This numerical study investigates the effects of using a diluted fuel(50% natural gas and 50% N₂)in an industrial furnace under several cases of conventional combustion(air with 21% O₂ at 300 and 1273 K)and the highly preheated and diluted air(1273 K with 10% O₂ and 90% N₂)combustion(HPDAC)conditions using an in-house computer program.It was found that by applying a combined diluted fuel and oxidant instead of their uncombined and/or undiluted states,the best condition is obtained for the establishment of HPDAC's main unique features.These features are low mean and maximum gas temperature and high radiation/total heat transfer to gas and tubes;as well as more uniformity of theirs distributions which results in decrease in NO_x pollutant formation and increase in furnace efficiency or energy saving.Moreover,a variety of chemical flame shape,the process fluid and tubes walls temperatures profiles,the required regenerator efficiency and finally the concentration and velocity patterns have been also qualitatively/quantitatively studied.

Thermophoresis is an important mechanism of micro-particle transport due to temperature gradients in the surrounding medium.It has numerous applications,especially in the field of aerosol technology.This study has numerically investigated the thermophoretic deposition efficiency of particles in a laminar gas flow in a concentric annulus using the critical trajectory method.The governing equations are the momentum and energy equations for the gas and the particle equations of motion.The effects of the annulus size,particle diameter,the ratio of inner to outer radius of tube and wall temperature on the deposition efficiency were studied for both developing and fully-developed flows.Simulation results suggest that thermophoretic deposition increases by increasing thermal gradient,deposition distance,and the ratio of inner to outer radius,but decreases with increasing particle size.It has been found that by taking into account the effect of developing flow at the entrance region,higher deposition efficiency was obtained,than fully developed flow.

Liquid argon flow along a nanochannel is studied using molecular dynamics (MD) simulation in this work.Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) is used as the MD simulator.The effects of reduced forces at 0.5,1.0 and 2.0 on argon flow on system energy in the form of system potential energy,pressure and velocity profile are described.Output in the form of three-dimensional visualization of the system at steady-state condition using Visual Molecular Dynamics (VMD) is provided to describe the dynamics of the argon atoms.The equilibrium state is reached after 16000 time steps.The effects on system energy,pressure and velocity profile due to reduced force of 2.0 (F2) are clearly distinguishable from the other two lower forces where sufficiently high net force along the direction of the nanochannel for F2 renders the attractive and repulsive forces between the argon atoms virtually non-existent.A reduced force of 0.5 (F0.5) provides liquid argon flow that approaches Poiseuille (laminar) flow as clearly shown by the n-shaped average velocity profile.The extension of the present MD model to a more practical application affords scientists and engineers a good option for simulation of other nanofluidic dynamics processes.

The effects of sintering atmosphere on the properties of symmetric TiO₂ membranes are studied with regard to sintering behavior,porosity,mean pore size,surface composition,and surface charge properties.The experimental results show that the symmetric TiO₂ membranes display better sintering activity in the air than in argon,and the mean pore diameters and porosities of the membrane sintered in argon are higher than those of the membrane sintered in the air at the same temperature.The surface compositions of the symmetric TiO₂ membrane sintered in the air and in argon at different temperatures,as studied by X-ray photoelectron spectroscopy,are discussed in terms of their chemical composition,with particular emphasis on the valence state of the titanium ions.The correlation between the valence state of the titanium ions at the surface and the surface charge properties is examined.It is found that the presence of Ti³⁺,introduced at the surface of the symmetric TiO₂ membranes by sintering in a lower partial pressure of oxygen,is related to a significant decrease in the isoelectric point.TiO₂ with Ti⁴⁺ at the interface has an isoelectric point of 5.1,but the non-stoichiometric TiO_2-x with Ti³⁺ at the interface has a lower isoelectric point of 3.6.

