Optimization of Redox Functionality Profiles of MoO3â€“V2O5/ TiO2 Composite Catalysts in Relation to Various Dispersion Patterns
Keywords:MoO3-V2O5 / TiO2, Redox reactivity, Dispersion parameters, Peroxo complexes.
AbstractAbstract: In the present study, a renewed approach was made to optimize the redox functionality of the well-known catalytic system MoO3-V2O5/ TiO2 (anatase) in relation to various dispersion patterns. Several types of composite catalysts were considered: xV/T (x of V2O5= 2-12 wt %), 6Mo-xV/T co-impregnates, yMo-8V/T co-impregnates (y of MoO3 = 3-9 wt %), 6Mo-doped 8V/T (coat 1) and 8V-doped Mo/T (coat 2). The samples were characterized by adopting the XRD, FTIR, ESR, TEM, N2 physisorption, high temperature H2-chemisorption and high temperature O2-chemisorptrion (HTOC), techniques. The redox reactivity was estimated in decomposition of H2O2 in highly concentrated solution, permitting the formation of several peroxo V intermediates. In xV/T system, the constancy of TON with loading indicated the involvement of single vanadia site, not sensitive to the surface dispersion, but rather depended on the nature of coordination of H2O2 molecules to VOx species. For different co-impregnates of Mo and V, the added molybdena, increasing the Lewis acidity, seemed to undergo a competitive interaction with titania to form non-reducible surface compound, with increased density of surface VOx patches. This was confirmed from H2-uptakes linked with highly stabilized V4+ species. The sample of coat 1had the same dispersion and reactivity patterns of the other members of co-impregnated series, with formation of non-reducible surface compound through Mo-O-V bridges. In coat 2 sample, the VOx species existed on the top surface of supported MoO3/TiO2 in a better dispersion state, with higher apparent density of surface patches, exhibiting comparable [A] and TON values to those of xV/T samples.
Policy for Journals/Articles with Open AccessAuthors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are permitted and encouraged to post links to their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work
Policy for Journals / Manuscript with Paid AccessAuthors who publish with this journal agree to the following terms:
- Publisher retain copyright .
- Authors are permitted and encouraged to post links to their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work .