Partial oxidation of methane in Ba0.5Sr0.5Co0.8Fe0.1Ni0.1O3-δ ceramic membrane reactor

Ba0.5Sr0.5Co0.8Fe0.1Ni0.1O3δ(BSCFNiO) perovskite oxides were synthesized using a combined EDTA-citrate complexation method,and then pressed into disk and applied in a membrane reactor.The performance of the BSCFNiO membrane reactor was studied for partial oxidation of methane over Ni/α-Al 2 O 3 catalyst.The time dependence of oxygen permeation rate and catalytic performance of BSCFNiO membrane during the catalyst initiation stage were investigated at 850 C.In unsteady state,oxygen permeation rate,methane conversion and CO selectivity were closely related to the state of the catalyst.After 300 min from the initial time,the reaction condition reached to steady state and oxygen permeation rate were obtained about 11.7cm 3 cm 2 min 1.Also,the performance of membrane reactor was studied at the temperatures between 750 and 950 C.The results demonstrated good performance for the membrane reactor,as CH 4 conversion and CO selectivity permeation rate reached 98% and 97.5%,respectively,and oxygen permeation rate was about 14.5 cm 3 cm 2 min 1 which was 6.8 times higher than that of air-helium gradient.Characterization of membrane surface by SEM after reaction showed that the original grains disappeared on both surfaces exposed to the air and reaction side,but XRD profile of the polished surface membrane indicated that the membrane bulk preserved the perovskite structure.     

Preparation and oxygen permeation properties of SrFe（Cu）O3-δ dense ceramic membranes

Mixed oxygen-ionic and electronic conducting membranes of SrFe(Cu)O3−δ were prepared by solid-state reaction method. The crystal structure, oxygen nonstoichiometry, and phase stability of the materials were studied by TGA and XRD. Oxygen permeation fluxes through these membranes were studied at operating temperature ranging from 750 to 950 ℃. Results showed that doping Cu in SrFeO3−δ compound had a significant effect on the formation of single-phased perovskite structure. For SrFe1−xCuxO3−δ series materials, the oxygen nonstoichiometry and the oxygen permeation flux increased considerably with the increase of Cu-doping content (x = 0.1–0.3). The sintering property of the membrane decreased significantly when the Cu substitution amount reached 40%. SrFe0.7Cu0.3O3−δ showed high oxygen permeation flux, but SrCuO2 and Sr2Fe2O5 phases formed in the compound after oxygen permeation test induced cracks in the membrane.     

Mixed-conducting perovskite-type Sr_xBi_(1-X)FeO_(3-δ)oxygen-permeating membranes

SrxBi1-xFeO3- (SBF) series mixed conductors were synthesized using Standard ceramic method. The properties of such materials were characterized by XRD, O2-TPD techniques. Ab-normal crystal phenomena were found and explained and correlated with the oxygen permeation results. By analysis of the critical radius (rc), the degree of openness of the lattice (Fv) and the average metal-oxygen bonding energy of the perovskite lattice (ABE), it was proposed that the oxygen permeation flux is determined mainly by the oxygen diffusion rate in bulk when 1-x≤0.5, and by the concentration of oxygen vacancy when 1-x≥ 0.5. The stability of Sr0.5Bi0.5FeO3- was also investigated, and the high stability of it was attributed to the stable BO6 octahedra.     

Oxygen permeability and CO2-tolerance of Ce0.8Gd0.2O2-δ-Ln BaCo2O5+δ dual-phase membranes

A series of oxygen permeable dual-phase composite oxides 60 wt% Ce0.8Gd0.2O2-δ-40 wt% Ln Ba Co2O5+δ(CGO-LBCO, Ln = La, Pr, Nd,Sm, Gd and Y) were synthesized through a sol-gel route and effects of the Ln3+cations on their phase structure, oxygen permeability and chemical stability against CO2 were investigated systemically by XRD, SEM, TG-DSC and oxygen permeation experiments. XRD patterns reveal that the larger Ln3+cations(La3+, Pr3+and Nd3+) successfully stabilized the double-layered perovskite structure of sintered LBCO,while the smaller ones(Sm3+, Gd3+, and Y3+) resulted in the partial decomposition of LBCO with some impurities formed. CGO-PBCO yields the highest oxygen permeation flux, reaching 2.8×10-7mol s-1 cm-2at 925?C with 1 mm thickness under air/He gradient. The TG-DSC profiles in 20 mol% CO2/N2 and oxygen permeability experiments with CO2 as sweep gas show that CGO-YBCO demonstrates the best chemical stability against CO2, possibly due to its minimum basicity. The stable oxygen permeation flux of CGO-YBCO under CO2 atmosphere reveals its potential application in the oxy-fuel combustion route for CO2 capture.     

