Highly Efficient ZIF-67-Derived PtCo Alloy–CN Interface for Low-Temperature Aqueous-Phase Fischer–Tropsch Synthesis

Abstract

Designing new materials for selective Fischer–Tropsch synthesis (FTS) is an elegant way to enhance local feedstock utilization like biomass and waste. In this approach, we have designed a thermally and chemically stable bimetallic PtCo/NC hybrid nanocomposite catalyst derived from a zeolitic imidazolate framework (ZIF-67, which contains cobalt as a metal center) through carbonization for low-temperature (413–473 K) aqueous-phase Fischer–Tropsch synthesis (AFTS). The selectivity of the desired range of hydrocarbons is adjusted using a highly dispersed PtCo bimetallic alloy, which facilitates extraordinary reduction of a metal oxide to active species by the synergic effect under the AFTS reaction conditions. The ZIF-derived catalyst tested in this study exhibited the highest activity to date for very low temperatures (433 K) in aqueous-phase Fischer–Tropsch synthesis with CO conversion rates between 0.61 and 1.20 molCO·molCo–1·h–1. Insights of the remarkable catalyst activity were examined by in situ X-ray photoelectron spectroscopy (XPS) studies corroborated by density functional theory (DFT) calculation. The bimetallic Co3Pt (111) surface was found to be highly active for the C–C coupling reaction between surface-adsorbed C and CO, forming a CCO intermediate with a very low activation barrier (Ea = 0.37 eV), in comparison to the C–C coupling activation barrier obtained over the Co (111) surface (Ea = 0.87 eV). This unique approach and observations create a new path for developing next-generation advanced catalyst systems and processes for selective low-temperature FTS.