Thermal and Mechanical Properties of Esterified Lignin in Various Polymer Blends.

Lignin is an abundant polymeric renewable material and thus a promising candidate for incorporation in various commercial thermoplastic polymers. One challenge is to increase the dispersibility of amphiphilic lignin in lipophilic thermoplastic polymers We altered Kraft lignin using widely available and renewable fatty acids, such as oleic acid, yielding more than 8 kg of lignin ester as a light brown powder. SEC showed a molecular weight of 5.8 kDa with a PDI = 3.80, while the Tg of the lignin ester was concluded to 70 °C. Furthermore, the lignin ester was incorporated (20%) into PLA, HDPE, and PP to establish the thermal and mechanical behavior of the blends. DSC and rheological measurements suggest that the lignin ester blends consist of a phase-separated system. The results demonstrate how esterification of lignin allows dispersion in all the evaluated thermoplastic polymers maintaining, to a large extent, the tensile properties of the original material. The impact strength of HDPE and PLA blends show substantial loss upon the addition of the lignin ester. Reconverting the acetic acid side stream into acetic anhydride and reusing the catalyst, the presented methodology can be scaled up to produce a lignin-based substitute to fossil materials.

Enantio- and Regioselective Ir-Catalyzed Hydrogenation of Di- and Trisubstituted Cycloalkenes.

A number of cyclic olefins were prepared and evaluated for the asymmetric hydrogenation reaction using novel N,P-ligated iridium imidazole-based catalysts (Crabtree type). The diversity of these cyclic olefins spanned those having little functionality to others bearing strongly coordinating substituents and heterocycles. Excellent enantioselectivities were observed both for substrates having little functionality (up to >99% ee) and for substrates possessing functional groups several carbons away from the olefin. Substrates having functionalities such as carboxyl groups, alcohols, or heterocycles in the vicinity of the C═C bond were hydrogenated in high enantiomeric excess (up to >99% ee). The hydrogenation was also found to be regioselective, and by controlling the reaction conditions, selective hydrogenation of one of two trisubstituted olefins can be achieved. Furthermore, trisubstituted olefins can be selectively hydrogenated in the presence of tetrasubstituted olefins.

Debottlenecking a Pulp Mill by Producing Biofuels from Black Liquor in Three Steps.

By extracting lignin, pulp production can be increased without heavy investments in a new recovery boiler, the typical bottleneck of a pulp mill. The extraction is performed by using 0.20 and 0.15 weight equivalents of CO2 and H2 SO4 respectively. Herein, we describe lignin esterification with fatty acids using benign reagents to generate a lignin ester mixable with gas oils. The esterification is accomplished by activating the fatty acid and lignin with acetic anhydride which can be regenerated from the acetic acid recycled in this reaction. The resulting mass balance ratio is fatty acid/lignin/acetic acid (2 : 1 : 0.1). This lignin ester can be hydroprocessed to generate hydrocarbons in gasoline, aviation, and diesel range. A 300-hour continuous production of fuel was accomplished. By recirculating reagents from both the esterification step and applying a water gas shift reaction on off-gases from the hydroprocessing, a favorable overall mass balance is realized.

High Yields of Bio Oils from Hydrothermal Processing of Thin Black Liquor without the Use of Catalysts or Capping Agents.

Black liquor (BL) from the kraft pulping process has been treated at elevated temperatures (380 °C) in a batch reactor to give high yields of a bio oil comprising monomeric phenolic compounds that were soluble in organic solvents and mineral oil and a water fraction with inorganic salts. The metal content in the product was <20 ppm after a simple extraction step. A correlation between concentration, temperature, and reaction time with respect to yield of desired product was found. At optimal reaction conditions (treating BL with 16 wt % dry substance at 380 °C for 20 min), the yield of extractable organics was around 80% of the original lignin with less than 7% of char. The product was analyzed by gel permeable chromatography, mass spectroscopy, nuclear magnetic resonance, elemental analysis, and inductively coupled plasma. It was found that a large fraction composed of mainly cresols, xylenols, and mesitols. This process provides a pathway to convert a major waste stream from a pulp mill into a refinery feed for fuel or chemical production, whereas at the same time the inorganic chemicals are recovered and can be returned back to the pulp mill.

Green Diesel from Kraft Lignin in Three Steps.

Precipitated kraft lignin from black liquor was converted into green diesel in three steps. A mild Ni-catalyzed transfer hydrogenation/hydrogenolysis using 2-propanol generated a lignin residue in which the ethers, carbonyls, and olefins were reduced. An organocatalyzed esterification of the lignin residue with an in situ prepared tall oil fatty acid anhydride gave an esterified lignin residue that was soluble in light gas oil. The esterified lignin residue was coprocessed with light gas oil in a continous hydrotreater to produce a green diesel. This approach will enable the development of new techniques to process commercial lignin in existing oil refinery infrastructures to standardized transportation fuels in the future.