Highly selective low-temperature hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol catalysed by hectorite-supported ruthenium nanoparticles

Metallic ruthenium nanoparticles intercalated in hectorite (particle size ~ 4 nm) were found to catalyse the hydrogenation of furfuryl acohol to give tetrahydrofurfuryl alcohol in methanolic solution under mild conditions. The best results were obtained at 40 °C under a hydrogen pressure of 20 bar (conversion 100%, selectivity > 99%). After a total turnover number of 1423, the hectorite supported ruthenium nanoparticles are deactivated but can be recycled and regenerated.     

NiFe/γ-Al2O3: A universal catalyst for the hydrodeoxygenation of bio-oil and its model compounds

NiFe bimetallic catalyst shows an excellent activity and selectivity for the hydrodeoxygenation (HDO) of three typical model compounds of bio-oil. The conversion of furfuryl alcohol, benzene alcohol and ethyl oenanthate is 100, 95.48 and 97.89% at 400 °C and the yield to 2-methylfuran, toluene and heptane is 98.85, 93.49 and 96.11% at 0.1 ml/min flow speed and atmospheric pressure. It indicates that the major reaction pathway is the cleavage of C–O rather than C–C. After the catalytic HDO of bio-oil over NiFe/Al₂O₃ catalyst, the heating value changes from 37.8 to 43.9 MJ/kg, the pH changes from 6.65 to 7.50.     

Liquid–liquid equilibria for ternary mixtures of methyl tert-butyl ether,ethyl tert-butyl ether,water and imidazolium-based ionic liquids at 298.15 K

The ternary liquid–liquid equilibria (LLE) were analytically determined at 298.15 K for the following systems: {methyl tert-butyl ether (MTBE) + water + 1-ethyl-3-methylimidazolium-ethylsulfate (EMISE)}, {MTBE + water + 1-butyl-3-methylimidazolium-tetrafluoroborate ([Bmim][BF₄])}, {ethyl tert-butyl ether (ETBE) + water + EMISE}and {ETBE + water + [Bmim][BF₄]}.All the determination were carried out at atmospheric pressure using stirred and thermo-regulated cells. The experimental data were correlated with the well-known NRTL and UNIQUAC activity coefficient models. In addition, distribution coefficients with selectivity of the ionic liquids EMISE and [Bmim][BF₄] for water in the MTBE or ETBE phase were determined.     

Kinetics of high temperature conversion of furfuryl alcohol in water

The kinetics of furfuryl alcohol conversion to 4-hydroxycyclopent-2-enone (4-HCP), polymers and levulinic acid (LA) in water was investigated in batch reactors at temperatures 110–200 °C. These acid catalyzed reactions are at high temperatures catalyzed by hydrogen ions formed by autodissociation of water. At temperatures 180–200 °C and reaction times 5–10 min more than 50 mol% yields of 4-HCP were achieved. A kinetic model which describes experimental data was developed. The values of the apparent activation energies of the main reaction and the side reactions are very similar, what means that the selectivity of 4-HCP formation is independent on the temperature. It indicates, that is attractive to perform furfuryl alcohol transformation to 4-HCP at high temperatures without changing the selectivity.     

Control of the carbon shell thickness in Sn70Ge30@carbon core–shell nanoparticles using alkyl terminators: Its implication for high-capacity lithium battery anode materials

This paper describes the synthesis and electrochemical characterization of Sn₇₀Ge₃₀@carbon core–shell nanoparticles prepared by vacuum annealing of the alkyl-capped Sn₇₀Ge₃₀ nanoparticles obtained from the reaction of SnCl₄ and GeCl₄ with sodium naphthalide in ethylene glycol dimethyl ether (glyme) and RLi (R = butyl, ethyl, methyl). The Sn₇₀Ge₃₀@carbon core–shell nanoparticles have different core sizes and shell thicknesses depending on the alkyl terminator. The annealed nanoparticles that terminate with butyl and ethyl groups have core sizes of ～14 and ～17 nm with carbon shell thicknesses of ～16 and ～8 nm, respectively. On the other hand, annealed nanoparticles that terminate with methyl groups have core sizes of 40 nm with a very thin carbon shell without uniform coverage of the core. Electrochemical characterization shows that nanoparticles prepared using butyl terminators have the highest capacity retention out to 40 cycles (95%) and a first charge capacity of 1040 mAh/g. On the other hand, ethyl- and methyl-capped nanoparticles show 82 and 64% capacity retention after 40 cycles.     

