Present address:   Department of Chemical Engineering, Faculty of Engineering, Mahidol University, Nakorn Pathom, 73170 Thailand
Tel: +66-65-420-7864
E-mail: sakhon.rat@mahidol.edu

Brief Biography: Sakhon RATCHAHAT is a lecturer of Department of Chemical Engineering, Faculty of Engineering, Mahidol University, Thailand. He received his B.Sc. and M.Eng. in Chemical Technology and Chemical Engineering from Chulalongkorn University Thailand, and D. Eng. in Chemical Engineering at Tokyo Institute of Technology, Japan. He currently supervises two master students, and six bachelor students at Mahidol University. His research interests are heterogeneous catalysis for CO₂ utilization, biomass conversion technology, and advanced materials: Production of synthetic natural gas from carbon dioxide over structured catalytic system, Pyrolysis and gasification of biomass in molten salt reactor, and Development of synthesis method of carbon nanotube for battery application.

Power-To-Gas Technology (PtG): An Efficient Route for CO₂ Utilization

Sakhon RATCHAHAT, Masao SUDOH, Ryo WATANABE, and Choji FUKUHARA

Abstract

Controversial issues of CO₂ emissions on environment are greatly forcing the transformation from fossil fuels to clean energy. Solar and wind power as renewable energy would play an important role. Power-to-gas (PtG) technology has gained increased attention as a promising solution for storage of the electricity surplus by methane production from CO₂ greenhouse gas and renewable H₂ from water electrolysis. The methane can be more easily stored and transported than the electricity, while H₂ production by water electrolysis leads to the sustainable process. This promising process will play a substantial role in the future energy storage. It addresses not only electrical grid stability, but also reduction of CO₂ greenhouse gas. The purpose of this study is to develop a powerful CO₂ methanation process using a variety of structured Ni/CeO₂ catalysts. Various configurations of metallic honeycomb-type catalysts, which are plain, stacked, segment, and multi-stacked were constructed and tested under various reaction conditions; i.e. inlet temperature, feed flow rate and CO₂ partial pressure. Effects of the developed configurations including stack and gap distance were examined. The random-flow channels of stacked type and the gap distance of segment type could improve the catalytic activity, resulting in high CO₂ conversion. Under industrial-like high feed rate condition and pure feed gas component, a moderate hot spot over the multi-stacked catalyst was observed and reported for the first time. The moderate hot spot reboosted the conversion to a high level even at high feed flow rate condition of 3000 mL/min. As a result, high CO₂ conversion > 90%, high CH₄ selectivity > 99.5%, and high stability with dropped conversion < 0.6%, could be maintained over 76 h test at setting temperature of 300°C, flow rate of 3000 mL/min and feed CO₂/H₂ ratio of 0.12/0.88. The stability of the Ni/CeO₂ catalyst under the moderate hot spot condition was revealed by BET, SEM and XRD analyses.

Highlights:

• The powerful CO₂ methanation process was developed using a Ni/CeO₂ structured catalyst.

• The process was tested under high feed flow rate of 3000 mL/min with contact time of 235 ms.

• The moderate hot spot was observed over the multi-stacked type catalyst at high feed flow rate.

• The CO₂ conversion >90% and CH₄ selectivity >99.5% were obtained at 3000 mL/min and 300 °C.

• The slight decreased conversion <0.6% was found over 76 h test at 3000 mL/min and 300 °C.

Keywords: CO₂ methanation; Ni/CeO₂ Structured catalyst; Honeycomb

Related publication:

• Fukuhara, K. Hayakawa, Y. Suzuki, W. Kawasaki, R. Watanabe, A novel nickel-based structured catalyst for CO₂ methanation: a honeycomb-type Ni/CeO₂ catalyst to transform greenhouse gas into useful resources. Appl. Catal. A, 532 (2017), pp. 12-18

• Fukuhara C., Ratchahat S., Suzuki Y., Sudoh M., Watanabe R., Auto-methanation Performance of Structured Ni-type Catalyst for CO2 Transformation, Chemistry Letter, Vol.48, No.5, 2019, pp. 441-444.

• Fukuhara C., Ratchahat S., Kamiyama A., Sudoh M., Watanabe R., Auto-methanation of Carbon Dioxide: A Novel Route for Transforming CO2 over Ni-based Catalyst, Chemistry Letter, 2019, Vol.48, No.3, pp. 196-199.