Phase separation behavior of cocamidopropyl betaine/water/polyethylene glycol (PEG) system was studied.The effects of concentration and molecular weight of PEG on the phase separation behavior were investigated.Clouding occurred when the concentration of PEG was large enough in the betaine aqueous solution,and the concentration of PEG at cloud point decreased with the increase of PEG molecular weight for a constant betaine concentration.The bottom phase was the PEG-rich phase,and the upper phase was the betaine-rich phase.The volumetric ratio of PEG-rich phase to betaine-rich phase,at the same difference between the PEG concentration and the one at the cloud point,ΔC_cp(0.1 g·ml^-1),decreased as the PEG molecular weight increased and approached 1 for higher PEG molecular weight(about 20000),which was similar to the typical aqueous two-phase system.This volumetric ratio depended on the initial PEG concentration,but independent of PEG molecular weight.The concentration ratio of betaine to PEG in both phases depended on the ΔC_cp,independent of PEG molecular weight.

The instability mechanisms of the supported liquid membrane using Celgard 2500 membranes as support and tributyl phosphate dissolved in kerosene as carrier for phenol transport was studied by electrochemical impedance spectroscopy.Emulsion formation is demonstrated to be one of the main causes for the instability of supported liquid membrane in the present system.The emulsion-facilitated conditions,such as higher membrane liquid concentration,faster stirring speed,lower salt concentration and higher HLB value,would accelerate the degradation of supported liquid membrane.Other mechanisms including solubility and osmotic pressure work together to increase the membrane liquid loss.

The synthesis of methylene diphenyl dimethylcarbamate(4,4'-MDC) from methyl N-phenyl carbonate (MPC) and formaldehyde (HCHO) was conducted in the presence of sulfonic acid-functionalized ionic liquids (ILs) as dual solvent-catalyst.The influences of the kind of anion in the ionic liquids,reaction conditions and the recycle of the ionic liquid on 4,4'-MDC synthesis reaction were investigated.In addition,the acid strength of ILs was determined by the Hammett method with UV-visible spectroscopy,and the acid strength-catalytic activity relationship was correlated.The activity estimation results showed that HSO₃-bmimCF₃SO₃ was the optimal dual solvent-catalyst.Under the suitable reaction conditions of 70℃,40 min,molar ratio of n_MPC/n_HCHO=10/1 and mass ratio of W_ILs/W_MPC=4.5/1,the yield of 4,4'-MDC based on HCHO was 89.9% and the selectivity of 4,4'-MDC with respect to MPC was 74.9%.Besides,[HSO₃-bmim]CF₃SO₃ was reused four times after being purified and no significant loss in the catalytic activity was observed.

The present work contributed to a new developed production method for enhancing the quality of isoamylene (IA) by adding a small amount of tertiary amyl alcohol (TAA) to the catalyst of strong acid cation exchange resin.TAA improved the selectivity of 2-methyl-2-butene (2M2B) at a high conversion level for the isomerization of IA.Compared with the other results from the current IA units,the conversion of 2-methyl-1-butene (2M1B),the mass ratio of 2M2B to 2M1B and the selectivity of 2M2B were increased from 0.5474,7.32 and 0.6864 to 0.72,12 and 0.95,respectively,while the dimers content in the products decreased from 4.38% to below 1.0%.Optimized conditions for IA isomerization consisted of temperature between 28 and 33℃ and system pressure of 0.5 MPa,weight hourly space velocity of 8.0 h^-1 with TAA mass fraction of 0.7%-0.9% in raw material.The results in lab supported bases for the developed process in industrial application which was later proved to be successful.In addition,a possible mechanism of the isomerization process was speculated to propose a key step of water formation in the TAA-added isomerization process and a verified experiment was conducted to support this speculation.

The copper based catalysts,CuO/γ-Al₂O₃,CuO/γ-Al₂O₃-cordierite(Cord) and CuO/Cord,were prepared by impregnation method.The catalytic activity of the catalysts was tested in absence and presence of water vapor,and the catalysts were characterized.Temperature program desorption (TPD) experiments of toluene and water on the catalysts were carried out.The influence of water vapor on the activity of the catalysts was discussed.Results showed that addition of the water vapor has a significant negative effect on the catalytic activity of the catalysts.The higher the concentration of the water vapor in feed steam was,the lower the catalytic activity of the copper based catalysts became,which could be mainly ascribed to the competition of water molecules with toluene molecules for adsorption on the catalyst surfaces.TPD experiments showed that the strength of the interaction between water molecules and three catalysts followed the order:CuO/γ-Al₂O₃>CuO/γ-Al₂O₃-Cord>CuO/Cord.As a consequence of that,the degree of degradation in the catalytic activity of these three catalysts by the water vapor followed the order:CuO/γ-Al₂O₃>CuO/γ-AAl₂O₃-Cord>CuO/Cord.However,the negative effect of the water vapor was reversible.

