Cu hydrotalcite-like compounds: Morphological, structural and microstructural properties

Copper containing mixed oxides are widely employed as catalysts for the synthesis of methanol, higher alcohol, hydrocarbons from syngas at low temperature and pressure, and for NiO_x reduction. In this work, a series of Mg-Al-Cu, as hydrotalcite-like compounds (Cu-HTlcs) precursors of mixed oxides were synthesized by direct coprecipitation. The effect of pH, Cu content and mechanical milling on the structure and texture of these materials was investigated. The obtained materials were characterized by X-ray diffraction, differential scanning calorimetry, scanning and transmission electron microscopy and BET surface area measurements. The results showed that the materials were nanocrystalline powders. The Cu-HTlcs has a hexagonal unit cell. The a and c parameters increased as a function of the Cu content in both milled and non-milled samples. Crystallite size also increased with Cu content in both cases and smaller for non-milled samples. In contrast, microstrain values were greater for milled samples. BET area decreased with Cu content and showed that materials synthesized were mesoporous type. Mechanical milling did not destroy the morphology of the samples.