ENERGY CONVERSION AND MANAGEMENT
·
2022
·
IF 11.533
Tan Li,Kai Miao,Zhigang Zhao,Yuqing Li,Huiyuan Wang,Atsushi Watanabe,Norio Teramae,Kaige Wang
The product distributions of cellulose pyrolysis under different pressures, temperatures, and atmospheres were investigated using a high-pressure micropyrolyzer to clarify the pyrolysis reaction mechanism of cellulose decomposition with hydrogen. EGA-MS results shows that the increase in hydrogen pressure prolonged the second stage of cellulose pyrolysis, which was dominated by decarboxylation. Pyrolysis products of cellulose under helium mainly included levoglucosan, furfural, and acids, while cellulose hydropyrolysis mainly produced C5-C7 ketones, besides small amount of alcohols, aromatics and aliphatic hydrocarbons, and even small amount of phenolics. Carbon yield of ketones was as high as 27.2% from cellulose hydropyrolysis under 2.5 MPa hydrogen and 500 °C. The yield of liquid products and non–condensable hydrocarbons increased with elevated hydrogen pressure. The formation mechanisms of aromatics, phenolics, aliphatic hydrocarbons, aldehydes, ketones, and alcohols under hydrogen atmosphere were discussed. Acetaldehyde was produced by acids through a HDO reaction. C5-C7 chain ketones and cyclic ketones were generated by furfural through HDO and hydrocracking reactions. The Diels–Alder reaction to generate aromatics was enhanced by increasing pyrolysis temperature under hydrogen atmosphere. The reaction network of cellulose hydropyrolysis was also proposed.
研究领域:
化学工程
·
能源科学
✓ 已验证
DOI
高影响因子
FUEL
·
2024
·
IF 6.7
Li Zhou,Fashe Li,Wenchao Wang,Huicong Zhang,Yaozong Duan,Hua Wang
Phospholipids, as key trace constituents of biodiesel, can have complex effects on the performance of biodiesel. Exploring the mechanism of their influence on the pyrolysis and oxidation characteristics of biodiesel is crucial for controlling the generation and emission of pollutants. To this end, this study employed TG-FTIR-MS experimental technology and the ReaxFF-MD simulation method to investigate the effects of phosphatidylethanolamine (PE) on the activation energy ( E a ), gaseous product generation, and mechanism of Jatropha biodiesel pyrolysis and oxidation reactions. The results indicated that the addition of 400 ppm PE can reduce the pyrolysis E a of Jatropha biodiesel from 87.25 kJ/mol to 80.67 kJ/mol, consistent with simulated E a of 93.35 kJ/mol and 81.81 kJ/mol, respectively. This notably promoted the initial oxidation stage of the Jatropha biodiesel reaction, facilitating the generation of oxidation products such as CO and C 2 H 4 . In the pyrolysis reaction, PE promoted C 2 H 4 formation, primarily through reactions involving hydrocarbon small free radicals. In the oxidation reaction, the addition of PE increased the number and variety of active free radicals in the system, with the formation reactions of H 2 O and CH 2 O involving phosphorus-containing oxygen groups. Furthermore, a small amount of nitrogenous free radicals participates in the formation reactions of C 2 H 4 and CO.
