New insight into the synergistic promotion effect of phosphorus and molybdenum on the ceria-titanium catalysts for superior SCR performance

Abstract

The CePTiOx, CeMoTiOx and CePMoTiOx catalysts were synthesized via a solvothermal method and phosphorous or molybdenum was effectively doped into the cerium- titanium catalyst system. Although each component of the catalysts presented a high dispersion, which was clarified by crystal structure analysis, the performance of selective catalytic reduction (SCR) was dramatically individual. Three kinds of catalysts were systematically analyzed, which confirmed significant difference in microstructure and chemical characteristics. Notably, the CePMoTiOx catalyst exhibited a superior SCR reactivity, not only the NO conversion more than 80% ranging from 260 to 440 °C, but also displayed satisfactory H2O/SO2 durability and the airspeed resistance. It was verified that the trapping sites, oxygen vacancies, Brønsted acid sites and the specific surface areas were definitely promoted, pore channel was optimized, synergistic interaction among the components and reducibility were enhanced, which benefited from a suitable amount of phosphorus and molybdenum simultaneously doping into cerium-titanium catalyst. It was obvious that the advantages of phosphorus and molybdenum were combined for CePMoTiOx by a facile way. Meanwhile, it confirmed that the Mo species were apt to associate with SO2, which preserved high SCR activity during the SO2 resistance. These detailed studies could establish basic theory and provide some significant concepts for the construction of subsequent high performance catalysts.