纯化学试剂合成的介孔分子筛, 由于水热稳定性较差、成本较高, 因而限制了其在催化、吸附等工业领域的大规模应用. 以廉价且高结晶度的天然矿物蒙脱石为原料, 选用硅酸钠和工业白炭黑作为补充硅源, 成功地合成了具有优异水热稳定性的介孔蒙脱石. 使用XRD、FTIR、TEM、N2脱吸附等温线等手段对介孔蒙脱石的结构进行了分析, 并讨论了高能球磨、搅拌时间、补充硅源种类等因素对样品结构及水热稳定性的影响. 实验结果表明, 以硅酸钠-纳米白炭黑复合无机硅源制备的介孔粘土具有十分优异的稳定性, 样品水热反应10d后依然保持着规则的介孔结构, 且比表面积仍在580m2/g以上.
Poor stabilities of synthesized mesoporous sieves inhibit their applications. In present work nanosized high crystalline mineral, natural montmorillonite, was introduced into the synthetic system in order to improve the stability of mesoporous sieve. Two additional siliceous sources, Na2SiO3 and nano-sized white silica, were employed to widen the gallery space of montmorillonite into nano-scale. The resultant mesoporous montmorillonite was charactered by XRD, FTIR, TEM and N2 adsorption-desorption isotherms. Moreover, the influences of milling conditions, stirring time, and type of siliceous sources on the porous structures and the hydrothermal stabilities of mesoporous montmorillonite were also discussed. The results show that intensive milling of raw materials is necessary to achieve longrange ordered mesopores in the structure. Furthermore, the multi siliceous sources make significant improvements on the hydrothermal stabilities of the samples, due to the cooperation effects between the Na2SiO3, white silica, and montmorillonite sheets. The highest hydrothermal stability exists in the sample synthesized from multi siliceous sources, whose original specific surface area is up to 772m2/g. After hydrothermal treatment for 10d, the sample keeps the long-range ordered mesoporous structure with specific surface area above 580m2/g.
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