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The adsorption/desorption of ethanol on CsxH3-xPW12O40 by TG/DTG-DTA analysis

O. VERDES1,* , L. AVRAM1, A. POPA1, V. SASCA1

Affiliation

  1. Institute of Chemistry Timisoara-Romanian Academy, Bd. M. Viteazu 24, 300223 Timisoara, Romania

Abstract

The adsorption/desorption of ethanol on CsxH3-xPW12O40 was studied recording the TG, DTG, DTA and T curves during experiments. The adsorption of ethanol at 100 oC on H3PW, Cs1H2PW, Cs2H1PW and Cs2.25H0.75PW take place exclusively on Brönsted acid sites by hydrogen bonds formation, unlike the Cs3PW where physisorption prevails. In the Cs2.5H0.5PW case there is a significant quantity of physisorbed ethanol together with hydrogen bonded ethanol. The subsequent desorption take place from Brönsted acid sites in similar way with crystallization water removal. The highest desorbed ethanol on Cs2.25H0.75PW and Cs2.5H0.5PW of 1, respectively 1.4 EtOH/H+ could be a result of easier access to the Brönsted acid sites. The results of the adsorption at 300 oC show that ethanol reacts during adsorption/desorption steps with formation of strongly adsorbed species, reduction of the solids and carbonaceous deposit formation. The deactivation as result of the strongly adsorbed species and the carbonaceous deposit is discussed..

Keywords

Tungstophosphoric acid, Tungstophosphates of Cs, Adsorption-desorption of ethanol.

Submitted at: Feb. 24, 2012
Accepted at: June 6, 2012

Citation

O. VERDES, L. AVRAM, A. POPA, V. SASCA, The adsorption/desorption of ethanol on CsxH3-xPW12O40 by TG/DTG-DTA analysis, Journal of Optoelectronics and Advanced Materials Vol. 14, Iss. 5-6, pp. 537-543 (2012)