Select
Review of plasma-assisted reactions and potential applications for modification of metal–organic frameworks
Tingting Zhao, Niamat Ullah, Yajun Hui, Zhenhua Li
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 444-457.
https://doi.org/10.1007/s11705-019-1811-6
Plasma catalysis is drawing increasing attention worldwide. Plasma is a partially ionized gas comprising electrons, ions, molecules, radicals, and photons. Integration of catalysis and plasma can enhance catalytic activity and stability. Some thermodynamically unfavorable reactions can easily occur with plasma assistance. Compared to traditional thermal catalysis, plasma reactors can save energy because they can be operated at much lower temperatures or even room temperature. Additionally, the low bulk temperature of cold plasma makes it a good alternative for treatment of temperature-sensitive materials. In this review, we summarize the plasma-assisted reactions involved in dry reforming of methane, CO2 methanation, the methane coupling reaction, and volatile organic compound abatement. Applications of plasma for modification of metal–organic frameworks are discussed.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Mass transport mechanisms within pervaporation membranes
Yimeng Song, Fusheng Pan, Ying Li, Kaidong Quan, Zhongyi Jiang
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 458-474.
https://doi.org/10.1007/s11705-018-1780-1
Pervaporation is an energy-efficient membrane technology for separating liquid molecules of similar physical properties, which may compete or combine with distillation separation technology in a number of applications. With the rapid development of new membrane materials, the pervaporation performance was significantly improved. Fundamental understanding of the mass transport mechanisms is crucial for the rational design of membrane materials and efficient intensification of pervaporation process. Based on the interactions between permeate molecules and membranes, this review focuses on two categories of mass transport mechanisms within pervaporation membranes: physical mechanism (solution-diffusion mechanism, molecular sieving mechanism) and chemical mechanism (facilitated transport mechanism). Furthermore, the optimal integration and evolution of different mass transport mechanisms are briefly introduced. Material selection and relevant applications are highlighted under the guidance of mass transport mechanisms. Finally, the current challenges and future perspectives are tentatively identified.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Plasma-electrochemical synthesis of europium doped cerium oxide nanoparticles
Liangliang Lin, Xintong Ma, Sirui Li, Marly Wouters, Volker Hessel
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 501-510.
https://doi.org/10.1007/s11705-019-1810-7
In the present study, a plasma-electrochemical method was demonstrated for the synthesis of europium doped ceria nanoparticles. Ce(NO3 )3 ·6H2 O and Eu(NO3 )3 ·5H2 O were used as the starting materials and being dissolved in the distilled water as the electrolyte solution. The plasma-liquid interaction process was in-situ investigated by an optical emission spectroscopy, and the obtained products were characterized by complementary analytical methods. Results showed that crystalline cubic CeO2 :Eu3+ nanoparticles were successfully obtained, with a particle size in the range from 30 to 60 nm. The crystal structure didn’t change during the calcination at a temperature from 400°C to 1000°C, with the average crystallite size being estimated to be 52 nm at 1000°C. Eu3+ ions were shown to be effectively and uniformly doped into the CeO2 lattices. As a result, the obtained nanophosphors emit apparent red color under the UV irradiation, which can be easily observed by naked eye. The photoluminescence spectrum further proves the downshift behavior of the obtained products, where characteristic 5 D0 →7 F1,2,3 transitions of Eu3+ ions had been detected. Due to the simple, flexible and environmental friendly process, this plasma-electrochemical method should have great potential for the synthesis of a series of nanophosphors, especially for bio-application purpose.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Low-k integration: Gas screening for cryogenic etching and plasma damage mitigation
Romain Chanson, Remi Dussart, Thomas Tillocher, P. Lefaucheux, Christian Dussarrat, Jean François de Marneffe
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 511-516.
