Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “AROMATICS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Controlling Tautomerization in Pyridine-Fused Phosphorus-Nitrogen Heterocycles

Inclusion of a second nitrogen atom in the aromatic core of phosphorus-nitrogen (PN) heterocycles results in unexpected tautomerization to a nonaromatic form. This tautomerization, initially observed in the solid state through X-ray crystallography, is also explained by computational analysis. We prepared an electron deficient analogue (2 e) with a fluorine on the pyridine ring and showed that the weakly basic pyridine resisted tautomerization, providing key insights to why the transformation occurs. To study the difference in solution vs. solid-state heterocycles, alkylated analogues that lock in the quinoidal tautomer were synthesized and their different 1 H NMR and UV/Vis spectra studied. Ultimately, we determined that all heterocycles are the aromatic tautomer in solution and all but 2 e switch to the quinoidal tautomer in the solid state. Better understanding of this transformation and under what circumstances it occurs suggest future use in a switchable on/off hydrogen-bond-directed receptor that can be tuned for complementary hydrogen bonding.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Production of Jet Fuel-Range Hydrocarbons from Hydrodeoxygenation of Lignin over Super Lewis Acid Combined with Metal Catalysts

Super Lewis acids containing the triflate anion (e.g. Hf(OTf)4, Ln(OTf)3, Al(OTf)3) and noble metal catalysts (e.g. Ru/C, Ru/Al2O3) formed efficient catalytic systems to generate saturated hydrocarbons from lignin in high yields. In such catalytic systems, the metal triflates mediated rapid ether bond cleavage via selective bonding to etheric oxygens while the noble metal catalysed subsequent hydrodeoxygenation (HDO) reactions. Near theoretical yields of hydrocarbons were produced from lignin model compounds by the combined catalysis of Hf(OTf)4 and ruthenium-based catalysts. When a technical lignin derived from a pilot-scale biorefinery was used, more than 30 wt% of the hydrocarbons produced with this catalytic system were cyclohexane and alkylcyclohexanes in the jet fuel range. Super Lewis acids are postulated to strongly interact with lignin substrates via protonating hydroxyls and ether linkages, forming intermediate species that enhance hydrogenation catalysis by supported noble metal catalysts. Meanwhile, the hydrogenation of aromatic rings by the noble metal catalysts can promote oxygenation reactions catalysed by super Lewis acids.

Wang, Hongliang↗
DOE OSTI2020

Electrochemical Lignin Conversion

Lignin is the largest source of renewable aromatic compounds, making the recovery of aromatic compounds from this material a significant scientific goal. Recently, many studies have reported on lignin depolymerization and upgrading strategies. Electrochemical approaches are considered to be low cost, reagent free, and environmentally friendly, and can be carried out under mild reaction conditions. Here, different electrochemical lignin conversion strategies, including electrooxidation, electroreduction, hybrid electro-oxidation and reduction, and combinations of electrochemical and other processes (e.g., biological, solar) for lignin depolymerization and upgrading are discussed in detail. In addition to lignin conversion, electrochemical lignin fractionation from biomass and black liquor is also briefly discussed. Finally, the outlook and challenges for electrochemical lignin conversion are presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Hydrogenolysis of Poly(Ethylene–co–Vinyl Alcohol) and Related Polymer Blends over Ruthenium Heterogeneous Catalysts

