate enhancement vs. an ordered macroporous PrSO3H/SBA-15.