<br/>Supported nickel catalysts are widely used in hydrocarbon reforming for hydrogen production. However, coke formation often leads to the rapid deactivation of Ni-based catalysts. In this work, we introduced Mo into Ni catalysts for isooctane and gasoline partial oxidation. The Ni-Mo catalyst showed high reforming activity and stability with isooctane conversion of 97% and H<sub>2</sub> yield of 73% over 24 hours. Under the same reforming condition, the monometallic Ni catalyst without Mo showed a rapid deactivation. TGA, XRD, Raman, and TEM analysis confirmed that the deactivation of monometallic Ni catalyst was significant due to the formation of graphitic carbon. Our results showed a bigger average Ni crystallite size for the monometallic Ni catalyst compared to that of Ni-Mo catalyst following the partial oxidation reaction, which indicates that the higher degree of sintering took place for the sample without Mo. XRD results confirmed that Mo incorporated into the Ni lattice (by partial substitution of Ni atoms by larger Mo atoms) forming a Ni-Mo solid solution. Beside the Ni-Mo solid solution sites, Raman results also suggested that presence of well dispersed Mo=O species over Ni surfaces can be a possible active sites that are related to the coke resistance and stability of Ni-Mo/YSZ catalyst sample. To examine the effects of the Mo addition in Ni/YSZ on preventing coking during the partial oxidation of isooctane reaction, CH cleavage and C-C coupling reactions over Ni and Ni-Mo catalysts were studied using DFT-based calculations. The results showed that Ni-Mo catalysts enhanced carbon-tolerance by increasing activation barriers of C-H cleavage and C-C coupling in the presence of Mo as compared with Ni/YSZ system. Ni-Mo catalyst was used as an internal micro-reforming layer on top of conventional Ni-YSZ anode supported single cells. The single cell without the catalyst layer showed an unstable voltage and the overall cell performance exhibited a rapid degradation rate of 49 mV/h after 6 h of operation. By applying the Ni-Mo/YSZ catalytic internal reforming layer, the single cell displayed significantly improved stability with a low degradation rate during the 15 h test. The improved performance stability denoted the positive function of the Ni-Mo/YSZ layer for efficiently reforming complex hydrocarbon fuels in the anode and suppressing carbon deposition.

Enhancing the performance of partial oxidation of gasoline over Ni catalysts with Mo addition for SOFCs application: Experimental and DFT studies

2019 Fall National Meeting

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