The hydrogenolysis of polymers is emerging as a promising approach to deconstruct plastic waste into valuable chemicals. Yet, the complexity of plastic waste, including multilayer packaging, is a significant barrier to handling realistic waste streams. Herein, we reveal fundamental insights into a new chemical route for transforming a previously unaddressed fraction of plastic waste – poly(ethylene–co­­–vinyl alcohol) (EVOH) and related polymer blends – into alkane products. Additionally, we report that Ru/ZrO2 is active for the concurrent hydrogenolysis, hydrogenation, and hydrodeoxygenation of EVOH and its thermal degradation products into alkanes (C1–C35) and water. Detailed reaction data, product analysis, and catalyst characterization reveal that the in–situ thermal degradation of EVOH forms aromatic intermediates that are detrimental to catalytic activity. Increased hydrogen pressure promotes hydrogenation of these aromatics, preventing catalyst deactivation and improving alkane product yields. Calculated apparent rates of C–C scission reveal that the hydrogenolysis of EVOH is slower than low–density polyethylene. We apply these findings to achieve hydrogenolysis of EVOH/polyethylene blends and elucidate the sensitivity of hydrogenolysis catalysts to such blends. Overall, we demonstrate progress towards efficient catalytic processes for the hydroconversion of waste multilayer film plastic packaging into valuable products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Density Functional Theory Guided Investigation of Ligand‐Induced Neptunyl‐Neptunyl Interactions

Abstract Actinyl‐actinyl interactions are particularly prevalent for the pentavalent neptunyl cation (Np(V)O 2 ) + where these interactions appear either as a T ‐ or D ‐shape (diamond‐shape). T ‐shaped interactions have been previously identified in high concentration Np(V) solutions containing simple anions (NO 3 − , ClO 4 − , Cl − ) whereas D ‐shaped have only been isolated in the solid‐state in the presence of carboxylate ligands. In this study, Density Functional Theory (DFT) calculations were paired with Raman spectroscopy to evaluate the formation of D ‐shaped interactions in the presence of aliphatic (R=H (formate), CH 3 (acetate), CH 2 CH 3 (propionate)) and aromatic (R=C 6 H 5 (benzoate), C 6 H 4 OH (4‐hydroxybenzoate), C 5 H 4 N (isonicotinate)) carboxylate ligands. DFT studies indicate that the Δ G to form hydrated T ‐ and D ‐shaped forms are not spontaneous but become so with the addition of the carboxylate ligands. Raman spectra of the Np(V) carboxylate solutions contained vibrational modes associated with the D ‐shaped interactions, but spectral changes observed over time indicate a dynamic system. Crystallization experiments from the Np(V) carboxylate systems confirmed the presence of D‐ shaped dimers for the aromatic carboxylates, suggesting that the choice of the anion in solution favors actinyl‐actinyl interactions even at low concentrations (≤20 mM) of Np(V).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

The Reactivity of the Nitrate Radical ( • NO 3 ) in Aqueous and Organic Solutions

In this study, rate constants for the ( • NO 3 ) radical reaction with alcohols, alkanes, alkenes and several aromatic compounds were measured in aqueous and tert-butanol solution for comparison to aqueous and acetonitrile values from the literature. The measured trends provide insight into the reactions of the • NO 3 radical in various media. The reaction with alcohols primarily consists of hydrogen-atom abstraction from the alpha-hydroxy position, and is faster in solvents of lower polarity where the diffusivity of the radical is greater. Alkenes react faster than alkanes, and their rate constants are also faster in non-polar solution. The situation is reversed for nitrate radical reaction with the aromatic compounds, where the rate constants in tert-butanol are slower. This is attributed to the need to solvate the NO 3 - anion and corresponding tropylium cation produced by the • NO 3 radical electron transfer reaction. Finally, a linear correlation was found between measured rate constants in water and acetonitrile, which can be used to estimate aqueous nitrate radical rate constants for compounds having low water solubility.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2020

Formation of phenanthrene via H–assisted isomerization of 2–ethynylbiphenyl produced in the reaction of phenyl with phenylacetylene

