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采用后合成法将磷酸固载在纯硅介孔分子筛KIT-1表面上,制备出了表面含磷酸的样品P-KIT-1.利用X射线粉末衍射(XRD),红外光谱(IR)、低温N2吸附-脱附等手段对样品结构进行了表征,用化学滴定法测定了样品的表面酸性,以对苯二酚与叔丁醇的烷基化反应为探针反应对催化剂的性能进行了评价.实验结果表明,样品P-KIT-1保持了基体分子筛KIT-1的介孔结构,由于磷酸占据了分子筛的内外表面,占据了孔道内部空间,使其比表面积、孔容和孔径都减小,但减少不大.随着磷酸负载量的增加,样品的酸量和催化活性也随之增加,当磷酸负载量为7%时催化活性为最好,且明显高于微孔ZSM-5和β沸石,说明该催化剂样品在烷基化反应中的活性除了与样品的酸量有关外还与孔径的大小有关,是大分子反应有用的固体酸催化剂.
Phosphoric acid was immobilized on the surface of pure KIT-1 mesoporous molecular sieve by post-synthesis method to prepare P-KIT-1 sample with phosphoric acid on the surface. X-ray powder diffraction (XRD), infrared spectroscopy (IR), low temperature N2 adsorption-desorption method were used to characterize the structure of the sample. The surface acidity of the sample was determined by chemical titration. The performance of the catalyst was evaluated by the alkylation of hydroquinone and t-butanol as probe reaction The experimental results show that the sample P-KIT-1 maintains the mesoporous structure of KIT-1. Since phosphoric acid occupies the inner and outer surfaces of the molecular sieve, the P-KIT-1 occupies the inner space of the pore and decreases the specific surface area, pore volume and pore size , But the decrease was not significant.With the increase of phosphoric acid loading, the acidity and catalytic activity of the sample also increased, and the catalytic activity was the best when the phosphoric acid loading was 7%, which was obviously higher than that of microporous ZSM-5 and β zeolite, indicating that the activity of the catalyst sample in the alkylation reaction in addition to the amount of the sample is also related to the size of the pore size, the solid acid catalyst useful for the reaction of macromolecules.