PTA装置氧化反应系统开车过程逻辑控制优化

介绍了PTA装置的氧化反应系统工艺过程及控制原理,讨论了基于传统DCS控制系统的氧化反应系统开车过程中的存在的问题。针对上述问题,运用逻辑代数提出了将反应过程规律和设备运行规律之间的关系进行逻辑化处理的解决方案,提前预防事故和故障,避免事后制定反事故措施和消除缺陷。方案实施效果表明:PTA装置氧化反应系统采用开车过程逻辑控制方案后,节约了开车时间并减少了开车错误的发生。为避免开车错误指明方向并提供了方法。

A Smog Chamber Facility for Qualitative and Quantitative Study on Atmospheric Chemistry and Secondary Organic Aerosol

In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ～830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere.

Effects of Selenium Dioxide on Apoptosis, Bcl-2 and P53 Expression, Intracellular Reactive Oxygen Species and Calcium Level in Three Human Lung Cancer Cell Lines

Objective: To evaluate the anti-tumor effects of SeO2 and its mechanisms on three human lung cancer cell lines. Methods: Three lung cancer cells A549, GLC-82 and PG were treated with 3-30 μmol/L SeO2. Flow cytometry was used to detect apoptosis, and analyze the changes of expression of p53 and Bcl-2, as well as ROS and Ca2+ level within cells. Results:SeO2 markedly inhibited cell proliferation and viability, and prompted apoptosis after 48 h treatment. SeO2 at 10 μmol/L induced 47.8% apoptosis in A549 cells, 40.8% in GLC-82 cells, 18.2% in PG cells. SeO2 at 30 μmol/L induced 37.8% apoposis in PG cells,but did not increase apoptotic raes in other two cells. SeO2 could down-regulate the mean fluorescent intensity of Bcl-2 from 65.8 to 9.6 in A549, but not in GLC-82 and in PG cells, up-regulate wild type p53 level in all three cells. SeO2 decreased the ROS and Ca2+ level markedly within three tested cells. Conclusion: SeO2 showed anti-tumor effect via apoptosis pathway in three lung cancer cell lines. The decrease of ROS and Ca2+ level within cells as well as regulation of Bcl-2 and p53 expression may play important roles in above apoptotic procedure.

Study on the Mechanisms for Baeyer-Villiger Oxidation of Cyclohexanone with Hydrogen Peroxide in Different Systems

The green and effective Baeyer-Villiger oxidation reaction of cyclohexanone for preparing e-caprolactone is of particular importance in the synthesis of new polymer materials. We have discussed here several mechanism types of Baeyer-Villiger oxidation of cyclohexanone with H2O2 in different reaction systems. Five main types have been addressed, i. e.： （1） the non-catalyzed reaction type, where the C=O of ketones is activated by H＋, which is electrolytically dissociated from H202 and H20, to improve the capability of C=O group for accepting the electron pairs; （2） the thermally activated radical reaction type, where the Criegee intermediate is produced via two steps of radical reaction with -OH attack, with much more hydroxyl radicals being excited in the presence of TS-1 zeolite; （3） the Bronsted acid catalysis reaction type, where both O-O moiety and C=O group could be activated by BriSnsted acid; （4） the solid Lewis acid catalyzed C=O of the substrate activation reaction type through enhancing the donor-acceptor interaction between the antibonding π＊c-o orbital of cyclohexanone and HOMO of Sn-containing zeolites; and （5） the solid Lewis acid catalyzed H202 to form Me-OOH oxidative species by converting the highest occupied molecular orbital （HOMO） of Ti-OOH into a singly occupied molecular orbital （SOMO）, making the O--O group highly electrophilic to attack the C--O of cyclohexanone during the Baeyer-Villiger oxidation process. In the end, we have also compared the different mechanisms and put forward our opinions on the development direction of catalytic materials aiming at eco-friendly Baeyer-Villiger oxidation of cyclohexanone in the years to come.

Blocking backward reaction on hydrogen evolution cocatalyst in a photosystem Ⅱ hybrid Z-scheme water splitting system

Photocatalytic Z-scheme water splitting is considered as a promising approach to produce solar hydrogen.However,the forward hydrogen production reaction is often impeded by backward reactions.In the present study,in a photosystem Ⅱ-integrated hybrid Z-scheme water splitting system,the backward hydrogen oxidation reaction was significantly suppressed by loading a PtCrOx cocatalyst on a ZrO2/TaON photocatalyst.Due to the weak chemisorption and activation of molecular hydrogen on PtCrOx,where Pt is stabilized in the oxidized forms,Pt^Ⅱ and Pt^Ⅳ,hydrogen oxidation is inhibited.However,it is remarkably well-catalyzed by the metallic Pt cocatalyst,thereby rapidly consuming the produced hydrogen.This work describes an approach to inhibit the backward reaction in the photosystem Ⅱ-integrated hybrid Z-scheme water splitting system using Fe(CN)6^3-/Fe(CN)6^4-redox couple as an electron shuttle.

