NH_2-AlKIT-1介孔分子筛的制备、表征及其催化性能

以3-氨丙基三甲氧基硅烷、十六胺为有机碱改性剂,AlKIT-1为载体,通过化学修饰的方法,制备了含—NH2基团的介孔分子筛NH2-AlKIT-1催化剂。用X粉末射线衍射(XRD)、红外光谱(FT-IR)、N2吸附-脱附和固体核磁(MAS NMR)等方法对改性前后的AlKIT-1试样进行了结构表征,并以Knoevenagel缩合反应为探针考察了试样的催化性能。结果表明,有机碱改性后试样仍很好地保持了基体AlKIT-1的介孔结构,碱性有机基团已成功镀饰在分子筛内外表面,在苯甲醛和丙二酸二乙酯的Knoevenagel反应中表现出较好的催化性能,骨架中具有B酸位的杂原子与碱性基团存在明显的协同作用。以3-氨丙基三甲氧基硅烷改性的试样,其催化活性最高,反应12h后,丙二酸二乙酯的转化率达到了80%。

SYNTHESIS, CHARACTERIZATION AND CATALYTIC PROPERTIES OF MESOPOROUS MOLECULAR SIEVES NH2-ALKLT-1

Mesoporous molecular sieves NH2-AlKlT-1 were prepared by chemical decoration using(3aminopropyl) trimethoxysilane or 1-hexadecylamine as the organic base modifier.The samples were characterized by XRD,FT-IR,N2 adsorption-desorption and MAS NMR,and studied as catalysts in the Knoevenagel reaction.The results showed that NH2-AlKlT-1 samples maintained the original mesoporous structure of the AlKIT-1,and the organic groups had successfully grafted onto the surface of AlKIT-1.NH2-AlKlT-1 exhibited higher catalytic activity than AlKIT-1 in the Knoevenagel reaction with benzaldehyde and diethyl malonate,due to the apparent synergistic effect of Al atom as Brnsted acid and —NH2 basic groups.The sample modified by(3-aminopropyl) trimethoxysilane showed the highest catalytic activity in the Knoevenagel reaction,and the conversion of diethyl malonate reached up to 80% after 12 h.