JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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2020
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IF 4.495
Dou Chen,Gaoming Mo,Junmin Qian,Liu He,Qing Huang,Zhengren Huang
Polycarbonsilane (PCS) is an important precursor of silicon carbide (SiC) fibers and ceramics. The ceramic yield of PCS is relatively low, about 60 %, which may bring some deficiencies in its applications. In this work, a novel precursor cyano-polycarbosilane (PCSCN) is synthesized by hydrosilylation reaction between PCS and acrylonitrile using a rhodium-containing catalyst, although acrylonitrile is generally not easy for hydrosilylation. After introducing tiny amounts of cyano (-C≡N) groups into the PCS molecules, the ceramic yield of PCSCN can increase largely to over 80 %. The ceramization mechanism of PCSCN is investigated by FTIR, TG, XPS , ESR , NMR, Raman and XRD analyses. It is found that some crosslinking structures in PCSCN are formed between Si H bonds and C N groups from about 200 ℃, which can be responsible for the high ceramic yield. The existence of a little more N, O and free C elements in the pyrolysis products may inhibit the growth of crystalline β-SiC. Moreover, the PCSCN precursor can also be melt-spun into continuous fibers by tailoring its molecular weight and softening point. The oxidized PCSCN fiber with relatively low oxygen content can be pyrolyzed without melting, and the final SiC fiber with an oxygen content as low as 8.5 % is obtained.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2018
·
IF 4.908
Dan Luo,Wang Yin,Shengnan Liu,Ning Yang,Shuqian Xia,Peisheng Ma
Pyrolysis oil is a promising material for renewable energy through a hydrogenation process. However, the polymerization, initiated especially by pyrolysis oil water-soluble fraction (PS), is a big hurdle to hydrogenation. The types and structures of the polymerization chemicals, their polymerization mechanisms are very important for upgrading pyrolysis oil. This study firstly compared the polymerization rates of water-soluble fraction (PS) and water-insoluble fraction (PL) by accelerating aging fresh PS and PL at different temperatures (80 °C, 90 °C, 100 °C and 110 °C) for 24 h and at 110 °C for different durations (12 h, 24 h, 36 h, 48 h and 60 h), respectively. The thermogravimetric and differential thermogravimetry analysis results showed that PS polymerized much more rapidly than PL. Then, PS polymerization was further investigated by evaluating the changes in its physical properties (water content, viscosity and element content) and chemical compositions (gas chromatography and liquid chromatogram) before and after aging. The results showed that hydroxy aldehydes and ketones (especially glycoaldehyde, hydroxyacetone and levoglucosan), dicarbonyl compounds (especially succindialdehyde) and α, β-unsaturated carbonyl compounds (especially 3-methyl-2-cyclopenten-1-one and dehydrate resultants of some aldol condensation products) were mainly responsible for PS polymerization.
研究领域:
能源科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2022
·
IF 5.767
Tenglong Lv,Minggao Xu,Wei He,Yifan Zhang,Wang Li,Shubao Song,Jiuzhong Yang,Long Zhao,Lixia Wei
An experimental and kinetic modeling investigation of the pyrolysis of chlorobenzene (PHICL) was performed with a flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry in the temperature range of 800–1507 K and pressures of 30 to 760 torr. Eighteen pyrolysis products were identified and quantified. A detailed kinetic model describing the PHICL pyrolysis process was developed and validated against the available experimental results. The sensitivity analysis of PHICL pyrolysis shows that the PHICL consumption is most sensitive to the unimolecular decomposition reaction R2PHICL= o -C 6 H 4 +Cl at 30 Torr. The H-abstraction reaction of PHICL+Cl=R2PHICL+HCl plays a dominant role in PHICL consumption at 760 Torr. The mole distribution analysis and rate of production (ROP) analysis shows that PHICL tends to be decomposed via unimolecular decomposition reactions to produce small molecules such as o -C 6 H 4 , C 4 H 4 , C 4 H 2 , and C 2 H 2 at 30 Torr; while with pressure increasing, recombination reactions of chlorophenyl (RxPHICL ( x = 2–4)) radicals forming C 12 H 8 Cl 2 , and ipso -addition reactions of chlorophenyl/phenyl to PHICL yielding C 12 H 8 Cl 2 /C 12 H 9 Cl are critical to the consumption of the precursor, further leading to the formation of tricyclic chlorinated aromatic C 18 H 11 Cl.
