Methanol steam reforming over Cu/CeO2 catalysts: influence of zinc addition

Abstract

Recebido em 20/10/10; aceito em 17/3/11; publicado na web em 5/5/11Methanol steam reforming reaction was studied over Cu(5 wt.%)/CeO 2 with and without the presence of Zn. The Zn addition decreased the Cu +2 reducibility and increased the oxygen mobility of ceria. The main products were CO 2 and H 2 with small amount of CO. Selectivity to CO decreased with the Zn addition and it was lower at lower reaction temperatures and lower space velocities. At 230 ºC and W/F MeOH = 648 g min mol -1 selectivities to H 2 and to CO 2 were 100% on Zn/Cu/Ce. The catalytic results indicated that CO was mainly a secondary product formed from reverse water gas shift reaction.

Methanol dissociation on bimetallic surfaces: validity of the general Brønsted–Evans–Polanyi relationship for O–H bond cleavage

“…20 On the other hand, the decrease (especially at low temperature) of the selectivity of the Cu/CeO 2 catalyst toward CO species, which might be formed through the reverse water gas shi reaction, can be achieved by addition of Zn to the catalyst. 21 It seems that Zn addition decreases the Cu 2+ reducibility and increases the oxygen mobility of ceria, which promotes the water gas shi reaction with the concomitant reduction of CO. In relation to the mechanism of light alcohols reactions on surfaces, it is widely accepted that the rst step in the decomposition of methanol and ethanol on most transition metal surfaces is the breakage of the O-H bond.…”

Activity and stability of a CuO/CeO2 catalyst for methanol steam reforming

“…Some characteristics of CuO/CeO 2 fresh catalyst are shown in Table 1 and they were reported in a previous work [30]. Briefly, the copper chemical composition determined by XRF was 5.48 wt.% near to the nominal value and the specific surface area (S BET ¼ 39 m 2 g À1 ) was slightly lower than the bare support.…”

“…Liu et al [25] have reported an optimal composition of 26.9 wt.% Cu substantially lower than the optimum (80 wt.%) proposed by Oguchia et al [29]. We have studied supported catalysts with a lower loading (around 5 wt.%Cu) which have turned out to be very active in the methanol steam reforming [30].…”

“…Studies were performed in a conventional TPR equipment [30]. In a typical experiment, the samples were treated in He at 300 C for 30 min before the reduction.…”

“…The methanol steam reforming reaction was carried out in a glass tubular reactor operated at atmospheric pressure between 260 and 300 C [30]. The feed to the reactor was a gaseous mixture of methanol, water and nitrogen.…”