Catalysts
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2018
·Vol. 8
·期 8
·326
·
IF 3.465
Peng Sun,Jun Zhang,Wenxiu Liu,Qi Wang,Wenbin Cao
In this paper, the Langmuir-Hinshelwood (L-H) model has been used to investigate the kinetics of photodegradation of gaseous benzene by nitrogen-doped TiO2(N-TiO2) at 25 °C under visible light irradiation. Experimental results show that the photoreaction coefficientkpmincreased from 3.992 × 10−6mol·kg−1·s−1to 11.55 × 10−6mol·kg−1·s−1along with increasing illumination intensity. However, the adsorption equilibrium constantKLdecreased from 1139 to 597 m3·mol−1when the illumination intensity increased from 36.7 × 104lx to 75.1 × 104lx, whereas it was 2761 m3·mol−1in the absence of light. This is contrary to the fact thatKLshould be a constant if the temperature was fixed. This phenomenon can be attributed to the breaking of the adsorption-desorption equilibrium by photocatalytically decomposition. To compensate for the disequilibrium of the adsorption-desorption process, photoreaction coefficientkpmwas introduced to the expression ofKLand the compensation form was denoted asKm.KLis an indicator of the adsorption capacity of TiO2whileKmis only an indicator of the coverage ratio of TiO2surface. The modified L-H model has been experimentally verified so it is expected to be used to predict the kinetics of the photocatalytic degradation of gaseous benzene.Keywords:modified L-H model;N-TiO2;photocatalytic degradation;benzene
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Polymer Chemistry
·
2015
·Vol. 6
·期 48
·8259-8269
·
IF 5.52
Haiyan Peng,Guannan Chen,Mingli Ni,Yan Yan,Jiaqing Zhuang,V. A. L. Roy,Robert K. Y. Li,Xiaolin Xie
Holographic polymer dispersed liquid crystals (H-PDLCs) pertain to one type of intriguing switchable electro-optical device, and there is a constant need to quantitatively understand the photopolymerization kinetics and gelation process during the formation of H-PDLCs for the purpose of improving the diffraction efficiency and driving voltage. Herein, we quantitatively investigate the effect of the photoinitibitor composed of 3,3′-carbonylbis(7-diethylaminocoumarin) (KCD) and N-phenylglycine (NPG), with initiation and inhibition functions simultaneously generated under monochromatic illumination, on the formation of H-PDLCs. The outcomes reveal that an augmentation of KCD loading from 0.3 × 10−3 to 1.4 × 10−3 mol L−1 dramatically promotes the photopolymerization rate and monomer conversion. Reversely, a further increase in KCD content drastically depresses photopolymerization. The numerical deduction shows that the kinetics complies with the classical photopolymerization kinetics characteristics in the full range of the KCD content. Counterintuitively, the gelation time almost keeps constant when the KCD content is less than 1.8 × 10−3 mol L−1, and then is able to grow by more than 4 times when the KCD loading further increases. Ketyl radical inhibition, which subsequently results in shortened weight-average chain lengths and increased gel point conversions, is believed to account for the kinetics and exceptional gelation behaviors. H-PDLCs with a scaffolding morphology are formed, and with an augmentation of the KCD content, the segregation degree and diffraction efficiency significantly improve from zero to 64% and 78 ± 11%, respectively, and then level off, allowing for the facile fabrication of glass-free colored 3D images; while the critical driving voltage gradually decreases from 8.9 ± 1.0 to 4.6 ± 0.7 V μm−1.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Fangxian Wang,Junwei Yang,Shihao Li,Junwen Liang,Yuwei Wang,Rong Du,Bo Zhou,Qiong Liu,Changping Li
Bromate is a commonly identified carcinogenic and genotoxic disinfection byproduct in water. Electrochemical debromination is an environmentally friendly and effective approach but it often suffers the limited reducing atomic H (H*) ability and high metal catalyst dosage. In this study, a unique composite catalyst comprised of ultra-low loading Cu single atoms (0.016 wt%) and Fe 2 O 3 nanoparticles supported on a Nb 2 C MXene (denoted as Cu 0.2 /Fe 0.1 /Nb 2 C) was synthesized by one-step high-temperature molten salt method. The Cu 0.2 /Fe 0.1 /Nb 2 C significantly outperformed the Nb 2 C, Cu 0.2 /Nb 2 C and Fe 0.1 /Nb 2 C counterparts in the electrochemical debromination with a 94.2 % removal efficiency of bromate. It is revealed that the introducing of Cu single atoms, efficiently promotes the adsorption of H* and inhibition of competitive H 2 evolution. The incorporation of Fe 2 O 3 nanoparticles significantly increased the electronic metal-support interaction effect between the metal components and Nb 2 C, thereby forming a noticeable electronic cloud bridge to facilitate efficient charge transfer. Ultimately, the synergistic interplay between Cu single atoms and Fe 2 O 3 nanoparticles plays a crucial role in achieving the remarkable removal performance of bromate. This work not only presents a significant instance of a synergistic catalyst involving metal single atoms and metal nanoparticles for effective electrochemical debromination but also advances the understanding of the electronic metal-support interaction.
