JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2021
·
IF 5.541
Fanggang Liu,Lijun Jin,Yanpeng Ban,Haoquan Hu
To understand the pyrolysis behavior of long linear alkanes, six n-alkanes (n-C n H 2n+2 , n = 10, 12, 13, 14, 15, 16) were conducted by pyrolysis coupled with photoionization molecular-beam mass spectrometer at pressure below 10 Pa and temperature between 200 °C and 1000 °C. Lots of important alkyl and alkenyl radicals (CH 3 , C 4 H 9 , C 8 H 15 , C 9 H 19 , C 3 H 5 , C 5 H 9 , etc.), which are the direct evidence to understand the pyrolysis reaction pathway, were real-time detected by mass spectral detector. The results suggested that the predominant pyrolysis mechanism of n-alkanes is a free-radical chain mechanism, beginning with the C C bond homolysis of n-C n H 2n+2 to produce primary alkyl radicals (C m H 2m+1 , m < n) and termination by β C-H homolysis and mutual combination of radicals. The chain is propagated by the β C-C homolysis and H-abstraction of primary alkyl radicals to produce secondary alkyl radicals (C h H 2h+1 ), and then the β C-C homolysis and H-abstraction of the secondary alkyl radicals to form alkyl/alkenyl radicals (C h H 2h+1 /C k H 2k-1 , h ≤ n, k < n-3) and alkenes (C k H 2k /C k H 2k-2 ) and the hydrogen-shift to form free-radical isomers. During the process, H-abstrction, and hydrogen-shift reactions exist as a synergistic reaction. In addition, the position of free radical in alkyl isomers is closer to the central carbon at low temperature. With the increase of temperature, 2-C m H 2m+1 radical are gradually dominated.
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高影响因子
Journal of Materials Chemistry C
·
2021
·Vol. 9
·期 38
·13447-13459
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IF 7.393
Junyao Shen,Danfeng Zhang,Qibai Wu,Yan Wang,Heng Gao,Jiale Yu,Guoxun Zeng,Haiyan Zhang
Given its easy-to-tailor microstructure with mixed nanodomains including amorphous and pseudo-graphitic parts, hard carbon (HC) as a type of non-graphitizable carbon promises to play a role in extended selection for novel metal/carbon microwave absorbers. Herein, we report the preparation of FeCoNi@HC composites as electromagnetic (EM) absorbers at different pyrolysis-controlled temperatures, derived from FeCoNi nanosheets (NSs)@polyimide (PI) composites. According to suitable pyrolysis treatments, FeCoNi@HC composites exhibit a wide range of mixed morphologies constituted of nanosheets and nanoparticles: original FeCoNi NSs are thermally converted into a particle-like structure as the core; the HC derived from the polyimide (PI) matrix inherits the original framework of the FeCoNi NSs for varying degrees of pyrolysis as the shell. The heat treatments also strongly influence the inner HC structural properties, including defect feature and graphitization degree. Treated by a moderate degree of pyrolysis, the optimal sample achieves decent enhancements of lossy attenuations (e.g., dielectric/magnetic losses) and promoted impedance matching for excellent EM absorption performances. The minimum reflection loss (RL) of the optimal sample is −61.12 dB, along with an effective absorption bandwidth (RL ≤ −10 dB) of 5.53 GHz. We anticipate that this work may enrich the survey of metals/carbon absorbers with non-graphitizable carbon supports.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2021
·
IF 5.541
Xin Zhong,Hu Wang,Qingming Zuo,Zunqing Zheng,Jinglan Wang,Wenhao Yin,Mingfa Yao
Polyoxymethylene dimethyl ethers (DMM n ) is regarded as a potential alternative fuel for transportation utilization. The jet stirred reactor (JSR) pyrolysis of DMM 1−3 was studied at temperatures of 450∼1080 K and pressures of 1.03 atm with the residence time (τ) of 2 s. A gas chromatography/mass spectrometry (GC–MS/FID) was used to detect and provide reliable pyrolysis experimental data. Seven key pyrolysis products were detected and measured in the present work, including fuel, methyl formate, methanol, acetaldehyde, methane, ethane and ethylene. A detailed kinetic model of DMM 1−3 pyrolysis was elaborated. Both rate of production (ROP) and sensitivity analysis were performed to reveal the DMM 1−3 pyrolysis processes. Results show that the chemical kinetic simulation can reproduce the consumption of fuel and most intermediate species reasonably well. With the increase of n from 1 to 3 inside DMM 1−3 , the reactivity increases evidently and the initial pyrolysis temperature decreases significantly, which is mainly resulted from different fuel-specific chain initiation reactions of DMM 1−3 . Methane and methyl formate are two detected key species with relatively significant concentrations. It was revealed that the fuel-specific chain initiation reactions of DMM 1−3 can also significantly affect the production and consumption paths of methyl formate. In addition to the major production and consumption paths of formaldehyde, two key competitive channels were found to perform relatively high negative sensitivity to formaldehyde production of DMM 2 and DMM 3 .