High selective and stable performance of catalytic aromatization of alcohols and ethers over La/Zn/HZSM-5 catalysts

The catalytic conversions of methanol, ethanol, dimethyl ether and diethyl ether to aromatic hydrocarbons (especially benzene, toluene and xylene) were achieved over 0.8%Zn/0.6%La/HZSM-5 catalyst with a BTX selectivity as high as over 50% at reaction conditions of 710 K, WHSV 0.8 h^?1. The selectivity of BTX hydrocarbons in methanol aromatization reaction could remain 35% in 40 h.     

Growth and electron field emission properties of ultrananocrystalline diamond on silicon nanostructures

The electron field emission (EFE) properties of Si nanostructures (SiNS), such as Si nanorods (SiNR) and Si nanowire (SiNW) bundles were investigated. Additionally, ultrananocrystalline diamond (UNCD) growth on SiNS was carried out to improve the EFE properties of SiNS via forming a combined UNCD/SiNS structure. The EFE properties of SiNS were improved after the deposition of UNCD at specific growth conditions. The EFE performance of SiNR (turn-on field, E₀ = 5.3 V/μm and current density, J_e = 0.53 mA/cm² at an applied field of 15 V/μm) was better than SiNW bundles (turn-on field, E₀ = 10.9 V/μm and current density, J_e < 0.01 mA/cm² at an applied field of 15 V/μm). The improved EFE properties with turn-on field, E₀ = 4.7 V/μm, current density, J_e = 1.1 mA/cm² at an applied field of 15 V/μm was achieved for UNCD coated (UNCD grown for 60 min at 1200 W) SiNR. The EFE property of SiNW bundles was improved to a turn-on field, E₀ = 8.0 V/μm, and current density, J_e = 0.12 mA/cm² at an applied field of 15 V/μm (UNCD grown for 30 min at 1200 W).     

Transesterified milkweed (Asclepias) seed oil as a biodiesel fuel

The methyl and ethyl esters of milkweed (Asclepias) seed oil were prepared and compared to soybean esters in laboratory tests to determine biodiesel fuel performance properties. The pour points of the methyl and ethyl milkweed esters measured −6 °C and −10 °C, respectively, which is consistent with the high levels of unsaturation characteristic of milkweed seed oil. The oxidative stabilities measured by OSI at 100 °C were between 0.8 and 4.1 h for all samples tested. The kinematic viscosities determined at 40 °C by ASTM D 445 averaged 4.9 mm²/s for milkweed methyl esters and 4.2 mm²/s for soybean methyl esters. Lubricity values determined by ASTM D 6079 at 60 °C were comparable to the corresponding soybean esters with average ball wear scar values of 118 μm for milkweed methyl esters and 200 μm for milkweed ethyl esters.     

Synthesis of diamond using ultra-nanocrystalline diamonds as seeding layer and their electron field emission properties

A modified nucleation and growth process was adopted so as to improve the electron field emission (EFE) properties of diamonds films. In this process, a thin layer of ultra-nanocrystalline diamonds (UNCD), instead of bias-enhanced-nuclei, were used as nucleation layer for growing diamond films in H₂-plasma. The morphology of the grains changes profoundly due to such a modified CVD process. The geometry of the grains transform from faceted to roundish and the surface of grains changes from clear to spotty. The Raman spectroscopies and SEM micrographs imply that such a modified diamond films consist of UNCD clusters (~ 10–20 nm in size) on top of sp³-bonded diamond grains (~ 100 nm in size). Increasing the total pressure in CVD chamber deteriorated the Raman structure and hence degraded the EFE properties of the films, whereas either increasing the methane content in the H₂-based plasma or prolonged the growth time improved markedly the Raman structure and thereafter enhanced the EFE properties of diamond films. The EFE properties for the modified diamond films can be turned on at E₀ = 11.1 V/μm, achieving EFE current density as large as (J_e) = 0.7 mA/cm² at 25 V/μm applied field.     

Plasma post-treatment process for enhancing electron field emission properties of ultrananocrystalline diamond films

This paper demonstrated the plasma post-treatment (ppt) process for modifying the granular structure of ultrananocrystalline diamond (UNCD) films so as to improve their electron field emission (EFE) properties. The ppt-processed UNCD films exhibited improved EFE properties as turn-on field of E₀ = 7.0 V/μm (J_e = 0.8 mA/cm² at 17.8 V/μm). TEM investigation revealed that the prime factor, which enhanced the EFE properties of the UCND films, is the induction of nano-graphitic clusters due to the ppt-process. However, for achieving such a goal, the granular structure of the primary UNCD layer has to be relatively open. That is, the size of grains should be sufficiently small and the grain boundaries should be of considerable thickness, containing abundant hydro-carbon species. Such a simple and robust process for synthesizing conductive UNCD films is especially useful for practical applications.     

