SO_3磺化法合成PNTS新工艺的研究

本文采用正交设计及方差分析法,确定了 SO_3磺化法合成 PNTS 新工艺的最佳工艺条件;并从技术及经济方面将新工艺同国内现有的生产老工艺进行了分析对比。     

Degradation of p-nitrotoluene by 03/H2 02 process and oxidation mechanism

The degradation of p-nitrotoluene by O2/H2O2 process in a bubble contact column was investigated.Effects of the molar ratio of hydrogen peroxide to ozone, pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2 O2/O3 molar ratio for the degradation of p-nitrotoluene was around O. 6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-metbyl-2-nitrophenol, 2-methy1-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl) -2-nitro phenol, acetic acid, 2-methylpropanc diacid and 2-(hydroxylmethyl) propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydrexy intermediate pathway. Then unstable polybydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.     

Degradation of p-nitrotoluene by O3/H2O2 process and oxidation mechanism

The degradation of p-nitrotoluene by O3/H2O2 process in a bubble contact column was investigated. Effects of the molar ratio of hydrogen peroxide to ozone,pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2O2/O3 molar ratio for the degradation of p-nitrotoluene was around 0.6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-methyl-2-nitrophenol, 2-methyl-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl)-2-nitro phenol, acetic acid, 2-methylpropane diacid and 2-(hydroxylmethyl)propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydroxy intermediate pathway. Then unstable polyhydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.     

对硝基苯甲酸新工艺的研究

以乙酸作溶剂,乙酸钴－ 溴化钠为复合催化剂,对硝基甲苯空气氧化制备对硝基苯甲酸。考察了压力、催化剂用量、反应温度、母液套用对反应的影响。试验表明,当反应压力为２－９４ ＭＰａ 、ｍ（ 对硝基甲苯）／ ｍ（ 乙酸）／ ｍ（ 乙酸钴四水合物）／ ｍ（ 溴化钠） ＝ ６０／２００／４／０－５２ 、反应温度１３０ ～１３５ ℃、反应时间５ ｈ 、尾气流量０－３ ｍ ３／ｈ 、连续套用母液６次时,对硝基苯甲酸的总收率达９４－７ ％ ,产品熔点２４１ ～２４２ ℃,产品质量分数９９－９ ％ 。     

硝硫磷混酸对甲苯一硝化选择性的影响及工艺过程研究

以甲苯为原料,考察了硝硫磷混酸对甲苯一硝化选择性的影响,结果表明:在保证硝化能力的前提下,水的质量分数以20%为宜,磷酸的引入明显降低了邻对比,提高了对硝基甲苯的选择性。利用响应面软件对间歇工艺条件进行了优化,适宜的工艺条件为硝酸/硫酸/磷酸/水(质量比)=0.1∶0.29∶0.41∶0.2,加料温度40℃,加料时间30min,反应温度60℃,反应时间180min,硝化比1.19,搅拌速率330r/min,在此条件下甲苯转化率为99.28%,邻对比1.31,对硝基甲苯收率41.55%。同时对静态混合管式连续选择性硝化工艺进行初步探索,进行了相同反应时间条件下的间歇对照试验,结果表明,采用静态混合反应技术后的硝硫磷混酸硝化过程,可以提高甲苯转化率,强化传质传热效果。     

氧气液相氧化对硝基甲苯制取对硝基苯甲酸的研究──Ⅱ:碱浓度对对硝基苯甲酸收率的影响

研究了碱浓度对氧气液相氧化对硝基甲苯制取对硝基苯甲酸的影响,发现对硝基苯甲酸的收率随着碱浓度的增加而增加。当碱浓度为４．８ｍｏｌ／Ｌ时,以甲醇为溶剂,在５０℃、２．０ＭＰａ氧压下反应１２ｈ可获得８１．１％的对硝基苯甲酸收率,粗品纯度可达９８．０％以上。     

3,4-二甲基苯胺的合成研究

分别以邻二甲苯和对硝基甲苯为起始原料,通过两种不同方法制备标题化合物。邻二甲苯经酰化、成肟、贝克曼重排、水解得到目标产物,纯度达98%,总收率53%。以对硝基甲苯为原料,经N-(2-甲基-5-硝基苄基)乙酰胺中间体合成标题化合物,纯度达99%,总收率50%。产物均经红外、核磁、质谱确认结构。     

甲基对苯二酚合成工艺的改进

针对甲基对苯二酚合成工艺路线较长、加水量较大、能耗较高、不易操作等问题进行了进一步研究。根据反应物系中各组分物性特点，通过正交设计和平行实验使加水量减少为原工艺的1／2，并省去了减压蒸馏和萃取工序，使生产周期缩短为原工艺路线的1／3，大大降低了能耗，简化了操作，显著降低了生产成本，更易于工业化实施。     

新型镍催化剂催化对硝基甲苯加氢的研究

研究了对硝基甲苯乙醇混合溶剂中加氢生成对甲基环己胺,重点制备了Ni-Nd/Al_2O_3为催化剂,并对其催化剂活性进行了评价以及对于反应历程做了说明。     

ML（Ni3．69Co0.72Mn0．35Al0．24）贮氢合金催化氢化对硝基甲苯的研究

采用掺杂ML（Ni3．69Co0.72Mn0．35Al0．24）贮氢合金形成的氢化物作为氢源及催化剂,加氢还原对硝基甲苯生成对甲苯胺进行了研究。利用GC—MS和GC分别对产物进行定性和定量分析,同时用XRD对合金进行了研究。结果表明：该催化剂可以在温和条件下将对硝基甲苯加氢还原成对甲苯胺,未检测到副产物的产生,对甲苯胺选择性高达100％,且反应后催化剂与反应体系容易分离。并详细探讨了催化剂用量、不同溶剂、反应温度和反应时间等对反应的影响。结果表明：催化剂的含氢量与催化剂的活性密切相关,溶剂的性质对反应有明显影响,以无水乙醇为溶剂时催化剂性能最好,重复使用5次仍具有较高的催化活性。