CaZr1-xFexO3催化热解甘蔗渣木质素制备酚类化合物

采用固相反应法制备了一系列钙钛矿型混合离子电子导体CaZr_1-xFe_xO₃(CZFO-x, x=0, 0.2, 0.4, 0.6, 0.8, 1.0). 通过X射线衍射(XRD)、 扫描电子显微镜(SEM)及X射线光电子能谱(XPS)对其晶型、 形貌和金属赋存价态进行了表征. 采用热重分析仪(TG)测试了其催化苷蔗渣木质素(BL)热解性能, 并采用固定床微型反应器对其催化热解BL制备酚类化合物性能进行了评价, 利用气相色谱/质谱(GC/MS)对BL催化热解的气相和液相产物进行分析. 研究结果表明, CZFO-x呈粒状或层状致密结构, 随着Fe掺杂量的增加, 其特征衍射峰强度增大, 且衍射峰位置向大角度偏移, 晶胞体积及晶粒尺寸减小. 固定床反应结果显示, 在CaZr_0.8Fe_0.2O₃(CZFO-0.2)催化下, BL热解液相产物收率可达23.71%, 其中酚类化合物主要包括苯酚类、 愈创木基类、 邻苯二酚类和紫丁香基类, 其选择性分别为35.19%, 6.18%, 10.68%和14.21%, 其余产物为苯类和甲氧基芳香化合物. 反应后催化剂经氧化再生后, 仍然具有较高的催化活性和结构稳定性. 对BL催化热解气体产物进行分析发现, CZFO-0.2促进了芳香烃烷基侧链的断裂, 致使气相产物组成中C_mH_n和CH₄含量增加.

Production of Phenolic Compounds from Bagasse Lignin via Catalytic Pyrolysis of CaZr1-xFexO3†

Chemical conversion is an important approach to obtain chemical products from bagasse lignin ( BL) which favors in resource and high-value utilization of lignin. A series of perovskite-type mixed ionic and electronic conductors CaZr1-xFexO3(CZF-x;x=0, 0. 2, 0. 4, 0. 8, 1. 0) were prepared via the solid state re-action method. The crystal form, morphology, metal valence state and thermal stability were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), X-ray photoelectric spectroscopy(XPS) and thermogravimetric analysis and differential thermal analysis ( TG-DTA ) . Catalytic performance for producing phenolic compounds from bagasse lignin via catalytic pyrolysis was evaluated in a fixed bed micro-reactor. The results show that the CaZr1-xFexO3 pellets after calcinations deposit randomly in the form of irregular grains of flake with compact structure. As the doping amount of Fe increases, the characteristic peaks of mixed ionic and electronic conductor shift to large angle, the cell volume of crystal and the grain size decrease. Moreover, the pyrolysis temperature of BL was significantly reduced under the action of CaZr0. 2 Fe0. 8 O3( CZFO-0. 2) . In the test of fixed bed micro-reactor, the yield of liquid product was 23. 71%. The phenolic product was mainly consisting with phenols, guaiacyl groups, catechol and syringyl groups; their selectivities were 35. 19%, 6. 18%, 10. 68% and 14. 21% respectively. The rest of liquid products were benzenes and methoxy aromatics. The deactivated catalyst was regenerated by oxidation to removing the coke coated on the surface and exhibited the high structural stability and the better catalytic activity. Due to the enhancement of breakage for aromatic alkyl side chain by CZFO-0. 2, the contents of CH4 and CmHn in BL pyrolysis gas increased.