INORGANIC CHEMISTRY
·
2013
·
IF 4.593
Lei Dong,Yujuan Wang,Yanzong Lv,Zhuqi Chen,Fuming Mei,Hui Xiong,Guochuan Yin
Redox-inactive metal ions have been recognized to be able to participate in redox metal-ion-mediated biological and chemical oxidative events; however, their roles are still elusive. This work presents how the redox-inactive metal ions affect the oxidative reactivity of a well-investigated manganese(II) with its corresponding manganese(IV) complexes having cross-bridged cyclam ligand. In dry acetone, the presence of these metal ions can greatly accelerate stoichiometric oxidations of triphenylphosphine and sulfides by the manganese(IV) complexes through electron transfer or catalytic sulfoxidations by the corresponding manganese(II) complexes with PhIO. Significantly, the rate enhancements are highly Lewis-acid strength dependent on added metal ions. These metal ions like Al3+ can also promote the thermodynamic driving force of the MnIV–OH moiety to facilitate its hydrogen abstraction from ethylbenzene having a BDECH value of 85 kcal/mol, while it is experimentally limited to 80 kcal/mol for MnIV–OH alone. Adding Al3+ may also improve the manganese(II)-catalyzed olefin epoxidation with PhIO. However, compared with those in electron transfer, improvements in hydrogen abstraction and electron transfer are minor. The existence of the interaction between Lewis acid and the manganese(IV) species was evidenced by the blue shift of the characteristic absorbance of the manganese(IV) species from 554 to 537 nm and by converting its EPR signal at g = 2.01 into a hyperfine 6-line signal upon adding Al3+ (I = 5/2). Cyclic voltammograms of the manganese(IV) complexes reveal that adding Lewis acid would substantially shift its potential to the positive direction, thus enhancing its oxidizing capability.
研究领域:
化学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysis Science & Technology
·
2023
·Vol. 13
·期 22
·6561-6569
·
IF 5
Songlei Mo,Yong Guo,Xiaohui Liu,Yanqin Wang
The glycolysis of polyethylene terephthalate (PET) is considered as the most promising PET recycling strategy due to its mild reaction conditions and circularity. Herein, several metal-doped SBA-15 (M/SBA-15) as heterogeneous Lewis acid catalysts were investigated to screen the best catalyst and to understand the essence for their differences in PET glycolysis. It is found that the catalytic activity is positively correlated with the acid amount in different metal-doped SBA-15 and Ti/SBA-15 with different Ti loadings, with the exception of Nb/SBA-15. 4Ti/SBA-15 with abundant Lewis acid sites shows excellent PET glycolysis ability, with the yield of bis(2-hydroxyethyl) terephthalate (BHET) reaching 87.2% within 45 min at 190 °C (isolated yield 73%). While 4Nb/SBA-15 has a similar acid amount as that in 4Ti/SBA-15, but it has very low catalytic activity probably due to its strong oxygen affinity. Acetone–methanol-adsorption DRIFTS confirms its strong oxygen affinity, which would poison the acid sites by ethylene glycol (EG) and result in very low activity. This study demonstrates that PET glycolysis activity is really correlated with the amount of Lewis acid sites, but species with very strong oxygen affinity would lower its activity. Further diffuse reflection ultraviolet-visible (DR UV-vis) spectra analysis confirms that tetrahedral Ti4+ species in Ti/SBA-15 is the real active center. In addition, 4Ti/SBA-15 has good reusability and can be used in common real PET (dyed polyester fabric, PET bottles) glycolysis. These results indicate that increasing the amount of Lewis acid sites is a promising way to enhance PET glycolysis and 4Ti/SBA-15 with high activity and stability is a potential catalyst for industrial application.
