Conversion of Green House CO<sub>2</sub> Gas into Useful Hydrocarbon Gasses by Photoreduction Method over TiO<sub>2</sub>/SiO<sub>2</sub> from Volcanic Ash

Abstract

In order to decrease CO2 level, converting the gas into hydrocarbon fuel gasses has been performed by using photoreduction method under TiO2/SiO2 photocatalysis. The silica (SiO2) for TiO2/SiO2 preparation was purified from volcanic ash, that mixed with TiO2 suspended in water. The photoreduction process of CO2 was carried out in a batch technique, by exposing CO2 and water vapor in the presence of TiO2/SiO2 photocatalyst with UV lamp for 24 h. The gasses produced from the photoreduction were determined by gas chromatography method. In the research, the effects of HCl and HNO3 as hydrogen ion supplier were also evaluated. The research results indicate that the photoreduction of CO2 with the water vapor over the photocatalyst of TiO2/SiO2-volcanic ash has successfully produced methane and ethylene as fuel gasses, while in the presence of TiO2 no ethylene was resulted. The methane produced by TiO2/SiO2 was observed to be larger than by TiO2 powder. The content of TiO2 in TiO2/SiO2 with low level strongly influenced the yield of the products. In contrast, the yield was independent on the TiO2 content in high level. The presence of the acids was found to increase the methane produced , and no ethylene was formed, but instead, methanol was resulted. The effect of HCl was higher than HNO3.