AuCu/TiO2 catalysts prepared using electron beam irradiation for the preferential oxidation of carbono monoxide in hydrogen-rich mixtures

Abstract

The major part of the world production of hydrogen is originated from a combination of methane steam reforming and water gas shift reaction resulting in a n H 2 rich mixture known as reformate gas, which contains about 1% vol (10, 000 p pm) of carbon monoxide (CO). The preferential oxidation reaction of CO in H 2 rich mixtures (CO PROX) has been considered a very promising process for H 2 purification, reducing CO for values below 50 ppm allowing its use in Proton Exchange Membrane Fuel Cells (PEMFC). Au nanopart icles supported on TiO 2 (Au/TiO 2 ) catalysts have been shown good activity and selectivity for CO PROX reaction in the temperature range between 20 ºC and 80 ºC; however, the catalytic activity strongly depend s on the preparation method. Also, the addition of Cu to the Au/TiO 2 catalyst could increase the activity and selectivity for CO PROX reaction. In this work, AuCu/TiO 2 catalysts with composition 0.5%Au0. 5%Cu/TiO 2 were prepared in a single step using electron beam irradiation, where the Au 3+ and Cu 2+ ion s were dissolved in water/2 propanol solution , the TiO 2 support was dispersed and the obtained mixture was irradiated under stirring at room temperature using different dose rates ( 8 64 kGy s 1 ) and doses 144 576 kGy The catalysts were characterized by energy dispersive X ray analysis (EDX), X ray diffraction (XRD), transmissi on electron microscopy (TEM), temperature programmed reduction (TPR) and tested for CO PROX reaction In the studied conditions, it was observed that the increase of t he dose rate and the total dose contributed to a decrease in the mean nanoparticle sizes. The best result was obtained with a catalyst prepared with a dose rate of 64 kGy s 1 and a dose of 576 kGy showed a CO conversion of 45% and a CO 2 selectivity of 30% at 150 o C.