Preparation of hierarchical mesoporous Zn/HZSM-5 catalyst and its application in MTG reaction

The hierarchical mesoporous Zn/ZSM-5 zeolite catalyst was prepared by NaOH treatment and Zn impregnation, and its application in the conversion of methanol to gasoline (MTG) was studied. N2 adsorption-desorption results showed that the mesopores with sizes of 2–20 nm in HZ5/0.3AT was formed by 0.3 M NaOH alkali treatment. The zeolite samples after modification were also characterized by XRF, AAS, XRD, SEM and NH3-TPD methods. Zn impregnated catalyst Zn/HZ5/0.3AT exhibited dramatic improvements in catalytic lifetime and liquid hydrocarbons yield. The selectivity of aromatic hydrocarbons was also improved after Zn impregnation. It is suggested that the mesopores of Zn/HZ5/0.3AT enhanced the synergetic effect of Zn species and acid sites and the capability to coke tolerance, which were confirmed by the results of catalytic test and TGA analysis, respectively.     

Correlation between hydrocarbon distribution and water-hydrocarbon ratio in Fischer-Tropsch synthesis

In order to shorten the evaluation cycle of cobalt catalyst before the optimized catalyst is fixed on, a mathematical method is proposed to calculate weight percentage of C5+ hydrocarbons. Based on the carbide polymerization mechanism and the main hydrocarbons being linear alkanes and α-olefins, the correlation between hydrocarbon distribution and the molecular mass ratio of water to hydrocarbons is discussed. The result shows the ratio was within the range of 1.125-1.286 and the lower the ratio, the more gaseous hydrocarbons were obtained. Moreover, a linear equation between the weight percentage of C5+ hydrocarbons and the weight ratio of C5+ hydrocarbons to the total water is established. These results are validated by corresponding experiments. The weight percentage of C5+ hydrocarbons could be immediately calculated by this linear equation without detailed gas chromatography (GC) analysis of them.     

Crystal Structure and Conformation of [1-(β-D-lyxofuranosyl)uracil]- 2''''-spiro-5"-[4"-(S)-(diethoxyphosphinyl)-2"-oxazoline]

1 INTRODUCTION It is well known that natural and modified nucleosides have potential antiviral and anticancer activities[1,2]. These observations prompted us to synthesize the title compound －a new kind of spironucleoside, whose structure was determined by 1HNMR, 31PNMR and elemental analysis. The configuration was assigned by means of nuclear Overhauser effect. To further confirm the structure and configuration unambiguously, the title compound was subjected to X-ray diffractio…     

Nickel and potassium co-modified β-Mo2C catalyst for CO conversion

Nickel and potassium co-medified β-Mo2C catalysts were prepared and used for CO hydrogenation reaction. The major products over β-Mo2C were C1-C4 hydrocarbons, only few alcohols were obtained. Addition of potassium resulted in remarkable selectivity shift from hydrocarbons to alcohols at the expense of CO conversion over β-Mo2C. Moreover, it was found that potassium enhanced the ability of chain propagation with a higher C2+OH production. Modified by nickel, β-Mo-2C showed a relatively high CO conversion, however, the products were similar to those of pure β-Mo2C. When co-modified by nickel and potassium,β-Mo2C exhibited high activity and selectivity towards mixed alcohols synthesis, and also the whole chain propagation to produce alcohols especially for the stage of C1OH to C2OH was remarkably enhanced. It was concluded that the Ni and K had, to some extent, synergistic effect on CO conversion.     

Nickel and potassium co-modified β-Mo2C catalyst for CO conversion

Nickel and potassium co-modified -Mo2C catalysts were prepared and used for CO hydrogenation reaction. The major products over -Mo2C were C1–C4 hydrocarbons, only few alcohols were obtained. Addition of potassium resulted in remarkable selectivity shift from hydrocarbons to alcohols at the expense of CO conversion over -Mo2C. Moreover, it was found that potassium enhanced the ability of chain propagation with a higher C2+OH production. Modified by nickel, -Mo2C showed a relatively high CO conversion, however, the products were similar to those of pure -Mo2C. When co-modified by nickel and potassium, -Mo2C exhibited high activity and selectivity towards mixed alcohols synthesis, and also the whole chain propagation to produce alcohols especially for the stage of C1OH to C2OH was remarkably enhanced. It was concluded that the Ni and K had, to some extent, synergistic effect on CO conversion.     

NMR Studies on the Subacute Biochemical Effects of Aristolochic Acid on Rat Serum

The subacute effect of aristolochic acid （AA） on rat serum was studied by NMR method. The biochemical effects induced by AA were characterized by an increase in the amounts of creatinine, trimethylamine N-oxide, acetoacetate, acetate and 3-D-hydroxybutyrate and lactate in serum from ^1H NMR spectra. Principal component analysis was used for further comparing the similarities of ^1H NMR spectral profiles of serum from rats treated with AA and model toxins.     

