2026-10-14T23:39:37Z https://www.scidb.cn/oai

10.57760/sciencedb.39852 2026-06-23T00:25:35Z

2026-06-23 Multiscale mechanistic insight into torrefaction as an efficient pretreatment strategy for upgrading gasification of waste paper doi:10.57760/sciencedb.39852 en Using paper produced by Guangdong Tianzhang Information Paper Products Co., Ltd. as the research material, the waste paper was pulverized to below 80 mesh and dried at 105°C for 24 hours to achieve constant weight. The untreated material was sourced from the same batch of paper and was thoroughly crushed and homogenized. Torrefaction was then performed on the waste paper in a fixed-bed reactor . Under a nitrogen atmosphere, the waste paper was torrefied at different temperatures (200-320°C) with a constant residence time of 40 minutes. Each experimental condition was repeated in triplicate, and the reported data represent mean values from multiple measurements.The waste paper samples (both untreated and torrefied) underwent proximate analysis according to the Chinese National Standard method (GB/T 28731-2012). Elemental composition (C, H, O, N, S, and Cl) of untreated and torrefied waste paper was determined using an elemental analyzer (Vario EL, Elementar Analysensysteme GmbH, Germany). Lower heating values (LHV) were measured with an oxygen bomb calorimeter (WZR-1T-CII, Changsha Bente, China). Structural changes before and after torrefaction were characterized by Fourier transform infrared spectroscopy (FTIR) (Nicolet iS50/iN10, Thermo Fisher Scientific, USA) and solid-state nuclear magnetic resonance (NMR) spectroscopy (Ascend™ 300WB, Bruker, Germany).By characterizing gaseous and liquid phase products during torrefaction, combined with analysis of solid products, the torrefaction reaction mechanism was established. Thermogravimetric analysis was performed using a TG-MS system (TG: 209 F1 Libra, Netzsch, Germany). Approximately 10 ± 0.1 mg of sample was heated to the torrefaction temperature at 20 K/min under high-purity nitrogen carrier gas (20 mL/min), followed by isothermal holding for 40 min. Volatiles were transferred from the TGA to the mass spectrometer for real-time monitoring of evolved gases. Liquid phase products generated from the fixed-bed reactor were collected and analyzed by GC/MS (GC: 7890B-5977B, Agilent, USA; MS: SCION SQ 456-GC, Bruker, Germany). The resulting chromatograms provide chemical fingerprints of condensable torrefaction products.Studying the torrefaction kinetics of waste paper enables the calculation of kinetic parameters and provides deeper insights into its reaction mechanisms. Among these parameters, the activation energy (E) is the most critical. As torrefaction can be considered low-temperature pyrolysis, established methodologies for calculating pyrolysis kinetic parameters offer diverse analytical approaches. The Kinetics Committee of the International Confederation for Thermal Analysis and Calorimetry (ICTAC) recommends model-free methods to minimize errors arising from assumptions of reaction mechanism functions. This approach calculates activation energies at varying conversion degrees without presuming reaction mechanisms. As an isoconversional method, the model-free approach computes kinetic parameters using data from multiple heating rates. The E values derived through this method serve to validate activation energies calculated via mechanism-dependent methods. Among model-free techniques, the Kissinger-Akahira-Sunose (KAS) method is the most widely adopted.The KAS method offers high accuracy for calculating activation energy (with activation energy deviations typically less than 10%). In this experiment, three heating rates (β) were selected. For identical conversion levels (α) across these different heating rates, linear regression using the least-squares method was performed. The linear relationship between ln(β/T2) and 1/T was established, where the slope of the resulting line is equal to -Eα/R. The activation energy Eα was then calculated based on this slope.The data used for establishing the torrefaction kinetic model were obtained using a thermogravimetric analyzer (TG: 209F1-Q, Netzsch, Germany). High-purity nitrogen was employed as the carrier gas at a flow rate of 40 mL/min. Samples weighing 10 ± 0.1 mg was heated to 400℃ at heating rates of 10 K/min, 15 K/min, and 20 K/min, respectively, to obtain the corresponding thermogravimetric curves. For the construction of the torrefaction kinetic model under trace oxygen blending conditions, a 5% O2 atmosphere was introduced into the carrier gas while maintaining all other parameters unchanged.Gasification experiments were conducted using a TG-FTIR-MS system (TG: 209 F1 Libra, Netzsch, Germany; FTIR: Tensor II, Bruker, Germany; MS: 403 Aeolos QMS, Netzsch, Germany). Approximately 10 ± 0.1 mg of sample was heated to 850°C at 20 K/min under high-purity nitrogen purge gas (20 mL/min). Upon reaching 850°C, the atmosphere was immediately switched to CO2 (20 mL/min) for isothermal holding over 1 hour. Volatiles were purged from the TGA to the FTIR spectrometer and mass spectrometer for real-time analysis.The effect of torrefaction on tar formation was analyzed via Py-GC/MS (Pyrolyzer: CDS 5200, CDS Analytical, USA; GC: 7890B-5977B, Agilent, USA; MS: SCION SQ 456-GC, Bruker, Germany). Precisely 0.1 ± 0.01 mg of sample was weighed and subsequently heated to 850°C at 10 °C/ms, followed by a 120 s residence time at peak temperature. Torrefaction; Waste paper; Physicochemical properties; Reaction mechanism; Gasification reactivity Yijian Li Shengpeng Xia Junming Liang Kun Zhao Zengli Zhao Anqing Zheng PUBLIC https://creativecommons.org/licenses/by-nc-sa/4.0/ dataset http://www.doi.org/10.1016/j.jaecs.2025.100412 Science Data Bank