Cellulose hydrolysis reactor incorporating stirring apparatus for use with carbon-based solid acid catalyst

Abstract

A highly efficient reactor with a stirring device was specially designed with the intent of performing the hydrolysis of pure crystalline cellulose using a carbon-based solid acid catalyst. This catalyst comprised an amorphous carbon-based material bearing -SO₃H, -COOH and -OH groups. The stirring apparatus had seven blades coated with polytetrafluoroethylene and arranged axially at regular intervals with a 60° offset. This design proved highly effective, providing double the glucose yield compared with conventional stirring systems. The basic properties of this novel reactor were investigated and analyzed and are discussed herein.

Keywords: Carbon-based solid acid catalyst; Cellulose hydrolysis; Reactor; Solid-solid interface reaction; Stirring apparatus.

Fig. 1

The new stirring apparatus developed in this work and the designs of conventional PTFE stirring devices. (a₁) The curved blades used in the 90 cm³ reactor (width, 43 mm, active height, 40 mm, blade thickness, 0.3 mm, see diagrams (i), (iii) and (iv)) and (a₂) the rhombic blades used in the 180 cm³ reactor (width, 58 mm, active height, 40 mm, blade thickness, 0.3 mm, see diagrams (ii), (iii) and (iv)). The rhombic blades used in the 90 cm³ reactor (width, 43 mm, active height, 40 mm, blade thickness, 0.3 mm. The two ends of each blade (6, 6.5 or 4.2 mm) were bent to ensure removal of any materials adhering to the reactor wall. (b) The screw-type, four-wing stirrer (width, 59 mm; active height, 15 mm), (c) the two-wing stirrer (width, 59 mm; active height, 15 mm) and (d) the W-type stirring wing device (width, 59 mm; active height, 40 mm). Upper right: Cylindrical PTFE reactors, each with a PTFE cap and PTFE stirring seal.

Fig. 2

Comparison of catalytic activities obtained using different mixing modes in conjunction with the curved blade stirring apparatus. The reaction conditions included a temperature of 373 K, a reaction time of 3 h, a solid acid catalyst loading of 3 g, a cellulose loading of 3 g, a water loading of 2.5 g, a stirring rate of 400 rpm and a reactor size of 90 cm³.

Fig. 3

Glucose yields from hydrolysis as functions of time. The reaction conditions included a reaction temperature of 373 K, a catalyst loading of 3 g, a cellulose loading of 0.9 g, a water loading of 1.6 g (blue), 2.5 g (red) or 3.75 g (black) and a stirring rate of 370 rpm.

Fig. 4

A comparison of the catalytic activities using various stirring apparatuses. Data are from (a₂) the newly developed rhombic blade stirring apparatus, (b) the screw-type, four-wing stirrer, (c) the two-wing stirrer and (d) the W-type stirring wing device. Data were obtained using a temperature of 373 K, a reaction time of 3 h, a solid acid catalyst loading of 6 g, a cellulose loading of 6 g, a water loading of 5 mL, a stirring rate of 400 rpm and a reactor size of 180 cm³.

Fig. 5

Comparison of the power requirements of the various stirring apparatuses. Data are from (a₂) the newly developed stirring apparatus with rhombic blades, (b) the screw-type, four-wing stirrer, (c) the two-wing stirrer and (d) the W-type stirring wing device. Results were obtained with a sampling rate of 500 Hz, a solid acid catalyst loading of 6 g, a cellulose loading of 6 g, a water loading of 5 mL, a stirring rate of 400 rpm and a reactor size of 180 cm³.

Fig. 6

Comparison of the efficiencies of various stirring apparatuses. Data were obtained from (a₂) the newly developed stirring apparatus with rhombic blades, (b) the screw-type, four-wing stirrer, (c) the two-wing stirrer and (d) the W-type stirring wing device.