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吸附法脱除及回收焦化粗苯中噻吩的研究
Thiophene Removal and Recovery from Coking Crude Benzene by Adsorption Method
【作者】 田仁亮;
【导师】 王光辉;
【作者基本信息】 武汉科技大学 , 化学工艺, 2011, 硕士
【摘要】 焦化粗苯中都含有一定量的噻吩,如不分离会严重影响焦化苯产品的质量。噻吩也是珍贵的化工原料,实现对焦化粗苯中噻吩的分离与回收,将产生较大经济价值。因此本论文对用吸附法脱除及回收焦化粗苯中噻吩进行了研究。本论文以NaY分子筛为原料,用离子交换法制备了CeY分子筛;并对CeY分子筛用等体积浸渍法制备了不同Ce浸渍量的吸附剂Ce-CeY。用X射线粉末衍射(XRD)、氮吸附实验和傅立叶变换红外光谱(FT-IR)对所制备的吸附剂的结构进行了表征,并对噻吩吸附机理进行了研究。还就噻吩的回收、吸附剂的再生与循环利用进行了初步研究。研究结果表明:CeY分子筛中,Ce(Ⅳ)提供了丰富的吸附活性位,可以和噻吩形成π络合、S-Ce键配合及氢键作用;浸渍的Ce生成CeO2,分散在分子筛孔道内壁,造成吸附剂Ce-CeY孔径缩小,对噻吩具有分子尺寸选择作用。随着Ce浸渍量的增加,吸附剂的孔径逐渐缩小,吸附剂选择吸附噻吩性能先增大后减小。当温度为30℃、吸附剂用量8.5 %Ce-CeY(g) /模拟液(ml)为1/14、吸附时间超过120 min时,吸附剂8.5 %Ce-CeY的噻吩脱除率接近100 %。以二甲基亚砜为溶剂,用溶剂洗涤法可以实现对噻吩的回收,噻吩的收率为30 %。用直接焙烧对吸附剂进行再生,再生后的吸附剂选择吸附噻吩性能和原吸附剂基本一样。重复利用吸附剂三次,吸附剂噻吩脱除率仍然能保持80 %以上。
【Abstract】 The high thiophene content in coking crude benzene has seriously affected quality of the benzene product. Thiophene was also valuable chemical material, so it would have a great economic value to thiophene removal and recovery. Therefore, the thiophene removal and recovery from coking crude benzene by adsorption method were studied in this dissertation.Adsorbents Ce-CeY of different Ce impregnation amount prepared by incipient-wetness impregnation with zeolite CeY, which be prepared by ion exchanging with NaY zeolite, were investigated by XRD, Nitroge Adsorption Experiment and FT-IR. The thiophene recovery, adsorbent regeneration and recycling were also studied.The results indicated that Ce(Ⅳ) of CeY created a great deal of active site which could beπcomplexation, S-Ce interaction and hydrogen bonding with thiophene. Simultaneously, the pore size of adsorbents became narrowed due to the dispersion of CeO2 formed by impregnation of Ce on zeolite, which could be selective adsorption to thiophene for different molecular size. The pore size was narrowed, the thiophene selective adsorption performance was increased, and then decreased, with the Ce impregnation amount increasing. The thiophene removal of 8.5 %Ce-CeY could be 100 %, in the condition of 30℃, 1/ 14(adsorbent(g)/ model liquid(ml) ) and 120 min(contact time).Thiophene could be recovered whose yield was 30 % by solvent washing method, using DMSO as solvent. The thiophene removal of adsorbent regenerated by direct calcination was essentially as the original adsorbent. The thiophene removal could still maintain more than 80 % after repeated three times.
【Key words】 thiophene; coking crude benzene; selective adsorption; CeY zeolite; thiophene recovery;