The catalytic hydrogenation of fatty acids has witnessed rapid development in recent years. However, the conventional hydrogenation process often requires high-pressure hydrogen. This paper describes a novel protocol to produce fatty alcohols via an in situ hydrogenation of fatty acids in water and methanol using Cu-based catalysts. Cu/ZrO2, Cu/MgO, and Cu/Al2O3 were prepared by the co-precipitation method. All Cu-based catalysts exhibited excellent activity for in situ hydrogenation of fatty acids, and the stability of Cu/ZrO2 was the best. The structures and properties of Cu-based catalysts are demonstrated by transmission electron microscopy, X-ray diffraction, H2 temperature-programmed reduction, N2 adsorption–desorption, CO temperature-programmed desorption, and CO2 temperature-programmed desorption. The stability of Cu/ZrO2 is caused by the good hydrothermal stability and tetragonal phase formation of ZrO2, which strongly binds to active Cu. The better activity over Cu/Al2O3 is caused by the larger surface area, higher Cu dispersion, smaller Cu particle size, and stronger basicity of Cu/Al2O3. Furthermore, the effects of the reaction time, catalyst loading, methanol loading, carbon number, and types of hydrogen donor on in situ hydrogenation of the fatty acids were investigated to demonstrate the reaction behaviors.

•The catalytic fast pyrolysis of cellulose to aromatics was studied over the hierarchical ZSM-5 catalysts prepared by three different alkalis.•Alkali treatment with Na2CO3 was highly controllable, resulting in an increase of the Brønsted acidity and the formation of hierarchical structures.•The highest aromatic and lowest coke yield were obtained over the hierarchical ZSM-5 treated by 0.6 M Na2CO3.•The hierarchical ZSM-5 treated with Na2CO3 increased the selectivity of benzene, toluene, and xylene.Hierarchical ZSM-5 catalysts were prepared by desilication using NaOH, Na2CO3 and TPAOH with different concentrations under the same treatment conditions. Their structures and acidities were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption and desorption (N2-BET) and ammonia temperature-programmed desorption (NH3-TPD). The catalytic fast pyrolysis (CFP) of cellulose to produce aromatics over the hierarchical ZSM-5 catalysts prepared using different alkali treatments was investigated. The alkali treatment by Na2CO3 (0.4 ∼ 0.8 M) was much milder than treatment by NaOH, which allowed the desilication process to be highly controllable, resulting in an increase of both the amount and strength of the strong acid sites, and the formation of hierarchical structures combining micro- and mesoporosity. The organic hydroxide TPAOH did not change the pore structure of ZSM-5, but it greatly increased the relative crystallinity. The CFP of cellulose with HZSM-5 produced 35.5% liquid aromatic hydrocarbons and 32.7% coke. The yield of aromatics increased after Na2CO3 treatment but decreased after NaOH treatment. In addition, the yield of coke showed the opposite trend. The highest aromatic yield (38.2%) and lowest coke yield were obtained in the CFP of cellulose with the desilicated zeolite treated with 0.6 M Na2CO3. The increased acidity in hierarchical ZSM-5 treated with Na2CO3 increased the selectivity of highly valuable aromatics, such as benzene, toluene, and xylene, and decreased the selectivity of large aromatics. TPAOH-treated HZSM-5 showed a slightly increased yield of aromatics due to the repair effect of TPAOH, but this treatment did not form a mesoporous structure.Download high-res image (124KB)Download full-size image

•Catalytic conversion of oleic acid to C17 is measured without H2 and a solvent.•The preadsorbed water on Pt/C modulated the catalytic performance very well.•The heptadecane yield increased to 70% after adsorbing 30 wt% H2O.•The heptadecane yield decreased to 35% when the water was added with dry Pt/C.Preadsorbed water, along with the surrounding environment, significantly modulated the catalytic performance of Pt/C in the conversion of oleic acid to heptadecane. After adsorbing 20 wt% and 30 wt% H2O, the yield of heptadecane increased from 60% over the dried Pt/C to 65% and 70%, respectively. The preadsorbed water on Pt/C increased the acidity and adsorption properties of hydrotropic species, such as carboxyl (COOH), therefore, increasing catalytic performance. This could lead to facile improvement in the efficiency of catalyst performance without complicated or expensive surface modulation.Download high-res image (68KB)Download full-size image

