Synthesis and characterization by co-precipitation under an inert atmosphere of lamellar Fe/Al double hydroxides and comparison with samples co-precipitated under an ambient atmosphere

• Published in: Journal of solid state chemistry 2023-01, Vol.317, p.123665, Article 123665
• Main Authors: Reguig, Mokhtaria, Bettahar, Nourredine, Belkhadem, Fatiha, de Ménorval, Louis-Charles
• Format: Article
• Language: English
• Subjects: BET method; BJH; Co-precipitation; Double lamellar hydroxide; Fractal analysis; Life Sciences; NLDFT
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2022.123665

Aluminum-iron layered double hydroxides were prepared by low saturation co-precipitation under ambient atmosphere and under nitrogen using various molar ratios. These materials were characterized using different analysis techniques such as X-ray diffraction, differential thermal analysis, thermogravimetric analysis, Fourier transform infrared and Nitrogen gas adsorption-desorption at the temperature −196 ​°C (BET, BJH, NLDFT). The synthesis of these materials in ambient air always gives rise to the appearance of impurities for all the molar ratios used. However, under nitrogen, the impurities start appearing as of the molar ratio equal to 3. It is worth indicating that the atmosphere used and the amount of iron added both have an impact on the formation of impurities. Four methods were used to study the textural parameters of the materials prepared under ambient conditions. The results obtained showed that the synthesized compounds are microporous, and the pore size does not exceed 2 ​nm. It was therefore concluded that the materials prepared under nitrogen atmosphere are of mesoporous-type. [Display omitted] •The oxidation of ferrous iron to ferric iron makes the synthesis of aluminum and iron type hydrotalcites very difficult.•The materials synthesized by ambient atmosphere gave microporous compounds in the presence of impurity.•The preparation of iron-based hydrotalcites should not exceed the molar ratio 2.•The BJH method underestimates the pore size by a deviation of 25% compared to the NDFT method.