POLYMER DEGRADATION AND STABILITY
·
2020
·
IF 4.032
Peng Wang,Ming Liu,Qichao Ran
Based on the weight loss and small molecule volatiles released during the thermal curing process of three kinds of benzoxazines , bisphenol A/aniline type benzoxazine (BA-a), p-cresol/diamine type benzoxazine (MPH-mda) and 2,4-xylenol/4,4′-methylenebis-(2,6-diisopropyl) aniline type benzoxazine (DMPH-mdpa), their curing mechanisms and the weight-loss mechanisms were studied. The weight-loss ratios and structure changes of these benzoxazines during the curing process were studied by weighing method, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The volatiles released from these benzoxazines during different curing stages were collected by a self-made experimental device. The structures of these volatiles were characterized by FTIR and proton nuclear magnetic resonance spectroscopy ( 1 H NMR). The results showed that the mixtures of imine , triazine , aniline and Schiff base were released from the cracking of the intermediate during the thermal curing of BA-a. Compared with BA-a, the weight loss of MPH-mda was smaller, and its volatile was a small amount of stable diamine type Schiff base. For DMPH-mdpa, because all active reaction points on benzene ring were occupied by alkyl groups , it cannot form effective polymer structures after ring-opening reactions, which led to that DMPH-mdpa had the most weight loss during the curing process, and mainly generated phenol type volatiles.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL RESEARCH
·
2025
·
IF 7.7
Bo Song,Zhenxing Shen,Qingzhu Tian,Guiling Zhou,Qin Peng,Hao Fan,Jia Liu
Volcanic rock is a natural mineral with a porous structure and rich in various metal oxides. It has been used in environmental applications such as water and soil pollution remediation as stable chemical properties and low cost. In this work, volcanic rock was used in the field of nitrogen oxide control, and the feasibility of preparing NH 3 - Selective Catalytic Reduction catalyst was evaluated. The catalyst AVR-10Mn-450 was prepared by acidification-impregnation-calcination process, and it can achieve more than 90 % denitration effect at 175 °C, 25000 h −1 . It removes nitrogen oxides through the Eley–Rideal and Langmuir–Hinshelwood pathways. AVR-10Mn-450 has the advantages of simple preparation and low cost compared with the mainstream nano-denitration catalysts. It can be applied to the pretreatment of industrial flue gas such as cement plant or glass plant, thereby extending the service life of the precious metal or nano-catalyst at the back end. This work not only realizes the high-value resource utilization of volcanic rock, but also reduces the production cost of denitration catalyst.
研究领域:
环境科学
·
催化化学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2021
·Vol. 12
·期 3
·737-749
·
IF 6.119
Zhicheng Xu,Yuran Li,Yuting Lin,Bin Wang,Panting Gao,Tingyu Zhu
The reduction of NO by CO was proposed to be applied for regeneration gas to remove NOx from industrial flue gas with activated carbon purification technology. To improve the activity and sulfur resistance for the reduction of NO by CO in regeneration gas, Cu and Fe modifications on activated carbon were investigated. And various samples were characterized by XRD, XPS, TPD, H2-TPR, in situ DRIFTS and DFT calculations to explain the reaction mechanism and poisoning mechanism. The synergistic effects of oxygen-containing functional groups and metal sites show that –COOH acts as an anchor site for metals and that C–O–C acts as a protective site for Fe3+ under a SO2 atmosphere. Cu2+ sites have a high activity at low temperatures due to the large amount of adsorbed NO and the intermediate NOx− participating in the reaction with the NOx− pathway. Fe3+ sites have a high activity at high temperatures due to the high N–O dissociation activity with the *N pathway and –NCO pathway. DFT calculations proved that the binding Cu2+ and Fe3+ sites have higher activity than free Cu2+ and Fe3+ sites. A high content of SO2 exhibits various poisoning effects, mainly including the sulfation of metal sites, deposition of S, and consumption of CO. AC-Fe-H exhibits excellent resistance and stability against SO2 and H2O due to less S deposition caused by consumption through the S–CO reaction, slight sulfation caused by the protective effect of Fe2+ and C–O–C on Fe3+ sites and better hydrophobicity.
