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Microemulsion-mediated hydrothermal synthesis of flower-like MoS2 nanomaterials with enhanced catalytic activities for anthracene hydrogenation
Yuxia Jiang, Donge Wang, Zhendong Pan, Huaijun Ma, Min Li, Jiahe Li, Anda Zheng, Guang Lv, Zhijian Tian
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 32-42.
https://doi.org/10.1007/s11705-017-1677-4
Flower-like intercalated MoS2 nanomaterials have been successfully synthesized via a microemulsion-mediated hydrothermal (MMH) method, and characterized by X-ray diffraction, Raman spectroscopy, element analysis, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy in detail. Their catalytic performance for anthracene hydrogenation was evaluated using a slurry-bed batch reactor with an initial hydrogen pressure of 80 bar at 350 °C for 4 h. The intercalated MoS2 nanoflowers synthesized from Na2 MoO4 (MoS2 -S) and H2 MoO4 (MoS2 -A) as molybdenum precursors have diameters of about 150 and 50 nm, respectively. MoS2 nanosheets on MoS2 -S and MoS2 -A possess stacking layer numbers of 5–10 and 2–5, and slab lengths of about 15 and 10 nm, respectively. The interlayer distances of MoS2 -S and MoS2 -A are both enlarged from 0.62 nm to about 0.95 nm due to the intercalation of NH4 + and surfactant molecules. The MoS2 nanoflowers have high catalytic activities for anthracene hydrogenation. The selectivity for octahydroanthracene, a deeply hydrogenated product, over MoS2 -A is 89.8%, which is 31.0 times higher than that over commercial bulk MoS2 . Fully hydrogenated product (perhydroanthracene) was also detected over MoS2 nanoflowers with a selectivity of 3.7%. The enhanced hydrogenation activities of MoS2 nanoflowers can be ascribed to the high exposure of catalytic active sites, resulting from the smaller particle size, fewer stacking layer, shorter slab length and enlarged interlayer distance of MoS2 nanoflowers compared with commercial bulk MoS2 . In addition, a possible growth mechanism of MoS2 nanoflowers synthesized via the MMH method was proposed.
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Template-free synthesis of hierarchically macro-mesoporous Mn-TiO2 catalysts for selective reduction of NO with NH3
Zhao Peng, Li-Hua Chen, Ming-Hui Sun, Pan Wu, Chang Cai, Zhao Deng, Yu Li, Wei-Hong Zheng, Bao-Lian Su
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 43-49.
https://doi.org/10.1007/s11705-017-1679-2
This study described a template-free method for the synthesis of hierarchically macro-mesoporous Mn-TiO2 catalysts. The promoting effect of Mn doping and the hierarchically macro-mesoporous architecture on TiO2 based catalysts was also investigated for the selective reduction of NO with NH3 . The results show that the catalytic performance of TiO2 based catalysts was improved greatly after Mn doping. Meanwhile, the Mn-TiO2 catalyst with the hierarchically macro-mesoporous architecture has a better catalytic activity than that without such an architecture.
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Upgrading of derived pyrolysis vapors for the production of biofuels from corncobs
Liaoyuan Mao, Yanxin Li, Z. Conrad Zhang
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 50-58.
https://doi.org/10.1007/s11705-017-1685-4
A bubbling fluidized bed pyrolyzer was integrated with an in-situ honeycomb as a catalytic upgrading zone for the conversion of biomass to liquid fuels. In the upgrading zone, zeolite coated ceramic honeycomb (ZCCH) catalysts consisting of ZSM-5 (Si/Al=25) were stacked and N2 or recycled non-condensable gas was used as a carrier gas. Ground corncob particles were fast pyrolyzed in the bubbling bed using fine sand particles as a heat carrier and the resulting pyrolysis vapors were passed on-line over the catalytic upgrading zone. The influence of carrier gas, temperature, and weight hourly space velocity (WHSV) of catalyst on the oil product properties, distribution and mass balance were studied. Using ZCCH effectively increased the hydrocarbon yield and the heating value of the dry oil, especially in the presence of the recycled noncondensable gas. Even a low usage of zeolite catalyst at WSHV of 180 h− 1 was effective in upgrading the pyrolysis oil and other light olefins. The highest hydrocarbon (≥C2) and liquid aromatics yields reached to 14.23 and 4.17 wt-%, respectively. The undesirable products including light oxygenates, furans dramatically decreased in the presence of the ZCCH catalyst.
