NON-STOICHIOMETRIC TUNGSTEN CARBIDE

摘要

A compound useful for tungsten- and carbon-based hydrogenation reactions, having an atomic ratio between carbon and tungsten of 0.5-2, which ratio differs by at least 1 % from the stoichiometry of any given compound (of tungsten and carbon) in the same range. The method for preparing the compound comprises (a) a pre-processing step performed in an inert gas under tungsten oxide reaction conditions, preferably in nitrogen, by heating to a temperature of 150-1000 DEG C, preferably 400-600 DEG C, advantageously for at least one hour approximately; (b) a step of reducing/carbonising the compound from step (a) by contacting it with a hydrogen- and carbon-containing body at a preferred temperature of 600-1200 DEG C, advantageously 900-1100 DEG C; (c) an optional hydrogenation/decoking step in which the compound is contacted with hydrogen and optionally an inert gas at a temperature of 600-1200 DEG C, advantageously 700-1100 DEG C, and preferably 700-900 DEG C; and (d) an optional pyrophoricity reducing step in which the compound is contacted, at a temperature of 0-50 DEG C, and preferably at around 20 DEG C, with a gas that is inert for said compound and has an oxygen content advantageously lower than 5 %, and preferably no higher than 2 %, until said compound is no longer pyrophoric. The compound is useful in organic synthesis.