CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Shuo Li,Jianlin Cao,Xiang Feng,Yupeng Du,De Chen,Chaohe Yang,Wenhua Wang,Wanzhong Ren
Elucidating the confinement effect harbours tremendous significance for isobutane alkylation with C 4 olefin . Herein, the confinement effect over zeolite catalysts was elucidated by combining DFT calculations, experiments (using the novel Beta zeolite exposing only external surfaces (Beta-E) and conventional Beta-I zeolite with both external and internal surfaces) and multi-techniques ( e . g ., TGA-DTG, HRTEM, SEM and XRD). It is found that the main active sites for C 4 alkylation reaction are located on internal surface rather than external surface. On the external surface, the hydride transfer reaction does not occur because the H-shared intermediate cannot be formed without the confinement effect. Moreover, the external surface has stronger selectivity for C 4 olefin adsorption than isobutane, leading to enhanced oligomerization reactions. Therefore, the suitable micropore with confinement effect is essential for zeolite-catalyzed C 4 alkylation. The atomic-scale insights of this work are of great referential importance to the design of highly effective zeolite catalyst.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
·
2024
·
IF 4.3
Ling Pan,Song Ye,Ruihao Huang,Meiyan Wang,Tianning Zheng,Haoran Zhang,Deping Wang
Luminescent silver clusters that are confined inside porous zeolites have attracted great research interest due to the combined advantages of high quantum yield, tunable emission, excellent chemical stability, and desirable adoption ability of this micronano-composite. In this research, a series of Ag-exchanged R-LTA/Ag (R = Li, Na, K) zeolites were synthesized, in which the silver clusters showed blue-shifted excitation in the UV region, red-shifted emission in the visible region, and decreased emission intensity when taking Li+, Na+, and K+ as the extra-framework cations, respectively. The [Ag4(H2O)xR4-sod]6– (x = 2, 4; R = Li, Na, K) structures were constructed, and the TD-DFT method was further carried out to study the influence of extra-framework cations on the luminescence performance of [Ag4]2+ clusters, in which the substitution of Al for Si and the reasonable hydrate levels were both taken into consideration. It is estimated that the S1 and S3 levels for the [Ag4(H2O)4Li4-sod]6– cluster, the S4 level for the [Ag4(H2O)4Na4-sod]6– cluster, and the S5 level for the [Ag4(H2O)2K4-sod]6– cluster can be effectively populated through direct excitation, and the S1 → S0 transition is assumed to be responsible for the radiative emission in the visible region for the [Ag4]2+ pseudo-tetrahedrons. This calculated energy level diagram and simulated absorption spectra of [Ag4(H2O)xR4-sod]6– (x = 2, 4; R = Li, Na, K) clusters explained the modified luminescence property of silver clusters in R-LTA/Ag (R = Li, Na, K) zeolites studied in this research and reported literature.
研究领域:
材料科学
·
光物理学
·
理论化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Nano Materials
·
2024
·
IF 5.3
Peiwen Ju,Hui Zhong,Zhiguo He,Weiqi Xie
The catalytic production of aromatic azo compounds by aniline’s oxidative coupling process is significant in organic synthesis. However, the catalysts used in this method generally exhibit low selectivity for the desired products and need costly preparation methods. In this study, for the first time, we proposed a species regulation strategy to synthesize the Rb-doped Cu/CeO2 nanorod catalyst, which showed high conversion (98%) and selectivity (95%) toward oxidative coupling of aniline to azoxybenzene using H2O2 as the oxidant. Aniline radical ion trapping experiments demonstrated that the oxidative coupling of aniline to azoxybenzene follows a nitrosobenzene intermediate mechanism. Characterization studies revealed that the addition of Rb not only enhances the interaction between Cu species and CeO2 but also increases oxygen vacancy content. DFT calculations indicate that the Cu–Ce and Rb–Ce interfaces are the main active sites, offering excellent catalytic performance. The reusability test for five cycles shows good stability of a Rb–Cu/CeO2 nanorod catalyst. The study provides a promising species regulation strategy for Rb-promoted nanocatalysts with ultrahigh selectivity, expanding their applicability in oxidative coupling and related reactions.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2025
