Influence of the sorbate type on the XRD peak intensities of loaded MCM-41

Nine organic sorbates of different scattering power were adsorbed into the mesopores of calcined, high quality B-MCM-41. The intensity of the observed X-ray diffraction peaks of the loaded samples results from the difference in the scattering power (or 'scattering contrast') between the two building blocks (amorphous silicate wall and amorphous sorbate) of the MCM-41 structure. In general, the intensity of the X-ray peaks decreases with decreasing 'scattering contrast' and is zero when the scattering power of the silicate wall and the pore filling material are similar (bromoform loaded B-MCM-41). After the recalcination of the loaded B-MCM-41 materials all X-ray diffraction intensities are recovered to about the same level as observed for the calcined sample which was never used for an adsorption experiment. It is concluded that the general structure of the MCM-41 material with its regular arrangement of the channels is maintained during all the calcination and adsorption processes. This is confirmed by transmission electron micrographs of B-MCM-41 which had been calcined, loaded with bromoform and calcined again.