水蒸汽处理丝光沸石上萘择形异丙基化反应

Shape Selective Isopropylation of Naphthalene on Steam Treated Mordenite

采用常压高温水蒸汽处理的方法对丝光沸石(HM)进行改性,并用高压微型固定床反应器对改性丝光沸石进行评价,以萘的转化率和产物的选择性表征催化剂的萘异丙基化反应性能,研究了不同水蒸汽处理条件对萘异丙基化反应的影响。结果表明,提高水蒸汽处理温度和处理时间,萘的转化率降低,2,6-DIPN的选择性提高。而处理空速增加,萘的转化率和2,6-DIPN的选择性均降低。水蒸汽处理有利于减少强酸中心的数目,改变丝光沸石外表面酸性,抑制副反应的发生。适宜的水蒸汽处理条件为:温度500℃、时间1h、空速0.5h-1。HM经高温水蒸气处理后,β位及β,β位异丙基萘的选择性有所提高,同时2,6-DIPN选择性明显增大,催化剂的稳定性提高。并用NH3-TPD表征了催化剂的酸性。

The reaction of isopropylation of naphthalene over mordenites carried out in a high-pressure fixed-bed micro-reactor, which were treated with steam under different conditions, was studied. Based on the characteristics of the conversion of naphthalene and selectivity to products, the effect on naphthalene's reaction under different steam treatment was studied. The results show when temperature and time of steam treatment increase, the conversion of naphthalene decreases, whereas the selectivity of 2,6-DIPN increases; but the increasing of WHSV of steam treatment causes both the conversion of naphthalene and the selectivity of 2,6-DIPN decrease. High-temperature steam treatment helps to decrease numbers of strong acid centers and improve the selectivity of β-isopropylnaphthalene (IPN) and β,β-diisopropylnaphthalene (DIPN) ,especially for 2,6-DIPN, and strengthens the stability of the mordenite. Steam treatment could change the external acidity of mordenites and restrain side-reactions. The condition of steam treatment (T=500 ℃,WHSV=0.5 h-1, t=1 h) may be optimal for naphthalene isopropylation on modenite. And acidity on mordenite had been investigated by means of NH3-TPD.