The conversion of n-heptanes into aromatic hydrocarbons benzene, toluene and xylenes (BTX), by the chromatographic pulse method in the temperature range of 673 - 823K was performed over the HZSM-5 and Ag-HZSM-5 zeolites modified by ion exchange with AgNO3 aqueous solutions. The catalysts, HZSM-5 (SiO2/Al2O3 = 33.9), and Ag-HZSM-5 (Ag1-HZSM-5 wt. % Ag1.02, Ag2-HZSM-5 wt. % Ag 1.62; and Ag3-HZSM-5 wt. % Ag 2.05 having different acid strength distribution exhibit a conversion and a yield of aromatics depending on temperature and metal content. The yield of aromatic hydrocarbons BTX appreciably increased by incorporating silver cations Ag+ into HZSM-5.

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To study the respective deformation modes of the Al and CuAl2 lamellae as well as the interface properties (phase boundaries, lamellar faults) in lamellar eutectic monograins, in situ creep experiments are performed in a high voltage electron microscope between 270 and 350 °C. They are completed by conventional observations of crept samples. At 300 °C a transition occurs: at lower temperatures the CuAl2 phase is brittel by lack of dislocations while above 300 °C dislocation multiplication and movement are possible, involving high friction forces. Outlines for two corresponding deformation models are proposed, involving the observed interface sliding, dislocation sources in volume or at the phase boundaries, shearing of the Al lamellae, and a heterogeneous deformation. These models are discussed in terms of the activation parameters measured in macroscopic creep tests presented in another article.

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