抄録
CO_2 was added to the water in an Ar atmosphere and ultrasonic irradiation was carried out. CO and H_2 were produced from CO_2 and water, respectively. Detectable amount of H_2O_2 O_as also observed. H2O_2 was used for oxidation of the reactant in the solution. On the other hand, H_2 was possible to be consumed for deoxidizing from CO_2 as shown in equation (1). The reduction of CO_2, however, may occur directly in cavitation babbles as shown in equation (2). In order to examine the role of H_2 in the reaction system, sonochemical reactions were performed in H_2 or H_2-Ar atmosphere. CO_2+H_2→CO+H_2O・・・(1) 2CO_2→2CO+O_2・・・(2) CO and CH_4 were formed in a pure H_2 atmosphere under ultrasonication. The production of CH_4 was very interesting. The yield of CO increased with irradiation time, while the yield of CH_4 saturated after the initial production. This behavior was observed over 80% H_2-Ar atmosphere. Other management factors of ultrasonication were also examined. The yield of CO increased with the amount of addition of CO_2, although the yield of CH_4 seldom changed. The yield of CO was influenced with reaction temperature, but that of CH_4 was fixed. This fact showed the yield of CH_4 did not depend on temperature. Thus, it was seen that CH_4 yield in H_2 atmosphere was hardly influenced experimental conditions.
