TY - JOUR
T1 - Enhancement of Molybdenum/ZSM-5 Catalysts in Methane Aromatization by the Addition of Iron Promoters and by Reduction/Carburization Pretreatment
AU - Sridhar, Apoorva
AU - Rahman, Mustafizur
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.
Publisher Copyright:
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/6/21
Y1 - 2018/6/21
N2 - The influence of an Fe additive and different types of pretreatment were studied on HZSM-5-supported molybdenum oxide (MoOx) catalysts for methane aromatization. The catalytic behavior of catalysts that consist of 6 wt % Mo/ZSM-5 with 0, 0.2, and 1 wt % Fe was tested with two types of pretreatment: 1) heating under He flow and 2) reduction in H2/CH4 and carburization in CH4. Under He pretreatment, the addition of 0.2 wt % Fe improved the benzene yield, but the addition of 1 % Fe decreased it slightly. Precarburization of the catalysts resulted in enhanced catalytic properties for all Fe loadings and improved the catalyst stability. The precarburized 6 wt % Mo–0.2 wt %Fe catalyst presented the highest benzene yield (6.9 %), which was almost stable in the subsequent 10 h test. The fresh and spent catalysts were characterized by using XRD, N2 adsorption, temperature-programmed reduction, SEM, temperature-programmed oxidation, and thermogravimetric analysis. The results show that the precarburized catalysts are more stable because of the formation of smaller amounts of carbon deposits and, consequently, less pore blockage. The addition of Fe causes the carbon deposits to be more reactive and easier to burn off. Higher Fe loadings are linked to the formation of carbon nanotubes.
AB - The influence of an Fe additive and different types of pretreatment were studied on HZSM-5-supported molybdenum oxide (MoOx) catalysts for methane aromatization. The catalytic behavior of catalysts that consist of 6 wt % Mo/ZSM-5 with 0, 0.2, and 1 wt % Fe was tested with two types of pretreatment: 1) heating under He flow and 2) reduction in H2/CH4 and carburization in CH4. Under He pretreatment, the addition of 0.2 wt % Fe improved the benzene yield, but the addition of 1 % Fe decreased it slightly. Precarburization of the catalysts resulted in enhanced catalytic properties for all Fe loadings and improved the catalyst stability. The precarburized 6 wt % Mo–0.2 wt %Fe catalyst presented the highest benzene yield (6.9 %), which was almost stable in the subsequent 10 h test. The fresh and spent catalysts were characterized by using XRD, N2 adsorption, temperature-programmed reduction, SEM, temperature-programmed oxidation, and thermogravimetric analysis. The results show that the precarburized catalysts are more stable because of the formation of smaller amounts of carbon deposits and, consequently, less pore blockage. The addition of Fe causes the carbon deposits to be more reactive and easier to burn off. Higher Fe loadings are linked to the formation of carbon nanotubes.
KW - carbon
KW - iron
KW - molybdenum
KW - supported catalysts
KW - zeolites
UR - http://www.scopus.com/inward/record.url?scp=85046293853&partnerID=8YFLogxK
U2 - 10.1002/cctc.201800002
DO - 10.1002/cctc.201800002
M3 - Article
AN - SCOPUS:85046293853
SN - 1867-3880
VL - 10
SP - 2571
EP - 2583
JO - ChemCatChem
JF - ChemCatChem
IS - 12
ER -