Activity of titania and zeolite samples dosed with triethylamine

Abstract

Certain properties of titania and the ammonium- and proton-form of Y zeolites silica/alumina = 5.2 were explored before and after treatment by triethylamine (TEA). The effect of the triethylamine upon the physical and chemical properties of both titania and the zeolite were characterized by physical and chemical adsorption methods. BET surface area data showed enhanced surface area of the TEA-treated nanotitania over the untreated nanotitania; whereas, the TEA-treated zeolite showed a considerable decrease in surface area compared to the untreated zeolite. A lower bound on the exothermic heat release from the sol–gel generated TiO2 nanoparticle-TEA interaction has been evaluated. Temperature programmed desorption (TPD) of the TEA-treated Y zeolite showed that weakly adsorbed TEA left the surface between 150 and 300 °C; strongly adsorbed TEA decomposed to ethylene and ammonia at higher temperatures. Methanol adsorption isotherms and temperature-programmed, surface reaction (TPSR) were used to understand further the Zeolite-TEA interactions and correlations were made to CO2 adsorption. XPS, IR, and Raman spectroscopies, powder XRD, and 27Al MAS-NMR spectroscopy were used characterize the changes attending the TEA adsorption. Pre-adsorbed, triethylamine decorated acid sites so as to neutralize these sites for the reaction of methanol to dimethyl ether. Carbon monoxide and formaldehyde, products of the methanol probe reaction, were observed – suggesting that basic sites are present in this treated zeolite and titania.