Model chemistry G3(MP2,CC)//B3LYP/6–311G(d,p) calculations of the potential energy surface for the reaction of phenyl radical (C 6 H 5 ) with phenylacetylene (C 8 H 6 ) have been carried out and combined with Rice–Ramsperger–Kassel–Marcus/Master Equation calculations of temperature– and pressure–dependent rate constants. The results showed that the reaction can serve as a viable source for the formation of phenanthrene via an indirect route involving a primary reaction of phenyl addition to the ortho carbon in the ring of phenylacetylene and H elimination producing 2–ethynylbiphenyl followed by secondary H–assisted isomerization of 2–ethynylbiphenyl to phenanthrene. In the secondary reaction, the H atom adds to the α carbon of the ethynyl side chain, then a six–member ring closure takes place followed by aromatization via an H loss. The channel of H addition to the side chain of 2–ethynylbiphenyl appears to be much faster than H addition to the ortho carbon in the ethynyl–substituted ring leading back to the initial C 6 H 5 + C 8 H 6 reactants. Rate constants for the primary C 6 H 5 + C 8 H 6 ⇌2–ethynylbiphenyl (p1) + H and secondary p1 + H⇌phenanthrene (p2) + H reactions have been computed in the temperature range of 500–2500 K at pressures of 30 Torr, 1, 10, and 100 atm and fitted to modified Arrhenius expressions. Here, the suggested kinetic scheme and rate constants are proposed as a prototype for the modeling of the growth of polycyclic aromatic hydrocarbons via the phenyl addition–dehydrocyclization (PAC) mechanism involving an addition of a PAH radical to an ethynyl–substituted PAH molecule.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Electron affinity of modified benzene

The electron affinities of organic molecules obeying Hückel's rule of aromaticity are vanishingly small, if not negative. An example is, benzene, a classic example of an aromatic molecule, has an electron affinity of -1.15 eV. Using density functional theory, we have systematically calculated the electron affinities and vertical detachment energies of C 6 H 6 by substituting H with halogen (F) and superhalogen (BO 2 ) moieties, as well as replacing one of the C atoms with B. The ground state geometries were obtained by examining about 330 isomers. The electron affinities are found to steadily increase with these substitutions/replacements, even surpassing that of Cl, the element with the highest electron affinity in the periodic table, in the case of C 5 BH(BO 2 ) 5 . In some special cases such as C 6 H 5 (BO 2 ) the electron affinity and vertical detachment energy differ by as much as 5 eV, indicating substantial changes in the geometry as the electron is removed from the anion. We hope that the ability to change the negative electron affinity of C 6 H 6 to large positive values by substituting H and/or replacing C atom will motivate experimental studies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

2D Nitrogen‐Doped Graphene Materials for Noble Gas Separation

Abstract Noble gases, notably xenon, play a pivotal role in diverse high‐tech applications. However, manufacturing xenon is an inherently challenging task, due to its unique properties and trace abundance in the Earth's atmosphere. Consequently, there is a pressing need for the development of efficient methods for the separation of noble gases. Using mild fluorographene chemistry, nitrogen‐doped graphene (GNs) materials are synthesized with abundant aromatic regions and extensive nitrogen doping within the vacancies and holes of the aromatic lattice. Due to the organized interlayer “nanochannels”, nitrogen functional groups, and defects within the two‐dimensional (2D) structures, GNs exhibits effective selectivity for Xe over Kr at low pressure. This enhanced selectivity is attributed to the stronger binding affinity of Xe to GN compared to Kr. The adsorption is governed by London dispersion forces, as revealed by theoretical calculations using symmetry‐adapted perturbation theory (SAPT). Investigation of other GNs differing in nitrogen content, surface area, and pore sizes underscores the significance of nitrogen functional groups, defects, and interlayer nanochannels over the surface area in achieving superior selectivity. This work offers a new perspective on the design and fabrication of functionalized graphene derivatives, exhibiting superior noble gas storage and separation activity exploitable in gas production technologies.

Šedajová, Veronika↗
DOE OSTI2018

Thermal and Physiochemical Characterization of Lignin Extracted from Wheat Straw by Organosolv Process