https://doi.org/10.1007/s11705-019-1820-5
The integration of porous organo-silicate low-k materials has met a lot of technical challenges. One of the main issues is plasma-induced damage, occurring for all plasma steps involved during interconnects processing. In the present paper, we focus on porous SiOCH low-k damage mitigation using cryogenic temperature so as to enable micro-capillary condensation. The aim is to protect the porous low-k from plasma-induced damage and keep the k -value of the material unchanged, in order to limit the RC delay of interconnexion levels while shrinking the microchip dimension. The cryogenic temperature is used to condense a gas inside the porous low-k material. Then, the etching process is performed at the temperature of condensation in order to keep the condensate trapped inside the material during the etching. In the first part of this work, the condensation properties of several gases are screened, leading to a down selection of five gases. Then, their stability into the porous structure is evaluated at different temperature. Four of them are used for plasma damage mitigation comparison. Damage mitigation is effective and shows negligible damage for one of the gases at –50°C.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Effect of TiO2 loading on the morphology and CO2 /CH4 separation performance of PEBAX-based membranes
Navid Azizi, Mojgan Isanejad, Toraj Mohammadi, Reza M. Behbahani
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 517-530.
https://doi.org/10.1007/s11705-018-1781-0
Membranes have attracted much attention as economical methods for industrial chemical processes. The effects of the titanium dioxide nanoparticle load on the morphology and CO2 /CH4 separation performance of poly (ether-block-amide) (PEBAX-1657) mixed matrix membranes (MMMs) were investigated from pressures of 3–12 bar and temperatures of 30°C–60°C. The PEBAX membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and tensile strength analysis. The incorporation of TiO2 nanoparticles into the polymeric MMMs improved the CO2 /CH4 gas separation performance (both the permeability and selectivity) of the membranes. The CO2 permeability and ideal CO2 /CH4 selectivity values of the nanocomposite membrane loaded with 8 wt-% TiO2 were 172.32 Barrer and 24.79, respectively whereas those of the neat membrane were 129.87 Barrer and 21.39, respectively.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Synthesis of hydroxymethylfurfural and furfural from hardwood and softwood pulp using ferric sulphate as catalyst
Agneev Mukherjee, Guillermo Portillo-Perez, Marie-Josée Dumont
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 531-542.
https://doi.org/10.1007/s11705-019-1814-3
Hydroxymethylfurfural (HMF) and furfural are promising chemicals for the creation of a bio-based economy. The development of an inexpensive catalytic system for converting cellulosic biomass into these chemicals is an important step in this regard. Ferric sulphate is a common, cheap and non-toxic Lewis acid that has been used to catalyse reactions such as wood depolymerisation. In this work, ferric sulphate was used to help the production of HMF and furfural from hardwood and softwood pulps. It was found that for hardwood pulp, the use of ferric sulphate alone gave a maximum HMF yield of 31.6 mol-%. The addition of the ionic liquid [BMIM]Cl or HCl as co-catalysts did not lead to an increase in the yields obtained. A prior decationisation step, however, resulted in HMF yields of 50.4 mol-%. Softwood pulp was harder to depolymerise than hardwood, with a yield of 28.7% obtained using ferric sulphate alone. The maximum HMF yield from softwood, 37.9 mol-%, was obtained using a combination of ferric sulphate and dilute HCl. It was thus concluded that ferric sulphate is a promising catalyst for HMF synthesis from cellulosic biomass.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Dealumination and desilication for Al-rich HZSM-5 zeolite via steam-alkaline treatment and its application in methanol aromatization
Yuehua Fang, Fan Yang, Xuan He, Xuedong Zhu
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 543-553.
