草酸的生产方法及其进展

草酸作为一种重要的化工原料,广泛用于药物生产、高分子合成、稀土元素提取以及织物漂白等工业,需求量日趋增加。草酸的合成方法有很多种,文章介绍了多糖氧化法、丙烯氧化法、乙二醇氧化法、一氧化碳偶联法、甲酸钠法,评述了各种方法的优缺点。并对我国草酸工业的发展提出了建议。     

氧化法草酸工艺较合成法草酸工艺的优势所在

从原料、工艺路线,设备选型,经济效益及环境保护等几个方面介绍了氧化法草酸和合成法草酸的生产工艺过程,并对两种工艺进行了比较,得出了氧化法草酸工艺的优势所在。     

乙醛酸的合成及在医药中的应用

乙醛酸的合成基本分为2大类，化学合成和电化学合成，其中实现工业化生产的为化学合成中的乙二醛硝酸氧化法、顺酐臭氧氧化法和电化学合成中的草酸电解还原法。     

氧化法生产草酸的工艺研究

对氧化法生产草酸的工艺条件和工艺过程控制进行了讨论,确定了最佳反应条件。     

液相氧化剂氧化法制备六氟环氧丙烷的研究进展

简要介绍了六氟环氧丙烷的物化性质、应用及合成工艺,重点介绍了过氧化氢氧化法和次氯酸钠氧化法氧化六氟丙烯制备六氟环氧丙烷的工艺研究。相比于其他六氟环氧丙烷的制备方法,液相氧化剂氧化法具有反应条件温和、反应速率大、产物选择性高且不存在氧爆风险等优势,一直以来备受人们关注。     

高铁酸盐制备方法研究进展

高铁酸盐是一种环境友好的强氧化剂,在水处理、有机合成和超铁电池等方面具有重要的潜在应用价值.综述了近20 a高铁酸盐主要合成方法的研究进展及其特点,包括:熔融法、次氯酸盐氧化法和电化学氧化法,其中电化学氧化法又包括液态高铁酸盐电合成法和固态高铁酸盐直接电合成法.指出:高铁酸钾直接电合成法以其操作简单、原材料消耗少、成本低、可循环生产、工艺绿色环保等优点而成为最有可能工业化应用的合成方法,同时指出了其发展方向.     

淀粉氧化制草酸的新工艺研究

研究了用氧化法制备草酸中产生的富二氧化氮气尾气再次氧化淀粉制备草酸的工艺，找出了最佳工艺条件，草酸收率为５５％。     

氧化法制草酸母液的全部回用

本文探讨了淀粉硝酸氧化法制草酸母液的全部回用问题。试验结果表明,草酸母液的闭路循环利用,不但能提高草酸的收率,而且简化了生产工艺及设备,减轻三废处理,是解决氧化法生产草酸的有效方法。     

化学氧化法制备草酸工艺述评

综述了化学氧化法制备草酸工艺过程的四个方面。从氧化剂种类、原料来源、加料顺序和废气治理四个方面分别进行了分析,对该工艺过程中出现的问题以及解决的方法进行了探讨,指出了今后的研究发展趋势。     

碳酸二苯酯的提纯工艺进展

本文按合成碳酸二苯酯的三种方法－－光气法、酯变换法和氧化羰化法，详细介绍了碳酸二苯酯的提纯工艺。     

葡萄糖氧化制草酸

针对目前国内草酸生产成本高、工艺复杂等缺点,开展了葡萄糖氧化制草酸的工艺研究。以蔗糖、葡萄糖等碳水化合物为原料,在硫酸、硝酸和水的混合物为氧化介质的反应体系中氧化为草酸。在优化工艺条件下:硫酸的浓度为50%,反应温度60～65℃,m(葡萄糖)∶m(硝酸)=1∶3.2,催化剂的加入量为0.05%(以葡萄糖计,m/m),加料时间6h,母液循环使用。每吨葡萄糖可产草酸1.65～1.75t,收率达90%以上。     

A catalyst that uses a rhodium phthalocyanin for oxalic acid oxidation and its application to an oxalic acid sensor

Rhodium phthalocyanin was shown to exhibit high catalytic activity toward oxalic acid oxidation in terms of the onset potential and current density. The onset potential for the oxidation of oxalic acid is much lower than those of the previous electrodes. The substrate specificity and the effect of anion were also examined. The results suggest that oxalic acid would first coordinate to the Rh center in the catalytic cycle. An amperometric sensor for oxalic acid was constructed using Rh phthalocyanin. This sensor worked at a low applied potential (0.75 V vs. a reversible hydrogen electrode). The limit of detection of the sensor reached 1 μM.     

