Optimization of a continuous ultrasound assisted oxidative desulfurization (UAOD) process of diesel using response surface methodology (RSM) considering operating cost

A continuous-flow ultrasound-assisted oxidative desulfurization(UAOD) of partially hydro-treated diesel has been investigated using hydrogen peroxide-formic acid as simple and easy to apply oxidation system. The effects of different operating parameters of oxidation stage including residence time(2–24 min), formic acid to sulfur molar ratio(10–150), and oxidant to sulfur molar ratio(5–35) on the sulfur removal have been studied using response surface methodology(RSM) based on Box–Behnken design. Considering the operating costs of the continuous-flow oxidation stage including chemical and electrical energy consumption, the appropriate values of operating parameters were selected as follows: residence time of 16 min, the formic acid to sulfur molar ratio of 54.47, and the oxidant to sulfur molar ratio of 8.24. In these conditions, the sulfur removal and the volume ratio of the hydrocarbon phase to the aqueous phase were 86.90% and 4.34, respectively. By drastic reduction in the chemical consumption in the oxidation stage, the volume ratio of the hydrocarbon phase to the aqueous phase was increased up to 10. Therefore, the formic acid to sulfur molar ratio and the oxidant to sulfur molar ratio were obtained 23.64 and 3.58, respectively, which lead to sulfur removal of 84.38% with considerable improvements on the operating cost of oxidation stage in comparison with the previous works.     

用过氧化氢和乙酸对未经氢化处理的煤油进行直接氧化脱硫

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 (nacid/nS), and oxidant to sulfur molar ratio (nO/nS) 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 nO/nS related to the reaction temperature and the best sulfur removal could be obtained at nO/nS 8 and 23 for the reaction temperatures of 25 and 60C, respectively. The maximum observed sulfur removal in the present oxidative desulfurization system was 83.3%.     

Effect of potassium permanganate dosing position on the performance of coagulation/ultrafiltration combined process

The effects of potassium permanganate(KMnO_4)dosing position on the natural organic matter(NOM)removal as well as membrane fouling were investigated in the coagulation/ultrafiltration combined process.KMnO_4 oxidation altered the NOM characteristics in terms of hydrophobicity and molecular weight,and destroyed humic substances originated from terraneous organisms in raw water.The optimal KMnO_4 dosage was 0.5 mg·L~(-1) in the peroxidation enhanced coagulation process with respect to the dissolved organic carbon(DOC)removal.When KMnO_4 was dosed into both upstream and downstream of coagulation,namely in the proposed twoposition dosing mode,coagulation and KMnO_4 oxidation worked individually on the apparent DOC removal.However,compared to the KMnO_4 addition prior to or after coagulation,the two-position dosing mode dramatically alleviated membrane fouling and reduced fouling irreversibility.This was attributed to the change of NOM characteristics as a result of KMnO_4 addition prior to coagulation and the presence of MnO_2 on membrane surface as a result of KMnO_4 addition prior to ultrafiltration.This work may provide useful information for the application of KMnO_4 oxidation in the coagulation/ultrafiltration combined system.     

用UV/H2O2,UV/O3,UV/H2O2/O3催化处理城市固体垃圾填埋渗出物

The performance of UV/H2O2, UV/O3, and UV/H2O2/O3 oxidation systems for the treatment of municipal solid-waste landfill leachate was investigated. Main objective of the experiment was to remove total organic carbon (TOC), non-biodegradable organic compounds (NBDOC) and color. In UV/H2O2 oxidation experiment, with the increase of H2O2 dosage, removal efficiencies of TOC and color along with the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) of the effluent were increased and a better performance was obtained than the system H2O2 alone. In UV/H2O2 oxidation, under the optimum condition H2O2 (0.2 time), removal efficiencies of TOC and color were 78.9% and 95.5%, respectively, and BOD/COD ratio was significantly increased from 0.112 to 0.366. In UV/O3 oxidation, with the increase of O3 dosage, removal efficiencies of TOC and color along with BOD/COD ratio of the effluent were increased and a better performance was obtained than the system O3 alone. Under the optimum condition UV/O3     