https://doi.org/10.1007/s11705-018-1778-8
The hierarchical HZSM-5 was prepared via dealumination and desilication of commercial Al-rich HZSM-5, and characterized by X-ray diffraction, 27 Al magic-angle spinning nuclear magnetic resonance, inductively coupled plasma mass spectrometry, scanning electron microscope, transmission electron microscope, N2 adsorption-desorption, NH3 temperature-programmed desorption, performed thermogravimetric and Raman spectrum. The results showed that partial framework of HZSM-5 was removed after steam treatment at 0.15 MPa, 500°C for 3 h. HZSM-5 with high specific surface area and much mesoporosity was obtained by the subsequent alkaline treatment. The regulation of acid quantity was achieved by altering the concentration of alkaline. Dealumination and desilication of Al-rich HZSM-5 zeolites became more effective using a combination of steam and alkaline treatments than using alkaline treatment alone. Methanol aromatization reaction was employed to evaluate the catalytic performance of treated HZSM-5 at 0.15 MPa, 450°C and MHSV of 1.5 h−1 . The results indicated that after steam treatment, HZSM-5 further treated with 0.2 mol/L NaOH exhibits the best catalytic performance: the selectivity of aromatics reached 42.1% and the lifetime of catalyst attained 212 h, which are much better than untreated HZSM-5.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Construction of a CaHPO4 -PGUS1 hybrid nanoflower through protein-inorganic self-assembly, and its application in glycyrrhetinic acid 3-O -mono-β -D-glucuronide preparation
Tian Jiang, Yuhui Hou, Tengjiang Zhang, Xudong Feng, Chun Li
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 554-562.
https://doi.org/10.1007/s11705-019-1834-z
Glycyrrhetinic acid 3-O -mono-b -D-glucuronide (GAMG), an important pharmaceutical intermediate and functional sweetener, has broad applications in the food and medical industries. A green and cost-effective method for its preparation is highly desired. Using site-directed mutagenesis, we previously obtained a variant of β -glucuronidase from Aspergillus oryzae Li-3 (PGUS1), which can specifically transform glycyrrhizin (GL) into GAMG. In this study, a facile method was established to prepare a CaHPO4 -PGUS1 hybrid nanoflower for enzyme immobilization, based on protein-inorganic hybrid self-assembly. Under optimal conditions, 1.2 mg of a CaHPO4 -PGUS1 hybrid nanoflower precipitate with 71.2% immobilization efficiency, 35.60 mg·g−1 loading capacity, and 118% relative activity was obtained. Confocal laser scanning microscope and scanning electron microscope results showed that the enzyme was encapsulated in the CaHPO4 -PGUS1 hybrid nanoflower. Moreover, the thermostability of the CaHPO4 -PGUS1 hybrid nanoflower at 55°C was improved, and its half-life increased by 1.3 folds. Additionally, the CaHPO4 -PGUS1 hybrid nanoflower was used for the preparation of GAMG through GL hydrolysis, with the conversion rate of 92% in 8 h, and after eight consecutive runs, it had 60% of its original activity.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Deep eutectic ionic liquids based on DABCO-derived quaternary ammonium salts: A promising reaction medium in gaining access to terpyridines
Muhammad Faisal, Azeem Haider, Quret ul Aein, Aamer Saeed, Fayaz Ali Larik
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 586-598.
