Ruthenium nanoclusters dispersed on titania nanorods and nanoparticles as high-performance catalysts for aqueous-phase Fischer–Tropsch synthesis

Abstract

A series of robust nanocatalysts constructed from ruthenium nanoclusters dispersed on titania nanorods and nanoparticles (Ru/TiO₂) were synthesized by an amino acid-assisted solution reduction method and applied to aqueous-phase Fischer–Tropsch synthesis (AFTS). These catalysts showed excellent activity (33.8–48.0 mol_CO mol_Ru⁻¹ h⁻¹, 493 K) and heavy hydrocarbon selectivity (C₅₊: 59.5–71.3 wt%) toward the AFTS reaction. By coupling with X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and elemental analysis characterization, the effects of H₂ reduction pretreatment and metal–support interaction on the catalytic performance were investigated. H₂ reduction pretreatment was found to significantly increase the activity and C₅₊ selectivity of the catalysts for AFTS. Characterization results further indicated that the H₂ reduction results in an increased metallic Ru content and the removal of adsorbed amino acids during the preparation process, which produces more fresh Ru active sites. Metal–support interaction between Ru and TiO₂ was observed to have a great influence on the reduction degree of Ru nanoclusters. Strong metal–support interaction will hinder the reduction of Ru species to the metallic state, thereby reducing the Fischer–Tropsch synthesis activity and C₅₊ selectivity.