科研之友
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摘要
Anisole hydrodeoxygenation over a nonsulfided CoMo/Al2O3 catalyst was investigated as a model reaction for fast pyrolysis oil upgrading. Intrinsic kinetic data have been acquired in a gas-phase plug-flow reactor at temperatures ranging from 548 to 623 K, a total pressure amounting to 0.5 MPa, a space time between 95 and 400 kg(cat) s mol(anisoie)(-1), and a hydrogen to anisole molar ratio from 50 to 400. A minimum of 16 h on stream stable anisole conversion was observed. The catalyst mainly exhibited anisole demethylation and phenol methylation to cresol, rather than hydrogenation or hydrodeoxygenation. Demethylation and isomerization reactions are followed by hydrodeoxygenation. Additionally, cresol is formed via phenol methylation. Rival mechanisms were proposed, and corresponding Langmuir-Hinshelwood-Hougen-Watson elementary step based kinetic models were derived. Each of the proposed models accounted for the interaction of the species with the catalyst surface as well as for the surface reactions. For each catalytic cycle a rate-determining step was identified. Statistical analysis combined with an assessment of physical meaning of the model parameters allowed the proposal that for both demethylation and hydrodeoxygenation reactions C-Ar-O bond cleavage is facilitated by a prior hydrogen addition. Cresol is mainly formed from phenol methylation rather than from anisole isomerization occurring at a rate which is several orders of magnitude slower than that of the other reactions considered.
- 出版日期2017-7
