(231f) Hydrogen Production Via Oxidative Steam Reforming Of Methanol Over Cu/ce/al Oxide Catalysts

Introduction The realistic alternative to the conventional combustion engine of automobile carriers can be a fuel cell, which does not emit the toxic pollutants at tail pipe. The hydrogen required for the functioning of fuel cell can either be stored in pressurized tank or generated on-board using liquid hydrogen carrier such as methanol that offers several advantages [1,2]. The use of pressurize hydrogen has some technical and economical problem. Therefore present study has been carried out to produce hydrogen from methanol with high yield and low CO selectivity by developing appropriate catalyst and optimizing process parameters. The oxidative steam reforming of methanol [Reaction (1)], combination of steam reforming (SRM) and partial oxidation (POM), was carried out over different CuCrAl and CuCeAl catalysts. CH3OH + (1-2a)H2O + aO2 ↔ CO2 + (3-2a)H2, DH0 = (49.5 - 241.8*a), 0 Results and Discussion Chemical composition, surface area and activities of different catalysts are listed in Table 1. It can be seen that an excessive CuO loading onto catalysts resulted in a decrease in surface area. XRD patterns (Fig. 1) revealed that on the reduction of catalyst copper oxide reduced to the copper while cerium oxide and aluminum oxide remained in oxide form only. The TPR profiles indicated Cu-Ce-Al-oxide catalysts could be reduced at lower temperature compared to Cu-Cr-Al-oxide catalysts. The methanol conversion for different catalysts as a function of temperature is shown in Fig. 2 at contact time 17 kgcat s mol-1. Among Cu-Cr-Al-oxide catalysts maximum methanol conversion 86% was obtained with the 2CuCrAl (Cu/Cr/Al: 30/10/60) catalyst at 260 oC. Catalysts modified by CeO2 showed significant enhancement not only in terms of methanol conversion but also in terms of H2 production rate and minimization of CO formation. The methanol conversion and H2 rate increased up to 0.3 O/M, after reaching to the limiting value it decreased with further increase in the O/M ratio.

In the present study the 2CuCeAl catalyst exhibited consistent performance for which methanol conversion decreased by the magnitude of 3% over the period of 60 h run-time.

Conclusion The catalyst 2CuCeAl (Cu/Ce/Al:30/10/60) has been found effective for the production of hydrogen by oxidative steam reforming of methanol in terms of maximization of hydrogen production with minimum CO formation for PEM fuel cell applications. Optimum operating conditions, W/F=19 kgcat s mol-1, T=280 oC, O/M molar ratio=0.25-0.3 and S/M molar ratio=1.4, could be suggested to obtain the high methanol conversion and hydrogen production rate. Incorporation of ceria increased the durability of catalysts by providing thermal stability and coke gasification to minimize the sintering and coking respectively.

References 1. Breen, J.P., and Ross, J.R.H., Catal. Today 51, 521 (1999). 2. Agarwal, V., Patel, S., and Pant, K.K., Appl. Catal. A 279, 155 (2005). 3. Patel, S., and Pant, K.K., Chem. Engg. Sci. under review (2006).