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Novel method for the preparation of Cs-containing FAU(Y) catalysts for aniline methylation
Olga A. Ponomareva, Polina A. Shaposhnik, Marina V. Belova, Boris A. Kolozhvari, Irina I. Ivanova
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 70-76.
https://doi.org/10.1007/s11705-017-1694-3
Cs-containing FAU(Y)-type zeolite catalysts were prepared by conventional and novel ion exchange procedures followed by incipient wetness impregnation with CsOH. The novel ion exchange procedure involved hydrothermal treatment of NaY zeolite in aqueous solution of CsCl at 140–200 °C for 6–24 h. The samples were characterized by low-temperature nitrogen adsorption, X-ray fluorescence analysis, X-ray powder diffraction, scanning electron microscopy, 23 Na, 27 Al and 133 Cs magic angle spinning nuclear magnetic resonance, CO2 and NH3 -Temperature programmed desorption. The results show that hydrothermal treatment at 200 °C allows to obtain higher degrees of ion-exchange (up to 83%) with respect to conventional method giving maximum 66%–69%. Catalytic properties of Cs-containing FAU(Y) were studied in aniline methylation. The yield of N -methylaniline is shown to correlate with catalyst’s basicity. The best catalyst performance was achieved over the catalyst with the highest ion-exchange degree impregnated with CsOH. The selectivity to N -methylaniline over this catalyst reached 96.4%.
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High-precision diffusion measurement of ethane and propane over SAPO-34 zeolites for methanol-to-olefin process
Dali Cai, Yu Cui, Zhao Jia, Yao Wang, Fei Wei
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 77-82.
https://doi.org/10.1007/s11705-017-1684-5
The methanol-to-olefin (MTO) process has attracted much attention and many problems including lifetime and selectivity of light olefins have all been connected to the diffusion problems in zeolite crystals. However, a quantitative study of diffusion problems in SAPO-34 zeolites is lacking. In this paper, we performed a high-precision diffusion measurement of the diffusion behavior of ethane and propane, which represent ethylene and propylene respectively, over SAPO-34. The diffusions of ethane and propane over fresh and coked SAPO-34 zeolites with different crystal sizes were carefully studied. Ethane and propane show different diffusion behavior in SAPO-34. The diffusion of ethane is almost not influenced by the crystal size and coke percentage, whereas that of propane is strongly affected. A slower diffusion velocity was observed in bigger crystals, and the diffusion velocity decline significantly with the coke percentage increasing. The diffusion coefficient was calculated with both the internal and surface diffusion models, and the results show that the surface diffusion plays a key role in the diffusion process of both ethane and propane. We believe that this work would be helpful for understanding the diffusion of different molecules in SAPO-34 zeolites, and may lay the foundation of MTO research.
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Al2 O3 and CeO2 -promoted MgO sorbents for CO2 capture at moderate temperatures
Huimei Yu, Xiaoxing Wang, Zhu Shu, Mamoru Fujii, Chunshan Song
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 83-93.
https://doi.org/10.1007/s11705-017-1691-6
A series of Al2 O3 and CeO2 modified MgO sorbents was prepared and studied for CO2 sorption at moderate temperatures. The CO2 sorption capacity of MgO was enhanced with the addition of either Al2 O3 or CeO2 . Over Al2 O3 -MgO sorbents, the best capacity of 24.6 mg-CO2 /g-sorbent was attained at 100 °C, which was 61% higher than that of MgO (15.3 mg-CO2 /g-sorbent). The highest capacity of 35.3 mg-CO2 /g-sorbent was obtained over the CeO2 -MgO sorbents at the optimal temperature of 200 °C. Combining with the characterization results, we conclude that the promotion effect on CO2 sorption with the addition of Al2 O3 and CeO2 can be attributed to the increased surface area with reduced MgO crystallite size. Moreover, the addition of CeO2 increased the basicity of MgO phase, resulting in more increase in the CO2 capacity than Al2 O3 promoter. Both the Al2 O3 -MgO and CeO2 -MgO sorbents exhibited better cyclic stability than MgO over the course of fifteen CO2 sorption-desorption cycles. Compared to Al2 O3 , CeO2 is more effective for promoting the CO2 capacity of MgO. To enhance the CO2 capacity of MgO sorbent, increasing the basicity is more effective than the increase in the surface area.
