Assessment of micropore accessibility for hydrocarbon oxidation in manganese oxide sieves

Recent Advances in Tetra- (Ti, Sn, Zr, Hf) and Pentavalent (Nb, V, Ta) Metal-Substituted Molecular Sieve Catalysis

“…Similar shape selectivity studies in selective oxidations have been performed with microporous manganese oxide systems, some of which doped with vanadium . More specifically, various octahedral molecular sieve (OMS) systems with channels consisting of edge-shared MnO 6 octahedra of different sizes (OMS-1, OMS-2, OMS-5, and OMS-6) were tested for ethane and cyclohexane ODH and compared with commercial manganese (MnO), MoVTeNb (M1), and vanadium (V 2 O 5 ) oxides .…”

“…262 Similar shape selectivity studies in selective oxidations have been performed with microporous manganese oxide systems, some of which doped with vanadium. 263 More specifically, various octahedral molecular sieve (OMS) systems with channels consisting of edge-shared MnO 6 octahedra of different sizes (OMS-1, OMS-2, OMS-5, and OMS-6) were tested for ethane and cyclohexane ODH and compared with commercial manganese (MnO), MoVTeNb (M1), and vanadium (V 2 O 5 ) oxides. 263 As in studies described above, ethane and cyclohexane accessibility to the channels and internal sites of these OMS systems was examined by DFT modeling, showing that the ethane and cyclohexane ODH rates over OMS materials were higher than those over commercial manganese oxide, MnO 2 , MoVTeNbO x , and vanadia and that the C 2 H 6 /C 6 H 12 rate ratios over OMS oxides were higher than over vanadia accordingly.…”

“…263 More specifically, various octahedral molecular sieve (OMS) systems with channels consisting of edge-shared MnO 6 octahedra of different sizes (OMS-1, OMS-2, OMS-5, and OMS-6) were tested for ethane and cyclohexane ODH and compared with commercial manganese (MnO), MoVTeNb (M1), and vanadium (V 2 O 5 ) oxides. 263 As in studies described above, ethane and cyclohexane accessibility to the channels and internal sites of these OMS systems was examined by DFT modeling, showing that the ethane and cyclohexane ODH rates over OMS materials were higher than those over commercial manganese oxide, MnO 2 , MoVTeNbO x , and vanadia and that the C 2 H 6 /C 6 H 12 rate ratios over OMS oxides were higher than over vanadia accordingly. The authors also analyzed selectivity based on ethane accessibility in small pores and on ethane and cyclohexane accessibility in large pores, in addition to the role of defects, finding that ethylene selectivity was somewhat higher in smaller pores, thereby indicating potential relationships between selectivity and pore confinement.…”

“…The authors also analyzed selectivity based on ethane accessibility in small pores and on ethane and cyclohexane accessibility in large pores, in addition to the role of defects, finding that ethylene selectivity was somewhat higher in smaller pores, thereby indicating potential relationships between selectivity and pore confinement. 263 5.1.4. Other Oxidation Reactions.…”

DFT based microkinetic modeling of confinement driven [4 + 2] Diels–Alder reactions between ethene and isoprene in H-ZSM5

“…Overstabilizing adsorbates is also possible, and has been shown to impede reaction rates through increased diffusion limitations, 12,13 restrained product desorption, and increased intrinsic reaction barriers. 14 However confinement is not exclusive to zeolites, and has been shown to be a significant factor in catalyzing the oxidative dehydrogenation of hydrocarbons within mixed metaloxides 15,16 and manganese oxide based octahedral molecular sieves, 17 as well as catalyzing Diels-Alder reactions within macromolecules. 18 Understanding confinement is therefore a multifaceted problem, and despite our detailed understanding on an individual basis, our mechanistic understanding and ability to make empirical predictions remains limited.…”