Article
Thermodynamics
Jiawen Cai, Zhaoyang Yu, Shengqiang Yang, Jingxia Tang, Zhenqian Ma, Xionggang Xie, Xincheng Hu
Summary: Pore structure and surface morphology are important factors in coal spontaneous combustion, but little research has quantitatively described them. In this study, the evolution of the surface physical structure of different metamorphic coal during low-temperature oxidation was investigated using specific surface area analyzer and atomic force microscopy. The results showed that the average pore size of coal decreased with increasing temperature, particularly for low-metamorphic coal. On the other hand, the specific surface area increased gradually with temperature, especially for lignite. The surface morphology changed from fluctuation to a flat surface with fewer high peaks as the temperature increased, and the fractal dimension also increased, indicating a more complex pore structure and surface morphology during coal oxidation, particularly for lignite. The effect of coal surface structure on oxidizability was explained by pore connectivity and oxygen adsorption on the surface during the coal oxygen compound reaction.
Article
Construction & Building Technology
Mao Jing, Guanhua Ni, Chuanjie Zhu, Zhao Li, Gang Wang, Zhenyang Wang, Qiming Huang
Summary: In this study, fly ash, nano-silica, and triethanolamine were used to optimize the pore structure of sealing materials for efficient coal mine gas extraction. The analysis showed that common sealing materials mainly contained mesopores (52.19%) and had the smallest volume of micropores (9.88%). Single doping of fly ash reduced the pore volume by 9.5%, but increased the percentage of mesopores by 1.3% and decreased the percentage of micropores by 0.9%. Co-doping with nano-silica and fly ash increased the microporous percentage by 0.77% and the peak stress by 17.43%. The synergistic effect of fly ash, nano-silica, and triethanolamine was the most effective in optimizing the pore structure. The pore volume was reduced to 0.08198 cm(3)/g, and the fractal dimensions D-1 and D-2 increased by 2.88% and 2.48%, respectively. The microscopic morphology of the material became flatter and denser, and the hydration of fly ash was more complete.
CONSTRUCTION AND BUILDING MATERIALS
(2023)
Article
Thermodynamics
Jun He, Bohao Wang, Zhongliang Lu
Summary: We characterized the pore structure of coal samples at different distances from the magma intrusion point and at different temperatures to understand the thermal effect of temperature and magma intrusion on coal seams. The results showed that heating and magma thermal effects had similar impacts on the macropore and micropore stages of coal samples. The pore volume of coal samples increased with temperature or magma intrusion in the macropore stage but decreased in the micropore stage, with the magma thermal effect being more significant. This study contributes to the selection of coal-bed methane utilization technology in magmatic rock-influenced regions.
Article
Mathematics
Lei Song, Yongsheng Gu, Lei Zhang, Xiangyu Wang
Summary: A permeability model with fractal characteristics (FCP model) for deep coal based on nuclear magnetic resonance (NMR) is established in this study. The coal samples consist mainly of micrometer and nanometer pores, with adsorption pores accounting for the largest proportion followed by percolation pores and migration pores. The FCP model shows significantly higher prediction accuracy compared to other three models, providing a fast and effective method for the evaluation of deep coal permeability.
Article
Energy & Fuels
Jiexin Lu, Chunshan Zheng, Wuche Liu, He Li, Shiliang Shi, Yi Lu, Qing Ye, Yuannan Zheng
Summary: Microwave-assisted acidification is a promising method for enhancing CBM recovery by improving pore structure and fracture connectivity in coal. It greatly increases pore volume, length, and width of fractures compared to microwave heating or acidification alone. This study demonstrates the significant potential of microwave-assisted acidification for CBM production.