研究领域:
能源科学
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化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
·
2018
·
IF 4.427
Yiqun Gan,Shengcun Ma,Xiaoqi Guo,Baiyang Chen,David Jassby
Chloral hydrate (CH) is a common disinfection by-product found in treated water, and its effective control is important to human health. This study evaluated the effects of some environmental factors (e.g., pH, CH dosage, typical ions) and operational variables (e.g., lamp power, irradiation time) on CH photolysis efficiency via low-pressure mercury lamp–induced ultraviolet (LPUV) at 254 nm. The results demonstrated that the photolysis rate increased significantly with increasing pH from 7.0 to 10.5 and lamp power from 6 to 12 W. Meanwhile, the presence of nitrate, iodide, or free chlorine facilitated CH photolysis, whereas the existence of natural organic matter hindered the process. Together, these factors may help explain varying CH photolysis in different types of waters: seawater > ultrapure water > tap water > lake water. In addition, the initial CH dosage also played an important role, with higher CH being degraded more slowly. Mechanistically, although no catalyst or oxidant was added, CH photolysis was to some extent inhibited by a hydroxyl radical quencher, tert -butyl alcohol, suggesting that indirect photolysis was also responsible for CH loss. In terms of reaction products, the CH photolysis yielded primarily chloride ions and carbon dioxide, thus supporting mineralization as the key pathway. The results may help better understand the control of CH in water using UV.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2020
·Vol. 11
·期 5
·1914-1921
·
IF 5.721
Xiaoxiao Qin,Xueyan Chen,Min Chen,Jianghao Zhang,Hong He,Changbin Zhang
Formaldehyde (HCHO) elimination at low temperature is of great interest for indoor air purification. In this work, 1 wt% Ru supported on CeO2 and Al2O3 catalysts were prepared by an impregnation method and subsequently tested for the catalytic oxidation of HCHO at low temperature. The activity of the Ru/CeO2 catalyst was significantly superior to the Ru/Al2O3 catalyst, achieving complete conversion of 130 ppm HCHO at 90 °C with a GHSV of 100 000 mL gcat−1 h−1. Brunauer–Emmett–Teller (BET) measurements, X-ray powder diffraction (XRD), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photoelectron spectroscopy (XPS) and H2-temperature-programmed reduction (H2-TPR) were carried out to characterize the physical and chemical properties of the catalysts. The results revealed that RuOx species, rather than Ru0, were directly responsible for the HCHO oxidation over Ru/CeO2, and the excellent performance of Ru/CeO2 was mainly attributed to the strong interaction between Ru and CeO2, which induced a high dispersion and high redox capacity of RuOx species. The reaction mechanism of HCHO oxidation was also investigated using in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). It was shown that the HCHO oxidation over the Ru/CeO2 and Ru/Al2O3 catalysts followed the same pathway of the direct formate oxidation (HCHO → HCOO + OH → H2O + CO2).
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Journal of the Australian Ceramic Society
·
2024
·
IF 1.8
Wang Xingguo,Li Xin,Chen Bin,Tang Jian,Chang Shilun,Xu Chen
The reaction mechanism of TiB 2 synthesized by carbothermal reduction is unclear due to a lack of thermodynamic research. In this work, the phase diagrams of TiO 2 -B 2 O 3 -C system were analyzed at a large temperature range (900–1800 °C), illustrating that Ti 4 O 7 , Ti 3 O 5 , and TiC were the main intermediate products. According to the Gibbs free energy minimum principle, the synthesis pathways of the main intermediate products and the target product TiB 2 were discussed, respectively. Based on the thermodynamic research, the reaction mechanism of TiO 2 -B 2 O 3 -C system was proposed and verified by experimental research at 900–1500 °C. X-ray-pure TiB 2 powder was synthesized at 1500 °C for 30 min and the possible reaction mechanism could be divided into three stages: TiO 2 (anatase)→TiO 2 (rutile)→Ti 3 O 5 , TiC →TiB 2 .
研究领域:
材料科学
·
热力学
✓ 已验证
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Boyin Yan,Zhiquan Liu,Ying Liu,Rui Huang,Yongpeng Xu,Dongmei Liu,Fuyi Cui,Wenxin Shi
β- N -Methylamino- l -alanine (BMAA), a new cyanobacterial toxin , is found in different aquatic ecosystems worldwide and is to threaten the human nervous system. Therefore, it is important for water plants to develop feasible methods to counter the effects of BMAA. In this study, the removal of BMAA by chlorine, as well as its intermediate products, at different pH values and the mechanism of pH on the removal BMAA were investigated. The results showed that the chlorination of BMAA is in accordance with the second-order kinetics model. The reaction rate of chlorinated BMAA increased with the increase in the concentration of chlorine. The pH of the solution significantly affected the reaction rate. The apparent kinetic constant ( k app ) decreased from 6.00 × 10 3 M − 1 ·min − 1 to 35.5 M − 1 ·min − 1 when the pH increased from 4.5 to 9 in the chlorine concentration of 32.23 μM. It is probable that the species distribution and proportion of BMAA and chlorine at different pH values were the main causes of this phenomenon. Additionally, the chlorination reaction consisted of four elementary reactions and hydrogen ions were beneficial to the reaction. The temperature also affected the reaction rate and the activation energy of the reaction was 16.6 ± 1.99 kJ·M − 1 . A variety of degradation products were detected and the path of degradation was speculated. Chlorination, dechlorination , and decarboxylation were the main processes of oxidative degradation. Furthermore, the composition of the degradation products was the same at different pH values.
