Svelle Stian, Olsbye Unni, Lillerud Karl-Petter, Kolboe Stein, Bjørgen Morten
Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, Norway.
J Am Chem Soc. 2006 May 3;128(17):5618-9. doi: 10.1021/ja060931w.
Despite their vital roles in the catalytic cycle for toluene disproportionation, diphenylmethane (DPM)-type compounds have never been directly detected or proved to be true reaction intermediates from experimental techniques. In this report, we provide unprecedented insights into the DPM-mediated reaction mechanism, by demonstrating the build-up of DPM species inside the zeolite pores and following their decomposition. It can be stated that, despite their bulkiness, (di)methylated DPM species may indeed be formed at high concentrations in the ZSM-5 channels when toluene is reacted. The dimethyl-DPM species are unstable when present in the zeolite voids and decompose under a concomitant evolution of xylene at 200 degrees C.
尽管二苯基甲烷（DPM）型化合物在甲苯歧化催化循环中起着至关重要的作用，但从未通过实验技术直接检测到它们或证明它们是真正的反应中间体。在本报告中，我们通过展示沸石孔内DPM物种的积累并跟踪其分解过程，对DPM介导的反应机理提供了前所未有的见解。可以说，尽管（二）甲基化的DPM物种体积较大，但当甲苯发生反应时，它们确实可能在ZSM-5通道中以高浓度形成。二甲基-DPM物种存在于沸石空隙中时不稳定，在200℃伴随着二甲苯的生成而分解。