Article
Energy & Fuels
Hui Kan, Yue Wang, Wen-Long Mo, Xian-Yong Wei, Hong-Yu Mi, Kong-Jun Ma, Mei-Xia Zhu, Wen-Cang Guo, Jia Guo, Jun-Min Niu, Xing Fan
Summary: Different enhancement methods were used to treat Hefeng subbituminous coal (HSBC), and the pore structure and pyrolysis performance of each sample were investigated. Results showed that the samples had abundant micropores, mesopores, and some macropores. The pore types and characteristics varied among different samples. The fractal dimensions and kinetic parameters were closely related to the pore structure. The swelling treatment could promote the formation of tar.
Article
Geosciences, Multidisciplinary
Cong Feng, Xijian Li, Enyu Xu, Hao Sui, Feng Xue, Honggao Xie
Summary: This study demonstrates the significant influence of coal pore structure on coalbed methane exploitation. The pore structure of tectonic coal is shown to be more complex compared to primary structural coal, with increased connected pores and enhanced adsorption capacity.
NATURAL RESOURCES RESEARCH
(2023)
Article
Energy & Fuels
Dan Li, Yuan Bao, Yaya Wang, Chao An, Jianing Chang
Summary: The aim of microbially-enhanced coalbed methane (MECBM) generation is to simulate the natural process of microbial methane production and increase coalbed methane production. This study investigated the changes in pore and molecular structures during the bioconversion of coal to methane. The results showed that MECBM is a process of carbon enrichment, nitrogen/sulfur fixation, and dehydrogenation/deoxygenation. Microbes modify the coal pore structure by destroying aliphatic side chains, dissociating small molecular clusters, and reducing the degree of aromaticity. This changes the coal reservoir spatial structure, resulting in the transformation of micropores to transition pores and mesopores, and increasing the average pore width and reducing the specific surface area. This process benefits the desorption and transportation of coalbed methane.
Article
Engineering, Chemical
Wendi Wang, Zhen Liu, Mingrui Zhang, He Yang
Summary: In this paper, nitrogen adsorption measurement and low-field nuclear magnetic resonance methods are used to test the structural parameters of adsorption pores of different coal samples. It is found that the complexity of the pore size distribution increases with the increase in metamorphic degree. There is a positive correlation between the fractal dimension and the maximum adsorption capacity of N-2.
Article
Energy & Fuels
Fei Gao, Ji Xia, Rui-jie Sun, Ya-fei Shan, Zhe Jia
Summary: Injecting power plant flue gas into goaf for sequestration can effectively reduce CO2 emissions and inhibit coal spontaneous combustion. The study on the chemical environment's effect on CO2 sequestration revealed that inhibitors can significantly increase coal's CO2 adsorption capacity, enhancing the sequestration capacity of flue gas in goaf. Additionally, the pore volume and specific surface area of coal increased significantly after inhibition, contributing to the increase in CO2 adsorption capacity.
Article
Thermodynamics
Bobo Song, Xiaowei Zhai, Teng Ma, Bo Wang, Le Hao, Yujie Zhou
Summary: It is crucial to understand the mechanism of disaster caused by dried water-immersed coal by studying its influence on coal pore structure. This study conducted low-temperature nitrogen adsorption experiments on eight different metamorphic bituminous coals and their dried water-immersed coals to analyze the adsorption/desorption mechanism and investigate the effects on pore shape, pore-structure parameters, and fractal dimension. The results showed that water immersion had minimal effect on the pore shape of the coal, but decreased specific surface area and adsorption capacity while increasing total pore volume and average pore diameter. It had the greatest impact on the average pore size of moderately metamorphosed coals, which could accelerate coal oxidation and worsen gas emission. The fractal results revealed that water immersion reduced the surface fractal dimension of higher and lower metamorphic coal, while it increased that of moderately metamorphic coal, with the opposite effect on the structural fractal dimension.
Article
Thermodynamics
Hewei Zhang, Jian Shen, Geoff Wang, Kexin Li, Xiaojie Fang
Summary: This paper focuses on the heat treatment study of different lithotypes of coal using a custom designed high-temperature thermal nitrogen immersion experimental setup. The findings showed that heat treatment significantly increased the roughness and structural complexity of coal particles. It also led to an increase in the number of pores with diameters >200 nm. The heat treatment temperature played a role in affecting the total pore volume, specific surface area, and pore structure fractal dimension of the coal samples. The results indicate that heat treatment has the potential to enhance connectivity and fracture, which can facilitate methane transport.
