(765e) Low Temperature Dry Reforming of Methane over Pt Promoted NiCe@SiO2 Multi–Yolk–Shell Nanotube Catalysts

Authors: 
Kim, S., University of South Carolina
Lauterbach, J., University of South Carolina
Sasmaz, E., University of California, Irvine
Dry reforming of methane (DRM) can be used to utilize greenhouse gases of CO2 and CH4, and convert biogas to value-added chemicals. DRM is typically performed at elevated reaction temperatures (> 750 ºC) due to the high energy needed to activate C–H and C–O bonds. This condition not only increases the operating costs but also causes catalyst sintering and carbon formation leading to catalyst deactivation. Therefore, low temperature (< 600 ºC) DRM is desired and has been researched on noble metal promoted (e.g., Pt, Ir, and Rh) Ni-based catalysts since they can exhibit high activity and stability against carbon deposition.

In this work, Pt promoted NiCe@SiO2 multi–yolk–shell nanotube catalysts have been investigated for low temperature (500 ºC) DRM. Our previous results confirmed that the NiCe@SiO2 multi–yolk–shell nanotube structure could exhibit a high turnover frequency and high resistance to carbon deposition compared to conventional NiCe/SiO2Imp synthesized by impregnation method in tri-reforming of methane at 750 ºC. These multi–yolk–shell nanotube structures have been further evaluated for DRM reaction at 500 ºC and the effect of Pt promotion is investigated. Our results indicated that NiCe@SiO2 without Pt promotion shows initial CO2 and CH4 conversions of 12.1% and 6.7%, respectively, which are lower than the CO2 (16.8%) and CH4 (11.6%) conversions on conventional NiCe/SiO2Imp. However, the activity of Pt-NiCe@SiO2 with 1 wt.% of Pt promotion increases CO2 and CH4 conversions to 17.3% and 11.7%, respectively. The Pt-NiCe@SiO2 shows stable activity, whereas the activity of Pt-NiCe/SiO2Imp decrease to 48.7% of its initial activity during 20 h of DRM reaction. On the other hand, Pt-NiCe@SiO2 with 0.25 wt.% of Pt promotion has higher resistance to carbon deposition than any other catalysts in our work. It is possible that the Pt–Ni alloy formation and multi–yolk–shell nanotube structure could enhance the DRM activity and lead to a lower carbon deposition. In the presentation, we will provide a detailed characterization of the samples using electron microscopy and x-ray spectroscopy, and elucidate the effect of Pt and Ni interaction on catalyst activity.