JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
·
2015
·
IF 3.615
Jian Wang,Xue Wang,Xiaolong Liu,Junlin Zeng,Yangyang Guo,Tingyu Zhu
In this article, we present a detailed study combining the kinetic studies and in-situ FTIR experiments to investigate the oxidation behavior of chlorobenzene over V 2 O 5 /TiO 2 catalysts. The catalytic data show the 3–5 wt.% V 2 O 5 /TiO 2 catalysts are best fit for the oxidation of chlorobenzene. The calculated apparent reaction orders are about 0.6 and 0.2, respectively. The results of in-situ FTIR provided mechanism insights into the catalytic reaction, which supports the following proposal: (i) a nucleophilic substitution on V O species and (ii) attacking by surface oxygen through a electrophilic substitution, then (iii) followed by the cracking of ring structure, and further oxidation of the resulting species to form final products. The above results further suggest that the nucleophilic substitution process and surface reaction are kinetically significant steps for chlorobenzene oxidation, determining the overall rate of the reaction. Furthermore, 1,2-dichlorobenzene, 1,3-dichlorobenzene and 1,2,4-trichlorobenzene as additional reactants were tested together with chlorobenzene in binary mixtures to examine their competition reactions.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Catalysts
·
2022
·Vol. 12
·期 12
·1562
·
IF 4.501
Di Liu,Hui-Zi Huang,Zhejiaji Zhu,Jiani Li,Li-Wei Chen,Xiao-Ting Jing,An-Xiang Yin
The development and commercialization of direct ethanol fuel cells requires active and durable electro-catalysts towards the ethanol oxidation reactions (EOR). Rational composition and morphology control of Pt-based alloy nanocrystals can not only enhance their EOR reactivity but also reduce the consumption of precious Pt. Herein, PtCu nanocubes (NCs)/CB enclosed by well-defined (100) facets were prepared by solution synthesis, exhibiting much higher mass activity (4.96 A mgPt−1) than PtCu nanoparticles (NPs)/CB with irregular shapes (3.26 A mgPt−1) and commercial Pt/C (1.67 A mgPt−1). CO stripping and in situ Fourier transform infrared spectroscopy (FTIR) experiments indicate that the alloying of Cu enhanced the adsorption of ethanol, accelerated the subsequent oxidation of intermediate species, and increased the resistance to CO poisoning of PtCu NCs/CB, as compared with commercial Pt/C. Therefore, alloying Pt with earth-abundant Cu under rational composition and surface control can optimize its surface and electronic structures and represents a promising strategy to promote the performance of electro-catalysts while reduce the use of precious metals.Keywords:Pt–Cu alloy;nanocubes;electrocatalysis;ethanol oxidation reaction;in situ FTIR
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
Nanoscale
·
2020
·Vol. 12
·期 25
·13688-13696
·
IF 6.895
Ping Li,Cheng Du,Xiaohui Gao,Zhihua Zhuang,Dong Xiang,Chunmei Zhang,Wei Chen
Morphology modulation and surface structure-controlled synthesis are two effective ways to tune the electrocatalytic activities of metal nanomaterials. Pt-based binary or ternary metal nanostructures have become a class of promising catalysts toward the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) for direct methanol fuel cells. Herein to reveal the morphology and surface structure effects of one-dimensional (1D) Pt-based nanostructures on their electrocatalytic properties, two types of 1D CuPt nanowires (CuPt NWs) and CuPt nanotubes (CuPt NTs) with tunable surface structures and compositions were fabricated using a convenient and easy strategy. It was found that among all the studied samples, CuPt2.22 NWs exhibited the highest efficiency catalytic performances for both the ORR and MOR in an acidic electrolyte. For the ORR, CuPt2.22 NWs exhibited an onset potential (Eonset) of 0.749 V and a half-wave potential (E1/2) of 0.577 V, which are more positive than those of the commercial Pt/C (0.668 V and 0.558 V). On the other hand, CuPt2.22 NWs show a specific activity of 20.76 mA cm−2 and a mass activity of 0.171 mA μgPt−1 for the MOR, which are 7.75 and 1.82 times, respectively, larger than those of Pt/C (2.679 mA cm−2 and 0.094 mA μgPt−1). Meanwhile, the reaction mechanism of the MOR on CuPt2.22 NWs was examined by in situ FTIR. From the enhanced IR absorption, the linear- and bridge-adsorbed CO intermediates can be determined during the methanol oxidation on CuPt2.22 NWs, from which the MOR proceeds through a dual reaction pathway. This work reveals that rationally tuning the electronic structures of 1D metal nanomaterials by well-controlling the composition and surface morphology on the nanoscale could greatly enhance the catalytic properties, which are very important for their application in fuel cells.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysts
·
2022
·Vol. 12
·期 11
·1296
·
IF 4.501
Ruiqin Ding,Guangying Fu,Songxia Wang,Yang Yang,Qiaolin Lang,Haonuan Zhao,Xiaobo Yang,Valentin Valtchev
Narrowly dispersed ultrafine Cu clusters of sizes smaller than 2.0 nm have been encapsulated in nanosized silicalite-1 zeolite through direct crystallization in the presence of Cu(en)22+complex ions as the metal precursor. The growing silicalite-1 crystals are rich in vacancy defects and connectivity defects on the grain boundaries, where the terminating silanols promote the decomposition of Cu(en)22+, thus the deposition of ultrafine Cu species. The obtained composite material as a model catalyst is active for CO2activation and hydrogenation to methanol. The preliminary in situ FTIR study recognizes a series of surface-adsorbed carbonyl, formyl, carbonate, and formate species when the material is exposed to CO2and H2. Among others, the adsorbed formate decays most rapidly upon cofeeding CO2and H2, implying that the most probable pathway toward methanol formation over this material is via the formate-mediated mechanism.Keywords:CO2to methanol;direct crystallization of Cu@nano-zeolite;ultrafine Cu cluster;in situ FTIR;reaction intermediates
研究领域:
催化化学
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材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yuhang He,Hua Ke,Yangcheng Lu
Controlled alcoholysis of ethylene–vinyl acetate copolymer (EVA) is very important both to industry and academic research. To this end, accurate kinetic model is an important tool, but traditional methods for studying reaction kinetics involving polymers are usually laborious and time consuming due to the need of product purification. Therefore, we developed a new method to study the alcoholysis of EVA with 32 mol% ethylene content based on in situ FTIR spectroscopy. The feasibility and accuracy of this method was carefully studied. A kinetic model for predicting reaction rate was obtained using this method. The applicability of the kinetic model was further verified by performing flow alcoholysis in microflow reactor. It was found that this kinetic model is pretty accurate for conversions up to around 60 %, even at a relatively high temperature. The in situ FTIR method may also be suitable for monitoring industrial production process and other alcoholysis systems like PVA.
研究领域:
高分子化学
·
化工工程
·
分析化学
✓ 已验证
DOI
高影响因子
ChemElectroChem
·
2023
·Vol. 10
·期 10
·e202300023
·
IF 4
Xuebing Xu,Yang Song,Chaoquan Hu,Mingyuan Shao,Chang Li
Graphical Ultrathin nanosheets for high-performance asymmetric supercapacitors : Uniform ultrathin hexagonal nanosheets of Co 0.32 Ni 0.68 (OH) 2 is designed and synthesized. It exhibits 12 times higher of specific capacity than Co(OH) 2 . In situ FTIR and DFT calculations confirm the inherent interaction. The assembled Co 0.32 Ni 0.68 (OH) 2 //AC ASC delivers superior performance with a high energy density of 54.97 W h/kg at a power density of 1.68 kW/kg and maintains 33.52 W h/kg at 32.66 kW/kg. In this work, uniform ultrathin hexagonal nanosheets of Co−Ni bimetallic hydroxides are synthesized using a simple green hydrothermal synthesis method. By tuning a Co/Ni mole ratio of 1 : 2, a special nanosheet structure of Co 0.32 Ni 0.68 (OH) 2 was obtained with high interlayer spacing and large pore size. This nanosheet exhibits an enhanced specific capacity as high as 1021.96 C/g at 0.5 A/g, 12 times higher than Co(OH) 2 (83.23 C/g). The high electrochemical performance is attributed to the interfacial interaction between Co 2+ and Ni 2+ , as well as its special nanosheet structure. The advantages of the composition and structure are further confirmed by density functional theory (DFT) calculations. Besides, the energy storage process was visually observed by in situ Fourier transform infrared (FTIR) spectroscopy. Furthermore, an asymmetric supercapacitor (ASC) is assembled by Co 0.32 Ni 0.68 (OH) 2 and activated carbon electrodes. The ASC delivers a high energy density of 54.97 W h/kg at a power density of 1.68 kW/kg and maintains 33.52 W h/kg at 32.66 kW/kg. These results highlight the promising applications of ultrathin Co 0.32 Ni 0.68 (OH) 2 nanosheets as a high-performance electrode material in supercapacitors.