Article
Energy & Fuels
Leilei Si, Jianping Wei, Yujun Xi, Hongyang Wang, Zhihui Wen, Bo Li, Hongtu Zhang
Summary: Intrusion of formation water into coal seams reduces gas extraction efficiency. Experiments showed decreased mineral content and changed pore structure in coal due to water intrusion. Factors such as clay mineral collapse, mineral dissolution, and coal swelling play significant roles in influencing the pore structure of coal during water intrusion.
Article
Energy & Fuels
Xianfeng Liu, Longkang Wang, Xiangguo Kong, Zhengtao Ma, Baisheng Nie, Dazhao Song, Tao Yang
Summary: The gas desorption property of coal is closely related to its pore distribution. Accurately characterizing the pore structures is crucial for understanding gas flow in coal seams. In this study, nine typical coking coal samples from the Xishan coalfield in North China were analyzed qualitatively and quantitatively for their pore structure characteristics. Fractal theory was used to evaluate the irregularity of the pores and their impact on methane desorption capacity. The results showed that pore volume and pore specific surface area varied widely across the coking coals, with micropores providing a large surface area but low pore volume, while macropores contributed the most to pore volume. Fractal dimensions were also determined and showed a small fluctuation range for D-1 and a wide range for D-2. The gas desorption capacity of coking coal was positively correlated with pore volume, pore specific surface area, and average pore diameter. The change in D-2 had a significant impact on gas desorption behavior, indicating that increased irregularity of macropores hindered gas flow. This study also found that moisture content and coal matrix properties could inhibit rapid gas release. These findings provide theoretical support for gas extraction in underground coal mines.
Article
Engineering, Chemical
Yuwen Zhu, Haiyang Liu, Tianyang Wang, Yuanjie Wang, Hanqiao Liu
Summary: A series of activated carbons were prepared from Datong bituminous coal by steam activation, and the fractal dimensions of pore structures were determined using low-temperature nitrogen adsorption and the Frenkel-Halsey-Hill model. The results showed that both micro- and mesopores were fully developed during steam activation, with activation at 750°C being more conducive to the development of pore structures, especially mesopores. The surface roughness and structure complexity of the activated carbons changed during the activation process, as indicated by the variation of their surface and structure fractal dimensions.
Article
Energy & Fuels
Yingna Du, Chen Huang, Wei Jiang, Qiangwei Yan, Yongfei Li, Gang Chen
Summary: In this study, anionic surfactants modified hydrotalcite was used as a flow improver for crude oil under low-temperature conditions. The modified hydrotalcite showed a significant viscosity reduction effect on crude oil. The mechanism of the modified hydrotalcite on viscosity and pour point of crude oil was explored through characterization and analysis of the modified hydrotalcite and oil samples.
Article
Energy & Fuels
Mohammad Saeid Rostami, Mohammad Mehdi Khodaei
Summary: In this study, a hybrid structure, MIL-53(Al)@MWCNT, was synthesized by combining MIL-53(Al) particles and -COOH functionalized multi-walled carbon nanotube (MWCNT). The hybrid structure was then embedded in a polyethersulfone (PES) polymer matrix to prepare a mixed matrix membrane (MMM) for CO2/CH4 and CO2/N2 separation. The addition of MWCNTs prevented MIL-53(Al) aggregation, improved membrane mechanical properties, and enhanced gas separation efficiency.
Article
Energy & Fuels
Yunlong Li, Desheng Huang, Xiaomeng Dong, Daoyong Yang
Summary: This study develops theoretical and experimental techniques to determine the phase behavior and physical properties of DME/flue gas/water/heavy oil systems. Eight constant composition expansion (CCE) tests are conducted to obtain new experimental data. A thermodynamic model is used to accurately predict saturation pressure and swelling factors, as well as the phase boundaries of N2/heavy oil systems and DME/CO2/heavy oil systems, with high accuracy.
