Catalytic Ethanolysis of Kraft Lignin into High‐Value Small‐Molecular Chemicals over a Nanostructured α‐Molybdenum Carbide Catalyst

We report the complete ethanolysis of Kraft lignin over an α‐MoC_1?x/AC catalyst in pure ethanol at 280 °C to give high‐value chemicals of low molecular weight with a maximum overall yield of the 25 most abundant liquid products (LP25) of 1.64 g per gram of lignin. The LP25 products consisted of C₆–C₁₀ esters, alcohols, arenes, phenols, and benzyl alcohols with an overall heating value of 36.5 MJ kg^?1. C₆ alcohols and C₈ esters predominated and accounted for 82 wt % of the LP25 products. No oligomers or char were formed in the process. With our catalyst, ethanol is the only effective solvent for the reaction. Supercritical ethanol on its own degrades Kraft lignin into a mixture of small molecules and molecular fragments of intermediate size with molecular weights in the range 700–1400, differing in steps of 58 units, which is the weight of the branched‐chain linkage C₃H₆O in lignin. Hydrogen was found to have a negative effect on the formation of the low‐molecular‐weight products.     

Fenton’s reagent-mediated degradation of residual Kraft black liquor

In this work, the effect of Fento’s reagent on the degradation of residual Kraft black liquor was investigated. The effect of Fenton’s reagent on the black liquor degradation was dependent on the concentration of H₂O₂. At low concentrations (5 and 15 mM) of H₂O₂, Fenton’s reagent caused the degradation of phenolic groups (6.8 and 44.8%, respectively), the reduction of reaction medium pH (18.2%), and the polymerization of black liquor lignin. At a high concentration (60 mM) of H₂O₂, Fenton’s reagent induced an extensive degradation of lignin (95–100%) and discoloration of the black liquor. In the presence of traces of iron, the addition of H₂O₂ alone induced mainly lignin fragmentation. In conclusion, Fenton’s reagent and H₂O₂ alone can degrade residual Kraft black liquor under acidic conditions at room temperature.     

All Organic Sodium‐Ion Batteries with Na4C8H2O6

Developing organic compounds with multifunctional groups to be used as electrode materials for rechargeable sodium‐ion batteries is very important. The organic tetrasodium salt of 2,5‐dihydroxyterephthalic acid (Na₄DHTPA; Na₄C₈H₂O₆), which was prepared through a green one‐pot method, was investigated at potential windows of 1.6–2.8 V as the positive electrode or 0.1–1.8 V as the negative electrode (vs. Na⁺/Na), each delivering compatible and stable capacities of ca. 180 mAh g^?1 with excellent cycling. A combination of electrochemical, spectroscopic and computational studies revealed that reversible uptake/removal of two Na⁺ ions is associated with the enolate groups at 1.6–2.8 V (Na₂C₈H₂O₆/Na₄C₈H₂O₆) and the carboxylate groups at 0.1–1.8 V (Na₄C₈H₂O₆/Na₆C₈H₂O₆). The use of Na₄C₈H₂O₆ as the initial active materials for both electrodes provided the first example of all‐organic rocking‐chair SIBs with an average operation voltage of 1.8 V and a practical energy density of about 65 Wh kg^?1.     

Degradation and detoxification mechanisms of organophosphorus flame retardant tris(1,3-dichloro-2-propyl) phosphate (TDCPP) during electrochemical oxidation process

Electrochemical oxidation of aqueous tris(1,3-dichloro-2-propyl) phosphate (TDCPP) by using Ti/SnO₂-Sb/La-PbO₂ as anode was investigated for the first time, and the degradation mechanisms and toxicity changes of the degradation intermediates were further determined. Results suggested that electrochemical degradation of TDCPP followed pseudo-first-order kinetics, and the reaction rate constant (k) was 0.0332 min⁻¹ at the applied current density of 10 mA/cm² and Na₂SO₄ concentration of 10 mmol/L. There was better TDCPP degradation performance at higher current density. Free hydroxy radical (^•OH) was proved to play dominant role in TDCPP oxidation via quenching experiment, with a relative contribution rate of 60.1%. A total of five intermediates (M1, C₆H₁₁Cl₄O₄P; M2, C₃H₇Cl₂O₄P; M3, C₉H₁₆Cl₅O₅P; M4, C₉H₁₄Cl₅O₆P; M5, C₆H₁₀Cl₃O₆P) were identified, and the intermediates were further degraded prolonging with the reaction time. Flow cytometer results suggested that the toxicity of TDCPP and degradation intermediates significantly reduced, and the detoxification efficiency was achieved at 78.1% at 180 min. ECOSAR predictive model was used to assess the relative toxicity of TDCPP and the degradation intermediates. The EC₅₀ to green algae was 3.59 mg/L for TDCPP, and the values raised to 84, 574, 54.6, 391, and 8920 mg/L for M1, M2, M3, M4, and M5, respectively, indicating that the degradation intermediates are less toxic or not toxic. Electrochemical advanced oxidation process is a valid technology to degrade TDCPP and pose a good detoxification effect.     