研究领域:
材料科学
·
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2023
·
IF 5.9
Md Asraful Alam,Liya Deng,Ange Douglas Potchamyou Ngatcha,Aymard Didier Tamafo Fouegue,Jingcheng Wu,Shen Zhang,Anqi Zhao,Wenlong Xiong,Jingliang Xu
Traditional two steps biodiesel production process generally involves corrosive sulfuric acid in the transesterification step, which is not environmentally benign. In this work, a novel procedure was presented for the direct production of biodiesel using Lewis acid deep eutectic solvent (LADES) to avoid using sulfuric acid. Synergy between the Lewis site of the LADES catalyst and the Brønsted site from biomass pretreated by Brønsted acidic deep eutectic (BADES) has resulted in the development of a bifunctional medium considered to be appropriate for high biodiesel formation and increase the FAMEs weight. The mechanism of biodiesel formation was anticipated through the experimental and computational studies of Lewis and/or Brönsted acid sites in the reaction process. The potential interference factors of the extraction process such as time of reaction, temperature, LADES catalyst concentration in methanol, and solvent volume were further optimized experimentally, followed by the Box–Behnken method. The highest amount (39.86 mg/g) of fatty acid methyl esters (FAMEs) was obtained from Chlorella pyrenoidosa biomass at 120 °C for 90 min, 5 mL solvent volume, and 5% concentration of LADES (ChCl-CrCl 3 .6 H 2 O) catalyst in methanol. The predominant FAMEs were C16:0 (9.47 mg/g), C18:2 (12.42 mg/g), and C18:3 (8.68 mg/g), and obtained biodiesel qualities meet international standards. The recyclability of LADES was tested, and satisfactory results of FAME weight were observed up to three cycles, and the FTIR peaks of LADES catalyst after four cycles of reusing have shown the structure of DES remain stable. Despite the existence of sustainable, efficient, and less toxic ways for microalgae transesterification, further investigation is required to assess the scalability of these methods for large-scale use.
研究领域:
生物技术
·
能源科学
·
环境科学
✓ 已验证
DOI
高影响因子
DESALINATION
·
2024
·
IF 8.3
Xiaowen Huo,Yingying Zhao,Zhaojing Jing,Jian Wang,Haitao Wang,Na Chang
One of the main approaches to improve the permeability of membranes is the preparation of PA layers with nanostructures based on metal organic framework (MOF) materials. However, the interaction between MOF additives and PIP/TMC monomers and the mechanisms affecting the interfacial polymerization process have not been elucidated. In this study, the adsorption conformation between the two-phase monomers and UiO-66 (UiO-66-TFA) was established by density functional theory (DFT) calculations based on Lewis acid-base theory. The results showed that the hydrogen bonding force between UiO-66 (UiO-66-TFA) with defect structures and PIP (−199.62 kcal/mol) was significantly stronger than that between UiO-66-TFA and TMC (−26.39 kcal/mol). Moreover, two PA layers with ridged and granular morphologies were prepared by dispersing UiO-66/UiO-66-TFA in the water/organic phase to influence interfacial polymerization, using UiO-66-TFA nanoparticles as additives. Among them, the PA layers showed more pronounced morphological transformation and excellent separation properties when UiO-66-TFA was used as an additive in the aqueous phase . The representative ridge-like nanostructured nanofiltration membrane showed a pure water flux of 27.51 L·m −2 ·h −1 and 98.8 % retention of Na 2 SO 4 . This study provides a new idea for the preparation of PA layers with different surface nanostructures based on the IP reaction of nano-additives.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Caihong Lv,Xin Zhou,Cheng Chen,Xinghai Liu,Jun Qian
Ammonia serves as a crucial indicator of food spoilage, but current sensors lack sufficient sensitivity, stability, selectivity, and automation for practical on-site and real-time monitoring. A highly sensitive and flexible ammonia sensor based on PEDOT:PSS doped with Lewis acid (FeCl 3 solution) for wireless food monitoring is proposed in this study to solve the above limitations. The intercalation effect caused by the diffusion of Fe 3+ and hydrolyzed H + in the film coordinating with SO 3 − groups present in PSS chains leads to an increased distance between adjacent PEDOT-rich domains. It enhances ammonia sensitivity by providing additional ionic carriers and carrier transport paths within the PEDOT:PSS molecule. The results demonstrated a significant enhancement in the sensitivity of PEDOT:PSS sensor doped with FeCl 3 , exhibiting a response value of about 25 % at 25 ℃ for 1 ppm NH 3 , with an impressive detection limit of 0.23 ppm and quantification limit of 0.78 ppm (1–400 ppm). Moreover, it showcases acceptable repeatability both at 1 ppm (RSD = 4.30 %) and 100 ppm ammonia (RSD = 3.61 %), along with the notable selectivity and long-term stability. XPS, Raman analysis, and the density function theory (DFT) calculations further elucidated the sensing mechanism of the sensor towards ammonia. Additionally, a portable wireless detection device was designed, which was equipped with the Bluetooth communication and the micro-controller system to detect the decay process of fresh shrimp, realizing wirelessly real-time monitoring of food freshness through a smart phone. It’s worth noting that the innovative sensing technology holds great promise for food quality monitoring.
