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dioxide photoreduction process in a laboratory-scale photoreactor by computational fluid dynamic and reactionkinetic modeling

《化学科学与工程前沿(英文)》 2022年 第16卷 第7期   页码 1149-1163 doi: 10.1007/s11705-021-2096-0

摘要: The production of solar fuels via the photoreduction of carbon dioxide to methane by titanium oxide is a promising process to control greenhouse gas emissions and provide alternative renewable fuels. Although several reaction mechanisms have been proposed, the detailed steps are still ambiguous, and the limiting factors are not well defined. To improve our understanding of the mechanisms of carbon dioxide photoreduction, a multiphysics model was developed using COMSOL. The novelty of this work is the computational fluid dynamic model combined with the novel carbon dioxide photoreduction intrinsic reaction kinetic model, which was built based on three-steps, namely gas adsorption, surface reactions and desorption, while the ultraviolet light intensity distribution was simulated by the Gaussian distribution model and Beer-Lambert model. The carbon dioxide photoreduction process conducted in a laboratory-scale reactor under different carbon dioxide and water moisture partial pressures was then modeled based on the intrinsic kinetic model. It was found that the simulation results for methane, carbon monoxide and hydrogen yield match the experiments in the concentration range of 10−4 mol·m–3 at the low carbon dioxide and water moisture partial pressure. Finally, the factors of adsorption site concentration, adsorption equilibrium constant, ultraviolet light intensity and temperature were evaluated.

关键词: carbon dioxide photoreduction     computational fluid dynamic simulation     kinetic model     Langmuir adsorption    

Kinetic study of hydrodesulfurization of coker gas oil in a slurry reactor

Haiding XIANG, Tiefeng WANG

《化学科学与工程前沿(英文)》 2013年 第7卷 第2期   页码 139-144 doi: 10.1007/s11705-013-1323-8

摘要: Coker gas oil (CGO) is a poor-quality feedstock for fluidized bed catalytic cracking (FCC) or hydrocracking. The pretreatment of CGO, especially hydrotreating, can significantly improve the product quality and protect the catalyst. In this work, we studied the hydrodesulfurization (HDS) of CGO in a slurry reactor. All the experiments were carried out in an autoclave using a NiMo/Al O catalyst at reaction temperature 340°C–400°C, pressure 6–10 MPa, and stirring speed 800 r·min , with hydrogen-to-oil ratio in the range of 500–1500. The effects of the operating parameters on the desulfurization ratio were investigated and discussed. A macro reaction kinetic model was established for the HDS of CGO in the slurry reactor.

关键词: coker gas oil     hydrodesulfurization     slurry reactor     reaction kinetic model    

Kinetic model for hydroisomerization reaction of C-aromatics

XU Ouguan, SU Hongye, JIN Xiaoming, CHU Jian

《化学科学与工程前沿(英文)》 2008年 第2卷 第1期   页码 10-16 doi: 10.1007/s11705-008-0015-2

摘要: Based on the reported reaction networks, a novel six-component hydroisomerization reaction network with a new lumped species including C-naphthenes and C-paraffins is proposed and a kinetic model for a commercial unit is also developed. An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke formation on the catalyst surface during the long-term operation. The Runge-Kutta method is used to solve the ordinary differential equations of the model. The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimization method (BFGS). The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predictions and the plant observations.

关键词: ordinary differential     Runge-Kutta     catalyst deactivation     C-paraffins     optimization    

Reaction kinetics of CaC

Renxing Wang,Zhenyu Liu,Leiming Ji,Xiaojin Guo,Xi Lin,Junfei Wu,Qingya Liu

《化学科学与工程前沿(英文)》 2016年 第10卷 第4期   页码 517-525 doi: 10.1007/s11705-016-1585-z

摘要: The production of CaC from coke/lime powders and compressed powder pellets are low cost and fast processes. A number of studies have reported the reaction kinetics of these reactions but they are still not well understood and the proposed kinetic models are not comparable due to differences in the reaction conditions. Therefore the reaction behavior of CaO/C powders (0.074 mm) and cubes (5 mm × 5 mm × (4.6–5.1) mm) compressed from a mixture of powders have been studied using thermal gravimetric analysis (TGA) at 1700– 1850 °C. Kinetic models were obtained from the TGA data using isoconversional and model-fitting methods. The reaction rates for the compressed feeds were lower than those for the powder feeds. This is due to the reduced surface area of the compressed samples which inhibits heat transfer from the surrounding environment (or the heating source) to the sample. The compression pressure had little influence on the reaction rate. The reaction kinetics of both the powder and the compressed feeds can be described by the contracting volume model ( ) = 3(1− ) , where is the conversion rate of reactant. The apparent activation energy and pre-exponential factor of the powder feed were estimated to 346–354 kJ?mol and 5.9 × 10 min , respectively, whereas those of the compressed feed were 305–327 kJ?mol and 3.6 × 10 min , respectively.

