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 th e observed X-ray diffraction peaks of the loaded samples results from the difference in the scattering power (or 'scattering contrast') betw een the two building blocks (amorphous silicate wall and amorphous sor bate) 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 materi al are similar (bromoform loaded B-MCM-41). After the recalcination of the loaded B-MCM-41 materials all X-ray diffraction intensities are r ecovered to about the same level as observed for the calcined sample w hich was never used for an adsorption experiment. It is concluded that the general structure of the MCM-41 material with its regular arrange ment of the channels is maintained during all the calcination and adso rption processes. This is confirmed by transmission electron micrograp hs of B-MCM-41 which had been calcined, loaded with bromoform and calc ined again.