固体超强酸SO_4^(2-)/SnO_2-Al_2O_3的红外光谱研究

FTIR spectra of SO_4^(2-)/SnO_2-Al_2O_3 solid superacid

以四氯化锡、硫酸铝为原料,氨水为沉淀剂,采用共沉淀法制得新型固体超强酸SO42-/SnO2-A l2O3。采用FT-IR技术考察了金属元素摩尔比、焙烧温度、浸渍液以及掺杂稀土氧化物对该固体超强酸结构和性能的影响。FT-IR结果表明在该固体超强酸中,锡和硫酸根是以螯合和桥式两种方式配位结合,其中起催化活化作用的主要是和硫酸根以螯合双齿结合的锡;和SO42-/ZrO2型超强酸相比,SO42-/SnO2-A l2O3超强酸的硫酸根FT-IR特征吸收峰发生蓝移,显示出更强的酸性。锡铝摩尔比为9∶1、焙烧温度为773K、焙烧时间为3h时,制得的SO42-/SnO2-A l2O3样品对酯化反应的催化性能最好。

New solid superacids SO4^2-/SnO2-Al2O3 were prepared by coprecipitation method. The effects of metal ratio , calcination temperature and soakage liquids on the superacids structure and performance were also probed by FT - IR. The FT - IR results showed that in these new solid superacids SO4^2-/SnO2-Al2O3 ,the SO4^2- is combined with Sn atom by chelate and bridge bonds,in which the SO4^2- combined by chelate bonds is the main catalytic center. Compared with the FT - IR adsorption peak of SO4^2-/SnO2, the peak of SO4^2-/SnO2-Al2O3 shows blue - shift,which means the higher super acidity than that of SO4^2-/SnO2. When the metal mole ratio is 9：1 ,calcinations temperature is 773K and the calcinations time is 3h,the solid superacids SO4^2-/SnO2-Al2O3 shows the best catalysis for esterification.