三相体系中TS-1分子筛催化环己酮氨肟化制环己酮肟(英文)

An innovative green process of producing ε-caprolactam was proposed by integrating ammoximation and Beckmann rearrangement effectively. As a first part of the new process, TS-1 molecular sieve-catalyzed synthesis of cyclohexanone oxime from cyclohexanone, ammonia and hydrogen peroxide was carried out in a batch plant. Cyclohexane was used as the solvent in the three-phase reaction system. The influences of essential process parameters on ammoximation were investigated. Under the reaction conditions as catalyst content of 2.5% (by mass); H 2 O 2 /yclohexanone molar ratio of 1.10; NH 3 /cyclohexanone molar ratio of 2.20; reaction temperature of 343 K; reaction time of 5 h, high conversion of cyclohexanone and selectivity to oxime (both>99%) were obtained. Thus, the three-phase ammoximation process showed equal catalytic activity as TS-1 but much more convenient and simpler for the separation of catalyst in comparison to the industrial two-phase system with t-butanol used as solvent.     

椰油丙基酰胺甜菜碱/聚乙二醇水溶液的分相研究

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 con-centration 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, Ccp (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 Ccp, independent of PEG molecular weight.     

负载金属氧化物分子筛催化氧化模拟汽油的脱硫研究

A simulated gasoline consisting of model sulfur compounds of thiophene （C4H4S） and 3-methythiophene （3-MC4H4S） dissolved in n-heptane was tested for the oxidative desulfurization in the hydrogen peroxide （H202） and formic acid oxidative system over metal oxide-loaded molecular sieve. The effects of the oxidative system, loaded metal oxides, phase transfer catalyst, the addition of olefin and aromatics on sulfur removal were investigated in details. The results showed that the sulfur removal rate of simulated gasoline in the H202/formic acid system was higher than in other oxidative systems. The cerium oxide-loaded molecular sieve was found very active catalyst for oxidation of simulated gasoline in this system. The sulfur removal rates of C4H4S and 3-MC4H4S were enhanced when phase transfer catalyst （PTC） was added. However, the sulfur removal rate of simulated gasoline was reduced with the addition of olefin and aromatics.     

Analysis of H2S Tolerance of Pd-Cu Alloy Hydrogen Separation Membranes

The presence of a limited amount of H2S in H2-rich feed adversely affects the Pd-Cu membrane per-meation performance due to the sulphidization of the membrane surface. A theoretical model was proposed to pre-dict the S-tolerant performance of the Pd-Cu membranes in presence of H2S under the industrial water-gas-shift （WGS） reaction conditions. The ideas of surface coverage and competitive adsorption thermodynamics of H2S and H2 on Pd-Cu surface were introduced in the model. The surface sulphidization of the Pd-Cu membranes mainly de-pended on the pressure ratio of H2S to H2, temperature and S-adsorbed surface coverage, i.e., the occurrence of sulphidization on the surface was not directly related with the bulk compositions and structures [body centered cu-bic and face centered cubic （bcc or fcc）] of Pd-Cu alloy membranes because of the surface segregation phenomena. The resulting equilibrium equations for the H2S adsorption/sulphidization reactions were solved to calculate the pressure ratio of H2S to H2 over a wide range of temperatures. A validation of the model was performed through a comparison between lots of literature data and the model calculations over a rather broad range of operating condi-tions. An extremely good agreement was obtained in the different cases, and thus, the model can serve to guide the development of S-resistant Pd alloy membrane materials for hydrogen separation.     

Regulation of isobutane/1-butene adsorption behaviors on the acidic ionic liquids-functionalized MCM-22 zeolite

