Influence of the acid activation of pillared smectites from Amazon (Brazil) in adsorption process with butylamine Denis Lima Guerra a, * , Vanda Porpino Lemos a , Claudio Airoldi b , Roˆmulo Simo˜es Ange´lica a a UFPA – Universidade Federal do Para´ , Centro de Geocieˆncia, Cp 1611, 66075-110 Bele´m, Pa, Brazil b UNICAMP, Instituto de Quı´mica-Universidade Estadual de Campinas, Cp 6154, 13083-970 Campinas, SP, Brazil Received 26 February 2006; accepted 11 April 2006 Available online 27 April 2006 Abstract Smectite-bearing clay samples from Para state, Amazon region, Brazil, were used for pillaring process in the present study. The natural and pillared/activated matrices were characterized using XRD, FTIR, 27 Al, 29 Si MAS NMR, TGA-DTG and textural analysis using nitrogen adsorption–desorption isotherms. The aluminum pillaring solutions (Al 13 ) were analyzed by 27 Al MAS NMR. The ion of inter- calation (Keggin’s ion) was obtained through chemical reaction of AlCl 3 6H 2 O and NaOH solutions with an approximate OH/Al 2.0 molar ratio and Al(NO 3 ) 3 and NaOH solutions with an OH/Al = 1.5. The nontronite intercalation was carried out using two methods: (1) with sodium hydroxide solution that was incorporated drop by drop in the aluminum chloride solution; and (2) using aluminum nitrate, which was maintained under vigorous stirring at 25 °C, during 3 h and calcined at 450 °C (adequate temperature for calcination) and 600 °C. The pillared clays were treated with HCl (0.10, 0.30 and 0.60 mol dm 3 ). The resulting materials were submitted to adsorption process with butylamine. The results showed that the pillarization process increases the basal spacing of the natural clay from 15.60 to 18.97 A ˚ and the superficial area from 44 to 197 m 2 /g. The thermal stability of the natural clay was improved by the pillaring procedure. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Pillared clay; Al 13 ; Smectite 1. Introduction Pillared interlayered clays (PILCs) are considered to be a new generation of microporous materials, where large two-dimensional pores allow large molecules to react, although maintaining some shape selectivity catalysts for large molecule reaction [1]. These materials are prepared through charge-compensating cations after exchanging the original cation in the interlayer space of the swelling clays with different cations polymers (Al [2–4], Fe [5,6,4], Zr [5–7], Cr [5,6,8], Ti [9] and Ga [10], among others). On calcining, the inserted cations polymers yield rigid, thermally stable oxide species, named pillars, which main- tain the clay layers and prevent their collapse in high temperatures. The main objective in pillaring clays is to achieve a basal spacing as large as possible, the operation of which contrib- utes to the development of large surface area and porous volume [11–14]. The PILCs are generally prepared from smectites clays that are formed by 2:1 layer phillosilicates, where one octa- hedral sheet containing Al 3+ in an octahedral coordination lies between two tetrahedral sheets and when isomorphic substitutions take place resulting in the inorganic layer. This negative charge is balanced by Na + , Ca 2+ ,K + and Mg 2+ adsorption in interlayer position, the cations of which are easily exchangeable [11,13,15,16]. Several intercalation studies have been reported in the lit- erature. Brindley and Sempel [17] intercalated smectite with the same types of polymers described above. Basal spacing 0277-5387/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2006.04.015 * Corresponding author. Tel.: +55 09132540235. E-mail address: dlguerra@ufpa.br (D.L. Guerra). www.elsevier.com/locate/poly Polyhedron 25 (2006) 2880–2890