Methane catalytic combustion over Pd/Al2O3 in presence of sulphur dioxide: development of a regeneration procedure

Abstract

Five different procedures (treatments with hydrogen, nitrogen, wet and dry air, and under vacuum) were tested for the regeneration of a partially deactivated alumina-supported Pd catalyst, used for the catalytic incineration of methane in presence of SO 2 . The efficiency of these processes was evaluated considering the temperatures at which both, the catalysts deactivation, and the regeneration processes, took place. As general trend, hydrogen treatment is the best regeneration procedure, followed by treatment with wet air, whereas high deactivation temperatures lead to less efficient regeneration. The efficiency of the regeneration was observed to increase as regeneration temperature increases. These trends are discussed according to the results obtained in the characterisation of deactivated catalyst samples using TPR, TPO and TPD.

Sulphur poisoning of palladium catalysts used for methane combustion: Effect of the support

“…Oxygen releases were not observed for all the catalysts studied. This result, also observed for commercial Pd/Al 2 O 3 catalyst [11], suggests the formation of surface sulphites, rather than sulphates, whose decomposition produce a simultaneous release of O 2 and SO 2 .…”

“…Many authors attribute this effect to the strong adsorption of SO 2 and SO 3 (generated by catalytic oxidation of the SO 2 , H 2 S or organic sulphur compounds) on the active phase surface [9,10]. In many cases even the formation of palladium sulphates and/or sulphites is reported [11][12][13]. The catalyst support also seems to play a key role on the sulphur poisoning.…”

Studies on the influence of H 2 S and SO 2 on the activity of a PdO/Al 2 O 3 catalyst for removal of oxygen by total oxidation of (bio-)methane at very low O 2 :CH 4 ratios

“…Ordonez et al [28], a complete in-situ recovery of the catalytic activity under reaction conditions is possible, as the original activity of the fresh catalyst is reached. The experimental findings lead to the conclusion that the active compound is regenerated to PdO and that Al 2 (SO 4 ) 3 neither physically blocks active sites nor significantly narrows pores at conditions applied in this work, which would lead to a mass transfer limitation of the methane oxidation.…”

Kinetics of the sulfur oxidation on palladium: A combined in situ x-ray photoelectron spectroscopy and density-functional study

“…The adsorption of these sulfur traces on the catalyst surface can lead to a substantial decrease of its reactivity. 10,11,[13][14][15][16][17][18][19][20][21] First endeavors to understand the effects of sulfur on the electronic structure, the adsorption capacity, and reactivity of palladium have been undertaken, 22 a) K. Gotterbarm and N. Luckas contributed equally to this work. b) Authors to whom correspondence should be addressed.…”