Co@C催化木质素衍生酚类化合物的加氢转化

Hydrogenation of lignin-derived phenolic compounds over Co@C catalysts

采用溶剂热法合成Co-MOF,然后通过一步热解法制备了Co@C催化剂。通过N2物理吸附-脱附(BET)、X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等分析手段对Co@C催化剂的结构进行了表征。探讨了Co-MOF热解温度、反应温度、初始氢压以及反应时间对Co@C催化愈创木酚加氢转化的影响。结果表明,Co-MOF和Co@C中均以介孔为主;片层结构的Co-MOF热解后变成不规则的球状,并且随着热解温度升高,Co@C的比表面积不断减小。以Co@C-600为催化剂,在反应温度180℃、初始氢压2 MPa、反应时间2 h的条件下,愈创木酚完全转化,环己醇的选择性为92.8%。Co@C催化愈创木酚加氢转化的主要反应路径为先通过脱甲氧基生成苯酚,进一步加氢生成环己醇。此外,Co@C-600对苯酚、对甲氧基苯酚和4-甲基愈创木酚等其他衍生酚单体也具有较好的催化活性。

Co-MOF was firstly prepared by solvothermal method,and then Co@C catalyst was prepared by onestep pyrolysis method from Co-MOF.The structure of Co@C catalyst was characterized by N2 physical adsorptiondesorption(BET),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Effects of Co-MOF pyrolysis temperature,reaction temperature,initial hydrogen pressure and reaction time on catalytic hydrogenation of guaiacol were investigated.The results show that both Co-MOF and Co@C are dominated by mesoporous.After pyrolysis,lamellar structure of Co-MOF changes into irregular sphericity.As raising pyrolysis temperature,specific surface area of Co@C decreases continuously.Under the conditions of reaction temperature 180℃,initial hydrogen pressure 2 MPa and reaction time 2 h,the guaiacol was completely transformed and selectivity of cyclohexanol was 92.8% using Co@C-600 as catalyst.The main reaction pathway of guaiacol hydrogenation catalyzed by Co@C is that guaiacol firstly forms phenol through removal of methoxyl group,and further is hydrogenated to cyclohexanol.In addition,Co@C-600 also has good catalytic activity for other phenolic monomers derived from lignin,such as phenol,pmethoxyphenol and 4-methyl guaiacol.