The adsorption ratio of isobutane/1-butene on the catalyst surface is one of the most important factors for the C4 alkylation process.Regulation of isobutane/1-butene adsorption ratio on the zeolite-supported acid catalyst is a big challenge for catalyst preparation.To regulate the isobutane/1-butene adsorption ratio,four types of ionic liquid (i.e.,IL) with different alkyl chain lengths and different acid group numbers were synthesized and were subsequently immobilized onto the MCM-22 zeolite.The as-synthesized IL-immobilized MCM-22 (i.e.,MCM-22-IL) was characterized by FTIR,TGA,BET,XPS and XRD,and their adsorption capacities and adsorption molar ratios of isobutane to 1-butene (I/O) were investigated to correlate with surface features of MCM-22-IL Results showed that the immobilization of ILs led to a decrease of specific surface area and pore volume.But the surface density of acid groups was increased and the adsorption molar ratio of isobutane/1-butene (I/O) was significantly improved by the immobilization of ionic liquids.The adsorption molar ratio of I/O is substantially improved from 0.75 to above 0.9 at 300 kPa upon immobilizing ILs.Although the alkyl chain length of ILs was found to have little effect on the adsorption molar ratio of I/O,the increase of acid group numbers led to a dramatic decrease in the adsorption I/O ratio.The results illustrated that immobilizing ionic liquids is an effective way to modify the textural,chemical and morphological properties of MCM-22.Accordingly,the immobilization of ionic liquids provides a novel and a feasible way to regulate the adsorption I/O ratio on an adsorbent or a solid catalyst.     

Experimental Study on Hydrogenation of SiCl_4 to SiHCl_3 in a Stirred Bed Reactor

The hydrogenation of SiCl_4 to SiHCl_3 was studied in a stirred bed reactor with CuCl catalyst.The properties of the CuCl catalysts and silicon particles before and after the reaction were characterized by SEM,XRD and XPS.The XRD showed that the active component of Cu3Si was formed during the reaction,and the EDX proved the molar ratio of Cu and Si on the region of apertures.The valent of Cu was discussed by XPS before and after the hydrogen reaction.Then the effects of the reaction temperature,pressure,molar ratio of H2 to SiC l4,weight hourly space velocity(WHSV),and catalyst loading were studied.The results showed that the conversion rate of Si Cl4 was about 38%at WHSV of 190 Nm3/(t·h),temperature of 540℃,pressure of 1.8 MPa,catalyst loading of 0.9%(ω),and molar ratio of H2 to Si Cl4 1.7:1.Based on the experemental results,a reaction mechanism was proposed,which involved the continuous consumption of silicon(many apertures was showed on SEM image)and formation of new Cu3Si active component during the hydrogenation reaction.     

ADVANCED CHEMICAL OXIDATION OF 2,4,6 TRICHLOROPHENOL IN AQUEOUS PHASE BY FENTON'S REAGENT-PART I: EFFECTS OF THE AMOUNTS OF OXIDANT AND CATALYST ON THE TREATMENT REACTION

Fenton's Reagent is a strong oxidant for 2,4,6 Trichlorophenol (TCP) in aqueous phase. This reaction can be effectively utilized to treat an industrial wastewater containing TCP, and reduce the toxicity of the discharge. This paper reports the effects of the amounts of the oxidant (hydrogen peroxide) and the catalyst (ferrous ions), relative to TCP, on the rates and extents of reaction. The progress of each reaction has been monitored in terms of TCP removal, chloride ions release from the organic structure, change in pH, and the reductions in COD and TOC. This information is important in order to maximize the level of treatment with minimum application of chemicals. A set of optimum molar ratios of oxidant to substrate, and catalyst to oxidant were determined.     

HDPE/LLDPE reactor blends with bimodal microstructures—Part II: rheological properties

Reactor blends of polyethylene/poly(ethylene-co-1-octene) resins with bimodal molecular weight and bimodal short chain branching distributions were synthesized in a two-step polymerization process. The compositions of these blends range from low molecular weight (LMW) homopolymer to high molecular weight (HMW) copolymer and vice versa HMW homopolymer to LMW copolymer. The shear flow characteristics of these polymers in the typical processing range mostly depend on the molecular weight and MWD of the polymer and are independent of the short chain branch content. From oscillatory shear measurements, it was observed that the viscosity of HMW polymers was reduced with the addition of LMW material. For the polymers produced with this two-step polymerization process, the LMW homopolymer and HMW copolymer blends and HMW homopolymer and LMW copolymer blends were melt miscible, despite the large viscosity differences of the pure components.     