A novel Fe(III) salt-catalyzed monoterpene aerobic oxidation in methyl alcohol

The Fe(III)-catalyzed aerobic oxidation of monoterpenes in CH₃OH has been developed, in which simple Fe(III) salts are used as catalysts in the absence of stabilizing ligands. Remarkably, Fe(NO₃)₃ catalyst efficiently promotes the oxidation of monoterpenes under air or dioxygen. The highest TON and TOF reached 476 and 162 h^− 1, respectively. In general, reactions with 1.0–9.0 mol% of catalyst reached high conversions (ca. 90–99%) and high oxidation products selectivity (ca. 80%). Notably, α-pinene and β-pinene were selectively oxidized into only allylic product, myrtenol methyl ether. The significant breakthroughs of this simple oxidative process are the use of inexpensive Fe(III) salts as catalysts and environmentally-friendly oxidants (air or dioxygen).     

An efficient method for the enrichment of the arachidonic acid methyl ester from Mortierella alpina-derived crude oils

An improved method was developed for enriching arachidonic acid (AA) methyl ester from microbial oil by two-step low-temperature wet fractionation. The effects of solvent, operating temperature, and solvent-to-fatty acid methyl esters (FAMEs) ratio on the enrichment of AA were investigated. The best results were achieved when n-hexane was used as solvent. With operating temperatures in the range ?30 °C to ?80 °C and a FAMEs-to-solvent ratio of 1:5 (v/v), the proportion of AA methyl ester isolated could be increased to 83.76 ± 2.78% with a yield of 52.89%. The total recovery of AA methyl ester would be further increased to 90.84% by recrystallization of the solid phases. The 20C, 22C saturated fatty acids were enriched by n-hexane or petroleum ether at ?30 °C, with concentrations increased 7.5-fold or 7.2-fold compared with their original levels, respectively. In addition, a method that combined alkali and acid catalysis of the transmethylation was the most conducive to the preparation of polyunsaturated fatty acid methyl esters.     

Preparation and application of Ba/ZSM-5 zeolite for reaction of methyl vinyl ether and methanol

The ZSM-5 zeolite is widely used to catalyze the reactions of methanol to olefins. Herein, we have prepared the H-ZSM-5 doped with barium (Ba/ZSM-5) using incipient wetness impregnation method. The Ba modified catalysts were used to catalyze a new reaction of methanol with methyl vinyl ether to improve the selectivity of ethylene and propylene (C₂⁼ + C₃⁼). The reaction catalyzed by Ba doped H-ZSM-5 shows higher propylene selectivity over H-ZSM-5. The reaction mechanism is discussed.     

A novel organocatalyst for direct asymmetric Michael additions of cyclohexanone to nitroolefins

A novel catalyst combining pyrrolidinyl and cyclohexanediamine was designed and synthesized. Only 5 mol% of catalyst loading was required for enantioselective Michael additions of cyclohexanone and nitroolefins affording desired γ-nitroketones with > 99% yield, up to 91% ee and up to > 99/1 dr under mild conditions. The enantioselectivity of the product could be further improved to > 99% ee after a single recrystallization in petroleum ether/ethyl acetate.     

One-step synthesis of mesoporous H4SiW12O40-SiO2 catalysts for the production of methyl and ethyl levulinate biodiesel

A novel one-step method for the synthesis of mesoporous H₄SiW₁₂O₄₀-SiO₂ catalysts with tunable composition was successfully developed using non-ionic polyethylene glycol dodecyl ether (Brij 30) as the structure-directing template. Different loadings of H₄SiW₁₂O₄₀ (up to 30 wt.%) were effectively confined within the mesoporous channels of SiO₂, which would facilitate easy recycling and allow for the efficient mass transport of reactants and products. The resultant mesoporous H₄SiW₁₂O₄₀-SiO₂ showed high catalytic activity for the production of methyl and ethyl levulinate biodiesel. The 20 wt.% H₄SiW₁₂O₄₀-SiO₂ catalyst exhibited the best performance in the synthesis of both methyl levulinate (73% yield achieved at 79% conversion of levulinic acid) and ethyl levulinate (67% yield obtained at 75% conversion of levulinic acid).     

