Nickel Supported on AlCeO3 as a Highly Selective and Stable Catalyst for Hydrogen Production via the Glycerol Steam Reforming Reaction

Nikolaos D Charisiou,Mark A Baker,Steven J Hinder,Victor Sebastian,Maria A Goula,Georgios I Siakavelas,Binlin Dou,Kyriaki Polychronopoulou

doi:10.3390/catal9050411

Nikolaos D Charisiou, Mark A Baker + Show 6 more

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In this study, a critical comparison between two low metal (Ni) loading catalysts is presented, namely Ni/Al2O3 and Ni/AlCeO3 for the glycerol steam reforming (GSR) reaction. The surface and bulk properties of the catalysts were evaluated using a plethora of techniques, such as N2 adsorption/desorption, Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP–AES), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDX, Transmission Electron Microscopy (TEM), CO2 and NH3– Temperature Programmed Desorption (TPD), and Temperature Programmed Reduction (H2–TPR). Carbon deposited on the catalyst’s surfaces was probed using Temperature Programmed Oxidation (TPO), SEM, and TEM. It is demonstrated that Ce-modification of Al2O3 induces an increase of the surface basicity and Ni dispersion. These features lead to a higher conversion of glycerol to gaseous products (60% to 80%), particularly H2 and CO2, enhancement of WGS reaction, and a higher resistance to coke deposition. Allyl alcohol was found to be the main liquid product for the Ni/AlCeO3 catalyst, the production of which ceases over 700 °C. It is also highly significant that the Ni/AlCeO3 catalyst demonstrated stable values for H2 yield (2.9–2.3) and selectivity (89–81%), in addition to CO2 (75–67%) and CO (23–29%) selectivity during a (20 h) long time-on-stream study. Following the reaction, SEM/EDX and TEM analysis showed heavy coke deposition over the Ni/Al2O3 catalyst, whereas for the Ni/AlCeO3 catalyst TPO studies showed the formation of more defective coke, the latter being more easily oxidized.

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Biofuels are expected to play an important role in meeting the combined challenge of providing adequate energy supplies, while simultaneously combating the threat posed by climate change, with projections estimating that their use will grow from 1.3 million barrels of oil equivalent (BOE) in 2012 to 4.6 BOE in 2040 [1]
Different thermochemical processes may be used for the conversion of C3 H8 O3 into H2— e.g., aqueous phase reforming (APR), autothermal reforming (ATR) and super critical water reforming (SCWR)—the process that appears most promising is that of the steam reforming of glycerol (GSR) [6,7,8]
Both catalysts have a similar Ni metal loading, which was measured for the calcined samples at 7.14 and 7.69 wt % for Ni/Al2 O3 and Ni/AlCeO3, respectively

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Biofuels are expected to play an important role in meeting the combined challenge of providing adequate energy supplies, while simultaneously combating the threat posed by climate change, with projections estimating that their use will grow from 1.3 million barrels of oil equivalent (BOE) in 2012 to 4.6 BOE in 2040 [1]. Different thermochemical processes may be used for the conversion of C3 H8 O3 into H2— e.g., aqueous phase reforming (APR), autothermal reforming (ATR) and super critical water reforming (SCWR)—the process that appears most promising is that of the steam reforming of glycerol (GSR) [6,7,8]. This is because GSR has a high H2 production capacity per mol of C3 H8 O3 reformed (Equation (1)) and is a mature industrial technology unlikely to require major technical adjustments in switching feedstocks [9,10]. According to the thermodynamic studies undertaken, the GSR should be undertaken at high temperature (>630 ◦ C), high water to glycerol feed ratio (WGFR < 9:1, molar) and at atmospheric pressure [13,14]

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