Hβ沸石修饰的复合氧化物对苯酚羟基化反应的催化作用  

The catalysis of composite oxides modified by Hβ zeolite on phenol hydroxylation

作　　者：张信芳[1] 张敬畅[2] 张光明[1] 聂永丰[1] 陈晓冬[3] 

机构地区：[1]清华大学深圳研究生院,广东深圳518055 [2]北京化工大学理学院,北京100029 [3]中国石化北京燕山分公司研究院,北京102500

出　　处：《工业催化》2004年第9期22-27,共6页Industrial Catalysis

基　　金：国家自然科学基金项目 (批准号 :2 0 0 760 0 4) ;中国石化股份有限公司燕山分公司资助项目

摘　　要：采用不同硅铝比的Hβ沸石对铁基复合金属氧化物催化剂进行了修饰,发现复合氧化物催化体系中掺入适量具有特定结构的Hβ沸石,可以提高催化剂的活性,缩短甚至消除羟基化反应诱导期,避免由于未反应过氧化氢的积累增加反应器运行的风险,提高过氧化氢有效利用率和目标产物选择性。但过多的Hβ沸石导致苯酚和苯二酚缩合生成不溶于水的焦油,降低了羟基化反应的目标产物选择性。比较合适的修饰用Hβ沸石包括Hβ 80、Hβ 63和Hβ 48。比较好的Hβ 80沸石掺入质量分数为7%,以7%Hβ沸石修饰的Fe Cu Sn Zn O/γ Al2O3复合氧化物作催化剂,反应温度65℃、反应时间30min、苯酚5 3g、溶剂水10 0g、m(苯酚)∶m(催化剂)=294、n(过氧化氢)∶n(苯酚)=0 33时,反应诱导期不到1min,苯酚转化率22 3%,苯二酚选择性91 9%,过氧化氢有效利用率62 1%。Iron-based mixed oxides catalysts were modified by Hβ zeolites with different SiO_2/Al_2O_3 ratio. It was found that activity of the catalysts was enhanced after the modification and induction period for phenol hydroxylation was greatly shortened or even disappeared,and thus risk of over-accumulation of unreacted hydrogen peroxide was avoided, and utilization efficiency of hydrogen peroxide and selectivity to desired products were improved. However, excessive Hβ zeolite in the mixed oxides catalysts resulted in formation of water-insoluble tar via condensation of phenol and hydroquinone and decreased the selectivity to desired products. Favorable zeolites for the modification include Hβ-80, Hβ-63 and Hβ-48 (with SiO_2/Al_2O_3 molar ratio of 80, 63 and 48, respectively) and preferable doping quantity of Hβ-80 zeolite is 7%( mass fraction). Phenol conversion of 22.3% and selectivity to hydroquinone of 91.9% were attained over Fe-Cu-Sn-Zn-O/γ-Al_2O_3 catalyst modified by 7.0%(mass fraction) Hβ zeolite(silica/alumina molar ratio =80) under the following condition: 65 ℃, reaction time 30 min, phenol 5.3 g, catalyst 0.018g, hydrogen peroxide/phenol (molar ratio) = 0.33, water/phenol(mass ratio) = 2.0. The induction period was less than 1 min.

关 键 词：苯酚 羟基化 HΒ沸石 复合氧化物 修饰 

分 类 号：TQ424.25[化学工程] TQ243.12