Enhanced Isoparaffin Selectivity in CO₂ Hydrogenation by Combining Na-Promoted Fe₃O₄ and Pt/WO₃-ZrO₂ Catalysts

Abstract

Catalytic CO 2 hydrogenation facilitated by Fe 3 O 4 produces long-chain hydrocarbons and light olefins through the combination of the reverse water–gas shift reaction and Fischer–Tropsch synthesis in a single reactor. Complementing Fe 3 O 4 -based catalysts, zeolites can be incorporated to modulate the product distribution of long-chain hydrocarbons in a dual-bed configuration. However, zeolites with strong acid sites induce the cracking of extended hydrocarbon chains, thereby impeding the production of hydrocarbons exceeding 12 carbon atoms. This paper introduces a novel Pt/WO 3 -ZrO 2 (PtWZ) catalyst to produce liquid isoparaffins, aligning with the requirements of sustainable fuel characteristics. The precise adjustment of Pt and W contents in PtWZ enhances the hydrogenation and isomerization of linear olefins, amplifying the yield of isoparaffins. A dual-bed reactor integrating PtWZ (0.01 wt % Pt) with Na-promoted Fe 3 O 4 catalyst achieved a CO 2 conversion rate of 40% and a CO selectivity of 10%, while maximizing isomerization performance, attaining 42% isoparaffinic selectivity within liquid hydrocarbons at operating conditions of 340 °C, 20 bar, weight hourly space velocity = 4500 mL·h –1 ·g cat –1 . In contrast to zeolite catalysts prone to coke deposition during the reaction, the PtWZ catalyst exhibited remarkable stability, sustained activity without discernible deterioration, and negligible coke deposition, even after continuous operation for more than 100 h. This outcome delineates an optimized catalyst technology for the sustainable production of fuel from CO 2, offering a viable alternative to the prevailing dependence on fossil fuels.