Mesoporous zirconosilicate doughnuts with high performance in liquid oxidative dehydrogenation of hydroquinone to quinone

Unusual partially crystalline ordered mesoporous zirconosilicate doughnuts with Si/Zr ratio as low as 1.5 were synthesized from the aqueous polymerisation of a single source molecular precursor Zr[OSi(Ot-BuO)(3)](4) without the use of any templating agent. A radial homogenous mesoporosity (4 nm) was observed inside these very regular sub-micrometric (600 nm) doughnuts. These structures were partially crystallized in hydrothermal conditions (100°C) into an analogous zircon (ZrSiO(4)) framework. The formation mechanism has been investigated. It is evidenced that chlorine anions Cl(-) concentration and pH value are essential to achieve the process, even if their role is still a matter of investigations. The obtained materials demonstrated even higher catalytic activity, selectivity and stability in the liquid oxidative dehydrogenation of hydroquinone to 1,4-benzoquinone compared to TS-1 zeolite catalysts and amorphous highly ordered mesoporous zirconosilicate materials.