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212. The effect of CaO on coal gasification reaction with high-temperature copper slag as catalyst.

Author

Yang, Hanqi, Dong, Xinjiang, Zuo, Zongliang, Luo, Siyi, Cheng, Zhanjun, and Wang, Junzhi

Subjects
COAL gasification, COPPER catalysts, COPPER slag, CATALYST supports, SLAG, COPPER surfaces, CHEMICAL kinetics, SYNTHESIS gas
Abstract

In order to improve the calorific value and reducibility of the syngas produced by traditional coal gasification technology, and to solve the problem of high cost of heat source in coal gasification, this paper proposes to use high-temperature copper slag as the heat carriers and catalyst for coal gasification, and CaO as the CO2 adsorbent during the coal gasification reaction. In this way, the proportion of H2 in the syngas gas can be increased, and the coal gasification reaction can be improved. In the experiment, the samples with different ratios were fully mixed, and then thermogravimetric experiment and gasification experiment were carried out. Through research, the following rules were found. The use of high-temperature copper slag as the heat source and catalyst in coal gasification can lead to a 20% increase in the final weight loss rate. Additionally, when CaO is used as the CO2 adsorbent during the coal gasification reaction, a noticeable secondary weight loss occurs at around 600°C and can reach a maximum speed of 0.19%/min. The use of the C/S/CaO = 1/1/2 ratio can result in a maximum weight loss rate of 23%. Meanwhile, the C/S/CaO = 1/2/1 group has been shown to achieve a maximum weight loss speed of 0.5%/min, and the C/S/CaO = 1/1/1 group exhibits a maximum secondary weight loss speed of 0.32%/min. The samples after gasification experiment were analyzed by SEM, CaO produced clustered iron-based and porous structure on the surface of copper slag in gasification reaction. Based on the Coats-Redfern method, kinetics of gasification reaction is obtained, and the optimum fitting function is C2, mechanism functions didn't change with the variation of C/S/CaO. The research results suggest that CaO and copper slag can both enhance the coal gasification reaction. In addition, CaO is proven to be a more affordable and accessible CO2 adsorbent compared to other alternatives. [ABSTRACT FROM AUTHOR]

Published
2023
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215. MaMachine learning-assisted construction of C=O and pyridinic N active sites in sludge-based catalysts

Author

He, Xu, Gao, Wenjie, Xu, Jinglei, Cheng, Zhanjun, Peng, Wenchao, Yan, Beibei, Chen, Guanyi, and Li, Ning

Abstract

The type and quantity of active sites on a catalyst surface determine catalytic activity. In this study, machine learning was employed to assist in the construction of C=O and pyridine N active sites using sludge waste. Reactive descriptors, including C%, N%, O%, Fe%, pyrolysis temperature, heating rate, and pyrolysis time were proposed. Decision tree, extra tree, extreme gradient boosting (XGB), automatic relevance determination, and Bayesian ridge regression models were constructed and optimized. Among these, the XGB model was demonstrated with superior accuracy for prediction of C=O sites on the catalyst surface. Additionally, an ensemble model combining extra trees and XGB was developed to predict pyridine N, with R2value as high as 0.80 and minimum root mean square error (RMSE) of 0.1386. The ensemble model demonstrated a 17% improvement in accuracy compared to individual models. The model enables high-throughput screening of construction conditions for C=O and pyridine N. The study found that a pyrolysis temperature above of 500-800°C, a heating rate of 10-20 °C/min, and a heating time of 120-200 min favor the generation of C=O active sites. For pyridine N sites, a pyrolysis temperature between 400-600 °C, a heating rate of 5-10 °C/min, and a pyrolysis time of around 150 min are optimal. Experimental validation demonstrated that both models exhibit excellent predictive performance, with prediction errors below 10% in all cases. This research provides a method to assist in the construction of C=O and pyridine N active sites, which is beneficial for guiding the design of sludge catalysts.

Published
2025
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233. Influence of temperature on formaldehyde emission parameters of solvent-based coatings.

