酸的种类和浓度对有序介孔二氧化硅形貌和孔结构的影响

Influences of Sort and Concentration of Acid on Morphology and Pore Structure of Ordered Mesoporous Silica

以三嵌段共聚物聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO)为模板剂,正硅酸乙酯为无机硅源,HCl、HNO3、H2SO4及H3PO4四种酸为酸性介质,采用水热法合成有序介孔分子筛SBA-15。通过扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、N2吸附-脱附等手段对产物的形貌和结构进行分析。结果表明:控制合成母液中H+浓度在一定范围时,HCl、HNO3、H2SO4、H3PO4四种介质中合成出的产品分别为"麦穗"状、"铜钱"状、长程连续"糖块"状和高度分散"糖块"状;在酸种类相同条件下,酸浓度对孔道的大小、微孔含量、孔壁厚度等孔道结构参数有一定影响,但酸浓度对孔道的影响要远小于酸种类的影响。

Using poly（ethylene oxide）-poly（propylene oxide）-poly（ethylene oxide） triblock copolymer as a template and tetraethyl orthosilicate as a silica source, ordered mesoporous silica SBA-15 molecular sieves were synthesized by the hydrothermal method in HCl, HNOa, H2 SO4 and Ha PO4 media respectively. The characteristics of the structure and morphology of the SBA-15 samples were investigated by X-ray diffraction （XRD）, scanning electron mi- croscopy （SEM）, transmission electron microscopy （TEM） and nitrogen adsorption desorption analysis. The results show that acid concentration and kinds are the key factors that have great effects on the morphology and pore structure of the SAB-15. The morphology of the products synthesized in hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid medium are ＂spike-like＂,＂coins like＂, long-range continuous ＂candy＂ shape and highly dispersed ＂sugar lump＂ respectively. Under the same sort of acid, the acid concentration has an impact on the size, pore content, pore wall thickness and other parameters of the pore structure, but the effects of acid concentration is much smaller than the sort of acid.