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the link project of the National Natural Science Foundation of China and Fujian Province[21776292]
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Particle Pressures in Gas-Fluidized Beds: A Computational Fluid Element Method Study
No full textThe particle stress tensor is an indispensable part of continuum theory for gas-solid flow. In this study, computational fluid dynamics-discrete element method (CFD-DEM) simulations were performed to extract the particle stress tensor in gas-fluidized beds. It was shown that the numerically extracted particle pressures exerted on the wall are in excellent agreement with the experimental data available in the literature, thus offering a direct experimental validation of the approach that extracts the particle stress tensor using the CFD-DEM method. Furthermore, it was found that (i) bubble motion is the main source of generating particle stress, (ii) the size of the transducer has no effect on the measured particle stress on the wall, (iii) the particle pressure is approximately isotropic, and (iv) the particle stress on the wall differs significantly from that inside the bed. The present study proved that the CFD-DEM method is a powerful tool to explore the physical nature of particle phase stress
Fermenting and Lignin Degradability of a White-Rot Fungus Coriolopsis trogii Using Industrial Lignin as Substrate
No full textBio-depolymerized the lignin macromolecules into low molecular lignin-derived aromatic compounds satisfies the requirement for carbon dioxide peaking and is also one of the important ways to realize lignin valorization. Coriolopsis trogii is a kind of less reported lignin-degrading white-rot fungus. The degradability of a self-isolated C. trogii TS01 on industrial lignins, including enzymatic hydrolysis lignin (EHL) and Kraft lignin (KL), was investigated in this paper. The results indicated that EHL could be used as an efficient carbon source to promote the cell growth and ligninolytic enzyme secretion of C. trogii TS01. Compared with using 2% glucose as carbon source, 1% EHL plus 1% glucose would increase the maximum cell dry weight, laccase activity, and manganese-dependent peroxidase activity of C. trogii TS01 by 24.8%, 164.1%, and 200%, respectively. However, the cell growth and ligninolytic enzyme secretion would be significantly inhibited in the case of 1% KL plus 1% glucose used as carbon source. As a result, at the 12th day of fermentation, the degradation rates of EHL and KL were 50.6% and 5.7%, respectively. The UV and FTIR analysis indicated that after been fermented by C. trogii TS01, S-unit content in EHL was decreased by 12.5% but G-unit content was increased by 53.7%. In conclusion, the research of this paper will provide a promising solution for the valorization of enzymatic hydrolysis lignin since the high biodegradation rate of lignin and high activity of ligninolytic enzymes could be achieved simultaneously
The structure-activity relationship of aromatic compounds in advanced oxidation processes:a review
No full textAdvanced oxidation processes (AOPs) are widely used as efficient technologies to treat highly toxic and harmful substances in wastewater. Taking the most representative aromatic compounds (monosubstituted benzenes, substituted phenols and heterocyclic compounds) as examples, this paper firstly introduces their structures and the structural descriptors studied in AOPs before, and the influence of structural differences in AOPs with different reactive oxygen species (ROS) on the degradation rate was discussed in detail. The structure-activity relationship of pollutants has been previously analyzed through quantitative structure-activity relationship (QSAR) model, in which ROS is a very important influencing factor. When electrophilic oxidative species attacks pollutants, aromatic compounds with electron donating groups are more favorable for degradation than aromatic compounds with electron donating groups. While nucleophilic oxidative species comes to the opposite conclusion. The choice of advanced oxidation processes, the synergistic effect of various active oxygen species and the used catalysts will also change the degradation mechanism. This makes the structure-dependent activity relationship uncertain, and different conclusions are obtained under the influence of various experimental factors
Mild Catalytic Mechanism of the Mannich Reaction for Synthesizing Methylacrolein by sec-Amine Short-Chain Aliphatic Acid Ionic Liquid Catalysts
No full textBy density functional theory (DFT), we report a detailed mechanistic study on the synthesis of methylacrolein (MAL) by a mild Mannich reaction of formaldehyde (FA) and propionaldehyde (PA) catalyzed by sec-amine short-chain aliphatic acid ionic liquids (ILs). ILs exhibit excellent catalytic activity and create mild reaction conditions (45 degrees C) by dramatically decreasing the reaction energy barrier (24.43 kcal mol(-1)) in the decomposition step of Mannich bases (MBs) comapred to without ILs. Three key intermediates observed by DFT calcutations were identified by electron spray ionization mass spectrometry (ESI-MS) analysis. We systematically investigated the catalytic effect of ILs with different sec-amines (HNR2, R = CH3, C2H5, etc.) on the activation energy and different short-chain aliphatic acids (RCOOH, R= H, CH3 et al.) on the decomposition step of MBs. This work is intended to provide a thorough explanation of the synthesis mechanism of the mild Mannich reaction of MAL catalyzed by ILs from the theoretical aspect, which may give a favorable guidance for the practical application
Mild Catalytic Mechanism of the Mannich Reaction for Synthesizing Methylacrolein by sec-Amine Short-Chain Aliphatic Acid Ionic Liquid Catalysts
No full textBy density functional theory (DFT), we report a detailed mechanistic study on the synthesis of methylacrolein (MAL) by a mild Mannich reaction of formaldehyde (FA) and propionaldehyde (PA) catalyzed by sec-amine short-chain aliphatic acid ionic liquids (ILs). ILs exhibit excellent catalytic activity and create mild reaction conditions (45 degrees C) by dramatically decreasing the reaction energy barrier (24.43 kcal mol(-1)) in the decomposition step of Mannich bases (MBs) comapred to without ILs. Three key intermediates observed by DFT calcutations were identified by electron spray ionization mass spectrometry (ESI-MS) analysis. We systematically investigated the catalytic effect of ILs with different sec-amines (HNR2, R = CH3, C2H5, etc.) on the activation energy and different short-chain aliphatic acids (RCOOH, R= H, CH3 et al.) on the decomposition step of MBs. This work is intended to provide a thorough explanation of the synthesis mechanism of the mild Mannich reaction of MAL catalyzed by ILs from the theoretical aspect, which may give a favorable guidance for the practical application
Size Control of MoSx Catalysts by Diffusion Limitation for Electrocatalytic Hydrodesulfurization
No full textElectrochemical hydrodesulfurization technology is a promising approach to remove sulfur compounds from fossil fuels, having the advantages of moderate operating condition, low energy consumption, and high automation. This method is still in the research and development stage, and the desulfurization efficiency needs to be improved. Here, we report an attempt to improve the desulfurization efficiency by increasing the active sites of catalysts. The amorphous MoSx are chosen as the catalysts and synthesized by the electrodeposition method at diffusion-limited conditions, which is regulated by either increasing the deposition potential or by adding glycerol into the electrolyte. With the decrease of chemical diffusion, the morphology of MoSx catalysts changes from continuous lamellae to dispersed nanoparticles on the surface of carbon cloth. Owing to the extensive exposure of the bridging sulfur groups S-2(2-) and undercoordinated Mo(V) regions, the MoSx particles exhibit a more than two times increase of the desulfurization efficiency, reaching 22.5% in the electrochemical hydrodesulfurization. This study shows that structure optimization of catalysts by diffusion control is a facile and general strategy to improve reaction efficiency, which may be applied to various catalysts
