Nickel Supported on AlCeO<sub>3</sub> as a Highly Selective and Stable Catalyst for Hydrogen Production via the Glycerol Steam Reforming Reaction

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

Format: Article
Diterbitkan: MDPI AG 2019-05-01

Deskripsi

In this study, a critical comparison between two low metal (Ni) loading catalysts is presented, namely Ni/Al<sub>2</sub>O<sub>3</sub> and Ni/AlCeO<sub>3</sub> for the glycerol steam reforming (GSR) reaction. The surface and bulk properties of the catalysts were evaluated using a plethora of techniques, such as N<sub>2</sub> adsorption/desorption, Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP&#8722;AES), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDX, Transmission Electron Microscopy (TEM), CO<sub>2</sub> and NH<sub>3</sub>&#8722; Temperature Programmed Desorption (TPD), and Temperature Programmed Reduction (H<sub>2</sub>&#8722;TPR). Carbon deposited on the catalyst&#8217;s surfaces was probed using Temperature Programmed Oxidation (TPO), SEM, and TEM. It is demonstrated that Ce-modification of Al<sub>2</sub>O<sub>3</sub> 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 H<sub>2</sub> and CO<sub>2</sub>, enhancement of WGS reaction, and a higher resistance to coke deposition. Allyl alcohol was found to be the main liquid product for the Ni/AlCeO<sub>3</sub> catalyst, the production of which ceases over 700 &#176;C. It is also highly significant that the Ni/AlCeO<sub>3</sub> catalyst demonstrated stable values for H<sub>2</sub> yield (2.9&#8722;2.3) and selectivity (89&#8722;81%), in addition to CO<sub>2</sub> (75&#8722;67%) and CO (23&#8722;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/Al<sub>2</sub>O<sub>3</sub> catalyst, whereas for the Ni/AlCeO<sub>3</sub> catalyst TPO studies showed the formation of more defective coke, the latter being more easily oxidized.