Specialty chemicals
from sugars are destined to displace fermentation to alcohols due
to their superior economic value and atom efficiency. Compared to
bioethanol, retention of oxygen functional groups increases by 2–5
times the market value of specialty chemicals like furfural, 2,5-furan
dicarboxylic acid, 2,5-dimethyl furan, and γ-valerolactone.
For the first time, we report a gas-phase process that converts C-6
monosaccharides to furfural in a microfluidized bed reactor. A spray
nozzle inserted directly into the catalytic bed atomizes a fructose–water
solution to micron-sized droplets; water evaporates, and WO3/TiO2 converts fructose to furfural. Furfural yield reached
22% after 3 h time-on-stream with 15% diformyl furan as coproduct.
Acetic acid yield was mostly below 10% but was as high as 27%. During
the initial tests, coke and catalyst agglomerates blocked the sparger
tip, and run time varied between 1 and 3 h. Insulating the nozzle
leading into the bed reduced the injector wall temperature and improved
reactor operability; the 15 mm i.d. reactor ran continuously for 19
h after this modification.