Rh promoted and ZrO2/Al2O3 supported Ni/Co based catalysts: High activity for CO2 reforming, steam–CO2 reforming and oxy–CO2 reforming of CH4

Ni (2.5 wt%) and Co (2.5 wt%) supported over ZrO2/Al2O3 were prepared by following a hydrolytic co-precipitation method. The synthesized catalysts were further promoted by Rh incorporation (0.01–1.00 wt%) and tested for their catalytic performance for dry CO2 reforming, combined steam–CO2 reforming and oxy–CO2 reforming of methane for production of syngas. The catalysts were characterized by using N2 physical adsorption, XRD, H2–TPR, SEM, CO2–TPD, NH3–TPD, TEM and TGA. The results revealed that ZrO2 phase was in crystalline form in the catalysts along with amorphous Al oxides. Ni and Co were confirmed to be in their respective spinel phases that were reducible to metallic form at 800 °C under H2. Ni and Co were well dispersed with their nano-crystalline nature. The catalyst with 0.2% loading of Rh showed superior performance in the studied reactions for reforming of methane. This catalyst also showed good coke resistance ability for dry CO2 reforming reaction with 3.8 wt% of carbon formation during the reaction as compared to 11.6 wt% carbon formation over the catalyst without Rh. The catalyst performance was stable throughout the reaction time for CH4 conversions, irrespective of carbon formation with slight decline (∼1%) in CO2 conversion. For dry CO2 reforming reaction, this catalyst showed good conversion for both CH4 and CO2 (67.6% and 71.8% respectively) with a H2/CO ratio of 0.84, while for the Oxy-CO2 reforming reaction, the activity was superior with CH4 and CO2 conversions (73.7% and 83.8% respectively) and H2/CO ratio of 1.05.