New insight into multiple hydrogen-bond networks of functional organosilicas system for collaborative transformation of CO2 under mild conditions

Abstract

It is challenging to integrate various active species into porous materials in an organized manner to realize efficient and synchronous CO2 adsorption and chemical conversion. Here multiple Lewis base and dual hydrogen bond donor (HBD) units were integrated into an organosilicon precursor, and novel triazine and hydrazo sites co-modified periodic mesoporous organosilicas (THPMOs) were prepared via a simple hydrothermal self-assembly method. The morphological structures of THPMOs with different contents of active sites were characterized. The THPMOs displayed high BET surface areas (699–876 m2/g) and favorable low-pressure CO2 adsorption capacities at 273 K. When combined with tetrabutylammonium iodide (TBAI), they promoted the model cycloaddition of CO2 and propylene oxide (PO) effectively. By regulating the molar ratios of organosilica precursors, the obtained THPMO-25 catalyzed this reaction and produced a 96 % propylene carbonate (PC) yield under mild conditions. Moreover, the THPMO-25 was applicable using various epoxides and also exhibited satisfactory structural stability during recycling. Combined with theoretical calculations, an insight into the reaction mechanism involving multiple hydrogen-bond interactions was provided. The robust and recyclable nanomaterials offer an attractive approach for CO2 adsorption and subsequent chemical synthesis of organic carbonate.