Lignin as a renewable aromatic resource for the chemical industry

Valorization of lignin plays a key role in the further development of lignocellulosic biorefinery processes for biofuels and biobased materials production. Today’s increased demand for alternatives to fossil carbon-based products expands the interest and the need to create added value to the unconverted lignin fraction. The aim of the research was to study the potential of lignin to become a renewable aromatic resource for the chemical industry. Lignin can be considered as an abundantly available and cheap raw material for the manufacturing of an array of products. Development of applications needs to go hand in hand with the anticipated increased production of technical lignins derived from the pulp and paper industry and the emerging lignocellulosic biorefinery industry. Two promising lignin applications are studied in this thesis: 1) the use of lignin in wood adhesives 2) the use of lignin for the production of aromatic chemicals PCA modeling was performed aimed at the prediction of the application potential of different technical lignins for wood adhesive production. The lignins and their fractions could be classified in different clusters based on their structure dependent properties. Lignins exhibiting sufficient reactive sites, medium molar mass and low level of impurities are most promising candidates for the development of lignin based wood adhesives. Both lignin reactivity and formaldehyde-free crosslinking agents are needed to develop emission-free adhesives. Periodate oxidation was studied as method to improve the lignin reactivity. Alternatives to formaldehyde- based glues are under investigation and a combination of lignin and furans might be an interesting concept to develop renewable adhesives. In this research a reliable SEC methodology was developed for the analysis of the molar mass distribution of a wide range of different lignins. The major drawback of this method is that the molar masses are calculated on a relative basis to sulfonated polystyrenes. Using MALDI-TOF-MS and prior fractionation of lignin did not solve all problems associated with the determination of the absolute molar mass of lignin. Supercritical depolymerisation of lignin using a carbon dioxide/acetone/water fluid resulted in a depolymerised lignin oil. In this oil some monomeric compounds are present in relatively high amounts up to 3.6% (based on dry lignin). These products maybe further isolated by downstream processing to obtain purified fine chemicals. For continuous operation of this supercritical process, the formation of char should be further limited. The results presented in this thesis are expected to contribute - together with the many on-going activities worldwide - to the increased commercial utilisation of lignin in the future. Moreover, the obtained results contribute to the increasing knowledge on lignin analysis, chemistry and reactivity. </p

Valorisation of lignin – Achievements of the LignoValue project

Lignocellulosic biorefinery for production of biofuels, materials and chemicals requires valorization of all fractions including lignin. As a consequence of its poly-aromatic structure, lignin potentially serves as a source for aromatic chemicals. The developed biorefinery concept of the LignoValue project comprises two major steps: (1) Organosolv fractionation of wheat straw and willow into (hemi)cellulose and high purity lignin. (2) Further conversion of the isolated lignin via catalytic pyrolysis, supercritical depolymerization and partial hydrodeoxygenation (HDO) into different components like low molecular phenolic compounds, wood adhesives and fuel additives. The cellulose fraction resulting after organosolv fractionation is effectively hydrolysed by enzymes for biofuel production. Quality assessment of the liberated lignins shows interesting characteristics for follow-up chemistry such as high purity, relatively low molar mass and polydispersity. Catalytic pyrolysis in a fluidised bed at 400-500°C was found to convert organosolv lignin in 35-55% phenolic oil, 10% identified monomeric phenolic compounds, 10-20% water, 5-20% gas and 35-55% char. Supercritical depolymerisation of lignin in carbon dioxide based solvents resulted in a similar spectrum of products, however, at a lower temperature (ca 300°C) but at higher pressures. In both thermochemical processes the use of promotors or catalysts lead to an improved yield of the target monomeric aromatic products. Also the residual char fraction shows interesting properties for use in bio-char applications. Catalytic semi-continuous HDO of lignin in hydrogen atmosphere can be manipulated to yield both light oils or heavy oils as potential additives to fuels. Suitable catalysts were found to convert depolymerised lignin to phenolic oils in high yields. In this process no char formation is observed. The lignin oils were successfully tested on lab scale as partial substitution of phenol in resins for gluing wood panels. The LignoValue concept is critically reviewed in a techno-economic analysis demonstrating the potential for further commercial development and adoptation of this innovative biorefinery process in Europe

Biofuel production from acid-impregnated willow and switchgrass

As part of a broader technical and economic feasibility study, we studied production of bioethanol from two types of lignocellulosic biomass by way of concentrated acid impregnation at low temperature. Willow chips and switchgrass were submitted to various impregnation techniques with concentrated sulfuric acid at varying acid: biomass ratios and impregnation times. Goal of the experiments was to investigate the technical feasibility of concentrated acid pretreatment technology as part of an industrial process that employs recycling of acid through biological means. Experimental results showed that significant amounts of fermentable sugars including glucose (up to 78 f max. obtainable glucose) and xylose can be obtained by relatively simple impregnation techniques at room temperature. Fermentation of willow-derived hydrolysates with S. Cerevisiae yielded 0.45 - 0.49 g ethanol/g glucose. Ethanol production rates however were 38 ower compared to standard glucose fermentation, prompting the need for further optimization to reduce the formation of acetic acid and furfural, two fermentation inhibitors. Novel impregnation techniques, including employment of sulfur trioxide, were also investigated but require more work to assess technical feasibilit

Lignin-based bio-asphalt

The present invention relates to a composition comprising bitumen; optionally vegetable oil or derivative thereof; and a lignin preparation, wherein the lignin preparation is characterized by a lignin purity of 60-100 wt.% with respect to the weight of the lignin preparation; and a lignin average molecular weight of 1000-5000 g/mol. The composition may be an asphalt binder composition or asphalt composition. Accordingly, the present invention also relates to a paving or roofing comprising the composition of the invention.Further, the present invention relates to a method of preparing an asphalt composition, comprising mixing bitumen with filler material, adding lignin preparation and vegetable oil to the mixture obtained, preferably wherein the lignin preparation and the vegetable oil are added simultaneously

Lignin-based bio-asphalt

The present invention relates to a composition comprising bitumen; optionally vegetable oil or derivative thereof; and a lignin preparation, wherein the lignin preparation is characterized by a lignin purity of 60-100 wt.% with respect to the weight of the lignin preparation; and a lignin average molecular weight of 1000-5000 g/mol. The composition may be an asphalt binder composition or asphalt composition. Accordingly, the present invention also relates to a paving or roofing comprising the composition of the invention.Further, the present invention relates to a method of preparing an asphalt composition, comprising mixing bitumen with filler material, adding lignin preparation and vegetable oil to the mixture obtained, preferably wherein the lignin preparation and the vegetable oil are added simultaneously

Doodzonde om op te stoken. Lignine de grondstof van de toekomst

Onhandelbaar, wee barstig en recalcitrant. Zo staat het houtpolymeer lignine bekend. Maar de stof vervangt steeds vaker fenol. En onderzoekers zijn hoopvol over de ontwikkeling van bio-BTX en koolstofvezels uit lignine

LigniFAME Public Final report

In this project the whole value chain starting from major producers of biomass side-streams (ADM), external suppliers of lignin-rich bamboo and softwood bark (from paper industry) via partners active in conversion and downstream processing of lignin fractions (FeyeCon, FBR, ECN, Progression Industry) to partners active in producing and marketing (end)products, energy, energy carriers, chemicals materials (Essent, ADM, Soprema, Maersk via Progression Industry) was covere