from first principles PP-I-1

PP-III-35Reactivity of Ni and Co Hydrotalcite Type Catalysts in Dry ReformingReaction of MethaneHouaidji S. 1 , Bali F. 1 , Halliche D. 1 , Jalowiecki-Duhamel L. 21 Laboratoire de chimie du gaz naturel, faculté de chimie. USTHB, Algiers, Algeria2 Unité de catalyse et de chimie du solide. USTL, Lille, Francebalifer@gmail.comDry reforming of methane is more endothermic and produces a more adequate CO/H 2 ratiofor the synthesis of the valuable oxygenated chemicals than steam methane reforming, whichis the conventional route to transform natural gas into synthesis gas. In recent years, arenewed interest in the CO 2 reforming reaction has arisen from an environmental point ofview since this reaction is a CH 4 and CO 2 greenhouse gases consuming process.In this work we propose to examine the catalytic performances in this reaction of fivehydrotalcite type components, quoted Co-AlHT, Co-Mg-AlHT, Ni-AlHT, Ni-Mg-AlHT andNi-Co-Mg-AlHT. These solids were synthesized by coprecipitation method [1] andcharacterized by chemical analysis, BET, XRD, FT-IR, thermogravimetric analysis(ATG/ATD) and TPR. The study of the reaction was conducted in a differential dynamicsystem, it was done in a quartz fixed bed reactor at atmospheric pressure, the scale of reactiontemperatures varied from 400 to 800°C and the CH 4 /CO 2 ratio is equal to 1. Before eachcatalytic test, the sample was activated under hydrogen flow (DH 2 = 1.2L/h) at 600°C for12 hours. All materials are active from the first minutes of contact with the reactional mixture.The nickel based catalysts reach stationary state very fast (after 30 minutes), in comparison tothe cobalt based catalysts (100 minutes). The effect of reaction temperature showed that thecatalysts presented better catalytic performances at 650°C. At each examined temperature, thebinary catalysts are less active than their ternary homologous. At high temperature, theaddition of magnesium improves notably the CH 4 and CO 2 conversions of all systems,especially that of the NiMgAl-HT catalyst for which these values reach respectively 87.08%and 70.7%. The influence of this addition on the productivity of CO and H 2 is also noticeable.The best performances of the Ni-Mg-AlHT can be partly related to its texture and structureand to the fact that it is less acid than the cobalt compounds. The influence of the magnesiumwas justified by its dispersion effect [2], [3].References[1] Cavani, F. ,Trifiro, F., Vaccari, A., Catal.Today, 11, 1991, 173.[2] Unnikrishnan, R., Narayanan, S., Journal of molecular catal. A. Chemical, 144, 1999, 179.[3] Guo, J., Lou, H., Zhao, H., Chai, D. , Zheng, X. , Appl. Catal. A: Gen, 273, 2004, 82.187