Steam Reduction of CO2 in a Photocatalytic Fluidized Bed Reactor

Unlike traditional catalysts that drive chemical reactions by thermal energy, photocatalysts can induce chemical reactions by light activation. It is well known that greenhouse gases, such as CO2, are the primary causes of global warming. From an environmental point of view, it is interesting to transform CO2 into hydrocarbons, such as CH4. Since this transformation has high energy duty, a photocatalytic process can be an effective way. There are few examples in literature concerning the use of photocatalytic fluidized bed photoreactor for the reduction of CO2 into CH4. The aim of this work is to investigate the performances of a high efficiency two-dimensional fluidized bed catalytic photoreactor with Cu/TiO2, Ru/TiO2 and Pd/TiO2. CH4 was the main product with very few amounts of CO. No deactivation phenomena were observed. Pd/TiO2 photocatalysts showed the best performances. At Pd load of 1 wt. %, CH4 photoproduction was 64 mu mol g(-1) h(-1), against 15 mu mol g(-1) h(-1) achieved with bare TiO2. The photoreactivity reached with Pd/TiO2 is significantly higher than that reported in the current literature on gas-solid photocatalytic systems for the photoreduction of CO2.