Vol.10 (2020) No. 4 ISSN: 2088-5334 Kinetic Study of Pyrolysis of Ulin Wood Residue using Thermogravimetric Analysis Aitia Mulyawati Widiyannita a , Yano Surya Pradana a , Rochim Bakti Cahyono a , Sutijan a , Tomohiro Akiyama b , Arief Budiman a,* a Chemical Engineering Department, Faculty of Engineering, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia Email: *abudiman@ugm.ac.id b Centre for Advanced Research of Energy Conversion Materials, Hokkaido University, North 13 West 8, Kita-ku, Sapporo 060 8628, Japan E-mail: takiyama@eng.hokudai.ac.jp Abstract— Biomass as a renewable and sustainable energy source is expected to solve the energy crisis problem. Ulin wood residues as a biomass source could be converted into bioenergy utilizing the pyrolysis process since its primary component is a hydrocarbon. Pyrolysis process has received many interests for bioenergy production from biomass, elevating the importance of the kinetic study of pyrolysis. The kinetic study of pyrolysis is related to the beginning stage behavior of gasification and combustion process. The kinetic mechanism of pyrolysis is analyzed using Thermogravimetry Analysis (TGA), by estimating the mass decomposition at solid-state that shows TG and DTG curve. The TG and DTG curves were analyzed to see the effect of heating rate on decomposition temperature. This experiment was performed by heating 10 mg of Ulin wood sawdust from ambient temperature to 1473 K utilizing 100 mL/min of nitrogen (N 2 ) gas as carrier gas at various heating rate: 5, 10, 20, and 50 K/min. The kinetic parameters were determined by applying the iso-conversional methods, the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods, and then compared the results with the non iso-conversional method, using Kissinger method. The average value of activation energy calculated using the KAS and FWO methods are 253.5514 and 245.2512 kJ/mol, with the average value of constant coefficient square (R 2 ) of 0.9848 and 0.9859, respectively, whereas the calculated activation energy and R 2 using the Kissinger method are 237.4478 kJ/mol and 0.8520, respectively. Keywords— ulin wood residues; pyrolysis; thermogravimetric analysis; iso-conversional method; kinetic parameters. I. INTRODUCTION Concern about the depletion of energy from fossil fuels, some researchers have found out new and renewable energy sources [1], [2]. In order to create a more sustainable society, biomass is one of the prominent renewable energy sources in the future [3]. Biomass is an organic matter formed from living species, such as wood [4], agricultural crop residues [5], animal waste [6], municipal solid waste [7], algae [8], and some kind of organic waste. Indonesian biomass from the forestry sector has the potency to be developed as a bioenergy source [9], one of which is Ulin wood. Generally, Ulin wood is used as a raw material in the furniture industry, construction material, and vessel material that producing biomass residue. The major component of this residue is a hydrocarbon which can be converted into biofuel. The conversion of biomass into bioenergy is categorized by two methods: biochemical and thermochemical conversions. Biochemical conversion generally produces ethanol as the main product of fermentation [10]. Thermochemical conversion usually can be executed by the pyrolysis and gasification process [11]. Pyrolysis is a thermal decomposition process with limited or without oxygen [12]. Slow and fast pyrolysis can categorize pyrolysis. They depend on various factors, such as heating rate, temperature, and residence time [13]. Wood, such as Ulin wood residue, is well pyrolyzed due to the high content of hydrocarbon and the small content of moisture. Moreover, biochar, as a side-product of pyrolysis, also can be transformed to be a more valuable product, such as bio- briquette [14] and catalyst support [15] since pyrolysis has received many interests for the bioenergy production from biomass so that the kinetic study of pyrolysis is useful to be investigated. Existing studies have investigated the kinetics of biomass pyrolysis. One of the considered methods is thermogravimetry analysis (TGA). This method defines the kinetics of biomass pyrolysis by weight loss due to the devolatilization process. Devolatilization is the first decomposition process in which volatile matter started to 1624