研究领域:
环境科学
·
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
Desalination and Water Treatment
·
2024
·
IF 1
Shifeng Li,Feng Lu,Shuhua Yao,Shuyan Zang
The mesoporous goethite synthesized by the hydrothermal method was employed to remove selenate (Se(VI)) and selenite (Se(IV)) from wastewater. The adsorption data of kinetics and isotherms were determined and fitted with different models, and the potential adsorption mechanism was discussed according to X-ray photoelectron spectroscopy (XPS) analysis. The maximum adsorption capacities of Se(IV) and Se(VI) on the mesoporous goethite are 71.07 and 21.07 mg/g at 25°C, respectively, which are about two orders of magnitude higher than the natural goethite. The XPS results revealed that the Se(IV) was adsorbed on the surface of the mesoporous by the formation of the inner-sphere complex, but the outer-sphere complexes are formed with Se(IV). The meso-porous goethite is expected to be a potential adsorbent for Se removal from industrial selenium- containing wastewater on a large scale for its properties of easy-preparation and less cost compared with classic nanomaterials.
研究领域:
环境科学
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2020
·
IF 7.888
Xuerong Zhou,Xiang Li,Roel Prins,Jinyin Lv,Anjie Wang,Qiang Sheng
CoP and Co 2 P were prepared by temperature-programmed reduction of the mixtures of Co(OH) 2 and H 3 PO 3 with stoichiometric P/Co ratios, but their surfaces were still enriched in phosphorus. Based on the product distributions of the hydrodesulfurization (HDS) of dibenzothiophene (DBT), 1,2,3,4-tetrahydro-dibenzothiophene (TH-DBT), and 1,2,3,4,4a,9b-hexahydro-dibenzothiophene (HH-DBT), a reaction network of DBT HDS was proposed and the mechanisms of the cleavage of different C S bonds in DBT and its hydrogenated intermediates were discussed. CoP was much more active and more nitrogen-tolerant than Co 2 P, which make it a promising HDS catalyst. The HDS reactions over CoP and Co 2 P followed a pseudo-first-order kinetics and a pseudo-zero-order kinetics, respectively. Piperidine strongly inhibited the hydrogenation/dehydrogenation reactions and the direct desulfurization of DBT, but its inhibition on the desulfurization of TH-DBT and HH-DBT were less pronounced. The active surfaces of CoP and Co 2 P in HDS reactions can be cobalt phosphosulfide phases.
研究领域:
催化化学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2022
·Vol. 12
·期 8
·926
·
IF 4.501
Chunling Wu,Linge Ma,Yufei Zhu,Xuqiang Guo,Yongli Wu,Zhen Wu,Xian Zhang,Lihua Hou
In this paper, the extraction residue of direct coal liquefaction residue-DCLR(ER)was used as raw material. The high-temperature reaction mechanism of Mo compound in DCLR(ER)was investigated using a synchronous thermal analyzer and the Factsage database. The high temperature reaction of DCLR(ER)-MoO3in an oxygen atmosphere consists of pyrolysis of organic components at 400–600 °C, molybdenum trioxide sublimation at 747–1200 °C, and a stable stage at 600–747 °C. The thermal reaction process of the DCLR(ER)-MoS2system in the oxygen atmosphere involves the pyrolysis of unreacted coal and asphaltene, the oxidation of molybdenum sulfide at 349–606/666 °C, the diffusion of MoO3at 606/666–85 °C, and the sublimation reaction process of MoO3at 854–1200 °C. The results show that the lower heating rate can promote the oxidation of the Mo compound and the sublimation of molybdenum trioxide. On the other hand, the oxides of aluminum, calcium, and iron in DCLR(ER)can inhibit the oxidative pyrolysis efficiency of the DCLR(ER)-MoS2system.Keywords:direct coal liquefaction residue;molybdenum;high temperature;reaction mechanism
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2015
·
IF 3
Changxin Li,Hong Zhong,Shuai Wang,Jianrong Xue,Haibo Wang