As efficient drug carriers, stimuli-responsive mesoporous silica nanoparticles are at the forefront of research on drug delivery systems. An acid-responsive system based on silyl ether has been applied to deliver a hybrid prodrug. Thiol-ene click chemistry has been successfully utilized for tethering this prodrug to mesoporous silica nanoparticles. Here, by altering the steric bulk of the substituent on the silicon atom, the release rate of a model drug, camptothecin, was controlled. The synthesized drug delivery system was investigated by analytical methods to confirm the functionalization and conjugation of the mesoporous silica nanoparticles. Herein, trimethyl silyl ether and triethyl silyl ether were selected to regulate the release rate. Under normal plasma conditions (pH 7.4), both types of camptothecin-loaded mesoporous silica nanoparticles (i.e., MSN-Me-CPT and MSN-Et-CPT) did not release the model drug. However, under in vitro acidic conditions (pH 4.0), based on a comparison of the release rates, camptothecin was released from MSN-Me-CPT more rapidly than from MSN-Et-CPT. To determine the biocompatibility of the modified mesoporous silica nanoparticles and the in vivo camptothecin uptake behavior, MTT assays with cancer cells and confocal microscopy observations were conducted, with positive results. These functionalized nanoparticles could be useful in clinical treatments requiring controlled drug release.Statement of SignificanceAs the release rate of drug from drug-carrier plays important role in therapy effects, trimethyl silyl ether (TMS) and triethyl silyl ether (TES) were selected as acid-sensitive silanes to control the release rates of model drugs conjugated from MSNs by thiol-ene click chemistry. The kinetic profiles of TMS and TES materials have been studied. At pH 4.0, the release of camptothecin from MSN-Et-CPT occurred after 2 h, whereas MSN-Me-CPT showed immediate drug release. The results showed that silyl ether could be used to control release rates of drugs from MSNs under acid environment, which could be useful in clinical treatments requiring controlled drug release.Download high-res image (188KB)Download full-size image

We herein report an atom-economic approach to produce aviation fuel range hydrocarbons and aromatics from oleic acid without an added hydrogen donor. The effects of catalyst loading, reactant loading, and reaction temperature on the conversion of oleic acid and the yields of hydrocarbons and aromatics were investigated. The conversion of oleic acid was 100%, and the yield of heptadecane (the main product) can reach 71% after 80 min at 350 °C. Moreover, an aromatics yield of 19% was determined, which is the critical composition of the aviation fuels due to their ability to maintain the swelling of fuel system elastomers, indicating that it is a complicated reaction system including in situ hydrogen transfer, aromatization, decarboxylation, and cracking. To probe the mechanism of the conversion of oleic acid without an added hydrogen donor, variations of the reactant and products as time elapsed at different temperatures and the reaction behavior of 1-heptadecene and stearic acid at 350 °C in the catalysis system were investigated. The main mechanism proposed was that oleic acid was decarboxylated to 8-heptadecene, followed by the dehydrogenation of 8-heptadecene to polyenes. Then, polyenes were cyclized to aromatics by an intramolecular Diels–Alder reaction, which provided hydrogen to hydrogenate the unreacted oleic acid to stearic acid. Finally, stearic acid was decarboxylated to heptadecane.

A systematic study on microwave-assisted oxidative degradation of lignin model compounds, such as 2-phenoxy-1-phenylethanol, vanillyl alcohol, and 4-hydroxybenzyl alcohol, was performed by evaluating the catalytic activity of 14 types of metal salts. The acidity of each metal salt solution for the oxidative degradation of 2-phenoxy-1-phenylethanol, vanillyl alcohol, and 4-hydroxybenzyl alcohol under the microwave irradiation and conventional heating conditions was measured and compared. The results showed that CrCl3 and MnCl2 were the most effective for the degradation of the lignin model compounds. The acidity of metal salt is in favor of the catalytic activity for the degradation of 2-phenoxy-1-phenylethanol, vanillyl alcohol, and 4-hydroxybenzyl alcohol, and microwave irradiation is able to accelerate the degradation rate in a large scale. The possible mechanisms for the degradation of 2-phenoxy-1-phenylethanol, vanillyl alcohol, and 4-hydroxybenzyl alcohol are proposed on the basis of the product distributions.