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高影响因子
JOURNAL OF NANOPARTICLE RESEARCH
·
2019
·Vol. 21
·期 3
·1-11
·
IF 2.009
Qin Ju,Zhang Limei,Yang Rui
In this paper, a novel fluorescence carbon dots (FCDs) were proposed to use folic acid as the sole reactant via the pyrolytic way. The gotten FCDs were uniform in size distribution and had an excitation-independent emission feature, and their fluorescence quantum yield was 39.09%. Without additional modification, the acquired FCDs could be used to detect isoniazid by the fluorescence quenching pattern. The reaction mechanism was the synergy of the internal filtration effect and the static quenching effect. The linear range of the detection of isoniazid was 4.0–140 μM, and the detection limit was 1.15 μM. Therefore, the method for the determination of isoniazid was put forward. The method was applied to the detection of isoniazid in isoniazid tablets with the recovery rates of 98.12 to 102.67%, and the results were satisfactory.
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高影响因子
CARBON
·
2019
·
IF 7.466
Yiwen Hu,Yongxin Wang,Chunting Wang,Yuwei Ye,Haichao Zhao,Jinlong Li,Xiaojiang Lu,Chunlong Mao,Shanjun Chen,Jinming Mao,Liping Wang,Qunji Xue
A simple and low-cost bottom-up method for the preparation of water-soluble Carbon dots (CDs) by tuning the carbonization degree of ammonium citrate. The structure and morphology of CDs were characterized by Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). And the investigation on the lubricating property and inhibition effect of CDs as nanoadditives of water-based lubricants is discussed in this work. The results show that the CDs as eco-friendly nanoadditives exhibit low friction coefficient , outstanding wear-resistance and excellent inhibition effect.
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高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2019
·
IF 3.47
Ziguo Yuan,Xin Zhang,Qian Yao,Ying Zhang,Yao Fu
In this study, a series of catalysts including different metal oxides loading on HZSM-5(Si/Al = 25) and cobalt oxides loading on different supports were synthesized to catalyze fast pyrolysis (CFP) of biomass derived polylactic acid (PLA) to produce acetonitrile under ammonia atmosphere. Both the metal and the acid of the catalyst had a crucial influence on the yield of acetonitrile and Co/HZSM-5(25) produced most acetonitrile. Other factors that might affect the product distribution including cobalt loading, reaction temperature, resident time and NH 3 flow rate have been investigated systematically. Under the optimized CFP condition (650 ℃; resident time 2.4 s; NH 3 flow rate 80 ml/min), the carbon yield and selectivity of acetonitrile in liquid product reached 50.2% and 83.6%, respectively. The possible reaction pathway from PLA to acetonitrile was also studied and proposed. PLA firstly cracked into lactic acid through thermal decomposition and formed lactide at the same time. Then lactic acid and lactide cracked into low-molecular aldehydes, ketones and acids. These aldehydes and ketones reacted with ammonia to form imines, acids to amides, and finally to acetonitrile and small amount of proponitrile under the catalysis of Co/HZSM-5 catalyst.