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CHEMISTRY-A EUROPEAN JOURNAL
·
2017
·Vol. 23
·期 41
·9831-9837
·
IF 5.317
Qiang Cao,Qing Yin,Qi Chen,Zhi-Bing Dong,Bao-Hang Han
Graphical Removed from the mix : The synthesis of fluorinated iron–porphyrin conjugated porous polymers through direct C−H arylation polymerization is described (see scheme). The application of these polymers as heterogeneous catalysts for Baeyer–Villiger oxidation is also discussed. By considering the high reactivity of fluorinated iron–porphyrin and good stability of porphyrin-based porous polymers, fluorinated iron–porphyrin conjugated porous polymers ( FPOP-3 – 6 ) were synthesized through direct C−H arylation polymerization. The obtained materials are chemically and thermally stable, of which FPOP-3 exhibits the highest Brunauer–Emmett–Teller specific surface area (about 840 m 2 g −1 ). For functional studies of the obtained polymers as heterogeneous catalysts, catalytic transformation of cycloketones into lactones by oxygen through Baeyer–Villiger oxidation was used as a model reaction. Fluorinated phenyl substituents of the iron–porphyrin not only are beneficial to the conversion, but also can stabilize the porphyrin to resist catalyst breakdown. The polymer FPOP-3 , with high porosity, exhibits the best catalytic efficiency and recycling effect. The recovered catalyst also shows good catalytic activities after recycling three times with a small loss in yield.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Lei Wang,Xin Zhang,Yonggang Sun,Yulong Ma,Min Xu,Juan Zhang,Yingbo Zhu,Li Zhu,Song Qiao,Jing Ma,Jinpeng Wei,Feng Lin
Environmental H 2 O has a significant effect on the reaction mechanism and process of VOC oxidation, of which the intrinsic mechanism is hardly reported. Herein, a series of PtCu δ -MnO x catalysts with different strong metal-supported interactions were constructed by replacing some Pt species with Cu species. Among them, the PtCu 3 -MnO x catalyst exhibited superior catalytic performance (T 90 = 170 ℃), high water resistance, and long-term stability. Furthermore, in-situ diffuse reflectance infrared Fourier transform spectroscopy ( in-situ DRIFTs) showed that the acetone oxidation followed synergistic cooperation of the Langmuir-Hinshelwood (L-H) and Mars van Krevelen (MvK) mechanism. Acetone oxidation over PtCu 3 -MnO x occurred via the L-H mechanism producing surface acetate and formate species intermediate. Above 100 °C, adsorbed acetone (i.e., acetate and formate species) reacts with MnO x lattice oxygen according to the MvK mechanism to form CO 2 and H 2 O. When water vapor was present, the L-H mechanism was impaired, inhibiting the deep oxidation of acetone. This research provides an in-depth exploration of how water vapor impacts the reaction mechanism of acetone oxidation. It offers valuable insights for creating dependable catalysts suitable for use in various industrial settings.
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MOLECULES
·
2024
·Vol. 29
·期 16
·3747
·
IF 4.2
Guanyu Chen,Weixin Zhang,Rongshu Zhu,Yanpeng Chen,Minghu Zhao,Mei Hong
Zeolite-based catalysts efficiently catalyze the selective catalytic reduction of NOxwith methane (CH4-SCR) for the environmentally friendly removal of nitrogen oxides, but suffer severe deactivation in high-temperature SO2- and H2O-containing flue gas. In this work, SSZ-39 zeolite (AEI topology) with high hydrothermal stability is reported for preparing CH4-SCR catalysts. Mild acid leaching with oxalic acid (OA) not only modulates the Si/Al ratio of commercial SSZ-39 to a suitable value, but also removes some extra-framework Al atoms, introducing a small number of mesopores into the zeolite that alleviate diffusion limitation. Additional Co3O4modification during indium exchange further enhances the catalytic activity of the resulting In-Co3O4/H-SSZ-39(OA). The optimized sample exhibits remarkable performance in CH4-SCR under a gas hourly space velocity (GHSV) of 24,000 h−1and in the presence of 5 vol% H2O. Even under harsh SO2- and H2O-containing high-temperature conditions, it shows satisfactory stability. Catalysts containing Co3O4components demonstrate much higher CH4conversion. The strong mutual interaction between Co3O4and Brønsted acid sites, confirmed by the temperature-programmed desorption of NO (NO-TPD), enables more stable NxOyspecies to be retained in In-Co3O4/H-SSZ-39(OA) to supply further reactions at high temperatures.
