TY - JOUR
T1 - Dehydroaromatization of methane over Sn-Pt modified Mo/H-ZSM-5 zeolite catalysts
T2 - Effect of preparation method
AU - Tshabalala, Themba E.
AU - Coville, Neil J.
AU - Anderson, James A.
AU - Scurrell, Michael S.
N1 - Acknowledgements
We wish to thank the National Research Foundation (NRF) South Africa, University of Aberdeen (Scotland, UK) and University of the Witwatersrand for financial support.
PY - 2015/8/25
Y1 - 2015/8/25
N2 - The effect of different catalyst preparation methods to make tin-platinum modified Mo/H-ZSM-5 zeolite catalysts for methane dehydroaromatization at 700 °C was investigated. The catalysts were prepared by both incipient wetness co-impregnation and sequential impregnation and calcined at 500 °C for 6 h. Catalysts prepared by the co-impregnation method showed a good platinum dispersion (10.8%), higher than found for the Pt/Sn and Sn/Pt sequentially impregnated catalysts (5.6% and 1.4%, respectively). Successive calcination treatments influenced the location of both tin and platinum in the catalyst and a decrease in platinum dispersion after reduction was evident from CO chemisorption studies. The order of sequentially loading platinum before or after tin had an effect on the electronic and structural properties of platinum as shown by XPS and FTIR studies. Different catalytic activities and aromatic selectivities were observed for the Pt/Sn and Sn/Pt catalysts. The co-impregnated Sn-Pt and the sequentially impregnated Pt/Sn catalysts showed high aromatic selectivity (>70%) and low coke selectivity (<20%). The decrease in coke selectivity is mainly dependent on the availability of platinum sites for hydrogenation of carbonaceous species.
AB - The effect of different catalyst preparation methods to make tin-platinum modified Mo/H-ZSM-5 zeolite catalysts for methane dehydroaromatization at 700 °C was investigated. The catalysts were prepared by both incipient wetness co-impregnation and sequential impregnation and calcined at 500 °C for 6 h. Catalysts prepared by the co-impregnation method showed a good platinum dispersion (10.8%), higher than found for the Pt/Sn and Sn/Pt sequentially impregnated catalysts (5.6% and 1.4%, respectively). Successive calcination treatments influenced the location of both tin and platinum in the catalyst and a decrease in platinum dispersion after reduction was evident from CO chemisorption studies. The order of sequentially loading platinum before or after tin had an effect on the electronic and structural properties of platinum as shown by XPS and FTIR studies. Different catalytic activities and aromatic selectivities were observed for the Pt/Sn and Sn/Pt catalysts. The co-impregnated Sn-Pt and the sequentially impregnated Pt/Sn catalysts showed high aromatic selectivity (>70%) and low coke selectivity (<20%). The decrease in coke selectivity is mainly dependent on the availability of platinum sites for hydrogenation of carbonaceous species.
KW - H-ZSM-5
KW - Methane dehydroaromatization
KW - Molybdenum
KW - Platinum
KW - Tin
UR - http://www.scopus.com/inward/record.url?scp=84938118173&partnerID=8YFLogxK
U2 - 10.1016/j.apcata.2015.06.035
DO - 10.1016/j.apcata.2015.06.035
M3 - Article
AN - SCOPUS:84938118173
VL - 503
SP - 218
EP - 226
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
SN - 0926-860X
ER -