Chemical Science
·
2021
·Vol. 12
·期 15
·5631-5637
·
IF 9.825
Qiujian Xie,Yumin Yang,Weijie Zhang,Zhu Gao,Xiaofeng Li,Juntao Tang,Chunyue Pan,Guipeng Yu
Conjugated microporous polymers (CMPs) are cost-effective photocatalysts in organic transformations, while they are usually limited by the insufficient separation of photogenerated charges. Here we report a polarization strategy through molecular geometry optimization to promote the charge separation of CMPs. Three CMP photocatalysts with an alternative donor–acceptor skeleton and tunable symmetry were synthesized by the oxidative coupling of bis-carbazoles with electron-deficient bridges (benzene/pyridine/pyrimidine). Simply regulating the polarization of the starting monomers leads to tailorable porosity, photoelectric properties, and photocatalytic activity of the CMPs. They exhibited high efficiency in C-3 selenocyanation of indoles under visible-light and at room temperature, and pyridine-based CMPs with the largest dipole moment gave a yield of up to 94%, superior to their state-of-the-art photocatalyst counterparts. Photo-physical experiments combined with theoretical calculations further supported that the incorporation of the polarized linker introduced an internal electric field, benefitting efficient charge separation. This offered new insight into developing high-performance photocatalysts.
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Catalysts
·
2023
·Vol. 13
·期 11
·1438
·
IF 3.9
Zhi Hu,Yiyi Cheng,Meng Wu,Ying Duan,Yanliang Yang,Tianliang Lu
An advanced strategy was developed for the synthesis of molecular sieve-supported Pd catalysts. In this method, reductant containing C=C was in-situ prepared and pre-dispersed in the pore of the zeolites. The C=C group in the reductant can reduce the Pd2+to Pd0efficiently, leading to the formation of small and uniform Pd nanoparticles (~2 nm). The physical and chemical properties of the catalyst were characterized by XRD, TEM, XPS (ICP-OES), N2isothermal adsorption-desorption, and H2-TPR. These catalysts showed high catalytic performance for the hydrogenation of nitrobenzene to aniline. All the TOFs for 1.5 Pd/Y, 1.5 Pd/ZSM-5, and 1.5 Pd/MOR with 1.5 wt% Pd loading are higher than 1000 h−1at 30 °C and 0.1 MPa H2. Meanwhile, kinetic analysis for 2.0 Pd/Y was carried out, and an apparent activation energy of 28.88 kJ mol−1was obtained, which is lower than most of the reported values in the literature. Furthermore, these catalysts were stable and recyclable.Keywords:Pd;in-situ reduction;hydrogenation;molecular sieve
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Reaction Kinetics Mechanisms and Catalysis
·
2023
·
IF 1.8
Luo Peng,Chen Junteng,Mu Manman
Herein, a series of cobalt nanoparticles embedded in nitrogen-doped porous carbon catalyst (Co@NPC) was prepared through the pyrolysis of tetragonal Co-based metal–organic framework which consisted of Co centers and benzimdazole linkers. Due to large BET specific surface area (389.41 m 2 /g), abundant metallic Co content (39.3%), small Co nanoparticle size and high pyridinic-N content, the as-obtained Co@NPC-700 catalyst exhibited superior catalytic performance for the hydrogenation and one-pot reductive acetylation of nitrobenzene. The high 99.80% conversion of nitrobenzene and 99.56% yield of aniline were acquired in the catalytic hydrogenation of nitrobenzene with hydrazine hydrate at 80 °C for 2 h. Simultaneously, the above catalyst showed high conversion (87.2%) and selectivity (95.3%) for the one-pot reductive acetylation of nitrobenzene in the presence of phenyl silane at room temperature. Additionally, Co@NPC-700 exhibited excellent activities for the catalytic hydrogenation and one-pot reductive acetylation of other nitroarenes as well as good recyclability. This work offered a facile approach to prepare metallic Co loaded on porous carbons, serving as efficient catalysts for catalytic reductive applications.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2023
·
IF 11.4
Dong Cheng,Yuansen Tan,Runhao Ma,Haoran Ding,Wenjuan Liao,Kai He,Rui Sun,Hengli Ni,Feng He
Mackinawite (FeS) has gained increasing interest due to its potential application in contaminant removal by either reduction or oxidation processes. This study further demonstrated the efficiency of FeS in degrading nitrobenzene (ArNO2) via a sequential two-step reduction and oxidation process under neutral conditions. In the reduction stage, FeS rapidly reduced ArNO2 to aniline (ArNH2), with nitrosobenzene (ArNO) and phenylhydroxylamine (ArNHOH) serving as the intermediates. X-ray photoelectron spectroscopy (XPS) analysis indicated that both Fe(II) and S(II) in FeS contributed electrons to the reduction of ArNO2. In the subsequent oxidation stage with oxygen, by addition of 0.5 mM tripolyphosphate (TPP), ArNH2 generated in the reduction process could be effectively oxidized to aminophenols by hydroxyl radicals (•OH), which would undergo eventual mineralization via ring-cleavage reactions. TPP exerted a favorable role in enhancing •OH production for ArNH2 degradation by promoting the formation of the dissolved Fe(II)-TPP complex, thus enhancing the homogeneous Fenton reaction. Additionally, TPP adsorption inhibited the surface oxidation reactivity of FeS due to the change of Fe(II) coordination. Finally, the effective degradation of ArNO2 by FeS in actual groundwater was demonstrated by using this sequential reduction and oxidation approach. These research findings provide a theoretical basis for a new FeS-based remediation approach, offering an alternative way for comprehensive removal of ArNO2.
