In order to avoid structural changes of the catalyst

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Unformatted text preview: east locally must be taken into account. In order to avoid structural changes of the catalyst due to this effect they were calcined 100°C above the maximum reaction temperature. Secondly, because in the partial oxidation of C3H8 considerable amounts of H2O can be produced which may led to the reconstruction of the former HT structure during the catalytic tests. HT derived catalysts calcined at temperatures • ƒ& DUH PXFK PRUH UHVLVWDQW DJDLQVW WKH UHFRQVWUXFWLRQ RI WKH IRUPHU HT structure than those calcined at lower temperatures. Thirdly, because higher calcination temperatures were regarded as undesirable because of negative effects such as the loss of surface area. To investigate the structural composition of the catalysts XRD was employed and scanning electron microscopy (SEM) for studies of their morphology. As the surface area can be an important factor it was determined by BET measurements. In order to study the reduction process and to find a suitable reduction method, which is crucial in the activation of the catalysts, temperature programmed reduction (TPR) was performed. The resistance of the reduced catalysts against oxidation was studied by temperature programmed oxidation (TPOx). The Ni dispersion of the catalysts was estimated basing on TPR results as the relative amount of reducible Ni after passivation of the reduced catalysts. The dispersion of the catalysts is not only important for its activity, but has also been reported to be important for the coke resistance of the catalysts in the related steam reforming process. In order to investigate the reducibility of the Ni2+ ions in the different phases of the catalyst and as ytrtrghrhrhhrhrhhffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff 1. Introduction 48 ytrtrghrhrhhrhrhhffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff well as the influence of the substitution of Ni2+ by Mg2+ reduction combined with in-situ high tempera...
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