دانلود رایگان مقاله سنتز فیشر تروپش دی اکسید کربن

Abstract

Paradigm of climate change mitigation technologies is shifting from carbon capture and storage (CCS) to carbon capture and utilization (CCU). Here we propose a new path to CCU – direct CO2 conversion to liquid transportation fuels by reacting with renewable hydrogen produced by solar water splitting. The highly promising and CO2-neutral CCU system is possible by our discovery of a new catalyst that produces liquid hydrocarbon (C5+) selectivity of ∼65% and greatly suppressed CH4 formation to 2–3%, which represents an unprecedented selectivity pattern for direct catalytic CO2 hydrogenation and is very similar to that of conventional CO-based Fischer-Tropsch (FT) synthesis. The catalyst was prepared by reduction of delafossite-CuFeO2 and in-situ carburization to Hägg carbide (χ-Fe5C2), the active phase for heavy hydrocarbon formation. The reference catalysts derived from bare Fe2O3, CuO-Fe2O3 mixture, and spinel CuFe2O4 are much less active and produce mainly light hydrocarbons, highlighting the critical role of delafossite-CuFeO2 as the catalyst precursor. The new catalyst breaks through the limitation of CO2-based FT synthesis and will open the avenue for new opportunity for carbon recycling into valuable liquid fuels at the similar conditions to industrially practiced CO-FT synthesis.

5. Conclusions

Delafossite-CuFeO2 becomes a precursor to Cu Fe catalysts that produce higher liquid hydrocarbons with a selectivity of ∼65%, an olefin-to-paraffin ratio of ∼7.3, and minimal methane selectivity of 2–3%. This represents a typical product distribution obtained from FT synthesis from CO over efficient iron-based catalysts. This represents the first demonstration that liquid fuels and olefins of high value and large market could be obtained from CO2, the most troublesome greenhouse gas. The unique role of delafossite-CuFeO2 as the catalyst precursor is attributed to the swift reduction and selective carburization to form the Hägg iron carbide (-Fe5C2), which is the active catalytic phase for the formation of higher hydrocarbons in CO2 hydrogenation. Other precursors like Cu2O-Fe2O3 and CuFe2O4 are not effective in the formation of the active phase although they contain copper. We believe the new catalyst breaks through the limitation of CO2-based FT synthesis and will open the avenue for new opportunity for recycling CO2 into valuable fuels and chemicals.