Abstract

Glycerol steam reforming (GSR) is a promising alternative to obtain renewable hydrogen and help the economics of the biodiesel industry. Nickel-based catalysts are typically used in reforming reactions. However, the choice of the catalyst greatly influences the process, so the development of bimetallic catalysts is a research topic of relevant interest. In this work, the effect of adding Cu, Co, and Cr to the formulation of Ni/SBA-15 catalysts for hydrogen production by GSR has been studied, looking for an enhancement of its catalytic performance. Bimetallic Ni-M/SBA-15 (M: Co, Cu, Cr) samples were prepared by incipient wetness co-impregnation to reach 15 wt % of Ni and 4 wt % of the second metal. Catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), N2-physisorption, X-ray powder diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA), and tested in GSR at 600 °C and atmospheric pressure. The addition of Cu, Co, and Cr to the Ni/SBA-15 catalyst helped to form smaller crystallites of the Ni phase, this effect being more pronounced in the case of the Ni-Cr/SBA-15 sample. This catalyst also showed a reduction profile shifted towards higher temperatures, indicating stronger metal-support interaction. As a consequence, the Ni-Cr/SBA-15 catalyst exhibited the best performance in GSR in terms of glycerol conversion and hydrogen production. Additionally, Ni-Cr/SBA-15 achieved a drastic reduction in coke formation compared to the Ni/SBA-15 material.

Highlights

  • Current energy and environmental policies are inextricably linked and focus on reducing CO2 emissions and ensuring energy supply [1]

  • Hydrogen is mainly produced from the thermochemical conversion of fossil fuels at high pressures and temperatures, by steam reforming of natural gas, which is associated with various environmental issues related to greenhouse gases

  • We showed that Ni is responsible for H2 production from ethanol steam reforming, CO generation and coke deposition could be decreased with the addition of certain loadings of Cu [19,20]

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Summary

Introduction

Current energy and environmental policies are inextricably linked and focus on reducing CO2 emissions and ensuring energy supply [1]. Catalysts for steam reforming processes are currently a research subject, mainly focused on the improvement of the catalytic activity, the selectivity to hydrogen, and the resistance to coke formation. This last issue is one of the main problems for catalyst deactivation, together with sintering of metal particles. In steam reforming of oxygenated hydrocarbons, the choice of the support is important in order to avoid dehydration reactions favored on acidic sites, which lead to increased carbon formation [29,30] In this sense, the use of silica-based materials, especially SBA-15, as a carrier in reforming catalysts, has been demonstrated to lead to good results [19]. These bimetallic materials are novel catalysts for glycerol steam reforming

Characterization of Catalysts
Small-angle
TEM images of of thethe calcined
Catalytic Test on Glycerol Steam Reformimg
Micrographs
Catalysts Preparation
Catalytic Test
Schematic

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