TY - JOUR
T1 - Impact of the presence of Mo carbide species prepared ex situ in Mo/HZSM-5 on the catalytic properties in methane aromatization
AU - Rahman, Mustafizur
AU - Sridhar, Apoorva
AU - Khatib, Sheima J.
N1 - Funding Information:
The authors acknowledge the financial support received from Texas Tech University . The authors would like to thank Dr. Daniel Unruh from the Department of Chemistry and Biochemistry for his help in acquiring the XRD patterns. The authors thank Dr. Antonia Infantes-Molina from the University of Malaga for performing the 27 Al-NMR measurements.
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/5/25
Y1 - 2018/5/25
N2 - The catalytic activity of HZSM-5 supported Mo-oxide (MoOx) and Mo-carbide (MoCy) for methane aromatization was studied using a packed-bed microreactor. MoOx/HZSM-5 catalysts with 3, 6, 10, and 12 wt.% Mo loading were prepared by incipient wetness impregnation method followed by calcination at 500 °C. The MoCy/HZSM-5 catalysts were prepared ex situ by treating the oxide catalysts by temperature-programmed reduction and carburization. The MoCy/HZSM-5 catalysts show significantly higher activities and stability compared to those of the MoOx/HZSM-5 catalysts. Unlike the oxide catalysts, not only methane conversion and benzene yield improve with higher Mo loading but also the deactivation rate becomes much slower for the carbide catalysts. The optimum carbide catalyst has a Mo loading of 10 wt% The catalysts were characterized by XRD, N2 adsorption, TPR, NH3-TPD, TPO,TGA and 27Al-NMR. The results show that the oxide catalysts at a high loading face pore blockage after few hours of reaction, which makes the active sites inaccessible to CH4. Carbide catalysts, on the other hand face no pore blockage even after a long period of reaction, making them much better catalysts than the oxides for nonoxidative methane aromatization reaction.
AB - The catalytic activity of HZSM-5 supported Mo-oxide (MoOx) and Mo-carbide (MoCy) for methane aromatization was studied using a packed-bed microreactor. MoOx/HZSM-5 catalysts with 3, 6, 10, and 12 wt.% Mo loading were prepared by incipient wetness impregnation method followed by calcination at 500 °C. The MoCy/HZSM-5 catalysts were prepared ex situ by treating the oxide catalysts by temperature-programmed reduction and carburization. The MoCy/HZSM-5 catalysts show significantly higher activities and stability compared to those of the MoOx/HZSM-5 catalysts. Unlike the oxide catalysts, not only methane conversion and benzene yield improve with higher Mo loading but also the deactivation rate becomes much slower for the carbide catalysts. The optimum carbide catalyst has a Mo loading of 10 wt% The catalysts were characterized by XRD, N2 adsorption, TPR, NH3-TPD, TPO,TGA and 27Al-NMR. The results show that the oxide catalysts at a high loading face pore blockage after few hours of reaction, which makes the active sites inaccessible to CH4. Carbide catalysts, on the other hand face no pore blockage even after a long period of reaction, making them much better catalysts than the oxides for nonoxidative methane aromatization reaction.
KW - Carbon deposits
KW - Deactivation
KW - Methane aromatization
KW - Mo/HZSM5
KW - MoC
KW - MoO
KW - Molybdenum carbide
UR - http://www.scopus.com/inward/record.url?scp=85044942467&partnerID=8YFLogxK
U2 - 10.1016/j.apcata.2018.03.023
DO - 10.1016/j.apcata.2018.03.023
M3 - Article
AN - SCOPUS:85044942467
VL - 558
SP - 67
EP - 80
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
SN - 0926-860X
ER -