Kinetics and reaction engineering of levulinic acid production from aqueous glucose solutions.
We have developed a kinetic model for aqueous-phase production of levulinic acid from glucose using a homogeneous acid catalyst. The proposed model shows a good fit with experimental data collected in this study in a batch reactor. The model was also fitted to steady-state data obtained in a plug flow reactor (PFR) and a continuously stirred tank reactor (CSTR). The kinetic model consists of four key steps: (1) glucose dehydration to form 5-hydroxymethylfurfural (HMF); (2) glucose reversion/degradation reactions to produce humins (highly polymerized insoluble carbonaceous species); (3) HMF rehydration to form levulinic acid and formic acid; and (4) HMF degradation to form humins. We use our model to predict the optimal reactor design and operating conditions for HMF and levulinic acid production in a continuous reactor system. Higher temperatures (180-200 °C) and shorter reaction times (less than 1 min) are essential to maximize the HMF content. In contrast, relatively low temperatures (140-160 °C) and longer residence times (above 100 min) are essential for maximum levulinic acid yield. We estimate that a maximum HMF carbon yield of 14% can be obtained in a PFR at 200 °C and a reaction time of 10 s. Levulinic acid can be produced at 57% carbon yield (68% of the theoretical yield) in a PFR at 149 °C and a residence time of 500 min. A system of two consecutive PFR reactors shows a higher performance than a PFR and CSTR combination. However, compared to a single PFR, there is no distinct advantage to implement a system of two consecutive reactors.
Department of Chemical Engineering, University of Massachusetts Amherst, 686 North Pleasant St. 159 Goessmann Lab, Amherst, MA 01003, USA.
Ronen
R
Weingarten
Joungmo
J
Cho
Rong
R
Xing
William Curtis
WC
Conner
George W
GW
Huber
D005662:Furaldehyde / Q000031:analogs & derivatives / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry; D007700:Kinetics; D007982:Levulinic Acids / Q000737:chemistry*; D008956:Models, Chemical; D012996:Solutions; D014867:Water / Q000737:chemistry*
D007982:Levulinic Acids; D012996:Solutions; D014867:Water; C008046:5-hydroxymethylfurfural; D005662:Furaldehyde; D005947:Glucose; D006851:Hydrochloric Acid; C032246:levulinic acid