In a manner similar to crude oil, technical lignins need refining if their potential as reactive polyphenols of well-defined molecular weight polymers and oligomers is to be actualized. In this ...paper, we demonstrate that a continuum of narrow fractions can be isolated by the incremental addition of a nonpolar solvent (hexanes) in a polar (acetone) solution of softwood wood kraft lignin. Three distinct commercial samples of softwood kraft lignin were used to examine the validity of the developed protocol using detailed chromatographic and quantitative functional group analytical methods. It was shown that all samples contain a common relatively monodisperse fraction of a polyphenolic material that can be isolated from the different lignins in yields ranging between 10 and 20% w/w. The versatility of the developed fractional precipitation protocol was further validated by creating artificial physical mixtures of the examined lignins in different proportions and isolating from them precisely calculated fractions of nearly identical molecular weight distributions and composition. Overall, the fractional precipitation approach described here offers the possibility that representative specific narrow fractions, common to a variety of softwood kraft lignins, can be isolated irrespective of the manufacturing details of the pulping process. As such, the otherwise known heterogeneous kraft lignin material, whose composition is relatively unpredictable due to manufacturing variations in making pulp, may now offer consistently homogeneous lignin streams with significant commercial ramifications.
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•Optimized first of two-stage process to jet fuel-range hydrocarbons from lignin.•Three well-characterized technical lignins depolymerized using three customized catalysts.•Ru ...suppressed coking and promoted hydrogenolysis of pine kraft lignin compared to Co.•Sweetgum biorefinery lignin efficiently fragmented over dual acid-base catalyst.•Ru-Zn converted 79% hardwood kraft lignin to oligomers ideal for hydrotreatment.
One-pot conversion of technical lignins to jet fuel is limited by recondensation of unstable intermediates. A two-stage process that first generates stabilized fragments by reductive depolymerization, then upgrades oligomers to hydrocarbons may increase yield. Insights into factors affecting initial depolymerization of industrially relevant lignins were revealed, whereas many studies have focused on upgrading bio-oil or model compounds. Feedstocks, catalysts, and process conditions were varied to identify effects on product composition. Hydrogen and temperature synergistically suppressed coking during pine kraft depolymerization to increase monomer production. Ruthenium was more effective than cobalt at limiting solid residue and improving liquid product yield by promoting hydrogenation and hydrogenolysis. Besides ruthenium, a strong acid-base catalyst effectively deconstructed hardwood biorefinery lignin, targeting alkyl-aryl ether bonds. Ruthenium and zinc converted hardwood kraft lignin to oligomers most suitable for upgrading to jet fuel-range hydrocarbons based on yield (79 % on dry lignin), weight-average molecular weight (1290 g/mol), and chemical structure.
The objective of this study was to evaluate the possibility of producing dissolving grade pulp from tobacco stalk through combining SO2-ethanol-water (SEW) fractionation, alkaline extraction, and ...bleaching with oxygen (O), chlorine dioxide (D), alkaline extraction with hydrogen peroxide (Ep), and hydrogen peroxide (P) (OD0(Ep)D1P). The results showed that the optimum SEW cooking condition to remove the original xylan and lignin in tobacco stalk to an acceptable level was 6% SO2 charge (by weight) at 135 °C for 180 min. A bleachable pulp (Kappa number of 21.5) was produced from the SEW-treated tobacco stalk via a subsequent 1% NaOH extraction. After the OD0(Ep)D1P sequence bleaching, the bleached pulp showed a high brightness (88.1% ISO) and a high α-cellulose content (94.9%). The viscosity (15.8 cP) and the residual xylan content (4.4%) of the pulp were within acceptable levels for dissolving pulp production. Thus, tobacco stalk was shown to be a viable raw material for dissolving pulp production following a SEW treatment, alkaline extraction, and a conventional bleaching sequence.