Synthesis and characterization of gallium-based perovskitetype dense membrane with oxygen semipermeability

La0.15Sr0.85Ga0.3Fe0.7O3-δ(LSGFO) and La0.15Sr0.85Co0.3Fe0.7O3-δ(LSCFO) mixed oxygen-ion and electron conducting oxides were synthesized by using a combined EDTA and citrate complexing method, and the corresponding dense membranes were fabricated. The properties of the oxide powders and membranes were characterized with combined SEM, XRD, H2-TPR, O2-TPD techniques, mechanical strength and oxygen permeation measurement. The results showed that LSGFO had much higher thermochemical stability than LSCFO due to the higher valence stability of Ga3+. After the temperature-programmed reduction by 5% H2 in Ar from 20℃to 1020℃, the basic perovskite structure of LSGFO was successfully preserved. LSGFO also favors the oxygen vacancy formation better than LSCFO. Oxygen permeation measurement demonstrated that LSGFO had higher oxygen permeation flux than LSCFO, but they had similar activation energy for oxygen transportation, with a value of 110 and 117 kJ ?mol~(-1), respectively. The difference in oxygen permeation f     

Syngas production in a novel perovskite membrane reactor with co-feed of CO2

Partial oxidation of methane（POM） co-fed with CO₂ to syngas in a novel catalytic BaCo_0.6Fe_0.2Ta_0.2O_3-δ oxygen permeable membrane reactor was successfully reported.Adding CO₂ to the partial oxidation of methane reaction not only alters the ratio of CO/H₂,but also increases the oxygen permeation flux and CH₄ conversion.Around 96%CH₄ conversion with more than 93%CO₂ conversion and 100%CO selectivity is achieved,which shows an excellent reaction performance.A steady oxygen permeation flux of 15 mL/（cm² min） is obtained during the 100-h operation,which shows good stability as well.     

Partial oxidation of simulated hot coke oven gas to syngas over Ru-Ni/Mg（Al）O catalyst in a ceramic membrane reactor

Hydrogen amplification from simulated hot coke oven gas (HCOG) was investigated in a BaCo0.7Fe0.2Nb0.1O3−δ (BCFNO) membrane reactor combined with a Ru-Ni/Mg(Al)O catalyst by the partial oxidation of hydrocarbon compounds under atmospheric pressure. Under optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 13.3 ml/(cm2·min). By reforming of the toluene and methane, the amount of H2 in the reaction effluent gas was about 2 times more than that of original H2 in simulated HCOG. The Ru-Ni/Mg(Al)O catalyst used in the membrane reactor possessed good catalytic activity and resistance to coking. After the activity test, a small amount of whisker carbon was observed on the used catalyst, and most of them could be removed in the hydrogen-rich atmosphere, implying that the carbon deposition formed on the catalyst might be a reversible process.     

Grafting Branch Length and Density Dependent Performance of Zwitterionic Polymer Decorated Polypropylene Membrane

Branch length and density have critical effects on membrane performances;however,it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods.In this study,zwitterionic polymer with controlled grafting branch chain length (degree of polymerization) and grafting density (grafting chains per membrane area) was tethered to the microporous polypropylene membrane surface based on the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization technique with click reaction.The modified membranes were tested by filtrating protein dispersion to highlight the correlations of branch chain length and grafting density with the membrane permeation performances.The pure water flux,the flux recovery ratio are positively and significantly,and the irreversible fouling negatively and significantly correlated with grafting density.These results demonstrate that the larger the coverage of the membrane with poly{[2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl) ammonium hydroxide} (PMEDSAH),the higher the pure water flux and the higher the flux recover ratio,and the lower the irreversible fouling,which shows that high grafting density is favorable to fouling reducing.     