草酸生产技术现状及市场前景分析

首先介绍了碳水化合物法、丙烯氧化法、甲酸钠法、一氧化碳偶联法及乙二醇氧化法等几种草酸的生产技术及其优、缺点和新进展。随后对草酸的市场前景进行了分析,并以草酸在稀土行业应用的为例,结合一些政策性文件对其市场前景进行了重点分析。最后对国内的草酸生产企业如何提高核心竞争力提出了一些建议。     

甲苯液相氧化过程中结垢的原因及其影响因素

甲苯液相空气氧化是环境友好的苯甲酸生产工艺.在SNIA苯甲酸生产过程中,CoC2O4•2H2O的生成导致甲苯氧化过程产生严重的结垢现象,严重影响生产的正常运行.通过液相色谱对反应中间产物进行检测,发现有痕量的对苯二酚、马来酸、草酸生成.对生成CoC₂O₄•2H₂O的可能途径进行了分析和研究,结果表明,通过苯、甲苯及其衍生物氧化生成草酸是导致结垢的主要原因.通过改变反应物组成及操作条件,对反应温度、操作压力、空速、催化剂用量、苯含量以及含水量等因素对结垢的影响进行了研究.结果表明,当生成苯甲酸的目标反应受到抑制时,结垢明显加剧.随着反应体系中的苯含量或含水量的增大,其结垢加剧.当催化剂浓度低于100 μg•g^-1时,随Co含量的增大,其结垢减轻.当反应体系中无苯甲酸时,反应受到抑制,结垢严重.当空气鼓气量低于4.0×10-3 m³•min^-1时,随空气鼓气量的增大,其结垢减轻.操作压力对结垢的影响较小.反应温度低于155 ℃时,反应受到抑制同时结垢加剧.     

草酸的生产工艺及市场分析

介绍了甲酸钠法、碳水化合物氧化法、乙二醇氧化法、丙烯氧化法和一氧化碳偶联法等几种草酸工业生产方法,对其优缺点进行了对比。同时从制药行业、稀土加工业、精细化工行业及其他新兴行业对草酸的下游市场进行了详细分析,为草酸行业未来的发展提供了一些建议。     

Catalytic wet air oxidation of carboxylic acids at atmospheric pressure

Catalytic wet air oxidation of carboxylic acids (maleic acid, oxalic acid and formic acid) was carried out in a batch reactor operated at 160 psi or atmospheric pressure. Pt/Al₂O₃ and the sulfonated poly(styrene-co-divinylbenzene) resin were used as catalysts. Maleic acid was proved to be a refractory substance which could not be oxidized on the Pt/Al₂O₃ catalyst at all atmoshperic pressure, and needed high pressure and high temperature operation for its oxidation. On the contrary, oxalic acid and formic acid were readily oxidized into carbon dioxide and water at 353 K and atmospheric pressure. The pathways of maleic acid oxidation were proposed, and the conversion of maleic acid into oxalic acid was the rate-determining step. When the sulfonated resin catalyst was present together with the Pt/Al₂O₃ catalyst, maleic acid could be oxidized at 353 K and atmospheric pressure. The sulfonated resin catalyst was suggested to hydrolyze maleic acid into readily oxidizable compounds.     

加压氧化法生产草酸的工艺研究

本文针对传统氧化法生产草酸工艺中存在的硝酸用量大,得率低,NO_2,NO对环境产生污染等问题,在氧化罐内充入氧气,使氧化反应中产生的NO转化为NO_2。同时提高反应压力至0.16～0.20MPa,增加了NO_2在反应液中的溶解度,提高了硝酸的利用率,降低了生产成本,减少了废气对环境的污染。     

Degradation kinetics of recalcitrant organic compounds in a decontamination process with UV/H<Subscript>2</Subscript>O<Subscript>2</Subscript> and UV/H<Subscript>2</Subscript>O<Subscript>2</Subscript>/TiO<Subscript>2</Subscript> processes

In this study, degradation aspects and kinetics of organics in a decontamination process were considered in the degradation experiments of advanced oxidation processes (AOP),i.e., UV, UV/H₂O, and UV/H₂O,/TiO₂ systems. In the oxalic acid degradation with different H₂O₂ concentrations, it was found that oxalic acid was degraded with the first order reaction and the highest degradation rate was observed at 0.1 M of hydrogen peroxide. Degradation rate of oxalic acid was much higher than that of citric acid, irrespective of degradation methods, assuming that degradation aspects are related to chemical structures. Of methods, the TiO₂ mediated photocatalysis showed the highest rate constant for oxalic acid and citric acid degradation. It was clearly showed that advanced oxidation processes were effective means to degrade recalcitrant organic compounds existing in a decontamination process.     

The anodic behaviour of Ebonex® in oxalic acid solutions

A study of the oxidation of aqueous solutions of oxalic acid in various supporting electrolytes, at an Ebonex^® anode is reported. From data obtained by cyclic voltammetry, linear sweep voltammetry, chronopotentiometry, controlled potential coulometry and gas chramatography it has been shown that oxalic acid oxidation at an Ebonex^® anode, does not proceed, to any significant extent. Data collected using different electrolytes showed that sulphuric acid supported higher current densities at similar electrode potentials. Ebonex^® is essentially a selective oxygen evolver and is thus a suitable anode for the electroreduction of oxalic acid to glyoxylic acid in an undivided cell. The behaviour of a platinized titanium anode is also reported and this material has similar electrochemical characteristics to Ebonex^® in aqueous oxalic acid solutions.