吡啶甲磺酸盐离子液体的固载化及其在聚甲醛二甲醚合成中的催化作用

Immobilization of N-(3-Sulfopropyl) pyridinium methanesulfonate ionic liquid and its catalytic performance in the synthesis of polyoxymethylene dimethyl ethers

采用键合法将吡啶甲磺酸盐离子液体负载在HZSM-5分子筛上,得到分子筛负载型离子液体催化剂,并将其用于聚甲醛二甲醚（PODEn）的合成。X射线衍射、红外光谱和N2吸附-脱附表征结果显示,吡啶甲磺酸盐离子液体较好地固载于分子筛上。用于催化合成PODEn时较适宜的反应条件为：离子液体负载量0.25 g、甲醇与三聚甲醛的物质的量比（即醇醛比）1.5、110℃、反应时间3 h,催化剂用量为总反应物质量的2.2%。缩合产物中柴油添加组分PODE3-8收率可达67.35%;与单纯离子液体或分子筛催化效果相比,PODE3-8收率得到提高。固载化离子液体易回收,可重复利用;当重复使用3次后,PODE3-8收率仍能达到45.62%。

N-（3-Sulfopropyl） pyridinium methanesulfonate ionic liquid was immobilized on HZSM-5 molecular sieves by chemical method and used as the catalyst in the synthesis of polyoxymethylene dimethyl ethers（PODEn）. X-ray diffraction,infrared spectroscopy and N2sorption results showed that the ionic liquid is well immobilized on the molecular sieves. The optimized reaction conditions for the synthesis of PODEndistributions are obtained,i.e. m（ionic liquid）/m（HZSM-5） = 0.25,n（CH3OH）/n（（CH2O）3） = 1.5,2.2% catalyst, 110 ℃ and 3 h. Under these conditions,the yield of PODE3 - 8,as the ideal additives for diesel fuel,reaches 67.35%,which is much higher than those with single ionic liquid or molecular sieve as the catalyst. The immobilized ionic liquid can be easily recycled and reused; the yield of PODE3 - 8remains up to 45. 62% after reused for three times.