Rheological behavior and mechanical properties of high‐density polyethylene blends with different molecular weights

The dynamic rheological and mechanical properties of the binary blends of two conventional high‐density polyethylenes [HDPEs; low molecular weight (LMW) and high molecular weight (HMW)] with distinct different weight‐average molecular weights were studied. The rheological results show that the rheological behavior of the blends departed from classical linear viscoelastic theory because of the polydispersity of the HDPEs that we used. Plots of the logarithm of the zero shear viscosity fitted by the Cross model versus the blend composition, Cole–Cole plots, Han curves, and master curves of the storage and loss moduli indicated the LMW/HMW blends of different compositions were miscible in the melt state. The tensile yield strength of the blends generally followed the linear additivity rule, whereas the elongation at break and impact strength were lower than those predicted by linear additivity; this suggested the incompatibility of the blends in solid state. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Removal Characteristics of Organic Pollutants in Sewage Treatment by a Pre-Coagulation,Ozonation and Ozone/Hydrogen Peroxide Process

The applicability of a sequential process of ozonation and ozone/hydrogen peroxide process for the removal of soluble organic compounds from a pre-coagulated municipal sewage was examined. 6–25% of initial T-COD_Cr was removed at the early stage of ozonation before the ratio of consumed ozone to removed T-COD_Cr dramatically increased. Until dissolved ozone was detected, 0.3 mgO₃/mgTOC₀ (Initial TOC) of ozone was consumed. When an ozone/hydrogen peroxide process was applied, additional COD_Cr was removed. And we elucidated that two following findings are important for the better performance of ozone/hydrogen peroxide process; those are to remove readily reactive organic compounds with ozone before the application of ozone/hydrogen peroxide process and to avoid the excess addition of hydrogen peroxide. Based on these two findings, we proposed a sequential process of ozonation and multi-stage ozone/hydrogen peroxide process and the appropriate addition of hydrogen peroxide. T-COD_Cr, TOC and ATU-BOD₅ were reduced to less than 7 mg/L, 6 mgC/L and 5 mg/L, respectively after total treatment time of 79 min. Furthermore, we discussed the transformation of organic compounds and the removal of organic compounds. The removal amount of COD_Cr and UV₂₅₄ had good linear relationship until the removal amounts of COD_Cr and UV₂₅₄ were 30 mg/L and 0.11 cm^?1, respectively. Therefore UV₂₅₄ would be useful for an indicator for COD_Cr removal at the beginning of the treatment. The accumulation of carboxylic acids (formic acid, acetic acid and oxalic acid) was observed. The ratio of carbon concentration of carboxylic acids to TOC remaining was getting higher and reached around 0.5 finally. Removal of TOC was observed with the accumulation of carboxylic acids. When unknown organic compounds (organic compounds except for carboxylic acids) were oxidized, 70% was apparently removed as carbon dioxide and 30% was accumulated as carboxylic acids. A portion of biodegradable organic compounds to whole organic compounds was enhanced as shown by the increase ratio of BOD/COD_Cr.     

Ozone,Oxalic Acid,and Organic Matter Molecular Weight – Effects on Coagulation

Ozonation breaks long chain natural organic matter (NOM) into smaller, more oxygenated compounds such as oxalic acid. The purpose of this study was to evaluate the effects of such transformations on coagulation in high dissolved organic carbon synthetic waters with model particles. Results indicate that the presence of oxalic acid adversely affects the removal of turbidity and organic carbon by coagulation and filtration. The results also show that larger (higher molecular weight) organic matter is easier to remove by coagulation than lower molecular weight organic matter. In both cases, ozonation results in an increase in the optimum coagulant dose or a decrease in the amount of turbidity and TOC removal at a given coagulant dose.     