Liquid-liquid interfacial tension of equilibrated mixtures of ionic liquids and hydrocarbons

Ionic liquids are possible alternative solvents for the separation of aromatic and aliphatic hydrocarbons by liquid-liquid extrac- tion. Interfacial tension is an important property to consider in the design of liquid-liquid extraction processes. In this work, the liquid-liquid interfacial tension and the mutual solubility at 25 °C have been measured for a series of biphasic, equilibrated mixtures of an ionic liquid and a hydrocarbon. In particular, the ionic liquids 1-alkyl-3-methylimidazolium bis(trifluorome- thanesulfonyl)imide (with the alkyl substituent being ethyl, hexyl or decyl), 1-ethyl-3-methylimidazolium ethylsulfate, and 1-ethyl-3-methylimidazolium methanesulfonate have been selected, as well as the hydrocarbons benzene, hexane, ethylben- zene, and octane. The selected sets of ionic liquids and hydrocarbons allow the analysis of the influence of a series of effects on the interfacial tension. For example, the interfacial tension decreases with an increase in the length of the alkyl substituent chain of the cation or with an increase of the degree of charge delocalisation in the anion of the ionic liquid. Also, the interfa- cial tension with the aromatic hydrocarbons is markedly lower than that with the aliphatic hydrocarbons. A smaller effect is caused by variation of the size of the hydrocarbon. Some of the observed trends can be explained from the mutual solubility of the hydrocarbon and the ionic liquid.     

SYNTHESIS OF HYDROCARBONS FROM CO_2 AND H_2 OVER Fe/C CATALYST

The production of hydrocarbons by hydrogenation of CO_2 is one ofthe most challenging aims in C_1 chemistry. In this work, we studiedCO_2 hydrogenation over iron catalyst supported on carbon under differentreaction conditions. The products of CO_2 hydrogenation on Fe/C catalyst weremainly hydrocarbons including more than 70% C_2~+ hydrocarbons. When thereaction temperature and pressure were elevated,the CO_2 conversion and theselectivity to hydrocarbon(HC) products increased. It was also found that theaddition of Cu onto Fe/C catalyst has an apperent effect on the activity andselectivity of Fe/C catalyst. It increased the CO_2 conversion and the selectivityto total HC Products to 62.8% and 100% respectively. The results obtainedfrom TPR and M(?)ssbauer spectroscopy proved that the iron was reduced mucheasier in Fe-Cu/C than in the Fe/C catalyst.     

Relationship between the Biodegradability and Structure of Polycyclic Aromatic Hydrocarbons

21 Physicochemical and quantum chemical parameters of 17 kinds of polycyclic aromatic hydrocarbons were calculated by using semi-empirical MOPAC AM1 method. By means of Partial Least Squares （PLS）, quantitative structure-biodegradation relationship （QSBR） study was performed with the logarithm of specific biodegradation rates （logKb）. The optimal model was obtained, and the result showed that the first-order molecular connectivity index （^1X）, the energy of the lowest unoccupied molecular orbital （Elumo）, logarithm of n-octyl alcohol/water partition coefficient （logP） and torsion energy （Et） are the dominant factors governing the biodegradability of polyeyelie aromatic hydrocarbons, and the effect of second-order valence molecular connectivity index （^2X^V）, the third-order valence molecular connectivity index （^3X^V） and molar refractivity （Rm） should not be ignored.     

SYNTHESIS OF 1H，1′H BIS（BENZ—Δ^4—IMIDAZ—OLINE）2,2′—SPIRO—TITANIUM DICHLORIDE

New model compound 1H,1′H-Bis（benz-Δ^4-imidazoline)2,2′-spiro-titanium dichloride was prepared and the structure of the compound was determined by 1R,MS and elementary analysis.     

STRUCTURAL STUDIES OF SNAKE INSULIN CRYSTALS——X-RAY CRYSTALLOGRAPHIC ANALYSIS OF SINGLE CRYSTALS

On the basis of the isolation and crystallization of snake (Zaocys dhumnades dhumna-des, Cantor) insulin, single crystals suitable for X-ray analysis were obtained in citrate buf-fer by micro-method of super-saturation. Resolution of diffraction by the crystal was over4 A, X-ray crystallographic analysis showed that the crystal was cubic with α=67.31 A, itsspace group was P4_232 and each asymmetric unit contained one molecule of snake insulin.The possible packing of hexamers and the orientation of monomers in the unit cell of snakeinsulin crystal were discussed.     

SYNTHESIS AND CHARACTERIZATION OF HYDROPHOBIC-HYDROPHILIC MULTIBLOCK COPOLYMERS FOR BIOMEDICAL APPLICATIONS*

The synthesis and characterization of amphiphilic copolymers of poly(dimethyl siloxane)(PDMS),poly(ethylene oxide)(PEO), and heparin(Hep) were investigated. These multiblock copolymers wereidentified using ~1H-NMR, FTIR, end group analysis, and sulfur elemental analysis. The multiblockcopolymers were characterized by using DSC and X-ray diffractometry. The glass transition temperature,crystalline melting characteristics, annealing effect, and cold crystallization of the block copolymers weredetermined by DSC. The crystallinity of the block copolymers was also determined by X-ray diffractionmethod.     

