Abstract Liquid phase selective homogeneous catalytic oxidation of stearic acid (SA) was carried out to obtain industrially important carbon neutral high-added value octadecanedioic acid (ODDA). The oxidation was carried using air, cobalt(II)-acetate, manganese(II)-acetate and HBr catalyst in acetic acid (AcOH) solvent at an elevated temperature and pressure. SA oxidation products were analyzed by gas chromatography–mass spectrometry (GC–MS), gas chromatography (GC) and CO2 analyzer, and SA was oxidized selectively to ODDA without producing CO2 and intermediates like alcohols, aldehydes and ketones. The effect of SA loading (5–20%), pressure (2.8–5.8 barg) and temperature (353–383 K) on ODDA yield was studied by varying one variable at a time. Central composite design assisted response surface methodology was employed to find (i) the optimal design of experiments involving several combination of cobalt(II)-acetate (Co: 0–700 ppm), manganese(II)-acetate (Mn: 0–700 ppm) and HBr (Br–: 0–1144 ppm) and (ii) the most influencing variable and interaction among the variables. The synergistic effect of cobalt(II)-acetate in presence of HBr was observed and suggested that SA oxidation proceeds via bromine-bromide cycle. The elevated temperature and pressure along with reduced SA loading enhanced the yield of ODDA. The maximum ODDA yield was found to be 90.5% and corresponding optimum cobalt (II), manganese (II) and bromide concentration were 600.4, 452.2 and 1016.6 ppm, respectively, at fixed SA:AcOH-10:90, pressure-2.8 barg and temperature-383 K. Finally, SA oxidation kinetic analysis was determined based on the pseudo-first order homogeneous catalysis and found to be kinetically controlled with an average activation energy 34.55 kJ mol−1. The proposed kinetic model fitted well with the time-variant experimental SA and ODDA concentration under varying operating condition with percent average absolute deviation less than 5.0%.

中文翻译：

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使用空气和过渡金属醋酸溴化物催化剂将硬脂酸选择性转化为高附加值十八烷二酸：动力学、途径和工艺优化

摘要 对硬脂酸（SA）进行液相选择性均相催化氧化，获得工业上重要的碳中性高附加值十八烷二酸（ODDA）。在升高的温度和压力下，在乙酸 (AcOH) 溶剂中使用空气、钴 (II)-乙酸盐、锰 (II)-乙酸盐和 HBr 催化剂进行氧化。SA 氧化产物通过气相色谱-质谱 (GC-MS)、气相色谱 (GC) 和 CO2 分析仪进行分析，并且 SA 被选择性氧化为 ODDA，而不产生 CO2 和中间体，如醇、醛和酮。通过一次改变一个变量来研究 SA 负载 (5–20%)、压力 (2.8–5.8 barg) 和温度 (353–383 K) 对 ODDA 产量的影响。采用中心复合设计辅助响应面方法来寻找 (i) 涉及钴 (II)-乙酸盐 (Co: 0–700 ppm)、锰 (II)-乙酸盐 (Mn: 0–700 ppm) 和 HBr (Br–: 0–1144 ppm) 和 (ii) 影响最大的变量和变量之间的相互作用。观察到在 HBr 存在下钴 (II)-乙酸盐的协同作用，并表明 SA 氧化通过溴-溴化物循环进行。升高的温度和压力以及减少的 SA 负载提高了 ODDA 的产率。发现最大 ODDA 产率为 90.5%，相应的最佳钴 (II)、锰 (II) 和溴化物浓度分别为 600.4、452.2 和 1016.6 ppm，在固定 SA:AcOH-10:90、压力为 2.8 barg 和温度-383 K。最后，SA 氧化动力学分析是基于准一级均相催化确定的，发现其被动力学控制，平均活化能为 34.55 kJ mol-1。所提出的动力学模型与不同操作条件下随时间变化的实验 SA 和 ODDA 浓度非常吻合，平均绝对偏差百分比小于 5.0%。