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Detection of CO2 and O2 by iron loaded LTL zeolite films
Veselina Georgieva, Richard Retoux, Valerie Ruaux, Valentin Valtchev, Svetlana Mintova
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 94-102.
https://doi.org/10.1007/s11705-017-1692-5
Detection of oxygen and carbon dioxide is important in the field of chemical and biosensors for atmosphere and biosystem monitoring and fermentation processes. The present study reports on the preparation of zeolite films doped with iron nanoparticles for detection of CO2 and O2 in gas phase. Pure nanosized LTL type zeolite with monomodal particle size distribution loaded with iron (Fe-LTL) was prepared under hydrothermal condition from colloidal precursor suspensions. The zeolite was loaded with iron to different levels by ion exchange. The Fe-LTL suspensions were used for preparation of thin films on silicon wafers via spin coating method. The reduction of the iron in the zeolite films was carried out under H2 flow (50% H2 in Ar) at 300 °C. The presence of iron nanoparticles is proved by in situ ultra-violet-visible spectroscopy. The properties of the films including surface roughness, thickness, porosity, and mechanical stability were studied. In addition, the loading and distribution of iron in the zeolite films were investigated. The Fe-LTL zeolite films were used to detect O2 and CO2 in a concentration dependent mode, followed by IR spectroscopy. The changes in the IR bands at 855 and 642 cm− 1 (Fe–O–H and Fe–O bending vibrations) and at 2363 and 2333 cm− 1 (CO2 asymmetric stretching) corresponding to the presence of O2 and CO2 , respectively, were evaluated. The response to O2 and CO2 was instant, which was attributed to great accessibility of the iron in the nanosized zeolite crystals. The saturation of the Fe-LTL films with CO2 and O2 at each concentration was reached within less than a minute. The Fe-LTL films detected both oxygen and carbon dioxide in contrast, to the pure LTL zeolite film.
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Shape selective catalysis in methylation of toluene: Development, challenges and perspectives
Jian Zhou, Zhicheng Liu, Yangdong Wang, Dejin Kong, Zaiku Xie
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 103-112.
https://doi.org/10.1007/s11705-017-1671-x
Toluene methylation with methanol offers an alternative method to produce p -xylene by gathering methyl group directly from C1 chemical sources. It supplies a “molecular engineering” process to realize directional conversion of toluene/methanol molecules by selective catalysis in complicated methylation system. In this review, we introduce the synthesis method of p -xylene, the development history of methylation catalysts and reaction mechanism, and the effect of reaction condition in para -selective technical process. If constructing p -xylene as the single target product, the major challenge to develop para -selective toluene methylation is to improve the p -xylene selectivity without, or as little as possible, losing the fraction of methanol for methylation. To reach higher yield of p -xylene and more methanol usage in methylation, zeolite catalyst design should consider improving mass transfer and afterwards covering external acid sites by surface modification to get short “micro-tunnels” with shape selectivity. A solid understanding of mass transfer will benefit realizing the aim of converting more methanol feedstock into para -methyl group.
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Advances in the slurry reactor technology of the anthraquinone process for H2 O2 production
Hongbo Li, Bo Zheng, Zhiyong Pan, Baoning Zong, Minghua Qiao
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 124-131.
https://doi.org/10.1007/s11705-017-1676-5
This paper overviews the development of the anthraquinone auto-oxidation (AO) process for the production of hydrogen peroxide in China and abroad. The characteristics and differences between the fixed-bed and fluidized-bed reactors for the AO process are presented. The detailed comparison indicates that the production of hydrogen peroxide with the fluidized-bed reactor has many advantages, such as lower operation cost and catalyst consumption, less anthraquinone degradation, higher catalyst utilization efficiency, and higher hydrogenation efficiency. The key characters of the production technology of hydrogen peroxide based on the fluidized-bed reactor developed by the Research Institute of Petroleum Processing, Sinopec are also disclosed. It is apparent that substituting the fluidized-bed reactor for the fixed-bed reactor is a major direction of breakthrough for the production technology of hydrogen peroxide in China.
