期刊
ACS CATALYSIS
卷 2, 期 9, 页码 1865-1876出版社
AMER CHEMICAL SOC
DOI: 10.1021/cs300303v
关键词
5-hydroxymethylfurfural; continuous dehydration; packed-bed reactor; SBA-15; periodic mesoporous organosilicas; propylsulfonic acid; catalyst deactivation rate
资金
- NSF under Center for Enabling New Technologies through Catalysis (CENTC)
- PIRE-ECCI (NSF) [OISE-0530268]
- MRSEC Program of the National Science Foundation [DMR05-20415]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [1121288] Funding Source: National Science Foundation
- Office Of The Director
- Office Of Internatl Science &Engineering [968399] Funding Source: National Science Foundation
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(-1). 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(-1), than the organosilica containing 90 mol % ethane linkers in the framework. The catalysts were recovered and characterized after use by C-13 and Si-29 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.
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