Tingzhen Li

Effect of zinc incorporation manner on a Cu–ZnO/Al2O3 glycerol hydrogenation catalyst

A systematic study was undertaken to investigate the effects of zinc incorporation manner on the textural properties, bulk and surface phase compositions, reduction behaviors, and surface acidity of a copper based glycerol hydrogenation catalyst. The catalyst samples were characterized by N2 physisorption, X-ray photoelectron spectroscopy (XPS), X-ray diffraction, transmission electron microscopy, air thermal gravimetric analysis (air-TGA), H2 thermal gravimetric analysis (H2-TGA), and NH3 temperature-programmed desorption. The glycerol hydrogenation performance of the catalysts was studied in a fixed-bed reactor. The characterization results indicated that the zinc promoter incorporated by using the co-precipitation method could improve the dispersion of copper oxide, and decrease the particle size of the copper oxide. The zinc incorporated with the impregnation method is enriched on the catalyst surface. The catalyst prepared by adding zinc using the co-precipitation method provides higher glycerol conversion and 1,2-propanediol selectivity, and lower selectivity to acetol.

Mobility and potential risk of sediment-associated heavy metal fractions under continuous drought-rewetting cycles

Ecological decline in the water level fluctuating (WLF) zone of the Three Gorges Reservoir (TGR) has been well established over the past decades. However, the effect of heavy metal fractions present in the sediment and their potential ecological risk under the anti-seasonal hydrological regime are still unclear. The Pengxi River is a tributary of the Yangtze River and it has a typical annual water level fluctuation ranging from 145 to 175m above sea level. The current study examined heavy metal fractions in sediments containing Cr, Cd, Cu, Pb and Mn collected along the WLF zone using the Tessier sequential extraction scheme. The total organic carbon (TC), total nitrogen (TN), carbon/nitrogen ratio (C/N), pH, particle size composition and content of nitrate (NO3--N), and ammonium (NH4+-N) differed dramatically among the sampled altitudes and depths and was significantly correlated with the flooding time of the WLF zone. At lower altitudes of the WLF zone, the amounts of the exchangeable (EXC), carbonate-bound (CA) and total heavy metal contents of the surface sediment were much higher compared to those of higher altitudes of the WLF zone. The risk assessment code (RAC) for Cd and Mn showed an opposite trend to that of Cr, Cu, and Pb and mainly depended on the organic matter-bound fraction (OM). The modified RAC (mRAC) indicated a very high potential adverse effect for the whole WLF zone, although the risk value was much lower at the lower altitudes and upper depths of the WLF zone. Our results showed that the positive response of the loosely bound fractions (LOS) of heavy metals to the drought-rewetting (DRW) process minimizes the risk of heavy metals in the WLF zone sediment.

SYNTHESIS, CRYSTAL STRUCTURES, AND ANTIBACTERIAL ACTIVITY OF A SERIES OF HYDRAZONE COMPOUNDS DERIVED FROM 4-METHYLBENZOHYDRAZIDE

ABSTRACT A series of hydrazone compounds, 4-methyl- N’ -(4-nitrobenzylidene)benzohydrazide methanol solvate ( 1 ), N’ -(4-hydroxy-3-nitrobenzylidene)-4-methylbenzohydrazide dimethanol solvate ( 2 ), and N’ -(3,5-dibromobenzylidene)-4-methylbenzohydrazide ( 3 ), derived from 4-methylbenzohydrazide with different benzaldehydes, were synthesized and characterized by physico-chemical methods and single crystal X-ray diffraction. Crystals of the compounds are stabilized by intermolecular hydrogen bonds, as well as π···π stacking interactions. Antibacterial activity of the compounds against Staphylococcus aureus , Escherichia coli , and Klebsielle pneumoniae strains was studied. Compounds 1 and 2 have moderate minimum inhibition concentration values on the tested bacteria strains. Compound 3 , with the Br-substituent groups, showed the highest activity on the bacterial strains. Keywords: Synthesis; crystal structure; hydrazone compound; hydrogen bonding; antibacterial activity. 1 INTRODUCTION

Synthesis and structures of two hydrazone compounds derived from 4-methylbenzohydrazide

Two hydrazone compounds N′-(2,4-dichlorobenzylidene)-4-methylbenzohydrazide monohydrate (1) and 2-chloro-5-nitro-N′-(4-methylbenzylidene)benzohydrazide (2) derived from 4-methylbenzohydrazide with different benzaldehydes are synthesized and characterized by physicochemical methods and single crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 4.714(2) Å, b = 13.093(3) Å, c = 24.754(3) Å, V = 1527.9(8) Å3, Z = 4, R1 = 0.0812, and wR2 = 0.1623. Compound 2 crystallizes in the monoclinic space group Cc with unit cell parameters a = 11.564(2) Å, b = 13.271(2) Å, c = 9.462(2) Å, β = 96.860(2)°, V = 1441.7(4) Å3, Z = 4, R1 = 0.0461, and wR2 = 0.0896. The crystals of the compounds are stabilized by intermolecular hydrogen bonds as well as π…π stacking interactions.

Preparation and adsorption performance of hypercrosslinked polymeric adsorbents modified by phenolic hydroxyl group

The hypercrosslinked polystyrene adsorbents of LY-4 and LY-5 were prepared By Friedel-Crafts post-crosslinking reaction with phenol and naphtho. The physical properties of absorbents showed that both phenolic hydroxyl group content and BET surface area of LM-5 are higher than LM-4. Accordingto the adsorption experiment in aqueous solution, the adsorption capacity of aniline onto LM-5 is bigger than that of phenol. The adsorption enthalpies of ΔH for adsorption of phenol (aniline) onto LM-5 are all negative and their absolute values are lower than 40 kJ/mol, which indicate that the adsorption is exothermic process and the physical adsorption is dominant in the adsorption process. Both The Gibbs free energy change of ΔG and adsorption entropy change ΔS of the adsorption are also less than zero which demonstrates that the adsorption is a spontaneous process. The absolute values of ΔH, ΔG and ΔS for adsorption of aniline onto LM-5 is bigger than that of phenol.