The investigation of Ru/Mn/Cu–Al2O3 oxide catalysts for CO2/H2 methanation in natural gas

• New trimetallic catalysts of Ru/Mn/Cu supported Al2O3 with different ratios and calcination temperatures were studied in CO2/H2 methanation.
• Atomic ratios of Ru play an important role in preparing all those trimetallic catalysts.
• Ru/Mn/Cu–Al2O3 with ratio of 10:30:60 shows high catalytic activity in CO2 conversion and CH4 formation at lower reaction temperature 220 °C.
• Addition of Ru into Mn/Cu–Al2O3 catalyst showed more stable conversion of CO2 and high catalytic activity.

Malaysia sour natural gas that containing high contents of carbon dioxide (CO2), hydrogen sulphide (H2S) and other which can freeze out on exchanger surface, plugging lines and reduce plant efficiency. Therefore there is need for treat sour to sweet natural gas. In this study, the investigation influences of Ru over manganese/copper oxides catalysts were conducted and the catalysts were prepared by wet impregnation method. The Ru/Mn/Cu (RMC) catalysts were activated at different temperatures (100–1100 °C) for 5 h and at different ratios of Ru. Ru/Mn/Cu(10:30:60)/Al2O3 (RMC10) catalyst calcined at 1000 °C was assigned as the most potential catalyst, which gave 98.5% CO2 conversion and 70% methane (CH4) formation at reaction temperature of 220 °C. Moreover, the XRD diffractograms showed that the catalyst calcined at 1000 °C and 1100 °C are highly crystalline phase, while catalysts calcined at 100 °C, 400 °C and 700 °C showed highly amorphous in structure which dominated by Al2O3 support material. The FESEM analysis revealed that fresh and used catalysts were covered with homogeneously dispersed and small size surface particles in the range of 0.2–0.3 μm. Furthermore, EDX analysis revealed that there was 24% reduction of Ru in the used catalyst compared to fresh catalyst. Nitrogen adsorption analysis showed 9% reduction of surface area over the used catalyst.