Thermochemical Synthesis of Molybdenum Carbide on the Basis of the (NH4)6Mo7O24–NH4NO3–C6H12N4 System

Abstract

Data on the thermochemical synthesis of molybdenum carbide on the basis of the (NH₄)₆Mo₇O₂₄–NH₄NO₃–C₆H₁₂N₄ system at different component ratios have been reported. Thermodynamic computations have been performed to establish composition regions for probable exothermic reactions to produce molybdenum carbide: 10–20 moles of ammonium nitrate per 1 mole of ammonium molybdate and the ratio of reducing agent to oxidizing agent (φ) equal to 1.5–4.0. It has been found that the reaction in ammonium molybdate–ammonium nitrate–urotropin system includes several stages, the main exothermic reaction is observed after temperature of 120–180°C is reached. Molybdenum carbide forms at φ ≥ 6.5 after thermal treatment at 1000°C under inert atmosphere. The reaction leads to fine crystalline structure of particles with size of 100–200 nm. The obtained materials based on molybdenum carbide show catalytic activity in the conversion of products of incomplete combustion of biofuel (pyrolysis resins). Addition of the obtained materials to pyrolysis resin in 1/10 ratio enhances its conversion (rate parameter increases by 2–10 times), reduces average process temperature by 50–100°C, and decreases activation energy from 82 to 52–65 kJ/mol.