Author

Tan, Yaoyao, Zhi, Yatao, Gao, Meiping, Cheng, Zhanjun, Yan, Beibei, Nie, Lei, Chen, Guanyi, and Hou, Li'an

Subjects
FORMALDEHYDE, TEMPERATURE effect, PARTITION coefficient (Chemistry), SURFACE coatings, VOLATILE organic compounds, TEMPERATURE, DIFFUSION coefficients
Abstract

Temperature affects the emission behavior of formaldehyde from coatings. Initial emittable concentration (C0), diffusion coefficient (Dm) and partition coefficient (K) are three key parameters for characterizing the formaldehyde emission from coatings. However, recent research concerning temperature effect on volatile organic compound (VOC) emission from coatings mainly focused on the influence on gas-phase concentration or emission rate, and few studies were conducted on the correlation between temperature and key emission factors (C0, Dm and K). In this work, formaldehyde emission from a solvent-based coating was measured at 10, 15, 20 and 25°C in a 30 L environmental chamber. From 10 to 25°C, C0 increased by 2.35-fold, and positive linear correlation was observed between ln(C0*T0.5) and 1/T. An empirical equation characterizing temperature effect on K was derived. Temperature effects on Dm were negligible. Through the obtained equations that can characterize the correlation between temperature and the key parameters, C0 and K at different temperatures from this work can be easily calculated. This study would be useful for predicting emission behavior of formaldehyde from solvent-based coatings and better understanding the influence of temperature. [ABSTRACT FROM AUTHOR]

Published
2021
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239. Comparison of Combustion Kinetics of the Biomass Hydrolysis Residue with Raw Biomass Materials

Author

Chen, Guanyi, Wang, Yalin, Liu, Fang, Yan, Beibei, Cheng, Zhanjun, and Ma, Wenchao

Abstract

The biomass hydrolysis residue (BHR) is the residue consisting of mainly lignin after the biomass-to-ethanol process. A combustion kinetic comparison of the biomass material (BM), BHR, and three main components (lignin, cellulose, and hemicellulose) is studied by thermogravimetry (TG) using the Kissinger method and Flynn–Wall–Ozawa (FWO) method under five different heating rates. The results show that the ignition temperature (Ti) and burnout temperature (Tb) of BHR are both higher than those of BM. BM burns more sufficient than BHR because it contains more fixed carbon content. The results show that the activation energy calculated by the Kissinger method for the corn cob hydrolysis residue (CCHR), corn straw hydrolysis residue (CSHR) and corn cob (CC) is 188.08, 192.76 and 205.76 kJ/mol, respectively. The results calculated by the FWO method show that, when the mass conversion (α) is small, EBHR> EBM, as α increases, Eof BM gradually exceeds that of BHR. This could explain the phenomenon why BHR ignites earlier than BM but burns out later than BM. The power law (P4 and P2) reaction models are proper to describe the experimental behavior of BHR and BM, respectively. This paper also verifies that, on the premise of an accurate measurement of the three main components in BM and BHR, the TG curves and kinetic parameters of BM and BHR can be predicted.

Published
2020
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240. Hydrogen Production via Aqueous-Phase Reforming of Ethylene Glycol over a Nickel–Iron Alloy Catalyst: Effect of Cobalt Addition

Author

Tao, Junyu, Hou, Lian, Yan, Beibei, Chen, Guanyi, Li, Wanqing, Chen, Hong, Cheng, Zhanjun, and Lin, Fawei

Abstract

Aqueous-phase reforming of ethylene glycol for hydrogen generation was investigated over Ni, Fe, NiFe, and NiFeCo catalysts. The effect of the reduction temperature of the NiFeCo alloy catalyst was studied. The NiFe alloy catalyst showed higher catalytic activity than Ni and Fe monocatalysts as a result of their respective functions. Co addition could further enhance the performance of the NiFe alloy catalyst to a much higher level, with ethylene glycol conversion of 95.13% and H2selectivity of 99.79% achieved under an optimized reduction temperature. The NiFeCo catalyst showed significant catalytic performance under reduction temperatures as low as 300 °C as a result of the formation of metallic Ni, Fe3O4, and Co species, while the highest catalytic activity was obtained under a reduction temperature of 660 °C, where almost all metal species in the NiFeCo catalyst were reduced to the metallic phase. It was suggested that Ni played a core role for ethylene glycol conversion, Fe helped to enhance the water–gas shift reaction, and Co helped to enhance ethylene glycol adsorption as well as inhibit hydrogen adsorption on the catalyst surface. Active metal oxidation and leaching seemed to be important factors that affect the stability of the NiFeCo catalyst during aqueous-phase reforming of ethylene glycol.