A new apparatus to establish the spontaneous combustion propensity of coals and coal-shales

Coal and coal-shale both tend to undergo spontaneous combustion under favourable atmospheric conditions. The Wits-Ehac index has been developed in South Africa since the late 1980's to test the spontaneous combustion liability of coal. However, in some cases, the Wits-Ehac index fails to produce tangible results when testing coal-shales. To overcome this problem, a new apparatus has been developed to test carbonaceous materials such as coal and coal-shale under chemical reactions with oxygen and an index has been obtained. This index is called the Wits-CT index. The equipment emulates the influence of oxygen adsorption on carbonaceous material for a period of 24 h without a heating system.The Wits-CT index uses the total carbon content of the sample and the temperature variations obtained from the samples during reaction with oxygen to predict the spontaneous combustion liability. Eighteen samples have been analyzed using both indices and the results are in-line. It was found that coals and coal-shales with higher values of the Wits-CT index are more liable to spontaneous combustion.Further research on different coal-shales is underway in order to establish an extensive database for coal and coal-shales, together with known incidences of self-heating.

Preparation of Vitamin E Intermediate from an Inexpensive Substrate by Selective Oxidation of Pseudocumene in HCOOH–H_2O_2 System

In this paper, 2,3,5-trimethyl-1,4-benzoquinone（TMBQ） was synthesized through the direct oxidation of1,2,4-trimethylbenzene（pseudocumene, TMB） in the HCOOH–H2O2 system. The influence ofthree active species was studied, including performic acid（PFA） generated in formic acid, peracetic acid（PAA） generated in acetic acid, and trifluoroperacetic（TFPA） acid generated in trifluoroacetic acid. The effects ofsulfuric acid and sodium formate addition were investigated, the overoxidation ofTMB was discussed, and the main reason for the decreasing selectivity was revealed. The oxidation ofTMB can be controlled and improved through adjusting the reaction temperature, mole ratio ofoxidant to substrate, and reactant concentration. The TMBQ yield of28% was achieved with a TMB concentration of0.2 mol/L, H2O2/TMB mole ratio of6：1, and reaction temperature 37 ℃. The selectivity of72% was obtained with a TMB concentration of0.2 mol/L, H2O2/TMB mole ratio of5：1, and reaction temperature of27 ℃. The reaction mechanisms were proposed and discussed based on the gas chromatography–flame ionization detection（GC–FID） and gas chromatography–mass spectrometer（GC–MS） results.

Acute Toxicity of Cadmium on the Antioxidant Defense Systems and Lipid Peroxidation in the Juveniles of Genetically Improved Farmed （GIFT） Tilapia Oreochromis Niloticus

Heavy metals pose a potential threat to aquatic organisms. In this study, a static-renewal acute toxicity test was conducted to investigate the effects of cadmium on the antioxidant defense systems （both enzymatic and non-enzymatic） and lipid peroxidaton in liver and gill tissues of juvenile GIFT tilapia Oreochromis niloticus. After 8 days of exposure to Cd （0, 0.016, 0.08, 0.4 and 2 mg/L）, livers accumulated significantly more Cd than gills. Catalase （CAT）, superoxide dismutase （SOD） and glutathione S-transferase （GST） activities were stimulated only at the highest concentration tested （2 mg/L）. Glutathione peroxidase （GPx） activity was stimulated in the gill while inhibited in the liver, these alternations in gill and liver showed a strong relationship with Cd levels in these tissues. This may indicate either a tissue-specific response of GPx to Cd or, most probably, a hormetic effect of Cd on GPx. Cd increased GSH levels and decreased the ratio GSSG/GSH in fish livers at 2 mg/L. Cd exposure resulted in an elevated level of MDA in the livers of fish at 2 mg/L, indicating that Cd caused lipid peroxidation. Taken together, the results demonstrated that Cd altered the enzymatic and non-enzymatic defensive systems and caused lipid peroxidation in O. niloticus at relatively high concentrations （compared to environmentally relevant concentrations）. In addition, the results implied that O. niloticus could tolerate high level of Cd in sites polluted by Cd.

Antioxidant system responses in two co-occurring green-tide algae under stress conditions

Green tides have occurred every year from 2007 to 2014 in the Yellow Sea. Ulva prolifera （Mtiller） J. Agardh has been identified as the bloom-forming alga, co-occurring with U. intestinalis. We observed distinct strategies for both algal species during green tides. U.prolifera exhibited a high abundance initially and then decreased dramatically, while U. intestinalis persisted throughout. The antioxidant system responses of these two macroalgae were compared in the late phase of a green tide （in-situ） and after laboratory acclimation. Lipid peroxidation and antioxidant system responses differed significantly between the two. Malondialdehyde and hydrogen peroxide contents increased significantly in-situ in U. prolifera, but not in U. intestinalis. In U. prolifera, we observed a significant decrease in total antioxidant ability （T-AOC）, antioxidant enzymes （SOD and Apx）, and non-enzyme antioxidants （GSH and AsA） in-situ. U. intestinalis showed the same pattern of T-AOC and SOD, but its Gpx, Apx, and GSH responses did not differ significantly. The results suggest that U. prolifera was more susceptible than U. intestinalis to the harsh environmental changes during the late phase of a Yellow Sea green tide. The boom and bust strategy exhibited by U. prolifera and the persistence of U. intestinalis can be explained by differences in enzyme activity and antioxidant systems.