研究领域:
材料科学
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电化学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
VIBRATIONAL SPECTROSCOPY
·
2023
·
IF 2.5
Liwei Ni,Shiying Yang,Wenze Qiu,Jialei Jin,Qiyue Xu,Shuliang Ye
The reaction pathway of many Paal-Knorr reactions for pyrrolic compounds hasn’t been thoroughly studied and remains controversial. In this work, the synthesis of an important anti-ultraviolet agent N-butoxycarbonyl-2,5-dimethylpyrrole based on the Paal-Knorr reaction was studied via in-situ Fourier transform infrared (FTIR) analysis combined with density functional theory (DFT) calculation. The online spectral data were analyzed using K-means clustering in order to find the characteristic wavenumbers of intermediates. It was found that the reaction with 2,5-hexadione and butyl carbamate are more favorable to form the imine and enamine intermediates by nucleophilic addition, which is different from another Paal-Knorr reaction with 2, 5-hexadione and ethanolamine . In addition, the reaction kinetic model was established through chemometric methods, with parameters of two rate-limiting reaction steps calculated. This approach of FTIR analysis is proven to be an effective tool for mechanism study of organic synthesis.
研究领域:
有机化学
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Zhongchun Yuan,Tingting Cao,Min Deng,Jun Ma,Shuo Geng,Chunliang Yang,Yuan Ren,Mengqin Yao,Fei Liu,Xiaodan Wang
It is very crucial but still a huge challenge to develop efficient and durable catalysts to promote hydrogen production from formic acid (FA). Herein, three CeO 2 with structurally well-defined different shapes, i.e., sCeO 2 (spheres), rCeO 2 (rod) and oCeO 2 (octahedral), are prepared, and their effect on the crystal faces and oxygen vacancy over the constructed heterostructure catalysts (Pd-CeO 2 /C) have been intensively investigated in the FA dehydrogenation. Pd-sCeO 2 /C outperforms the other catalysts with a turnover frequency (TOF) value of 2691 h −1 and selectivity to hydrogen of 100 % at 30 °C. A synergism between the CeO 2 (1 1 0) facet and more oxygen vacancies is considered to be key to obtaining the high reactivity. Moreover, biomass carbon promotes the dispersion of Pd-CeO 2 heterostructures due to its large specific surface area and causes more defects in the Pd-CeO 2 /C. Combined with in-situ FTIR and density functional theory (DFT), it is speculated that FA is decomposed through formate pathway over the Pd-sCeO 2 /C. This work thus provides a reasonable design and controllable synthesis strategy for the effective application of FA as an available liquid phase hydrogen storage material.
研究领域:
催化
·
材料科学
·
化学工程
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Tiping Wei,Liguo Wang,Jiajun Zhang,Yan Cao,Xiang Hui,Jianhui Shi,Shuang Xu,Liyan Zhao,Peng He,Huiquan Li
Bio-based pentamethylene dicarbamate (PDC) belongs to N-substituted carbamates, which are important fine chemicals and organic intermediates. In this work, well-defined CeO2 rods, cubes, and octahedrons were successfully prepared to catalyze the synthesis of PDC by carbonylation of 1,5-pentanediamine (PDA) with methyl carbamate (MC). Among them, CeO2 rods with higher amounts of acid–base sites and abundant oxygen vacancies showed superior intrinsic activity in the PDA carbonylation reaction. In situ FTIR results showed that intermediate polyureas were readily formed in the reaction, and then, CeO2 rods promoted the alcoholysis of polyureas to PDC. In situ DRIFTS results indicated that the surface of CeO2 rods is more favorable for the adsorption and activation of the reactants. CeO2 rods can also be used for the efficient synthesis of a series of N-substituted carbamates. We believe that this work will contribute to the efficient, green, and sustainable production of N-substituted carbamates.
