Title: Ni/Co-based nanocrystalline catalysts for hydrogen production from CO2 reforming of methane : Effect of toluene addition

Moises R. Cesario

Université du Littoral Cote d Opale, France


Moisés Cesario has a Ph.D. degree in physicochemical sciences from the University of Strasbourg (France) in co-supervision with the Federal University of Rio Grande do Norte (Brazil). He currently is a researcher at the University of Littoral Côte d’Opale (France). Passionate about research, innovation and new challenges, he has devoted the last decade of his academic career to the study of new technologies for obtaining "clean" energy using catalytic materials prepared by techniques of easy handling.  He is author of several articles published in journals and conferences proceedings, patent, book and chapter writing.


The research of new sources for “clean” energy, with a significant reduction of the greenhouses gases emission like carbon dioxide (CO2) and methane (CH4) are strongly encouraged. Hydrogen, a very attractive fuel for proceedings towards above mentioned goals, can be obtained by conversion of biogas. Biogas is a renewable energy source that can be produced by anaerobic decomposition of organic material. Biogas contains mainly methane (CH4: 50-75%), carbon dioxide (CO2: 25-50%) and small amounts of sulfur compounds (H2S: 0-3%), volatile organic compounds (VOCs, e.g. toluene) and water. 
The coupling of the biogas production with catalytic processes can be very attractive for its conversion into value-added chemical compounds. Thus, Syngas (CO + H2 mixture) or hydrogen can be obtained by catalytic reforming of biogas. In fact, the dry reforming of methane (DRM) using CO2 as a reforming agent has been investigated for this purpose. The syngas derived from the DRM reaction (Eq. 1) can be used to develop synthetic fuels by Fischer-Tropsch process. 
〖 CH〗_4 〖+ CO〗_2↔2CO+2H_2      〖∆H〗_298K=247 〖KJmol〗^(-1)                               
DRM reactions are highly endothermic and thermodynamically favored by high temperature and low pressures, which requires stable and active catalysts to induce high conversion. The catalysts deactivation by carbon deposition and presence of impurities in the gaseous mixture is a major drawback for commercial purposes in the chemical industry.
A crucial step before to implement such processes is to understand the effect of the powder synthesis method on the physicochemical properties of the catalytic materials, and its performance depends on the interaction of various factors, including particle size, dispersion of the active phase on the support, surface area, and reducibility of multicomponent phases. Therefore our aim is to study these different factors that control the reforming reactions and in particular those that may lead to catalysts deactivation by the presence of impurities such as toluene.
The cobalt and nickel catalysts supported on Ce0.9Gd0.1O1.95 (CGO) prepared by a one-step sol-gel method were herein studied for CO2 reforming of methane. The Ni0.2Co0.8-CGO material presented high CH4 and CO2 conversions at 650-800 °C and similar resistance towards carbon deposition compared to the catalysts with lower Co content. Ni-Co bimetallic materials were more active than copper based materials because of their high surface area which allows more dispersion of the metal phase, as a result, and accessibility to reagents. In addition, Ni0.2Co0.8-CGO catalyst has high reducibility and small crystallite size. The formation of the Ni-Co alloy can promote high reducibility and strong metal-support interactions. All these factors are important to avoid active phase sintering and carbon deposition, improving the catalytic properties. 
Preliminary tests of dry reforming of methane in the presence of 180, 550 and 1465 ppm of toluene have been performed using Ni0.2Co0.8-CGO nanocrystalline catalyst. The toluene addition of 180 ppm showed similar results compared those without toluene addition above 650 ° C. However, high toluene concentrations have significant influence on the decrease in CH4 and CO2 conversion and H2 and CO yield. These approaches will be deepened.