研究领域:
化学工程
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环境科学
✓ 已验证
DOI
高影响因子
BIORESOURCE TECHNOLOGY
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2017
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IF 5.651
Yu Hong,Wanru Chen,Xiang Luo,Chengheng Pang,Edward Lester,Tao Wu
In this study, three different marine biomasses, i.e., microalgae-spirulina, chlorella and macroalgae-porphyra, were pyrolyzed in a laboratory-scale multimode-microwave cavity at 400, 550 and 700 °C. Ovalbumin and cellulose were also chosen as model compounds to simulate algae. The influence of heating rate on pyrolysis and the βi curves of different samples under different temperatures were studied in detail. The porphyra was found to be the most reactive and produced the largest gaseous fraction (87.1 wt%) amongst the three algae, which comprised of 73.3 vol% of syngas. It was found that nitrogenated compounds in bio-oil were derived from protein in algae while carbohydrate led to the formation of PAHs. For the production of bio-oil, protein-rich microalgae is favorable compared with porphyra due to their lower amount of PAHs, while porphyra is more suitable for the production of H 2 + CO rich gas product, which is comparable with that of conventional gasification processes.
研究领域:
能源生物学
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环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2016
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IF 3.652
Qiang Lu,Hui-yun Tian,Bin Hu,Xiao-yan Jiang,Chang-qing Dong,Yong-ping Yang
Fast pyrolysis of biomass will produce complex pyrolytic products. Hydroxyacetaldehyde (HAA) is one of the most important pyrolytic products, derived from fragmentation (ring scission) of holocellulose. In this study, density functional theory (DFT) calculations are employed to reveal the HAA formation mechanisms from fast pyrolysis of four holocellulose-based monosaccharides, i.e., β- d -glucopyranose, β- d -mannopyranose, β- d -xylopyranose and O -acetyl-β- d -xylopyranose. Moreover, the theoretical calculation results of the β- d -glucopyranose are confirmed by isotopic labeling fast pyrolysis experiments. The results indicate that during β- d -glucopyranose pyrolysis, the HAA is mainly derived from C1 C2, C5 C6 and C3 C4. The C2 C3 bond is easy to break via retro-aldol reaction to form 1,2-ethenediol (ED) which will tautomerize into the HAA from C1 C2 with high selectivity, accounting for the largest proportion of total HAA. The second largest origin of the HAA is the C5 C6 segment in multiple pathways with low energy barriers. However, these reactions to form the HAA from C5 C6 are thermodynamically unfavorable, and moreover, there are facile competing reactions to produce other products. Importantly, the HAA and levoglucosan (LG) are mainly formed via competing parallel pyrolytic pathways. Only a little HAA will be derived from the secondary cracking of LG. In addition, the HAA formation mechanisms from β- d -mannopyranose and β- d -xylopyranose are similar as those from β- d -glucopyranose. However, O -acetyl-β- d -xylopyranose behaves differently from the other three monosaccharides due to the acetyl group at C2 position. The HAA will be mainly derived from C4 C5, accompanied with the formation of acetic acid (AA) from scission of the acetyl branch.
研究领域:
生物质能
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化学工程
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理论计算
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2013
·
IF 3.599
Zhandong Wang,Lili Ye,Wenhao Yuan,Lidong Zhang,Yizun Wang,Zhanjun Cheng,Feng Zhang,Fei Qi
Methylcyclohexane is the simplest alkylated cyclohexane , and has been broadly used as the representative cycloalkane component in fuel surrogates. Understanding its combustion chemistry is crucial for developing kinetic models of larger cycloalkanes and practical fuels. In this work, the synchrotron vacuum ultraviolet photoionization mass spectrometry combined with molecular-beam sampling was used to investigate the species formed during the pyrolysis of methylcyclohexane and in premixed flame of methylcyclohexane. A number of pyrolysis and flame intermediates were identified and quantified, especially including radicals (e.g. CH 3 , C 3 H 3 , C 3 H 5 and C 5 H 5 ) and cyclic C6- and C7-intermediates (benzene, 1,3-cyclohexadiene, cyclohexene , toluene, C 7 H 10 and C 7 H 12 , etc.). In particular, the observation of cyclic C6- and C7-intermediates provides important experimental evidence to clarify the special formation channels of toluene and benzene which were observed with high concentrations in both pyrolysis and flame of methylcyclohexane. Furthermore, the rate constants of H-abstraction of methylcyclohexane via H attack, and the isomerization and decomposition of the formed cyclic C 7 H 13 radicals were calculated in this work. A kinetic model of methylcyclohexane combustion with 249 species and 1570 reactions was developed including a new sub-mechanism of MCH. The rate of production and sensitivity analysis were carried out to elucidate methylcyclohexane consumption, and toluene and benzene formation under various pyrolytic and flame conditions. Furthermore, the present kinetic model was also validated by experimental data from literatures on speciation in premixed flames, ignition delays and laminar flame speeds.