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Nanoscale
·
2023
·Vol. 16
·期 1
·335-342
·
IF 6.7
Yinglei Liu,Chicheng Ma,Jiye Zhang,Huiying Zhou,Gaowu Qin,Song Li
The electronic interaction between a metal and a support modulates the electronic structures of supported metals and plays an important role in manipulating their catalytic performance. However, this interaction is mainly realized in heterogeneous catalysts composed of reducible oxides. Herein, we demonstrate the electronic interaction between γ-Al2O3 and η-Al2O3 with varying acid–base properties and supported Pd nanoparticles (NPs) of 2 nm in size. The strength and number of acid–base sites on the supports and catalysts were systemically characterized by FT-IR spectroscopy and TPD. The supported Pd NPs exhibit electron-rich surface properties by receiving electrons from the electron-donating basic sites on γ-Al2O3, which are beneficial for catalyzing the hydrogenation of nitrobenzene. In contrast, Pd NPs loaded on η-Al2O3 are electron-deficient because of the rich electron-withdrawing acid sites of η-Al2O3. As a result, Pd/η-Al2O3 exhibits higher catalytic activity in phenylacetylene hydrogenation than Pd/γ-Al2O3. Our results suggest a promising route for designing high-performance catalysts by adjusting the acid–base properties of Al2O3 supports to maneuver the electronic structures of metals.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Le Zhang,Ting Liu,Meng Zhu,Yong Liu
Persulfate (PS)-based advanced oxidation processes (SR-AOPs) is a promising approach for the removal of ammonia nitrogen (NH 3 -N) from wastewater, but it suffered from the low removal efficiency and the excessive oxidation of NH 3 -N to nitrate (NO 3 − ) or nitrite (NO 2 − ) in the absence of in-situ generated chlorine radicals. Therefore, it is still a challenge to improve the efficiency of NH 3 -N removal and the selectivity of NH 3 -N oxidation products towards dinitrogen (N 2 ) by SR-AOPs without chlorine radicals. Herein, a novel photo-assisted activation of SR-AOPs involving sodium silicate (Na 2 SiO 3 ) and sodium sulfite (Na 2 SO 3 ) was developed for NH 3 -N removal from wastewater. In this system, Na 2 SiO 3 was acted as a green buffer to maintain NH 3 -N in the form of un-ionized ammonia (NH 3 ) with strong reducibility, promoting the efficiency of NH 3 -N removal as well as ensuring the neutral effluent by receiving the H + from PS activation. Na 2 SO 3 could inhibit the excessive oxidation of NH 3 -N by regulating the redox potential of the solution and generating hydrated electrons (e aq − ) under light ( hv) irradiation, enhancing the selectivity of NH 3 -N oxidation products towards N 2 . 100 % of NH 3 -N removal efficiency and more than 98 % of N 2 selectivity were obtained after 30 min at the initial pH of 3–9 and the initial NH 3 -N concentration of 30 mg N/L. Based on the quenching experiment, EPR test and probe experiment, the HO and SO 4 − were the main reactive oxygen species (ROS) to be responsible for NH 3 -N oxidation. This study proposed a new approach for treatment of wastewater containing NH 3 -N by SR-AOPs.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Meiling Chen,Lei Zhou,Xiuqin Xiong,Shijun Zhu,Xinkai Yuan,Boyin Yan,Bingrui Ma,Jiachuang Shao,Liming Yang,Xubiao Luo,Penghui Shao
Conventional advanced oxidation processes were used to treat heavy metal complexes. However, a considerable amount of oxidants was required to enable effective oxidative degradation, which led to a significant increase of the treatment costs and subsequent difficulties in the sludge disposal. Based on the abundance of anions in heavy metal wastewater, the effects of anions on the in-situ degradation of Ni-EDTA in an oxidant-free electrochemical system with boron-doped diamond (BDD) as the anode were investigated. The presence of Cl - was found to exert a significant effect on improving the degradation process. Moreover, pH had little effect on the removal of nickel (Ni) and Ni-EDTA within a specific pH range (1 < pH < 9). The removal efficiencies of Ni and TOC reached 100 % and 77.45 %, respectively, at pH 2.16 with 0.4 M NaCl electrolyte, 2 mM Ni-EDTA concentration, and a current density of 50 mA/cm 2 . •OH and Cl• played crucial roles in the removal of Ni-EDTA by disrupting the chelation sites of Ni and EDTA molecules. The released Ni 2+ ions could active the H 2 O 2 in-situ generated at the cathode to produce •OH. The formation of the precipitation products such as NiOOH, Ni(OH) 2 , and NiCO 3 in the Cl - /BDD system were conform based on the XRD and XPS analyses, which suggested the possible pathways for the removal of Ni 2+ and Ni 3+ . Finally, the possible degradation pathways of Ni-EDTA were proposed based on the identification of intermediate products using UPLC-MS.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2023
