THE ACTIVE PHASE (Ni²⁺) DISTRIBUTION IN Ni/γ-Al₂O₃CATALYSTS PREPARED BY IMPREGNATION OF BIS(ETHYLENEDIAMINE)NICKEL(II) COMPLEXES

Abstract

Pore volume and wet impregnations were carried on c-Al 2 O 3 support spheres using [Ni(H 2 O) 6 ](NO 3 ) 2 and [Ni(en) 2 (H 2 O) 2 ]X 2 complexes, where en ¼ ethylenediamine and X ¼ NO À 3 , Cl À , or CH 3 COO À . The distribution of nickel on the support was studied by optical microscopy and SEM-EDX. The use of ethylenediamine complexes leads to samples with nearly uniform profiles. The distribution is dependent on interaction of complexes with alumina, changes in viscosity during drying, and crystallization volume. Redistribution during drying is minimal for the ethylenediamine complexes. The study illustrates that increase in viscosity retards the convection distribution to outward migration. Cyclohexanol decomposition was studied as a test reaction and the results demonstrate that the macrodistribution of nickel oxide phase influences the product distribution.

Oleylamine-modified impregnation method for the preparation of a highly efficient Ni/SiO2 nanocatalyst active in the partial oxidation of methane to synthesis gas

“…The first step of the wet impregnation, deposition of metal ions on the surface support is very important, and this step affects quality of the final catalyst. Various techniques have been investigated in order to modify the wet impregnation for preparation of the high dispersion catalysts, such as the addition of ammonia, ethylene diamine or ethylene glycol into the impregnation solution [20][21][22][23][24][25]. Usage of organic additives, such as polyols, sugars or polyacids and αor γ-cyclodextrin is efficient route to optimize metal dispersion over an alumina or silica support [26,27].…”

Syngas production through methane oxy‐steam reforming over a Ni/SiO 2 nanocatalyst prepared by a modified impregnation method

“…The quality of metal ions deposition on the support surfaces (the first step of wet impregnation method) can have a significant effect on the quality of the final catalyst. To decrease metal particle size during preparation of the supported metal catalyst, adding some ordinary alkylamines (such as ethylendiamine) to the impregnation solution can be effective [18][19][20][21]. These compounds act as a cover to isolate metal ions from water molecules.…”