共查询到20条相似文献,搜索用时 62 毫秒
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研究改进了草酸电解还原制备乙醛酸中的阳极材料、隔膜及电解工艺。实验 :本研究选用隔膜电解法。阳极选用在酸性溶液中有良好导电性、有高的析氧过电势及低的阳极极化率 ,同时价格较便宜的钛基氧化铱电极 ,阴极用铅板。隔膜材料直接影响电解反应能否顺利进行及产率大小 ,在全氟、HF -10 1高性能均相、聚氯乙烯 3种阳离子交换膜中用实验方法进行电解草酸产率比较后选定HF - 10 1高性能均相阳离子交换膜。通过实验分析确定了电解工艺 :电流密度 5 0 0A m2 ,槽电压 4 5V ,电解温度2 0℃ ,阳极电压 - 1 32V ,阳极草酸浓度始终维持质量… 相似文献
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改性海藻酸钠/壳聚糖双极膜成对电解制备乙醛酸 总被引:2,自引:0,他引:2
以镍网电极-改性海藻酸钠/壳聚糖双极膜(Ni-mSA/mCS BM)作为阴阳两室间的隔膜,利用双极膜的中间界面层水解离特性成对电解制备乙醛酸.水解离特性分析结果表明,双极膜中水解离后生成的H 透过mSA阳离子膜进入阴极室中,可及时补充草酸电还原生成乙醛酸过程中的H 消耗;OH(透过mCS阴离子膜进入阳极室中,与乙二醛电氧化生成乙醛酸过程中产生的H 结合生成H2O,可促进正向反应的速度.以饱和草酸和盐酸的混合液作阴极液,以10%乙二醛和10%KBr的混合液作阳极液,镍网为阴极,二氧化铅为阳极,在电流密度为20 mA·cm-2常温下电解,阴极电流效率达82.9%,阳极电流效率达75.7%,电解电压低于2.7 V. 相似文献
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利用阳离子膜,以K2CrO4电解结晶制备K2Cr2O7,考察了电流密度、温度、阴极液KOH浓度、阳极液K2CrO4浓度等因素对转化率、电流效率和直流能耗的影响;研究了K2Cr2O7不同浓度、不同转化率下的结晶纯度和收率及搅拌速率、降温速率和晶种加入量等对晶体粒度分布和形貌的影响. 结果表明,最佳电解工艺条件为:电流密度0.2 A/cm2,电解温度80℃,阴极液KOH浓度50 g/L,阳极液K2CrO4浓度400 g/L. K2Cr2O7转化率大于90%时,结晶纯度不低于99.8%. 优化的结晶条件为:溶液初始K2Cr2O7浓度500 g/L,搅拌速率300 r/min,降温速率0.5℃/min,不添加晶种. 所得产品符合GB 28657-2012要求. 相似文献
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操作条件对离子膜性能的影响 总被引:1,自引:1,他引:0
由西安西化热电化工有限责任公司离子膜电解装置10年来的运行状况,总结出影响离子膜性能的8个主要因素有:盐水质量、阴极液浓度、阳极液浓度、电解液温度、电流密度、阳极液酸度、电解液流量和开停车时的洗槽。 相似文献
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通过单因素实验考察了四甲基氢氧化铵的电解工艺。以钛基镀铱板为阳极,不锈钢为阴极,在电解槽中恒电流密度电解提纯四甲基氢氧化铵,主要考察了电解工艺中离子交换膜种类、原料浓度、电解温度和电流密度对电流效率的影响。当采用上海上化水处理厂3361为阳离子交换膜,在原料室四甲基氢氧化铵浓度25%、电解液温度50℃、电流密度8 ASD(A/dm2)时,电流效率可达66.74%,产品中金属离子杂质总含量从25×10-6降至0.8×10-6,氯离子浓度从0.65×10-6降至0.01×10-6。采用等离子体发射光谱仪(ICP-AES)、分光光度计对产品四甲基氢氧化铵进行表征。 相似文献
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Daniel Swern A. J. Stirton J. Turer P. A. Wells 《Journal of the American Oil Chemists' Society》1943,20(11):224-226
Summary Fat-soluble fatty acid monoesters of 1-ascorbic acid (vitamin C) and d-isoascorbic acid have been prepared from lauric, myristic,
palmitic, and stearic acids in 40–50 per cent yields.