研究领域:
环境科学
·
毒理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Ruxin Peng,Jihai Shao,Yuanlin Xie,Anwei Chen,Liang Peng,Qingru Zeng,Si Luo
Being that the influence of organic ligands on contaminant removal by nanoscale zero valent iron (nZVI) has been explored in quite a few studies, there is little information on reaction mechanisms of the ZVI-ligand system under different aeration conditions. The degradation of nitrobenzene (NB) by nZVI-oxalic acids (OA) was investigated under N 2 , O 2 and without aeration conditions. From the findings, it was evident that OA dramatically improved NB degradation by nZVI with all of the aeration conditions. Approximately 100% of NB was degraded by nZVI-OA+N 2 system after 60 min of reaction, followed in effectiveness by nZVI-OA+ without aeration (95%) as well as nZVI-OA+O 2 (85%). Operation parameters including OA concentration and pH had significant effect on the removal of NB in the nZVI-OA system. 3 mM OA concentration and pH 3.0 were found to be favourable. The Fe 2+ , total dissolved iron concentrations, pH and ORP values in the nZVI-OA systems had also been monitored. Intermediates and trapping experiments showed that reduction played a fundamental role in the NB degradation by nZVI-OA under N 2 or without aeration conditions. The formation of Fe(OA) 0 and Fe(OA) 2 2− complexes had lower standard ORP, which could improve the strength of reductant in the systems, and thus resulting in an increased degradation efficiency of NB by nZVI-OA+N 2 . Under O 2 aeration condition, the NB degradation process could be regarded as an oxidation . In the meantime, OA promoted the production of reactive oxidants species by speeding up the oxidation rates of Fe 2+ by O 2 and H 2 O 2 . Summarily, the improved reactivity of nZVI was largely as a result of the strong complexation ability of OA.
研究领域:
环境科学
·
化学
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2018
·
IF 6.653
Jing Chen,Nannan Wu,Xinxin Xu,Ruijuan Qu,Chenguang Li,Xiaoxue Pan,Zhongbo Wei,Zunyao Wang
Potassium ferrate [Fe(VI)] is a promising oxidant widely used in water treatment for the elimination of organic pollutants. In this work, the reaction kinetics, products, and mechanisms of the antimicrobial agent chlorophene (CP) undergoing Fe(VI) oxidation in aqueous solutions were investigated. CP is very readily degraded by Fe(VI), with the apparent second-order rate constant, k, being 423.2 M–1 s–1 at pH 8.0. A total of 22 oxidation products were identified using liquid chromatography–quadrupole time-of-flight–mass spectrometry , and their structures were further elucidated using tandem mass spectrometry. According to the extracted peak areas in mass spectra, the main reaction products were the coupling products (dimers, trimers, and tetramers) that formed via single-electron coupling. Theoretical calculations demonstrated that hydrogen abstraction should easily occur at the hydroxyl group to produce reactive CP· radicals for subsequent polymerization. Cleavage of the C–C bridge bond, electrophilic substitution, hydroxylation, ring opening, and decarboxylation were also observed during the Fe(VI) oxidation process. In addition, the degradation of CP by Fe(VI) was also effective in real waters, which provides a basis for potential applications.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2017
·Vol. 132
·期 1
·327-336
·
IF 1.953
Zhang Han,Liu Shang-Hao,Liu Feng,Yan Shi-Long,Li Wei-Yi
The thermogravimetric techniques and differential thermal analysis have been employed in this work to analyze the macro-reactions mechanism of the silicon delay composition. Quantum chemical calculation has been performed to study the microscopic mechanism of the main reaction (Pb 3 O 4 + Si) at the density functional theory BPW91/6−311++G(d, p) level of theory with the SDD implicit solvent model. Our results have shown that in the silicon delay composition, the strongest reaction exothermic peak is originated from the reaction between Pb 3 O 4 cluster and Si. For the microscopic reaction process of Pb 3 O 4 and Si containing two reaction pathways, we found that they proceeded in this manner, Pb 3 O 4 + Si → SiO + 3PbO and SiO + Pb 3 O 4 → SiO 2 + 3PbO, with a total of four reaction channels. In addition, we have determined the reaction sites by making use of the charge distribution from natural bonding orbital analysis and the HOMO–LUMO gap of the reactants.
