Iranian Journal of Materials Science and Engineering

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A series of MAl₂O₄ (M=Ni, Zn, and Cu) aluminates were prepared by using impregnation method; the metal content of the products was ranged between 5wt% to 25wt%. The samples were characterized by x-ray diffraction (XRD), Brunauer Emmett Teller (BET) surface area, NH₃ temperature-programmed desorption (NH₃-TPD), and inductively coupled argon plasma (ICP).

The specific surface areas of zinc, nickel and copper aluminates were in the ranges of 47-77m²/g, 63-87m²/g and 1.6-3m²/g, respectively. The surface acidity decreased in the order of CuAl₂O₄<< NiAl₂O₄< ZnAl₂O₄<< Al₂O₃. By increasing the amount of metals in the samples, the number of acidic sites decreased, but their strength did not significantly change. Ni-aluminates have fewer acidic sites than Zn-aluminates, particularly in strong acid sites

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In this paper the chemical interaction between catalyst and support has been studied to understand the observed different growth rate of CNTs in our previous paper. Both pure MgO and Mg(NO₃)₂ . 6H₂O as sources of the MgO catalyst support and Fe₂(SO₄)₃ · xH₂O as the source of the Fe catalyst, were employed. A Fe catalyst supported on MgO has been synthesized using the wet impregnation method followed by calcination. To compare the catalyst grain size and its distribution, the sample were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and BET specific surface area (SSA) measurement and X-ray photoelectron spectroscopy (XPS). XPS technique have utilized complementary to demonstrate the existence of chemical interaction between MgO support and Fe catalyst. Results revealed that the type of precursor used to prepare the support has a significant influence on the morphology of the support and the associated distribution of the Fe catalysts. The highest yield of MgFe₂O₄ phase was obtained using a pure MgO precursor which after calcination results in a homogenous distribution of nano-sized Fe particles over the support surface