Evidence has been presented to show that only the primary hydroxyl group of each of the ascorbic acids has been esterified.
Antioxidant properties of these esters are being studied.
Preliminary tests on the esters have indicated that they may have useful properties as interfacial modifiers. 相似文献
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This study reports the electrohydrodimerization of pyruvic acid to 2,3-dimethyltartaric acid in sulphuric acid medium (0.5 M H2SO4) on a lead cathode. The main products detected were lactic acid and 2,3-dimethyltartaric acid. The selectivity towards the formation of 2,3-dimethyltartaric acid was studied vs. pyruvic acid concentration in sulphuric acid solution, at −1.1 V vs. MSE. The best selectivity of 2,3-dimethyltartaric acid reached 69% for an initial concentration of 1.7 M pyruvic acid. The yield of pyruvic acid was 84%. 相似文献
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Shigenobu Kishino Jun Ogawa Yoriko Omura Kenji Matsumura Sakayu Shimizu 《Journal of the American Oil Chemists' Society》2002,79(2):159-163
After screening 14 genera of lactic acid bacteria, Lactobacillus plantarum AKU 1009a was selected as a potential strain for CLA production from linoleic acid. Washed cells of L. plantarum with high levels of CLA production were obtained by cultivation in a nutrient medium with 0.06% (wt/vol) linoleic acid (cis-9,cis-12-octadecadienoic acid). Under the optimal reaction conditions with the free form of linoleic acid as the substrate, washed
cells of L. plantarum produced 40 mg CLA/mL reaction mixture (33% molar yield) from 12% (wt/vol) linoleic acid in 108 h. The resulting CLA was
a mixture of two CLA isomers, cis-9,trans-11 (or trans-9,cis-11)-octadecadienoic acid (CLA1, 38% of total CLA) and trans-9,trans-11-octadecadienoic acid (CLA2, 62% of total CLA), and accounted for 50% of the total FA obtained. A higher yield (80% molar
yield to linoleic acid) was attained with 2.6% (wt/vol) linoleic acid as the substrate in 96 h, resulting in CLA production
of 20 mg/mL reaction mixture [consisting of CLA1 (2%) and CLA2 (98%)] and accounting for 80% of total FA obtained. Most of
the CLA produced was associated with the cells (ca. 380 mg CLA/g dry cells), mainly as FFA. 相似文献
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以正丁醇为内标,氢火焰离子化检测器测定,建立了气相色谱法直接进样测定乳酸催化制备丙烯酸反应液中乳酸和丙烯酸含量的方法。在载气(N2)流速为30mL·min^-1,氢气流速为88mL·min^-1,空气流速为300mL·min^-1,进样器和离子室温度为160℃,柱温为150℃的10%PEG-20M(3m×3mml填充柱上能实现很好的分离。乳酸和丙烯酸测定方法的线性相关系数分别为0.9994和0.9996,相对标准偏差分别为O.74%和0.56%,平均回收率分别为97.35%-1197.60%,检出限分别为8.62mg·L^-1和1.21mg·L^-1方法简便、快速、准确。 相似文献
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开发研究了氯乙酸副产盐酸的精制工艺及盐酸中有机杂质的紫外分光光度分析方法。副产盐酸经酸洗、吸收、蒸馏得高纯盐酸。中试结果表明 ,工艺合理 ,精制盐酸达到GB 32 0 - 93规定的工业用合成盐酸标准 相似文献
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介绍炼厂酸性气制硫酸装置的工艺过程。由于实供气源与设计值有较大出入,二氧化碳浓度偏高, 并且夹带烃类物质较多,使装置无法正常运行。通过对酸性气进行预处理后,一次开车成功,各项工艺指标均达到设计要求,遇酸性气流量突降时可补充适量硫磺,维持正常生产。 相似文献
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Edwin S. Olson 《Journal of the American Oil Chemists' Society》1977,54(2):51-53
The performic acid oxidation of linoleic acid has been shown to form 9,12-dihydroxy-trans-10,11-methylene-heptadecanoic acid (I) after hydrolysis of the formate ester. A sequence of reactions led to the identification of dimethyl-trans-1,2-cyclopropanedicarboxylate by gas liquid chromatography. Spectroscopic evidence is presented for thetrans geometry in I. Failure of the monoepoxide of linoleic acid to give the formate ester of I suggests the alternative that a homoallylic carbonium ion is formed directly upon attack of the peroxide reagent. 相似文献