Article
Energy & Fuels
Morteza Afkhamipour, Ebad Seifi, Arash Esmaeili, Mohammad Shamsi, Tohid N. Borhani
Summary: Non-conventional amines are being researched worldwide to overcome the limitations of traditional amines like MEA and MDEA. Adequate process and thermodynamic models are crucial for understanding the applicability and performance of these amines in CO2 absorption, but studies on process modeling for these amines are limited. This study used rate-based modeling and Deshmukh-Mather method to model CO2 absorption by DETA solution in a packed column, validated the model with experimental data, and conducted a sensitivity analysis of mass transfer correlations. The study also compared the CO2 absorption efficiency of DETA solution with an ionic solvent [bmim]-[PF6] and highlighted the importance of finding optimum operational parameters for maximum absorption efficiency.
Article
Energy & Fuels
Arastoo Abdi, Mohamad Awarke, M. Reza Malayeri, Masoud Riazi
Summary: The utilization of smart water in EOR operations has gained attention, but more research is needed to understand the complex mechanisms involved. This study investigated the interfacial tension between smart water and crude oil, considering factors such as salt, pH, asphaltene type, and aged smart water. The results revealed that the hydration of ions in smart water plays a key role in its efficacy, with acidic and basic asphaltene acting as intrinsic surfactants. The pH also influenced the interfacial tension, and the aged smart water's interaction with crude oil depended on asphaltene type, salt, and salinity.
Article
Energy & Fuels
Dongao Zhu, Kun Zhu, Lixian Xu, Haiyan Huang, Jing He, Wenshuai Zhu, Huaming Li, Wei Jiang
Summary: In this study, cobalt-based metal-organic frameworks (Co-based MOFs) were used as supports and co-catalysts to confine the NHPI catalyst, solving the leaching issue. The NHPI@Co-MOF with carboxyl groups exhibited stronger acidity and facilitated the generation of active oxygen radicals O2•, resulting in enhanced catalytic activity. This research provides valuable insights into the selection of suitable organic linkers and broadens the research horizon of MOF hybrids in efficient oxidative desulfurization (ODS) applications.
Article
Energy & Fuels
Edwin G. Hoyos, Gloria Amo-Duodu, U. Gulsum Kiral, Laura Vargas-Estrada, Raquel Lebrero, Rail Munoz
Summary: This study investigated the impact of carbon-coated zero-valent nanoparticle concentration on photosynthetic biogas upgrading. The addition of nanoparticles significantly increased microalgae productivity and enhanced nitrogen and phosphorus assimilation. The presence of nanoparticles also improved the quality of biomethane produced.
Article
Energy & Fuels
Yao Xiao, Asma Leghari, Linfeng Liu, Fangchao Yu, Ming Gao, Lu Ding, Yu Yang, Xueli Chen, Xiaoyu Yan, Fuchen Wang
Summary: Iron is added as a flocculant in wastewater treatment and the hydrothermal carbonization (HTC) of sludge produces wastewater containing Fe. This study investigates the effect of aqueous phase (AP) recycling on hydrochar properties, iron evolution and environmental assessment during HTC of sludge. The results show that AP recycling process improves the dewatering performance of hydrochar and facilitates the recovery of Fe from the liquid phase.
Article
Energy & Fuels
He Liang, Tao Wang, Zhenmin Luo, Jianliang Yu, Weizhai Yi, Fangming Cheng, Jingyu Zhao, Xingqing Yan, Jun Deng, Jihao Shi
Summary: This study investigated the influence of inhibitors (carbon dioxide, nitrogen, and heptafluoropropane) on the lower flammability limit of hydrogen and determined the critical inhibitory concentration needed for complete suppression. The impact of inhibitors on explosive characteristics was evaluated, and the inhibitory mechanism was analyzed with chemical kinetics. The results showed that with the increase of inhibitor quantity, the lower flammability limit of hydrogen also increased. The research findings can contribute to the safe utilization of hydrogen energy.
