Preparation and Properties of Fluorinated Alumina-Pillared α-Zirconium Phosphate Materials

Abstract

A polyoxyaluminum cluster, larger than the tridecamer ion [AlO 4 Al 12 (OH) 24 (H 2 O) 12 ] 7+ , was intercalated into R-zirconium phosphate using an oligomeric solution aged at 368 K and conducting the intercalation reaction, first at reflux and then with hydrothermal treatment, in the presence of F -. Different intercalation compounds were prepared by varying the Al 3+ /phosphate ratio, but a unique single phase material with basal spacing of 21.3 Å was obtained. As revealed by chemical analysis and X-ray photoelectron spectroscopy (XPS), F -is incorporated into the intercalated oligomer where it partially substitutes OH -ions. The XPS technique was also a helpful tool to determine the Al 3+ concentration from which other Al 3+ compounds are precipitated outside of the phosphate interlayer. Thermal treatment caused a continuous and gradual interlayer contraction up to 973 K, but no evidence of layer collapse or segregation of alumina was found, at least up to 1273 K. 31 P and 27 Al solid state NMR spectroscopies were used to investigate the mechanism of interaction between the phosphate layer and the aluminum species. Because of this interaction, the 31 P signal shifts toward higher field, at ≈20 ppm, while the 27 Al NMR spectra display the characteristic signal of octahedrally coordinated Al and of a new resonance between 44.8 and 49.8 ppm, which is related to the existence of Al-O-P bonds. An increase of the relative intensity of this signal was observed upon calcination of the materials at 673 K. The presence of F -in the interlayer aluminum oxide produced an enhancement of the thermal stability and porosity of the pillared materials. Studies of thermal-programmed desorption of NH 3 , pyridine adsorption, and decomposition of isopropyl alcohol have revealed the acid nature of fluorinated alumina-pillared R-ZrP materials. The acid sites catalyze the dehydration reaction of isopropyl alcohol with a selectivity of practically 100%.

Hydrogenation and Ring-Opening of Tetralin on Ni and NiMo Supported on Alumina-Pillared α-Zirconium Phosphate Catalysts. A Thiotolerance Study

“…A porous fluorinated alumina-pillared α-zirconium phosphate, prepared as described elsewhere (33), was chosen as the support. This support has an empirical formula Zr[Al 3.39 O 1.12 (OH) 1.60 F 4.90 ]H 0.57 (PO 4 ) 2 and is hereafter called AlZrP.…”

Fluorinated Alumina Pillared α-Zirconium Phosphates as Supports for Metallic Nickel Catalysts

“…The supports chosen were two fluorinated alumina pillared α-zirconium phosphates, prepared as described elsewhere (21) AlZrP-1, respectively. Ni 2+ was incorporated into the supports using both the incipient impregnation and ionexchange methods.…”

“…Total acidity, as measured by NH 3 temperature-programmed desorption (TPD), ranges between 1.7 and 1.5 mmol NH 3 /g and pyridine adsorption data reveal that Lewis acid sites are the most abundant, having AlZrP-1 at twice the concentration of AlZrP-05. These materials are active for the dehydration of isopropyl alcohol, with activity values ranging between 11.7 and 23.7 µmol of propylene g −1 s −1 (21). The main characteristics of the supports are summarized in Table 1.…”

“…Alumina pillared layered compounds, in which aluminum oxide nanoparticles induce permanent porosity by propping apart the layers of a bidimensional host, could be, in principle, adequate candidates. In a recent work, we described the preparation and the surface properties of fluorinated alumina α-zirconium phosphate materials (21), finding that the presence of F − improved significantly the thermal stability and porosity of alumina pillared α-zirconium phosphate. It is believed that this ion impedes uncontrolled formation of Al-O-P bonds during calcination, which otherwise would lead to stuffed structures.…”

Transition Metal Sulfide Catalysts for Petroleum Upgrading – Hydrodesulfurization Reactions

“…Nickel, molybdenum and nickel-molybdenum sulfided catalysts supported on aluminapillared -zirconium phosphate ZrAl3.39O1.12(OH)1.60F4.90 H0.57(PO4)2 (Mérida et al, 1996), with different loadings of Ni and Mo are described. The catalysts were tested in the thiophene HDS reaction at 673 K, using an automatic microcatalytic flow reactor under atmospheric pressure.…”