研究领域:
化学动力学
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燃料化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2014
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IF 3.07
Xinlai Wei,Zhi Wang,Yang Wu,Zhimin Yu,Jie Jin,Ke Wu
Various metal oxides, such as zirconia, titania, and alumina, were screened as solid acid catalysts in the fast pyrolysis of cellulose for levoglucosenone production. The liquid yields were affected by the properties of the catalyst, and an increase in levoglucosenone was observed with the addition of mesoporous metal oxides. Good catalytic properties were observed for anatase titanium oxide with an optimum surface area and pore diameter resulting in a levoglucosenone yield that was as much as 4.98%. The activities of calcined sulfated zirconia increased substantially compared to zirconia-impregnated sulfuric acid without calcination. In the presence of solid super-acid SO 4 2− /ZrO 2 , cellulose produced levoglucosenone in a 7.25% yield.
研究领域:
化学工程
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生物质能
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2021
·
IF 5.541
Rui Li,Xiaoqing Yin,Shiyi Zhang,Jinchu Yang,Mingqin Zhao
Amadori compounds, produced during Maillard reaction , are considered as precursors of flavor compounds . On the basis of Amadori compounds, herein two Amadori analogues, di- O -isopropylidene-2,3:4,5- β - D -fructopyranosyl alanine ester (A-ARP) and di- O -isopropylidene-2,3:4,5- β - D -fructopyranosyl proline ester (P-ARP), were chemically synthesized and their possibility as flavor precursors was evaluated by thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). TG-DTG analyses indicated that the samples were stable at room temperature , and the largest mass-loss rates ( T p ) were at 208 and 278 °C, respectively. Upon thermal pyrolysis, the major flavor substances were butan-2-one, ethyl propionate , furfural , and dl -limonene for A-ARP, while 2,5-dimethylfuran, heptan-2-one, acetophenone , and 1 H -pyrrole for P-ARP. The flavor profiles are different from that of corresponding Amadori compounds, and are influenced by pyrolytic temperatures. These results provide one method to regulate the species and amounts of the degraded flavor products. Finally, the possible mechanisms of the pyrolytic processes are proposed.
研究领域:
食品科学
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分析化学
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有机化学
✓ 已验证
产品关联
DOI
高影响因子
Energies
·
2022
·Vol. 15
·期 4
·1254
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IF 3.252
Hongyuan Qi,Huayi Jiang,Yanzhen You,Juan Hu,Yulong Wang,Zhe Wu,Hongxin Qi
In view of the high dielectric constant of magnetic nanoparticles, this paper intends to use it as a new type of microwave absorbing medium to accelerate the microwave pyrolysis process of oily sludge. Microwave thermogravimetric reaction and pyrolysis product staged collection devices were established, respectively. The main stage of pyrolysis process of oily sludge was divided based on the thermogravimetric experiments. Mechanism was studied through the characteristics of pyrolysis products and reaction kinetics simulation. Experimental results showed that the addition of magnetic ZnFe2O4particle did not change the microwave pyrolysis process of oily sludge and the pyrolysis efficiency could be improved. Pyrolysis process was divided into three stages, rapid heating and water evaporation stage (20~150 °C), light component evaporation stage (150~240 °C) and heavy component cracking stage (240~300 °C). Due to the addition of magnetic ZnFe2O4particles, the content of C4~C12increased by 3.5%, and the content of C18+decreased by 4.1%, indicating that more recombinant components participated in the reaction pyrolysis to form light gas components. The kinetic analysis showed that the activation energy of oily sludge decreased by 36.49% and the pre-exponential factor decreased by 91.39% in stage III, indicating that magnetic nanoparticles had good catalytic activity.Keywords:magnetic nanoparticles;oily sludge;microwave pyrolysis;thermogravimetric analysis;kinetics simulation
研究领域:
环境科学
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化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2022
·
IF 6.437
Hao Qi,Qirong Yang,Zhaoying Li,Chenyu Yang,Xinru Ma,Haoxi Ben
