Biomass Conversion

Lignin is the largest renewable source of aromatic chemical building blocks on the planet and has great potential for the production of value-added chemicals. Herein, we describe lignin hydrogenolysis/depolymerization of organosolv poplar lignin (OPL) in ethanol/isopropanol solvent in the absence of added catalysts. Different EtOH/i-PrOH ratios as well as various reaction conditions were evaluated. OPL depolymerization was more effective in the mixed media than in ethanol or isopropanol alone. Heating OPL at 270°C for 4 h in 50:50 (v:v) EtOH/i-PrOH in a closed pressure vessel gave an overall oil yield of 70 wt %, of which about 48% consisted of the monomers (E)-4-propenyl syringol and isoeugenol. Notably, these catalyst-free reactions in ethanol/ isopropanol media show monomer yields comparable to those reported for lignin depolymerization using precious metal catalysts and dihydrogen, which suggests unexpectedly favorable H-donor ability of this mixed alcohol medium.

Development of a competent method for the conversion of hemicellulose, a lignocellulosic component, into sugars is essential. In a one-pot method, Brönsted acidic ionic liquid (BAIL)-catalyzed hydrolysis of hardwood hemicellulose at 160 °C in water media gave C5 sugars (xylose + arabinose) in 87% yield. The efficiency of the ILs and their acid strength both followed the similar trend, ijC 3 SO 3 HMIM]ijHSO 4 ] > [C 3 SO 3 HMIM][PTS] > [C 3 SO 3 HMIM][Cl] > [BMIM][Cl]. The ion–dipole-type interaction present between the BAIL and the substrate, which is proposed by the 1 H NMR study, is suggested to help in achieving better activity with BAIL than with mineral acid, H 2 SO 4 .

... Veronika Wilk & Hannes Kitzler & Stefan Koppatz & Christoph Pfeifer & Hermann Hofbauer ... In: Proceedings of the 18th European Biomass Conference and Exhibition, France 8. Pröll T, Hofbauer H (2008) H2 rich syngas by selective CO2 removal from biomass gasification in a ...

There are two types of processive cellulases, exocellulases and processive endoglucanases. There are also two classes of exocellulases, ones that attack the reducing ends of cellulose chains and ones that attack the nonreducing ends. There are a number of ways of assaying processivity but none of them are ideal. It appears that exocellulases, all of which have their active sites in a tunnel, couple movement along a cellulose chain with cleavage of cellobiose from the end of the cellulose molecule. There are two sets of structures that suggest how an exocellulase might move along a cellulose chain. For family 48 exocellulases there are two different ways that a chain can be bound in the active site while for family 6 exocellulases there are several different ligand-bound structures. Site-directed mutagenesis of Thermobifida fusca exocellulases Cel48A and Cel6B and the processive endoglucanase Cel9A have identified some mutations that increase processivity and some that decrease processivity. In addition a mutation in Cel6B was identified that appears to allow the mutant enzyme to move along a cellulose chain in the absence of cleavage.

The native complexity of plant cell walls makes research on them challenging. Hence, it is advantageous to have a diversity of tools that can be used to analyze and characterize plant cell walls. In this chapter, we describe one of two immunological approaches that can be employed for screening of plant cell wall/biomass materials from diverse plants and tissues. This approach, Glycome Profiling, lends itself well to moderate to high-throughput screening of plant cell wall/biomass samples. Glycome Profiling is being further optimized to reduce the amount of sample required for the analysis, and to improve the sensitivity and throughput of the assay. We are optimistic that Glycome Profiling will prove to be a broadly applicable experimental approach that will find increasing application to a wide variety of studies on plant cell wall/biomass samples.