Highly stable dealuminated zeolite support for the production of hydrogen by dry reforming of methane

Dealuminated FAU type Y and BEA zeolites were used as supports for the dry reforming of methane. Ni and Pt (1 or 0.5 wt%) were impregnated on these carriers to produce both monometallic and bimetallic catalysts. The catalysts were characterized before and after exposure to reaction conditions by XRD, X-ray fluorescence, N-2 adsorption, TGA, TPR, SEM, TEM and XPS analyses. The acidity of the fresh solids was also evaluated by TPD of ammonia and FT-IR measurements. The improvement of the accessibility with dealumination of the supports, as well as the high stability of the BEA zeolite support, generated high dispersion of the metals and improved catalytic activity of this solid. The FAU type Y supports show much more total acidity compared to that of BEA, which possess acid sites of medium strength. The results demonstrated that the bimetallic Ni-Pt/zeolite catalyst showed lower activity (e.g., NiPtY and NiPt beta activities were 1.70 and 1.90 g(metal)(-1) h(-1), respectively) than that of the monometallic Pt/zeolite catalyst (e.g., PtY and Pt beta activities were close to 2.0 and 3.20 g(metal)(-1) h(-1), respectively). NiY and Ni beta were practically inactive, which could be attributed to the formation of deactivating whisker-like carbon deposits (approximately 60 wt%) on the metal particles, combined with the high acidity of the support, which was measured by FT-IR analysis. In the case of Pt dispersed on BEA zeolite, it produced lower carbon deposition (16 wt%) and this coke was easily removed by CO2. Dealuminated BEA zeolite appeared to be a promising candidate for dry reforming of methane application due to its high stability and selectivity during 24 h of time on stream, in comparison with alumina (activity = 0.90 mol g(metal)(-1) h(-1)), active carbon (activity = 2.30 g(metal)(-1) h(-1)), and other zeolites. (C) 2008 Elsevier B.V. All rights reserved.