JOURNAL OF CATALYSIS
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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
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能源化学
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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
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材料科学
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产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
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2015
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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
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化学工程
✓ 已验证
DOI
高影响因子
ChemistryOpen
·
2020
·Vol. 9
·期 10
·996-1000
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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
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催化化学
✓ 已验证
DOI
PubMed
高影响因子
ACS Omega
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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
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环境科学
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产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2024
·
IF 20.2
Jiaqi Li,Mingfei Wang,Jiamin Qi,Xueqian Wang,Langlang Wang,Fei Wang,Kai Li,Yixing Ma,Ping Ning
Hydrogen cyanide (HCN), a common toxic and hazardous air pollutant in industrial exhaust, catalytic hydrolysis of HCN has been the focus of air pollution control research. In this study, a catalyst material (La-TiO 2 ) with high catalytic hydrolysis activity for HCN was obtained by loading La 2 O 3 on the TiO 2 surface, which could realize the complete conversion of HCN at 150 °C with high selectivity of NH 3 and CO 2 . The relevant characterization confirms that La 2 O 3 can be uniformly distributed on the TiO 2 , which can adjust the acid-base structure of the catalyst surface and induce the generation of multi-hydroxyl structures in TiO 2 . On this basis, the combination of in-situ technique and density functional theory (DFT) calculations confirmed that the loading of La 2 O 3 prompted the La-TiO 2 catalyst to activate H 2 O to generate surface hydroxyl groups (-OH), which further enriched the hydroxyl groups on TiO 2 and substantially improved the hydrolysis activity and NH 3 selectivity of the catalyst. And the study confirms that the hydroxyl-rich environment easy combine with the reaction intermediate (formic acid) to generate CO 2 and H 2 O, which accelerated the reaction rate, thus improving the conversion efficiency of HCN and lowering the catalytic conversion temperature. In addition, O 2 can continuously consume the remaining hydrogen atoms after the dissociation of H 2 O to generate hydroxyl groups again, thus effective enhancing catalyst stability. This study provides new theoretical support for the catalytic hydrolysis of HCN and new insights and ideas for the design and development of catalysts for the catalytic hydrolysis of HCN.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2016
·Vol. 7
·期 1
·213-221
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IF 5.287
Xiaolong Liu,Junlin Zeng,Wenbo Shi,Jian Wang,Tingyu Zhu,Yunfa Chen
In this work, ruthenium-based bimetallic catalysts of the formula Ru–5M/TiO2 (M = Mn, Co, Ce, Cu, Fe) were prepared and evaluated in benzene oxidation, and Ru–5Co/TiO2 exhibited the lowest complete oxidation temperature (220 °C), demonstrating Co3O4 as the best dopant. The influence of the Ru and Co contents on the catalytic activity was also studied, and 1 wt% Ru and 5 wt% Co3O4 were confirmed. Water vapor showed an inhibition effect on benzene oxidation at 210 °C, whereas the catalytic efficiency was barely influenced at a higher temperature (230 °C). STEM analyses revealed that Ru–Co bimetallic species showed similar distributions on the catalytic surface. Based on the correlation of the catalytic results with various characterization techniques, the synergistic effect between Ru and Co was well demonstrated, and a four-step transformation in the oxidation process was concluded. Besides, systematic in situ FTIR studies for benzene oxidation over Ru/TiO2, Co/TiO2, and Ru–5Co/TiO2 were conducted and compared, and many organic intermediates were observed in the in situ FTIR spectra. Accordingly, the reaction mechanism for benzene oxidation over the Ru–Co bimetallic catalyst was proposed.
研究领域:
环境化学
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催化科学
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有机污染物降解
✓ 已验证
DOI
高影响因子
Processes
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2021
·Vol. 9
·期 2
·400
·
IF 2.847
Xiaohua Cao,Jichang Lu,Yutong Zhao,Rui Tian,Wenjun Zhang,Dedong He,Yongming Luo
Praseodymium (Pr)-promoted MCM-41 catalyst was investigated for the catalytic decomposition of methyl mercaptan (CH3SH). Various characterization techniques, such as X-ray diffraction (XRD), N2adsorption–desorption, temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectrometer (XPS), were carried out to analyze the physicochemical properties of material. XPS characterization results showed that praseodymium was presented on the modified catalyst in the form of praseodymium oxide species, which can react with coke deposit to prolong the catalytic stability until 120 h. Meanwhile, the strong acid sites were proved to be the main active center over the 10% Pr/MCM-41 catalyst by NH3-TPD results during the catalytic elimination of methyl mercaptan. The possible reaction mechanism was proposed by analyzing the product distribution results. The final products were mainly small-molecule products, such as methane (CH4) and hydrogen sulfide (H2S). Dimethyl sulfide (CH3SCH3) was a reaction intermediate during the reaction. Therefore, this work contributes to the understanding of the reaction process of catalytic decomposition methyl mercaptan and the design of anti-carbon deposition catalysts.Keywords:rare earth;MCM-41;CH3SH decomposition;stability;reaction mechanism
研究领域:
催化化学
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材料科学
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DOI