The domestication of forest trees for a more sustainable fiber bioeconomy has long been hindered by the complexity and plasticity of lignin, a biopolymer in wood that is recalcitrant to chemical and ...enzymatic degradation. Here, we show that multiplex CRISPR editing enables precise woody feedstock design for combinatorial improvement of lignin composition and wood properties. By assessing every possible combination of 69,123 multigenic editing strategies for 21 lignin biosynthesis genes, we deduced seven different genome editing strategies targeting the concurrent alteration of up to six genes and produced 174 edited poplar variants. CRISPR editing increased the wood carbohydrate-to-lignin ratio up to 228% that of wild type, leading to more-efficient fiber pulping. The edited wood alleviates a major fiber-production bottleneck regardless of changes in tree growth rate and could bring unprecedented operational efficiencies, bioeconomic opportunities, and environmental benefits.
Kraft lignin as an emerging renewable feedstock can be used to produce fuels, chemicals, and materials. Hardwood kraft lignin bears intrinsic variation due to wood species and the isolation process. ...The structure and property variation of hardwood kraft lignin could introduce new challenges and opportunities for its application. To better understand such variation, seven kraft lignin samples, originated from southern mixed hardwood (North America), northern mixed hardwood (North America), and Asian mixed hardwood, were isolated from commercial kraft pulping black liquor using both LignoBoost and LignoForce processes. Modern analytical techniques were used to elucidate the characteristics of mixed hardwood kraft lignins, including chemical composition, molecular weight, functional groups, and thermal properties. All lignin samples had a lignin content over 90% (92% to 96%) with one exception, which was northern mixed hardwood kraft lignin with 86% of lignin content and 6% polysaccharides. The elemental and methoxy analyses revealed the expected variation of hardwood kraft lignins with the methoxy content ranging from 0.85 to 1.20 per C9 unit. The weight average molecular weight exhibited a higher variation (from 4800 to 1895 Da) with a descending order of southern mixed hardwood kraft lignins, northern mixed hardwood lignins, and Asian mixed hardwood lignins. The aliphatic hydroxy groups ranged from 14 to 25 per 100 C9 units, and phenolic hydroxy groups ranged from 65 to 112 per 100 C9 units. The catecholic group content ranged from 12 to 34 per 100 C9 units, which is higher than softwood kraft lignin. The lignins isolated from the rapid displacement heating (RDH) pulping process were more condensed than from the regular kraft pulping process. 2D HSQC and quantitative
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C NMR revealed the drastic structure change upon kraft pulp with the low abundance of native lignin linkages and formation of new interunit linkages, such as stilbene, enol ethers, and 1-1'/5'. The S/G ratio was calculated using 2D HSQC spectra correcting for signal shift caused by the catecholic groups.
A soluble perylene monoanhydride diester has been designed and synthesized. It was successfully utilized as an efficient intermediate for the synthesis of the first unsymmetric perylene ...tetracarboxylic tetraester and a series of unsymmetric perylene diester monoimides in good to excellent yields. Its application in synthesis of unsymmetric perylene diimides was also demonstrated. Availability of such a versatile intermediate would enable the convenient integration of perylene tetracarboxylic tetraesters and perylene biester monoimides into intricate functional molecular systems.
Well stacked: A liquid‐crystalline material with crystalline π stacks has been synthesized in which the room‐temperature liquid‐crystalline phase consists of alternating 2D‐crystalline mesogen layers ...and liquidlike alkyl layers. A long‐range ordered layer structure forms as a consequence of the resulting microsegregation (see picture), with the π stacks contributing to the 2D crystalline order that exists within a layer.
A facile synthesis of chiral unsymmetric perylene tetracarboxylic diimides (PDIs) has been developed and the first two nonracemic chiral amphiphilic PDIs have been synthesized. The key building ...blocks, AB bifunctional 3,4,9,10-perylenetetracarboxylic-3,4-anhydride-9,10-imides, were prepared conveniently from enantiomerically pure α-amino acids, which were introduced as the steric and stereochemical controlling units. Such building blocks allow the incorporation of sterically and stereochemically controlled PDI moieties into both terminal and inner positions.
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