·
IF 4.4
Xiangfen Xue,Mingjie Wei,Jing Yuan,Xinyu Huang,Qinghua Cao,Changkun Xia,Xiangheng Niu,Xiulian Yin
A convenient, fast, low-cost detection and discrimination method is demanded for environmental monitoring but still it remains more technological challenges. Herein, we demonstrate that the inner filter effect (IFE), in combination with three-dimensional fluorescence spectroscopy, can offer a virtual sensor array (VSA) as a proper solution. And with the aid of pattern recognition techniques, it is feasible to recognize compounds with structural similarities economically and effectively. In this study, with the help of visual clustering plots of principal component analysis (PCA), a prediction model based on hierarchical strategy was made using support vector machine (SVM) method for the qualitative profiling of aromatic pollutants. The VSA was constructed by a single metal–organic framework (MOF) recognition unit (MOF-74 (Zn)) with the excitation wavelength as external regulatory factors. Pattern characteristics of four aromatics with very similar structures (phenylamine, chlorobenzene, nitrobenzene, and phenol), both single analyte and binary mixtures, were acquired. The primary constituents of multi-dimensional spectral signals were subsequently extracted and fed into a vector machine to construct a prediction model through 10-fold cross-validation optimization, resulting in a classification accuracy of 100% for single analytes and 96% for mixtures. Quantitative research has shown that, except for chlorobenzene, all three other analytes can be predicted in concentration within an acceptable error range, and the mixture can be predicted proportionally. Moreover, the VSA can be used to distinguish these pollutants in tap and river water also. We propose for the first time a new tack for the construction of VSA in a general manner, namely using three-dimensional full range fluorescence scanning for IFE based sensing to get multiple times of information resulting from different weak interaction between analyte and sensor for decision-making.
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CHEMOSPHERE
·
2023
·
IF 8.8
Zhujun Luo,Wantang Huang,Wenyan Yu,Shaoyu Tang,Kun Wei,Yuanyuan Yu,Lei Xu,Hua Yin,Junfeng Niu
Tris (2-butoxyethyl) phosphate (TBOEP) has gained significant attention due to its widespread presence and potential toxicity in the environment. In this study, the degradation of TBOEP in aquatic media was investigated using electrochemical oxidation technology . The anode Ti/SnO 2 –Sb/La–PbO 2 demonstrated effective degradation performance, with a reaction constant ( k ) of 0.6927 min −1 and energy consumption of 1.24 kW h/m 3 at 10 mA/cm 2 . CV tests, EPR tests, and quenching experiments confirmed that indirect degradation is the main degradation mechanism and ·OH radicals were the predominant reactive species, accounting for up to 93.8%. The presence of various factors, including Cl − , NO 3 − , HCO 3 − and humic acid (HA), inhibited the degradation of TBOEP, with the inhibitory effect dependent on the concentrations. A total of 13 intermediates were identified using UPLC-Orbitrap-MS/MS, and subsequent reactions led to their further degradation. Two main degradation pathways involving bond breaking, hydroxylation, and oxidation were proposed. Both Flow cytometry and the ECOSAR predictive model indicated that the intermediates exhibited lower toxic than the parent compound, resulting in a high detoxification rate of 95.9% for TBOEP. Although the impact of TBOEP on the phylum-level microbial community composition was found to be insignificant, substantial alterations in bacterial abundance were noted when examining the genus level. The dominant genus Methylotenera , representing 17.4% in the control group, decreased to 6.9% in the presence of TBOEP and slightly increased to 8.7% in the 4-min exposure group of degradation products . Electrochemical oxidation demonstrated its effectiveness for the degradation and detoxification of TBOEP in aqueous solutions, while it is essential to consider the potential impact of degradation products on sediment microbial communities.
