Among many ethylene glycol synthetic methods, the ethylene carbonate route is preferred due to its extremely high EG selectivity and low EC/ H2O ratio. In this work, we synthesized a variety of layered double hydroxides (LDH) and layered double oxides (LDO) by co–precipitation method for the hydrolysis of EC. The Zn3Al–LDO showed the highest catalytic activity under low EC/ H2O ratio and mild conditions, and the EG yield of 93%–99% could be obtained at 100 °C for 3–4 h. It was found that Zn3Al–LDO has larger pore diameter and pore volume than Zn2Al–LDO and Zn4Al–LDO. It could retain a host of base sites in the hydrolysis system because it had no "memory effect". The active sites inhibition experiment proved that Zn3Al–LDO is an acid–base synergistic catalyst and the base sites are dominant. The catalyst can be recycled at least five times with calcination and activation to maintain excellent catalytic activity.
1-Ethyl-3-methylimidazolium bis(oxalato)borate ([Emim][BOB]), a room-temperature ionic liquid, has been prepared and used for the first time to develop new borate-containing material. A new open-framework cobalt borophosphate, (NH(4))(7)Co(4)(H(2)O)[B(2)P(4)O(15)(OH)(2)](2)[H(2)PO(4)][HPO(4)], with peanut shaped extra-large 16-ring channels has been obtained.
The catalytic properties of physical mixtures of Ni particles (100–200 nm) with nanoparticles of anatase TiO2 (TiO2-A), ZrO2, Al2O3, rutile TiO2 (TiO2-R), and CeO2 were investigated for the hydrodeoxygenation (HDO) of guaiacol. High selectivities to phenolics were obtained only for Ni mixed with anatase TiO2 (Ni and TiO2-A), while saturated hydrocarbons were the main products for the mixtures with other supports. By thermal treatment in hydrogen gas only at 300 °C or higher and subsequently separating the large Ni particles from the TiO2-A particles with a magnet, it was further discovered that there was migration of TiO2 from TiO2-A onto the large Ni particles, resulting in an amorphous TiO2 overlayer on the Ni particles as evidenced by high-resolution TEM, and vice versa, migration of Ni onto TiO2-A. The TiO2 overlayer rendered the Ni particles completely inactive as a hydrogenation/hydrodeoxygenation catalyst. Conversely, the small amounts of Ni (<1.5 wt %) migrated onto TiO2-A formed highly dispersed Ni, undetectable by high-resolution TEM (<2 nm), that were remarkably highly active for HDO of guaiacol, producing selectively phenolics. Such highly selective HDO catalysts could also be formed by incipient wetness impregnation of Ni in loadings above 2 wt % onto the TiO2-A, but it was essential to pretreat the sample in H2 at 300 °C or higher. Pretreatment in H2 at 200 °C generated catalysts that produced saturated ring products. The activity of the impregnated catalysts, as measured by guaiacol conversion, increased linearly with Ni loading below 0.5 wt %. The activity continued to increase with Ni loading but more slowly up to 2 wt %, beyond which there was little further change. The results suggested that two types of Ni species existed on the TiO2-A surface. One type consisted of a cluster of Ni atoms that were dominant on larger Ni particles that were active in aromatic ring hydrogenation and hydrodeoxygenation. They were readily covered by reducible TiO2-A at 300 °C or higher due to the traditional strong metal support interaction (SMSI) effect and became inactive. Another type was clusters of a very small number of Ni atoms, perhaps one atom, that were present as highly dispersed Ni clusters interacting strongly with the defect sites of TiO2-A. The strong interaction of this type of Ni with the TiO2 defect deterred TiOx migration allowing surface exposed Ni atoms to catalyze the HDO of guaiacol with very high selectivities that were not characteristic of typical Ni particles.
Humin formation is one of the key issues that hinders economical 5-HMF production from hexose sugars such as glucose and fructose. In this work, the mechanism of humin formation in glucose/fructose conversion to HMF was studied in an ionic liquid system (1-butyl-3-methylimidazolium chloride, [BMIM]Cl) with CrCl3 as the catalyst. Elemental analysis, XRD, FT-IR, and TEM were applied to study the molecular structure and morphology of the solid humins. The possible intermediates to form solid humins were investigated by HPLC-MS. We synthesized furanic model compounds that mimic the experimentally identified humin intermediates to investigate the mechanism of humin growth at an early stage. The results showed that a furan compound bearing a hydroxymethyl and an electron-donating group was unstable due to three types of reactions: (1) bimolecular ether formation reactions; (2) intermolecular addition reaction; (3) furan ring opening reaction with water. The stability of a furan compound in [BMIM]Cl was increased when the hydroxymethyl group of a furan compound was protected by a methyl group, and the stability was further enhanced with an additional electron-withdrawing group (such as an aldehyde group) on the furan ring. Protecting the hydroxymethyl group of 5-HMF with a methyl group allows easy separation of the products from the [BMIM]Cl solvent through extraction.
In this work, 119Sn is used as probe-atom, nd room temperature Mossbauer measurement of Bi1.68Pb0.32Sr1.75Ca1.75Cu2.65-xSnxOy(x=0.2-0.8) sample is performed. Combined with the results of X-ray diffraction and electric characteristic measurement, the relation between the occupancy of Sn in the sample and its electric characteristics is analysed, and an conclusion that squarecoordinated Cu performs a chief influence on the electric characteristic of high-transition-temperature (Tc) phase superconductor is reached.
The activity coefficients at infinite dilution, γi∞, for both polar and nonpolar solutes in the ionic liquid 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM][FAP]) have been determined by gas−liquid chromatography using the ionic liquid as the stationary phase. The measurements were carried out in the temperature range of (313 to 364) K. The partial molar excess enthalpies at infinite dilution HiE,∞ of the solutes in the ionic liquid were also derived from the temperature dependence of the γi∞ values.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
