ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

MgZnAl hydrotalcite-like compounds preparation by a green method: effect of zinc content

Manuel Sánchez-Cantú, Lydia M. Pérez-Díaz, Efraín Rubio-Rosas, Victor H. Abril-Sandoval, Jorge G. Merino-Aguirre, Federico M. Reyes-Cruz, and Laura Orea

Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Avenida San Claudio y 18 Sur, C.P. 72570, Puebla, México

E-mail: manuel.sanchez@correo.buap.mx

Abstract: A series of MgZnAl hydrotalcite-like compounds with different zinc content (1–25 mass % of nominal zinc content) were prepared by a simple and environmentally-friendly method. The solids were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG), nitrogen adsorption-desorption at −196°C (BET), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and CO₂ temperature-programmed desorption (CO₂-TPD). Transesterification of castor oil with methanol was selected as a probe reaction to stress the effect of zinc incorporation. From the XRD analysis of fresh samples it was demonstrated that the incorporation of zinc is feasible in the nominal range of 1–10 mass % while in the samples with higher zinc content, zinc nitrate and ZnO as secondary crystalline phases were observed. Furthermore, the analysis of samples calcined at 450°C indicated the coexistence of the ZnO and MgO crystalline phases. From the EDS and TG characterizations, the zinc percentage and thermal decomposition of the samples were determined. It was revealed that the samples exhibited the characteristic platy-like habit of hydrotalcite-like compounds. The BET analysis confirmed that the calcined samples presented an increment in their specific surface area values compared with the pristine ones. It was established that the amount of basic sites diminished with the zinc incorporation, which also affected the conversion degree of the transesterification reaction.

Keywords: MgZnAl – hydrotalcite-like compound – friendly method – characterization

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0491-9

Chemical Papers 68 (5) 638–649 (2014)