In this study, using coal as a reducer, the thermal decomposition of CaSO 3 to produce CaS was carried out at different conditions. The mineralogical composition and microstructure of the as-obtained CaS were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results revealed that single-phase CaS was detected in the product under optimum conditions and the optimal synthesis conditions of CaS were as follows: molar ratio of C and CaSO 3 (C/S ratio)=2.5, reaction temperature 1173 K, reaction time 1.5 h and coal particle size 100 mesh. Under the optimum conditions, the purity and yield of CaS are up to 99.15% and 96.52% respectively, which indicated that the decomposition was almost complete and the as-synthesized CaS can be recycled to be a raw material in chemical industry. Meanwhile, thermodynamic calculation showed that the reaction for CaS generation was very complex and CaS was generated mainly through solid–solid reaction and gas–solid reaction.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
·
2023
·
IF 6
Hongyan Wang,Yurou Zhou,Jingpei Cao,Bofeng Zhang,Yajie Tian,Guozhu Liu
Adamantane derivatives, as promising high-density fuels, have been widely concerned in fields of volume-limited aerospace vehicles due to high density, heat of combustion and thermal oxidation stability. To reveal insights into their high-temperature decomposition behaviors, an experimental and theoretical investigation of adamantane (A) and 1-methyl adamantane (1-MA) pyrolysis was performed in a flow tube reactor at atmospheric to high pressure. Over twenty species were detected and identified, including C1-C5 light hydrocarbons, C5-C7 cyclic olefins as well as C6-C12 aromatics. The favorable decomposition channels of A and 1-MA are proposed and the effects of fuel structure characteristics and pressures on product formation behaviors are revealed. For the primary decomposition of A and 1-MA, the contributions of reaction types exhibit the obvious dependence on the pressures and temperatures, involving the unimolecular C-C dissociations by ring-opening, CH 3 -elimination as well as H-abstractions by H and CH 3 attacking. Considering methyl-substitution weakens dissociation energies of C-C and C-H bonds and leads more H-abstraction sites, 1-MA shows a higher pyrolysis reactivity than A. The effects of structure characteristics are also embodied in the formation of newly chain-branched unsaturated species and the concentrations of common small hydrocarbons and aromatics. Compared to A decomposition, the methyl substituent in 1-MA promotes the emergence of 1-butene, 2-methyl-1-butene, mesitylene, methylindane and methylnaphthalene, and increases the concentrations of methane, 2-methylpropene and xylene isomers, formed via β-scission, hydrogen transfer, isomerization and dehydrogenation routes of fuel radicals. Meanwhile, more methyl-substitutions accelerate the decomposition of alkyl-adamantanes and pyrolysis activity follows by a sequence of dimethyl-adamantane > methyl-adamantane > adamantane, boosting the production of methyl-specific species.
研究领域:
化学动力学
·
燃料化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Siyan Yan,Jiale Zhu,Jianguo Zhuang,Xinhui Liu,Yitao Zhao,Yuan Qian,Xuedong Zhu,Fan Yang
ZSM-23 zeolite with a reduced a -axis is synthesized using trimethoxy[3-(phenylamino)propyl]silane (TPPS) and applied in n -hexane cracking. Once nuclei are formed, TPPS primarily attaches to the ends of rod-like ZSM-23 crystals, effectively hindering elongation growth and significantly promoting the diffusivity of ZSM-23 zeolite. The carbonium pathway is favored over the carbenium pathway in n -hexane cracking when reduced a -axis ZSM-23 is applied, leading to higher ethene yield instead of propene. The fast diffusion also shifts deactivation from an inside-out process to an outside-in one due to the different precursors for carbon deposition. The obtained short a -axis ZSM-23 exhibits excellent catalytic performances in n -hexane cracking, displaying better activity (98.4% vs. 86.4%) and greater stability (2400 min vs. 120 min) than traditional ZSM-23. These findings deepen the understanding of organosilane’s role in unidimensional zeolite synthesis and unveil the structure-performance relationship and deactivation mechanism in n -hexane cracking.