The purified lignin extracted from wheat straw by organosolv process was characterized for the existence of lignin subunits, functional groups and physical and thermal behaviours. Presence of carboxyl, hydroxyl, methoxyl groups and C–C, C–O, C=O linkages were conducted by Fourier Transform Infrared (FT-IR). By {sup 1}H-NMR (Nuclear Magnetic Resonance Spectroscopy) presence of aromatic protons, phenolic hydroxyls, carboxylic acids, and aldehydes were established. Moreover, {sup 13}C-NMR spectra have disclosed the presence of condensed and uncondensed aliphatic and aromatic aryls and ethers. The existence of syringyl and guaiacyl units also were confirmed with both FTIR and NMR spectroscopies. Furthermore, the results from Thermal Gravimetric Analysis (TGA) showed the weight of extracted lignin is changed in temperatures between 180 and 670 °C by devolatization, formation and condensation of different chemicals. Also, the Differential Scanning Calorimetry (DSC) graph displayed a glass transition temperature of 105 °C for extracted lignin. As a result, the extracted lignin with high purity can be a suitable candidate for carrying out value-added products.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Quantum chemical study of the structures and dynamic behavior of tricarbonyl complexes of Group 6 metals (Cr, Mo, W) with polyaromatic hydrocarbons using the density functional theory

The quantum chemical study of the mechanism was performed for tricarbonyl η{sup 6}-complexes of coronene I-M and kekulene II-M (M = Cr, Mo, W) by the density functional method. The activation barriers of η{sup 6},η{sup 6}-interring haptotropic rearrangements (IHR), being the migration of the metaltricarbonyl group M(CO){sub 3} from one six-membered aromatic ring to another, were determined. The processes of η{sup 6},η{sup 6}-IHR in the metal tricarbonyl complexes with relatively high polycyclic aromatic hydrocarbons (PAH) I and II occur with close energy barriers (ΔG{sup ≠} ≈ 20—25 kcal mol{sup –1}), which are lower than the barriers (ΔG{sup ≠} ~ 30 kcal mol{sup –1}) of similar transformations measured or calculated earlier for the chromium tricarbonyl complexes of naphthalene and its derivatives and other PAH. For the molybdenum tricarbonyl complexes the activation barriers of η{sup 6},η{sup 6}-IHR decrease additionally by ~ 5 kcal mol{sup –1} compared to those for the chromium tricarbonyl complexes, whereas for the tungsten tricarbonyl complexes they increase again and become approximately equal to the activation barriers of similar chromium tricarbonyl complexes. All stationary states on the potential energy surface determining the mechanism of η{sup 6},η{sup 6}-IHR are characterized by a decrease in hapticity compared to the initial and final complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Corrosion Protection of Phenolic-Epoxy/Tetraglycidyl Metaxylediamine Composite Coatings in a Temperature-Controlled Borax Environment

The failure behavior for two kinds of phenolic-epoxy/tetraglycidyl metaxylediamine composite coatings in 60 °C borax aqueous solution was evaluated using electrochemical methods (EIS) combined with scanning electron microscopy, confocal laser scanning microscope, water immersion test, and Raman spectrum. The main focus was on the effect of curing agent on the corrosion protection of coatings. Results revealed that the coating cured by phenolic modified aromatic amine possessed more compact cross-linked structure, better wet adhesion, lower water absorption (0.064 mg h{sup −1} cm{sup −2}) and its impedance values was closed to 10{sup 8} Ω cm{sup 2} after immersion for 576 h, while the coating cured by modified aromatic ring aliphatic amine was lower than 10{sup 5} Ω cm{sup 2}. The corrosion mechanism of the two coatings is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Fluorinated ionic liquids as gas chromatographic stationary phases for the separation of volatile per- and polyfluoroalkyl substances