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CHEMICAL ENGINEERING SCIENCE
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2024
·
IF 4.1
Shandi Zhong,Cai Xu,Quanfu Long,Hang Zhou,Jianhai Yang,Jia Guo,Xiaozhong Wang,Liyan Dai
Using O 2 as an oxidant, developing a non-noble metal catalyst for the selective catalytic C–H bond oxidation of p-chlorotoluene is desirable and challenging. In this work, a series of Co, Cr co-doped OMS-2 (Octahedral Molecular Sieve-2) catalysts were prepared by a conventional refluxing method. It was found that the incorporation of Co and Cr improved the catalytic activity for the selective oxidation of p-chlorotoluene to p-chlorobenzaldehyde. Among these catalysts, CoCr/OMS-2 (Co: Cr = 1: 1, mass ratio), the best catalyst, shows that the conversion and the selectivity of p-chlorobenzaldehyde is 94.8 % and 94.3 %, respectively. The enhanced catalytic activity was due to the larger specific surface area and even dispersion of active components. The characterization results also disclosed that the co-doping of Co and Cr increased the oxygen vacancy and enhanced the ability to activate the surface lattice oxygen. Additionally, density functional theory calculations demonstrated that co-doping of Co and Cr promoted the adsorption of p-chlorotoluene and O 2 , and decreased the energy barrier of rate-determining step (the conversion of p-chlorobenzyl alcohol to p-chlorobenzaldehyde). Besides, when H 2 O was added to the reaction system as the second solvent, the activation and dissociation of O 2 , and the formation of p-chlorobenzaldehyde were facilitated, in agreement with the experimental results. This work demonstrated the promotional effect of Co, Cr co-doped into OMS-2 catalyst and the role of H 2 O for the selective oxidation of p-chlorotoluene.
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CEMENT & CONCRETE COMPOSITES
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2024
·
IF 10.8
Guangpeng He,Deyu Kong,Xiaoguang Chen,Shujing Fan,Tao Meng,Jiabin Li
In this paper, low-cost dihydrate gypsum (CaSO 4 ⋅2H 2 O) was used as calcium source together with sodium metasilicate solution to prepare calcium silicate hydrate (C-S-H) gels through a mechanochemical activation strategy by using planetary and vibrational ball-milling. The influences of the prepared C-S-H gels on hydrating and hardening properties of super-retarded cement-based materials with sucrose were investigated. The results showed that CaSO 4 ⋅2H 2 O reacted with sodium metasilicate solution under mechanochemical effect during both planetary and vibrational ball-milling, although CaSO 4 ⋅2H 2 O was just slightly dissolved in water. It was also interestingly found that the C-S-H gels can continuously form while resting for a certain time after ball-milling. Under the mechanochemical activation, the prepared C-S-H gels had complete characteristic diffusion peaks and were composed of layered, flocculent and fibrous structures. While incorporating the prepared C-S-H gels into the super-retarded cement paste with sucrose, the cement hydration was greatly accelerated and the compressive strength of the hardened cement-based materials was also effectively improved at early age as expected. Through X-ray diffraction (XRD) analysis, it was found that C-S-H gels can effectively promote the growth of CH crystals along the (001) and (101) crystal planes. The scanning electron microscopy (SEM) results supported that the C-S-H gels inhibited the refinement of ettringite (AFt) crystals in super-retarded HCP with sucrose, which was more obvious at 28 d.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Zhuo Li,EnZhou Liu,Carlota Bozal-Ginesta,HaiXia Ma,HuiYong Chen,Bing Wang
The rational design of stable charge-transfer pathways remains a critical challenge in advancing S-scheme photocatalytic systems. Herein, we demonstrate a hydrogen-bond-engineered dual mortise-and-tenon supramolecular architecture using precisely tailored H 12 SubPcB-OCONapOH (SubPc-5) molecules, which synergistically enhance interfacial carrier dynamics and structural robustness. The SubPc-5/TiO 2 heterojunction, constructed through π-π-directed self-assembly, achieves exceptional photocatalytic degradation of oxytetracycline (90%) and tetracycline (99%) within 180 minutes, outperforming pristine TiO 2 by 3–4.5-fold in reaction kinetics. Multimodal mechanistic investigations, including in situ light-irradiated Kelvin probe analysis, synchronous irradiation X-ray photoelectron spectroscopy (SI-XPS), and density functional theory (DFT) calculations, unambiguously verify the S-scheme charge transfer between TiO 2 and SubPc-5. Theoretical investigations reveal that O 2 molecules adsorbed at the O-site on the TiO 2 (101) surface more efficiently capture photogenerated electrons compared to the Ti-site. This work pioneers a supramolecular engineering strategy for constructing mechanically stable and electronically efficient photocatalytic systems, highlighting the transformative potential of mortise-and-tenon nanostructures in environmental remediation applications.