高影响因子
RSC Advances
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2015
·Vol. 5
·期 25
·19048-19057
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IF 3.84
JiaQin Sun,Wei Wei,YaZhen Xu,JieHao Qu,XiangDong Liu,Takeshi Endo
Five commercially available amines: m-phenylenediamine (A1), m-xylylenediamine (A2), isophorone diamine (A3), trimethylhexamethylenediamine (A4), and 4,4′-diaminodiphenyl sulfone (A5), were examined as nucleophilic hardeners for bis-benzoxazine monomers based on aniline paired with bisphenol-A (BA-a) or bisphenol-F (BF-a). The reactivities and reaction mechanisms of their mixtures with BA-a were investigated using FTIR and NMR spectroscopy, DSC, and HPLC techniques. It was found that BA-a rapidly cured with the amines upon heating at 120 °C or 150 °C. The cure rate was similar to the amine/epoxy curing process in practical uses, and significantly faster than the ring-opening polymerization of bulk BA-a. The possible reaction mechanism was supported by the experimental results and includes three successive steps: (i) nucleophilic substitution at the carbon atom (O–C–N) in the oxazine ring by the amine, (ii) thermal decomposition of the resulting aminomethanaminium structure, and (iii) electrophilic addition of the newly formed iminium ion with the aromatic ring to form stable aminomethylphenol structures. These findings are helpful to improve the thermosetting resins in terms of their chemical structure, material properties, and processability.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2019
·
IF 7.723
Shunan Zhang,Xiaofang Liu,Zilong Shao,Hui Wang,Yuhan Sun
Direct CO 2 hydrogenation to ethanol is one of the promising and emerging routes for the transformation of CO 2 into value-added chemicals, but it remains a major challenge because of low ethanol selectivity and catalytic stability. In this work, Na-promoted cobalt catalysts supported on different materials (Al 2 O 3 , ZnO, AC, TiO 2 , SiO 2 , and Si 3 N 4 ) were evaluated to elucidate the effects of supports. The SiO 2 - and Si 3 N 4 -supported catalysts exhibited efficient generation of ethanol with 18% CO 2 conversion and 62% selectivity in the alcohol distribution at 250 °C, whereas CH 4 was predominantly produced on other supported catalysts. Characterization results indicated that the Co 2 C active phase only remained intact on SiO 2 and Si 3 N 4 supports during reaction and exhibited excellent durability for 300 h, which was attributed to the existence of a strong metal–support interaction (SMSI) obtained by Si O Co bond formation. In situ DRIFTS results revealed that CO produced on Co 2 C inserted into CH x intermediates to form ethanol. Moreover, CO as the reactive intermediate could induce the regeneration and reconstruction of decomposed Co 2 C on the surface for catalytic sustainability.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2020
·
IF 5.825
Junhui Liu,Guanghui Zhang,Xiao Jiang,Junhu Wang,Chunshan Song,Xinwen Guo
Iron-based catalysts have been widely used to synthesize value-added hydrocarbons through CO 2 hydrogenation. Fe carbide, Fe 5 C 2 , was proposed as the active phase responsible for C C coupling during the chain growth. However, the reaction mechanism over iron-based catalysts is still under debate due to the presence of multiple phases of Fe species. In this work, Fe 5 C 2 and K-modified Fe 5 C 2 were prepared and used to study the relationship between the Fe phase, catalytic performance and reaction pathways. CH 4 and CO selectivities of 46.1 C-mol% and 2.8 C-mol% were obtained on Fe 5 C 2 at a CO 2 conversion of 49.8 %, with the main hydrocarbon products being alkanes. With the addition of the promoter K, the C 2 -C 4 = selectivity increased to above 38.0 C-mol%, and the selectivity to C 5+ hydrocarbons increased to 23.9 C-mol% at a similar CO 2 conversion. CH 4 and C 2+ hydrocarbons formed through the CO 2 →CO→hydrocarbons (indirect) route over K-modified Fe 5 C 2 , whereas the direct hydrogenation route occurred on unmodified Fe 5 C 2 in addition to the indirect route of CO 2 to CO to hydrocarbons through Fischer-Tropsch synthesis (FTS) processes. This work offers insights in direct CO 2 hydrogenation over Fe 5 C 2 and Fe 3 O 4 -Fe 5 C 2 catalysts, which advances the understanding of the functions of active phases and reaction pathways of CO 2 hydrogenation over iron-based catalysts.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Huixin Zhou,Dingxun Ma,Lingwen Dai,Yichao Wang,Xiaoling Ren,Xiaozhen Liu,Xumin Li,Haijiao Xie,Xinqian Shu
Quartz (Qtz) and kaolinite (Kln) are the main siliceous minerals in coal gangue (CG), which can be converted into effective silica by mechanical activation and improve the utilization efficiency of CG in turn. This study aimed to analyze and reveal the reaction mechanism of siliceous minerals in CG under mechanical activation surface modification by experiments and DFT calculations. We showed that increasing the rotational speed and m(Al 2 O 3 /SiO 2 ) stoichiometric ratio simultaneously boosted the activation ratio of siliceous minerals, up to 3.91 %. Mechanical activation promoted the formation of oxygen vacancy structures on siliceous minerals surfaces, which aligned with the system’s activation capacity. The Exp3P2 polynomial function model best described the relationship between the rotational speed and the activation ratio of different siliceous minerals. The oxygen vacancy, S BET , rotational speed, milling temperature, m(Al 2 O 3 /SiO 2 ) stoichiometric ratio, total pore volume showed significant positive correlations with the activation ratio. First-principles calculations revealed that the oxygen defect formation energy of Kln (5.17 eV) was slightly smaller than Qtz (5.27 eV), Kln was more likely to form oxygen defects than Qtz in mechanically activated reaction. This research contributes to understanding the mechanical activation of CG into effective silica, enhancing its potential for the graded and quality-based utilization.
研究领域:
材料科学
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矿物加工工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）