Acid-Functionalized SBA-15-Type Periodic Mesoporous Organosilicas and Their Use in the Continuous Production of 5-Hydroxymethylfurfural
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- 作者：Mark H. Tucker ; Anthony J. Crisci ; Bethany N. Wigington ; Neelay Phadke ; Ricardo Alamillo ; Jinping Zhang ; Susannah L. Scott ; James A. Dumesic
- 刊名：ACS Catalysis
- 出版年：2012
- 出版时间：September 7, 2012
- 年：2012
- 卷：2
- 期：9
- 页码：1865-1876
- 全文大小：691K
- 年卷期：v.2,no.9(September 7, 2012)
- ISSN：2155-5435
文摘
The activity, selectivity, and stability of several supported acid catalysts were evaluated in tubular reactors designed to produce 5-hydroxymethylfurfural (HMF) continuously from fructose dissolved in a single-phase solution of THF and H2O (4:1 w/w). The reactors, packed with the solid catalysts, were operated at 403 K for extended periods, up to 190 h. The behaviors of three propylsulfonic acid-functionalized, ordered porous silicas (one inorganic SBA-15-type silica, and two ethane-bridged SBA-15-type organosilicas) were compared with that of a propylsulfonic acid-modified, nonordered, porous silica. The HMF selectivity of the catalysts with ordered pore structures ranged from 60 to 75%, whereas the selectivity of the nonordered catalyst under the same reaction conditions peaked at 20%. The latter was also the least stable, deactivating with a first-order rate constant of 0.152 h鈥?. The organosilicas are more hydrothermally stable and maintained a steady catalytic activity longer than the inorganic SBA-15-type silica. The organosilica with an intermediate framework ethane content of 45 mol % was more stable, with a first-order deactivation rate constant of only 0.012 h鈥?, than the organosilica containing 90 mol % ethane linkers in the framework. The catalysts were recovered and characterized after use by 13C and 29Si solid-state NMR, elemental analysis, nitrogen adsorption/desorption, X-ray diffraction, and SEM/TEM. Deactivation under flow conditions is caused primarily by hydrolytic cleavage of acid sites, which can be (to some) extent recaptured by the free surface hydroxyl groups of the silica surface.