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Title: Compared activities of platinum and high specific surface area Mo[sub 2]C and WC catalysts for reforming reactions

Abstract

The catalytic properties of high specific surface area (> 150 m[sup 2]/g) molybdenum and tungsten carbides are studied in hydrocarbon-reforming reactions and compared to conventional platinum supported on alumina. The isomerization of n-hexane is used as a test reaction. TPR and XPS analyses show that the raw materials are contaminated by oxygen and need an activation process to become reactive. These analyses also show that Mo[sub 2]C is decomposed by pure hydrogen at 800 C to form methane and metallic molybdenum. Different methods of reductive activation are tested: high-temperature reduction (800 C) by hydrogen leads to metallic Mo and W on the surface (catalytically unreactive for reforming); coreduction by a mixture of pentane and hydrogen (700 C) gives active catalysts but less so than conventional platinum, probably because of the presence of carboneous residues formed by decomposition of the n-pentane. Trace amounts of different group VIII transition metals ([le] 500 ppm) can catalyze the activation process, probably by preventing the formation of the carboneous residues. Mo[sub 2]C activated by 500 ppm of Pt, Ir, or Ru can reach total specific activities 6 to 7 times higher than the conventional Pt catalyst. However in terms of yield, the best carbide, activatedmore » by Ir, only doubles the performance of conventional platinum, with a high amount of cracked molecules formed in parallel. Clean surfaces of Mo[sub 2]C or WC can be much more reactive than conventional Pt catalysts in terms of specific activity, isomerization, plus cracking; however, the best selectivity in isomers never exceeds 30% while selectivity on Pt is usually in the range 75 to 85%.« less

Authors:
;  [1];  [2];  [3]
  1. Univ. Louis Pasteur, Strasbourg (France)
  2. IPCMS, EHICS, Strasbourg (France)
  3. Centre de Recherche de Voreppe (France)
Publication Date:
OSTI Identifier:
6994260
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis; (United States)
Additional Journal Information:
Journal Volume: 134:2; Journal ID: ISSN 0021-9517
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; HEXANE; CATALYTIC REFORMING; MOLYBDENUM CARBIDES; CATALYTIC EFFECTS; PLATINUM; TUNGSTEN CARBIDES; ALUMINIUM OXIDES; CATALYST SUPPORTS; CHEMICAL ACTIVATION; CHEMICAL REACTION YIELD; COMPARATIVE EVALUATIONS; DECOMPOSITION; IRIDIUM; ISOMERIZATION; METHANE; MOLYBDENUM; PENTANE; PETROLEUM; PHOTOELECTRON SPECTROSCOPY; PROMOTERS; REDUCTION; REFINING; RUBIDIUM; SURFACE AREA; SYNTHESIS; TEMPERATURE CONTROL; TUNGSTEN; X-RAY SPECTROSCOPY; ALKALI METALS; ALKANES; ALUMINIUM COMPOUNDS; CARBIDES; CARBON COMPOUNDS; CHALCOGENIDES; CHEMICAL REACTIONS; CONTROL; ELECTRON SPECTROSCOPY; ELEMENTS; ENERGY SOURCES; EVALUATION; FOSSIL FUELS; FUELS; HYDROCARBONS; METALS; MOLYBDENUM COMPOUNDS; ORGANIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PLATINUM METALS; PROCESSING; REFORMER PROCESSES; REFRACTORY METAL COMPOUNDS; SPECTROSCOPY; SURFACE PROPERTIES; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; TUNGSTEN COMPOUNDS; YIELDS; 020400* - Petroleum- Processing

Citation Formats

Ledoux, M J, Huu, Cuong Pham, Guille, J, and Dunlop, H. Compared activities of platinum and high specific surface area Mo[sub 2]C and WC catalysts for reforming reactions. United States: N. p., 1992. Web. doi:10.1016/0021-9517(92)90329-G.
Ledoux, M J, Huu, Cuong Pham, Guille, J, & Dunlop, H. Compared activities of platinum and high specific surface area Mo[sub 2]C and WC catalysts for reforming reactions. United States. doi:10.1016/0021-9517(92)90329-G.
Ledoux, M J, Huu, Cuong Pham, Guille, J, and Dunlop, H. Wed . "Compared activities of platinum and high specific surface area Mo[sub 2]C and WC catalysts for reforming reactions". United States. doi:10.1016/0021-9517(92)90329-G.
@article{osti_6994260,
title = {Compared activities of platinum and high specific surface area Mo[sub 2]C and WC catalysts for reforming reactions},
author = {Ledoux, M J and Huu, Cuong Pham and Guille, J and Dunlop, H},
abstractNote = {The catalytic properties of high specific surface area (> 150 m[sup 2]/g) molybdenum and tungsten carbides are studied in hydrocarbon-reforming reactions and compared to conventional platinum supported on alumina. The isomerization of n-hexane is used as a test reaction. TPR and XPS analyses show that the raw materials are contaminated by oxygen and need an activation process to become reactive. These analyses also show that Mo[sub 2]C is decomposed by pure hydrogen at 800 C to form methane and metallic molybdenum. Different methods of reductive activation are tested: high-temperature reduction (800 C) by hydrogen leads to metallic Mo and W on the surface (catalytically unreactive for reforming); coreduction by a mixture of pentane and hydrogen (700 C) gives active catalysts but less so than conventional platinum, probably because of the presence of carboneous residues formed by decomposition of the n-pentane. Trace amounts of different group VIII transition metals ([le] 500 ppm) can catalyze the activation process, probably by preventing the formation of the carboneous residues. Mo[sub 2]C activated by 500 ppm of Pt, Ir, or Ru can reach total specific activities 6 to 7 times higher than the conventional Pt catalyst. However in terms of yield, the best carbide, activated by Ir, only doubles the performance of conventional platinum, with a high amount of cracked molecules formed in parallel. Clean surfaces of Mo[sub 2]C or WC can be much more reactive than conventional Pt catalysts in terms of specific activity, isomerization, plus cracking; however, the best selectivity in isomers never exceeds 30% while selectivity on Pt is usually in the range 75 to 85%.},
doi = {10.1016/0021-9517(92)90329-G},
journal = {Journal of Catalysis; (United States)},
issn = {0021-9517},
number = ,
volume = 134:2,
place = {United States},
year = {1992},
month = {4}
}