Influência do lantânio sobre a porosidade e a acidez de uma Vermiculita mesoporosa e sua importância na adsorção de dióxido de carbono

Abstract

The influence of lanthanum on the porosity and acidity of mesoporous vermiculite was actually studied and analyzed and it is therefore used as a precursor material vermiculite from Paraíba, Brazil. By insertion of polyhydroxy cationic oligomer at different ratios Al / La between the layers, followed by calcination for the formation of the pillars, we obtained mesoporous vermiculite. The material was characterized by the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), Móssbauer spectroscopy, absorption spectroscopy, infrared spectroscopy (FTIR) detettnination of cation exchange capacity (CEC) of photometrically flame, complexometric titration and conventional, analysis of textural characteristics by BET. The verification of the crystalline phases and the efficiency of obtaining the mesoporous vermiculite was performed by the d002 peak shift to smaller 20 angles, by means of XRD measurements, using the powder method. The chemical analysis of samples of natural and modified vermiculite with aluminum oligomer was obtained by XRF, where there was a considerable loss of iron, possibly resulting from chemical processes employed, being the magnesium content found significant. The increased acidity of Brdnsted and Lewis was evidenced by FTIR bands characteristic of each site, with doping with Lanthanum aluminum oligomer, and the sample Al-2La-PILV-1 at more acidic. The BET analysis showed that the incorporation of aluminum oligomer caused increased surface area, while the lanthanum doping resulted in mesoporous materials with larger pore size compared with the pillared lanthanum without due to the larger ionic radius of lanthanum (106 pm) compared with aluminum (53,5 pm). The sample of vermiculite modified with All; oligomers showed higher adsorption capacity for CO2 (2.32 mmol g-1).