Tailored Organic Electrode Material Compatible with Sulfide Electrolyte for Stable All‐Solid‐State Sodium Batteries

All‐solid‐state sodium batteries (ASSSBs) with nonflammable electrolytes and ubiquitous sodium resource are a promising solution to the safety and cost concerns for lithium‐ion batteries. However, the intrinsic mismatch between low anodic decomposition potential of superionic sulfide electrolytes and high operating potentials of sodium‐ion cathodes leads to a volatile cathode–electrolyte interface and undesirable cell performance. Here we report a high‐capacity organic cathode, Na₄C₆O₆, that is chemically and electrochemically compatible with sulfide electrolytes. A bulk‐type ASSSB shows high specific capacity (184 mAh g^?1) and one of the highest specific energies (395 Wh kg^?1) among intercalation compound‐based ASSSBs. The capacity retentions of 76 % after 100 cycles at 0.1 C and 70 % after 400 cycles at 0.2 C represent the record stability for ASSSBs. Additionally, Na₄C₆O₆ functions as a capable anode material, enabling a symmetric all‐organic ASSSB with Na₄C₆O₆ as both cathode and anode materials.     

Sodium phenoxy­acetate hemihydrate

The structure of the hemihydrate of sodium phenoxy­acetate, Na⁺·C₈H₇O₃⁻·0.5H₂O, has been redetermined at low temperature (160 K). The structure consists of ribbons containing octahedral NaO₆ units, and half of the Na₂O₂ squares within the ribbon are bridged by water mol­ecules which lie across twofold rotation axes in C2/c. The phenyl substituents lie on the outside of the ribbon.     

Sodium di­hydrogen tris­(cyclo­propane­carboxyl­ate)

The title acid salt, Na⁺·C₄H₅O₂^?·2C₄H₆O₂, contains finite anions in which two cyclo­propanoic acid mol­ecules are hydrogen bonded to a cyclo­propanoate residue. Each such anion interacts with four different Na⁺ cations.     

Sodium citrate dihydrate doped with Mn3+ ions

Sodium citrate dihydrate doped with Mn³⁺ ions, namely trisodium(I) managnese(III) citrate(3−) dihydrate, [Na₃Mn_0.011(C₆H₅O₇)(H₂O)₂]_n, was obtained during attempts to prepare some complex Mn^III citrates from a concentrated strong alkaline solution containing Na⁺, Mn³⁺ and citrate ions. The compound is isostructural with the recently described Na₃(C₆H₅O₇)·2H₂O [Fischer & Palladino (2003). Acta Cryst. E 59 , m1080–m1082]. The essential difference between these two structures is the presence of a very small proportion (0.205 wt%) of Mn³⁺ ions, which are positioned at the special 4e Wyckoff position in C2/c, where they are in a highly distorted octahedral environment of O atoms from two citrate anions.     

Preparation of sodium dimolybdate by the pyrolysis of sodium oxomolybdenum (VI) oxalate

Thermal studies on various oxalato complexes have been of immense interest as they yield finely divided, highly reactive oxides which are usually obtained at a much lower temperature than that required in the conventional method of preparation, i.e., heating a mixture of two or more constituents [1]. A survey of the literature reveals that the compounds having the general formula A₂[Mo₂O₅(C₂O₄)₂(H₂O)₂], where A = K⁺, NH⁺₄[2] and A = Cs⁺ [3], have been prepared and their thermal decomposition is studied, but no such information is available regarding the preparation and characterisation of Na₂[Mo₂O₅(C₂O₄)₂(H₂O)₂] (SMO), which forms the subject of study of this paper. Sodium dimolybdate (Na₂Mo₂O₇), the decomposition product of SMO, is obtained at 280°C, a temperature much lower than that required in the conventional method of preparation of heating a mixture of Na₂MoO₄ and MoO₃ [4].     

