Centrality of phosphate binding modes on metal vanadate in exploiting low-temperature NO_X reduction and pyrosulfate dissociation pathways

PO₄^3- guests anchored on metal vanadate hosts are as vital as SO₃^2-/SO₄^2- 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 (O_L/O_M) and oxygen vacancies (O_V). However, the relationships of BA^- (P⁵⁺-O^2-)/BA^--H⁺ (P⁵⁺-O^2--H⁺)/O_L/O_V/O_M feature for the host versus its mono-/bi-dentate PO₄^3- binding mode (PO₄^3‐_MONO/PO₄^3‐_BI) has never been examined to-date. PO₄^3- guests were thus grafted on MnV₂O₆ host at 300 °C and 400–500 °C to generate PO₄^3‐_MONO-abundant P300 and PO₄^3‐_BI-bountiful P400-P500, respectively. PO₄^3‐_MONO species elevated O_V hydrophobicity and O_M mobility for P300, which were pivotal to enhance its H₂O resistance and redox cycle efficiency over P400-P500, respectively. Conversely, PO₄^3‐_BI species outperformed PO₄^3‐_MONO counterparts in achieving higher O_L 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 (S₂O₇^2- of dehydrated ABS) fragmentation among P300–500, thereby unveiling higher ABS resistance than P300-P400 and bi-dentate SO₃^2-/SO₄^2--ample MnV₂O₆ control with humid, poisonous gases being fed.