Background Here, the production of fluorinated organic compounds in the manufacturing, semiconductor, and pharmaceutical industries has increased exponentially over the past decade. This rapid growth has created an urgent need for efficient chromatographic platforms capable of selectively separating these compounds from complex mixtures, not only to support industrial quality control and waste management practices, but also to enable reliable environmental monitoring of volatile fluorinated contaminants. Conventional GC stationary phases lack the fluorophilic interactions needed for highly fluorinated analytes. Consequently, there is a clear demand for specialized stationary phases designed to improve chromatographic retention and selectivity for these compounds. Results Three stationary phases composed of fluorinated ionic liquids (ILs) with varied extent of fluorination were prepared to study fluorophilic interactions with fluorinated/non-fluorinated probe molecules by gas chromatography (GC). IL stationary phases featuring linear and branched perfluoroalkyl moieties, as well as a branched alkyl moiety, were systematically investigated. Chromatographic performance was examined using fluorinated compounds and their hydrocarbon analogs, including CF 3 -substituted aromatics, aliphatic alcohols, fluorotelomer alcohols (FTOHs), and perfluoroalkenes. Measurements on 5 m and 20 m columns revealed that the IL possessing branched alkyl provided stronger dispersive and hydrogen bonding interactions toward non-fluorinated aromatic and long-chain alcohols, whereas the fluorinated ILs enhanced retention of highly fluorinated FTOHs and perfluorodecene. Comprehensive two-dimensional GC (GC × GC), using a nonpolar primary column coupled with secondary columns featuring cross-bonded poly(trifluoropropylmethyl siloxane) (Rtx-200 ms), the branched fluorinated IL, or the branched non-fluorinated IL, highlighted complementary selectivity with the branched fluorinated IL providing the strongest interactions with fluorinated analytes. Significance These results demonstrate that fluorinated IL stationary phases are promising alternatives to conventional polysiloxane stationary phases for improving the separation of per- and polyfluoroalkyl substances and related fluorinated compounds. By correlating IL structure with fluorophilic interactions, this work establishes design principles for GC stationary phases that enable enhanced selectivity for highly fluorinated analytes while maintaining complementary interactions with non-fluorinated compounds.

Comprehensive two-dimensional GC↗
DOE OSTI2013

Hydroconversion of liquid hydrocarbons in a staged autothermal reactor

An autothermal staged reactor was assembled containing a top stage of Rh-Ce/alpha-Al2O3 which generated heat and H-2 by reacting CH4 and air that passed through a downstream stage containing 0.5 wt% Pt/gamma-Al2O3 mixed with either HBEA, HZSM-5, or USY in a heat-integrated non-isothermal reactor. The H-2 produced subsequently reacts in a 20:1 ratio with a co-feed of hexane or decane or 2-decanone fed to the reactor between the stages. The large-sized pores of HBEA and USY allowed deoxygenation of 2-decanone to form decene isomers which can crack or cyclize to form up to a 36% yield of methylated and ethylated monoaromatics. The medium-sized pores of HZSM-5 restricted decene formation from 2-decanone by catalyzing cracking reactions to C2-6 compounds which can cyclize to form aromatics. By contrast, the reactor effluent from non-oxygenated reactants decane and hexane contained less than 5% aromatics. Thus, we extend the scope of staged autothermal reactor functionality to hydrocracking and hydroisomerization of higher saturated and oxygenated hydrocarbons. (C) 2012 Elsevier B.V. All rights reserved.

Blass, SD↗
DOE OSTI2023

Plant-wide modeling and techno-economic analysis of a direct non-oxidative methane dehydroaromatization process via conventional and microwave-assisted catalysis

Direct non-oxidative methane dehydroaromatization (DHA) process via conventional and microwave (MW)-assisted thermo-catalytic catalysis is studied. Rate models for methane DHA reactions, including the effect of catalyst deactivation, are developed by using the in-house experimental data. Model results for gas concentration profile and catalyst deactivation are in good agreement with the experimental data. This rate model is then used for the development of dynamic multi-scale, multi-physics commercial-scale reactor models. Total number of fixed bed reactors desired for a cyclic steady state process is estimated. Plant-wide models are then developed for conventional and MW-assisted processes for producing products of desired specifications. Techno-economic analysis of the methane DHA process is undertaken. Economics of these methane DHA processes are compared with the typical multi-step natural gas to aromatics production process via methanol synthesis. Sensitivity of internal rate of return (IRR) and net present value (NPV) to various economic and process parameters such as plant scale, desired rate of return, reactor cost, feedstock and utility cost, catalyst variable cost, and MW reactor cost is studied. Here, electric equivalent efficiency of the conventional methane DHA process is found to be 69.2 % and 67.3 % at 750 °C and 800 °C, respectively, while the MW-assisted methane DHA process has the electric equivalent efficiency of 48.9 % at 800 °C. IRRs of the conventional methane DHA process at 750 °C and 800 °C, and MW-assisted process are 15.2 %, 17.5 %, and 18.8 %, respectively for a methane feed flowrate of 19,782 kg/h, while the IRR of the multi-step natural gas to aromatics production process is estimated to be 0 % for the same plant scale. Impact of change in the methane price, electricity price, and catalyst cost is found to be considerable on the process economics, while the cost of the MW reactor is found to have negligible impact.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Hydrogenation of o -cresol on platinum catalyst: Catalytic experiments and first-principles calculations

