Delgado José A, Uguina María A, Agueda Vicente I, García-Sanz Alicia
Department of Chemical Engineering, Universidad Complutense de Madrid, 28040, Madrid, Spain.
Langmuir. 2008 Jun 17;24(12):6107-15. doi: 10.1021/la7037894. Epub 2008 May 17.
ETS-4 is a titanium silicate developed by Engelhard Corporation, which possesses a small pore network, the size of which can be reduced by heat treatment to improve its kinetic selectivity in nitrogen/methane separation. Most of the reported studies about ETS-4 employ crystals synthesized with conventional heating. Furthermore, information available on the adsorption properties of ETS-4, especially the diffusion properties, is scarce. In this work, Na-ETS-4 crystals have been synthesized by microwave heating and have been exchanged with strontium to obtain Sr-ETS-4 using also microwave heating. This method for obtaining the strontium form of ETS-4 has not been reported before. Both materials have been dehydrated to reduce their pore size. The adsorption and diffusion parameters of nitrogen and methane on these materials, which have not been measured for microwave-synthesized ETS-4 up to the present date, have been estimated by modeling the desorption breakthrough curves of both gases using a fixed bed of ETS-4 crystals. The kinetic selectivity of nitrogen over methane at 298 K of microwave-synthesized Sr-ETS-4 is 26. This value is higher than the maxima reported in the literature for this material.
ETS - 4是恩格尔哈德公司研发的一种钛硅酸盐，它具有小孔径网络，通过热处理可减小其孔径大小，从而提高其在氮气/甲烷分离中的动力学选择性。大多数关于ETS - 4的已报道研究都采用传统加热合成的晶体。此外，关于ETS - 4吸附性能的信息，尤其是扩散性能，非常稀少。在这项工作中，通过微波加热合成了Na - ETS - 4晶体，并同样使用微波加热与锶进行交换以获得Sr - ETS - 4。此前尚未报道过这种获得ETS - 4锶形式的方法。两种材料都已脱水以减小其孔径。通过使用ETS - 4晶体固定床对两种气体的解吸穿透曲线进行建模，估算了氮气和甲烷在这些材料上的吸附和扩散参数，到目前为止，微波合成的ETS - 4的这些参数尚未被测量。微波合成的Sr - ETS - 4在298 K时氮气对甲烷的动力学选择性为26。该值高于该材料在文献中报道的最大值。