·
IF 9.5
Qiang Fu,Zhiling Huang,Zheming Ni,Shengjie Xia
Effectively enhancing nitrogen activation and inhibiting water splitting reactions are key factors in photocatalytic nitrogen reduction. This work integrated defect engineering and metal doping, doping transition metals Sc, Cu, and V into molybdenum sulfide (MoS2) containing sulfur vacancies (VS) to prepare TM@VS−MoS2(TM=Sc, Cu, V), applied for photocatalytic nitrogen reduction (pNRR). High angle annular dark field scanning transmission electron microscopy (HAADF-STEM) confirms the existence of S vacancies. The pNRR activity of Sc@VS−MoS2, Cu@VS−MoS2 and V@VS−MoS2 is 124.26 μmol g−1 h−1, 101.32 μmol g−1 h−1, 88.64 μmol g−1 h−1, respectively, which is much higher than that of MoS2, VS−MoS2, and TM@MoS2. This fully demonstrates that the comprehensive use of S vacancies and metal doping can significantly enhance the photocatalytic performance of MoS2 (with a maximum activity improvement of nearly 5 times). DFT calculations show that transition metal doping can further promote the activation of N2 and inhibit the production of H2 from water decomposition for vacancy MoS2. The effect of the above promotion and inhibition is consistent with the order of activity and photoelectronic properties: Sc@VS−MoS2>Cu@VS−MoS2>V@VS−MoS2. In situ infrared spectroscopy revealed the generation of −N2Hy (1≤y≤4) active species during the pNRR process, which is consistent with the most potential pathway (enzymatic mechanism) calculated by DFT.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Lingying Chen,Qinke Tang,Yichen Qi,Jiguang Zhang,Rui Shi,Yana Liu,Jun Wang,Yunfeng Zhu
Practical applications of magnesium hydride are hampered by high thermodynamic stability and slow kinetics. The design of highly active catalysts is essential to improve the kinetics of MgH 2 . Although studies concerned with the interaction between MgH 2 and catalyst have remained quite active, detailed investigation of the beneficial effect from the phase transformation is lacking. Herein, a high-activity VS 2 was designed and introduced to catalyze MgH 2 , and the MgH 2 -VS 2 system exhibited superior hydrogen desorption capabilities at comparatively low temperatures (3.5 wt% H 2 , 1800 s, 225 °C). This enhancement in the hydrogen storage performance of MgH 2 was attributed to the in-situ phase transformation of the catalytic species during hydrogen cycling. DFT calculations demonstrated the catalytic effect of VS 2 and in-situ formation of new species relative to MgH 2 . Our results provide a deeper insight into enhancing dehydrogenation mechanism on metal hydrides of the high-activity catalyst.
研究领域:
材料科学
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化学工程
·
催化
·
氢存储
✓ 已验证
DOI
高影响因子
Materials Today Energy
·
2019
·
IF 0
Jingwei Xiu,Yangfan Shao,Linxun Chen,Yue Feng,Junfeng Dai,Xusheng Zhang,Yi Lin,Yudong Zhu,Zhenggang Wu,Yini Zheng,Hui Pan,Chang Liu,Xingqiang Shi,Xin Cheng,Zhubing He
Owning the merits of both lead-free and air-stable, the double-perovskite Cs 2 AgBiBr 6 has attracted increasing attention, but suffers low visible-light absorption coefficient due to its large indirect bandgap. Moreover, the electronic structure of its synthesized films has not been explored clearly yet. In this work, we developed a general and promising method to fabricate continuous, uniform and highly orientated Cs 2 AgBiBr 6 films in large scale on various substrates through capillary-assisted dip-coating method. Strikingly, those optimized films are single crystalline verified by φ-scan XRD . Its electronic structure was carefully studied independently by multi-photo-physical characterizations. Its bandgap can be tuned from 2.65 to 2.25 eV by changing the substrate temperature in growth from 40 to 160 °C. Essentially, their work-function (WF) was determined at −5.01 eV and WF-VBM is around 2 eV. This novel band structure with typical n-type characteristic, was further confirmed by DFT calculations, which reveals that the Cs interstitials and Br vacancies derived deep defect levels were fixed around its Fermi level, closer to the conduction band. This conclusion is different from its widely accepted p-type feature, but definitely deepens our understanding of this material and inspires us to find more valuable strategies of modulating its band structure and optoelectronic properties.
