Kinetic Analysis of the Thermal Decomposition of Lowland and High-Moor Peats
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tic Analysis of the Thermal Decomposition of Lowland and High-Moor Peats S. I. Islamovaa,*, S. S. Timofeevaa,**, A. R. Khamatgalimovb,***, and D. V. Ermolaeva,**** a
Kazan Scientific Center, Russian Academy of Sciences, Kazan, 420111 Tatarstan, Russia b Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, Kazan, 420111 Tatarstan, Russia *e-mail: [email protected] **e-mail: [email protected] ***e–mail: [email protected] ****e-mail: [email protected] Received October 11, 2019; revised October 31, 2019; accepted February 10, 2020
Abstract—The thermal decomposition of two types of peat from the Vladimir oblast of Russia in an inert atmosphere of argon was studied for the first time with the combined use of thermogravimetry, Fourier transform IR spectroscopy, and kinetic analysis. The majority of gaseous products (CO2, CO, and CH4) were released at the main stage of pyrolysis at a decomposition temperature of 150–540°C, which was accompanied by the greatest weight loss. As a result of thermal decomposition, the predominant portion of the organic matter of peat passed into a gas phase. The Ozava–Flynn–Wall integral isoconversion method and the Criado method were used to calculate the kinetic parameters of the thermal decomposition of peat and to determine the mechanism of decomposition, respectively. The activation energies of peat varied in a range of 54– 271 kJ/mol, and heat transfer occurred through three-dimensional diffusion. Keywords: peat, pyrolysis, thermogravimetric analysis, kinetics, temperature, activation energy DOI: 10.3103/S0361521920030040
Peat resources belong to slowly renewable biomass, and they are considered as promising local fuels in regions that do not have their own reserves of liquid hydrocarbons and coal or where the development of such fuel deposits is economically unfeasible [1]. The annual increase in peat in the swamps of Russia is 250 million tons at nominal moisture content. Peat and peat products are successfully used at large-scale power plants and small enterprises in the production of heat and electricity in many countries [2–6]. In this case, peat can be directly burned at power plants either independently or mixed with other fuel in boiler units. Low-grade peat raw materials can be processed to produce fuel briquettes, coke, and torreficates, and they can also undergo thermochemical conversion in the processes of pyrolysis and gasification to obtain gaseous fuel suitable for energy generation in gas turbines [7–9]. The process of peat pyrolysis is of the greatest interest for studying because it is a preliminary step in the processes of gasification and combustion, and it does not require the presence of oxygen in the reaction atmosphere in the course of thermal decomposition. Complex processes of the transformation of the organic matter
components of peat into gaseous hydrocarbons, water vapor, hydrogen, methanol, acids, ketones, ethers, coke, tar, oil sorbent, and activated carbon occur as a result of thermochemical co
