磁性MgFe2O4及其核壳催化剂制备与煤热解性能研究

采用溶胶-凝胶法制得MgFe₂O₄前体，经焙烧得到MgFe₂O₄催化剂，再经St?ber法制得核壳结构催化剂MgFe₂O₄@SiO₂和MgFe₂O₄@SiO₂@HZSM-5(MSH)，利用VSM、XRD、SEM、FT-IR、N₂物理吸附等手段研究了催化剂的磁性能和结构特征；在固定床反应器上，考察了N₂气氛下磁性催化剂对补连塔富油煤的催化热解特性及回收再生性能。结果表明：MgFe₂O₄为立方尖晶石结构，饱和磁化强度达到181.50 emu/g，具有良好热稳定性能。上述系列磁性催化剂均呈现出良好的催化活性，其中MSH催化活性最好。与非催化热解相比，MSH催化热解焦油产率提高了57.7%，焦油中脂肪烃和苯类含量增加约2倍，稠环芳烃含量下降8.6%~9.8%。采用磁选方法可有效实现催化剂回收，经700℃下焙烧处理，可实现回收催化剂的再生。SiO₂包覆有助于提高核壳结构催化剂的磁热稳定性和催化寿命。

Preparation and coal pyrolysis performance of magnetic MgFe2O4 and its core-shell catalysts

The MgFe₂O₄ precursor was prepared by the sol-gel method, the MgFe₂O₄ catalyst was obtained by calcination, and the core-shell structure catalyst MgFe₂O₄@SiO₂ and MgFe₂O₄@SiO₂@HZSM-5 (MSH) were prepared by the St?ber method. The magnetic properties and structural characteristics of the catalysts were investigated by VSM, XRD, SEM, FT-IR, and N₂ physical adsorption. In a fixed bed reactor, under an N₂ atmosphere, the magnetic catalysts were investigated for the catalytic properties and recovery and regeneration of tar-rich coal from the Bulianta (BLT). The results show that the MgFe₂O₄ has a cubic spinel structure with a saturation magnetization of 181.50 emu/g and good thermal stability. The above series of magnetic catalysts all show good catalytic activity, among which MSH has the best catalytic activity. Compared with non-catalytic pyrolysis, the tar yield of MSH catalytic pyrolysis increased by 57.7%, the content of aliphatic hydrocarbons and benzene in the tar increased by about 2 times, and the content of polycyclic aromatic hydrocarbons decreased by 8.6%—9.8%. The magnetic separation method can effectively realize the recovery of the catalyst, and regeneration of the catalyst can be realized by roasting in 700℃. The SiO₂ coating helps to improve the magnetocaloric stability and catalytic lifetime of the core-shell catalyst.