研究领域:
材料科学
·
光电化学
✓ 已验证
DOI
Molecular Catalysis
·
2023
·
IF 4.6
Wujian Zhang,Weijian Ge,Yiping Jin,Mingming Dang,Panpan Zhang,Wenfeng Han,Ying Li,Zongjian Liu,Haodong Tang
Loaded noble metal redispersion is an important way to solve catalyst sintering. However, how to redisperse at low temperatures or carbon-based noble catalysts is a difficult problem. In this paper, we report this phenomenon occurring on PdCu alloy catalysts, where small-sized PdCu alloys can be realized from sintered large-sized PdCu alloys on carbon supports in a CO/O 2 atmosphere. The mechanism of redispersion is elucidated by XPS, TEM and DFT calculations. The main reason for the redispersion is the formation of the PdCuOx intermediate, which can easily migrate to the nearby catalyst surface and then be reduced to smaller PdCu alloy nanoparticles. This work provides a deeper understanding of the redispersion phenomenon and provides certain applications in industry.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 20
·12538-12546
·
IF 10.733
Wanhua Wang,Yi Yang,Daoming Huan,Likun Wang,Nai Shi,Yun Xie,Changrong Xia,Ranran Peng,Yalin Lu
Driven by the increasing global energy demand, the development of innovative energy conversion and storage systems is becoming more and more urgent. As one of the attractive means, water splitting has attracted widespread attention because of its great potential in storing electricity in the form of chemical fuel which also makes it a promising solution to the utilization of non-grid electricity generated by solar or wind. The oxygen evolution reaction (OER) is generally deemed as the key rate-limiting step of water splitting, and thus studying efficient OER electrocatalysts with a low overpotential and good stability is of vital importance. Here, we successfully prepared an OER catalyst with excellent electrochemical performance through a simple anion doping. Firstly, a stable cubic perovskite SrCoO3−δ was prepared by anion F-doping instead of traditional A and/or B site doping. Secondly, SrCoO2.85−δF0.15 demonstrates excellent OER activity superior to its parent hexagonal compound H-Sr2Co2O5 and those perovskites prepared via complicated A- and/or B-site doping. DFT calculations and XPS investigations reveal that the cubic structure and the highly oxidative oxygen species (O22−/O−) via F− doping jointly contribute to the better OER properties of SrCoO2.85−δF0.15. Our work brings forth a promising strategy to stabilize cubic structures from hexagonal ones via a simple anion doping strategy, which may open a new avenue for the development of even more effective OER catalysts and may be applied in many other fields related to structure transformation, in addition to energy and catalysis fields.
研究领域:
能源材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2013
·
IF 5.265
Wen-Juan Zhou,Raphael Wischert,Kai Xue,Yu-Ting Zheng,Belén Albela,Laurent Bonneviot,Jean-Marc Clacens,Floryan De Campo,Marc Pera-Titus,Peng Wu
Various types of Ti-containing zeolites, i.e., Ti-MWW, TS-1, Ti-MOR, and Ti-BEA, have been evaluated as candidates for the liquid-phase oxidation of cyclohexane using t-butyl hydroperoxide (TBHP, 7–8 wt %) as model oxidant. Ti-MWW zeolite displayed the highest activity for cyclohexanol and cyclohexanone (KA oil) with an overall selectivity higher than 90% at 80 °C, making this catalyst a candidate of choice for industrial KA oil production by deperoxidation of cyclohexyl hydroperoxide. The effect of the reaction temperature, reaction time, catalyst amount, and catalyst stability on Ti-MWW was surveyed in detail. The Ti-MWW catalyst showed a stable performance and could be recycled at least four times without detectable Ti leaching and loss of structural stability. The active sites for cyclohexane oxidation appeared to be located near external 12-ring cups in the Ti-MWW framework as suggested by a series of position-selective poisoning tests with tripropyl- and triphenylamine, impelling cyclohexane diffusion within the internal 10-ring channels. EPR experiments supported by DFT calculations suggested the coexistence of both Ti(IV)-OO• (peroxyl) and Ti(IV)-O• (oxyl) species generated through bimolecular pathways, implying simultaneously (SiO)3Ti(OOtBu) species and tBuOOH. The catalytic activity was strongly inhibited in the presence of alkenes, leading to the preferential formation of the epoxidation product with no detectable formation of radicals. Notably, this is the first time that oxyl species have been detected particularly with the help of DFT calculations. Predicted differences of g tensors between peroxyl and oxyl species at various hydration levels in the presence of cyclohexane were consistent with the EPR spectra.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Water
