A parametric study on catalyst development for glycerol DRY reforming

Abstract

Glycerol reforming to hydrogen and synthesis gas has drawn much attention re cently due to increased glycerol production related with the global biodiesel demand. Among several reforming techniques, dry reforming is more promising since it involves consumption of a major greenhouse gas, CO2. Regarding the lack of information es pecially about catalysis in the literature, this study aims to develop active and stable catalysts to be used in glycerol dry reforming systems. Furthermore, effects of opera tional parameters, namely reaction temperature, carbon dioxide-to-glycerol (CO2/G) molar feed ratio and residence time, on reactant conversions and production distri butions were investigated. Rh and Co based single oxide (ZrO2 and CeO2) catalysts were tested under glycerol dry reforming conditions for 72 hours to comprehend the stability of the catalysts. Catalyst characterization methods (TEM-EDX, in-situ FTIR and ex-situ Raman spectroscopic measurements) together with longevity studies sug gested that Rh and Co based single oxide catalysts were not stable due to severe coke formation and sintering. Based on the knowledge obtained from the experiments and the literature, Rh, Ni and Co based catalysts were prepared with ZrO2-TiO2 (ZT) and Al2O3-ZrO2-TiO2 (AZT). 1 wt.% Rh/AZT and Rh/ZT together with 5 wt.% Ni/AZT and Co/AZT were tested under varying temperatures between 600 and 750 ◦C, CO2/G ratios between 1 and 4 and residence time between 0.5 and 3.75 mgcat min NmL-1. At studied conditions, the highest activity was found over Rh/AZT catalyst followed by Ni/AZT, Rh/ZT and Co/AZT in decreasing order. Increasing temperature and de creasing CO2/G ratio had positive effect on reactant conversion as well as desired product yields, namely H2 and CO. Stability tests and BET, TEM-EDX and in-situ FTIR spectroscopic analyses were revealed the good stability of Rh/AZT and Ni/AZT.