TY - JOUR
T1 - Characterization and reactivity of Ga+ and GaO+ cations in zeolite ZSM-5
AU - Rane, N.J.
AU - Overweg, A.R.
AU - Kazansky, V.B.
AU - Santen, van, R.A.
AU - Hensen, E.J.M.
PY - 2006
Y1 - 2006
N2 - The reduction of Ga(CH3)3/ZSM-5 was closely followed by Fourier transform infrared spectroscopy and Ga K-edge X-ray absorption near-edge spectroscopy. Chemical vapor deposition of trimethylgallium on HZSM-5 (TMG/ZSM-5) resulted in the replacement of nearly all Brønsted acid protons by dimethylgallium species. Removal of the methyl ligands from the cationic Ga clusters gave charge-compensating Ga+ and species. At high temperatures and in the absence of hydrogen, the Ga+ species were the most stable, although decomposition of the species was very slow. Ga+ ions can be oxidized by nitrous oxide at low temperature (473 K), resulting in the formation of gallyl (GaO+) cations. A detailed comparison of the reactivity of Brønsted acid protons (HZSM-5) and Ga+ ions (reduced TMG/ZSM-5) in propane dehydrogenation showed that the former converted propane via protolytic cracking with methane, ethane, and propene as hydrocarbon products, whereas monovalent Ga+ ions produced propene almost exclusively. The reaction data suggest that propane was converted over Ga+ cations but not over cations. The initial rate of propane dehydrogenation was highest for GaO+ ions, although rapid deactivation was observed, due to the higher barrier for regeneration of GaO+ ions than for formation of less active Ga+ ions.
ERRATUM : Journal of Catalysis, Volume 240, Issue 1, 15 May 2006, Page 85,
AB - The reduction of Ga(CH3)3/ZSM-5 was closely followed by Fourier transform infrared spectroscopy and Ga K-edge X-ray absorption near-edge spectroscopy. Chemical vapor deposition of trimethylgallium on HZSM-5 (TMG/ZSM-5) resulted in the replacement of nearly all Brønsted acid protons by dimethylgallium species. Removal of the methyl ligands from the cationic Ga clusters gave charge-compensating Ga+ and species. At high temperatures and in the absence of hydrogen, the Ga+ species were the most stable, although decomposition of the species was very slow. Ga+ ions can be oxidized by nitrous oxide at low temperature (473 K), resulting in the formation of gallyl (GaO+) cations. A detailed comparison of the reactivity of Brønsted acid protons (HZSM-5) and Ga+ ions (reduced TMG/ZSM-5) in propane dehydrogenation showed that the former converted propane via protolytic cracking with methane, ethane, and propene as hydrocarbon products, whereas monovalent Ga+ ions produced propene almost exclusively. The reaction data suggest that propane was converted over Ga+ cations but not over cations. The initial rate of propane dehydrogenation was highest for GaO+ ions, although rapid deactivation was observed, due to the higher barrier for regeneration of GaO+ ions than for formation of less active Ga+ ions.
ERRATUM : Journal of Catalysis, Volume 240, Issue 1, 15 May 2006, Page 85,
U2 - 10.1016/j.jcat.2006.03.004
DO - 10.1016/j.jcat.2006.03.004
M3 - Article
SN - 0021-9517
VL - 239
SP - 478
EP - 485
JO - Journal of Catalysis
JF - Journal of Catalysis
IS - 2
ER -