Effect of dopant valence on the oxygen desorption and oxygen permeability of SrCo0.4Fe0.5M0.1O3-δ （M -Ni,Al and Zr） mixed-conducting oxides

The effect of dopant valence on oxygen desorption and oxygen permeability of SrCo0.4Fe0.5M0.1O3-δ （M = Ni, Al and Zr） mixed-conducting oxides were investigated in detail by O2-TPD and oxygen permeation measurement. The SrCo0.4Fe0.5M0.1O3-δ for M = Fe, Ni, Al and Zr were denoted as SCF, SCFN, SCFA and SCFZ, respectively. O2-TPD analysis revealed that the amount of α oxygen desorption decreased with increasing the valance of doped metal elements （SCFN 〉 SCFA SCF 〉 SCFZ）. The oxygen permeation flux at the temperature ≈igher than 1148 K decreased in the order of SCFN 〉 SCF 〉 SCFZ 〉 SCFA. Single activation for oxygen permeation was observed for SCFZ oxide and the activation energies of SCF and SCFA change at around 1073 K, while the change temoerature of SCFN was about 1173 K.     

Oxygen permeability and CO_2-tolerance of Ce_(0.8)Gd_(0.2)O_(2-δ)-Ln BaCo_2O_(5+δ) dual-phase membranes

A series of oxygen permeable dual-phase composite oxides 60 wt% Ce0.8Gd0.2O2-δ-40 wt% Ln Ba Co2O5+δ(CGO-LBCO, Ln = La, Pr, Nd,Sm, Gd and Y) were synthesized through a sol-gel route and effects of the Ln3+cations on their phase structure, oxygen permeability and chemical stability against CO2 were investigated systemically by XRD, SEM, TG-DSC and oxygen permeation experiments. XRD patterns reveal that the larger Ln3+cations(La3+, Pr3+and Nd3+) successfully stabilized the double-layered perovskite structure of sintered LBCO,while the smaller ones(Sm3+, Gd3+, and Y3+) resulted in the partial decomposition of LBCO with some impurities formed. CGO-PBCO yields the highest oxygen permeation flux, reaching 2.8×10-7mol s-1 cm-2at 925?C with 1 mm thickness under air/He gradient. The TG-DSC profiles in 20 mol% CO2/N2 and oxygen permeability experiments with CO2 as sweep gas show that CGO-YBCO demonstrates the best chemical stability against CO2, possibly due to its minimum basicity. The stable oxygen permeation flux of CGO-YBCO under CO2 atmosphere reveals its potential application in the oxy-fuel combustion route for CO2 capture.     

Thermocontrolling ion permeation through binary component membrane composed of crown ether liquid crystal/PVC

In view of the nature of orderness in structure and the mesomorphism in property of liquid crystal, the function of which is further exploited by integrating it with the feature of crown ether. The monoarmed crown ether liquid crystals are successfully applied to the imitation of biomembrane transport. Binary component membrane composed of crown ether liquid crystal and PVC was first developed. Such a novel model of biomimetic membrane is capable of imitating ingeniously the thermocontrolling transport of biomembrane, thus the essential function of liquid crystal in membane transport is more fully exploited. It was suggested, consequently, that the molecules of the crown ether liquid crystal could assemble themselves to form ionic channels, as they exist in mesophase.Of still more significance is that the thermocontrolling transport of ions through the membrane is found to be operative selectively and the permeation of ion is under the direct influence of the thermal turmoil of the crown ether liquid cr     

Application of heat-activated peroxydisulfate process for the chemical cleaning of fouled ultrafiltration membranes

Na Cl O has been widely used to restore membrane flux in practical membrane cleaning processes, which would induce the formation of toxic halogenated byproducts. In this study, we proposed a novel heatactivated peroxydisulfate(heat/PDS) process to clean the membrane fouling derived from humic acid(HA). The results show that the combination of heat and PDS can achieve almost 100% recovery of permeate flux after soaking the HA-fouled membrane in 1 mmol/L PDS solution at 50 °C for 2 h, which is att...     