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高影响因子
Journal of Energy Chemistry
·
2019
·
IF 5.162
Bin Hu,Qiang Lu,Yu-ting Wu,Wen-luan Xie,Min-shu Cui,Ji Liu,Chang-qing Dong,Yong-ping Yang
The catalytic fast pyrolysis of cellulose impregnated with phosphoric acid (H 3 PO 4 ) offers a promising method for the selective production of levoglucosenone (LGO), a valuable anhydrosugar product. However, the fundamental mechanism for selective LGO formation is unclear. Herein, quantum chemistry calculations and catalytic fast pyrolysis experiments were performed to reveal the formation mechanism of LGO in H 3 PO 4 -catalyzed cellulose pyrolysis. H 3 PO 4 significantly decreased the energy barriers of the pyrolytic reactions and altered the competitiveness of the LGO formation pathways, promoting LGO formation. Through different pathways in the non-catalytic and H 3 PO 4 -catalyzed conditions, LGO is mainly produced from the primary decomposition of glucose units of cellulose and secondary conversion of levoglucosan. The major catalytic formation pathways of LGO comprise similar reactions, with dehydration at the 3-OH + 2-H site as the rate-determining step. Importantly, secondary conversion of 1,4;3,6-dianhydro-α- d -glucopyranose is not feasible for LGO formation, in contrast to previous reports. In addition, a high degree of polymerization is beneficial for the selectivity of LGO formation in the catalytic process, because the glycosidic bond is important for the formation of the bicyclic structure (1,5- and 1,6-acetal rings).
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Yunqiang Yi,Guoquan Tu,Pokeung Eric Tsang,Zhanqiang Fang
The effects of the pyrolysis temperature on the Fenton-like catalytic performance of magnetic biochar remain unclear. In this study, magnetic biochar (SMBC300, SMBC400, SMBC500) was synthesised at various temperature (300 °C, 400 °C and 500 °C) and used for the Fenton-like degradation of metronidazole. The characterisation results demonstrated the similarity of functional groups and the species of iron oxides in three types of magnetic biochar. Moreover, the size distribution of iron oxides in these composites were obviously affected by the pyrolysis temperature. Metronidazole was rapidly and completely degraded by SMBC400 coupled with H 2 O 2 , and its kinetic rate constant was approximately 1.86 and 3.04 times higher than those of SMBC300 and SMBC500, respectively. Electron spin resonance and free radical quenching experiments showed that obvious differences in the ability of three types of magnetic biochar can heterogeneously activate H 2 O 2 to generate OH, and that surface-bound OH plays a key role in the degradation of metronidazole. The differences in Fe (II) content among the types of magnetic biochar were the main reason for the differences in catalytic performance. The degradation of metronidazole by various species of iron oxides showed that FeO was the key component in the catalytic performance of magnetic biochar. This study confirms that magnetic biochar prepared at 400 °C has the best performance in the Fenton-like degradation of metronidazole.
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Sustainable Energy & Fuels
·
2018
·Vol. 2
·期 8
·1855-1862
·
IF 0
Jiajin Liang,Jiao Chen,Shubin Wu,Chao Liu,Ming Lei
Comprehensive understanding of cellulose pyrolysis is critical to valuable chemical and liquid fuel generation in biomass-based biorefining processes. Herein, a specific tubular reactor was designed to observe the cellulose appearance alteration corresponding to the chemical structure evolution in various pyrolysis stages. The appearance of cellulose changed from white powder to light brown powder below 300 °C as its crystal lattice thermal expansion and the degree of crystallinity decrease. Cellulose began to depolymerize at 300 °C accompanied with the dehydration of pinacol and primary product levoglucosan generation. 325–350 °C was the critical pyrolysis stage for cellulose. The intermediate state was formed accompanied with a series of thermochemical reactions. All the typical signals from FTIR, 13C CP/MAS NMR disappeared when the temperature was up to 350 °C. The percentages of C, H, and O conversion to the volatile products were up to 35%, 55% and 60%, respectively, along with β-1,4-glycosidic bond cleavage, decarboxylation, and decarbonylation reactions. Meanwhile, CO2, CO, and CH4 were measured using a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometer (TG-FTIR) in the slow pyrolysis process. The increasing C/H and C/O ratios in the carbonation stage enhanced the aromaticity of biochar. Furthermore, electron paramagnetic resonance (EPR) analysis indicated that it tended to form carbon-centered radicals.