A systematic study of microwave-assisted degradation of lignin model compounds such as benzyl phenyl ether (BPE) and guaiacol, in imidazolium-based ionic liquids, was performed by evaluating the catalytic activity of 29 types of ionic liquids as both solvent and catalyst. After measuring and comparing the acidity of each ionic liquid solution for BPE and guaiacol degradation under the microwave irradiation and conventional heating conditions, it was found that the ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4) was the most effective for decomposing the lignin model compounds. The experimental results indicate that ionic liquid acidity is in favor of the catalytic activity for BPE and guaiacol degradation, microwave irradiation could accelerate the degradation rate by 650% for BPE and 1120% for guaiacol and significantly increase the reaction selectivity. It was also found in experiments that the ionic liquid [BMIM]HSO4 could be used for 5 times without any loss of catalytic activity. The possible mechanisms for BPE and guaiacol degradation are proposed based on the product distributions.

The kinetics and underlying mechanisms of the hydrothermal decomposition of the lignin model compounds anisole, diphenyl ether and phenethyl phenyl ether were studied. Whereas diphenyl ether was stable at hydrothermal conditions, anisole and phenethyl phenyl ether underwent hydrothermal decomposition between 260 and 290 °C. Experiments involving different initial reactant concentrations and different batch holding times revealed that hydrolysis of both anisole and phenethyl phenyl ether followed first-order kinetics. Experiments at different temperatures showed that the first-order rate constants displayed Arrhenius behavior, with activation energies of 149.8 ± 16.4 and 143.2 ± 21.0 kJ·mol–1 for anisole and phenethyl phenyl ether, respectively. A reaction mechanism is proposed for anisole, and reaction pathways for the decomposition of phenethyl phenyl ether are proposed based on the distribution of the products generated by hydrolysis. The reactivity of ether hydrothermal decomposition is discussed by reviewing the published conversion data of other ethers.

The mixed-acid systems of four Lewis acids (FeCl3, CrCl3, ZnCl2, and CuCl2) combining three Brønsted acids (H2SO4, HCl, and H3PO4) were evaluated for the decomposition of glucose to produce levulinic acid (LA). The CrCl3–H3PO4 system had a strong synergic catalytic activity for the decomposition of glucose to LA. The effects of the ratio of CrCl3 and H3PO4 on glucose, fructose, and 5-hydroxymethylfurfural (5-HMF) decompositions were investigated. The mixed-acid system showed the strongest synergic catalytic activity for glucose, fructose, and 5-HMF decompositions when the ratio of CrCl3 in the CrCl3–H3PO4 system was 0.4–0.5. To probe the synergic catalysis mechanism of the CrCl3–H3PO4 system, the synergic catalytic activities of CrCl3–phosphates (KH2PO4, K2HPO4, and K3PO4) systems on glucose decomposition were also evaluated. The possible synergic catalysis mechanisms were proposed. This study provides insights for the synergic catalysis mechanism of hexose conversion to yield LA.

The solubilities of madecassoside in a mixture of methanol + water were determined in the temperature range from (298.15 to 328.15) K by a static analytical method. A “W”-type curve was found for the solubility of madecassoside in the mixture of methanol + water. The induction periods of asiaticoside and madecassoside in a mixture of methanol + water were determined at 298.15 K by a laser scattering method. The results show that the solubilities of madecassoside are similar to those of asiaticoside in the mixture of methanol–water excluding those at high water content and high temperature. However, these two compounds with the only difference of 6-OH exhibit a quite different crystallization property that the induction period of madecassoside is at least 10 times longer than asiaticoside. Moreover, the interfacial tension data of asiaticoside were obtained, which are in the range of (0.55 to 0.86) mJ·m–2.