Safe and efficient catalytic reaction for direct synthesis of CO from methylcyclohexane and CO2

Abstract

The reverse water gas shift (RWGS) reaction is one kind of the catalytic conversion of CO2 to reduce an enormous amount of CO2. However, the RWGS reaction has the safety hazards associated with the use of hydrogen and thermodynamic limitation. Therefore, this work proposes a new safe and efficient reaction route (CO2-MCH) to get CO from CO2 and methylcyclohexane (MCH). Thermodynamic calculations showed that the equilibrium CO2 conversion at 350 °C increased from 17.8 % of the RWGS reaction to 53.5 % of the CO2-MCH reaction. In the CO2-MCH reaction, the relationship of the catalytic performance with the metal dispersion, the Pt particle size and the acidity of Pt-based catalysts on the different supports was investigated, respectively. The results showed that the Pt/γ-Al2O3 catalyst with high dispersion of Pt particles, small particle size and medium acidity had good activity and selectivity. The relationships among Pt loading and Pt particle size on the Pt/γ-Al2O3 catalyst and the catalytic performance were evaluated. The Pt particle size gradually increased with the metal loading. A positive correlation was observed between Pt particle size and CO2 conversion; a volcano-type relationship was observed between CO selectivity and Pt particle size. In the CO2-MCH reaction at 350 °C, 0.1 MPa, LHSV = 6 h−1, the CO2 conversion was 24.7 %, the CO selectivity reached 95.2 %, and the Pt/γ-Al2O3 catalyst within 40 h showed good stability. Moreover, the mechanism of the CO2-MCH catalytic reaction over the Pt/γ-Al2O3 catalyst was speculated.