SUMMARY: The surface atomic structure of MgCl 2 crystalline particles and MgCl 2 -supported Ziegler catalysts was observed by means of high resolution transmission electron microscopy.Step-terrace surface structures, characteristic of the structure of the MgCl 2 crystal, are found in the observed images of MgCl 2 particles. The observation of the structure of MgCl 2 -supported Ziegler catalysts shows that the MgCl 2 crystals are severely deformed by the processes of catalyst preparation. Due to the preparation procedure used the structure of the catalyst changes from crystalline to amorphous.
High resolution transmission electron microscopy (HRTEM) was used to directly observe the distribution of crystalline regions in Ziegler catalysts prepared by mechanical plus chemical routes (internal donor; Cat‐A: ethylbenzoate, Cat‐B: dibutylphthalate, Cat‐C: none) and by an entirely chemical route (internal donor; Cat‐D: dibutylphthalate). A comparison of Cat‐A, Cat‐B, and their precursors (ground products of an original MgCl2 with a donor) indicates that MgCl2 crystals are significantly destroyed by the co‐grinding procedure regardless of the kinds of internal donor, and further destruction preferentially occurs in Cat‐B compared with that in Cat‐A. The crystalline lattice of the original MgCl2 is destroyed from the surface into the interior region in the catalysts prepared by the former method. The destruction of the crystals is found to be severe in the following order: Cat‐C ≥ Cat‐B > Cat‐A in the surface area, Cat‐C > Cat‐B > Cat‐A in the central area. On the other hand, Cat‐D shows the different distribution of crystalline regions, which are predominantly present in the near‐surface area, but absent in the central area. These results suggest that the distribution of MgCl2 crystalline regions exhibit a strong correlation with the catalyst preparation procedures and, hence, the catalyst performance.
Infrared synchrotron radiation (IR-SR) is a broad-band light source. Its brilliance is the main advantage for microspectroscopy experiments, when the limited size of the sample often prevents the use of conventional thermal radiation sources. Cultural heritage materials are delicate and valuable; therefore, nondestructive experiments are usually preferred. Nevertheless, sometimes, small pieces can be acquired in the process of preservation and conservation. These samples are analyzed by various experimental techniques and give information about the original material and current condition. In this paper, four attempts to analyze cultural heritage materials are introduced. All these experiments are performed at the microspectroscopy station of IR beamline BL43IR in SPring-8.
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