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Glycine was applied as the leachant for the hydrothermal leaching of lithium-ion battery (LIB) cathode materials, LiCoO2 and LiNiO2, at 90–180 °C for 5–90 min. LiCoO2 was completely leached at 180 ...

Separation of antioxidant compounds (caffeoylquinic acids (CQAs), phenolics, melanoidin, and caffeine) from green coffee beans with hydrothermal extraction and decomposition kinetics of 3-o-caffeoy...

Winterization is a simple method to remove saturated fatty acid contents in biodiesel fuels for improving their cold flow properties. In this work, biodiesel fuels with different initial long-chain (C16 and above) saturated fatty acid constituents (Si) were prepared from blends of palm, canola, and corn oils. The prepared biodiesels were treated at various winterization temperatures (Tw) to investigate the effect of Tw and Si on the final saturated fatty acid constituents (Sw) of the winterized biodiesel fuel. Optical microscopy showed that ball-like crystals formed with fluid regions at moderate cooling rates (−6 °C/h) could allow solid–liquid separation by filtration. A saturated fatty acid reduction ratio, Rs, defined as (Si – Sw)/Si × 100, was used with the experimental results on large samples (ca. 600 mL) to develop a correlation for winterization temperature as Tw (°C) = 0.659 Si (wt%) – 0.104 Rs (wt%) – 10.197. The correlation can provide estimation of the required winterization temperature for re...

Atmospheric densities and viscosities of ionic liquids, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6C1Im][Tf2N]) and 1-hexyl-3-methylimidazolium chloride ([C6C1Im][Cl]), were measured with a Stabinger viscometer at temperatures from (293 to 373) K. High-pressure densities (p ≤ 200 MPa) for [C6C1Im][Tf2N] and [C6C1Im][Cl] were measured with a bellows type apparatus at temperatures from (312 to 452) K. Samples were analyzed for the water and 1-methylimidazole content before and after the measurements. For [C6C1Im][Tf2N], combined expanded uncertainties were estimated to be (1.0 and 1.8) kg·m–3 for atmospheric and high-pressure density, respectively, and 0.85 % for viscosity. For [C6C1Im][Cl], combined expanded uncertainties were estimated to be (1.1 and 2.5) kg·m–3 for atmospheric and high-pressure density, respectively, and 1.59 % for viscosity. The measured densities and viscosities of [C6C1Im][Tf2N] in this work agreed with some of the available literature values within their experi...

Catalytic cracking of Canadian oil sand bitumen in supercritical water was performed to clarify the effect of CeO2 nanoparticles. The cracking was performed at 723 K to promote a redox reaction between the water, bitumen, and catalyst for the production of hydrogen and oxygen. As the catalyst, CeO2 with two different morphologies was employed because the redox reaction of CeO2 with water and organics is expected and its activity can be controlled by its structure. In this study, two roles of water were considered as well. Water is attractive as a high potential medium with low dielectric constant and density at near the critical point (374 °C, 22.1 MPa) that allows formation of highly crystalline smaller metal oxides particles. However, the chemical effects of water are investigated with heavy oil catalytic cracking. Transmission electron microscopy images indicated that CeO2 nanoparticles with cubic and octahedral shape were synthesized using a plug-flow reactor under hydrothermal conditions. The particl...

Phase equilibrium data for H2 + tetrahydrofuran (THF) and H2 + cyclopentane (CP) binary clathrate hydrate systems were determined from temperature and pressure measurements with a newly designed semimicro (≈ 0.78 cm3) cell. The range of conditions studied for the two systems was at pressures from (2 to 14) MPa and at temperatures from (278 to 285) K. Inclusion characteristics of the hydrogen molecules for both systems were similar according to their Raman spectra. The measured data for the H2 + THF binary clathrate hydrate system were in agreement with some of the data in the literature. New phase equilibrium data and Raman spectroscopy analyses for the H2 + CP binary clathrate hydrate system are reported. The dissociation enthalpies determined from data in the pressure range from (8 to 14) MPa were (212 and 220) kJ·mol−1 for the H2 + THF and H2 + CP binary clathrate hydrate systems, respectively.