研究领域:
催化
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化学工程
·
绿色化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Yan Huang,Yufeng Zhou,Zebin Yu,Shijie Li,Zuofang Yao,Yi Liu,Xinqiu Tan,Yikai Wang,Yanping Hou
To address the bottlenecks of sluggish carrie r separation and insufficient active sites in lead-free halide perovskite of Cs 3 Sb 2 Cl 9 , magnetic transition metal (Co) was introduced and regulated the Co/Sb bimetallic ratio via a facile co-precipitation method to develop the Cs 4 Co 1.2 Sb 1.8 Cl 12 for light-driven CO 2 conversion. Results of electron paramagnetic resonance (EPR), Kelvin probe force microscopy (KPFM) and theoretical calculations revealed that the introduction of Co 2 + could promote the formation of chlorine vacancies ( V Cl ) and enhance local spin polarization, thereby facilitating CO 2 adsorption and activation, as well as accelerating carriers separation. The average carriers lifetime of the Cs 4 Co 1.2 Sb 1.8 Cl 12 was 1.8 times that of pristine Cs 4 CoSb 2 Cl 12 , beneficial to charges participation in CO 2 reduction reaction. The CO yield from the Cs 4 Co 1.2 Sb 1.8 Cl 12 (130.23 μmol·g −1 ·h −1 ) was 1.33 times that of Cs 4 CoSb 2 Cl 12 and 278 times that of pur e Cs 3 Sb 2 Cl 9 . Notably, without sacrificial agent, an unprecedented CO yield of 66.22 μmol·g −1 ·h −1 was achieved in photocatalytic CO 2 reduction, representing the best performance among lead-free halide double perovskites reported to date. In-situ FTIR analysis demonstrated the carboxylate (COOH*) as the dominated intermediate during CO 2 reduction. This work provides a reference for designing efficient lead-free halide perovskite photocatalysts via enriching halide vacancies and strengthening spin polarization for CO 2 conversion.
研究领域:
材料科学
·
光催化
·
钙钛矿化学
·
环境科学
·
能量转换
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2022
·
IF 8.047
Leisheng Che,Jinqiu Guo,Zhiwei He,Hongbo Zhang
We report here that the reduction degree of the metal at the catalytic interface dominates the reactivity of acetylene hydrogenation, mainly in terms of turnover rates (TORs) and activation energies, which could certainly cause the switch of kinetically relevant steps (KRS) from “C 2 H 3 *+H*” over Ce(OH)SO 4 ·xH 2 O dispersed Pd catalyst to “C 2 H 4 *+H*” elementary step over Pd/CeO 2 . Besides, a compact kinetic model has been established to describe the reaction process and the dissociative mechanism was confirmed by H 2 /D 2 exchange experiment. Meanwhile, the rate-determining step (RDS) and the main adsorbed species of the reaction were confirmed by systematic kinetic studies as well as in-situ FTIR analysis. More importantly, with the aid of parity fitting and gas isothermic adsorption analysis, the energetic relationship among the steps along with the acetylene hydrogenation is quantitatively described, which provides a good support and complement for the previous research, and helps researchers build up advanced reaction systems.
研究领域:
化学动力学
·
催化
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2022
·Vol. 25
·期 2
·596-605
·
IF 11.034
Haitao Yu,Yimin Xuan,Qibin Zhu,Sheng Chang
It is extraordinarily exigent to solve the efficiency of 6H+/6e− photoreduction of CO2 and H2O into methanol as the major product, which is limited by the severe photogenerated carrier recombination, the reoxidation of methanol at high temperature, and photocorrosion of catalysts. Herein, we developed an elaborate gas–liquid–solid system assembled by using a novel multicomponent SrTiO3 (La Cr)/Cu@Ni/SiO2/TiN (STO/Cu@Ni/SiO2/TiN) heterojunction, realizing a highly efficient and robust photocatalytic CO2 reduction to methanol at low temperature. STO/Cu@Ni/SiO2/TiN exhibits excellent light absorption and high charge carriers separation nature, and the evolution of methanol is 25.8 μmol (h gcat.)−1 roughly not only 173 folds higher than those observed compared with the STO counterpart, but also is 50 times that those of traditional gas–solid two-phase system. Of note, these improved performances are attributed to the enhancement of the local surface plasmonic resonance of Cu@Ni nanoparticles by changing the local medium dielectric constant and prolonged carrier's lifetime originating from heterostructure. Moreover, plasmonic TiN nanoparticles play an important role in remaining the triphase interfacial system temperature at 90 °C and increasing methanol production excellently. While, the ionic liquid in the gas–liquid–solid system can activate CO2 molecules, thereby greatly improves the yield of methanol. In situ Fourier transform infrared (FTIR) spectra and 13C isotope labeling tests reveal the reaction path of CO2 on the photocatalyst surface. This work may provide a new direction for the efficient photoreduction of CO2 to methanol.
研究领域:
化学
·
材料科学
·
环境科学
·
催化
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）