Surfactantless synthesis and textural properties of self-assembled mesoporous SnO₂

Abstract

Ordered surfactantless self-assembled, mesoporous SnO(2) adsorbents, consisting of tubular voids of nanometric sizes, are prepared by the sol-gel processing of tin (IV) tetra-tert-amyloxide, Sn(OAm(t))(4), whose molecules have been previously chelated with acetylacetone in the absence of water, to modulate their reactivity and to promote an incipient self-assembling of -O-Sn-O oligomeric species; ultimately, the necessary amount of water to induce the hydrolysis-condensation reactions is added to this aged sol, then producing tubular pore templates within the SnO(2) xerogel network. A collection of mesoporous SnO(2) xerogels of assorted structural properties has been obtained after calcination in air of precursory gels proceeding from an aged mixture of Sn(OAm(t))(4) and acetylacetone at temperatures in the range 200-1000 degrees C. N(2) sorption isotherms measured on these SnO(2) solids evidence mesoporous structures of diverse textural characteristics (i.e. pore widths of 3-50 nm and surface areas of 10-140 m(2) g(-1)) in which voids virtually behave as if they are independent cylindrical pores during capillary condensation and evaporation.