OP-II-3

PP-III-77thermodynamically enhanced (minimizing CO formation) and there is almost nosintering of the metallic function. However, hydrocarbon formation from MeOH andDME takes place above 300 °C on zeolite-based catalysts, which causes a drop inDME conversion and H 2 yield. An induction period is needed for hydrocarbonformation on HZSM-5 zeolite-based catalysts, and the duration of this periodsignificantly decreases with temperature and with the acid strength of the zeolite.Therefore, the catalyst prepared with a zeolite modified by alkaline treatment (whichmoderates its acidity) is more stable for hydrogen production in a long reaction.The catalysts with Cu/Zn ratio = 1/1 have higher activity for H 2 production due totheir higher metallic dispersion. Moreover, the addition of Al improves the physicalproperties of the catalyst leading to a better performance at low temperature, but italso enhances hydrocarbon formation above 300 °C. Consequently, the CZA/ATZ30bifunctional catalyst is suitable for obtaining high DME conversion (> 0.90) in DMESR below 300 °C. This temperature is sufficiently low for minimizing both by-productformation and catalyst deactivation by Cu sintering, which allows attaining high andstable H 2 selectivities (> 96%) and yields (> 90%).Table 1. DME conversion (X DME ) and H 2 yield (Y H2 ) in the DME SR on different bifunctional catalystsat 20 minutes of time-on-stream. Reaction conditions: 250-400 °C range, water/DME molar ratio = 3/1and space time of a) 0.595 g catalyst·h/g DME and b) 0.298 g catalyst·h/g DME .X DMET (°C) 275 300 325 400 275 300 325 400aG66/γ-Al 2 O 3 - 0.06 0.25 0.87 - 0.06 0.23 0.81G66/Z30 a 0.79 0.88 0.86 - 0.76 0.85 0.52 -G66/ATZ30 a 0.69 0.84 0.91 - 0.61 0.78 0.83 -G66/ATZ30 b 0.40 0.56 0.62 - 0.35 0.48 0.47 -CZ(2:1)/ATZ30 b 0.37 0.50 0.65 - 0.31 0.43 0.60 -CZ(1:1)/ATZ30 b 0.62 0.75 0.83 - 0.55 0.73 0.81 -CZA/ATZ30 b 0.66 0.79 0.86 - 0.58 0.74 0.76 -References[1]. Q. Zhang, F. Du, X. He, Z. T. Liu, Z. W. Liu, Y. Zhou, Catal. Today, 2009, 146, 50.[2]. D. Feng, Y. Zuo, D. Wang, J. Wang, Chin. J. Catal., 2009, 30, 223.[3]. T.A. Semelsberger, K.C. Ott, R.L. Borup, H.L. Greene, Appl. Catal. A, 2006, 09, 210-223.[4]. K. Cheekatamarla, C. M. Finnerty, J. Power Sources, 2006, 160, 490[5]. A. Alonso, B. Valle, A. Atutxa, A. Gayubo, A. Aguayo, Int. J. Chem. Reac. Eng., 2007, 5, ArticleA61.AcknowledgementsThis work was carried out with the financial support of the Ministry of Science andTechnology of the Spanish Government (Project PPQ2006-12006).Y H2585