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Title: Increasing the catalytic stability by optimizing the formation of zeolite-supported Mo carbide species ex situ for methane dehydroaromatization

Journal Article · · Journal of Catalysis
 [1]; ORCiD logo [2];  [3];  [3];  [4];  [1];  [1]
  1. Texas Tech Univ., Lubbock, TX (United States)
  2. Univ. of Malaga (Spain)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. Brookhaven National Lab. (BNL), Upton, NY (United States)
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The synthesis of zeolite-supported Mo carbide species was investigated by testing different reduction/carburization conditions applied to a zeolite-supported Mo oxide catalyst, with the aim to find the optimized treatment conditions essential to form stable supported Mo carbide catalysts ex situ for application in methane dehydroaromatization reaction. Four types of treatment were performed and studied using temperature-programmed reduction and carburization profiles: (1) heating the catalyst in a reducing gas, H2, up to reaction temperature and switching to CH4; (2) heating the catalyst in a reducing gas, H2, mixed with dilute CH4; (3) heating the catalyst in CH4 up to reaction temperature; and (4) heating the catalyst in an inert gas (commonly He) up to reaction temperature and then switching to CH4 or to H2 followed by CH4 or to H2/CH4 mixture. Each of these processes were stopped at intermediate points to analyze the phases that were present in order to identify the structural evolution of the supported Mo carbides that originate from the supported Mo oxides. Once the supported carbides were formed, they were quenched under the same gas mixture, and then they were each tested in methane dehydroaromatization via previous heating to reaction temperature in He flow. Despite all of them showing only presence of Mo2C species on HZSM-5, the catalytic properties were dramatically different. Catalysts treated in H2 or CH4/H2 showed remarkably higher stability. These catalysts reflected a higher Mo dispersion and thus exposure on the active surface.

Research Organization:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division
Grant/Contract Number:
SC0012704
OSTI ID:
1571403
Alternate ID(s):
OSTI ID: 1529651
Report Number(s):
BNL-212215-2019-JAAM
Journal Information:
Journal of Catalysis, Vol. 375, Issue C; ISSN 0021-9517
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 19 works
Citation information provided by
Web of Science

Figures / Tables (18)

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36 MATERIALS SCIENCE
MoO3
Mo2C
Supported molybdenum carbide
Methane dehydroaromatization
Temperature programmed reduction and carburization