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Mesoporous zeolites for biofuel upgrading and glycerol conversion
Jian Zhang, Liang Wang, Yanyan Ji, Fang Chen, Feng-Shou Xiao
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 132-144.
https://doi.org/10.1007/s11705-017-1681-8
With the recent emphasis and development of sustainable chemistry, the conversion of biomass feedstocks into alternative fuels and fine chemicals over various heterogeneous catalysts has received much attention. In particular, owing to their uniform micropores, strong acidity, and stable and rigid frameworks, zeolites as catalysts or co-catalysts have exhibited excellent catalytic performances in many reactions, including hydrodesulfurization, Fischer-Tropsch synthesis, and hydrodeoxygenation. However, the relatively small sizes of the zeolite micropores strongly limit the conversion of bulky biomolecules. To overcome this issue, mesoporous zeolites with pores larger than those of biomolecules have been synthesized. As expected, these mesoporous zeolites have outperformed conventional zeolites with improved activities, better selectivities, and longer catalyst lives for the upgrading of pyrolysis oils, the transformation of lipids into biofuels, and the conversion of glycerol into acrolein and aromatic compounds. This review briefly summarizes recent works on the rational synthesis of mesoporous zeolites and their superior catalytic properties in biomass conversion.
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Atomistic simulations of plasma catalytic processes
Erik C. Neyts
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 145-154.
https://doi.org/10.1007/s11705-017-1674-7
There is currently a growing interest in the realisation and optimization of hybrid plasma/catalyst systems for a multitude of applications, ranging from nanotechnology to environmental chemistry. In spite of this interest, there is, however, a lack in fundamental understanding of the underlying processes in such systems. While a lot of experimental research is already being carried out to gain this understanding, only recently the first simulations have appeared in the literature. In this contribution, an overview is presented on atomic scale simulations of plasma catalytic processes as carried out in our group. In particular, this contribution focusses on plasma-assisted catalyzed carbon nanostructure growth, and plasma catalysis for greenhouse gas conversion. Attention is paid to what can routinely be done, and where challenges persist.
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Hydro-pyrolysis of lignocellulosic biomass over alumina supported Platinum, Mo2 C and WC catalysts
Songbo He, Jeffrey Boom, Rolf van der Gaast, K. Seshan
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 155-161.
https://doi.org/10.1007/s11705-017-1655-x
In-line hydro-treatment of bio-oil vapor from fast pyrolysis of lignocellulosic biomass (hydro-pyrolysis of biomass) is studied as a method of upgrading the liquefied bio-oil for a possible precursor to green fuels. The nobel metal (Pt) and non-noble metal catalysts (Mo2 C and WC) were compared at 500 °C and atmospheric pressure which are same as the reaction conditions for fast pyrolysis of biomass. Results indicated that under the pyrolysis conditions, the major components, such as acids and carbonyls, of the fast pyrolysis bio-oil can be completely and partially hydrogenated to form hydrocarbons, an ideal fossil fuel blend, in the hydro-treated bio-oil. The carbide catalysts perform equally well as the Pt catalyst regarding to the aliphatic and aromatic hydrocarbon formation (ca. 60%), showing the feasibility of using the cheap non-noble catalysts for hydro-pyrolysis of biomass.
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Comparative analysis of ceramic-carbonate nanocomposite fuel cells using composite GDC/NLC electrolyte with different perovskite structured cathode materials
Muhammad I. Asghar, Sakari Lepikko, Janne Patakangas, Janne Halme, Peter D. Lund
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 162-173.
https://doi.org/10.1007/s11705-017-1642-2
A comparative analysis of perovskite structured cathode materials, La0.65 Sr0.35 MnO3 (LSM), La0.8 Sr0.2 CoO3 (LSC), La0.6 Sr0.4 FeO3 (LSF) and La0.6 Sr0.4 Co0.2 Fe0.8 O3 (LSCF), was performed for a ceramic-carbonate nanocomposite fuel cell using composite electrolyte consisting of Gd0.1 Ce0.9 O1.95 (GDC) and a eutectic mixture of Na2 CO3 and Li2 CO3 . The compatibility of these nanocomposite electrode powder materials was investigated under air, CO2 and air/CO2 atmospheres at 550 °C. Microscopy measurements together with energy dispersive X-ray spectroscopy (EDS) elementary analysis revealed few spots with higher counts of manganese relative to lanthanum and strontium under pure CO2 atmosphere. Furthermore, electrochemical impedance (EIS) analysis showed that LSC had the lowest resistance to oxygen reduction reaction (ORR) (14.12 Ω·cm2 ) followed by LSF (15.23 Ω·cm2 ), LSCF (19.38 Ω·cm2 ) and LSM (>300 Ω·cm2 ). In addition, low frequency EIS measurements (down to 50 µHz) revealed two additional semi-circles at frequencies around 1 Hz. These semicircles can yield additional information about electrochemical reactions in the device. Finally, a fuel cell was fabricated using GDC/NLC nanocomposite electrolyte and its composite with NiO and LSCF as anode and cathode, respectively. The cell produced an excellent power density of 1.06 W/cm2 at 550 °C under fuel cell conditions.