The esterification reactions of lactic acid with isobutanol and n-butanol have been studied in the presence of acid ion-exchange resin Weblyst D009.The influences of catalyst loading,stirrer speed,catalyst particle size,initial reactant molar ratio and temperature on the reaction rate have been examined.Experimental kinetic data were correlated by using the Pseudo-homogeneous,Langmuir-Hinshelwood and Eley-Rideal models.Nonideality of the liquid phase was taken into account by using activities instead of molar fractions.The activity coefficients were calculated according to the group contribution method UNIFAC.Provided that the nonideality of the liquid is taken into account,the esterification kinetics of lactic acid with isobutanol and n-butanol catalyzed by the acid ion-exchange resin can be described using all three models with reasonable errors.

In this work grand canonical Monte Carlo simulations were performed to study gas separation in three pairs of isoreticular metal-organic frameworks (IRMOFs) with and without catenation at room temperature.Mixture composed of CO₂ and H₂ was selected as the model system to separate.The results show that CO₂ selectivity in catenated MOFs with multi-porous frameworks is much higher than their non-catenated counterparts.The simulations also show that the electrostatic interactions are very important for the selectivity,and the contributions of different electrostatic interactions are different,depending on pore size,pressure and mixture composition.In fact,changing the electrostatic interactions can even qualitatively change the adsorption behavior.A general conclusion is that the electrostatic interactions between adsorbate molecules and the framework atoms play a dominant role at low pressures,and these interactions in catenated MOFs have much more pronounced effects than those in their non-catenated counterparts,while the electrostatic interactions between adsorbate molecules become evident with increasing pressure,and eventually dominant.

In the design of chemical processes,such as catalytic cracking of bitumen and heavy oil,the knowledge of phase behavior at the critical endpoint is essential.Based on the PR equation of state,the algorithm developed by Heidemann and Khalil for calculating critical properties was used to compute critical points.An algorithm for determining the equilibrium phase of the critical point using the tangent plane criterion was developed,and was used to calculate the critical endpoints of different mixtures,including non-polar,polar and associating systems.The critical endpoint,representing the type of the phase behavior,was employed to fit the interaction parameter of mixtures in critical state at high pressure.Lines of critical endpoints for ternary mixtures were also determined with the algorithm.

Density (ρ) and viscosity (η) measurements were carried out for 4-aminobutyric acid in 0.0041,0.0125 and 0.0207 mol·L^-1 aqueous salbutamol sulphate at T=308.15,313.15 and 318.15K.The measured values of density and viscosity were used to estimate some important parameters such as apparent molar volume V_φ,limiting apparent molar volume V_φ⁰ transfer volume △V_φ⁰,hydration number n_H,second derivative of infinite dilution of partial molar volume with temperature ∂²V_φ⁰/∂T²,viscosity B-coefficients,variation of B with temperature dB/dT,free energy of activation per mole of solvent △μ₁^0* and solute △μ₂^0*,activation entropy △S₂^0* and activation enthalpy △H₂^0* of the amino acids.These parameters have been interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.

The pyrolysis mechanisms of quinoline and isoquinoline were investigated using the density functional theory of quantum chemistry,including eight reaction paths and a common tautomeric intermediate 1-indene imine.It is concluded that the conformational tautomerism of the intermediate decides the pyrolysis products(C₆H₆,HC≡C-C≡N,C₆H₅C≡N and HC≡CH)to be the same,and also decides the total disappearance rates of the reactants to be the same,for both original reactants quinoline and isoquinoline during the pyrolysis reaction.The results indicate that the intramolecular hydrogen migration is an important reaction step,which often appears in the paths of the pyrolysis mechanism.The activation energies of the rate determining steps are obtained.The calculated results are in good agreement with the experimental results.

