Highly selective ethylbenzene production through alkylation of dilute ethylene with gas phase-liquid phase benzene and transalkylation feed

A novel industrial process was designed for the highly selective production of ethylbenzene. It comprised of a reactor vessel, vapor phase ethylene feed stream, benzene and transalkylation feed stream. Especially the product stream containing ethylbenzene was used to heat the reactor vessel, which consisted of an alkylation section, an upper heat exchange section, and a bottom heat exchange section. In such a novel reactor, vapor phase benzene and liquid phase benzene were coexisted due to the heat produced by isothermal reaction between the upper heat exchange section and the bottom heat exchange section. The process was demonstrated by the thermodynamic analysis and experimental results. In fact, during the 1010 hour-life-test of gas phase ethene with gas phase-liquid phase benzene alkylation reaction, the ethene conversion was above 95%, and the ethylbenzene selectivity was above 83% （only benzene feed） and even higher than 99% （benzene plus transalkylation feed）. At the same time, the xylene content in the ethylbenzene was less than 100 ppm when the reaction was carried out under the reaction conditions of 140-185℃ of temperature, 1.6-2.1 MPa of pressure, 3.0-5.5 of benzene/ethylene mole ratio, 4-6 v% of transalkylation feed/（benzene＋transalkylation feed）, 0.19-0.27 h^-1 of ethene space velocity, and 1000 g of 3998 catalyst loaded. Thus, compared with the conventional ethylbenzene synthesis route, the transalkylation reactor could be omitted in this novel industrial process.

OES study of the gas phase during diamond films deposition in high power DC arc plasma jet CVD system

This paper used optical emission spectroscopy （OES） to study the gas phase in high power DC arc plasma jet chemical vapour deposition （CVD） during diamond films growth processes. The results show that all the deposition parameters （methane concentration, substrate temperature, gas flow rate and ratio of H2/Ar） could strongly influence the gas phase. C2 is found to be the most sensitive radical to deposition parameters among the radicals in gas phase. Spatially resolved OES implies that a relative high concentration of atomic H exists near the substrate surface, which is beneficial for diamond film growth. The relatively high concentrations of C2 and CH are correlated with high deposition rate of diamond. In our high deposition rate system, C2 is presumed to be the main growth radical, and CH is also believed to contribute the diamond deposition.

DFT Study on the Os^+-catalytic Reduction Reaction of N_2O with H_2 in the Gas Phase

The Os＋-catalytic reduction of N2O by H2 in gas phase has been theoretically investigated with B3LYP method.The reaction mechanisms on the sextet and quartet surfaces were found to be similar.The calculated sextet potential energy profiles show that the two reactions involved in the catalytic cycle,Os＋ ＋ N2O → OsO＋ ＋ N2 and OsO＋ ＋ H2 → Os＋ ＋ H2O,have barriers of 28.3 and 123.3 kJ/mol,respectively.In contrast,the reactions on the quartet surfaces are energetically much more favorable.These results rationalize the experimentally observed low catalytic reactivity of sextet（ground-state） Os＋.Further,the crossing between the sextet and quartet surfaces are also suggested and qualitatively discussed.

Gas Phase Selective Catalytic Oxidation of Toluene to Benzaldehyde on V_2O_5-Ag2O/η-Al_2O_3 Catalyst

Gas phase selective catalytic oxidation of toluene to benzatdehyde was studied on V_2O_5-Ag_2O/η-Al_2O_3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM, and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V+Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No. 4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzaldehyde were higher than those on the undoped catalyst. This was attributed to the disordered structure of V_2O_5 lattice of the K-doped catalyst and a better interracial contact between the particles.

Monte Carlo Simulation of Electron Velocity Distribution and Gas Phase Process in Electron-Assisted Chemical Vapor Deposition

The gas phase process of diamond film deposition from CH4/H2 gas mixture by electron-assisted chemical vapor deposition is simulated by the Monte-Carlo method. The electron velocity distribution under different E/P (the ratio of the electric field to gas pressure) is obtained, and the velocity profile is asymmetric. The variation of the number density of CH3 and H with different CH4 concentrations and gas pressure is investigated, and the optimal experimental parameters are obtained: the gas pressure is in the range of 2.5 kPa - 15 kPa and the CH4 concentration is in the range of 0.5% - 1%. The energy carried by the fragment CH3 as the function of the experiment parameters is investigated to explain the diamond growth at low temperature. These results will be helpful to the selection of optimum experimental conditions for high quality diamond films deposition in EACVD and the modeling of plasma chemical vapor deposition.