Catalytic dehydration of D-fructose to 5-Hydroxymethylfurfural (5-HMF) in acetone/dimethyl sulfoxide solvent mixtures was studied in the presence of a strong acidic cation-exchange resin catalyst (DOWEX 50WX8−100) by microwave heating. The addition of acetone to the dimethyl sulfoxide (DMSO) solvent promoted the formation of 5-HMF from D-fructose. For a D-fructose conversion of 97.9%, the 5-HMF selectivity was 91.7% for a 20-min reaction time in 70:30 (w/w) acetone/DMSO solvent mixtures. Concentrations as high as 10 wt % D-fructose were studied, for which it was found that 5-HMF yields of 82.1% for a reaction time of 10 min could be obtained. The stability of the ion-exchange resin used as the catalyst was confirmed. Compared to pure DMSO solvent, the combination of low-boiling-point acetone with DMSO used as the reaction medium not only gives highly selective 5-HMF formation, but also improves the separation efficiency and reduces environmental risk.

Gasification of lignin and 4-propylphenol, which is a model of low-molecular weight compounds from lignin, over supported metal catalysts in supercritical water was studied at 673 K. Supported ruthenium catalysts were active in supercritical water. The catalytic gasification rate was enhanced by the increase of water density. The gasification of lignin proceeded in supercritical water through two steps: (i) decomposition of lignin to low-molecular weight compounds and (ii) gasification of the low-molecular weight compounds over metal catalysts. The rate of 4-propylphenol gasification was not affected by the water density; this was different from lignin gasification. These results indicated that the first step (decomposition to low-molecular weight compounds) in the lignin gasification was enhanced by increasing the water density.

Lignin and cellulose were gasified at 400 °C with gas yields of 30% and 70%, respectively, in supercritical water with a ruthenium catalyst. In both cases, the main gas product was CH4 and no solid product was formed. Without water or catalyst, lignin and cellulose were gasified slightly and a brown solid product was formed. The decomposition of formaldehyde was also demonstrated in supercritical water. Formaldehyde was rapidly decomposed to gases such as CH4, CO2, and H2 with ruthenium, whereas formaldehyde was converted into methanol and CO2 without catalyst. The catalytic conversion of biomass with ruthenium in supercritical water is an efficient method for biomass gasification at temperatures of ∼400 °C.

Gasification of alkylphenols as lignin model compounds was examined in the presence of supported noble metal catalysts in supercritical water without hydrogen donor at 673 K. The activity of the catalyst was in the order of Ru/γ-alumina > Ru/carbon, Rh/carbon > Pt/γ-alumina, Pd/carbon, and Pd/γ-alumina. The effect of water density with the Ru/γ-alumina catalyst was examined in detail. The main gas products were methane, carbon dioxide, and hydrogen. The yield of gases and the ratio of methane increased with increasing water density. The gasification of the isomers of propylphenols was also examined with the Ru/γ-alumina catalyst. The reactivities of o- and p-propylphenols were relatively higher than those of m-propylphenols.

The decomposition of lignin was examined in supercritical water with and without phenol at 673 K. In the absence of phenol, the yield of tetrahydrofuran (THF)-insoluble (TIS) products decreased and the molecular weight distribution of THF-soluble (TS) products shifted toward lower molecular weights as the water density increased. The increase in water density enhanced the lignin conversion. In the presence of phenol, the yield of TIS products was lower and the molecular weight distribution of TS products shifted toward lower molecular weights than those in the absence of phenol. Some alkylphenols were obtained only in the presence of phenols, because of the reaction of phenol with the decomposition products. These results show that the reaction of phenol with reactive sites occurred in supercritical water and suppressed cross-linking reactions among reactive sites of large fragments. This promoted the decomposition of lignin to lower-molecular-weight compounds.

