Boosting Fischer–Tropsch Synthesis via Tuning of N Dopants in TiO2@CN-Supported Ru Catalysts

Abstract

Nitrogen (N)-doped carbon materials as metal catalyst supports have attracted significant attention, but the effect of N dopants on catalytic performance remains unclear, especially for complex reaction processes such as Fischer–Tropsch synthesis (FTS). Herein, we engineered ruthenium (Ru) FTS catalysts supported on N-doped carbon overlayers on TiO2 nanoparticles. By regulating the carbonization temperatures, we successfully controlled the types and contents of N dopants to identify their impacts on metal–support interactions (MSI). Our findings revealed that N dopants establish a favorable surface environment for electron transfer from the support to the Ru species. Moreover, pyridinic N demonstrates the highest electron-donating ability, followed by pyrrolic N and graphitic N. In addition to realizing excellent catalytic stability, strengthening the interaction between Ru sites and N dopants increases the Ru0/Ruδ+ ratios to enlarge the active site numbers and surface electron density of Ru species to enhance the strength of adsorbed CO. Consequently, it improves the catalyst’s overall performance, encompassing intrinsic and apparent activities, as well as its ability for carbon chain growth. Accordingly, the as-synthesized Ru/TiO2@CN-700 catalyst with abundant pyridine N dopants exhibits a superhigh C5+ time yield of 219.4 molCO/(molRu·h) and C5+ selectivity of 85.5%.