Comparative study of HSOA-/SOA2- versus H3−BPO4B- functionalities anchored on TiO2-supported antimony oxide-vanadium oxide-cerium oxide composites for low-temperature NOX activation

• Published in: Journal of hazardous materials 2021-08, Vol.416, p.125780, Article 125780
• Main Authors: Kim, Jongsik, Nam, Ki Bok, Ha, Heon Phil
• Format: Article
• Language: English
• Subjects: Activation energy; H3−BPO4B- functionality; HSOA-/SOA2- functionality; NOX consumption rate; Pre-factor; Selective catalytic NOX reduction
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.125780

TiO2-supported antimony oxide-vanadium oxide-cerium oxide (SVC) imparts Lewis acidic (L)/Brönsted acidic (B) sites, labile (Oα)/mobile oxygens (OM), and oxygen vacancies (OV) for selective catalytic NOX reduction (SCR). However, these species are harmonious occasionally, readily poisoned by H2O/sulfur/phosphorus/carbon, thus limiting SCR performance of SVC. Herein, a synthetic means is reported for immobilizing HSOA-/SOA2- (A= 3–4) or H3−BPO4B- (B= 1–3) on the L sites of SVC to form SVC-S and SVC-P. HSOA-/SOA2-/H3−BPO4B- acted as additional B sites with distinct characteristics, altered the properties of Oα/OM/OV species, thereby affecting the SCR activities and performance of SVC-S and SVC-P. SVC-P activated Langmuir-Hinshelwood-typed SCR better than SVC-S, as demonstrated by a greater Oα-directed pre-factor and smaller binding energy between Oα and NO. Meanwhile, SVC-S provided a larger B-directed pre-factor, thereby outperforming SVC-P in activating Eley-Rideal-typed SCR that dictated the overall SCR activities. Compared with SVC-S, SVC-P contained fewer OV species, yet, had higher OM mobility, thus enhancing the overall redox cycling feature, while providing greater Brönsted acidity. Consequently, the resistance of SVC-P to H2O or soot were greater than or similar to that of SVC-S. Conversely, SVC-S revealed greater tolerance to hydro-thermal aging and SO2 than SVC-P. This study highlights the pros and cons of HSOA-/SOA2-/H3−BPO4B- functionalities in tailoring the properties of metal oxides in use as SCR catalysts. [Display omitted] •Antimony oxide-vanadium oxide-cerium oxide on TiO2 is modified with HSOA-/SOA2- (SVC-S) or H3−BPO4B- (SVC-P).•SVC-S provides higher NOX reduction activity and larger quantity of oxygen vacancies than SVC-P.•SVC-P possesses greater Brönsted acidity and higher oxygen mobility than SVC-S.•SVC-S enhances the tolerance against SO2 and hydro-thermal aging over SVC-P.•SVC-P enhances the NOX reduction performance and resistance against H2O over SVC-S.