研究领域:
化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2022
·
IF 6.633
Yingqing Zhao,Rui Liu,Christian Marcus Pedersen,Zhenzhou Zhang,Zhaohui Guo,Honghong Chang,Yingxiong Wang,Yan Qiao
Lactic acid (2-hydroxypropionic acid, LA) can be produced from abundant and renewable biomass resources via chemocatalytic processes, which exhibited high potential for meeting its tremendous demand in a wide range of applications. The basic Ba(OH) 2 could efficiently catalyze the conversion of d -glucose into LA. In the present study, by utilizing various NMR techniques including, chemical shift titration, 2D diffusion ordered spectroscopy (DOSY) analysis, heteronuclear singular quantum correlation ( 1 H– 13 C HSQC), the binding sites and catalytic interaction between d -glucose and catalyst were clarified. The experimental results by NMR and electrospray ionization mass spectrometry (ESI–MS) were used to explore the reaction mechanism. Experimental results disclosed that the catalyst, Ba(OH) 2 , may exist in the form of [Ba(OH)(H 2 O) 2 ] + under the reaction condition. The OH – of [Ba(OH)(H 2 O) 2 ] + is attached to the C5-O of d -glucose, and Ba 2+ is connected to the C1-O of d -glucose. Herein, we suppose that Ba(OH) 2 and d -glucose interact and form a complex, d -glucopyranose-[Ba(OH)(D 2 O) 2 ] + . Furthermore, when the reaction was performed in D 2 O, we were surprised to find that LA underwent varying degrees of deuteration. The reaction mechanism, binding sites and deuteration of the product have shed light on the efficient conversion of biomass to LA.
研究领域:
生物化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
RUSSIAN JOURNAL OF APPLIED CHEMISTRY
·
2023
·Vol. 95
·期 10
·1618-1626
·
IF 0.9
Ren Qinghui,Qian Linfeng,Yao Yanhui,Wen Yazhou,Shi Xiaohua
Abstract Cyanuric acid is an organic intermediate widely used in organic synthesis, and the traditional production method of cyanuric acid is the pyrolysis urea method. Due to the shortcomings of uneven mass transfer, many by-products and poor environmental friendliness, the production of cyanuric acid is extremely limited. In this paper, an effective method has been developed to synthesize cyanuric acid with high yield in a short period of time through the addition-elimination reaction of dihydric alcohol and urea under alkaline conditions. The reaction time, molar ratio of reactants, reaction temperature and other influencing factors were studied. Under optimized conditions, the yield of cyanuric acid is over 90%. And further the proposed reaction mechanism is verified. The synthetic method provided in this article has the advantages of easy availability of raw materials and reusability, simple operation and short reaction time, which makes the method novel and environmentally friendly.
研究领域:
有机化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2018
·
IF 0
Yucui Hou,Zengqi Lin,Muge Niu,Shuhang Ren,Weize Wu
The conversion of abundant renewable cellulose into versatile formic acid (FA) is a potential process for efficient energy storage and application. Vanadium(V)-catalyzed oxidation with O2 in acidic aqueous media now is the most common method to realize the FA production from cellulose with both high yields and high purity. However, vanadium-based catalysts are difficult to synthesize and expensive. Thus, the seeking for cheaper catalysts with the same high efficiency is expected. In this work, after testing a variety of metal salts in acidic aqueous solution for the conversion of cellulose under O2, iron(III) was found as a cheaper and readily available catalyst for FA formation, with a comparable yield (51.2%, based on carbon) with that of vanadium(V). The effect of reaction parameters was studied. The competition between oxidation and hydrolysis was found and discussed in detail. FeCl3 and H2SO4 can accelerate oxidation and hydrolysis, respectively, whereas suppress the other. The effects can reflect on the product distribution. Intermediates were found and the pathway from cellulose to products was reasonably proposed. The reusability of the catalytic system shows good performance after four runs. The mechanism study suggests a catalytic ability by a mutual transformation between iron(III) and iron(II), where iron(III) oxidizes substrates to iron(II) that is reoxidized by O2.
研究领域:
化学
·
能源科学
·
催化科学
✓ 已验证
DOI
PubMed
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