Compensation Effects In The Non-isothermal Pyrolysis Of Wood

Abstract

A considerable variation exists in the kinetics constants that were derived using Arrhenius equation in the study of the reaction kinetics for wood pyrolysis. It is of interest to evaluate whether compensation behaviours that usually associate with a series of related reactions might have contributed to the observed variations in the nonisothermal pyrolysis kinetics. The study of the compensation effects was intended to seek a logical explanation for the observed variations of the apparently large and differed values of activation energy and pre-exponential factors. Statistical regression analyses were performed to correlate the Arrhenius parameters derived from the non-isothermal Thermogravimetry Analysis (TGA) data. To gain an insight on the competing reactions so as to expound the varied kinetic data, these transition kinetics were also analyzed for exothermic transition using Differential Scanning Calorimetry (DSC) for heat of pyrolysis. This study showed that compensation effect existed, but found that the enthalpy of transition held a stronger proposition on the transition kinetics. KEYWORDS

Mathematical Modelling of Pyrolysis of Hardwood (Acacia)

“…The kinetic constants evaluated for different size of chips is shown in Table 3. The estimated value of activation energy is compared with the different species of wood and it is within permissible range of variation [18,19,20]. The activation energy for hardwood (acacia) varies from 73.5 kJ mol -1 to 88.48 kJ mol -1 ; whereas the frequency factor, 1.02 x 10 4 min -1 to 1.27 x 10 4 min -1 .…”

Mathematical Modelling of Pyrolysis of Hardwood (Acacia)

“…The kinetic constants evaluated for different chip sizes are shown in Table 3. The estimated value of activation energy is compared with the different species of wood and it is within permissible range of variation (Lim and Chew, 2005). The activation energy for hardwood (acacia) varies from 73.5 to 88.48 kJ•mol -1 , whereas the frequency factor varies from 1.02 × 10 4 to 1.27 × 10 4 min -1 .…”

“…The decrease in the convection resistance must be higher than the increase in the conduction resistance for better correlation between the experimental and the mathematical model. Source*: Lim and Chew, 2005;Blasi, 1993;Dhaundiyal and Singh 2019 References…”

Parameter Kinetik Char Hasil Pirolisis Serbuk Kayu Mahoni (Switenia Macrophylla) dengan Variasi Heating Rate dan 1 Temperatur

“…Variasi temperatur dan heating rate berpengaruh terhadap nilai Ea (Energi aktivasi) dan A (pre-exponensial factor) pada kayu Balau, Durian, Kapur dan Meranti [3]. Dengan variasi temperatur dan heating rate sangat berpengaruh terhadap nilai Ea dan A pada kayu poplar baik dengan model Kissinger, Kissinger-Akahira-Sunose (KAS), dan Flynn-Wall-Ozawa (FWO) [4] Selain itu laju kenaikan pemanasan pada proses pirolisis mempengaruhi produk hasil pirolisis, jika laju pemanasan (heating rate) rendah atau lambat maka produk yang dihasilkan akan cenderung lebih ke arang aktif / char, sedangkan jika laju pemanasan (heating rate) tinggi atau cepat maka produk yang dihasilkan berupa minyak pirolisis / tar [7].…”