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SCI和EI收录∣中国化工学会会刊
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Table of Content
28 September 2020, Volume 28 Issue 9
    Review
    The synthetic strategies of hierarchical TS-1 zeolites for the oxidative desulfurization reactions
    Guoju Yang, Ji Han, Yue Liu, Ziyi Qiu, Xiaoxin Chen
    2020, 28(9):  2227-2234.  doi:10.1016/j.cjche.2020.06.026
    Abstract ( 220 )   PDF (3907KB) ( 246 )  
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    With the increasingly stringent standards for limiting sulfide content in liquid fuels, oxidative desulfurization (ODS) has become a promising ultra-deep desulfurization process in fuel desulfurization. TS-1 zeolites show great potential as catalysts for ODS reactions, due to its remarkable oxidation activity at low temperatures and pressure. However, the inherent microporous structure of conventional TS-1 zeolites restricts the mass transportation and renders the active sites in the microporous space of TS-1 zeolites inaccessible for bulky aromatic organosulfur compounds. Fabrication of hierarchical TS-1 zeolites by incorporating meso-/macropores into microporous TS-1 zeolites is an effective strategy to improve mass transportability. In recent years, abundant efforts have been dedicated to developing synthetic strategies of hierarchical TS-1 zeolite, thereby improving its catalytic performance in the ODS process. This mini-review addresses the synthetic methods of hierarchical TS-1 catalysts and their catalytic performance in the ODS reactions. In addition, some current problems and prospects of synthesis routes for constructing hierarchical TS-1 catalysts have also been revised. We expect this mini-review to shed light on the more efficient preparation strategies of hierarchical TS-1 zeolites for the ODS process.
    Fluid Dynamics and Transport Phenomena
    Numerical simulation of micro-mixing in gas-liquid and solid-liquid stirred tanks with the coupled CFD-E-model
    Xiaoxia Duan, Xin Feng, Chong Peng, Chao Yang, Zaisha Mao
    2020, 28(9):  2235-2247.  doi:10.1016/j.cjche.2020.06.016
    Abstract ( 222 )   PDF (3970KB) ( 178 )  
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    The coupled CFD-E-model for multiphase micro-mixing was developed, and used to predict the micro-mixing effects on the parallel competing chemical reactions in semi-batch gas-liquid and solid-liquid stirred tanks. Based on the multiphase macro-flow field, the key parameters of the micro-mixing E-model were obtained with solving the Reynolds-averaged transport equations of mixture fraction and its variance at low computational costs. Compared with experimental data, the multiphase numerical method shows the satisfactory predicting ability. For the gas-liquid system, the segregated reaction zone is mainly near the feed point, and shrinks to the exit of feed-pipe when the feed position is closer to the impeller. Besides, surface feed requires more time to completely exhaust the added H+ solution than that of impeller region feed at the same operating condition. For the solid- liquid system, when the solid suspension cloud is formed at high solid holdups, the flow velocity in the clear liquid layer above the cloud is notably reduced and the reactions proceed slowly in this almost stagnant zone. Therefore, the segregation index in this case is larger than that in the dilute solid-liquid system.
    Separation Science and Engineering
    Integrated UV-based photo microreactor-distillation technology toward process intensification of continuous ultra-high-purity electronic-grade silicon tetrachloride manufacture
    Ye Wan, Wenhui Guo, Jin Xiao, Dazhou Yan, Xiong Zhao, Shuhu Guo, Jianhua Liu, Qifan Zhong, Tao Yang, Yu Zhao, Xin Chang, Xin Gao
    2020, 28(9):  2248-2255.  doi:10.1016/j.cjche.2020.06.023
    Abstract ( 173 )   PDF (1639KB) ( 178 )  
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    Ultra-high-purity silicon tetrachloride (SiCl4) is demanded as an electronic-grade chemical to meet the stringent requirements of the rapidly developing semiconductor industry. The high requirement for ultra-high-purity SiCl4 has created the need for a high-efficient process for reducing energy consumption as well as satisfying product quality. In this paper, a mass of production technology of ultra-high-purity SiCl4 was successfully developed through chlorination reaction in the ultraviolet (UV)-based photo microreactor coupled with the distillation process. The influences of key operational parameters, including temperature, pressure, UV wavelength and light intensity on the product quality, especially for hydrogen-containing impurities, were quantified by the infrared transmittance of Fourier transform infrared spectroscopy (FT-IR) at 2185 cm-1 and 2160 cm-1 indicating that characteristic vibrational modes of Si—H bonds, as well as the operating conditions of distillation were also investigated as key factors for metal impurities removing. The advanced intensification of SiCl4 manufactured by the integration of photo microreactor and distillation achieves the products with superior specifications higher than the standard commercial products.
