TY - JOUR
T1 - The effect of calcination temperature on the catalytic performance of 2 wt.% Mo/HZSM-5 in methane aromatization
AU - Tan, P. L.
AU - Leung, Y. L.
AU - Lai, S. Y.
AU - Au, C. T.
N1 - Funding Information:
The work described above was fully supported by a grant (FRG/99-00/II-25) from the Hong Kong Baptist University. P.L. Tan thanks the HKBU for a Ph.D. studentship.
PY - 2002/3/28
Y1 - 2002/3/28
N2 - We observed that, at a calcination temperature (Tc) of 500 or 700 °C, the catalytic performance of 2wt.% Mo/HZSM-5 for methane aromatization was compatible with that reported in the literature. When Tc was set at or above 750 °C, the catalyst deactivated and ethylene was the dominant product. The results of our analytic studies suggested that at Tc = 500 °C, the Mo species were not uniformly distributed, but existed as microcrystalline MoO3, polymolybdate, and other Mo entities. At Tc = 700 °C, Mo species were dispersed on the external surface as well as diffused into the channels of the zeolite. At or above a calcination temperature of 750 °C, dealumination as well as reduction in crystallinity of the zeolite became considerable. The results of atomic absorption spectrophotometric analysis confirmed that the loss of Mo during calcination was insignificant. With the partial destruction of HZSM-5 zeolite and the disappearance of Brønsted acid sites, the 2wt.% Mo/HZSM-5 material ceased to function as a catalyst for methane aromatization.
AB - We observed that, at a calcination temperature (Tc) of 500 or 700 °C, the catalytic performance of 2wt.% Mo/HZSM-5 for methane aromatization was compatible with that reported in the literature. When Tc was set at or above 750 °C, the catalyst deactivated and ethylene was the dominant product. The results of our analytic studies suggested that at Tc = 500 °C, the Mo species were not uniformly distributed, but existed as microcrystalline MoO3, polymolybdate, and other Mo entities. At Tc = 700 °C, Mo species were dispersed on the external surface as well as diffused into the channels of the zeolite. At or above a calcination temperature of 750 °C, dealumination as well as reduction in crystallinity of the zeolite became considerable. The results of atomic absorption spectrophotometric analysis confirmed that the loss of Mo during calcination was insignificant. With the partial destruction of HZSM-5 zeolite and the disappearance of Brønsted acid sites, the 2wt.% Mo/HZSM-5 material ceased to function as a catalyst for methane aromatization.
KW - Calcination temperature
KW - Dealumination
KW - Methane aromatization
KW - Mo/HZSM-5
KW - Polymolybdate
UR - http://www.scopus.com/inward/record.url?scp=0036090509&partnerID=8YFLogxK
U2 - 10.1016/S0926-860X(01)00955-3
DO - 10.1016/S0926-860X(01)00955-3
M3 - Journal article
AN - SCOPUS:0036090509
SN - 0926-860X
VL - 228
SP - 115
EP - 125
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
IS - 1-2
ER -