Selective photocatalytic reduction of nitric oxide by carbon monoxide over silica-supported molybdenum oxide catalysts

The photocatalytic reduction of NO by CO over a MoO3/SiO2 catalyst (2.5 wt% of Mo), which proceeds under UV irradiation at room temperature, is reported for the first time. N-2 and CO2 are found to be the major reaction products, and the selectivity of the photoreduction is close to 100%. After completion of photoconversion of a NO-CO mixture and brief evacuation at room temperature, a new portion of the NO-CO mixture admitted to the catalyst can be converted with the same rate as during the first irradiation. It is shown that MoO3/SiO2 is an inefficient catalyst for the thermal NO reduction by CO, since heating of a NO-CO mixture at 400 and 500 degrees C yields only small amounts of N-2 and CO2. A reaction mechanism for the photocatalytic NO reduction by CO over MoO3/SiO2 is proposed and discussed. (C) 1999 Academic Press.