First Step in Dissociation Process in the Gas Phase for Small Molecules with Neutral Atoms: Application with the Even-Odd Rule and a Specific Periodic Table for Organic and Inorganic Atoms

Dissociations in the gas phase of small molecules have been intensively studied and dissociation energies of various gases are available in reference works. Configurations of compounds before and after the dissociation are usually known, but local charges are not defined. Building on the even-odd rule, the topic of a series of previous articles by the same author, the objective of this paper is to show how it can be used to give electronic rules for dissociations in gases. To this end, a specific periodic table is created and used. The rules are applied to a selection of more than 30 common molecules, showing that the even-odd rule and its consequences are useful in explaining the phenomenon of dissociation in gases.

Gas Phase Polymerisation of Ethylene with Supported Titanium-Nickel Catalysts

A new ditransition-metal catalyst system TiC1.-NiC1_2,/MgC1_2,-SiO_2,/AlR_3 was prepared. Gas phase polymerization of ethylene with the catalysts has been studied. The kinetic curves of gas phase polymerization showed a decline. The catalysts efficiency and polymerization reaction rates have a optimum value when Ni content of the catalysts was 12.5%(mol).The products obtained are branched polyethylene.

Preparation of Ultrafine Si Powders from SiH_4 by Laser-induced Gas Phase Reaction

High quality ultrafine Si powders have been synthesized from SiH4 by laser induced gas phase reaction. The powders prduced under different synthesis conditions have mean particle size of 10-120nm in diam. with narrow particle size distribution, and free of hard agglomerates.The powders are polycrystalline with the ratio of mean grain to particle diameter being between 0.3-0.7. The size of the powder increases with increasing laser power and reaction pressure,but decreases with increasing silane gas flow rate and the addition of Ar diluent. Grain sizes drop distinctly with the rise of the addition of Ar gas and laser power, but change little with the gas flow rate and reaction temperature. The formation of Si particles under different synthesis conditions is discussed

Diagnosis of gas phase near the substrate surface in diamond film deposition by high-power DC arc plasma jet CVD

Optical emission spectroscopy （OES） was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition （CVD）. C2 radical was determined as the main carbon radical in this plasma atmosphere. The deposition parameters, such as substrate temperature, anode-substrate distance, methane concentration, and gas flow rate, were inspected to find out the influence on the gas phase. A strong dependence of the concentrations and distribution of radicals on substrate temperature was confirmed by the design of experiments （DOE）. An explanation for this dependence could be that radicals near the substrate surface may have additional ionization or dissociation and also have recombination, or are consumed on the substrate surface where chemical reactions occur.

Comparison between Spectrophotometry and Gas Phase Molecular Absorption Spectrometry for Determination of Nitrite Nitrogen in Flue Gas

Spectrophotometry and gas phase molecular absorption spectrometry for determination of nitrite nitrogen in flue gas were compared.KOH absorption solution was used to absorb nitrite nitrogen in flue gas,and the concentration of nitrite nitrogen in the absorption solution was determined by spectrophotometry and gas phase molecular absorption spectrometry to obtain the concentration of nitrite nitrogen in flue gas.The experiments show that both methods are accurate and reliable.

Gas‐phase fluorination of conjugated microporous polymer microspheres for effective interfacial stabilization in lithium metal anodes

Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to the growth of Li dendrites and the degradation of active electrodes.Herein,we directly fluorinate alkyne-containing conjugated microporous polymers(ACMPs)microspheres with fluorine gas(F_(2))to introduce a novel fluorinated interlayer as an interfacial stabilizer in lithium metal batteries.Using density functional theory methods,it is found that as-prepared fluorinated ACMP(FACMP)has abundant partially ionic C–F bonds.The C–F bonds with electrochemical lability yield remarkable lithiophilicity during cycling.The in situ reactions between the active C–F bonds and Li ions enable transfer of lithium fluoride microcrystals to the solid electrolyte interphase(SEI)layers,guaranteeing effective ionic distribution and smooth Li deposition.Consequently,Li metal electrodes with the fluorinated interlayers demonstrate excellent cycling performances in both half-batteries and full cells with a lithium bis(trifluoromethanesulfonyl)imide electrolyte as well as a nonfluorinated lithium bis(oxalate)borate electrolyte system.This strategy is highly significant in customizable SEI layers to stabilize electrode interfaces and ensure high utilization of Li metal anodes,especially in a nonfluorinated electrolyte.

