Catalytic decomposition of 2-propanol over different metal-cation-doped OMS-2 materials

The catalytic properties of manganese oxide octahedral molecular sieve materials (OMS-2) with different metal cation dopants (M: Cu2+, Zn2+, Ni2+, Co2+, Al3+, or Mg2+) were investigated for the reaction of 2-propanol decomposition. Compared with other M-OMS-2 catalysts, Cu-OMS-2 catalyst has much higher conversion of 2-propanol and the highest selectivity to acetone at 300 degreesC. As for the selectivity to propene, it is generally below 6% for M-OMS-2 materials. The reaction results are discussed in consideration of characterization results of M-OMS-2 catalysts, especially studies on their acidity and basicity, and suggest that dehydrogenation of 2-propanol is not simply catalyzed by basic or acidic and basic pair sites, but probably by active sites with redox and basic properties. In situ FTIR studies suggest that Cu-OMS-2 has more active sites for 2-propanol than Al-OMS-2 and K-OMS-2. The phase transitions from cryptomelane to hausmannite and finally to manganosite were observed with XRD studies of Cu-OMS-2 catalysts during reaction. All Cu-OMS-2 materials that either have the cryptomelane, amorphous MnOy, hausmannite, or manganosite structure show activity in the decomposition of 2-propanol to acetone. The Cu-OMS-2 materials with the hausmannite structure show the highest activity. (C) 2001 Academic Press.