{"title":"A Kinetic Study of the Nonisothermal Pyrolysis of Wood","authors":"S. V. Vasilevich, A. V. Mitrofanov","doi":"10.1134/s0023158424601657","DOIUrl":null,"url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Results of a kinetic study of the pyrolysis of woody biomass (<i>Quercus robur</i>) under conditions of continuous heating to a temperature of 873 K at a constant rate of 1.25, 2.5, 5, and 10 K/min have been discussed. An integral method has been used to describe the reaction mechanism and determine the macrokinetic parameters. It has been found that, from a phenomenological point of view, the averaged woody biomass pyrolysis reaction under test conditions corresponds to a three-dimensional diffusion model (1.25 K/min), a model described by the third-order reaction equation (2.5, 5 K/min), and a one-dimensional diffusion model (10 K/min). In this case, the relative standard deviation of the conversion values calculated using this equation from the test data is <11.2%. The division of the averaged reaction into three stages (first stage is completed at a temperature of 390 K; the second, at 579 K; the third, at the completion of the conversion process) leads to agreement between the calculated degree of degradation of the studied biomass samples and the test values in a range of the degree of degradation of 0–1. Although the relative standard deviation does not exceed 3.5%, the division of the averaged reaction into stages does not exclude discrepancies in the values of the determined macrokinetic parameters. It has been shown that the choice of the model that provides the best description of the wood conversion process depends on heating rate during the tests. Owing to this dependence, the macrokinetic parameter values significantly differ from each other. Taking this fact into account, it can be concluded that the selected models and calculated macrokinetic parameters are of a formal nature and cannot be thought of as physicochemical characteristics that are universal with respect to the subject of research. Discrepancies in calculations of macrokinetic parameters that are caused by the effect of heating rate can be eliminated by studying the kinetics of conversion under isothermal conditions (at a constant temperature).</p>","PeriodicalId":682,"journal":{"name":"Kinetics and Catalysis","volume":null,"pages":null},"PeriodicalIF":1.3000,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Kinetics and Catalysis","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1134/s0023158424601657","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
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Abstract
Results of a kinetic study of the pyrolysis of woody biomass (Quercus robur) under conditions of continuous heating to a temperature of 873 K at a constant rate of 1.25, 2.5, 5, and 10 K/min have been discussed. An integral method has been used to describe the reaction mechanism and determine the macrokinetic parameters. It has been found that, from a phenomenological point of view, the averaged woody biomass pyrolysis reaction under test conditions corresponds to a three-dimensional diffusion model (1.25 K/min), a model described by the third-order reaction equation (2.5, 5 K/min), and a one-dimensional diffusion model (10 K/min). In this case, the relative standard deviation of the conversion values calculated using this equation from the test data is <11.2%. The division of the averaged reaction into three stages (first stage is completed at a temperature of 390 K; the second, at 579 K; the third, at the completion of the conversion process) leads to agreement between the calculated degree of degradation of the studied biomass samples and the test values in a range of the degree of degradation of 0–1. Although the relative standard deviation does not exceed 3.5%, the division of the averaged reaction into stages does not exclude discrepancies in the values of the determined macrokinetic parameters. It has been shown that the choice of the model that provides the best description of the wood conversion process depends on heating rate during the tests. Owing to this dependence, the macrokinetic parameter values significantly differ from each other. Taking this fact into account, it can be concluded that the selected models and calculated macrokinetic parameters are of a formal nature and cannot be thought of as physicochemical characteristics that are universal with respect to the subject of research. Discrepancies in calculations of macrokinetic parameters that are caused by the effect of heating rate can be eliminated by studying the kinetics of conversion under isothermal conditions (at a constant temperature).
期刊介绍：
Kinetics and Catalysis Russian is a periodical that publishes theoretical and experimental works on homogeneous and heterogeneous kinetics and catalysis. Other topics include the mechanism and kinetics of noncatalytic processes in gaseous, liquid, and solid phases, quantum chemical calculations in kinetics and catalysis, methods of studying catalytic processes and catalysts, the chemistry of catalysts and adsorbent surfaces, the structure and physicochemical properties of catalysts, preparation and poisoning of catalysts, macrokinetics, and computer simulations in catalysis. The journal also publishes review articles on contemporary problems in kinetics and catalysis. The journal welcomes manuscripts from all countries in the English or Russian language.
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