화학공학소재연구정보센터
Applied Catalysis A: General, Vol.445, 35-41, 2012
Autothermal reforming of butanol to butenes in a staged millisecond reactor: Effect of catalysts and isomers
Dehydration and isomerization of butanol is studied in an autothermal short contact-time reactor containing a 1 wt% Pt stage followed by a zeolite or gamma-Al2O3 stage downstream to convert butanol into butenes with up to 95% yield at residence times on the order of 100 ms. CH4 is fed as a sacrificial fuel to the Pt stage and butanol is fed between the stages to avoid undesired oxidation and reforming reactions of butanol over Pt. The energy released by CH4 catalytic partial oxidation drives downstream butanol dehydration and isomerization. The effect of catalyst is studied by comparing the performance of HZSM-5, HFER, and gamma-Al2O3 catalysts. Higher yields (20%) of butenes were obtained with gamma-Al2O3 and HFER than with HZSM-5. The absence of Bronsted acid sites in gamma-Al2O3 and the small pore structure of HFER lead to reduced yields of large side products such as higher hydrocarbons that promote oligomerization reactions. A 95% butene yield is obtained with HFER at temperatures ranging from 280-350 degrees C and a 95% yield with gamma-Al2O3 at temperatures between 320 and 350 degrees C. Only a 75% butene yield was obtained with HZSM-5 at 230 degrees C. The effect of hydrocarbon structure on product formation is studied by comparing conversions of each butanol isomer using a heated tube reactor at temperatures between 200 and 400 degrees C. The reactivity of butanol follows as: t-butanol > 2-butanol > iso-butanol > 1-butanol. trans-2-Butene and cis-2-butene are primarily formed from linear butanol isomers, while isobutene forms from branched butanol isomers. Conversions and product distributions of butanol isomers formed over HZSM-5 in a staged reactor are comparable (<10% difference across all species) with data using a heated tube reactor at similar temperatures. We successfully demonstrate an alternative pathway to dehydrate butanol into butenes with an autothermal staged reactor compared to conventional methods for applications in small-scale biomass utilization. The largest advantage of this reactor is the integration of highly exothermic autothermal stage and endothermic alcohol dehydration stage which provides an alternative processing technique to maintain the bed temperature. (C) 2012 Elsevier B.V. All rights reserved.