乙醛酸合成的研究

用乙二醛作原料,过氧化氢为氧化剂,硫酸亚铁作催化剂合成乙醛酸,通过正交实验确定了最佳的合成工艺条件是:原料摩尔比n(乙二醛)∶n(过氧化氢)∶n(硫酸亚铁)=1∶1.1∶0.05,在温度3～5°C条件下,用2h将过氧化氢和硫酸亚铁溶液滴加到乙二醛的溶液中,继续反应3h,用离子交换树脂分离提纯,再用减压蒸馏浓缩,可制得约30%(质量分数)含量的乙醛酸。     

Advanced oxidation of cork‐processing wastewater using Fenton's reagent: kinetics and stoichiometry

This work evaluates Fenton oxidation for the removal of organic matter (COD) from cork‐processing wastewater. The experimental variables studied were the dosages of iron salts and hydrogen peroxide. The COD removal ranged from 17% to 79%, depending on the reagent dose, and the stoichiometric reaction coefficient varied from 0.08 to 0.43 g COD (g H₂O₂)^?1 (which implies an efficiency in the use of hydrogen peroxide varying from 17% to 92%). In a study of the process kinetics, based on the initial rates method, the COD elimination rate was maximum when the molar ratio [H₂O₂]_o:[Fe²⁺]_o was equal to 10. Under these experimental conditions, the initial oxidation rate was 50.5 mg COD dm^?3 s^?1 with a rate of consumption of hydrogen peroxide of 140 mg H₂O₂ dm^?3 s^?1, implying an efficiency in the use of the hydrogen peroxide at the initial time of 77%. The total amount of organic matter removed by Fenton oxidation was increased by spreading the H₂O₂ and ferrous salt reagent over several fractions by 15% for two‐fractions and by 21% for three‐fractions. Copyright © 2004 Society of Chemical Industry     

Batch and Fed‐Batch Degradation of Enrofloxacin by the Fenton Process

Enrofloxacin is a synthetic second‐generation fluoroquinolone used as an antimicrobial agent exclusively in veterinary medicine. To simulate the treatment of wastewater contaminated by enrofloxacin, four‐day long fed‐batch runs were carried out according to the Fenton process with an enrofloxacin solution as model, to which hydrogen peroxide and ferrous ion were added twice a day. The residual enrofloxacin concentration was practically coincident to that detected at the end of the batch tests. Hydrogen peroxide was almost completely consumed after each feeding period, while the total organic carbon (TOC) concentration decreased gradually within three days, corresponding to a reduction > 58 %. From the third day on, the TOC falling rate was quite low. A yellow sludge settled due to the precipitation of both Fe(OH)₃ and a complex formed by ferric ion with adsorbed enrofloxacin and/or its oxidation products.     

Crystallized polyarylene ether nitrile blends with improved thermal,mechanical, dielectric properties,and processability

In this work, the biphenol polyarylether nitrile (BP‐PEN) films with improved processability were prepared by blending low molecular weight (LMW) with high molecular weight (HMW) of BP‐PEN. The hybrid membrane exhibited excellent thermal stability and mechanical strength. The T_id values of the films were as high as 505°C–522°C. Melting behavior studies indicated that the crystallinity of LMW BP‐PEN was higher than that of HMW, which was confirmed by the X‐ray diffraction (XRD) patterns analysis as well. Scanning electron microscope (SEM) provided additional information on morphology and phase adhesion. Additionally, the polymer crystallinity dependent on dielectric properties of blends films is reported. Most importantly, it is found that the combination of LMW and HMW BP‐PEN would be an effective method to simultaneously increase the mechanical, thermal, dielectric properties, and polymer processability. POLYM. COMPOS., 38:126–131, 2017. © 2015 Society of Plastics Engineers     

Catalytic removal of phenol from aqueous solutions in a trickle‐bed reactor

The degradation of high concentrations of phenol (1g/dm^?3) in aqueous media at high temperatures (100–190 °C) and pressures (2.0 MPa) has been studied by catalytic wet air oxidation in a trickle‐bed reactor. The effect of reaction temperature, weight hourly space velocity (WHSV) and hydrogen peroxide concentration on phenol concentration, total organic carbon (TOC) and chemical oxygen demand (COD) conversion by using a commercial copper catalyst has been investigated. At 150 °C, TOC removal increased by 28% with the WHSV of 62.5 h^?1. The addition of hydrogen peroxide as a free radical promoter significantly enhanced the depletion rate of phenol. A kinetic study has been carried out leading to the determination of the kinetic constants for the removal of TOC. Copyright © 2005 Society of Chemical Industry