研究领域:
食品科学
·
材料科学
·
传感技术
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2015
·
IF 3.352
Hui-Ying Sun,Lin-Ping Sun,Fei Li,Long Zhang
The adsorption of benzothiophene from fuels on NaY zeolites modified with 0.09 M NaOH aqueous solution was investigated. The sulfur removal reached to 99.9%, and the adsorption capacity was 1.65 mg benzothiophene/g of the modified adsorbent. The results of the scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and N 2 adsorption–desorption isotherms analyses show that mesopores appeared on the surface of NaY-0.09 adsorbent and the intrinsic crystallinity was preserved after the modification. Py-IR and NH 3 -TPD analyses indicated that the adsorption of benzothiophene occurred on the weak Lewis acid sites on the adsorbent. Both an increase in the number of the weak Lewis acid sites and the formation of mesopores on NaY-0.09 adsorbent improved its desulfurization activity.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Guangyao Zhai,Yuanyuan Liu,Yuyin Mao,Honggang Zhang,Lingtong Lin,Yujie Li,Zeyan Wang,Hefeng Cheng,Peng Wang,Zhaoke Zheng,Ying Dai,Baibiao Huang
CO 2 cycloaddition reaction from propylene oxide and CO 2 to cyclic carbonates is a desirable process to become carbon neutral. Photo energy can decrease the temperature and pressure needed for this reaction according to our previous results. However, the relationship between Lewis acidity and the photophysical process needs to be clarified and optimized. Hence, in this work, Zn is introduced into UiO-bpydc via the coordination of Zn with the bipyridyl group in bpydc. It is found that the introduction of Zn not only effectively activate propylene oxide, but also promote ligand to metal charge transfer (LMCT) process, which ultimately is beneficial for CO 2 activation. However, Ce plays a negative effect under light irradiation. namely, the presence of Ce facilitates the energy transfer process rather than the LMCT process.
研究领域:
材料科学
·
催化化学
·
光催化
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2023
·Vol. 13
·期 15
·10110-10122
·
IF 3.9
Ange Douglas Potchamyou Ngatcha,Anqi Zhao,Shen Zhang,Wenlong Xiong,Moinuddin Sarker,Jingliang Xu,Md. Asraful Alam
Experimental and theoretical considerations for kinetic modeling of the transesterification reaction of microalgae lipids into biodiesel were investigated using Lewis acid deep eutectic solvents (DESs) as a catalyst. The acid sites involved in the reaction were characterized using acetonitrile as a probe to understand the mechanism. DES ChCl–SnCl2 (choline chloride–tin II chloride) showed higher catalytic activity in transesterification due to its higher acidity compared to DES ChCl–ZnCl2 (choline chloride–zinc chloride). This was illustrated by geometric optimization of the DES structures through density functional theory (DFT) which showed that the metal centers furthest from the choline moiety are the most acidic and the bond lengths of Sn–Cl were between 2.56 and 2.77 Å, and were greater than the Zn–Cl bond lengths from 2.30 to 2.48 Å, making the ChCl–SnCl2 DES more acidic and more suitable for the biodiesel production. The fatty acid methyl ester (FAME) conversion from microalgae lipid was 36.75 mg g−1 under ideal conditions (6 molar ratio methanol–lipid with 8 vol% DES dosage in methanol at 140 °C for 420 min). The activation energy is found to be 36.3 kJ mol−1 based on the pseudo-first-order reaction, in addition, the DES catalyst (ChCl–SnCl2) drove the reaction chemically and did not show mass transfer limitation. Information from this study can help to advance the development of an efficient and environmentally friendly industrial biodiesel production technology.
