介孔分子筛催化裂解木质素制备芳香化合物

Preparation of Aromatic Compounds by Catalytic Pyrolysis of Lignin over Mesoporous Molecular Sieves

以离子液体[P123mim]Cl为模板剂,合成了介孔分子筛PNS-7,通过XRD、TEM、SEM和N2吸附/脱附技术对其表征,并与传统的介孔分子筛MAS-7进行对比。结果表明:合成的新型分子筛是典型的六方介孔结构,且具有长程有序性和结晶度佳、孔径分布窄、比表面积高等优点。将PNS-7和MAS-7分子筛用于催化裂解木质素反应中,通过单因素和正交试验考察了反应温度、反应时间、催化剂种类及用量对木质素催化裂解反应的影响,相较于MAS-7分子筛,PNS-7的催化性能更佳,以乙二醇为溶剂,木质素1 g、PNS-7分子筛0.1 g,在180℃下反应3 h,木质素裂解残渣率为27.6%,产物香草酸和香草醛的选择性分别为28.2%和29.6%,此外,PNS-7分子筛具有良好的重复使用性能,重复使用4次,其催化性能未见明显降低。

The mesoporous molecular sieve PNS-7 was synthesized by using ionic liquid [P123 mim]Cl as template, and characterized by XRD,TEM,SEM and N2 adsorption/desorption techniques. Compared with the traditional mesoporous molecular sieve MAS-7,the synthesized molecular sieves PNS-7 had the typical hexagonal mesoporous structure,and the advantages of long-range orderliness,good crystallinity,narrow pore size distribution and high specific surface area. The effects of catalyst type and dosage,reaction temperature,and reaction time on the reaction of lignin were investigated by single factor and orthogonal experiments using PNS-7 and MAS-7 molecular sieves as catalysts. It was found that the molecular sieves PNS-7 had an outstanding catalytic performance for the lignin pyrolysis,and the lignin cracking residue rate was 27. 6%,the selectivities of vanilla acid and vanillin were 28.2% and 29.6% under the reaction conditions of ethylene glycol as solvent,lignin 1.0 g,PNS-70.1 g,reacted temperature 180 ℃ and reaction time 3 h. In addition,the molecular sieves PNS-7 had good reusability for the lignin pyrolysis. After 4 repetitions,catalytic performance of PNS-7 was not obviously changed.