Effect of Na, K, Ca and P-impurities on diesel oxidation catalysts (DOCs)

A deactivation mechanism study of phosphorus-poisoned diesel oxidation catalysts: model and supplier catalysts

“…Similar phenomena were also observed by other groups. 12,18,30 Correlating the BET results to the ICP results (Table 1) reveals that the catalysts with a larger amount of phosphorus results in a lower surface area. The loss of surface area of Supplier_P93 (ca.…”

“…For example, three-way catalysts (TWC) were successfully introduced in stoichiometric gasoline engines in the late 1980s, 10 resulting in significant reduction of the emission of CO, HCs, and NO x from gasoline vehicles. For diesel engines, the diesel oxidation catalysts (DOCs), 11,12 or lean NO x trap (LNT), 13,14 is capable of oxidizing CO and HCs, where LNT is typically applied in lightduty vehicles and is also used for NO x removal in mixed lean conditions. Urea selective catalytic reduction (SCR) is commonly used for removing NO x from diesel engines.…”

“…15 Despite the significant catalytic oxidation performance of DOCs, various poisoning species, e.g., alkali or alkaline earth metals (Zn, Ca, and Mg), sulfur, and phosphorus (P), are normally detected on the surface of monoliths wash coated with DOCs after long-distance driving. 12,16,17 Of these, phosphorus derived from engine oil is one of the most difficult contaminations that can permanently deactivate DOCs due to the difficulty to regenerate upon thermal treatment. 18,19 The use of alternative fuels, e.g., biodiesel, has been gaining increasing attention in order to meet stringent CO 2 emission requirements.…”

“…Several groups have conducted phosphorus-poisoning investigations over catalytic components, such as the DOC, and selective catalytic reduction (SCR) catalysts. 12,[21][22][23][24] Kröger et al 25 have found that phosphorus poisoning results in a decrease in the specific surface area and pore volume in DOCs and an increase in the average pore size of the catalysts. Toops and coworkers 18 have studied the deactivation mechanism of Pt/CeO 2 /Al 2 O 3 upon phosphorus poisoning, where phosphorus primarily in the form of aluminum phosphate was found to accumulate mainly at the front of the DOC.…”

“…Toops and coworkers 18 have studied the deactivation mechanism of Pt/CeO 2 /Al 2 O 3 upon phosphorus poisoning, where phosphorus primarily in the form of aluminum phosphate was found to accumulate mainly at the front of the DOC. Anguita et al 12 have also conducted a study of the effect of impurities (Na, K, Ca and P) from biofuel on the performance of a DOC catalyst (i.e., Pt, Pd/CeZrO 2 /La-Al 2 O 3 ). They found that CO and C 3 H 6 oxidation were enhanced, while NO to NO 2 conversion decreased in the presence of P species.…”