Jean-Michel Lavoie

Conversion of lignin to aromatic-based chemicals (L-chems) and biofuels (L-fuels)

Conversion of lignin into chemicals and biofuels was performed using the commercial Kraft lignin, Indulin AT. Lignin was depolymerised in an aqueous alkaline solution using a continuous flow reactor generating four fractions. First is the gas fraction (mainly CO(2)), the second includes methanol, acetic acid and formic acid, thus defined as small organic compounds and third one (up to 19.1 wt.% of lignin) is mostly composed of aromatic monomers. The fourth fraction (45-70 wt.%) contains oligomers (polyaromatic molecules) and modified lignin. Pyrocatechol was the most abundant product at high severities (315°C) with selectivity up to 25.8%. (31)P NMR showed the loss of almost all aliphatic OH groups and apparition of catechol groups during depolymerisation.

Review on dry reforming of methane, a potentially more environmentally-friendly approach to the increasing natural gas exploitation

With the actual growth of the natural gas industry in the US as well as the potential and availability of this non-renewable carbon source worldwide, reforming of methane gas is getting increasing attention. Methane can be used for the production of heat or electricity, as well, it can be converted to syngas, a building block that could lead to the production of liquid fuels and chemicals, a very promising pathway in light of the increasing price of oil. Amongst the different reforming techniques, dry reforming could represent a very interesting approach both to valorize a cheap source or carbon (CO2) as well as to reduce the overall carbon footprint of the increasing worldwide fossil-based methane consumption. In this short review, attention will be given to the thermodynamics of dry reforming followed by an investigation on dry reforming using heterogeneous catalyst by focusing on the most popular elements used in literature for dry reforming. Attention will as well be given to other emerging techniques that may allow countering at one point the high thermodynamic penalties that accompanies conversion of methane using carbon dioxide.

Depolymerization of steam-treated lignin for the production of green chemicals

In this short communication, lignin produced by steam processing of agricultural (hemp) and forestry (softwood) was depolymerised via a base catalysis to produce a combination of monomers, dimers, trimers and residual char. The lignin broth produced directly after the base-catalysed steam treatment was treated under pressure (from 1300 to 1900 psi) at temperatures varying from 300 to 330 °C in a custom-made batch reactor. The lignin concentration in the aqueous base solution was 10 wt% whilst the NaOH concentration was 5 wt%. Identification of 26 compounds has been done: 17 compounds were common to the two feedstocks while the remaining 9 were specific to each feedstock used.

Production of pulp from Salix viminalis energy crops using the FIRSST process

In this work, isolation of the cellulose fibres was carried out via the Feedstock Impregnation Rapid and Sequential Steam Treatment process (FIRSST). The latter allows the separation of extractives, hemicellulosic sugars and lignin isolating the cellulose fibres. Quantitative data on the constitutive macromolecules of biomass was obtained using ASTM or TAPPI standard methods. Carbohydrates found in the hemicelluloses were also quantified using HPLC. Kraft pulp from whole biomass has also been produced at a bench scale (few kg per batch) using known and established pulping conditions. The pulps from both pulping techniques were tested following ATTPC standard methods. Pulp yields were of 34% for the classical Kraft processes (using whole biomass) while the FIRSST process showed yields around 30%. The average fibre lengths were similar for FIRSST pulp (0.39 mm) and Kraft pulp (0.41 mm) and the mechanical properties of the FIRSST pulp were as good as those of the Kraft pulp.

UV-Vis as quantification tool for solubilized lignin following a single-shot steam process.

In this short communication, UV/Vis was used as an analytical tool for the quantification of lignin concentrations in aqueous mediums. A significant correlation was determined between absorbance and concentration of lignin in solution. For this study, lignin was produced from different types of biomasses (willow, aspen, softwood, canary grass and hemp) using steam processes. Quantification was performed at 212, 225, 237, 270, 280 and 287 nm. UV-Vis quantification of lignin was found suitable for different types of biomass making this a timesaving analytical system that could lead to uses as Process Analytical Tool (PAT) in biorefineries utilizing steam processes or comparable approaches.

Yield and composition of lipophylic extracts of yellow birch (Betula alleghaniensis Britton) as a function of wood age and aging under industrial conditions

Abstract The lipophylic extracts of yellow birch (Betula alleghaniensis) have been investigated to detect the effect of tree age and wood storage time on extract composition. A total of 17 wood disks were cut from trees belonging to different age groups at 1 m above ground and the wood was milled as usual for extraction (laboratory samples). In addition, 49 sawdust samples were collected in a lumber mill to study the effect of industrial processing on the extractives (industrial samples). All laboratory and industrial samples were extracted with dichloromethane under sonication. The chemical composition of the lipophilic extracts obtained was analyzed by GC-MS. A systematic (quasi-linear) relationship was found between the lipophilic extract yield and specimen age. A total of 30 constituents from yellow birch extracts have been identified, 26 of which have never been previously reported for B. alleghaniensis wood.

Dry reforming of methane with CO2 on an electron-activated iron catalytic bed.