The decomposition of 2-isopropylphenol at temperatures of 613−713 K and water densities of 0−0.6 g/cm3 yielded phenol, propene, and 2-propylphenol. The decomposition was determined to occur via two reaction pathways: (1) dealkylation of 2-isopropylphenol to produce phenol and propene and (2) rearrangement of the propyl functional group from 2-isopropylphenol to 2-propylphenol. The rate constant for dealkylation increased proportionally with increasing water density. The reaction rate for rearrangement was invariant with the water density. The rate constants for dealkylation and rearrangement could be correlated as a function of temperature and water density with a global reaction model.

We proposed a new model for estimation of the overall rate constant of pyrolysis of n-alkanes at a low conversion level. The model was based on the Kossiakoff and Rice theory, that is, including the following five elementary reactions: initiation, isomerization, β scission, H abstraction, and termination. The carbon number dependence of the rate constant of bimolecular reactions (H abstraction and termination) was taken into account in the model. The model can predict the overall rate constant of n-alkanes (n-C3−n-C32) at a wide range of temperatures (572−973 K) and concentrations (6.86 × 10-3−2.72 M) successfully. Finally, we could explain the carbon number dependence of the overall rate constant of n-alkane pyrolysis from the literature by the theoretical basis.

We propose a new process for the hydrotreatment of heavy oils in supercritical water (SCW). The discussion in this paper is composed of three parts: (1) hydrogenation through water-gas shift reaction in supercritical water, (2) selective formation of carbon monoxide by partial oxidation in supercritical water and through combinations of these two, and (3) hydrogenation of hydrocarbons through their partial oxidation in supercritical water. In the experiments involving hydrogenation of dibenzothiophene, carbazole, and naphthalene, faster hydrogenation rates could be obtained in a CO−SCW atmosphere than in a H2−SCW atmosphere. Even in the case of a H2−CO2−SCW atmosphere, similarly faster reaction rates were obtained, which suggests that an intermediate species of the water-gas shift reaction is the actual reason for the high hydrogenation rates. Partial oxidation experiments were conducted for hexylbenzene and n-hexadecane. The selectivity of CO increased with increasing density of water, while CO2 was the...

Small molecules that inhibit the geranylgeranylation of K-Ras4B and RhoA by protein geranylgeranyltransferase type I (GGTase-I) were identified from chemical genetic screens of heterocycles synthesized through phosphine catalysis of allenes. To further improve the efficacy of the GGTase-I inhibitors (GGTIs), 4288 related compounds bearing core dihydropyrrole/pyrrolidine and tetrahydropyridine/piperidine scaffolds were synthesized on SynPhase lanterns in a split-pool manner through phosphine-catalyzed [3 + 2] and [4 + 2] annulations of resin-bound allenoates. Testing of the 4288 analogues resulted in several GGTIs exhibiting submicromolar IC50 values. Because proteins such as Ras and Rho GTPases are implicated in oncogenesis and metastasis, these GGTIs might ultimately lead to the development of novel antitumor therapeutics.

We conducted a comparative study of catalytic hydrodesulfurization of dibenzothiophene (DBT) with NiMo/Al2O3 at 673 K and 30 MPa, in various atmospheres (H2−SCW, CO−SCW, CO2−H2−SCW, and HCOOH−SCW), using a tube bomb reactor. Higher conversion of DBT was obtained in CO−SCW, CO2−H2−SCW, and HCOOH−SCW than in H2−SCW. These results clearly indicate that a water−gas shift reaction in supercritical water (SCW) produces species which can hydrogenate DBT more effectively than H2 gas. We also conducted another experiment for the partial oxidation of a DBT−hexylbenzene mixture in SCW. Even in the presence of oxygen, effective hydrogenation of DBT took place. This result is probably because CO forms through the partial oxidation of hexylbenzene and converts to the hydrogenating species through a water−gas shift reaction. We think the catalytic desulfurization of heavy oils in SCW will be a promising new technology, since even by introducing oxygen or air instead of hydrogen, an excellent hydrogenating atmosphere can...