研究领域:
材料科学
·
催化化学
·
化学工程
·
纳米技术
·
无机化学
✓ 已验证
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2024
·
IF 5.8
Sihao Yin,Yirou Du,Wuhua Lv,Yang Jiang,Dong Feng,Yuhui Xie,Delong Xie,Yi Mei
Black phosphorus nanosheets (BPns) have gained widespread attention in the field of flame retardancy due to their highly efficient flame-retardant properties achieved with a low addition rate (e.g., 0.4%). However, the pyrolysis pathways of BP in polymers have not yet been elucidated. This work systematically studies the flame retardancy and pyrolysis behavior of BP in oxygen-containing (polyurethane, PU) and oxygen-free (polypropylene, PP) polymers, distinguishing between the gas-phase and the condensed-phase flame retardant effect of BP. Through slow heating and staged heating methods, the condensed phase and gas phase pyrolysis products of BP in PU and PP at different temperatures are compared in detail. The distinct flame retardant pathways of BP in PU and PP are revealed. The results indicate that the oxidation of BP commences with its reaction with atmospheric oxygen, implying that the condensed-phase flame-retardant effect of BP primarily occurs at the polymer surface. In PP, BP mainly functions as a gas-phase flame retardant. In the condensed phase, BP generates phosphate derivatives that cover the substrate surface, providing solely a physical barrier effect. In PU, while BP demonstrates an outstanding gas-phase flame-retardant effect, it also accelerates the early dehydration carbonization of alcohols within the substrate, resulting in the formation of phosphate ester compounds (P–O–C structure) to bolster the thermal stability of residual carbon. Additionally, the side reactions of BP during catalytic carbonization will decrease the thermal stability of ester bonds in PU. This work lays a theoretical foundation for the development and application of BP-based flame retardant systems.
研究领域:
材料科学
·
燃烧学
✓ 已验证
产品关联
DOI
高影响因子
ChemistryOpen
·
2020
·Vol. 9
·期 10
·996-1000
·
IF 2.37
Fangjun He,Rumeng Qu,Jie Su,Muyao Du,Junqiang Liu,Yiping Chen,Bo Wang
Graphical Solving the puzzle : The role of the amine in direct amidation of aromatic ketones has been investigated. Amines act as both the reactant and catalyst, as such the excess amount (two or more equivalents) of amines are required to afford reasonable conversions/yields in the classical amidation. The direct amidation of aromatic ketones has been achieved at mild reaction conditions. In the classical amidation between aromatic ketones and amines, 2.0 equivalents of amines are necessarily required to gain satisfying yields. The specific role of the amine in the direct amidation already puzzled us for a long time. In this work, we disclosed that the amine acts as both reactant and catalyst. Specifically, the determination of reaction intermediates revealed the full mechanism, based on which, the introduction of one equivalent base in the amidation is showcased here that a high yield (∼95 %) can be afforded using only 1.1 equiv. of amine.
研究领域:
有机化学
·
催化化学
✓ 已验证
DOI
PubMed
高影响因子
ACS Omega
·
2024
·
IF 3.7
Shulei Shi,Xiao-Han Wang,Bingyou Jiang,Wenhan Tao,Chang-Fei Yu,Ben Ji
The natural material pectin was used as the matrix to prepare a dust suppressant. The regression model in response to the grafting ratio was established, and the optimum modification scheme was determined. The amount of monomer, initiator, cross-linking agent, and reaction temperature was 3.20 g, 0.20 g, and 0.15 g and 92 °C, respectively. Through Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy tests, not only the formation of the product in graft copolymerization reaction was validated but also the wettability of pectin was significantly improved. The surface morphology of pectin before and after modification was observed by a scanning electron microscope. After graft copolymerization treatment, the surface of pectin presented a dense grid structure, which proved that the pectin-modified dust suppressant can play a crucial role in wetting and condensing coal dust. Contact angle tests were used to characterize the effect of pectin modification on the wettability of bituminous coal before and after modification. The results of contact angle tests showed that when the droplets just contacted the bituminous coal flakes, the contact angle of modified pectin droplets on the flakes was the smallest, and the value was 55.21°. Compared with pure water droplets and unmodified pectin droplets, it decreased by 21.66° and 18.50°. The modification reaction process and dust suppression mechanism were explained at the molecular level.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）