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CONSTRUCTION AND BUILDING MATERIALS
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2024
·
IF 7.4
Xuan Hou,Shuhua Ma,Xiaohui Wang,Yanjun Ou,Ruiping Liu
Industrial waste fly ash was transformed into a fluffy C-S-H (hydrated calcium silicate) material with thermal activation process . The textural property of the material makes it easily integrated and well dispersed in cement using 2% addition. Characterization techniques such as hydration heat, XRD , thermogravimetric analysis , were carried out to elucidate the effect of this C-S-H on cement hydration : the compressive strength of cement mortar was improved beyond 25%; and the viscosity of cement paste was reduced by 22%; the volume of solidified cement expand by 10%. This advances the overall utilization of cement and improve the properties as well.
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REACTIVE & FUNCTIONAL POLYMERS
·
2024
·
IF 4.5
Zheng Cao,Han Wu,Mengxiao Yang,Zhen Li,Xin Chen,Lin Liu
It is a high demand but a great challenge to construct all-in-one ionic conductive hydrogels with excellent mechanical performances, transparency, self-adhesion, conductivity and environmental tolerance. Herein, a versatile gel platform was developed via a facile and rapid photopolymerization of acrylic acid (AA) in deep eutectic solvent (DES) with multiple roles simultaneously as water-free solvent, ionic conductor , regulator of hydrogen bond density. Benefiting from the formed crosslinking networks including covalently cross-linked polymer network and multiple dynamic interactions, the resultant PAA-DES gels exhibited high stretchability of 884.7 ± 4.9%, toughness of 31.2 ± 1.4 MJ/m 3 , fatigue resistance and recovery ability, transparency of 93%, self-adhesive strength of 472 kPa. Moreover, the inherent advantages of DES enabled the gels with good ionic conductivity (2.5 ± 0.2 mS/cm), wide working window and biocompatibility . The PAA-DES as self-adhesive ionic sensors not only possessed wide strain range (∼400%) and stability, but also displayed excellent humidity (30–80%), temperature (−40–60 °C), and sweat tolerance which could precisely and steadily discern and monitor human motions and weak physiological signals. Thus, this work not only provides a strategy to construct all-in-one ionic conductive gels with high elasticity, fatigue resilience, transparency, self-adhesion and wide environmental tolerance, but also exploits versatile platform for intelligent gel sensor and e-skin.
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ADVANCED FUNCTIONAL MATERIALS
·
2024
·
IF 18.5
Peng Huang,Xinchun Chen,Wei Qi,Jisen Tian,Jianxun Xu,Kai Wang,Wenli Deng,Chenhui Zhang,Jianbin Luo
Hydrogenated diamond-like carbon (H-DLC) films are limited by their poor thermal stability, which significantly affects the tribological applications and needs improvement. Accordingly, nanodiamond (ND) and hexagonal boron nitride (h-BN) are used to address this issue. When the H-DLC surface is deposited using ND+h-BN mixture with mass ratio of 1:1 and a concentration of 0.1 mg mL −1 and vacuum-heated at 200 °C and 1 × 10 −5 Pa, a superlow friction coefficient of 0.0015 can be obtained, with a reduction of 98.33% as compared to pure H-DLC. Correspondingly, the wear rates of wear scar and wear track decreased by 81.95% and 24.83%, respectively. High vacuum thermal treatment can purify the adsorbed species on the surfaces of ND and h-BN, and produce newly-exposed dangling bonds. Simultaneously, new bonds of C-N are formed between ND and h-BN, and the nanoparticles adhere together to form a polymer-like structure under friction. Furthermore, the ND can support h-BN and reduce its agglomeration. Under the action of tribochemical reaction, the layer spacing of hexagonal boron nitride is increased to obtain a better shear slip. The combination of these factors resulted in ultra-low friction. This study paved the way for developing functional anti-friction additives for durable and high-performance lubrication.
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