Direct synthesis of hydrogen peroxide from hydrogen and oxygen over palladium-exchanged insoluble heteropolyacid catalysts

Palladium-exchanged insoluble heteropolyacid (Pd0.15CsxH2.7−xPW12O40) catalysts were prepared with a variation of cesium content (x = 2.0, 2.2, 2.5, and 2.7), and were applied to the direct synthesis of hydrogen peroxide from hydrogen and oxygen. Pd0.15CsxH2.7−xPW12O40 showed high catalytic performance even in the absence of H2SO4 additive, indicating that Pd0.15CsxH2.7−xPW12O40 acted as an efficient catalyst and served as an alternate acid source in the reaction. The catalytic performance of Pd0.15CsxH2.7−xPW12O40 increased with increasing surface acidity of the catalyst. Among the catalysts tested, Pd0.15Cs2.5H0.2PW12O40 catalyst with the largest surface acidity showed the highest yield for hydrogen peroxide.