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JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2015
·
IF 3.564
Zhi-bo Zhang,Qiang Lu,Xiao-ning Ye,Wen-tao Li,Ying Zhang,Chang-qing Dong
A new technique was proposed to selectively produce 4-ethyl phenol (4-EP) from low-temperature catalytic fast pyrolysis of certain herbaceous biomass, while 4-vinyl phenol (4-VP) could be selectively produced from non-catalytic fast pyrolysis process. In this study, Pd/SBA-15 catalysts were prepared, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique was applied for both ex situ and in situ catalytic fast pyrolysis of bagasse . The results indicated the 4-EP could be selectively produced from both catalytic methods. During the ex situ catalytic pyrolysis process, the bagasse would decompose to form 4-VP which was then hydrogenated by the Pd/SBA-15 catalyst to be 4-EP. During the in situ catalytic pyrolysis process, the Pd/SBA-15 catalyst would catalyze the decomposition and hydrogenation of bagasse to directly produce 4-EP. Certain pyrolytic products would serve as the hydrogen-donors (H-donor) for the formation of 4-EP. The selectivity of the 4-EP from the ex situ catalytic process was a little better than that form the in situ catalytic process. The highest 4-EP yield from ex situ catalytic pyrolysis of bagasse was around 2.0 wt%, obtained at the pyrolysis temperature of 350 °C and catalyst-to-biomass ratio of 1.5.
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高影响因子
BIORESOURCE TECHNOLOGY
·
2013
·
IF 4.75
Huiyan Zhang,Mengmeng Luo,Rui Xiao,Shanshan Shao,Baosheng Jin,Guomin Xiao,Ming Zhao,Junyu Liang
Chemical liquid deposition (CLD) with KH550, TEOS and methyl silicone oil as the modifiers was used to modify ZSM-5 and deposit its external acid sites. The characteristics of modified catalysts were tested by catalytic conversion of biomass pyrolysis-derived compounds. The effects of different modifying conditions (deposited amount, temperature, and time) on the product yields and selectivities were investigated. The results show KH550 modified ZSM-5 (deposited amount of 4%, temperature of 20 °C and time of 6 h) produced the maximum yields of aromatics (24.5%) and olefins (16.5%), which are much higher than that obtained with original ZSM-5 catalyst (18.8% aromatics and 9.8% olefins). The coke yield decreased from 44.1% with original ZSM-5 to 26.7% with KH550 modified ZSM-5. The selectivities of low-molecule-weight hydrocarbons (ethylene and benzene) decreased, while that of higher molecule-weight hydrocarbons (propylene, butylene, toluene, and naphthalene) increased comparing with original ZSM-5.
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PubMed
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2015
·
IF 3.564
Xiao-ning Ye,Qiang Lu,Wen-tao Li,Pan Gao,Bin Hu,Zhi-bo Zhang,Chang-qing Dong
A new technique was proposed to selectively produce nicotyrine, a valuable alkaloidal product, from catalytic fast pyrolysis of tobacco mixed with the Pd/C catalyst. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed to investigate the effects of pyrolysis temperature and catalyst-to-tobacco ratio on the selective nicotyrine production. The actual nicotyrine yields under different reaction conditions were quantitatively determined. Moreover, the catalytic activity of the Pd/C catalyst was compared with those of the activated carbon (AC), Ru/C and Pd/SBA-15 catalysts. The results indicated that during the catalytic fast pyrolysis process, the Pd/C catalyst possessed promising dehydrogenation capability to selectively convert the nicotine in tobacco into the nicotyrine, and it performed much better than the other three catalysts. The maximal nicotyrine yield reached as high as 2.80 wt%, obtained at the pyrolysis temperature of 400 °C and catalyst-to-tobacco ratio of 2.
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高影响因子
危险品化学品经营许可证（带存储）