A preliminary experimental investigation of dry reforming of methane with carbon dioxide, that has been performed on an iron bed activated with an electric current is reported. Operating conditions for the reaction included temperature ranging from 700 to 800° C and pressure close to 1 atm. The reaction, involving an excess of pure methane and carbon dioxide, was performed with and without addition of water vapour, provided by hot water saturation of the gaseous feed. According to syngas compositions, the electron flow has a dramatic effect on the conversion of both methane and carbon dioxide. It was shown also that hot water saturation of the CO(2) and CH(4) mixture allowed very good conversion, giving a syngas with a composition very close to what was expected from equilibrium calculations.

Biorefining Lignocellulosic Biomass via the Feedstock Impregnation Rapid and Sequential Steam Treatment

The first generation of biofuels, made out of starch (ethanol) or triacyglycerol (biodiesel) uses expensive homogeneous feedstocks (sugar cane, corn, wheat and edible oils) coupled with relatively inexpensive technologies known and practiced for years at an industrial level. First generation biofuels have had a bad press: high water and energy consumption (very significant is the energy used in the production of the fertilizers needed by agriculture) and the fuel versus food controversy. Increased use of biofuels requires alternative sources of biomass that lower water and energy consumption and do not compete with food supplies. Lignocellulosic biomass, either from forestry or agriculture offers such potential. Cellulose, the most abundant carbohydrate on the planet, is a fraction of the complex lignocellulosic matrix along with other macromolecules, lignin, hemicelluloses, and extractives. The cellulose macromolecule is composed of glucose units linked together via ┚-1,4-glycosidic bonds (or acetal bonds) creating long chains that combine together to form fibrils and eventually fibres. The polar hydroxyl groups are oriented one toward the other so that interaction with a polar medium (as a solvent) is fairly difficult making cellulose water resistant. The natural macromolecule is usually present in nature in two forms: crystalline and amorphous. A typical fibril will have zones that are crystalline separated by zones that are amorphous. Whilst the crystalline form is difficult to disassemble with hydrolyzing agents, the amorphous phase has a certain level of disorder that makes relatively easy the penetration and action of hydrolysing agents, either enzymes or ionic species. The other macromolecules found in the lignocellulosic matrix are also of interest. Lignin is a macromolecule composed of phenylpropane units bond together via, predominantly, ether bonds although C-C between moieties are also significant. Lignin, has low oxygen content and thus a high energetic value. Hemicelluloses are, as cellulose, macromolecules composed of carbohydrates. Upon hydrolysis, the C6 fraction of these carbohydrates can effectively be converted to ethanol via fermentation using classical yeast strands (Girio, 2009). Studies have shown that fermentation of all the glucidic part of the hemicelluloses, both C6 and C5 sugars, was feasible using nontraditional microorganisms (Agbogbo & Coward-Kelly, 2008; Casey et al., 2009; Chu & Lee, 2007). It is also well known

Structural changes of Salix miyabeana cellulose fibres during dilute-acid steam explosion: Impact of reaction temperature and retention time

Dilute-acid steam explosion of Salix miyabeana has been carried out to understand the effect of processing conditions, expressed through a severity factors (SFT), on the changes in cellulose fibre structures in a perspective of using these in polymer composites. This thermo-chemico-mechanical extraction leads to the isolation of cellulose fibres as observed by SEM images. Fibre length as well as length to diameter aspect ratios decreased with the severity of the treatment. Likewise, fibre whiteness diminished with an increasing severity factor, which could be a tangible effect of physical degradation. Variations in crystallinity seemed to be dependent upon the reaction temperature, generally decreasing with regards to retention time. Above a severity threshold, a structural disorganization was observed. Overall, dilute-acid steam explosion was shown to be a valuable cellulose extraction process that can provide a variety of fibre structures.

Biofuels and Co-Products Out of Hemicelluloses

Second generation biofuels are based on the utilisation of non-edible feedstock for the production either of ethanol to be inserted in the gasoline pool or of biodiesel to be insert‐ ed in the diesel pool. Ethanol is usually produced out of fermentation of C6 sugars (al‐ though other approaches does exist, see [1]) and the latter came, in first generation ethanol, from starch. In second-generation ethanol, the source of carbohydrate considered is usually cellulose, which, in turns, is obtained from lignocellulosic biomass. Recent work by Lavoieet al. [2] have depicted an overview of many types of lignocellulosic biomass and in most cases, cellulose, although a major component, is not the only one and is ac‐ companied by lignin, hemicelluloses, extractives and, in case of agricultural biomass, pro‐ teins. High grade biomass (as wood chips, sugar cane or even corn) are usually very expensive (more than 100 USD/tonne) because, in most part, of the important demand re‐ lated to those feedstock in industries and this is why cellulosic ethanol is more than often related to residual biomass. The latter includes but is not limited to residual forest and ag‐ ricultural biomass as well as energy crops. In all cases, although the feedstock is rather in‐ expensive (60-80 USD/tonne), it is composed of many different tissues (leaves, bark, wood, stems, etc.) making its transformation rather complex [3]. Industrialisation of second-gen‐ eration biofuel requires specific pre-treatment that should be as versatile as efficient in or‐ der to cope with the economy of scale that has to be implemented in order to make such conversion economical.