We report catalytic experiments were performed for the hydrogenation of o-cresol in n-dodecane over a platinum catalyst. Batch reactions analyzed with an in-situ ATR IR probe suggest that the hydrogenation results in the formation of the final product, 2-methyl-cyclohexanol, with 2-methyl-cyclohexanone as the intermediate product. Ab initio density-functional theory was employed to investigate the atomic-scale mechanism of o-cresol hydrogenation on the Pt(111) surface. The formation of 2-methyl-cyclohexanone was found to involve two steps. The first step is a hydrogen abstraction, that is, the H atom in the hydroxyl group migrates to the Pt surface. The second step is hydrogenation, that is, the pre-existing H atoms on Pt react with the carbon atoms in the aromatic ring. On the other hand, 2-methyl-cyclohexanonol may be produced through two paths, with activation energies slightly greater than that for the formation of 2-methyl-cyclohexanone. One path involves direct hydrogenation of the aromatic ring. Another path involves three steps, with the partial hydrogenation of the ring as the first step, hydrogen abstraction of the single —OH group as the second, and hydrogenation of remaining C atoms and the O atom the last.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Unexpected role of a conserved domain in the first extracellular loop in G protein-coupled receptor trafficking

Highlights: • Most Class A GPCRs contain a conserved WxFG motif. • Substitution of the W with a non-aromatic amino acid disrupts GPCR functioning. • Disrupted GPCR functioning is the due to aberrant plasma membrane localization. G protein-coupled receptors are the largest superfamily of cell surface receptors in the Metazoa and play critical roles in transducing extracellular signals into intracellular responses. This action is mediated through conformational changes in the receptor following ligand binding. A number of conserved motifs have critical roles in GPCR function, and here we focus on a highly conserved motif (WxFG) in extracellular loop one (EL1). A phylogenetic analysis documents the presence of the WxFG motif in ∼90% of Class A GPCRs and the motif is represented in 17 of the 19 Class A GPCR subfamilies. Using site-directed mutagenesis, we mutagenized the conserved tryptophan residue in eight receptors which are members of disparate class A GPCR subfamilies from different taxa. The modification of the Drosophila leucokinin receptor shows that substitution of any non-aromatic amino acid for the tryptophan leads to a loss of receptor function. Additionally, leucine substitutions at this position caused similar signaling defects in the follicle-stimulating hormone receptor (FSHR), Galanin receptor (GALR1), AKH receptor (AKHR), corazonin receptor (CRZR), and muscarinic acetylcholine receptor (mACHR1). Visualization of modified receptors through the incorporation of a fluorescent tag revealed a severe reduction in plasma membrane expression, indicating aberrant trafficking of these modified receptors. Taken together, these results suggest a novel role for the WxFG motif in GPCR trafficking and receptor function.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

From Lignin to Valuable Products–Strategies, Challenges, and Prospects

The exploration of effective approaches for the valorization of lignin to valuable products attracts broad interests of a growing scientific community. By fully unlocking the potential of the world’s most abundant resource of bio-aromatics, it could improve the profitability and carbon efficiency of the entire biorefinery process, thus accelerate the replacement of fossil resources with bioresources in our society. This review summaries the latest cutting-edge innovations of lignin chemical valorization with the focus on the aforementioned three key aspects.

lignin, biofuels↗