High Conversion to Aromatics via CO<sub>2</sub>-FT over a CO-Reduced Cu-Fe<sub>2</sub>O<sub>3</sub> Catalyst Integrated with HZSM-5
Guiyao Song, Minzhe Li, Peikun Yan, Muhammad Asif Nawaz, Dianhua Liu
Abstract
Direct hydrogenation of carbon dioxide (CO2) to value-added chemicals is a promising strategy to relive the greenhouse effect and replace the diminishing fossil fuels, but the huge CO2 inertness and C–C coupling barrier usually bring about numerous difficulties and count against catalytic performance. Here, a highly active and more economical composite catalyst composed of Cu-promoted Fe2O3 (nCu-Fe2O3) and HZSM-5 was developed for the selective conversion of CO2 to aromatics with 56.61% selectivity at a single pass. An extremely low CO selectivity of 3.51 at 57.30% CO2 conversion outperforming the previously reported conversion was achieved because of the beneficial synergism between Cu and Fe and the distinctive CO reduction prior to reaction which is favorable to the formation of oxygen vacancies for CO2 adsorption and iron carbide for Fischer–Tropsch synthesis (FTS). Additionally, through integrating HZSM-5 synthesized by the phase-transfer method (HZSM-5-pt) with nCu-Fe2O3, the distribution of benzene, toluene, and xylene in aromatics can be noteworthily increased to 54.18% and aromatics selectivity can be increased to 61.94%, without depression of catalyst activity. More significantly, a “H recycling” mechanism was found between oxide and zeolite, which plays a crucial role in “the disposal of H” within dehydrogenative aromatization, facilitating the formation of aromatics. In summary, nCu-Fe2O3/HZSM-5 demonstrates a prospective industrial application in aromatics production from CO2.