The transesterification of dimethyl carbonate and phenol catalyzed by 12-molybdophosphoric salts

Various 12-molybdophosphoric salts were used in the transesterification of dimethyl carbonate (DMC) and phenol to diphenyl carbonate (DPC) and methyl phenyl carbonate (MPC) as novel solid catalysts. The zinc salt was found to exhibit the highest activity for the transesterification. Several parameters affecting the transesterification were investigated. When the reaction was performed between 150 °C and 180 °C, with a molar ratio of phenol to DMC of 1, a reaction time 12 h, a catalyst amount 0.004 (molar ratio to phenol), the conversion of phenol reached 31%, and the selectivity of MPC and DPC was 29% and 66.1%, respectively. The TON reached 74.8 mol (MPC + DPC)/mol Zn-salt.     

High pressure phase equilibria of ethyl esters in supercritical ethane and propane

The high pressure phase equilibria of ethyl esters (ethyl decanoate/caprate, ethyl dodecanoate/laurate, ethyl tetradecanoate/myristate and ethyl hexadecanoate/palmitate) in supercritical ethane and propane have been measured in the temperature ranges 311–358 K (T_R = 1.02–1.17) and 376–409 K (T_R = 1.02–1.11), respectively. The measurements were conducted in a high pressure view cell for ethyl ester mass fractions between 0.015 and 0.65. The results show a generally linear relationship between the phase transition temperature and pressure. No temperature inversions or three phase regions were observed. An increase in hydrocarbon backbone length leads to an increase in phase transition pressure. For ethane as supercritical solvent, this increase is linear. For propane as supercritical solvent, the nature of the increase was not quantified as the magnitude of the increase would be significantly influenced by the experimental measurement error as the observed increase is not very large. Comparison of the phase behaviour of ethyl esters with methyl esters shows very little difference, yet the phase transition pressure of ethyl esters in supercritical ethane and propane is significantly lower than those of the corresponding acids. The phase transition pressure of ethyl esters in ethane and propane is also lower than those in carbon dioxide.     

Highly active and selective ethylene oligomerization catalysts: Asymmetric 2,6-bis(imino)pyridyl iron (II) complexes with alkyl and halogen substitutients

A series of asymmetric 2,6-bis(arylimino)pyridines with alkyl and halogen substitutients on different iminoaryl rings and corresponding iron (II) complexes ([2-(Ar₁N = CCH₃)-6-(Ar₂N = CCH₃)C₅H₃N]FeCl₂, 3a–3j) are synthesized and characterized. These Fe(II) complexes are highly active for ethylene oligomerization with high selectivity for linear α-olefins. The oligomer distributions can be tuned by the synergism of alkyl-steric effect and halogen electronic effect, and the production of C₆–C₁₆ can reach more than 80% with the highest selectivity being 87.5% for 3 g (Ar₁ = 2-ethylphenyl, Ar₂ = 2-fluorophenyl), which is 15–30% higher than that catalyzed by their methyl or fluoro-substituted symmetric counterparts.     

Formation of MUA (mercaptoundeconic acid)-capped CDSe nanoparticle films by electrophoretic deposition

Electrophoretic deposition (EPD) has gained increasing interest for the deposition of materials such as TiO₂, carbon nanotubes and trioctylphosphine oxide (TOPO)-capped CdSe nanoparticles. In this study, a mercaptoundecanoic acid (MUA) CdSe nanoparticle film was formed by electrophoretic deposition. A colloidal suspension of TOPO-capped CdSe nanoparticles was prepared by the hot injection method, followed by ligand exchange to produce MUA-capped CdSe nanoparticles. As-prepared MUA-capped CdSe nanoparticles were washed using ethyl acetate and ethyl ether. Then, the washed nanoparticles were resuspended in ethanol and immediately used for EPD. A CdSe nanoparticle film measuring 2.75 µm in thickness was deposited at an applied voltage of 5 V and deposition time of 5 min.     

Selective conversion of dihydroxyacetone–ethanol mixture into ethyl lactate over amphoteric ZrO2–TiO2 catalyst

The conversion of dihydroxyacetone in ethanol solution into ethyl lactate over several acidic and amphoteric oxides at 100–160 °C was studied. The formation of ethyl lactate with 80–90% selectivity was observed on amphoteric ZrO₂–TiO₂ oxide whereas hemiacetal and acetal of pyruval were the main products obtained over the acidic ZrO₂–SiO₂ catalyst and Amberlyst 15. Amphoteric ZrO₂–3TiO₂ oxide provides 89% yield of ethyl lactate at 140 °C and 1.0 MPa under the feed rate of 4 mmol C₃H₆O₃/g_cat/h.