研究领域:
生物化学
·
可再生能源
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
·
2013
·Vol. 2013
·期 32
·7411-7420
·
IF 3.344
Zhengkai Chen,Weijun Yang,Lijun Xu,Lili Zhang,Maozhong Miao,Hongjun Ren
Graphical Highly substituted 2-hydroxyflavanones can be obtained through a tandem O -arylation/hydroxylation process from triazenylaryl-substituted diketones in the presence of a Lewis acid. A transition-metal-free tandem O -arylation/hydroxylation approach has been developed for the efficient synthesis of highly substituted 2-hydroxyflavanones from triazenylaryl-substituted diketones. The intermediate benzopyrylium cation may be involved in these reactions.
研究领域:
有机化学
·
药物化学
✓ 已验证
DOI
高影响因子
DALTON TRANSACTIONS
·
2024
·
IF 3.5
Zhengyan Wang,Chenhao Yuan,Dong Yang,Mifen Cui,Jihai Tang,Zhuxiu Zhang,Xu Qiao
It is of great significance to develop catalysts for the degradation of hexachlorobenzene from the industrial thermal process. In this paper, formic acid was used as a modulator to generate defect sites in Ce/Zr-UiO-66 with intrinsic Brønsted acidity. The defective formate ligands were removed through methanol–water vapor treatment to expose additional open metal sites with Lewis acidity. The intrinsic Brønsted acid sites of the resulting Ce/Zr-UiO-66-FA-P achieved a hexachlorobenzene degradation efficiency of 99.5% at 250 °C. The generated Lewis acid sites facilitated the C–C cleavage of degradation intermediates. More than 95.0% of the final products were CO2/CO, coupled with chlorinated alkanes/alkenes, which outperformed other benchmark metal oxide catalysts. The Ce/Zr-UiO-66-FA-P catalyst maintained its catalytic activity in the model industrial flue gas and humid environment. The degradation pathway of hexachlorobenzene was tracked using in situ FT-IR spectra.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2016
·
IF 3.349
Xing Chu,Dan Zhou,Dan Li,Kun Xia,Ning Gan,Xinhuan Lu,Renfeng Nie,Qinghua Xia
This work has firstly constructed purely Lewis acidic sites on MCM-41 successfully, for which Zr-MCM-41 catalysts with different Zr contents are prepared through the hydrolysis of ZrOCl 2 on MCM-41, followed by calcination . Thus-prepared materials possess typical hexagonal mesostructures, irregular morphologies, large surface areas, and large pore sizes, as revealed by XRD , SEM, TEM, N 2 adsorption, and DRIFT FTIR. UV–vis, Raman and XPS spectra prove the formation of isolated species in high dispersion on the surface of MCM-41. NH 3 -TPD analysis shows that the acid intensity of the catalysts is proportional to the content of Zr, and the acidity of Zr-MCM-41 with the Zr content of <0.5% is very weak. Pyridine-IR spectra show that the surface acidity is mainly consisted of Lewis acidity, and solely Lewis acidic sites are constructed on Zr-MCM-41(550) with a low Zr content < 0.5 wt%. More Lewis acidic sites exposed on the surface of Zr-MCM-41 are considerably important for promoting the titled Prins condensation.
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
Molecular Catalysis
·
2021
·
IF 5.062
Jing Zhao,Hucheng Zhang,Haiyan Wang,Jianji Wang
A highly attractive aim is to turn CO 2 into useful chemicals selectively and efficiently, but it still retains great challenging to understand the relations between catalytic performances and interface properties. Here, we report an alternative solution to relate the catalytic activity with the strengths of Lewis acids and bases on the Pd-CoO x interfaces. CoO∙TiO 2 /TiO 2 and CoO x /TiO 2 possess the wide spectrum of Lewis acid/base centres, and give the low selectivity and conversion. The introduction of Pd can focus them on the intrinsic centres, and makes Pd-CoO∙TiO 2 /TiO 2 and Pd-CoO x /TiO 2 represent the ideal catalysis. With temperature-programmed desorptions of CO 2 , CO and NH 3 , it is evidenced that the catalytic hydrogenations of CO 2 to CO, CH 4 and CH 3 OH depend on the cooperation of the Lewis acidic/alkaline centres on the interfaces. The studies provide guidelines for rational design and synthesis of heterogeneous catalysts including but not limited to CO 2 hydrogenation.
研究领域:
化学工程
·
催化科学
✓ 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）