BaxCe0.8Y0.2O3-α固体电解质的氧离子导电性

Ba_xCe_0.8Y_0.2O_3-α(x=1.03，1，0.98) solid electrolyte samples show a single phase of orthorhombic perovskite of BaCeO₃. The oxide-ion conduction and transport number were detected in the temperature of 600～1000℃ by electrochemical oxygen permeation (oxygen pumping)， and compared with the results from the oxygen concentration cell. The relation between the ingredient of Ba and oxide-ion conduction was also researched. It was found that these electrolytes exhibited the mixed oxide-ionic and electronic hole conduction under the experimental temperature and oxygen gas. The oxide-ion transport numbers are 0.1～0.6， which are close to the results of the oxygen con-centration cell. They increase as the decrease of Ba content in the samples.     

Effects of Aluminum on Thermal Decomposition of Hexogen/Ammonium Perchlorate

Thermogravimetry-differential scanning calorimetry-mass spectrometry-Fourier transform infrared spectrometry（TG-DSC-MS-FTIR） simultaneous analysis was used to study the effects of 10.7 μm and 40 nm Al on the thermal decomposition of the Hexogen/ammonium perchlorate（RDX/AP,1/2,mass ratio） mixture.TG-DSC results show that there are two mass loss processes for the thermal decomposition of RDX/AP/Al.The first one is mainly ascribed to the thermal decomposition of RDX.The reaction rate of RDX/AP/10.7 μm Al is so fast that the apparent activation energy,calculated by model-free Friedman method,is negative,which is the same as that of RDX/AP.30％（mass fraction） 40 nm Al added in RDX/AP change the activation energy from negative to positive value.The second mass loss process of the RDX/AP/A1 mixture is ascribed to the thermal decomposition of AP.This process can be divided into three stages for RDX/AP with and without Al.The kinetics model is not changed in the presence of micro-sized Al,while it is changed from CnB/D1/D1 to CnB/D1/D4 after the addition of 40 nm Al to RDX/AP.The reaction rate constant of the first stage and the end temperature of the second stage decrease,while the end temperatures of the third stage increase in the presence of 40 nm Al.The MS-FTIR results show there is a competition between the formation reactions of HNCO,N2O and NO2 during the second mass loss process.     

A Self-supporting,Surface Carbonized Filter Paper Membrane for Efficient Water-in-Oil Emulsion Separation

Due to the important role of oil source in our life, the separation of water-in-oil emulsion is urgent and necessary. Membrane seperation technology has been an efficient and widely used method in separating oil-water separation. Herein, we report a versatile approach to fabricate surface carbonized membranes with self-standing property from biomass-derived precursor by synergistic charring of phytic acid,arginine and filter paper. The obtained membrane exhibited superhydrophobicity in oil, excellent fouling resistance, and self-supporting ability.The membrane can be cycle-used at least 12 times with high permeation flux(up to 1380 L·m~(-2)·h~(-1)) and separation efficiency(up to 99.4%).     

Thermo-chemical reactions and structural evolution of acrylamide-modified polyacrylonitrile

<正>Thermal properties of acrylonitrile(AN)-acrylamide(AM) copolymers for carbon fibers were studied by DSC and in situ FTIR techniques in nitrogen(N_2) and air flows.The cyclization mechanism and stabilization behavior of polyacrylonitrile(PAN) were discussed.In N_2 flow,it was found that AM had the ability to initiate and accelerate cyclization process,which was confirmed by the fact that the initiation of nitriles shifted to a lower temperature.Compared to AN homopolymer,the initiation temperature of cyclization was ahead 32 K by introducing 3.59 mol%AM into the copolymer.The exothermic reaction was relaxed due to the presence of two separated exothermic peaks.Accompanied by DSC,in situ FTIR and calculation of activation energy,the two peaks were proved to be caused by ionic cyclization and free radical cyclization,respectively,and the corresponding cyclization mechanism was proposed.With increasing in AM content,the ionic cyclization tends to be dominant and the total heat liberated first increases and then decreases.For AN homopolymer,the activation energy of cyclization is 179 kJ/mol.For AN-AM copolymer(containing 3.59 mol%AM),the activation energy of ionic cyclization is 96 kJ/mol and that of free radical cyclization is 338 kJ/mol.In air flow,similar cyclization routes occur and the difference is the contribution of oxidation.The oxygen in environment has no remarkable effect on cyclization of AN homopolymer but retards the cyclization of AN-AM copolymers.For AN-AM copolymer with 3.59 mol%AM,the cyclization temperature is postponed 10℃in air.     

