SO_4~(2-)/TiO_2-Al_2O_3固体酸催化剂的表征及其催化合成均苯四甲酸四异辛酯

用共沉淀法制备了系列SO42-/T iO2-A l2O3固体酸催化剂,用X射线衍射、NH3程序升温脱附、热重分析、X射线能谱、红外光谱、等温吸附等方法对SO42-/T iO2-A l2O3固体酸催化剂进行了表征。表征结果表明,SO42-/T iO2催化剂中加入A l可以阻止T iO2的晶化;增加固体超强酸表面酸强度和酸量;稳定催化剂表面的S,减少其在高温焙烧下的流失量;增大催化剂的比表面积。SO42-/T iO2-A l2O3固体酸催化剂在合成均苯四甲酸四异辛酯的反应中有很高的活性,在A l摩尔分数23.1%、焙烧温度400℃时,催化活性最好,反应2h后,转化率达到98.2%。

Characterization of SO42-/TiO2 -Al2O3 Solid Acid Catalyst and Its Catalytic Activity in Tetraoctyl Pyromelliate ( Terra - 2 - Ethylhexyl Pyromellitate) Synthesis

A series of sulphated Al_2O_3-TiO_2 mixed oxides were prepared and used as catalysts in synthesis of tetraoctyl pyro-mellitate.The catalysts were characterized by means of XRD,NH_3-TPD,TG,IR,BET and EDS methods.From XRD pattern it was found that crystallization of TiO_2 was inhibited with addition of Al and kept smaller sizes crystals.As a result,the specific surface area of SO~(2-)_4/TiO_2-AlO_2 catalyst was larger than SO~(2-)_4/TiO_2.The sample containing Al contained more sulphur than samples without Al which indicated Al could stabilize S on catalyst surface and reduced its loss at high calcinations temperature.Both the strength and acid amount increased with the addition of 23.1%(mole fraction)Al.The catalyst containing 23.1% Al(mole fraction)and being calcined at 400℃ showed best catalytic activity.The conversion of the pyromellitic dianhydride was up to 98.2% after 2h reaction.