关键词: calcium carbide     kinetic model     activation energy     pre-exponential factor    

Kinetic energy based model assessment and sensitivity analysis of vortex induced vibration of segmental

Nazim Abdul NARIMAN

《结构与土木工程前沿(英文)》 2017年 第11卷 第4期   页码 480-501 doi: 10.1007/s11709-017-0435-5

摘要: In this paper, semi 3D models for segmental Bridge decks are created in ABAQUS CFD program with the support of MATLAB codes to simulate and analyze vortex shedding generated due to wind excitation through considering the stationary position of the deck. Three parameters (wind speed, deck streamlined length and dynamic viscosity of the air) are dedicated to study their effects on the kinetic energy of the system in addition to the shapes and patterns of the vortices. Two benchmarks from the literature Von Karman and Dyrbye and Hansen are considered to validate the vortex shedding aspects for the CFD models. Good agreement between the results of the benchmarks and the semi 3D models has been detected. Latin hypercube experimental method is dedicated to generate the surrogate models for the kinetic energy of the system and the lift forces. Variance based sensitivity analysis is utilized to calculate the main sensitivity indices and the interaction orders for all the three parameters. The kinetic energy approach performed very well in revealing the rational effects and the roles of each parameter in the generation of vortex shedding and predicting vortex induced vibration of the deck.

关键词: vortex induced vibration     reynolds number     kinetic energy     vorticity     latin hypercube sampling    

Oxidation-extraction desulfurization of model oil over Zr-ZSM-5/SBA-15 and kinetic study

Chuanzhu LU,Hui FU,Huipeng LI,Hua ZHAO,Tianfeng CAI

《化学科学与工程前沿(英文)》 2014年 第8卷 第2期   页码 203-211 doi: 10.1007/s11705-014-1420-3

摘要: ZSM-5/SBA-15 composite molecular sieves were synthesized using post-synthesis method and characterized by X-ray diffraction and N adsorption-desorption. The oxidative-extration desulfurization of model oil was investigated by using hydrogen peroxide as the oxidant, tetrabutyl ammonium bromide as phase transfer catalyst, dimethyl sulfoxide as extractant, and Zr-ZSM-5/SBA-15, Ag-ZSM-5/SBA-15, Ce-ZSM-5/SBA-15 as catalyst. Under the optimal conditions, the desulfurization rate decreases in the order: Zr-ZSM-5/SBA-15>Ce-ZSM-5/SBA-15>Ag-ZSM-5/SBA-15. The highest desulfurization rate is 84.53% under the catalysis of Zr-ZSM-5/SBA-15. Kinetics analysis shows that the reaction is pseudo-first-order with the activation energy of 44.23 kJ/mol.

关键词: composite molecular sieve     oxidation desulfuration     extraction     kinetic    

Experimental and kinetic study on laminar flame speeds of ammonia/syngas/air at a high temperature and

《能源前沿(英文)》 2022年 第16卷 第2期   页码 263-276 doi: 10.1007/s11708-021-0791-7

摘要: The laminar flame speeds of ammonia mixed with syngas at a high pressure, temperature, and different syngas ratios were measured. The data obtained were fitted at different pressures, temperatures, syngas ratios, and equivalence ratios. Four kinetic models (the Glarborg model, Shrestha model, Mei model, and Han model) were compared and validated with experimental data. Pathway, sensitivity and radical pool analysis are conducted to find out the deep kinetic insight on ammonia oxidation and NO formation. The pathway analysis shows that H abstraction reactions and NHi combination reactions play important roles in ammonia oxidation. NO formation is closely related to H, OH, the O radical produced, and formation reactions. NO is mainly formed from reaction, HNO+ H= NO+ H2. Furthermore, both ammonia oxidation and NO formation are sensitive to small radical reactions and ammonia related reactions.

