在實際操作過程中,鄰苯二甲酸酐氣體冷凝蒸餾過程中,可有效去除馬來酸酐、檸檬酸酐、苯、鄰二甲苯、苯甲酸、鄰甲苯酸等雜質(zhì)。在催化劑使用初期,蒽醌及其同系物等重雜質(zhì)較少。蒸餾后可以減少到可以接受的水平(但是后期用于催化劑、催化劑性能差,很難單獨的四氯苯酞進一步增加一代,代蒽醌及其同系物和其他重型說,通過蒸餾不能徹底,影響鄰苯二甲酸酐產(chǎn)品融化顏色數(shù)量和顏色將增加的熱穩(wěn)定性。酞本身是無色“即使添加量高達0.5%),但對熱穩(wěn)定性的影響的顏色數(shù)量大得多(這表明,本質(zhì)上是不穩(wěn)定的,容易轉(zhuǎn)換成顯色物質(zhì),鄰苯二甲酸酐的顏色數(shù)量,特別是熱穩(wěn)定性的顏色數(shù)量大幅增加。
In the actual operation process, the impurities such as maleic anhydride, citric anhydride, benzene, o-xylene, benzoic acid and o-toluic acid can be effectively removed in the process of condensation distillation of o-phthalic anhydride. In the early stage of catalyst use, anthraquinone and its homologues have less heavy impurities. After distillation, it can be reduced to an acceptable level (but in the later stage, it is difficult to increase the generation of Tetrachlorobenzene phthalein alone due to poor performance of catalyst and catalyst. Anthraquinone and its homologues and other heavy-duty theories cannot be completely removed by distillation, which will affect the quantity and thermal stability of the melting color of phthalic anhydride products. Phthalide itself is colorless "even if the amount of addition is as high as 0.5%), but the number of colors that affect the thermal stability is much larger (this shows that it is unstable in nature, easy to convert into chromogenic substances, and the number of colors of phthalic anhydride, especially the number of colors that are thermally stable, increases significantly.
因為酞和鄰苯二甲酸酐是很難有效和完全獨立的,所以在實際業(yè)務流程盡可能地控制酞,確保鄰苯二甲酸酐的質(zhì)量是非常重要的,當然,高性能催化劑的使用可以減少酞“高負載的催化劑的使用可以提高設備的操作能力。但是,隨著裝置的運行,高性能催化劑的活性會慢慢降低,同時鄰苯二甲酸的產(chǎn)生量也會相應增加(反應溫度升高后,生成的鄰苯二甲酸會進一步被氧化)。在催化劑活性大幅度降低之前,通過降低裝置的負荷和運行能力,也可以保證鄰苯二甲酸酐的質(zhì)量。在催化劑使用的后期,當鄰苯二甲酸和重雜質(zhì)蒽醌及其同系物的產(chǎn)量增加到一定程度時,需要更換催化劑以保證鄰苯二甲酸酐的質(zhì)量。
Because phthalic acid and phthalic anhydride are difficult to be effective and completely independent, it is very important to control the production of phthalic acid as much as possible in the actual business process to ensure the quality of phthalic anhydride. Of course, the use of high-performance catalyst can reduce the use of catalyst with high load for the production of phthalic acid, which can improve the operation capacity of the equipment. However, with the operation of the unit, the activity of the high-performance catalyst will slowly reduce, and the amount of phthalic acid produced will also increase correspondingly (after the reaction temperature increases, the phthalic acid produced will be further oxidized). Two kinds of two kinds of catalysts will be used in the production of phthalic acid. The quality of phthalic anhydride can also be guaranteed by reducing the load and operation capacity of the unit before the catalyst activity is greatly reduced. When the output of phthalic acid, anthraquinone and their homologues increases to a certain extent, the catalyst needs to be replaced to ensure the quality of phthalic anhydride.
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