Methanation and photo-methanation of carbon dioxide at room temperature and atmospheric pressure

Abstract

The Sabatier reaction: CO₂+4H₂ → CH₄+2H₂O(g) ΔG°_298K = −27 kcal mol⁻¹ (1) is an important catalytic process of wide industrial and academic interest^1—3. It is applied to syngas conversion and the treatment of waste streams. Methane is one of the most important carbon resources of the world, serving as an energy vector as well as a feedstock for higher-value chemicals^4—6. Despite its favourable thermodynamics, the eight-electron reduction of CO₂ to CH₄ by hydrogen is difficult to achieve: high-energy intermediates impose large kinetic barriers, and the formation of side products is common. Intensive investigations during the past decade have therefore been aimed at improving the activity and selectivity of methanation catalysts ^1–3,8–11. Although significant progress has been made in this field, elevated temperatures (T>300 °C) and pressures (P> 1 atm) are still required for methane generation to proceed at significant rates and yields. Here we report the selective conversion of CO₂ to methane at room temperature and atmospheric pressure, using highly dispersed Ru/RuO_x loaded onto TiO₂ as a catalyst. The reaction rate is sharply enhanced through photo-excitation of the support material.