关键词: ammonia mixed with syngas     laminar flame speed     kinetic model     sensitivity analysis     pathway analysis    

Diffusion process in enzyme–metal hybrid catalysts

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 921-929 doi: 10.1007/s11705-022-2144-4

摘要: Enzyme–metal hybrid catalysts bridge the gap between enzymatic and heterogeneous catalysis, which is significant for expanding biocatalysis to a broader scope. Previous studies have demonstrated that the enzyme–metal hybrid catalysts exhibited considerably higher catalytic efficiency in cascade reactions, compared with that of the combination of separated enzyme and metal catalysts. However, the precise mechanism of this phenomenon remains unclear. Here, we investigated the diffusion process in enzyme–metal hybrid catalysts using Pd/lipase-Pluronic conjugates and the combination of immobilized lipase (Novozyme 435) and Pd/C as models. With reference to experimental data in previous studies, the Weisz–Prater parameter and efficiency factor of internal diffusion were calculated to evaluate the internal diffusion limitations in these catalysts. Thereafter, a kinetic model was developed and fitted to describe the proximity effect in hybrid catalysts. Results indicated that the enhanced catalytic efficiency of hybrid catalysts may arise from the decreased internal diffusion limitation, size effect of Pd clusters and proximity of the enzyme and metal active sites, which provides a theoretical foundation for the rational design of enzyme–metal hybrid catalysts.

关键词: enzyme–metal hybrid catalyst     internal diffusion     proximity effect     kinetic model    

Recovery of NH

Yang ZHANG,Zifu LI,Ibrahim B MAHMOOD

《环境科学与工程前沿(英文)》 2014年 第8卷 第6期   页码 825-834 doi: 10.1007/s11783-014-0682-9

摘要: ion, a main pollutant in aquatic systems, not only causes eutrophication in rivers and lakes but also contributes to fish toxicity. In this study, an eco-friendly biosorbent was prepared from the pyrolysis of corn cob, a low-cost agricultural residue. The biochars produced by pyrolysis of corn cob at 400°C and 600°C were characterized and investigated as adsorbents for from an aqueous solution. The biochars were characterized through elemental analysis, Brunauer–Emmett–Teller–N surface area analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. Batch experiments were conducted to investigate the adsorption process of the corn cob biochars. The Freundlich isotherm model fitted the adsorption process better than the Langmuir and Dubinin–Radushkevich isotherm models. Moreover, the adsorption process was well described by a pseudo-second-order kinetic model. Results of thermodynamic analysis suggested that adsorption was a nonspontaneous exothermic process. Biochars produced at 400°C had higher adsorption capacity than those produced at 600°C because of the presence of polar functional groups with higher acidity. The exhausted biochar can be potentially used as soil conditioner, which can provide 6.37 kg (N fertilizer per ton of biochar).

关键词: corn cob     biochar     isotherm model     kinetic model        

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption kinetic

Junxiong LIN , Lan WANG ,

《环境科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 320-324 doi: 10.1007/s11783-009-0030-7

摘要: The best-fit equations of linear and non-linear forms of the two widely used kinetic models, namely pseudo-first-order and pseudo-second-order equations, were compared in this study. The experimental kinetics of methylene blue adsorption on activated carbon was used for this research. Both the correlation coefficient () and the normalized standard deviation Δ(%) were employed as error analysis methods to determine the best-fitting equations. The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data. The experimental kinetics may have been distorted by linearization of the linear kinetic equations, and thus, the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters. In addition, the Δ(%) method for error analysis may be better to determine the best-fitting model in this case.

