磁性碳基固体酸Fe₃O₄/C-SO₃H制备及结构表征

Preparation and Structural Character-ization of Fe₃O₄/C-SO₃H Magnetic Carbon-Based Solid Acid

摘要: 以氯化亚铁、三氯化铁和氨水为原料制备Fe₃O₄，考察了分散剂种类、用量、分散方式，超声功率、反应时间和反应温度等因素对Fe₃O₄分散性的影响。以自制Fe₃O₄、可溶性淀粉和对甲苯磺酸为原料，采用一步法制得新型磁性碳基固体酸催化剂Fe₃O₄/C-SO₃H。以辛基葡萄糖苷合成反应为探针，考察m(Fe₃O₄):m(可溶性淀粉)、m(Fe₃O₄):m(对甲苯磺酸)、焙烧温度和焙烧时间对于催化剂活性的影响。并利用FT-IR、XRD、TG、SEM和VSM等表征手段对催化剂的结构进行分析。实验结果表明，十二烷基硫酸钠作为表面活性剂，用量为n(氯化亚铁):n(十二烷基硫酸钠) = 1:0.4，采用机械搅拌和超声波相结合的混合分散方式，超声功率为50 W，反应时间为1.5 h，反应温度为70℃的条件下所制备的Fe₃O₄分散性最好，其分散指数为0.209。在m(Fe₃O₄):m(可溶性淀粉):m(对甲苯磺酸) = 1:6:2.5、焙烧温度400℃、焙烧时间5 h的条件下得到的催化剂活性最佳，催化剂酸含量为0.91 mmol/g，在140℃下反应4 h葡萄糖的转化率可达到95.4%。结构分析表明，催化剂为无定形颗粒物，具备良好的热稳定性能和磁学性能。

Abstract: Fe₃O₄ was prepared from ferrous chloride, ferric chloride and ammonia. The effects of dispersant type, dosage, dispersion mode, ultrasonic power, reaction time and reaction temperature on the dispersion of Fe₃O₄ were investigated. A new magnetic carbon based solid acid catalyst Fe₃O₄/C-SO₃H was prepared by one-step method with self-made Fe₃O₄, soluble starch and p-toluenesulfonic acid as raw materials. The synthesis of octyl glucoside was a probe reaction. The effects of m (Fe₃O₄): m (soluble starch), m (Fe₃O₄): m (p-toluenesulfonic acid), calcination temperature and calcination time on the activity of the catalyst were studied. The structure of the catalyst was analyzed by FT-IR, XRD, TG, SEM and VSM. The experimental results show that the dispersion of Fe₃O₄ is the best when sodium dodecyl sulfate is used as surfactant, the dosage is n (ferrous chloride):n (sodium dodecyl sulfate) = 1:0.4, the mixed dispersion mode of mechanical stirring and ultrasonic is adopted, the ultrasonic power is 50 W, the reaction time is 1.5 h, and the reaction temperature is 70˚C, and the dispersion index is 0.209. Under the conditions of m (Fe₃O₄):m (soluble starch):m (p-toluenesulfonic acid) = 1:6:2.5, calcination temperature 400˚C and calcination time 5 h, the activity of the catalyst is the best, the acid content of the catalyst is 0.91 mmol/g, and the conversion of glucose can reach 95.4% at 140˚C for 4 h. The structure analysis shows that the catalyst is amorphous particles and has good thermal stability and magnetic properties.