Fermentation of cellulose pyrolysis oil by a Clostridial bacterium

Abstract

The coupling of thermochemical and biological conversion of biomass is a promising strategy to produce chemicals in future integrated biorefineries. Indeed, thermochemical conversion such as pyrolysis is a fast process without any solvent or enzyme for the depolymerization of biomass. In this work, cellulose was pyrolyzed to produce sugars which have been then fermented by bacteria (Clostridium acetobutylicum) to produce acetone and butanol. This type of bacteria presents an interesting biological platform: it is resilient, easily up-scalable and Clostridium can be genetically engineered to target various other chemicals. Pyrolysis of cellulose was performed in a continuous fluidized bed reactor equipped with a staged condensation system, including a warm electrostatic precipitator. Different bio-oil fractions rich in levoglucosan (LVG) and with different concentrations in inhibitors for the fermentation stage were produced. LVG was found to be nonfermentable by C. acetobutylicum. Therefore, the bio-oil fractions were hydrolysed to obtain fermentable glucose. The mechanisms of acid hydrolysis (with diluted H2SO4) of LVG and cellobiosan have been revealed by high resolution mass spectrometry. The microorganisms were not able to grow with all hydrolysed bio-oil fractions depending on the concentration in inhibitors (aldehydes and organic acids). The fractions rich in LVG (and then glucose) lead to normal bacterial growth and normal fermentation products pattern without the need of detoxification. These results show the importance of a pyrolysis process with a staged condensation as a preliminary step for fermentation. It opens the road to production of various cellulose-derived chemicals by bacteria.

Conversion of Pyrolysis Products into Volatile Fatty Acids with a Biochar-Packed Anaerobic Bioreactor

“…, di or tri-hydroxybenzenes), anhydro-oligosaccharides formed by cellulose ejection, humin-like matter, and hybrid oligomers formed by lignin and cellulose. − WS is bioavailable and partially biodegradable, , and selected fractions of WS ( e.g. , AS and VFA) were successfully converted with HTB schemes by several authors. − Whole WS can be converted to methane by anaerobic digestion in 55–76% yield, , and healthy microbial consortia can degrade most of the GC–MS detectable portion of WS. − …”

Hydrolysis of Anhydrosugars over a Solid Acid Catalyst for Saccharification of Cellulose via Pyrolysis

“…There have been studies that reported performance and kinetics of LGA hydrolysis, the most of which employed homogeneous reaction system with mineral acids or enzymes as the catalyst. [15,16] However, the use of homogeneous catalyst often suffers from problems such as separation of catalyst from the product liquid, the catalyst recyclability, corrosion of reactor materials, and treatment of waste stream. Recently, Abdilla-Santes et al [17] reported that an acidic resin was available as the heterogeneous catalyst for the hydrolysis of LGA.…”