(617hk) Optimized CeZrO2-Modification of the Metal-Foam-Coated Pd-Rh/Al2O3 Catalyst for CH4 Bi-Reforming Reaction

Kiseok Kim^1*, Partho Sarothi Roy², Jinwoo Song^3,4, Ji Man Kim³

^1*School of Chemical Engineering, Yeungnam University, Gyeongsan, 712-749, South Korea

²CE-CERT, University of California Riverside, CA 92507, USA

 ³Department of Chemistry, Sungkyunkwan University, Suwon, 440-746, South Korea

⁴R & D Center, Heesung Catalysts Corp., 91 Somanggongwon-ro, Siheung, 429-848, South Korea

^*Corresponding Author; Fax: +82-53-810-4631 E-mail:kimks@yu.ac.kr

Reforming of biogas by steam to syn gas is important for viable conversion of renewable energy resources because biogas consists primarily of the most simple and inexpensive hydrocarbon (CH₄) and the most stable carbon oxide (CO₂), both of which are major greenhouse gases. Steam-reforming of biogas is considered to be more beneficial than CO₂ (dry)-reforming of biogas, for steam is a reforming reagent that can alleviate catalyst fouling caused by carbon deposition which tends to be aggravated in dry reforming environment. To optimize the reaction condition and catalyst for steam-reforming of biogas will be more systematic if it is performed in the context of CH₄ bi-reforming, i. e., reforming of CH₄ in the presence of two reagents, carbon dioxide and steam. Some of our previous works on CH₄ bi-reforming have been performed for developing the process operating condition over the nano-scale, active and stable Pd-Rh catalyst supported on CeZrO2-modified Al₂O₃that is coated on a metal foam substrate designed to fit SOFC fuel processor application [1, 2].

In the present study, CeZrO₂-modification of Al₂O₃ support was optimized with respect to catalyst activity and stability as well as syn gas product yield and selectivity for CH₄ bi-reforming based on the reference operating condition obtained from Aspen Plus process simulation and previous experiments. CeZrO₂/Al₂O₃ weight ratio of the Pd-Rh catalyst support was varied as 0/100, 15/85, 25/75, 35/65, 50/50 and 75/25, and the catalyst performances were evaluated and compared in terms of CH₄ and CO₂ conversions, H₂/CO ratio of product syn gas, transient or accumulated coke deposition, and process thermal efficiency. CH₄ bi-reforming reaction runs were performed in a heat exchanger platform type reactor in the modes of transient activity screening and 200 h on-stream stability test. The fresh and used catalysts were characterized by BET surface area and porosity measurements, noble metal dispersion, and SEM as well as TEM analysis. Optimum relative abundance of CeZrO₂ within the alumina support was addressed for enhancing CH₄ bi-reforming performance of the Pd-Rh/Al₂O₃ catalyst.

References

1. P. S. Roy, M. S. Kang and K. Kim, Effects of Pd-Rh composition and CeZrO₂-modification of Al₂O₃ on performance of metal-foam-coated Pd-Rh/Al₂O₃ catalyst for steam reforming of model biogas, Catal. Lett. 144, 2021(2014).
2. P. S. Roy, A. S. K. Raju and K. Kim, Influence of S/C ratio and temperature on steam reforming of model biogas over a metal-foam-coated Pd-Rh/(CeZrO₂-Al₂O₃)catalyst, Fuel 139, 314(2015).