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Journal of Environmental Sciences
·
2023
·
IF 6.9
Anqi Lu,Xiaokang Xiang,Ming Lei,Shuangshuang Huang,Bingbing Liang,Siyu Zhao,Lihua Zhu,Heqing Tang
The reduction of nitrobenzene to aniline is very important for both pollution control and chemical synthesis. Nevertheless, difficulties still remain in developing a catalytic system having high efficiency and selectivity for the production of aniline. Herein, it was found that PdO nanoparticles highly dispersed on TiO 2 support (PdO/TiO 2 ) functioned as a highly efficient catalyst for the reduction of nitrobenzene in the presence of NaBH 4 . Under favorable conditions, 95% of the added nitrobenzene (1 mmol/L) was reduced within 1 min with an ultra-low apparent activation energy of 10.8 kJ/mol by using 0.5%PdO/TiO 2 as catalysts and 2 mmol/L of NaBH 4 as reductants, and the selectivity to aniline even reached up to 98%. The active hydrogen species were perceived as dominant species during the hydrogenation of nitrobenzene by the results of isotope labeling experiments and ESR spectroscopic. A mechanism was proposed as follows: PdO activates the nitro groups and leads to in-situ generation of Pd, and the generated Pd acts as the reduction sites to produce active hydrogen species. In this catalytic system, nitrobenzene prefers to be adsorbed on the PdO nanoparticles of the PdO/TiO 2 composite. Subsequently, the addition of NaBH 4 results in-situ generation of a Pd/PdO/TiO 2 composite from the PdO/TiO 2 composite, and the Pd nanoclusters would activate NaBH 4 to generate active hydrogen species to attack the adsorbed nitro groups. This work will open up a new approach for the catalytic transfer hydrogenation of nitrobenzene to aniline in green chemistry.
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ChemistrySelect
·
2023
·Vol. 8
·期 37
·e202301117
·
IF 2.1
Mengting Chen,Meihua Zhang,Xiaoshuang Liu,Yingxin Liu
Graphical Herein, we report a highly efficient synthesis of N -arylhydroxylamines through controllable hydrogenation of nitroarenes using hydrazine hydrate as a hydrogen donor over Pt/C catalyst at a low temperature (30 °C). The synthesis of N -arylhydroxylamines through the in-situ hydrogenation of nitroarenes over commercial Pt/C catalyst was investigated. The effects of various reaction conditions including hydrogen donor, solvent, catalyst dosage, temperature and reaction time on the selective hydrogenation of nitrobenzene (NB) to N -phenylhydroxylamine (PHA) were systematically investigated. The results showed that the yield of N -phenylhydroxylamine reached 87.2 % using hydrazine hydrate as hydrogen donor in N,N -dimethylformamide solvent at 30 °C for 60 min. And the catalyst showed no obvious activity loss after a 6-times recycle. Meanwhile, the developed methodology can also transform a range of nitroarenes to the corresponding N -arylhydroxylamines in excellent yields (74–99 %).
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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
·
2023
·Vol. 120
·期 43
·e2311585120
·
IF 11.1
Chao-Hai Gu,Song Wang,Ai-Yong Zhang,Chang Liu,Jun Jiang,Han-Qing Yu
Single-atom Fenton-like catalysis has attracted significant attention, yet the quest for controllable synthesis of single-atom catalysts (SACs) with modulation of electron configuration is driven by the current disadvantages of poor activity, low selectivity, narrow pH range, and ambiguous structure–performance relationship. Herein, we devised an innovative strategy, the slow-release synthesis, to fabricate superior Cu SACs by facilitating the dynamic equilibrium between metal precursor supply and anchoring site formation. In this strategy, the dynamics of anchoring site formation, metal precursor release, and their binding reaction kinetics were regulated. Bolstered by harmoniously aligned dynamics, the selective and specific monatomic binding reactions were ensured to refine controllable SACs synthesis with well-defined structure–reactivity relationship. A copious quantity of monatomic dispersed metal became deposited on the C3N4/montmorillonite (MMT) interface and surface with accessible exposure due to the convenient mass transfer within ordered MMT. The slow-release effect facilitated the generation of targeted high-quality sites by equilibrating the supply and demand of the metal precursor and anchoring site and improved the utilization ratio of metal precursors. An excellent Fenton-like reactivity for contaminant degradation was achieved by the Cu1/C3N4/MMT with diminished toxic Cu liberation. Also, the selective ·OH-mediated reaction mechanism was elucidated. Our findings provide a strategy for regulating the intractable anchoring events and optimizing the microenvironment of the monatomic metal center to synthesize superior SACs.
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