A molecularly imprinted polymer receptor for the enantiomeric recognition of amino acid hydantoins mimicking cooperative hydrogen bonds between nucleotide bases

Using acrylamide as hydrogen bonding functional monomer and (5R)-5-benzylhydantoin as template, a molecularly imprinted polymer was prepared in a polar solvent, which exhibited good enantiomeric recognition properties. The binding characteristics and selectivity of the polymer were evaluated by batch methods. Scatchard analysis showed that two classes of binding sites were produced in the polymer matrix and their dissociation constants were calculated to be 3.5 × 10-5mol/L and 4.3 ×10-4 mol/L, respectively, by utilizing the model of multiple independent classes of binding sites. These results were more reasonable than those obtained by Scatchard analysis , which was in agreement with the prediction of the binding characteristics of the polymer by exploring the effect of acrylamide on UV spectra of (5R)-5-benzylhydantoin. The substrate- and enantio-selectivity of the polymer was investigated. Finally, the study of effect of water on the chiral separation factor of the polymer further proved that the hy     

Analysis of the suspension polymerization flows of polyvinyl chloride with the exergy analysis involving resource utilization and environmental influence

In order to comprehensively assess the resource utilization of a process system and its influence on the environment, the application range of the traditional exergy analysis was expanded in this paper to include the pollution degree of the discharged wastes to the environment. So technology indexes can be obtained to comprehensively assess the resource utilization and the environment impact of a process system. The harm coefficient and effect coefficient were introduced to concern the different harm to the environment of the different wastes and the pollution effect relative to resource waste by environment. The determination method of the harm coefficient and effect coefficient was discussed. Two suspension polymerization flows of polyvinyl chloride were calculated with this method. The results show that the method can comprehensively assess the resource utilization and the environment impact of the chemical process system by comparing and analyzing.     

The optimum conditions for methanol conversion to dimethyl ether over modified sulfated zirconia catalysts prepared by different methods

Sulfated zirconia (SZ) and two promoted 1%Mn/SZ catalysts which have been prepared via sol gel (Mn/SZ-S) and impregnation (Mn/SZ-I) methods were studied.The morphology of the catalysts was characterized by XRD,BET,NH_3-TPD,ICP,SEM and FT-IR analysis.The conversion of methanol to dimethyl ether and hydrocarbons was carried out in the temperature range of 120-300 ℃.The Mn/SZ-S showed the highest activity due to the high surface area with suitable acidity.The optimum condition of Mn/SZ-S catalyst was investigated at 200°C and LHSV of 0.02 h~(-1) in a time range from 30 to 210 min.It was found that the total conversion decreased from 80.18% to 53.26% at 210 min.The reusability of this catalyst was studied at the optimum condition up till four cycles for 1 h.The characterization of the reused catalyst showed a significant change in the structure and surface acidity due to the blockage of the surface acid sited by carbonaceous materials.     

Investigation of Isomerization of 2—Seleno—1,3,2—diazaphospholidine Derivatives

For the first time the isomerization of 1,3,2-diazaphospholidine-2-sclenide dervatives in refluxing benzene in the presence of trace water was observed. The structures of isomerized products were determined by IR, ^1H NMR,^31P NMR, elemental analysis and X-ray crystallography. The mechanism of isomerization was also proposed.     

ELECTROCHEMICAL COPOLYMERIZATION OF 3-（4-FLUOROPHENYL）THIOPHENE AND 3-METHYLTHIOPHENE IN BORON TRIFLUORIDE DIETHYL ETHERATE

The copolymer poly（3-（4-fluorophenyl）thiophene-co-3-methylthiophene） was successfully prepared from mixtures of 3-（4-fluorophenyl）thiophene （FPT） and 3-methylthiophene （MET） via electrochemical oxidation in boron trifluoride diethyl etherate （BFEE） and its mixed electrolytes with acetonitrile （ACN）. The influence of monomer concentration ratios on the copolymerization was investigated by using linear sweep voltammetry and cyclic voltammetry. The structure and morphology of these copolymer films were elucidated by UV-Vis, infrared spectroscopy, elemental analysis, thermal analysis and scanning electron microscopy （SEM）, respectively. The results showed that the molar ratio of FPT and MeT units, when copolymer was electrodeposited from feed ratio of FPT：MeT = 1：2, was about 1.08：1. In addition, the introduction of ACN into BFEE has little effect on the properties of as-formed copolymers.     

Catalysis Conversion Methane into C2 Hydrocarbons via Electric Field Enhanced Plasma

In this paper the effect of catalyst and carrier in electric field enhanced plasma on methane conversion into C2 hydrocarbons was investigated. Methane coupling reaction was studied in the system of continuous flow reactor on Ni, MoO3, MnO2 catalysts and different ZSM-5 carriers. The per pass conversion of methane can be as high as 22%, the selectivity of ethylene can be as high as 23.8%, of acetylene 60.8%, of ethane 5.4% and of total C2 hydrocarbons was more than 90%. ZSM-5-25 was the better carrier and MnO2 was the better active component. The efficiency of energy was as high as 7.81%.