Title : Evaluation of hydrotaicite-derived Ni catalysts for tri-reforming of methane process for CO2 conversion
The anthropogenic CO2 emission into the atmosphere is considered as a prime reason for global warming and climate change. One promising idea for the mitigation of CO2 emission is CO2 conversion and utilization (CCU). Tri-reforming of methane (TRM) process offers a unique way to chemically utilize CO2 to reform methane into synthesis gas. TRM process is a synergy between steam reforming of methane, dry reforming of methane and partial oxidation of methane processes. The major challenge of the TRM process is to develop a highly active and stable catalyst. In this effort, hydrotalcite-derived mixed metal oxides supported Ni catalysts are explored in an experimental study. The catalysts were synthesized by co-precipitation method. These were characterized by XRD, TPD, TPR, TGA, SEM, TEM, XPS and N2-physisorption to study their textural, physical, and chemical properties. Their performances were examined at 800oC and space velocity of 49200 mL/h.g in TRM reaction. Mg-Al mixed oxide supported Ni catalyst (Ni-Mg-Al) displayed strong resistance against deactivation due to coking and sintering but could not attain high activity. Also, memory effect property of hydrotalcites were incorporated to prepare different batches of Ni-Mg-Al catalysts. These catalysts showed high CH4 and CO2 conversions but lacked stability. Cu- and Zn-promoted Ni-Mg-Al catalysts demonstrated excellent activity and stability. Addition of Cu and Zn resulted in Ni-Cu and Ni-Zn alloy formation respectively which enhanced their catalytic performances significantly. Particularly, Ni-Zn-Mg-Al catalyst was the best among all the hydrotalcite-derived tested catalysts. Addition of Zn to Ni-Mg-Al modified the catalyst electronically. As per the XPS result, partial charge transfer from Zn to Ni made Ni election-rich and hence more capable of strong C-H bond scission. Moreover, geometric modification also occurred in Ni-Mg-Al catalyst upon Zn addition. Zn isolated Ni atom and avoided large Ni ensemble formation. It preferentially blocked the Ni edge sites, mainly responsible for carbon formation. Ni-Zn-Mg-Al attained high activity and was found remarkably stable in an 80-h experimental run.
Audience Take Away:
- The audience will learn about hydrotalcite-derived catalysts, which are relatively newer class of catalystsMethane reforming using steam is a conventional process to generate synthesis gas and hydrogen. But it produces a lot of CO2 as well. On the other hand, Tri-reforming of methane process can do the same job and chemically utilize the CO2. However, this process is less explored and studied. My presentation will give some insights on this new process.
- Methane reforming is an industrial process. The deactivation of reforming catalysts is a common problem. My experimental results may provide some strategies to deal with such challenges.
- My presentation discusses a promising alternative to curb CO2 emission and utilize CO2 as a carbon source.
- My experimental results of the presentation include chemical conversion of industrial flue gas from the electricity-power generation plants, a major source of CO2 emission.