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کاتالیزور کاربردی a: عمومی 2012
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  • cu/sio2 hybrid catalysts containing hzsm-5 with enhanced activity and stability for selective hydrogenation of dimethyl oxalate to ethylene glycol

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    • تاریخ ارائه: 1392/07/24
    • تاریخ انتشار در تی پی بین: 1392/07/24
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     a novel type of hybrid catalysts composed of cu/sio2 and h-form zsm-5 (hzsm-5) zeolite, prepared using urea-assisted gelation method, displayed excellent catalytic activity and stability for the selective hydrogenation of dimethyl oxalate (dmo) to ethylene glycol (eg). the content and sio2/al2o3 ratio of hzsm-5 significantly influenced the performance of hybrid catalysts. an unprecedentedly high eg space time yield of 1.50 g g-cat−1 h−1, with dmo conversion of 99.5% and eg selectivity of 94.8%, were obtained on a hybrid catalyst containing 3 wt% of hzsm-5 with sio2/al2o3 = 38. the characterizations of n2physisorption and n2o chemisorptions revealed that both specific surface area and copper dispersion were promoted by introducing hzsm-5 zeolite into the cu/sio2 catalyst. moreover, x-ray auger electron spectroscopy and in situ fourier transform infrared spectroscopy of chemisorbed co demonstrated that the surface cu+ site concentration of the catalysts containing hzsm-5 was higher than those without hzsm-5. the results indicated that the introduction of hzsm-5 zeolite changed the crystallization behaviors of cupric phyllosilicate precursor, essentially improving copper dispersion and enhancing copper–silica interaction. furthermore, the specific zeolitic cages and negatively charged framework of hzsm-5 zeolite incorporated into cu/sio2 entities might also be beneficial for accommodation and stabilization of highly dispersed cuprous species, which act as efficient active sites for the activation of ester groups.

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