Article
Energy & Fuels
Zonghui Liu, Zhongze Zhang, Yali Zhou, Ziling Wang, Mingyang Du, Zhe Wen, Bing Yan, Qingxiang Ma, Na Liu, Bing Xue
Summary: In this study, high-performance solid catalysts based on phosphotungstic acid (HPW) supported on Zr-SBA-15 were synthesized and evaluated for the one-pot conversion of furfural (FUR) to γ-valerolactone (GVL). The catalysts were characterized using various techniques, and the ratio of HPW and Zr was found to significantly affect the selectivity of GVL. The HPW/Zr-SBA-15 (2-4-15) catalyst exhibited the highest GVL yield (83%) under optimized reaction conditions, and it was determined that a balance between Bronsted acid sites (BAS) and Lewis acid sites (LAS) was crucial for achieving higher catalytic performance. The reaction parameters and catalyst stability were also investigated.
Article
Energy & Fuels
Michael Stoehr, Stephan Ruoff, Bastian Rauch, Wolfgang Meier, Patrick Le Clercq
Summary: As part of the global energy transition, an experimental study was conducted to understand the effects of different fuel properties on droplet vaporization for various conventional and alternative fuels. The study utilized a flow channel to measure the evolution of droplet diameters over time and distance. The results revealed the temperature-dependent effects of physical properties, such as boiling point, liquid density, and enthalpy of vaporization, and showed the complex interactions of preferential vaporization and temperature-dependent influences of physical properties for multi-component fuels.
Article
Energy & Fuels
Yuan Zhuang, Ruikang Wu, Xinyan Wang, Rui Zhai, Changyong Gao
Summary: Through experimental validation and optimization of the chemical kinetic model, it was found that methanol can accelerate the oxidation reaction of ammonia, and methanol can be rapidly oxidized at high concentration. HO2 was found to generate a significant amount of OH radicals, facilitating the oxidation of methanol and ammonia. Rating: 7.5/10.
Article
Energy & Fuels
Radwan M. EL-Zohairy, Ahmed S. Attia, A. S. Huzayyin, Ahmed I. EL-Seesy
Summary: This paper presents a lab-scale experimental study on the impact of diethyl ether (DEE) as an additive to waste cooking oil biodiesel with Jet A-1 on combustion and emission features of a swirl-stabilized premixed flame. The addition of DEE to biodiesel significantly affects the flame temperature distribution and emissions. The W20D20 blend of DEE, biodiesel, and Jet A-1 shows similar flame temperature distribution to Jet A-1 and significantly reduces UHC, CO, and NOx emissions compared to Jet A-1.
Article
Energy & Fuels
Jiang Bian, Ziyuan Zhao, Yang Liu, Ran Cheng, Xuerui Zang, Xuewen Cao
Summary: This study presents a novel method for ammonia separation using supersonic flow and develops a mathematical model to investigate the condensation phenomenon. The results demonstrate that the L-P nucleation model accurately characterizes the nucleation process of ammonia at low temperatures. Numerical simulations also show that increasing pressure and concentration can enhance ammonia condensation efficiency.
Article
Energy & Fuels
Shiyuan Pan, Xiaodan Shi, Beibei Dong, Jan Skvaril, Haoran Zhang, Yongtu Liang, Hailong Li
Summary: Integrating CO2 capture with biomass-fired combined heat and power (bio-CHP) plants is a promising method for achieving negative emissions. This study develops a reliable data-driven model based on the Transformer architecture to predict the flowrate and CO2 concentration of flue gas in real time. The model validation shows high prediction accuracy, and the potential impact of meteorological parameters on model accuracy is assessed. The results demonstrate that the Transformer model outperforms other models and using near-infrared spectral data as input features improves the prediction accuracy.