Synthesis of Na@nanoFAU Zeolite Catalyst and Catalysis for Production of Formic Acid with Na@nanoFAU

Abstract

Microporous aluminosilicate is one type of most important catalyst supports in catalysis reactions performed at high temperatures in gas phase and at a relatively low temperature in a liquid phase. There is significant limit of diffusion resulting from long diffusion path of molecules in a particle of aluminosilicate with a size of a few hundreds of nanometers and from the limited pore diameter of subnanometer when a catalytic reaction is performed in the micropores of aluminosilicate buried in liquid phase at a low temperature (< 200 °C). To avoid such diffusion limit, FAU at nanoscale (nanoFAU) was synthesized through growth of layered porous aluminosilicate in confined space between adjacent graphene oxide layers and a following removal of the graphene oxide through combustion at a high temperature. The as-synthesized nanoFAU exhibits a lateral dimension of tens of nanometers but a thickness of only 2–3 nm in terms of a single unit cell of zeolite. The Na+ cations anchored on Bronsted site in micropores of the as-synthesized nanoFAU exhibit (Na@nanoFAU) is active for synthesis of formic acid from CO and H2O in aqueous solution under the gas phase of 10 bar CO. The apparent activation barrier for synthesis of formic acid on this Na@nanoFAU is about 50.1 kJ/mol.