Published
2020
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241. Experimental and Kinetic Modeling Studies of 3-Methylfuran Pyrolysis at Low and Atmospheric Pressures

Author

Su, Huaijiang, Wang, Jinglan, Zou, Jiabiao, Xu, Qiang, Yang, Jiuzhong, Cheng, Zhanjun, and Wei, Lixia

Abstract

Studies of 3-methylfuran (MF3) pyrolysis were carried out from 848 to 1373 K in a pyrolysis tube at 30 and 760 Torr using synchrotron vacuum ultraviolet photoionization mass spectrometry. Key products and intermediates were detected and measured, including methyl, propargyl, acetylene, ethylene, propyne/allene, vinylacetylene, propene, 1,3-butadiene, 2-butyne, ketene, etc. A pyrolysis model of MF3 was constructed and validated against the experimental data. The reaction pathways of MF3 decomposition, aromatics formation, and comparison between MF3 and 2-methylfuran pyrolysis were analyzed. The pyrolysis of MF3 was mainly controlled by the H-transfer reaction at 30 Torr. The H-transfer reaction and H-abstraction reaction dominated the consumption of MF3 at 760 Torr. MF3 had similar consumption pathways and slightly lower aromatics formation tendency than those of 2-methylfuran.

Published
2020
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242. Catalytic Reforming: A Potentially Promising Method for Treating and Utilizing Wastewater from Biogas Plants

Author

Tao, Junyu, Li, Jian, Yan, Beibei, Chen, Guanyi, Cheng, Zhanjun, Li, Wanqing, Lin, Fawei, and Hou, Lian

Abstract

This study investigated catalytic reforming, which is a thermochemical process, as a pioneering method to treat biogas slurry (wastewater from biogas plants) and generate hydrogen. Experimental validation for treating biogas slurries from digested cattle manure, fish intestine, and wheat straw was performed on Ni/α-Al2O3catalyst. The results showed that the total organic carbon, total nitrogen, and PO43–ion contents in biogas slurry could be reduced by 98.69, 98.01, and 99.32%, respectively. The highest hydrogen yield was obtained in the treatment of biogas slurry from digested cattle manure at 750 °C, in which the hydrogen yield and hydrogen concentration were 13.85 Lhydrogen/LBSand 79.77 vol %, respectively. Changes in the crystalline phase and structure of the catalyst were observed during catalytic reforming of biogas slurry. Active metal oxidization and carbon deposition were likely to be important factors affecting catalytic stability. The mass flow evaluation verified the hydrogen generation potential by the catalytic reforming of biogas slurry, which was close to the methane generation capability of the upstream biogas plant. However, additional effort is required to address the high energy consumption of this method. These findings provide fundamental knowledge about the potential of applying thermochemical techniques to treat and utilize high total organic carbon-containing wastewaters.

Published
2024
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243. Experimental and Kinetic Modeling Study of 2-Methylfuran Pyrolysis at Low and Atmospheric Pressures

Author

Cheng, Zhanjun, He, Sirong, Xing, Lili, Wei, Lixia, Li, Wei, Li, Tianyu, Yan, Beibei, Ma, Wenchao, and Chen, Guanyi

Abstract

The pyrolysis of 2-methylfuran (MF) was studied from 900 to 1530 K in a flow reactor at 30 and 760 Torr. Synchrotron vacuum ultraviolet photoionization mass spectrometry and gas chromatography were used for identification and mole fraction measurements of pyrolysis products, especially free radicals and aromatics. Specific products were observed for the two main unimolecular decomposition pathways of MF, such as propargyl radical, methyl radical, 1-butyne, and carbon monoxide. A previous kinetic model of MF was updated on the basis of recent theoretical and modeling progresses, especially for the aromatic formation sub-mechanism. The updated model was validated by the new pyrolysis data. Kinetic analyses including rate of production analysis, and sensitivity analysis were used to provide insight into the pyrolysis chemistry of MF, especially the decomposition of MF and aromatic formation. The pyrolysis of MF was found with the kinetic characteristics of both furan pyrolysis and 2,5-dimethylfuran (DMF) pyrolysis. The decomposition of MF in pyrolysis is initiated by the unimolecular dissociation pathway, producing propargyl and acetyl radicals. Aromatics were observed with higher concentration levels in MF pyrolysis than those in DMF pyrolysis. The high concentration levels of precursors of aromatics, especially propargyl radical, are responsible for the enhanced aromatic formation in MF pyrolysis.

Published
2024
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249. Study of the Low Temperature Oxidation of Propane

Author

Cord, Maximilien, primary, Husson, Benoit, additional, Lizardo Huerta, Juan Carlos, additional, Herbinet, Olivier, additional, Glaude, Pierre-Alexandre, additional, Fournet, René, additional, Sirjean, Baptiste, additional, Battin-Leclerc, Frédérique, additional, Ruiz-Lopez, Manuel, additional, Wang, Zhandong, additional, Xie, Mingfeng, additional, Cheng, Zhanjun, additional, and Qi, Fei, additional

Published
2012
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