Hydrogen oxidation catalysed by X zeolite containing transition metal ions

Abstract

The catalytic activity of X zeolite for the oxidation of 1 % Halair in a flow system was augmented by the exchange of 20 % of the Na+ for transition metal ions. The kinetics were first order in Hz pressure, and from the temperature required to maintain kl = 2.0 x 1013 molecules g-' s-l Pa-' the

Development of catalyst system for selective combustion of hydrogen

“…It can be observed that the activities of MeZSM-5 were in the order: CuZSM-5>FeZSM-5>NiZSM-5. This order is in agreement with the orders in X-type and Y-type zeolites [21,23]. In those papers, they correlated the reaction activity with the content of reactive oxygen presented in Me-O-Me bridges.…”

“…On the other hand, two reduction steps of Cu 2+ to Cu + and Cu + to Cu ° in CuZSM-5 can be further demonstrated from the ratio (which was close to 1) of the first TPR band area to the second band area. Two similar reduction steps were also observed in X-type zeolite by Mahoney et al [21] and in Y-type zeolite by Jacobs et al [22].…”

“…According to the reduction temperatures of MeZSM-5 in this research, the order of reducibility is CuZSM-5>FeZSM-5>NiZSM-5. This sequence is the same as that for X-type zeolites containing transition metal ions ofCu, Fe and Ni [21]. Furthermore, the reducibility of ICu/Silicalite, which is close to CuZSM-5, is also higher than those of FeZSM-5 and NiZSM-5.…”

Catalytic oxidation of pyridine on the supported copper catalysts in the presence of excess oxygen

“…According to the literature [22][23][24], the reduction of unsupported or supported Fe 2 O 3 to metal Fe 0 occurs in three steps below 630 • C, with Fe 3 O 4 and FeO as the intermediates. The reduction of Fe 3+ species to metal Fe 0 in the charge compensation sites of zeolite requires the temperatures above 730 • C, but that of Fe 3+ to Fe 2+ is observed to occur at lower temperatures [25][26][27]. Therefore, the former two peaks could be assigned to the reduction of Fe 2 O 3 "clusters" to metal Fe 0 , with Fe 3 O 4 as intermediate species [28,29], and the third one corresponding to the reduction of Fe 3+ to Fe 2+ [30,31], where Fe 3+ species come from the oxidation of ion-exchanged Fe 2+ ions into zeolite by calcinations [32].…”

On the Role of Protonic Acid Sites in Cu Loaded FAU31 Zeolite as a Catalyst for the Catalytic Transformation of Furfural to Furan

“…In the case of Cu 5 H-Z, the obtained signal with maximum at 310 °C was greater than the signal registered for Cu 5 Na-Z with maximum localized at 320 °C. In all cases the obtained wide reduction peaks may be assigned to Cu 2+ →Cu 0 [ 51 , 52 , 53 , 54 , 55 ].…”