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Preparation and Surface Composition of Tungsten Carbide Powders with High Specific Surface Area.-β-W2C is prepared by reaction of WO3 with NH3 at 1000 K followed by carburization of the resulting β-W2N in CH4/H2 at 1150 K. WC is prepared by carburization of WO3 in CH4/H2 at 1100 K. The β-W2C and WC powders have specific surface areas as high as 100 and 30 m2/g, respectively. The carbides are characterized by selective chemisorption (H2, CO, O2) and by temp.-programmed reduction and desorption experiments. -(RIBEIRO, F. H.; DALLA BETTA, R. A.; GUSKEY, G. J.; BOUDART, M.; Chem. Mater. 3 (1991) 5, 805-812; Dep. Chem. Eng., Stanford Univ., Stanford, CA 94305-5025, USA; EN)