Two-Stage Catalytic Conversion of Carbon Dioxide Into Aromatics Via Methane

Area of Science:

• Catalysis
• Chemical Engineering
• Sustainable Chemistry

Background:

• The transition to a circular economy necessitates alternative feedstocks for chemical production, moving beyond fossil fuels.
• Carbon dioxide (CO2) presents a potential C1 feedstock for synthesizing valuable chemicals.
• Aromatics, such as benzene, are crucial chemical building blocks for fuels and materials.

Purpose of the Study:

• To investigate a two-stage catalytic route for producing benzene from CO2.
• To identify optimal conditions for a sequential CO2 methanation and methane dehydroaromatization (MDA) process.
• To assess the stability and efficiency of the integrated catalytic system.

Main Methods:

• Thermodynamic calculations to predict reaction feasibility and optimal conditions.
• Experimental investigation of a two-stage reaction system using Ni/TiO2 and Mo/ZSM-5 catalysts.
• Analysis of reaction products and catalyst stability under varying feed compositions.

Main Results:

• Successful conversion of CO2 to benzene via sequential methanation and MDA reactions.
• Identification of "goldilocks conditions" where unreacted CO2 and H2 from the first stage enhance benzene production in the second stage.
• Sustained benzene production for over 72 hours by suppressing catalyst deactivation through controlled addition of CO2 and H2.
• Achieved an overall benzene yield of 5% from CO2.

Conclusions:

• The combined CO2 methanation and MDA process offers a viable pathway for catalytically converting CO2 into benzene.
• Careful control of reactant concentrations, particularly H2, is critical for process stability and preventing catalyst coking.
• This approach demonstrates potential for sustainable production of aromatic compounds from waste CO2.