Important mesoscale phenomena in gas phase fluidized bed ethylene polymerization

Gas phase fluidized bed processes have been widely applied to polyethylene production.In these processes,the flow,mass transfer,and reaction rate on the microscale and macroscale are strongly coupled because of the multiphase and multiscale nature of the fluidization system.Understanding mesoscale phenomena is therefore essential to the quantitative translation of the knowledge obtained from the microscale to the macroscale.This paper reviews the development of ethylene polymerization gas phase processes while focussing on studies regarding mesoscale phenomena.These include experimental characterizations,mathematical modelling and control strategies.Trends and future developments in this field are also discussed.

Study on the Gas Phase Stability of Heme-binding Pocket in Cytochrome Tb_5 and Its Mutants by Electrospray Mass Spectrometry

To elucidate the effect of various amino acid residues on the heme-binding pocket in cytochrome Tb 5, several residues were chosen for replacement by means of site-directed mutagenesis. Comparison of the mass spectrum between the F35Y mutant and the wild type shows that the relative abundance of holo-protein ion of F35Y is lower than that of the wild type in gas phase. It is concluded that mutation from Phe35 residue to tyrosine decreases the hydrophobic character of cytochrome Tb 5 heme pocket, which decreases the stability of heme-binding pocket. ESI-MS spectra of the mutants V61E, V61K, V61H and V61Y show various contribution of amino acid to the stability of heme-binding pocket. The small and non-polar residue Val61 was replaced with large or polar residues, resulting in enhancing the trend of heme leaving from the pocket. In addition, comparison of the mass relative abundance of holo-proteins among all the Val61-mutants, shows that their stability in gas phase appropriately submit the following order: wild type>V61H>V61E>V61K≈V61Y. The extra great stability of quadruple sites mutant E44/48/56A/D60A shows that reduction of electrostatic or hydrogen bond interactions among the residues locating in the outside region of the heme edge remarkably affect the stability of heme. The results of analyzing the oxidation states of heme iron in Tb 5 and its mutants by in-source-CAD experiment suggest that the charge states of heme iron maintain inflexible in mutation process

Retention behaviors of novel ionic liquid stationary phases and their selectivity for capillary gas chromatography

One chloride-terminated ionic liquid（CTIL） and two hydroxyl-terminated ionic liquids（HTILs） were synthesized and used as stationary phases for capillary gas chromatography（CGC）.Molecular interactions of these stationary phases were evaluated by Abraham solvation parameter model,indicating that the CTIL exhibits remarkably strong H-bond basicity and the HTILs possess both H-bond basicity and acidity.The molecular interactions were further confirmed by separation of a complex mixture consisting of ketones,aldehydes,esters,alcohols and aromatic compounds.It was found that the obtained solvation parameters correlate well with the chromatographic performances of the analytes in terms of elution order and resolution.The well correlated relationship between the solvation parameters and the selectivity of the CTIL and HTILs stationary phases is quite helpful in predicting and understanding the retention behaviors of different types of analytes on these stationary phases.

Control Factors and Diversities of Phase State of Oil and Gas Pools in the Kuqa Petroleum System

Based on the analysis of the hydrocarbon geochemical characteristics in the Kuqa petroleum system of the Tarim Basin, this study discusses the causes and controlling factors of the phase diversities and their differences in geochemical features. According to the characteristics and differences in oil and gas phase, the petroleum system can be divided into five categories： oil reservoir, wet gas reservoir, condensate gas-rich reservoir, condensate gas-poor reservoir and dry gas reservoir. The causes for the diversities in oil and gas phases include diversities of the sources of parent material, maturity of natural gas and the process of hydrocarbon accumulation of different hydrocarbon phases. On the whole, the Jurassic and Triassic terrestrial source rocks are the main sources for the hydrocarbon in the Kuqa Depression. The small differences in parent material may cause diversities in oil and gas amount, but the impact is small. The differences in oil and gas phase are mainly affected by maturity and the accumulation process, which closely relates with each other. Oil and gas at different thermal evolution stage can be captured in different accumulation process.