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Strengthening of polysulfone membranes using hybrid mixtures of micro- and nano-scale modifiers
Peyman P. Selakjani, Majid Peyravi, Mohsen Jahanshahi, Hamzeh Hoseinpour, Ali S. Rad, Soodabeh Khalili
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 174-183.
https://doi.org/10.1007/s11705-017-1670-y
Polysulfone (PSf) membranes were modified by either a new organic modifier (sulfonated poly(ether sulfide sulfone), SPESS) or a traditional modifier (rice hulk). These membranes were further reinforced with either multi-walled carbon nanotubes (MWCNTs) or silica nanoparticles. Having a dye rejection of 98.46%, the reinforced membranes increased more than 50% in strength but no change in solution flux was observed. The morphological and roughness studies were conducted using scanning electron microscopy and atomic force microscopy. Moreover, the PSF membranes were also characterized by differential scanning calorimetry. Modifying the membranes with organic modifier or nanofiller increases the glass transition temperature (T g ). The highest T g and strength were observed for the PSf-SPESS-MWCNT membrane. SPESS decreases surface roughness but MWCNT increases roughness on the nanoscale. All membranes show a bimodal pore size distribution, whereas the PSf-SPESS-MWCNT membrane exhibits a relatively uniform distribution of macroscopic and microscopic pores.
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Micronization of curcumin with biodegradable polymer by supercritical anti-solvent using micro swirl mixer
Kimthet Chhouk, Wahyudiono, Hideki Kanda, Shin-Ichro Kawasaki, Motonobu Goto
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 184-193.
https://doi.org/10.1007/s11705-017-1678-3
Curcumin is a hydrophobic polyphenol compound exhibiting a wide range of biological activities such as anti-inflammatory, anti-bacterial, anti-fungal, anti-carcinogenic, anti-human immunodeficiency virus, and anti-microbial activity. In this work, a swirl mixer was employed to produce the micronized curcumin with polyvinylpyrrolidone (PVP) by the supercritical anti-solvent process to improve the bioavailability of curcumin. The effects of operating parameters such as curcumin/PVP ratio, feed concentration, temperature, pressure, and CO2 flow rate were investigated. The characterization and solubility of particles were determined by using scanning electron microscopy, Fourier Transform Infrared spectroscopy, and ultra-violet-visible spectroscopy. The result shows that the optimal condition for the production of curcumin/PVP particles is at curcumin/PVP ratio of 1:30, feed concentration of 5 mg·mL− 1 , temperature of 40 °C, pressure of 15 MPa, and CO2 flow rate of 15 mL·min− 1 . Moreover, the dissolution of curcumin/PVP particles is faster than that of raw curcumin.
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New approaches to water purification for resource-constrained settings: Production of activated biochar by chemical activation with diammonium hydrogenphosphate
Mohit Nahata, Chang Y. Seo, Pradeep Krishnakumar, Johannes Schwank
Front. Chem. Sci. Eng.. 2018, 12 (1 ): 194-208.
https://doi.org/10.1007/s11705-017-1647-x
A significant portion of the world’s population does not have access to safe drinking water. This problem is most acute in remote, resource-constrained rural settings in developing countries. Water filtration using activated carbon is one of the important steps in treating contaminated water. Lignocellulosic biomass is generally available in abundance in such locations, such as the African rain forests. Our work is focused on developing a simple method to synthesize activated biochar from locally available materials. The preparation of activated biochar with diammonium hydrogenphosphate (DAP) as the activating agent is explored under N2 flow and air. The study, carried out with cellulose as a model biomass, provides some insight into the interaction between DAP and biomass, as well as the char forming mechanism. Various characterization techniques such as N2 physisorption, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy are utilized to compare the properties between biochar formed under nitrogen and partial oxidative conditions. At a temperature of 450 °C, the loading of DAP over cellulose is systematically varied, and its effect on activation is examined. The activated biochar samples are predominantly microporous in the range of concentrations studied. The interaction of DAP with cellulose is investigated and the nature of bonding of the heteroatoms to the carbonaceous matrix is elucidated. The results indicate that the quality of biochar prepared under partial oxidation condition is comparable to that of biochar prepared under nitrogen, leading to the possibility of an activated biochar production scheme on a small scale in resource-constrained settings.
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