Mineralization of 4-Chlorophenol under Visible Light Irradiation in the Presence of Aluminum and Zinc Phthalocyaninesulfonates

Photosensitized oxidation of 4-chlorophenol (4CP) by the title complexes (AIPcS and ZnPcS) in aerated aqueous solution uponvisible light irradiation(λ=450nm) has been investigated using methanol as a disassociating reagent.It is confirmed that the monomeric species of the sesitizer is more active than the corresponding dimer in singlet oxygen generation for 4CP oxidation.However,the monomer is also the main component found in the sensitlzer‘s photobleaching, In this reload, AIPcS is much more stable than ZnPcS, and the Dhotoble~hlno is observed to proceed via singlet and triplet oxygen, respectlvely.The final products of 4CP oxidation in alkaline solution are carbon dioxide and chloride ions.while at pH=7 and pH=3 the p-benzoquinone is the product.The temperature is found to have influence on both the photosensitized degradation of methyl orange and ZnPcS photobleaching,with an activation energy of 15.8 and 24.2kJ/mol,respectively.     

Study on the recovery of ionic liquids from dilute effluent by electrodialysis method and the fouling of cation-exchange membrane

With the wide application of ionic liquids(ILs)in various fields,developing efficient techniques to recover ILs from effluent is an urgent demand for the cost reduction and the environmental protection.In this study,an electrodialysis(ED)method was used to recover 1-butyl-3-methylimidazolium chloride([Bmim]Cl)IL from aqueous solution as model effluent.The influences of initial IL concentration and applied voltage on the current efficiency,removal ratio,desalination ratio,membrane flux and specific energy consumption during the ED process were investigated.It was found that the removal ratio and desalination ratio increases with the increasing of initial IL concentration and applied voltage.The current efficiency decreases with the increasing of initial IL concentration and the current efficiency reached the maximum value of 94.3%at 25 V.Besides,as the applied voltage increases,the membrane flux increases and the specific energy consumption decreases.Moreover,the fouling of cation-exchange membrane was also discovered after the desalination of IL.The deposits on the surface or into the membrane which is probably caused by[Bmim]+was characterized by scanning electron microscopy,elemental analysis and Fourier transform infrared.     

Preparation of a novel composite electrode based on N-doped TiO_2-coated Na Y zeolite membrane and its photoelectrocatalytic performance

For the first time the preparation of the N-doped TiO_2-coated NaY zeolite membrane(N-doped TiO_2/NaY zeolite membrane) as an electrode material for photoelectrocatalysis has been achieved and reported.The XRD, SEM, UV–vis and XPS techniques were used to characterize the structure of the N-doped TiO_2/NaY zeolite membrane. The results verified that the surface of the N-doped TiO_2/NaY zeolite membrane was coated by TiO_2 nanoparticles of ca. 20 nm size and exhibited a distinct red-shift in the UV–vis spectra compared to N-doped TiO_2. The photoelectrocatalysis performance of the N-doped TiO_2/NaY zeolite membrane electrode was evaluated by phenol degradation. The results revealed it is a promising novel electrode material for application of photoelectrocatalysis in the removal of organic contaminants in waste water.     

Preliminary Study on Hydrogen Permeation and Stability of BaCe0.90Y0.10O3-δ Membrane under Asymmetric Atm osphere

High-temperature proton conductors (HTPC) have been extensively studied since I wahara et al?1? reported protonic conduction in SrCeO3-based oxid es. Later, the BaCeO3-based oxides, such as BaCe0.90Yb0.10O3- d (BCYb10) and BaCe0.90Y0.10-O3-d (BCY10), we re fou nd to show higher conductivity?2?. High electronic and protonic conducti vity makes BCY10 a potential membrane for hydrogen separation?3?. Thin f ilms with high density, most probably made by sequential coating on porous subst rates, are imperative in order to promote hydrogen permeation flux?4?. T his makes it more necessary for such membranes to be kept stable and unspoilt un der asymmetric hydrogen-permeation atmosphere at elevated temperatures. In this paper, the stability and hydrogen permeation ability of BCY10 membrane are stud ied by XRD, SEM, energy dispersive X-ray (EDX) analysis, H2-TPR process and hydrogen permeation experiment. The results showed that hydrogen cannot permeate through the BCY10 membrane without surface modification, and its surface cannot keep a uniform perovskite structure in the asymmetric atmosphere.