Kinetic study of the pyrolysis of miscanthus and its acid hydrolysis residue by thermogravimetric analysis

Abstract

The kinetic parameters of the pyrolysis of miscanthus and its acid hydrolysis residue (AHR) were determined using thermogravimetric analysis (TGA). The AHR was produced at the University of Limerick by treating miscanthus with 5 wt.% sulphuric acid at 175°C as representative of a lignocellulosic acid hydrolysis product. For the TGA experiments, 3 to 6 g of sample, milled and sieved to a particle size below 250 μm, were placed in the TGA ceramic crucible. The experiments were carried out under non-isothermal conditions heating the samples from 50 to 900°C at heating rates of 2.5, 5, 10, 17 and 25°C/min. The activation energy (E A ) of the decomposition process was determined from the TGA data by differential analysis (Friedman) and three isoconversional methods of integral analysis (Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, Vyazovkin). The activation energy ranged from 129 to 156 kJ/mol for miscanthus and from 200 to 376 kJ/mol for AHR increasing with increasing conversion. The reaction model was selected using the non-linear least squares method and the preexponential factor was calculated from the Arrhenius approximation. The results showed that the best fitting reaction model was the third order reaction for both feedstocks. The pre-exponential factor was in the range of 5.6 × 10 10 to 3.9 × 10 +13 min −1 for miscanthus and 2.1 × 10 16 to 7.7 × 10 25 min −1 for AHR.

Physicochemical characterization of miscanthus and its application in heavy metals removal from wastewaters

“…It is apparent that the pyrolysis of DM occurred in a single decomposition peak illustrating the same behavior reported by Cortes and Bridgwater [38]. These three main components of biomass in general covered, respectively, 40-60, 20-40, and 10-25 wt % of any lignocellulosic biomass and for miscanthus specifically 41, 30, and 22, respectively, with some extractives around 7 wt % on a dry basis as reported by Cortes and Bridgwater [38]. These three main components of biomass in general covered, respectively, 40-60, 20-40, and 10-25 wt % of any lignocellulosic biomass and for miscanthus specifically 41, 30, and 22, respectively, with some extractives around 7 wt % on a dry basis as reported by Cortes and Bridgwater [38].…”

“…However, a significant amount of carbon remained in the ash (21.2%), indicating that there are heavier and more stable forms of carbon within the sample [47]. From this, the percentage of carbon (42.85%) is slightly lower than that published by Kok and Ozgur [47] and Cortes and Bridgwater [38] i.e. This was supported by the SEM when using the BSED which showed a higher concentration of heavier elements present in MA than that of DM.…”

“…Elemental (C, H, and N) analysis was performed using a Perkin Elmer PE2400 CHNS/O Elemental Analyzer. Again with the TGA, % ash was obtained by heating to 5008C with a heating rate of 108C/min then heating to 5758C with 2.58C/min and holding for 10 min [38]. Proximate analysis was carried out according to the ASTM method to determine the % of moisture (ASTM D2867-95), volatile matter (ASTM D5832-95), ash content (ASTM D2866-94), char, and fixed carbon (by difference) [36,37].…”

Mathematical Models for Prediction of Water Evaporation and Thermal Degradation Kinetics of Potato Starch Nanoparticles Obtained by Nanoprecipitation

“…Several approximate methods have been proposed to resolve Equation . Friedman is an approximate method, in which, the chemistry of the decomposition process is independent of the temperature, but it depends on the rate of mass loss . In this sense, Equation can be rewritten as: …”

“…Ozawa‐Flynn‐Wall (OFW) and Kissinger‐Akahira‐Sunose (KAS) approximate methods consider the effect of temperature on the chemistry of the decomposition process . Therefore, Equation by separation of variable and integration can be rewritten as: where g ( α ), is the integral form of the conversion function …”