介孔S2O82-/SnO2固体超强酸催化合成草酸二异戊酯

摘要

以SnCl4·5H2()和聚乙二醇6000为模板剂,采用模板法合成中孔S2O82-/SnO2固体超强酸催化剂,用Hammett指示剂法、TGA-DTA、XRD、N2-吸附进行表征,以草酸与异戊醇的酯化反应为探针反应,探讨S2O82-/SnO2固体超强酸的催化活性,研究焙烧温度、酸/醇比、催化剂加入量、反应时间等对反应酯化率的影响.结果表明:介孔S2O82-/SnO2固体超强酸催化剂具有四方晶系结构,S2O82-可延迟SnO2的晶化、抑制SnO2晶粒长大,对草酸二异戊酯的合成具有良好的催化活性;在催化剂的焙烧温度为500℃、n(异戊醇):n(草酸)=3∶1、带水剂甲苯加入量为30 mL、m(催化剂):m(草酸)=7.5、反应时间为2.5 h的条件下,草酸二异戊酯收率可达到99.2%;在中国石油抚顺石化公司石油一厂催化裂化柴油中添加草酸二异戊酯后十六烷值可提高1.2～3.0个单位,而其它性质无明显变化.%A novel mesoporous S2 O8 2-/SnO2 solid superacid catalyst was prepared using SnCl4 · 5 H2 O and polyethylene glycol 6000 as organic template.The prepared catalyst was characterized by XRD, TGA-DTA and N2-adsorption.The catalytic activity of S2O82-/SnO2 solid superacid for the esterification of oxalic acid and isoamyl alcohol was studied,and the effect of catalyst calcination temperature, acid/alcohol molar ratio, catalyst dosage and reaction time on the esterification rate was investigated as well.Results indicate that the mesoporous S2O82-/SnO2 solid superacid catalyst possess tetragonal crystalline structure,and the existence of S2O82- tends to delay the crystallization of SnO2 and inhibits the growing of crystal, thus the catalyst exhibits good catalytic activity for diisopentyl oxalate synthesis.Under the conditions of a catalyst calcination temperature of 500 ℃, n(isoamyl alcohol) : n(oxalic acid)=3: 1 ,a toluene adding amount of 30 mL,m(catalyst) : m(oxalic acid)=7.5 and a reaction time of 2.5 h, the yield of diisopentyl oxalate reached 99.2％.The obtained diisopentyl oxalate was used as cetane enhancing agent and added into the FCC diesel fractions from the No.1 Refinery of CNPC Fushun Petrochemical Company, it was found that the cetane number of this diesel fuel increased 1.2-3.0 units, and without significant effect on its other properties.