Bis-oxalatobisfluoro-aluminates and -gallates

The preparations of some bisoxalatobisfluoroaluminates having the general formula M₃[Al(C₂O₄)₂F₂.3H₂O], where M=K⁺, Na⁺ and [Co(NH₃)₆]³⁺, and a bisoxalatobisfluorogallate, [Co(NH₃)₆] [Ga(C₂O₄)₂F₂].3H₂O, are described. The compounds are characterised by chemical analyses, TGA, IR spectroscopy and X-ray powder photography. IR spectra support the presence of chelating oxalate ligands in these compounds. On isothermal heating at 100–130°C the compounds yield their respective anhydrous products.     

Thermodynamics of sodium 5-methylisophthalic acid monohydrate and sodium isophthalic acid hemihydrate

Two crystal samples, sodium 5-methylisophthalic acid monohydrate (C₉H₆O₄Na₂·H₂O, s) and sodium isophthalic acid hemihydrate (C₈H₄O₄Na₂·1/2H₂O, s), were prepared from water solution. Low-temperature heat capacities of the solid samples for sodium 5-methylisophthalic acid monohydrate (C₉H₆O₄Na₂·H₂O, s) and sodium isophthalic acid hemihydrate (C₈H₄O₄Na₂·1/2H₂O, s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 379 K. The experimental values of the molar heat capacities in the measured temperature region were fitted to a polynomial equation on molar heat capacities (C _p,m) with the reduced temperatures (X), [X = f(T)], by a least-squares method. Thermodynamic functions of the compounds (C₉H₆O₄Na₂·H₂O, s) and (C₈H₄O₄Na₂·1/2H₂O, s) were calculated based on the fitted polynomial equation. The constant-volume energies of combustion of the compounds at T = 298.15 K were measured by a precise rotating-bomb combustion calorimeter to be Δ_c U(C₉H₆O₄Na₂·H₂O, s) = −15428.49 ± 4.86 J g⁻¹ and Δ_c U(C₈H₄O₄Na₂·1/2H₂O, s) = −13484.25 ± 5.56 J g⁻¹. The standard molar enthalpies of formation of the compounds were calculated to be Δ _f H _m ^θ (C₉H₆O₄Na₂·H₂O, s) = −1458.740 ± 1.668 kJ mol⁻¹ and Δ _f H _m ^θ (C₈H₄O₄Na₂·1/2H₂O, s) = −2078.392 ± 1.605 kJ mol⁻¹ in accordance with Hess’ law. The standard molar enthalpies of solution of the compounds, Δ _sol H _m ^θ (C₉H₆O₄Na₂·H₂O, s) and Δ _sol H _m ^θ (C₈H₄O₄Na₂·1/2H₂O, s), have been determined as being −11.917 ± 0.055 and −29.078 ± 0.069 kJ mol⁻¹ by an RD496-2000 type microcalorimeter. In addition, the standard molar enthalpies of hydrated anion of the compounds were determined as being Δ _f H _m ^θ (C₉H₆O₄ ²⁻, aq) = −704.227 ± 1.674 kJ mol⁻¹ and Δ _f H _m ^θ (C₈H₄O₄Na₂ ²⁻, aq) = −1483.955 ± 1.612 kJ mol⁻¹, from the standard molar enthalpies of solution and other auxiliary thermodynamic data through a thermochemical cycle.     

Gas‐phase fragmentation of metal adducts of alkali‐metal oxalate salts

Upon collisional activation, gaseous metal adducts of lithium, sodium and potassium oxalate salts undergo an expulsion of CO₂, followed by an ejection of CO to generate a product ion that retains all three metals atoms of the precursor. Spectra recorded even at very low collision energies (2 eV) showed peaks for a 44‐Da neutral fragment loss. Density functional theory calculations predicted that the ejection of CO₂ requires less energy than an expulsion of a Na⁺ and that the [Na₃CO₂]⁺ product ion formed in this way bears a planar geometry. Furthermore, spectra of [Na₃C₂O₄]⁺ and [³⁹K₃C₂O₄]⁺ recorded at higher collision energies showed additional peaks at m/z 90 and m/z 122 for the radical cations [Na₂CO₂]^+? and [K₂CO₂]^+?, respectively, which represented a loss of an M^? from the precursor ions. Moreover, [Na₃CO₂]⁺, [³⁹K₃CO₂]⁺ and [Li₃CO₂]⁺ ions also undergo a CO loss to form [M₃O]⁺. Furthermore, product‐ion spectra for [Na₃C₂O₄]⁺ and [³⁹K₃C₂O₄]⁺ recorded at low collision energies showed an unexpected peak at m/z 63 for [Na₂OH]⁺ and m/z 95 for [³⁹K₂OH]⁺, respectively. An additional peak observed at m/z 65 for [Na₂¹⁸OH] ⁺ in the spectrum recorded for [Na₃C₂O₄]⁺, after the addition of some H₂¹⁸O to the collision gas, confirmed that the [Na₂OH] ⁺ ion is formed by an ion–molecule reaction with residual water in the collision cell. Copyright © 2014 John Wiley & Sons, Ltd.     

