Abstract
PO43- guests anchored on metal vanadate hosts are as vital as SO32-/SO42- analogues in wide exploitation for expediting acidic/redox SCR cycles or ABS pyrolysis at low temperatures. This is due to their multiple roles as a provider of Brönsted acidic bonds (BA--H+) and as a dictator of the traits for labile/mobile oxygens (OL/OM) and oxygen vacancies (OV). However, the relationships of BA- (P5+-O2-)/BA--H+ (P5+-O2--H+)/OL/OV/OM feature for the host versus its mono-/bi-dentate PO43- binding mode (PO43-MONO/PO43-BI) has never been examined to-date. PO43- guests were thus grafted on MnV2O6 host at 300 °C and 400-500 °C to generate PO43-MONO-abundant P300 and PO43-BI-bountiful P400-P500, respectively. PO43-MONO species elevated OV hydrophobicity and OM mobility for P300, which were pivotal to enhance its H2O resistance and redox cycle efficiency over P400-P500, respectively. Conversely, PO43-BI species outperformed PO43-MONO counterparts in achieving higher OL nucleophilicity, which was central to reduce the SCR energy barriers and to promote acidic cycle efficiencies for P400-P500. Moreover, P500 had such hydrophobic BA- species that reveal the lowest energy barrier for pyrosulfate (S2O72- of dehydrated ABS) fragmentation among P300-500, thereby unveiling higher ABS resistance than P300-P400 and bi-dentate SO32-/SO42--ample MnV2O6 control with humid, poisonous gases being fed.
Published Version
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