The mechanism of gas-phase products from pyrolysis of polysaccharides from Enteromorpha prolifera (PE) is researched. The sulfated polysaccharides are the most important polysaccharides in Enteromorpha prolifera . The molecular dynamics (MD) method is used to simulate the pyrolysis process of sulfated polysaccharides of Enteromorpha prolifera . Combined with the results of the pyrolysis simulations and density functional theory (DFT), rhamnose , glucuronic acid , glucose, and xylose are used as model compounds to estimate and calculate the reaction paths of hydrogen and carbon monoxide . In addition, fixed-bed pyrolysis experiments are performed with the above four monomers . The pyrolysis simulation results show that the pyrolysis process of sulfated polysaccharides is approximately divided into three stages: low-temperature, medium-temperature, and high-temperature stages. Gas-phase products are mainly produced in the high-temperature stage, and the main components of syngas are hydrogen, methane, and carbon monoxide. The simulation and experimental results show that pyrolysis of xylose is the most likely to generate hydrogen, followed by glucose, rhamnose, and glucuronic acid. The process of producing carbon monoxide from monomers goes through reactions such as dehydration, isomerization , C-C bond breakage, and decarbonylation . Moreover, the results of fixed-bed experiments indicate that when the four monomers are pyrolyzed individually, the highest proportions of hydrogen, carbon monoxide, and methane in the gas-phase products are obtained from the pyrolysis of xylose, glucuronic acid, and rhamnose. When the four monomers are mixed and then pyrolyzed, the proportion of hydrogen and carbon monoxide in the obtained gas-phase products decreases, and the proportion of carbon dioxide increases.
研究领域:
生物化学
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2023
·
IF 6
Li Wang,Ji-Xiang Guo,Xiao-Jun Zhang,Chen-Hao Gao,Rui-Ying Xiong,Wyclif Kiyingi,Dan Luo
Oil shale is of increasing interest as it is considered an essential alternative to traditional energy sources due to its abundant reserves. In this research, nanoscale Co/MOF and Ni/MOF were prepared by modified methods, and the catalytic pyrolysis mechanism of oil shale was studied using structural characterization and pyrolysis experiments. The TG and DTG curves show that MOF catalysts increase the total weight loss rate of oil shale pyrolysis and decrease the temperature corresponding to the initial temperature, final temperature, and maximum weight loss rate of oil shale pyrolysis. Kinetic analysis shows that Co/MOF and Ni/MOF catalysts reduce the activation energy of oil shale pyrolysis reaction by 32 KJ/mol and 25 KJ/mol, respectively. The change in the yield and composition of the products before and after catalytic pyrolysis was compared through the dry distillation experiment. It was found that MOF had a good catalytic effect, and the shale oil output was significantly increased. The FT-IR and GC/MS analysis of the catalytic pyrolysis of shale oil shows that the addition of Co/MOF and Ni/MOF catalysts is conducive to the increase of aromatics, olefins , and alkanes and the decrease of oxygen-containing compounds. The effect of the catalysts on the nature of the products and on the yields suggests that the Lewis and Bronsted acid groups on the surfaces of the MOF catalysts and that these can induce positive charges on carbon atoms in alkanes, alkenes etc to promote pyrolysis generate more oil.
研究领域:
能源化学
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催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2023
·Vol. 14
·期 1
·1-9
·
IF 16.6
Zang Ying,Lu Di-Qiu,Wang Kun,Li Bo,Peng Peng,Lan Ya-Qian,Zang Shuang-Quan
Catalysts capable of electrochemical overall water splitting in acidic, neutral, and alkaline solution are important materials. This work develops bifunctional catalysts with single atom active sites through a pyrolysis-free route. Starting with a conjugated framework containing Fe sites, the addition of Ni atoms is used to weaken the adsorption of electrochemically generated intermediates, thus leading to more optimized energy level sand enhanced catalytic performance. The pyrolysis-free synthesis also ensured the formation of well-defined active sites within the framework structure, providing ideal platforms to understand the catalytic processes. The as-prepared catalyst exhibits efficient catalytic capability for electrochemical water splitting in both acidic and alkaline electrolytes. At a current density of 10 mA cm −2 , the overpotential for hydrogen evolution and oxygen evolution is 23/201 mV and 42/194 mV in 0.5 M H 2 SO 4 and 1 M KOH, respectively. Our work not only develops a route towards efficient catalysts applicable across a wide range of pH values, it also provides a successful showcase of a model catalyst for in-depth mechanistic insight into electrochemical water splitting.
研究领域:
电化学
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催化
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材料科学
·
能量转换
✓ 已验证
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）