Activation of Kraft Lignin by an Enzymatic Treatment with a Versatile Peroxidase from Bjerkandera sp. R1

Enzymatic lignin activation may be an environmentally friendly alternative to the use of chemicals in the production of wood fibers composites. Most studies on enzymatic activation of lignin for improving the adhesion of lignocellulosic products have been carried out using laccases. In this work, the use of a versatile peroxidase (VP) from the white-rot fungus Bjerkandera sp. (anamorph R1) for activating Kraft lignin was studied. The effect of enzyme dosage, incubation time, and H₂O₂ addition profile on lignin activation was evaluated by quantifying the phenoxy radicals formed using electron paramagnetic resonance (EPR) spectroscopy. Two alternative enzymatic systems based on the use of VP (a two-stage and an enzymatic cascade system) were also assayed. At optimal conditions (dose of 15 U?g^?1 and continuous addition of H₂O₂ (5.24 μmol?h^?1) during 1 h) the content of phenoxy radicals was doubled as compared with an untreated control. Moreover, using the two-stage VP system, a lignin activation similar to that found at optimal conditions could be reached in a shorter time.     

Polyol-Metall-Komplexe. XIII [1]. Na2[Be(C4H6O3)2] · 5H2O und Na2[Pb(C4H6O3)2] · 3H2O – zwei homoleptische Bis-polyolato-metallate mit Beryllium und mit Blei

Polyol Metal Complexes. XIII. Na₂[Be(C₄H₆O₃)₂] · 5H₂O and Na₂[Pb(C₄H₆O₃)₂] · 3H₂O – Two Homoleptic Bis Polyolato Metallates with Beryllium and with Lead Na₂[Be(C₄H₆O₃)₂] · 5H₂O ( 1 ) and Na₂[Pb(C₄H₆O₃)₂] · 3H₂O ( 2 ) crystallize from concentrated, alkaline aqueous solutions. The polyol anhydroerythritol is deprotonated twice in the mononuclear, homoleptic complex anions. The preference of beryllium for the binding of cis-furanoid diols is shown. In 2 , a stereochemically active lone pair at the central atom is the reason for the construction of low dimensional aggregates from three plumbate and three sodium ions.     

Protonation and methylation of η4-2,3,5,6-tetramethyl-1,4-benzoquinone(η5-pentamethylcyclopentadienyl)cobalt

The preparation of the η⁴-4-2,3,5,6-tetramethyl-1,4-benzoquinonecomplex [CO(C₅Me₅)(C₁₀H₁₂O₂)] (I) is reported. Complex I undergoesreversible protonation to yield the 2-6-η-4-hydroxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C₅Me₅)(C₁₀H₁₃O₂)BF₄ (II) and diprotonation to yield the η⁶-6-1,4-dihydroxy-2,3,5,6-tetramethylbenzene complex [Co(C₅Me₅)(C₁₀H₁₄O₂)] (BF₄)₂ (III). Methylation of complex I with MeI/AgPF₆ gives the 26-η-4-methoxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C₅Me₅)(C₁₁H₁₅O₂])PF₆ (IV). In trifluoroacetic acid solution complex IV is protonated to form the η⁶-1-hydroxy-4-methoxy-2,3,5,6-tetramethylbenzene cation [Co(C₅Me₅)-(C₁₁H₁₆O₂)]²⁺     

Synthesis of Na2WO4-MnxOy supported on SiO2 or La2O3 as fiber catalysts by electrospinning for oxidative coupling of methane

The oxidative coupling of methane (OCM) is an attractive route to convert natural gas directly into value-added chemical products (C₂₊). This work comparatively investigated SiO₂- or La₂O₃-supported Na₂WO₄-Mn_xO_y (denoted as NWM) catalysts in powder and fiber forms. The powder catalysts were prepared using a co-impregnation method and the fiber catalysts were prepared successfully using an electrospinning technique. The NWM/La₂O₃ fiber catalysts were activated at low temperature (500 °C) and had a 4.7% C₂₊ yield, with the maximum C₂₊ yield of 9.6% at 650 °C, while the NWM/SiO₂ fiber catalyst was activated at 650 °C and had a maximum C₂₊ yield of 20.4% at 700 °C. The XPS results in the O 1s region indicated that NWM/La₂O₃ had a lower binding energy than NWM/SiO₂, suggesting that the lattice oxygen species is easily released from the catalyst surface and creates vacancy sites that enhance performance. The stability test of the catalysts indicated that the La₂O₃-containing catalysts had excellent activity and high thermal stability, while the SiO₂-containing catalysts had a higher C₂₊ yield when the prepared catalysts were compared at 700 °C. Considering the same component catalysts, the fiber catalysts achieved higher performance because their heat and mass transfer properties were enhanced.     

