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

  • 摘要: 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。

     

    Abstract: Co-MOF was firstly prepared by solvothermal method, and then Co@C catalyst was prepared by one-step pyrolysis method from Co-MOF. The structure of Co@C catalyst was characterized by N2 physical adsorption-desorption (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, p-methoxyphenol and 4-methyl guaiacol.

     

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