The present work is concerned with determining the viscosity,diffusion,thermal diffusion factor and thermal conductivity of five equimolar binary gas mixtures including:CF₄-He,CF₄-Ne,CF₄-Ar,CF4-Kr,CF₄-Xe from the principle of corresponding states of viscosity by the inversion technique.The Lennard-Jones (12-6) model potential is used as the initial model potential.The calculated interaction potential energies obtained from the inversion procedure is employed to reproduce the viscosities,diffusions,thermal diffusion factors,and thermal conductivities.The accuracies of the calculated viscosity and diffusion coefficients were 1% and 4%,respectively.

Nitrile hydratase (NHase) is an important industrial enzyme used for acrylamide production from acrylonitrile.The deactivation kinetics of NHases in free resting cells of Rhodococcus sp.was presented based on a bi-steady state assumption.Effects of hydration temperature,product concentration and substrate concentration on NHase deactivation were investigated experimentally and correlated with a first order deactivation kinetics.The results showed that the hydration temperature and product concentration were major factors governing the deactivation of NHases under substrate-feeding conditions.When acrylamide concentration was higher than 250 g·L^-1,the deactivation of NHases became serious and the bi-steady state assumption was not applicable.When the hydration temperature was controlled at a relatively higher level such as 28℃,the total deactivation rate constant was about 2.8-fold of that at 20℃.

In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase,α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants,the catalytic properties of bacterial luciferase andα-amylase were assayed,and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low,the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand,the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction,which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However,at high cationic surfactant concentration,the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins,leading to the loss of enzymatic activities.

Levulinic acid is considered as a promising green platform chemical derived from biomass.The kinetics of levulinic acid accumulation in the hydrolysis process of wheat straw was investigated in the study.Using dilute sulfuric acid as a catalyst,the kinetic experiments were performed in a temperature range of 190-230℃ and an acid concentration range of 1%-5% (by mass) .A simple model of first-order series reactions was developed,which provided a satisfactory interpretation of the experimental results.The kinetics of main intermediates including sugar and 5-hydroxymethylfurfural(5-HMF) were also established.The kinetic parameters provided useful information for understanding the hydrolysis process.

In order to enhance phosphorus removal in traditional step-feed anoxic/oxic nitrogen removal process,a modified pilot-scale step-feed anaerobic/anoxic/oxic (SFA²/O) system was developed,which combined a reactor similar to UCT-type configuration and two-stage anoxic/oxic process.The simultaneous nitrogen and phosphorus removal capacities and the potential of denitrifying phosphorus removal,in particular,were investigated with four different feeding patterns using real municipal wastewater.The results showed that the feeding ratios(Q₁)in the first stage determined the nutrient removal performance in the SFA²/O system.The average phosphorus removal efficiency increased from 19.17% to 96.25% as Q₁ was gradually increased from run 1 to run 4,but the nitrogen removal efficiency exhibited a different tendency,which attained a maximum 73.61% in run 3 and then decreased to 59.62% in run 4.As a compromise between nitrogen and phosphorus removal,run 3 (Q₁=0.45Q_total) was identified as the optimal and stable case with the maximum anoxic phosphorus uptake rate of 1.58mg·(g MLSS)^-1·h^-1.The results of batch tests showed that ratio of the anoxic phosphate uptake capacity to the aerobic phosphate uptake capacity increased from 11.96% to 36.85% with the optimal influent feeding ratio to the system in run 3,which demonstrated that the denitrifying polyP accumulating organisms could be accumulated and contributed more to the total phosphorus removal by optimizing the inflow ratio distribution.However,the nitrate recirculation to anoxic zone and influent feeding ratios should be carefully controlled for carbon source saving.

Corrosion behavior of TP316L was investigated with simulated atmosphere and ash deposition for the superheater in biomass boiler.Corrosion dynamic curves were plotted by mass gain.The results showed that the corrosion was dependent on temperature and was greatly accelerated by ash deposition.The mass gain was distinctly reduced in the presence of SO₂ with and without ash deposition on the specimens.Corrosion rates with ash deposit at different temperatures were calculated.Two feasible methods were provided to avoid serious high-temperature corrosion in the biomass boiler.

