Direct synthesis of hydrogen peroxide from hydrogen and oxygen over palladium catalyst supported on SO3H-functionalized MCF silica: Effect of calcination temperature of mesostructured cellular foam silica

Abstract

Palladium catalysts supported on SO 3 H-functionalized MCF silica (Pd/SO 3 H-MCF-T (T=450, 550, 650, 750, 850, and 950)) were prepared with a variation of calcination temperature (T, o C) of MCF silica. They were then applied to the direct synthesis of hydrogen peroxide from hydrogen and oxygen. Conversion of hydrogen, selectivity for hydrogen peroxide, and yield for hydrogen peroxide showed volcano-shaped curves with respect to calcination temperature of MCF silica. Yield for hydrogen peroxide increased with increasing acid density of Pd/SO 3 H-MCF-T catalysts. Thus, acid density of Pd/SO 3 H-MCF-T catalysts played an important role in determining the catalytic performance in the direct synthesis of hydrogen peroxide. Pd/SO 3 H-MCF-T catalysts efficiently served as an acid source and as an active metal catalyst in the direct synthesis of hydrogen peroxide.

Heterogeneous Pd catalysts supported on silica matrices

“…235 More recent studies were focused on similar catalysts deposited on 3-sulfonatopropyl modied mesoporous silica supports (MCM-41, MCM-48, MCF, MSU-1 and SBA-15). 236,237 In this case, the catalytic results were shown to be inuenced by the amount of acidic groups at the support surface and by calcination temperature used during the preparation of the MCF support.…”

Geometry Modification of Helical Gear for Reduction of Static Transmission Error

“…Smith studied about reducing gear transmission error according to contact ratio changes. Park [3] and Perret-Liaudet [4] classified transmission error into static transmission error (STE) and dynamic transmission error (DTE). Many traditional scientists studied method to reduce transmission error in gear system.…”

Direct Synthesis of Hydrogen Peroxide from Hydrogen and Oxygen over Mesoporous Silica-Shell-Coated, Palladium-Nanocrystal-Grafted SiO2 Nanobeads

“…Currently, over 3.0 million metric tonnes of hydrogen peroxide is being produced annually by the anthraquinone oxidation process. However, an alternative process is required, because the anthraquinone process operates using lots of hazardous organic chemicals and is unsuitable for the small/medium sized production of hydrogen peroxide . The direct synthesis of hydrogen peroxide from hydrogen and oxygen (reaction route I, Scheme ) is received as the only alternative process which satisfies the requirements.…”

“…However, an alternative process is required, because the anthraquinone process operates using lots of hazardous organic chemicals and is unsuitable for the small/medium sized production of hydrogen peroxide. 7 The direct synthesis of hydrogen peroxide from hydrogen and oxygen (reaction route I, Scheme 1) is received as the only alternative process which satisfies the requirements. The direct synthesis of hydrogen peroxide has virtues as a green chemistry process: It is a singlestep reaction which can occur under ambient temperature and pressure without a requirement and emission of environmentally hazardous chemicals.…”

“…8 However, a more fundamental reason is an insufficient selectivity (or yield) of hydrogen peroxide due to the occurrence of side reactions producing water. All of the (three) side reactions (routes II, III, and IV, Scheme 1) are spontaneous with negative Gibbs energies of reaction, 7,9 which thereby compete with the hydrogen peroxide-production reaction, making negative influences on obtaining a high selectivity of hydrogen peroxide. Such low activities have been improved continuously over decades, owing to the advancement of catalyst technology.…”