Supported Ni catalyst made by electroless Ni-B plating for diesel autothermal reforming
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Supported Ni catalyst made by electroless Ni-B plating for diesel autothermal reforming Zetao Xia2, Liang Hong*1,2, Wei Wang2, Zhaolin Liu2 1
Department of Chemical and Biomolecular Engineering, National University of Singapore,
Singapore, 117576 2
Institute of Materials Research & Engineering, 3 Research Link, Singapore, 117602
ABSTRACT CexGd1-xO2-G (CGO)-supported Ni nano grains were prepared initially by electrolessly depositing Ni-B alloy nano particles onto an activated carbon (AC). The as-deposited Ni-B particles were then transferred from AC to CGO through the metallo-organic precursor approach. The resultant Ni/CGO catalysts displayed excellent catalytic activity and chemical stability against coking and sulfur poisoning in catalyzing autothermal reforming (ATR) of a surrogate diesel fuel, comprising dodecane, tetralin and a substituted thiophene. For comparison purpose, a Ni/CGO catalyst prepared by the conventional impregnation method was employed in the same ATR system. These two catalytic systems exhibited rather discrepant outcomes. It was found that the Ni(B)/CGO catalyst was capable of repressing selectivity of ethylene during the reforming process. In addition to this, CGO played a critical role in thermal cracking hydrocarbon chains and inhibiting sulfur poisoning. INTRODUCTION The solid oxide fuel cell (SOFCs) and proton exchange membrane fuel cell (PEMFC) have higher energy efficiency than internal combustion engine and can be fuelled by synthesis gas or hydrogen generated from reforming infrastructure fuel, such as diesel, using as an auxiliary power unit (APU) in automotive applications [1-3]. The supported-Ni catalyst system is most desired for the reforming of a liquid fuel due to its low cost and high activity. However, the Ni-based catalyst usually cannot inhibit carbon deposition, or coking, and sulfur poisoning. Such deactivation will become more severe with the increase in complexity of hydrocarbon molecules. The use of an oxygen conducting solid electrolyte in particular ceria as support for Ni metal clusters [4-7] is an effective solution to the deactivation because ceria offers not only strong stability to sintering but also surface oxygen vacancies. In addition, a part of CeO2 is reduced to Ce2O3 under reducing atmosphere. The Ce(III) species induces the sulfidation reaction and hence helps mitigate sulfur poisoning [8]. Such sacrificial role reduces sulfur poisoning at the Ni catalytic sites [9]. In the present study, a special chemical modification on the Ni atomic cluster was attempted. This method is illustrated in Figure 1 in which nanoparticles of Ni-B alloy were initially developed on an activated carbon (AC) by utilizing its high surface area and incinerable property. The AC-loaded Ni-B was uniformly dispersed in a metallo-organic gel of Ce3+-Gd3+ ions. When the mixture was subjected to pyrolysis and heat treatment, a CGO-supported NiO-B2O3, the precursor of the catalyst, was obtained. This two-step synthesis process, termed as nanoparticle transfer, benefited the distribu
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