Stability of catalytic foam diesel-soot filters based on Cs_2O, MoO_3, and Cs_2SO_4 molten-salt catalysts

摘要

The durability of catalytic alumina and zirconia-toughened mullite ceramic foam diesel-soot filters was tested by exposing them to severe, artificial exhaust condutions. The catalytic performance, composition, and mechanical strength were constantly monitored. It was concluded that the mechanical strength of the catalytic filters may be reduced by an interaction of the catalyst with certain compounds of ceramic filters. In practice, it should be possible to minimize the effect by carefully controlling the composition of the ceramic filter. For instance, the presence of phosphorous in alumina-based filters support should be avoided. The stability of the current catalyst phases, based on Cs_2O, MoO_3, and Cs_2SO_4, is too low for application. Due to partial evaporation, emission of catalyst compounds into the environment is likely and when that happens significant deactivation of the catalytic phase is unavoidable. The catalyst was found to be soluble in water, which might be disastrous in the case of condensation occurring in the exhaust pipe.