Effect of active sites distributions on temperature dependent–coke formation over Ni/CexZr1−xO2–Al2O3 catalysts for ethanol steam reforming: Coke precursor gasification
Mingyan Wang, Sang Yoon Kim, Azam Jamsaz, Nhiem Pham-Ngoc, Yong Men, Dong Hwi Jeong, Eun Woo Shin
Abstract
Understanding coke formation routes over Ni-based catalysts is essential in determining the catalytic performance in ethanol steam reforming. In this study, we focused on optimizing the active sites distribution via the metal-support interactions and understanding the coke precursor gasification in Ni/CexZr1-xO2–Al2O3 (CZA) catalysts for ethanol steam reforming. We found that the optimized active sites distribution could minimize coke formation by enabling efficient gasification of a coke precursor on Ni. In the 20Ni/40CZA catalyst, the crystalline CZ exhibited a strong interaction with Ni, maintaining a uniform distribution of highly dispersed Ni nanoparticles and creating abundant oxygen vacancies on CZ, even at 20 wt% of Ni loading. Consequently, the resistance to coking over 20Ni/40CZA was significantly enhanced due to the efficient delivery of active oxygen atoms from steam on the abundant oxygen vacancies to the coke precursor on the Ni surface, resulting in fast gasification of the coke precursor.