Evaluation of ZSM-5 as a catalyst for glycerol pyrolysis by thermogravimetry Margarida L. Castello ´ • Jo Dweck • Donato A. G. Aranda Received: 15 July 2014 / Accepted: 18 December 2014 / Published online: 10 February 2015 Ó Akade ´miai Kiado ´, Budapest, Hungary 2015 Abstract ZSM-5 is a zeolite that has been used for decades in catalytic cracking processes, especially in the Brazilian oil industry. This paper investigates thermal analysis of glycerol pyrolysis by means of Kissinger and Ozawa–Flynn–Wall methods and shows activation energy for the reaction. For the experiments, the authors used pure glycerol and a commercial NR4-ZSM-5, which was heated up to 500 °C in order to activate its Bro ¨nsted acid sites. In this paper, the authors show, by quantitative thermogravi- metry and free kinetic method study, that ZSM-5 can be used as a catalyst for the pyrolysis of glycerol, even at temperatures below 250 °C. Keywords Glycerol Á ZSM-5 Á Pyrolysis Á TG and DTG Introduction In the previous work [1], the authors have reported the thermal behavior of glycerol when submitted to heating up to 600 °C, studied by thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA), performing isothermal and dynamic analyses in nitrogen flow. By comparing the activation energies (E a ) calculated by Kissinger [2] and by Ozawa–Flynn–Wall [3] free kinetic methods, it was possible to conclude that glycerol does not undergo simple volatilization, although this is the predominant process when the degree of con- version has not yet reached 40 % of total mass. Confir- mation of these conclusions was done by using Blazejowsky method [4], which allowed estimating the volatilization enthalpies based on Van’t Hoff’s equation. Cracking reactions require the breakage of covalent links (sigma or pi), which characterize a process with high activation energy. For the pyrolysis of molecules such as glycerol, in which links to be broken are C–C, C–H, O–H and C–O, there are already many catalysts tested success- fully, which have been employed in industrial large-scale processes. In the petroleum industry, where the links to be broken are mostly the same, the use of zeolites has become economically profitable since it has been installed in refineries in the 1940s. The ZSM-5 (Zeolite Socony Mobil 5) has some particular characteristics, such as the fact that it has peculiar pore mor- phology. This zeolite, also called ‘‘pentasil’’ due to its crys- talline structure that resembles pentagons forming a three- dimensional mosaic, has two systems of elliptical channels that intersect each other: One is rectilinear and the other is sinusoidal, through which openings of the 10MR (rings formed by eight pentagons and two hexagons) are linked [5]. Al or Si forms the vertices, and oxygen atoms link the ring- shaped chains. The crystallographic unit cell has 96 sites of Si or Al, 196 oxygen sites and a number of compensation cations dependent on the Si/Al ratio (SAR), which may vary greatly and usually is higher than 12. These are the sites (in which compensation cations impress a protonic load) which give to ZSM-5 the acidity required to break the C–C links [6]. M. L. Castello ´(&) Á J. Dweck Á D. A. G. Aranda Chemical School, Federal University of Rio de Janeiro, Bloco E of CT, Rooms E-206 e E-211, Cidade Universita ´ria, Rio de Janeiro, RJ 212949-900, Brazil e-mail: mcastello@eq.ufrj.br J. Dweck e-mail: jodweck@yahoo.com.br D. A. G. Aranda e-mail: donato@gmail.com M. L. Castello ´ Fluminense Federal Institute, Campus Macae ´, Km. 164, Amaral Peixoto Road, Imboassica, Macae ´, RJ 27925-290, Brazil 123 J Therm Anal Calorim (2015) 119:2179–2185 DOI 10.1007/s10973-014-4365-3