https://doi.org/10.1007/s11705-018-1788-6
Owing to the directional H-bonding, coordination and p -stacking abilities, terpyridines have been widely used as supramolecular tectons in molecular architectures, skeletons in molecular devices and metallopolymers, and are gaining importance in medicinal chemistry. In this paper, we have synthesized, characterized and applied deep eutectic ionic liquids (DEILs) based on 1,4-diazabicyclo[2.2.2]octane; triethylenediamine (DABCO)-derived quaternary ammonium salts for the preparation of terpyridines. These DEILs were synthesized through N -alkylation of DABCO with haloalkanes (1-bromopentane or 1-bromoheptane) followed by mixing and heating with methanol or polyethylene glycol as a hydrogen bond donor. The synthesized DEILs were structurally characterized by IR and NMR. The formation of deep eutectic solvent was confirmed by freezing point depression, it composition was investigated through phase diagram, and its thermal stability was determined through differential scanning calorimetry, derivative thermogravimetry and thermal gravimetric analysis studies. Further, these DEILs were investigated for their effectiveness towards synthesis of 2,2':6',2"-terpyridine, 3,2':6',3"-terpyridineand 4,2':6',4"-terpyridine derivatives through Kröhnke reaction. The results show that these three types of terpyridines can be obtained in reasonable yields (80%- 97%) by the one-pot reaction of 2-, 3- or 4-acetylpyridine with a variety of aromatic aldehydes in the presence of DEIL as a reaction medium, sodium hydroxide as a base and ammonium acetate as a cyclizing agent. This methodology is highly efficient and cost-effective for synthesis of symmetrical as well as unsymmetrical terpyridines. Importantly, these DEILs can be reused several times without an obvious loss of activity and are non-toxic, low-volatile, biodegradable and highly thermally stable. Therefore, these DEILs as a non-conventional reaction medium for the synthesis of terpyridines provides appealing opportunities to be investigated in the domain of green synthesis.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Modeling of oil near-infrared spectroscopy based on similarity and transfer learning algorithm
Yifei Wang, Kai Wang, Zhao Zhou, Wenli Du
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 599-607.
https://doi.org/10.1007/s11705-019-1807-2
Near-infrared spectroscopy mainly reflects the frequency-doubled and total-frequency absorption information of hydrogen-containing groups (O‒H, C‒H, N‒H, S‒H) in organic molecules for near-infrared lights with different wavelengths, so it is applicable to testing of most raw materials and products in the field of petrochemicals. However, the modeling process needs to collect a large number of laboratory analysis data. There are many oil sources in China, and oil properties change frequently. Modeling of each raw material is not only unfeasible but also will affect its engineering application efficiency. In order to achieve rapid modeling of near-infrared spectroscopy and based on historical data of different crude oils under different detection conditions, this paper discusses about the feasibility of the application of transfer learning algorithm and makes it possible that transfer learning can assist in rapid modeling using certain historical data under similar distributions under a small quantity of new data. In consideration of the requirement of transfer learning for certain similarity of different datasets, a transfer learning method based on local similarity feature selection is proposed. The simulation verification of spectral data of 13 crude oils measured by three different probe detection methods is performed. The effectiveness and application scope of the transfer modeling method under different similarity conditions are analyzed.
Figures and Tables |
References |
Related Articles |
Metrics
Select
Cryptosporidium parvum oocyst directed assembly of gold nanoparticles and graphene oxide
Sona Jain, Zhicheng Huang, Brent R. Dixon, Syed Sattar, Juewen Liu
Front. Chem. Sci. Eng.. 2019, 13 (3 ): 608-615.
https://doi.org/10.1007/s11705-019-1813-4
Understanding the interactions between inorganic nanomaterials and biological species is an important topic for surface and environmental chemistry. In this work, we systematically studied the oocysts of Cryptosporidium parvum as a model protozoan parasite and its interaction with gold nanoparticles (AuNPs) and graphene oxide (GO). The as-prepared citrate-capped AuNPs adsorb strongly on the oocysts leading to a vivid color change. The adsorption of the AuNPs was confirmed by transmission electron microscopy. Heat treatment fully inhibited the color change, indicating a large change of surface chemistry of the oocysts that can be probed by the AuNPs. Adding proteases such as trypsin and proteinase K partially inhibited the color change. DNA-capped AuNPs, on the other hand, could not be adsorbed by the oocysts. GO was found to wrap around the oocysts forming a conformal shell reflecting the shape of the oocysts. Both citrate-capped AuNPs and GO compromised the membrane integrity of the oocysts as indicated by the propidium iodide staining experiment, and they may be potentially used for inactivating the oocysts. This is the first example of using nanomaterials to probe the surface of the oocysts, and it suggests the possibility of using such organisms to template the assembly of nanomaterials.
Figures and Tables |
References |
Related Articles |
Metrics
18 articles