对二甲苯富氧氧化工艺研究

Process of p-Xylene Oxidation with Oxygen-Enriched Air

对BP-Amoco工艺氧化反应器进行了改进,以富氧空气为氧化剂对对二甲苯(PX)进行氧化反应,研究了反应器结构对氧化反应的影响,确定最佳的PX富氧氧化反应器结构为:反应器内有双层导流筒,进气口在导流筒外侧,进液口在导流简内侧,进气管内径10 mm。同时考察了富氧空气中的氧气含量、反应压力对氧化反应的影响,得到了适宜的工艺条件:富氧空气中氧气体积分数为24 0%～27.0%,反应压力1.50 MPa,反应温度195.0℃,搅拌转速550 r/min,催化剂中w(Co)=230 mg/kg、w(Mn)=340 mg/kg、w(Br)=760mg/kg,进液流量55.0 kg/h,进气流量140～200 L/min,w(HAc+H_2O):w(PX)=3.7。在此条件下,PX氧化反应效果最好,产物中目标产物对苯二甲酸含量高于普通空气氧化法,而主要副产物对羧基苯甲醛含量低于普通空气氧化法。

The BP-Amoco oxidation reactor was revamped by installing two draft tubes in it, with air inlets outside draft tube II , liquid feed inlets inside draft tube II and inner diameters of the air inlets 10 mm. The revamped reactor was used in the oxidation of p-xylene（PX） with oxygen-enriched air to terephthalic acid. The reactor structure was designed according to the experimental results of the PX oxidation. The effects of O2 content in the oxygen-enriched air and reaction pressure on the oxidation were studied. Under the optimum reaction conditions of O2 volume fraction in the oxygen-enriched air 24. 0% -27.0%, flow rate of the oxygen-enriched air 140 -200 L/min, flow rate of liquid feed 55.0 kg/h, reaction pressure 1.50 MPa, reaction temperature 195.0 ℃, stirring speed 550 r/min, w（HAc ＋H2O） ： w（PX） 3.7, and w（Co） 230 mg/kg, w（Mn） 340 mg/kg and w（Br） 760 mg/kg in the catalyst, the terephthalic acid content and the main byproduct 4-carboxy benzaldehyde content in the oxidation products were higher and lower than those obtained by common air oxidation, respectively.