Renewable hydrogen production by ethylene glycol steam reforming over Al_2O_3 supported Ni-Pt bimetallic nano-catalysts

摘要

The steam reforming of ethylene glycol, a simple model compound for biomass-derived liquids, is considered to be an environmentally green process for producing renewable hydrogen. Both Pt and Ni species are known for their catalytic activity under steam reforming reaction conditions. In this investigation, alumina supported Ni-Pt bimetallic catalysts (X wt% Ni-Y wt% Pt/Al2O3 named XNi-YPt) were employed for steam reforming of ethylene glycol. The prepared catalysts were characterized by XRD, BET, H-2-TPR, H-2-Chemisorption, and TEM. It was observed that Ni/Pt ratio strongly affected the redox behavior, BET surface area, and particle size of the samples that in turn affected their catalytic performance. The optimum catalyst sample was 3.75Ni-1.25 Pt which resulted in the highest ethylene glycol conversion (60%), highest H-2 selectivity (45%) and yield (27%), and a minimum of 20 h of stability due to the lowest amount of coke formed the catalyst surface. The overall order of the catalytic performance of the samples was as follows: 3.75Ni-1.25 Pt 2.5Ni-2.5 Pt 1.25Ni-3.75 Pt 0Ni-5Pt 5Ni-0Pt. A kinetic model for the steam reforming of ethylene glycol in a packed bed reactor containing the 3.75Ni-1.25 Pt catalyst was employed indicating a good agreement between experimental and predicted H-2 selectivity and yield. Intrinsic reaction rate data in the absence of the heat and mass transfer limitations were obtained in parametric studies (Temperature range of 823-893 K, ethylene glycol mole fraction range of 0.056-0.116 and bed density of 18-26 kg m(-3)). Higher temperature and bed density and lower ethylene glycol mole fraction enhanced the reactivity. The maximum ethylene glycol conversion (70%), H-2 yield (36.5%) and H-2 selectivity (52%) was observed for conditions of 893 K, bed density of 24 kg m(-3) and ethylene glycol mole fraction of 0.056. (C) 2018 Elsevier Ltd. All rights reserved.