73 Synthesis, characterization and catalytic evaluation of zirconia-pillared bentonite for 1, 3-dioxalane synthesis a a,b S. Mnasri and N. Frini-Srasra a Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National des Recherches en Sciences des Matériaux, Technopole Borj Cédria, BP 95-2050 Hammam lif, Tunisia b Départements de Chimie, Faculté des Sciences de Tunis, 1060 Tunis, Tunisia e-mail: email@example.com ; firstname.lastname@example.org The aim of this work is to study the solids obtained by pillaring Tunisian bentonite with zirconium polycations from the hydrolysis of zirconium tetrachloride. For comparative purposes, the pillaring of Wyoming montmorillonite, a reference clay, is also studied. Variations in the dialysis number, concentration of Zr solution, pH, temperature in the synthesis procedure as well as the pillaring method, affect the structure and properties of the pillared clay obtained. It has been verified that the structure of the pillared clays strongly depends on the method of preparation and the pH Zr solution in some cases, well ordered pillared clays (with basal spacings between 15 and 18.2A) have been obtained, while in several others noncrystalline solids yielded. Delamination of the clays seems to take place both when the intercalation solutions obtained from zirconium tetrachloride have pH > 2.8 and 4+ when they are subjected to a reflux treatment. Best results were obtained at pH = 2.8 [Zr ] = 0.1M, at room temperature, and when using five dialysis, the direct method. The specific total surface area 2 -1 3 -1 and micropore volume of the solids have reached the values up to 200 m g and 0.06 cm g , respectively. Potentiometric titration and mass titration data suggest that pillared materials produce a shift of the point zero charge toward the point zero charge of the zirconium oxide. The amount of ZrO2 fixed have varied between 6 and 30% of the weight of the pillared samples. The activity of the zirconium pillared clay for 1,3-dioxolane synthesis has been investigated. The method of intercalation has been found to be the most suitable for this reaction. Keywords: Zr-oligomer; pillared clay; point of zero charge; 1,3-dioxolane; acetalization. УДК 621.762 INTRODUCTION Pillared interlayered clays (PILCs) include a new family of clays based on two-dimensional materials, and are used in adsorption and catalysis. Pillaring of clay with inorganic polycation results in producing thermally stable rigid cross linked materials with a large surface area, a certain porous texture and acidity. The properties of pillared clays depend upon several factors such as the preparation conditions (mainly pH and temperature) of the polycations, the method of intercalation, washing and drying steps. Among the cations utilized for pillaring, one of the most extensively used up to date is a polynuclear hydroxy zirconium complex whose structure is 2+ [Zr4(OH)14 (H2O)10] [1, 2]. The most commonly studied is the zirconium intercalated clay using ZrOCl2, 8H2O as a precursor [1–6]. Several works using zirconium acetate [7–10] are included in the literature list, but up to now, only one paper describing the pillaring with zirconium oligomers using ZrCl4 as a source of zirconium species has been published , to the best of the authors’ knowledge. The aim of the present work is two-fold: first, to study the solids obtained by pillaring Tunisian bentonite with zirconium polycations using ZrCl4 as a precursor. In other words, under investigation are the effects of the initial concentration of ZrCl4, the pH of the pillaring solution, its temperature, washing and the pillaring method applied on the structural and textural properties of Zr pillared Tunisian bentonite. Then, the application of the pillared bentonite as a catalyst in the synthesis of 1,3-dioxalane using acetone and et-hylene glycol is also investigated. For comparative purposes, the pillaring of Wyoming montmorillonite, a reference clay, is also studied. In recent years, considerable attention has been paid to the synthesis of 1,3-dioxalane. Thanks to its properties (having no unpleasant odor, being miscible in water and the majority of organic solvent, not toxic), this molecule is used as a reagent mainly for the protection of the carbonyl group or solvent in several applications: in organic chemistry [12, 13], in polymer , pharmaceutical [15–17] and biological [18, 19] industries. The synthesis of 1, 3-dioxolane is generally catalysed by homogeneous acid catalysts such as Rhodium (II) acetate , p-toluenesulfonic acid , tin (II) chloride  and manganese (III) acetate . In addition, it is prepared in the presence of a solvent like acetone [22, 24], or CHCl2, ACOH, MeCN, Me2CO, MeOH, CHCl3 . Unfortunately, these catalysts cause corrosion and are not environmentally friendly. On the contrary heterogeneous catalysts based on pillared clays have many advantages. They are noncorrosive and environmentally friendly. Their re- _____________________________________________________________________________________ Mnasri S., Frini-Srasra N., Электронная обработка материалов, 2013, 49(4), 73–84.