Single-Pass Conversion of CO2/CH4 Mixtures over the Low-Loading Ru/γ-Al2O3 for Direct Biogas Upgrading into Renewable Natural Gas

Landfill gas is a source of CH4 emission, also rich in CO2 (up to 50 vol %). It can be upgraded to renewable natural gas (RNG) by separating CO2 and impurities. Alternatively, the CO2 contained in biogas can be converted into CH4 via the Sabatier reaction, using H-2 generated by water electrolysis. For industrial applications, it is beneficial to eliminate the energy-intensive CO2 separation step, converting biogas to RNG directly. In this work, a series of 0.02-1 wt % Ru/gamma-Al2O3 catalysts were prepared by wet impregnation and evaluated for a single-pass conversion of CO2-CH4 mixtures. Through the catalytic performance evaluation and characterization studies, the optimal Ru loading was identified as 0.1-0.5 wt %. For these catalysts, CO2 conversion of 80-87% was achieved at 450 degrees C and 90 000 mL/g.h, maintaining 95-99% selectivity to CH4 production. These catalysts also showed excellent stability over 100 h on stream, while maintaining 99-100% CH4 selectivity.

Automated summary

In this study, landfill gas was converted into renewable natural gas using catalysts. It was found that the optimal Ru loading for CO2 conversion was 0.1-0.5 wt%, achieving a conversion rate of 80-87%.