Title : Development of NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane
Abstract:
Liquid organic chemical hydride is a promising candidate for hydrogen storage and its easy transport.
Dehydrogenation of methylcyclohexane (MCH) to toluene (TOL) has been considered as one of the feasible cycles for
hydrogen carrier, but selective dehydrogenation of MCH has only been reported using the noble Pt-based catalysts. The
aim of this study is to develop non-noble, cost-effective metal catalysts that can show excellent catalytic performance,
mainly maintaining high TOL selectivity achievable by Pt based catalysts. Mono-metallic Ni based catalyst is a wellknown
dehydrogenation catalyst, but the major drawback with Ni is its hydrogenolysis activity to cleave C-C bonds,
which leads to inferior selectivity towards dehydrogenation of MCH to TOL. This study elucidate addition the second
metal to Ni based catalyst to improve the TOL selectivity. Herein, ubiquitous bi-metallic nanoparticles catalysts were
investigated including (Ni–M, M: Ag, Zn, Sn or In) based catalysts. Among the catalysts investigated, the highest TOL
selectivity (> 99% at low conversion) was achieved effectively using the supported NiZn catalyst under flow of excess
H2. In this work, a combined study of experimental and computational approaches was conducted to determine the main
role of Zn over Ni based catalyst in promoting the selectivity towards dehydrogenation of MCH to TOL. A kinetic study
along with density functional theory (DFT) calculation using mono- and bimetallic Ni based catalysts were conducted
to elucidate reaction mechanism and site requirement for MCH dehydrogenation reaction. The impact of different
reaction conditions (feed compositions, temperature, space velocity and stability) and catalyst properties were
evaluated.
