M1 to M2 Phase Transformation and Phase Cooperation in Bulk Mixed Metal Mo–V–M–O (M=Te, Nb) Catalysts for Selective Ammoxidation of Propane
- 396 Downloads
In the present study we systematically explored hydrothermal synthesis of bulk mixed metal Mo–V–(Te–Nb)–O catalysts and investigated the bulk characteristics of the resulting M1 and M2 phases as well as their roles in the selective ammoxidation of propane. It was found that unlike Mo–V–Te–Nb–O M1 phases, the Mo–V–Te–O M1 phases may be quantitatively transformed into M2 phases of the same chemical composition indicating that Nb stabilizes the M1 structure. The stabilizing role of Nb and Te was further observed in high resolution TEM studies of Mo–V–(Te–Nb)–O catalysts which indicated that structural order and the M1 phase domain size progressively decreased in this order: Mo–V–Te–Nb–O > Mo–V–Te–O > Mo–V–O. The cooperation between the M1 and M2 phases in propane ammoxidation to acrylonitrile was observed only at low propane conversions suggesting that the M1 phase is the only crystalline phase required for the activity and selectivity of the Mo–V–Te–Nb–O catalysts in propane ammoxidation to acrylonitrile at practical propane conversions.
KeywordsPropane ammoxidation M1 phase Phase transformation Synergy
- 2.Ushikubo T, Nakamura H, Koyasu Y, Wajiki S (1995) US Patent 5,380,933Google Scholar
- 21.(a) Grasselli RK (2005) Catal Today 99:23; (b) Watanabe N, Ueda W (2006) Ind Eng Chem Res 45:607Google Scholar
- 38.Trunschke A, Schloegl R, Guliants VV, Knoester A, Brongersma HH (2006) Abstracts of Papers, 232nd ACS national meeting, San Francisco, CA, USA (Sept. 10–14)Google Scholar