Towards Stable Catalysts for Aqueous Phase Conversion of Ethylene Glycol for Renewable Hydrogen

• Published in: ChemSusChem 2013-09, Vol.6 (9), p.1717-1723
• Main Authors: Koichumanova, Kamila, Vikla, Anna Kaisa K., de Vlieger, Dennis J. M., Seshan, K., Mojet, Barbara L., Lefferts, Leon
• Format: Article
• Language: English
• Subjects: Aluminum Hydroxide - chemistry; Aluminum Oxide - chemistry; boehmite; Catalysis; Ethylene Glycol - chemistry; hydrogen; Hydrogen - chemistry; Platinum - chemistry; reforming; Renewable Energy; stability; sustainable chemistry; Water - chemistry
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201300445

Aqueous‐phase reforming of ethylene glycol over alumina‐supported Pt‐based catalysts is reported. Performance of the catalysts is investigated by conducting kinetics and in situ attenuated total reflectance (ATR)‐IR spectroscopic analysis. Pt/γ‐Al2O3 is unstable under APR conditions (270 °C, 90 bar) and undergoes phase transformation to boehmite [AlO(OH)]. This conversion of alumina is studied in situ by using ATR‐IR spectroscopy; transition into boehmite proceeds even at milder conditions (210 °C, 40 bar). Pt/γ‐Al2O3 deactivates irreversibly because the Pt surface area decreases owing to an increasing metal particle size and coverage with boehmite. However, Pt supported on boehmite itself shows stable activity. Surprisingly, the rate of formation of hydrogen per Pt surface atom is significantly higher on boehmite compared to an alumina‐supported catalyst. This observation seems correlated to both increased concentration of surface OH groups as well as to enhanced oxidation of Pt when comparing Pt/γ‐Al2O3 with Pt/AlO(OH). Transformation for high activity: Aqueous‐phase reforming (APR) of ethylene glycol over alumina‐supported Pt catalysts is reported. On heating and at high pressures, the alumina support transforms to AlO(OH) (boehmite). This phase transformation is studied in situ by using attenuated total reflectance IR spectroscopy. Pt/AlO(OH) shows excellent stability at APR conditions and allows efficient production of hydrogen. It is assumed that the high concentration of OH species on boehmite make it a promising support for catalysts.