·
2023
·Vol. 15
·期 10
·1920
·
IF 3.4
Yishu Cai,Fan Chen,Lingfang Yang,Lin Deng,Zhou Shi
Nanoplastics have gradually become a concern due to the wide use of plastics. Nanoplastics in aqueous phase can be exposed to users through water supply networks and cannot be efficiently removed by conventional water treatment processes. This work studied the degradation of polystyrene nanoplastics (PS-NP) by two commonly used advanced oxidation systems: UV/NaClO and UV/peroxymonosulfate (PMS). Results showed that almost no turbidity was detected in the PS-NP solution (5.00 mg/L) after treated by both UV/NaClO and UV/PMS for 360 min, suggesting the excellent turbidity removal ability. Yet, scanning electron microscope (SEM) and total organic carbon (TOC) removal tests demonstrated that PS-NP could not be completely degraded by UV/NaClO. The mineralization rate using UV/NaClO was only 7.00% even when the NaClO concentration increased to 5.00 mM, and many PS-NP particles could still be observed in SEM images. By contrast, the mineralization rate reached 63.90% in the UV/PMS system under the identical experimental conditions, and no spherical particles appeared in the SEM results. Density functional theory (DFT) calculations revealed that the different reaction sites and energy barriers of SO4•−and•Cl on PS-NP resulted in the differences in mineralization rates and degradation intermediates. The degradation pathway of PS-NP by UV/NaClO and UV/PMS was proposed accordingly. Additionally, the intermediates toxicity evaluation by a luminescent bacteria test showed that the inhibition rate in the UV/NaClO system (2.97%) was not markedly different from that in the control group without any treatment (1.98%); while that in UV/PMS system increased sharply to 98.19%. This work demonstrated that UV/PMS was more effective in PS-NP degradation than UV/NaClO, and the chemical risks of degradation intermediates were non-negligible.Keywords:nanoplastics;polystyrene degradation;mechanisms;DFT calculation;toxicity assessment
研究领域:
环境科学
·
化学工程
·
毒理学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2021
·Vol. 11
·期 15
·5125-5134
·
IF 6.119
Yanke Yu,Xianfang Yi,Jiali Zhang,Zhaojian Tong,Changwei Chen,Mudi Ma,Chi He,Jinxiu Wang,Jinsheng Chen,Bingbing Chen
Non-vanadium-based catalysts with high SO2 tolerance are still interesting in selective catalytic reduction of NO by NH3 (NH3-SCR) and SO2 adsorption is the foremost step for the deactivation of catalysts. In order to alleviate the adsorption of SO2, we fabricated a series of rhenium (Re; without stable sulfate) supported TiO2 catalysts and studied their SO2 tolerance for the first time. Owing to suitable surface acidity and reducibility, ReOx/TiO2 catalysts exhibited satisfactory activity in a wide temperature range of 250–350 °C. As expected, experimental results and DFT calculations indicated that SO2 adsorption on ReOx/TiO2 catalysts was rather weak, thus the catalysts performed excellent SO2 tolerance in the NH3-SCR reaction. Moreover, in situ DRIFTS indicated that the NH3-SCR reaction on ReOx/TiO2 catalysts followed the Eley–Rideal mechanism and SO2 had little effect on the reaction mechanism. Our findings should provide new insights into the development of SCR catalysts with high SO2 tolerance.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2022
·
IF 24.319
Dong-Xue Liu,Yi-Tong Zhou,Yong-Fu Zhu,Ze-Yu Chen,Jun-Min Yan,Qing Jiang
Formic acid (FA), as a safe and renewable hydrogen storage material, attracts extensive attention. Herein, an efficient catalyst Au 0.35 Pd 0.5 Ir 0.15 nanoalloy supported on NH 2 -N-rGO has been successfully synthesized and applied for hydrogen generation from FA. It is found by density function theory (DFT) calculation that addition of Ir into AuPd alloy can change the initial adsorption configuration of HCOOH* and thus reduce the energy barrier of rate determining step (RDS) of FA dehydrogenation . As a result, Au 0.35 Pd 0.5 Ir 0.15 /NH 2 -N-rGO displays 100% conversion, 100% selectivity even after 150 days for FA dehydrogenation at 298 K, and the initial turnover frequency (TOF) can reach the recorded value (12781.2 h −1 ) without any additives. More interestingly, it is proved to be a universal method to design the effective catalysts for hydrogen generation from FA by the high activities of other tri-metallic alloys with addition of other high γ elements (such as Pt, Rh, and Ru).
研究领域:
化学
·
催化材料
·
理论计算
·
能源科学
✓ 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）