关键词: adsorption     pseudo-first order     pseudo-second order     kinetic model     linear method     non-linear method    

Electrocoagulation process for the treatment of metal-plating wastewater: Kinetic modeling and energy

Fatih Ilhan, Kubra Ulucan-Altuntas, Yasar Avsar, Ugur Kurt, Arslan Saral

《环境科学与工程前沿(英文)》 2019年 第13卷 第5期 doi: 10.1007/s11783-019-1152-1

摘要: The wastewater from industrial area was treated by EC via Fe and Al electrodes. Cu, Ni, Cr and Zn were highly removed at the first minutes, simultaneously. Pseudo-2nd-order was found to be more suitable for kinetics. Adsorption capacities based on kinetic modeling were observed as Cr>Cu>Ni>Zn. The chemical cost in the case of pH adjustment after EC was less as 3.83 $/m3. It is known that wastewater produced by the metal-plating industry contains several heavy metals, which are acidic in nature and therefore toxic for the environment and for living creatures. In particular, heavy metals enter the food chain and accumulate in vital organs and cause serious illness. The precipitation of these metals is mostly achieved by pH adjustment, but as an alternative to this method, the electrocoagulation process has investigated in this study using iron and aluminum electrodes. The effects of the pH adjustment on removal before and after the electrocoagulation process were investigated, and cost analyses were also compared. It was observed that a high proportion of removal was obtained during the first minutes of the electrocoagulation process; thus, the current density did not have a great effect. In addition, the pH adjustment after the electrocoagulation process using iron electrodes, which are 10% more effective than aluminum electrodes, was found to be much more efficient than before the electrocoagulation process. In the process where kinetic modeling was applied, it was observed that the heavy metal removal mechanism was not solely due to the collapse of heavy metals at high pH values, and with this modeling, it was seen that this mechanism involved adsorption by iron and aluminum hydroxides formed during the electrocoagulation process. When comparing the ability of heavy metals to be adsorbed, the sequence was observed to be Cr>Cu>Ni>Zn, respectively.

关键词: Electrochemical treatment     Heavy metals     Kinetic modeling     Pseudo first order kinetic     Pseudo second order kinetic    

Modified landfill gas generation rate model of first-order kinetics and two-stage reaction

Jiajun CHEN , Hao WANG , Na ZHANG ,

《环境科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 313-319 doi: 10.1007/s11783-009-0025-4

摘要: This investigation was carried out to establish a new domestic landfill gas (LFG) generation rate model that takes into account the impact of leachate recirculation. The first-order kinetics and two-stage reaction (FKTSR) model of the LFG generation rate includes mechanisms of the nutrient balance for biochemical reaction in two main stages. In this study, the FKTSR model was modified by the introduction of the outflow function and the organic acid conversion coefficient in order to represent the in-situ condition of nutrient loss through leachate. Laboratory experiments were carried out to simulate the impact of leachate recirculation and verify the modified FKTSR model. The model calibration was then calculated by using the experimental data. The results suggested that the new model was in line with the experimental data. The main parameters of the modified FKTSR model, including the LFG production potential (), the reaction rate constant in the first stage (), and the reaction rate constant in the second stage () of 64.746 L, 0.202 d, and 0.338 d, respectively, were comparable to the old ones of 42.069 L, 0.231 d, and 0.231 d. The new model is better able to explain the mechanisms involved in LFG generation.

关键词: landfill gas (LFG)     generation rate model     first-order kinetics     two-stage reaction     outflow function    

Effect of adjusted mesoscale drag model on flue gas desulfurization in powder-particle spouted beds

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 909-920 doi: 10.1007/s11705-021-2100-8

摘要: An energy minimum multiscale model was adjusted to simulate the mesoscale structure of the flue gas desulfurization process in a powder-particle spouted bed and verified experimentally. The obtained results revealed that the spout morphology simulated by the adjusted mesoscale drag model was unstable and discontinuous bubbling spout unlike the stable continuous spout obtained using the Gidaspow model. In addition, more thorough gas radial mixing was achieved using the adjusted mesoscale drag model. The mass fraction of water in the gas mixture at the outlet determined by the heterogeneous drag model was 1.5 times higher than that obtained by the homogeneous drag model during the simulation of water vaporization. For the desulfurization reaction, the experimental desulfurization efficiency was 75.03%, while the desulfurization efficiencies obtained by the Gidaspow and adjusted mesoscale drag models were 47.63% and 75.08%, respectively, indicating much higher accuracy of the latter technique.

