Colloquia

Summary

The 1990s set the start of finding efficient ways to reduce the chemical industry's greenhouse gas (GHG) emissions. One of the most studied ways to do it is using biomass to produce chemicals. In this work, we focused on producing ethylene glycol (EG). Its production is possible through biomass hydrogenolysis, which uses cellulose of lignocellulosic biomass. Although yields above 20 wt.% have been obtained, they are still low and come from converting 5% biomass, which makes them unsuitable for industrial scale. Thus, the purpose of this work was to increase the EG yield while converting more biomass in a batch autoclave. However, biomass has another valuable component: lignin. Although it is more difficult to convert than cellulose, a process called Reductive Catalytic Fractionations (RCF) has fully extracted it from biomass and selectively converted it into high-value-added monomers. Interestingly, it has similar reaction conditions to biomass hydrogenolysis: a high temperature, a catalyst, a reductive environment, and an acidic liquid solvent. Hence, this work also evaluated if lignin upgrading was simultaneously possible with similar results to RCF.

By studying the conditions RCF and biomass hydrogenolysis share (temperature, catalyst, hydrogen, and pH), we determined that lignin cannot be converted as successfully as with RCF because of the fast kinetics of cellulose.  This result suggests that the polymers should follow an independent upgrading from cellulose. However, the result is still meaningful because it demonstrates that biomass does not need a total delignification for good EG production. 

On the other hand, this research achieved a significant EG yield increase to 34 wt.% with 10% biomass. It translates to almost three times the mass of EG of the first experiment (from 0.12 to 0.37 g) with a slight increase of resources (from 245°C to 260°C and from a catalyst ratio of 0.3 to 0.93).