Depolymerization and hydrodeoxygenation of lignin to aromatic hydrocarbons with a Ru catalyst on a variety of Nb-based supports

Efficient conversion of lignin to aromatic hydrocarbons via depolymerization and subsequent hydrodeoxygenation is important. Previously, we found that NbO_x species played a key role in the activation and cleavage of C–O bonds in lignin and its model compounds. In this study, commercial niobic acid (HY-340), niobium phosphate (NbPO-CBMM) and lab-made layered niobium oxide (Nb₂O₅-Layer) were chosen as supports to study the effect of Brönsted and Lewis acids on the activation of C–O bonds in lignin conversion. A variety of Ru-loaded, Nb-based catalysts with different Ru particle sizes were prepared and applied to the conversion of p-cresol. The results show that all the Ru/Nb-based catalysts produce high mole yields of C₇–C₉ hydrocarbons (82.3–99.1%). What's more, Ru/Nb₂O₅-Layer affords the best mole yield of C₇–C₉ hydrocarbons and selectivity for C₇–C₉ aromatic hydrocarbons, of up to 99.1% and 88.0%, respectively. Moreover, it was found that Lewis acid sites play important roles in the depolymerization of enzymatic lignin into phenolic monomers and the cleavage of the C–O bond of phenols. Additionally, the electronic state and particle size of Ru are significant factors which influence the selectivity for aromatic hydrocarbons. A partial positive charge on the metallic Ru surface and a smaller Ru particle size are beneficial in improving the selectivity for aromatic hydrocarbons.     

Disodium tetrakis(hexanoato‐O)zinc(II)

The structure of the title compound, Na₂[Zn(C₆H₁₁O₂)₄], consists of two‐dimensional polymeric sheets. The Zn²⁺ ions are approximately tetrahedrally coordinated by O atoms from different hexanoate anions. Both Na⁺ ions are six‐coordinated by carboxyl­ate O atoms. One of the hexanoate O atoms is attached to one Zn²⁺ ion and one Na⁺ ion, and the remaining O atom is attached to two Na⁺ ions.     

Heterogeneous methane oxidative coupling using perovskites

Catalytic oxidative coupling of methane over perovskite CaTiO₃ prepared by modified ceramic method has been studied. The C₂ yield was 13% at 830 °C and promotion with Na₄P₂O₇ did not improve considerably the catalyst peformance. Regarding reactor test and mechanism studies it is believed that charge deficient, oxygen O^– generated by transforming oxygen adsorbed on surface defects and dissolved into bulk vacancies is responsible for activating methane (active site). Adsorbed oxygen generates the oxidizing sites for actived methane. Strict conditions are required for generation and regeneration of the activating sites in lattice.     

One-step fabrication of mesoporous sulfur-doped carbon nitride for highly selective photocatalytic transformation of native lignin to monophenolic compounds

Photocatalytic selective transform native lignin into valuable chemicals is an attractive but challenging task. Herein, we report a mesoporous sulfur-doped carbon nitride (MSCN-0.5) which is prepared by a facile one-step thermal condensation strategy. It is highly active and selective for the cleavage Cα?C_β bond in β?O?4 lignin model compound under visible light radiation at room temperature, achieving 99% substrate conversion and 98% C_α?C_β bond cleavage selectivity. Mechanistic studies revealed that the C_β?H bond of lignin model compounds activated by holes and generate key C_β radical intermediates, further induced the C_α?C_β bond cleavage by superoxide anion radicals (^?O₂^?) to produce aromatic oxygenates. Waste Camellia oleifera shell (WCOS) was taken as a representative to further understand the reaction mechanisms on native lignin. 33.2 mg of monophenolic compounds (Vanillin accounted for 22% and Syringaldehyde for 34%) can be obtained by each gram of WCOS lignin, which is 2.5 times as that of the pristine carbon nitride. The present work offers useful guidance for designing metal-free heterogeneous photocatalysts for C_α?C_β bond cleavage to harvest monophenolic compounds.