Catalytic Carbon Dioxide Reforming of Methane to Synthesis Gas by Sanjay P. Gandhi

Guided by: Dr. Sanjay S. Patel With Synopsis and CD 10EXTPHDE35

ABSTRACT:

The reforming of methane with carbon dioxide for the production of synthesis gas is appealing because it produces synthesis gas with higher purity and lower H2 to CO ratio than either partial oxidation or steam reforming. Lower H2 to CO ratio is a preferable feedstock for the Fischer-Tropsch synthesis of long-chain hydrocarbons. On the environmental perspective, methane reforming is enticing due to the reduction of carbon dioxide and methane emissions as both are viewed as harmful greenhouse gases. Commercially, nickel is used for methane steam reforming reactions due to its inherent availability and lower cost compared to noble metals. The same catalyst can be used for the dry reforming of the methane (DRM). However, nickel-alumina catalyst faces the severe problem of deactivation for the DRM due to significant coke formation. Thus, notable efforts have been concentrated on exploring new catalysts, which are resistant to carbon formation. Therefore environmental friendly DRM process was studied in the present study with main objective is to develop active and stable nickel-alumina catalyst with promoters which can be scaled-up. The catalysts were prepared by various methods like wet impregnation, co-precipitation, sol-gel, citrate etc. The nickel loading was varied in order to optimize its content. The promoters like ceria, zirconia and magnesia were incorporated in the nickel catalysts to enhance the activity and stability of DRM process. Dry reforming of methane was carried out in the solid-gas fixed bed catalytic reactor at atmospheric pressure, temperature 650-800 oC and 24000-48000 GHSV (gas hourly space velocity). Catalysts were subjected to various characterization techniques like XRD, BET, SEM, FTIR, AAS, TG-DTA etc to correlate the activity and properties of catalysts for subsequent improvement in the catalyst performance. Time on stream stability test was carried out to check and improve the stability of the catalysts. Ni/Al2O3 catalysts faced very high deactivation compared to ceria, zirconia and magnesia promoted Ni/Al2O3. The zirconia promoted catalyst exhibited high activity whereas ceria promoted exhibited high stability among all the catalysts studied. In order to improve activity and stability of catalyst both the promoters zirconia and ceria were incorporated in the Ni/Al2O3.