•BTP was first used in synthesis of palladium-rich shell bimetallic nanoparticles.•BTP pulls Pd to the shell of the nanoparticles by coordinating with Pd2 +.•PdNi-BTP/SiO2 was active for hydrogenation of nitrobenzene in ambient conditions.•PdNi-BTP/SiO2 was stable and active after removal of BTP.A series of PdNi/SiO2 bimetallic nanoparticles were synthesized using polyvinylpyrrolidone (PVP) and 2,6-bis(5,6-dimethyl-1,2,4-triazine-3-yl) pyridine (BTP) as ligands through sol-gel method. BTP was proved to be an effective ligand that can delay the reduction of palladium (II), which helps the formation of palladium-rich shell bimetallic nanoparticles. Pd3Ni7-BTP/SiO2 exhibited the best catalytic performance (TOF = 180 h− 1) among all the catalysts for hydrogenation of nitrobenzene under ambient conditions and was successfully reused for at least five times without loss in activity. The excellent catalytic performance could be ascribed to the small nanoparticle size (2.14 nm) and the palladium-rich shell structure it bears.Download high-res image (82KB)Download full-size image

•Nitrogen-doped mesoporous carbon (NMC) supported Pt catalyst was successfully prepared.•Pt supported on NMC is more effective than on AC and MC for fatty acids decarboxylation to alkanes.•Nitrogen species can improve the anchoring and the dispersion of Pt nanoparticles and provide basic sites to adsorb fatty acids.Mesoporous carbon (MC) and nitrogen-doped mesoporous carbon (NMC) were prepared through a dual-template approach with tetraethyl orthosilicate and Pluronic F127 as a dual-template, and phenol-formaldehyde and melamine-phenol-formaldehyde resins as carbon and carbon + nitrogen sources, respectively. Using them as the supports, the Pt/MC and Pt/NMC catalysts were prepared by incipient wetness impregnation method and used for the decarboxylation of saturated and unsaturated fatty acids to alkanes. Activated carbon supported Pt catalyst (Pt/AC) was also prepared for comparison. Among the three catalysts, Pt/NMC exhibited the highest catalytic performance, achieving yields of the corresponding alkanes of more than 97.0% from lauric, myristic, palmitic and stearic saturated acids and 44.0%–66.1% from oleic and linoleic unsaturated fatty acids. The turnover frequencies of Pt/NMC were estimated as 335–522 h−1 in the decarboxylation of saturated acids, which were almost 2-fold higher than Pt/MC and 3-fold higher than Pt/AC. The excellent performance of the Pt/NMC catalyst might be attributed to the introduction of N species to the MC support, which not only improved the anchoring and the dispersion of Pt nanoparticles on the catalyst surface, but also provided alkaline sites to adsorb carboxyl group in fatty acids.Download high-res image (183KB)Download full-size image

RANEY® Ni proved to be an effective heterogeneous catalyst for switchable reductive amination of furfuryl alcohol to tetrahydrofurfurylamine and furfurylamine with NH3 by simply adding or not adding 1.0 MPa H2 into the reaction bulk. After further optimization of the reaction conditions, we finally obtained 94.0% yield of tetrahydrofurfurylamine and 78.8% yield of furfurylamine with high selectivity. By extensively studying the catalytic pathways and mechanism of catalyst deactivation with XRD and XPS characterization, we have confirmed that an excess amount of H2 in the reaction bulk leads to the deep hydrogenation of the furan ring while an insufficient amount of H2 leads to the formation of Ni3N and the deactivation of the catalyst.

A series of cobalt-based catalysts supported on several acidic/basic oxides were prepared by the incipient wetness impregnation method and applied for the one-pot synthesis of isophorone diamine (IPDA) from hydroamination of isophorone nitrile (IPN). The effects of the supports and cobalt loading on the performance of the catalysts were investigated. The results showed that the Co/SiO2 catalyst with 20 wt % Co loading gave the highest conversion of IPN (90.9%) and yield of IPDA (70.4 mol %) among the supported cobalt catalysts used in this work, and it could be reused eight times without a significant decrease in the catalytic performance, which was much better than that from the commercial Raney Co. Meanwhile, the possible intermediates and reaction pathways during hydroamination of IPN were provided.

We have developed an effective route for obtaining 5-hydroxymethylfurfural with a yield of 92.6 mol% from the dehydration of fructose in N,N-dimethylformamide using a mixture of AlCl3, H2SO4 and H3PO4 as catalyst. The NMR analysis showed the intermediate formed among fructose, AlCl3 and H3PO4 plays an important role in the novel result.

As more and more novel catalyst systems are being developed for the dehydration of carbohydrates, especially glucose, an effective way to separate the dehydration product 5-hydroxylmethylfurfural (5-HMF) is also required for industrial manufacturing. In this paper, for the first time, we have developed a process called EIVRD (entrainer-intensified vacuum reactive distillation) to separate 5-HMF from the dehydration solutions of carbohydrates catalyzed by a metal chloride/1-methyl-3-octyl imidazolium chloride ([OMIM]Cl) ionic liquid, in which high vacuity and entrainers were applied to intensify the distillation of 5-HMF as well as the dehydration of fructose or glucose. In such an EIVRD process, the average recoveries of 5-HMF dehydrated from fructose and glucose are around 93% and 88%, respectively. The recycling of the catalyst system in the EIVRD process is so convenient that the recovery and actual yield of 5-HMF is successfully repeated during the whole five recycled reactions.

Several water-stable ionic liquids with different acidity and affinity were synthesized and applied as both solvents and acid catalysts for Fischer esterification of ethanol reacting with four aliphatic carboxylic acids (acetic acid, n-hexanoic acid, lauric acid, and stearic acid). Among the studied ionic liquids, [(n-bu-SO3H) MIM][HSO4] (3-butyl-1-(butyl-4-sulfonyl) imidazolium sulfate) and [(n-bu-SO3H) MIM][p-TSO] (3-butyl-1-(butyl-4-sulfonyl) imidazolium toluenesulfonate) show higher reactivity for the production of ethyl esters. The catalytic activities of these ionic liquids are strongly dependent on the acidity of their anions and cations, as well as their hydrophilicity and affinity with the reactants. Water refluxing through the condenser may be another important reason for obtaining high conversion of esterification, indicating a water-sequester process is still needed in order to obtain a higher yield of ester in the ionic liquid catalyzed esterification system. Kinetics studies show the conversions of the acids increase with reaction temperature and time, and reach equilibrium within about two hours. The apparent activation energies are 39.1±2.0, 49.7±2.5, 51.4±2.5 and 59.3±3.0 kJ·mol−1 for the formation of ethyl acetate, ethyl n-hexanoate, ethyl laurate and ethyl stearate, respectively.

Alcoholysis of soybean isoflavone glucosides by butanol catalyzed by acidic ionic liquids was studied. The effects of the ionic liquid catalyst type, catalyst concentration, reaction time and reaction temperature on glycoside conversions, and aglycons yields were investigated. The optimum reaction conditions are found to be as follows: 0.036 g mL−1 of ionic liquid [BIM]HSO4 as catalyst, reaction temperature at 104±1°C, reaction time of 100 min. Under these optimum reaction conditions near complete conversions of the three kinds of glycosides (daidzin, glycitin and genistin) are obtained. Furthermore, the kinetics parameters for the alcoholysis were estimated. The activation energies of alcoholysis for the three kinds of isoflavone glucosides are 124 kJ mol−1, 67 kJ mol−1 and 115 kJ mol−1, respectively.