450 / 2018-09-04 13:10:11

Steam reforming of tar model compounds over NiSepiolite catalysts Effect of La content on sinter and coke resistence

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Lanthanum modified Ni/SEP (sepiolite) catalysts were fabricated firstly by using co-precipitation method. The effect of La on physical and chemical properties of Ni/xLa-SEP catalysts (x = 0, 2, 4, 6, 8 and 10 wt%) was measured by employing ICP-OES, N2 adsorption-desorption, XRD, H2 pulse chemisorption, SEM/EDX-mapping, TEM, H2-TPR and XPS. The characterization results demonstrated the addition of La reduced the size of active metal and increased the active metal surface and metal-support interaction of Ni/SEP catalyst. Among them Ni/10La-SEP catalyst had the smallest active metal size (5 ± 0.5 nm) and the highest active metal surface area (12.3 m2/gcat.) and strongest metal-support interaction. In addition, the catalytic behaviors of Ni/xLa-SEP catalysts were evaluated during the steam reforming of phenol-ethanol (SRPE) under the following conditions: T = 600 oC, S/C = 1.7, and WHSV = 5.4 h-1. As expected Ni/10La-SEP revealed the highest carbon conversion (92.1%) and H2 yield (87.6%). Additionally, the selectivity to CO2 was increased with the addition of La, while those to CO and CH4 were reduced gradually, which indicative of La content enhanced the steam reforming of CH4 and WGS reactions, which could significantly increase the yield of H2. The XRD, TEM and TG-DTG technologies for selecting spent catalysts revealed that La successfully suppressed the sintering and coking of Ni/SEP catalyst. Among them, Ni/10La-SEP exhibited excellent long-term stability during SRPE.