An Excellent Gas Chromatographic Stationary Phase for Separation of Phenol and Cresol Isomers--Heptakis(2,6-di-O-pentyl-3-O-allyl)-β-Cyclodextrin

Heptakis(2.6-di-O-pentyl-3-O-ally)-β-cyclodextrin as an excellent gas chromatographic stationary phase separating phenol and cresol isomers is described.

A NOVEL DERIVATIVE OF β-CYCLODEXTRIN AS CHIRAL SIATIONARY PHASE IN CAPILLARY GAS CHROMATOGRAPHY

A novel β-cyclodextrin derivative, 2, 6-di-O-butyl-3-O-acetyl-β-cyclodex- trin, was prepared and used as chiral stationary phase for capillary gas chromato- graphic resolution of enantiomers, lhe glass capillary columns with the derivative having low melting point and high thermal stability could produce more than 3000 plates per column meter and have proven to be good chlral columns to separate the enantiomers of some amino acids, derivatives of epoxy ethane and alkyl halide, etc.

The Gas Nucleation Process Study of Anatase TiO_2 in Atmospheric Non-Thermal Plasma Enhanced Chemical Vapor Deposition

Abstract The gas phase nucleation process of anatase TiO2 in atmospheric non-thermal plasma enhanced chemical vapor deposition is studied. The particles synthesized in the plasma gas phase at different power density were collected outside of the reactor. The structure of the collected particles has been investigated by field scanning electron microscope （FESEM）, X-ray diffraction （XRD）, high resolution transmission electron microscopy （HRTEM） and selected area electron diffraction （SAED）. The analysis shows that uniform crystalline nuclei with average size of several nanometers have been formed in the scale of micro second through this reactive atmo- spheric plasma gas process. The crystallinity of the nanoparticles increases with power density. The high density of crystalline nanonuclei in the plasma gas phase and the low gas temperature are beneficial to the fast deposition of the 3D porous anatase TiO2 film.

In-situ Formation of MgAl_(2)O_(4):A Method of Tailoring Microstructure and Properties for Development of High-performance Refractories

The in-situ formation mechanism of MgAl_(2)O_(4) was introduced,focusing on the formation process by solid phase reaction and gas phase reaction as well as the phenomenon of secondary spinelization.The influencing factors of the in-situ MgAl_(2)O_(4) formation and its effect on the microstructure and the properties of materials were systematically summarized for the Al2O3-MgO-MgAl_(2)O_(4) system and the carbon-containing refractories systems.It was pointed out that the in-situ formation of MgAl_(2)O_(4),including secondary spinelization,can regulate the microstructure and the service performance of materials.Its expansion effect can not only offset the shrinkage caused by sintering to improve the corrosion resistance of refractories,but also seriously restrict the reliability of functional refractories.The composition,the particle size,the atmosphere,and the temperature are important factors affecting the in-situ formation of MgAl_(2)O_(4).In the carbon-containing materials systems,the solid-solid reaction and the gas-solid reaction coexist to produce MgAl_(2)O_(4),which provides an effective way to further regulate the microstructure and the properties of materials through the reaction process.

LED照射光催化剂用于苯、甲苯、乙苯和二甲苯分解(英文)

Studies on the use of gas phase applications of light emitting diodes(LEDs) in photocatalysis are scarce although their photocatalytic decomposition kinetics of environmental pollutants are likely different from those in aqueous solutions.The present study evaluated the use of chips of visible light LEDs to irradiate nitrogen doped titania(N-TiO2) prepared by hydrolysis to decompose gaseous benzene,toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene.Photocatalysts calcined at different temperatures were characterized by various analytical instruments.The degradation efficiency of benzene was close to zero for all conditions.For the other compounds,a conventional 8 W daylight lamp/N-TiO2 unit gave a higher photocatalytic degradation efficiency as compared with that of visible-LED/N-TiO2 units.However,the ratios of degradation efficiency to electric power consumption were higher for the photocatalytic units that used two types of visible-LED lamps(blue and white LEDs).The highest degradation efficiency was observed with the use of a calcination temperature of 350 oC.The average degradation efficiencies for toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene were 35%,68%,94%,and 93%,respectively.The use of blue-and white-LEDs,high light intensity,and low initial concentrations gave high photocatalytic activities for the photocatalytic units using visible-LEDs.The morphological and optical properties of the photocatalysts were correlated to explain the dependence of photocatalytic activity on calcination temperature.The results suggest that visible-LEDs are energy efficient light source for photocatalytic gas phase applications,but the activity depends on the operational conditions.