Positive Effect of Water Vapor on CO Oxidation at Low Temperature over Pd/CeO2–TiO2 Catalyst

Abstract

CO oxidation at low temperature over Pd/CeO 2 -TiO 2 catalyst was carried out in the feed containing different contents of water vapor (H 2 O). A positive effect of H 2 O was observed on the catalytic performance of Pd/CeO 2 -TiO 2 in CO oxidation at low temperature. The extent of this effect depends on the content of H 2 O in the feed; with a H 2 O content being 2.5 vol%, the catalyst Pd/ CeO 2 -TiO 2 exhibits the highest stability (longest life time for CO oxidation at 80°C). The results of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed reaction (TPReaction) reaction illustrated that H 2 O in the feed supplies sufficient OH groups in the presence of O 2 , which can react with adsorbed CO on Pd species to produce CO 2 . Moreover, H 2 O may also enhance the adsorption of CO and suppress the formation of some carbonate species.

A comparative study of the catalytic oxidation of HCHO and CO over Mn0.75Co2.25O4 catalyst: The effect of moisture

“…In general, low-temperature catalytic oxidation is known to be greatly influenced by moisture in the reactant gas, the presence of which is unavoidable in most applications.Interestingly, water can play different rolesin the same reaction over different kinds of catalysts. As observed for low temperature CO oxidation, a moderate amount of water on the surface of precious metals such as Au, Pt, Ru, and Pd can promote the reaction [3][4][5][6][7][8][9][10][11]. On the other hand, it can act as a poison on the surface of metal oxides, such as Co 3 O 4 , CuO,…”

Catalytic removal of carbon monoxide over carbon supported palladium catalyst

“…CO oxidation studies by El-Shall shown that 5% Pd supported on CeO 2 , ZrO 2 have a CO to CO 2 conversion of 100% at 108 and 140 • C whereas 5% Pd/SiO 2 and Au/CeO 2 show 95 and 100% conversion at 200 • C. A mixture of 5% micronsized Pd and 95% micronsized CeO 2 reaches a maximum conversion of only 90% at temperature near 300 • C. Pd-Au/TiO 2 shows 1% and 100% conversion at 150 and 250 • C respectively [8]. Liang et al [33] have shown 100% CO conversion at 80 and 100 • C in wet and dry conditions respectively on Pd/CeO 2 -TiO 2 . Snytnikov et al [35] reported only 55% CO conversion at 155 • C in excess hydrogen on Pd/carbon.…”

“…CO outlet reached to 15 ppm at 400 and 360 min at 80 and 90% RH respectively. The faster breakthrough of CO at high humidity is due to the blockage of active sites of Pd/C catalyst by H 2 O adsorption [31,33,34]. Fig.…”

CO and H2 oxidation over Pt/BaSnO3 catalysts

“…This reaction seems to be one of the best known and extensively studied. So far many different hypotheses have been suggested to explain the mechanism of H 2 oxidation over platinum catalyst [42][43][44]. It is not well established whether the formation of water molecules over platinum catalyst corresponds to Langmuir-Hinshelwood (LH) or Eley-Rideal (ER) mechanism.…”