Microwave technology as a green and fast alternative for furfural production and biomass pre-treatment using corn stover: Energetic and economic evaluation

Pressurized microwave treatments were used for the production of furfural using three different pentosecontaining materials with different structural complexity levels; pure xylose, xylan from corn core and corn stover. Only water was used as the one-pot reaction medium, as an alternative to the frequently used organic solvents. The presence of CrCl3 as a Lewis acid catalyst was essential for furfural production. In general, higher temperature and longer treatments led to higher furfural yield, although treatment times over 40 minutes did not show any improvement. Using the severity factor (logR0) and the power consumption it was possible to determine that for equal furfural production treatments, it was more energy requiring to maintain a lower temperature during more time, than to perform shorten treatments at higher temperature. Best MW treatment conditions for xylose were 200 degrees C for 25 minutes, with a furfural yield of 43%, which corresponded to a logR0 of 2.56. When treating xylan and corn stover, lower furfural yields were achieved under these conditions due to higher energy requirements to break the structural components, being 39 and 23 %, respectively. When treating corn stover under these conditions, best energy consumption values per amount of generated furfural were found, being 0.8 kWh/ g furfural, what is equivalent to the emission of 195 g CO2/ g furfural, a much lower value than other MW tested conditions. MW treatments were proposed as a pre-treatment to enrich biomass in cellulose while producing furfural with an environmentally friendly technology.