关键词: adjusted mesoscale drag model     particle image velocimetry     water vaporization     desulfurization reaction     numerical simulation    

Catalytic process modeling and sensitivity analysis of alkylation of benzene with ethanol over MIL-101(Fe) and MIL-88(Fe)

Ehsan Rahmani, Mohammad Rahmani

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 1100-1111 doi: 10.1007/s11705-019-1891-3

摘要: A solvothermal method was used to synthesize MIL-101(Fe) and MIL-88(Fe), which were used for alkylation of benzene. The synthesized catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, dynamic light scattering, and BET techniques. Metal-organic frameworks (MOFs) were modeled to investigate the catalytic performance and existence of mass transfer limitations. Calculated effectiveness factors revealed absence of internal and external mass transfer. Sensitivity analysis revealed best operating conditions over MIL-101 at 120°C and 5 bar and over MIL-88 at 142°C and 9 bar.

关键词: MOFs     alkylation     ethylbenzene     catalysts pellet model     kinetic model     sensitivity analysis    

Effects of nitrate concentration on biological hydrogen production by mixed cultures

Bo WANG, Wei WAN, Jianlong WANG,

《环境科学与工程前沿(英文)》 2009年 第3卷 第4期   页码 380-386 doi: 10.1007/s11783-009-0142-0

摘要: The effects of nitrate on fermentative hydrogen production and soluble metabolites from mixed cultures were investigated by varying nitrate concentrations from 0 to 10g N/L at 35°C with an initial pH of 7.0. The results showed that the substrate degradation rate, hydrogen production potential, hydrogen yield, and average hydrogen production rate initially increased with increasing nitrate concentrations from 0 to 0.1g N/L, while they decreased with increasing nitrate concentrations from 0.1 to 10g N/L. The maximum hydrogen production potential of 305.0mL, maximum hydrogen yield of 313.1mL/g glucose, and maximum average hydrogen production rate of 13.3mL/h were obtained at a nitrate concentration of 0.1g N/L. The soluble metabolites produced by the mixed cultures contained only ethanol and acetic acid (HAc) without propionic acid (HPr) and butyric acid (HBu). This study used the Modified Logistic model to describe the progress of cumulative hydrogen production in batch tests. A concise model was proposed to describe the effects of nitrate concentration on average hydrogen production rate.

关键词: nitrogen source     biohydrogen     fermentative hydrogen production     quantitative kinetic model    

标题 作者 时间 类型 操作

dioxide photoreduction process in a laboratory-scale photoreactor by computational fluid dynamic and reactionkinetic modeling

期刊论文

Kinetic study of hydrodesulfurization of coker gas oil in a slurry reactor

Haiding XIANG, Tiefeng WANG

期刊论文

Kinetic model for hydroisomerization reaction of C-aromatics

XU Ouguan, SU Hongye, JIN Xiaoming, CHU Jian

期刊论文

Reaction kinetics of CaC

Renxing Wang,Zhenyu Liu,Leiming Ji,Xiaojin Guo,Xi Lin,Junfei Wu,Qingya Liu

期刊论文

Kinetic energy based model assessment and sensitivity analysis of vortex induced vibration of segmental

Nazim Abdul NARIMAN

期刊论文

Oxidation-extraction desulfurization of model oil over Zr-ZSM-5/SBA-15 and kinetic study

Chuanzhu LU,Hui FU,Huipeng LI,Hua ZHAO,Tianfeng CAI

期刊论文

Experimental and kinetic study on laminar flame speeds of ammonia/syngas/air at a high temperature and

期刊论文

Diffusion process in enzyme–metal hybrid catalysts

期刊论文

Recovery of NH

Yang ZHANG,Zifu LI,Ibrahim B MAHMOOD

期刊论文

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption kinetic

Junxiong LIN , Lan WANG ,

期刊论文

Electrocoagulation process for the treatment of metal-plating wastewater: Kinetic modeling and energy

Fatih Ilhan, Kubra Ulucan-Altuntas, Yasar Avsar, Ugur Kurt, Arslan Saral

期刊论文

Modified landfill gas generation rate model of first-order kinetics and two-stage reaction

Jiajun CHEN , Hao WANG , Na ZHANG ,

期刊论文

Effect of adjusted mesoscale drag model on flue gas desulfurization in powder-particle spouted beds

期刊论文

Catalytic process modeling and sensitivity analysis of alkylation of benzene with ethanol over MIL-101(Fe) and MIL-88(Fe)

Ehsan Rahmani, Mohammad Rahmani

期刊论文

Effects of nitrate concentration on biological hydrogen production by mixed cultures

Bo WANG, Wei WAN, Jianlong WANG,

期刊论文