Heteropolyacids supported on hierarchically macro/mesoporous TiO 2 : efficient catalyst for deep oxidative desulfurization of fuel

The fabrication of polyoxometalates (POMs)-modified TiO 2 catalysts with connected pore structure has attracted great interests due to its prominent effect on mass transfer and catalytic oxidation activity. Here, we report a series of hierarchically macro/mesoporous (M/m) phosphotungstic acid (HPW)/TiO 2 composites, which are fabricated by colloidal crystal template method and applied as deep desulfurization catalyst in fuel oil. As-synthesized hierarchical HPW/TiO 2 composite is interconnected by ordered macroporous channel with disordered mesoporous embedded on pore walls. Moreover, Keggin-type HPW is homogeneously dispersed on the TiO 2 matrix. Hierarchical macro/mesoporous HPW/TiO 2 shows an excellent catalytic performance, the removal rate for dibenzothiophene in model fuel reaches 99% under the optimum conditions. This high performance of the three-dimensional ordered macropores (3DOM) HPW/TiO 2 can be attributed to its hierarchically porous which is highly beneficial for the mass transfer during the catalytic process. Moreover, the used catalyst could be regenerated by centrifugation and only slight decreasing of the catalytic activity after five cycles.