The porous medium has an important effect on hydrate formation.In this paper,the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system.The results show that A-type zeolite can influence methane hydrate formation.At the temperature of 273.5 K and pressure of 8.3 MPa,the distilled water with A-type zeolite can form methane hydrate with gaseous methane in 12 hours.The formation process of the system with A-type zeolite was quite steady and the amount of A-type zeolite can influence the gas storage capacity significantly.The adding of A-type zeolite with 0.067 g·(g water)^-1 into 2×10^-3 g·g^-1 SDS-water solution can increase the gas storage capacity,and the maximum increase rate was 31%.Simultaneously the promotion effect on hydrate formation of 3A-type zeolite is much more obvious than that of 5A-type zeolite when the water adding amounts are 0.033 g·g^-1 and 0.067 g·g^-1 at the experimental conditions.

An isothermal operation is implemented by employing a thermogravimetric analyzer (TGA) for simulating the thermal decomposition behavior of 58μm pine sawdust in air atmosphere.An independent parallel reaction model is adopted in this study to describe the thermal decomposition mechanism.The Weibull distribution function is used to record and analyze the weight loss during isothermal decomposition at different temperatures(500,600,700,and 800℃).The total weight loss of the pine sawdust is assumed as a linear combination of individual weight loss from three components,including the char and two volatile matters.The plot of the thermal decomposition rate curve leads to kinetic parameters such as the reaction rate constants and the reaction order.The results show that the Weibull distribution function successfully represents decomposition curves of three components,and fits the experimental data very well.Therefore,this study provides a simple way to evaluate the decomposition rate of biomass combustion in a real combustor.

The oxidative desulfurization of a real refinery feedstock (i.e.,non-hydrotreated kerosene with total sulfur mass content of 0.16%) with a mixture of hydrogen peroxide and acetic acid was studied.The influences of various operating parameters including reaction temperature (T),acid to sulfur molar ratio (n_acid/n_S),and oxidant to sulfur molar ratio (n_O/n_S) on the sulfur removal of kerosene were investigated.The results revealed that an increase in the reaction temperature (T) and nacid/nS enhances the sulfur removal.Moreover,there is an optimum n_O/n_S related to the reaction temperature and the best sulfur removal could be obtained at n_O/n_S=8 and 23 for the reaction temperatures of 25 and 60℃,respectively.The maximum observed sulfur removal in the present oxidative desulfurization system was 83.3%.

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of amines and alkenes.After optimizing the reaction conditions,ZnAl-LDHs (3:1) was chosen as the best catalyst for the reaction.The results showed that the catalyst worked very well for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes.Operational simplicity,no solvent,low cost of the catalyst,high yields,reusability,excellent chemoselectivity,wide applicability are the key features of this method.

A flexible fibre biofilm reactor was developed for treatment of organic wastewaters.The hydrodynamic characteristics and mass transfer coefficients of oxygen were studied and compared with those of the conventional activated sludge processes.Tracer experiments were performed to obtain the residence time distributions of the reactors.The results indicated that both reactors could be treated as mixed flow reactors.The effects of flow rates of water and air on the overall mass transfer coefficient of oxygen were investigated,and the correlations between the mass transfer coefficient and the ratio of flow rates were obtained.Compared to the conventional activated sludge reactor,the mass transfer coefficients in the flexible fibre reactor were similar to but slightly lower,and less sensitive to the variation in the ratio of flow rates.It indicated that the fibre packing in the reactor hindered the oxygen transfer to some extent.

The catalytic properties of KF/MgO for the synthesis of didodecyl carbonate (DDC) by transesterification from dimethyl carbonate (DMC) and dodecanol were studied.The effects of loading amount of KF and calcining temperature were systemically investigated.The phase structure was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).Interaction between KF and the carrier MgO occurred in the process of calcination,and a new phase K₂MgF₄ formed when calcining temperature was 673 K or above.FTIR results showed that K₂CO₃ was observed when catalysts calcined in air.When calcining temperature was 873 K and the loading mass amount of KF was 30%,the KF/MgO catalyst exhibited the optimal catalytic properties and the yield of DDC was maximized to 80%.The excellent catalytic properties of KF/MgO was ascribed to the formation of K₂MgF₄+K₂CO₃ during the calcination in air.