Preparation of Sodium Cobalt Tetracarbonyl and Optimization of Process Conditions for Hydroesterification of Ethylene Oxide

In this paper, sodium cobalt tetracarbonyl （NaCo（CO）4） was synthesized by using sodium dithionite and zinc powder as the reduction system and cobalt hexahydrate acetate as the precursor in the presence of methanol solvent. Methyl 3-hydroxypropionate was synthesized via hydroesterification of ethylene oxide （EO） catalyzed by NaCo（CO）4. The influencing factors on the reaction results were discussed, including the different ligands, the molar ratio of solvent and ethylene oxide, the reaction temperature, the reaction time, and the reaction pressure. An optimal catalytic system was obtained by using 3-hydroxypyridine as the ligoad under reaction conditions covering a reaction temperature 65 ℃, a reaction time of 7 h, a reaction pressure of 6 MPa, and a methoaol/EO molar ratio of 3：2. Under the optimal conditions, the conversion of ethylene oxide was equal to 97.86%, while the selectivity and yield of methyl 3-hydroxypropionate reached 88.19% and 86.30%, respectively. Finally, the reaction mechanism of hydroesterification of ethylene oxide catalyzed by NaCo（CO）4 was proposed.

The Role of Formed Microorganism in Sludge on Processing of Wastewater Treatment

Several microorganisms such as bacteria, fungi, Protozoa, Rotifera, cystic amoeba and algae diagnosed in activated sludge aerobic （Rustumiya treatment plant） and anaerobic reactor. Results have shown a reduction in the turbidity rates when using activated sludge at Rustumiya plant of 76.3 to 2.653 NTU in pre-treatment and final tank respectively, also COD （chemical oxygen demand） amount reduced from 427.263 to 82 mg/L respectively, In addition, concentrations of phosphates and nitrates decreased from 12.083 to 8.426 mg/L and 3.59 to 2.43 mg/L respectively, by removing 30.2% and 32.3% respectively of the final tank. The ratio of ammonia removing was 89.6% for ammonia, reducing process from 1358 to 140 mg/L. Furthermore, sulfates concentration decreased from 30.883 to 23.337 mg/L. However, the system in the anaerobic reactor depends on non-aerated activated sludge. Results show turbidity reduced from 12.5 to 2 NTU in pre-treatment and final tank respectively, also the COD mount reduced from 191 to 130 mg/L, the percentage removal of 31.9%. In addition phosphates, nitrates and sulfates concentrations were decreased by using activated sludge from 17.15 to 8.15, 1.2 to 0.1 and 28 to 9.2 mg/L respectively. The ammonia concentration has reduced from 1.2 to 0. i mg/L where at a removal percentage of 90.9%.

Factors affecting biological denitrifying dephosphatation in anaerobic/anoxic/aerobic sequencing batch reactor

This study was conducted to verify and discuss the denitrifying dephosphatation under different levels of nitrate concentration and retention time of anoxic/aerobic process in a Sequencing Batch Reactor (SBR). The results of tests demonstrated that there were two kinds of phosphorus-accumulating organisms (PAOs) in the biological excess phosphorus removal (BEPR) system. One was non-DNPAOs that could only use oxygen as terminal electron acceptors, the other was denitrifying PAOs (DNPAOs) that could use both nitrate and oxygen as terminal electron acceptors. Phosphorus uptake efficiency could be attained under anoxic period ranging from 28.7%-96.7% in an anaerobic/anoxic/aerobic system. Experimental results showed that nitrate concentration and retention time of anoxic/aerobic process were the key factors affecting the course of denitrifying dephosphatation.

Recent advances in Ni-Al bimetallic catalysis for unreactive bond transformation

Ni-Al bimetallic catalysis proves to be an efficient catalytic strategy for unreactive bond transformations. Recently, chiral bifunctional ligands, especially amphoteric secondary phosphine oxide(SPO) ligand, are used for a more powerful synergistic effect in the bimetal-catalyzed reactions, providing not only milder reaction conditions and higher reactivity but also excellent reaction selectivity. Herein, we give a brief review on the development of Ni-Al bimetallic catalytic system and highlight recent advances in enantioselective Ni-Al bimetallic catalysis for unreactive bond transformation.