Search

This work investigates selective Ni locations over Ni/CeZrO x –Al 2 O 3 catalysts at different Ni loading contents and their influences on reaction pathways in ethanol steam reforming (ESR). Depending on the Ni loading contents, the added Ni selectively interacts with CeZrO x –Al 2 O 3 , resulting in the stepwise locations of Ni over CeZrO x –Al 2 O 3. This behavior induces a remarkable difference in hydrogen production and coke formation in ESR. The selective interaction between Ni and CeZrO x for 10-wt.% Ni generates more oxygen vacancies in the CeZrO x lattice. The Ni sites near the oxygen vacancies enhance reforming via steam activation, resulting in the highest hydrogen production rate of 1863.0 μmol/g cat ·min. In contrast, for 15 and 20-wt.% Ni, excessive Ni is additionally deposited on Al 2 O 3 after the saturation of Ni–CeZrO x interactions. These Ni sites on Al 2 O 3 accelerate coking from the ethylene produced on the acidic sites, resulting in a high coke amount of 19.1 mg c /g cat·h (20Ni/CZ-Al). [Display omitted] • Ni/CeZrO x –Al 2 O 3 for ethanol steam reforming are prepared at different Ni contents. • Depending on the Ni amounts, Ni selectively interacts with the CeZrO x –Al 2 O 3 support. • Stepwise Ni locations over CeZrO x –Al 2 O 3 remarkably affect the ESR reaction pathways. • Ni sites near the oxygen vacancies on CeZrO x enhance reforming via steam activation. • Ni sites on Al 2 O 3 accelerate coking from the ethylene produced on the acidic sites. [ABSTRACT FROM AUTHOR]