Novel noble-metal-free ceramic filter with controlled pore structure for environmental cleaning

Abstract We previously reported the complete decomposition of volatile organic compounds (VOCs) on hydroxyapatite (HAp) powder and initially demonstrated the catalytic reaction mechanism, which makes HAp the most promising alternative to conventional noble-metal nanoparticle catalysts for the control of VOC emission and environmental cleaning. To further the practical application of the previous study, we fabricated porous HAp via facile gel-casting assisted direct forming with the aim of developing a new type of ceramic filter. The structural features of the pore, such as pore size and porosity, are selectively controlled by altering the amount of surfactant added and the forming time. The resultant porous HAp was successfully applied as a catalyst filter for VOC decomposition and exhibited performance that was comparable to that of HAp powder. In addition, the correlation between pore structure tailored gas permeability and catalytic performance of HAp filters was also investigated in depth. Instead of a noble-metal nanoparticle catalyst that must be carried by a porous ceramic filter, the superior catalytic activity achieved using the HAp filter itself presents a novel strategy for future VOC decomposition techniques.