Mechanism and Kinetic Study of Reducing MoO(3) to MoO(2) with CO–15 vol % CO(2) Mixed Gases

[Image: see text] In the present paper, the reduction reaction of high-purity MoO(3) with CO–15 vol % CO(2) mixed gases in the temperature range of 901–948 K is investigated via the thermogravimetric analysis technology. The results show that reduction of MoO(3) to MoO(2) follows a three-step reaction process, viz., MoO(3) is first reduced into Mo(9)O(26), followed by Mo(4)O(11), and finally to MoO(2). The reaction sequences of MoO(3) → Mo(9)O(26) → Mo(4)O(11) → MoO(2) are proposed, which are quite different from those observed on reduction of MoO(3) by pure H(2) or CO gases. Pure Mo(9)O(26) and Mo(4)O(11) could be synthesized once suitable time was controlled. Rate-controlling steps for the reduction from MoO(3) to Mo(9)O(26) and Mo(9)O(26) to MoO(2) (include both Mo(9)O(26) to Mo(4)O(11) and Mo(4)O(11) to MoO(2)) are interfacial chemical reactions, with the activation energies of 318.326 and 112.047 kJ/mol, respectively. This study also discovers that the as-synthesized MoO(2) keeps the same platelet-shaped and smooth morphology as the MoO(3) raw material; however, its particles size gradually increased as the reaction proceeds due to the formation of low-melting-point eutectic and the sticking of different particles.