Generating hydrogen-rich fuel-cell feeds from dimethyl ether (DME) using Cu/Zn supported on various solid-acid substrates Troy A. Semelsberger a,c, * , Kevin C. Ott b , Rodney L. Borup a , Howard L. Greene c a Materials Science and Technology Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA b Chemistry Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA c Department of Chemical Engineering, Case Western Reserve University, Cleveland, OH 44106-7217, USA Received 22 February 2006; received in revised form 26 April 2006; accepted 5 May 2006 Available online 15 June 2006 Abstract Several incipient wetness prepared catalysts containing copper and zinc were prepared in-house and reactor tested for the production of hydrogen from dimethyl ether steam reforming (DME-SR). The incorporation of copper and zinc onto a solid acid substrate (viz., zeolites ZSM-5 and Y with Si/Al = 2.5–140, g-Al 2 O 3 , and ZrO 2 ) combined the catalytic components for DME hydrolysis to methanol (MeOH) and methanol steam reforming (MeOH-SR) into a single catalyst. Catalyst characterizations included BET surface areas, metal loading, acidity measurements using isopropyl amine, thermogravimetric uptakes of DME, and X-ray diffraction studies. One co-ion exchange sample was tested and was found to be inactive toward DME-SR because of its inactivity toward methanol steam reforming. The most active catalyst was copper–zinc supported on g-Al 2 O 3 , reaching an equilibrium predicted hydrogen yield of 89% (steam-to-carbon ratio (S/C) = 1.5, space-time(t) = 1.0 s, T = 400 8C, and P abs = 0.78 atm). Of the zeolite-supported Cu/Zn catalysts, copper–zinc supported on zeolite ZSM-5 with a Si–Al ratio of 25 was observed to be the most active with a hydrogen yield of 55% (S/C = 1.5, t = 1.0 s, T = 275 8C, and P abs = 0.78 atm). # 2006 Elsevier B.V. All rights reserved. Keywords: Dimethyl ether; Hydrolysis; Zeolites; Methanol; Alumina; Zirconia; Acidity; ZSM-5; Y; Steam reforming; Hydrogen; Fuel cells 1. Introduction A promising alternative fuel is dimethyl ether (DME) because of its proposed uses as a diesel substitute (cetane #: 55– 60) and as a source of hydrogen-rich fuel-cell feeds [1]. DME as a fuel for solid-oxide fuel cells is also being researched [2,3].A review of the advantages of dimethyl ether over the other candidate fuels (e.g., Fischer–Tropsch fuels, biodiesel, metha- nol, ethanol, methane, etc.) as an alternative fuel are presented elsewhere [1,4,5]. Currently, dimethyl ether is produced commercially from a two-step process. The first step is methanol synthesis from syngas (typically from natural gas, although coal and biomass are viable sources of syngas); the second step is the dehydration of methanol to dimethyl ether over solid-acid catalysts (e.g., ZrO 2 [6], g-Al 2 O 3 [7–11], zeolites [8,10,12,13], and Cab-O-Sil [14]). Single-step processes for converting syngas directly to DME are being researched [15–27]. Because of the principle of microscopic reversibility, the solid-acid catalysts employed for methanol dehydration to DME can also be employed for the hydrolysis of dimethyl ether to methanol (the reverse of methanol dehydration), but the principle of microscopic reversibility makes no predictions on the absolute rates or the conditions needed for the reaction to proceed. For example, methanol dehydration over g-Al 2 O 3 occurs in the temperature range of 200–300 8C [8,9], while the hydrolysis of DME to methanol over g-Al 2 O 3 occurs in the temperature range of 300–400 8C [28] because of the potential inhibiting effects of adsorbed water on g-Al 2 O 3 [13]. The advantage of methanol dehydration to DME is the large equilibrium conversions of methanol (at 300 8C the equilibrium conversion of MeOH is 86%) [5,29]; the opposite is true for the reverse reaction where the equilibrium conversion of dimethyl ether is approximately 14% (at S/C = 0.5 and T = 300 8C) [29]. Our previous research indicated that the acid-catalyzed hydrolysis of dimethyl ether to methanol reaches equilibrium over ZSM-5 catalysts (Si/Al = 15, 25, www.elsevier.com/locate/apcata Applied Catalysis A: General 309 (2006) 210–223 * Corresponding author. Tel.: +1 505 665 4766; fax: +1 505 665 9507. E-mail address: troy@lanl.gov (T.A. Semelsberger). 0926-860X/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.apcata.2006.05.009