    Simultaneous preparation of TiO2 and ammonium alum, and microporous SiO2 during the mineral carbonation of titanium-bearing blast furnace slag
    Yingjie Xiong, Tahani Aldahri, Weizao Liu, Guanrun Chu, Guoquan Zhang, Dongmei Luo, Hairong Yue, Bin Liang, Chun Li
    2020, 28(9):  2256-2266.  doi:10.1016/j.cjche.2020.03.020
    Abstract ( 210 )   PDF (2103KB) ( 131 )  
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    In this study, a route for simultaneous mineralization of CO2 and production of titanium dioxide and ammonium alum, and microporous silicon dioxide from titanium-bearing blast furnace slag (TBBF slag) was proposed, which is comprised of (NH4)2SO4 roasting, acid leaching, ammonium alum crystallization, silicic acid flocculation and Ti hydrolysis. The effects of relevant process parameters were systematically investigated. The results showed that under the optimal roasting and leaching conditions about 85% of titanium and 84.6% of aluminum could be extracted while only 30% of silicon entered the leachate. 84% of Al3+ was crystallized from the leachate in the form of ammonium aluminum sulfate dodecahydrate with a purity up to 99.5 wt%. About 85% of the soluble silicic acid was flocculated with the aid of secondary alcohol polyoxyethylene ether 9 (AEO-9) to yield a microporous SiO2 material (97.4 wt%) from the crystallized mother liquor. The Al- and Si-depleted solution was then hydrolyzed to generate a titanium dioxide (99.1 wt%) with uniform particle size distribution. It was figured out that approximately 146 kg TiO2 could be produced from 1000 kg of TBBF slag. Therefore, the improved process is a promising method for industrial application.
    The effect of ZIF-90 particle in Pebax/Psf composite membrane on the transport properties of CO2, CH4 and N2 gases by Molecular Dynamics Simulation method
    Ali Hatami, Iman Salahshoori, Niloufar Rashidi, Danial Nasirian
    2020, 28(9):  2267-2284.  doi:10.1016/j.cjche.2019.12.011
    Abstract ( 199 )   PDF (13562KB) ( 42 )  
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    Nowadays, mixed matrix membranes (MMMs) have considered by many researchers to overcome the problems of polymeric membranes. In addition, molecular dynamics (MD) and Monte Carlo (MC) simulation Methods are suitable tools for studying transport properties and morphology in MMMs. For this purpose, in this study using material studio 2017 (MS) software, the transport properties of CO2, CH4 and N2 in Pebax, Psf neat Pebax/Psf composite and Pebax/Psf composite filled with ZIF-90 particles have been investigated. By adding Psf to Pebax matrix, the selectivity of CO2/CH4 and CO2/N2 gases has significantly increased. In addition, adding ZIF-90 particles to the Pebax/Psf composite increased the permeability of CO2, CH4 and N2 compared to neat and composite membranes. The morphological properties of the membranes, such as the fractional free volume (FFV), radial distribution function (RDF), glass transition temperature (TG), X-ray diffraction (XRD) and equilibrium density have calculated and acceptable results have obtained.
    A computational simulation study for techno-economic comparison of conventional and stripping gas methods for natural gas dehydration
    Muhammad Salman, Liangliang Zhang, Jianfeng Chen
    2020, 28(9):  2285-2293.  doi:10.1016/j.cjche.2020.03.013
    Abstract ( 138 )   PDF (1504KB) ( 205 )  
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    In the present work, the conventional natural gas dehydration method (CDM) and stripping gas method (SGM) are technically and economically analyzed, utilizing Aspen HYSYS and Aspen Process Economic Analyzer (APEA), respectively. To optimize the CDM and SGM, the sensitivities of the water content of dry gas, reboiler duty and raw material loss are analyzed against solvent rate and stripping gas rate. The optimized processes are set to achieve a targeted value of water content in dry gas and analyzed at optimized point. The analysis shows that SGM gives 46% lower TEG feed rate, 42% lower reboiler duty and 99.97% pure regenerated TEG. Moreover, economic analysis reveals that SGM has 38% lower annual operating cost compared to CDM. According to results, from both technical and economic point of view, SGM is more feasible for natural gas dehydration compared to CDM.
    Application of hydrophobic ionic liquid [Bmmim][PF6] in solvent extraction for oily sludge
    Lingfu Zhu, Zuhong Lin, Jie Tan, Liyang Hu, Tingting Zhang
    2020, 28(9):  2294-2300.  doi:10.1016/j.cjche.2020.03.014
    Abstract ( 108 )   PDF (1590KB) ( 45 )  
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    In this study, an ionic liquid (IL), 1-butyl-2,3-dimmmethylimidazolium hexafluorophosphate ([Bmmim][PF6]), was used in combination with a composite solvent of methyl acetate and n-heptane to enhance the oil extraction from oily sludge. The oil recovery increased by approximately 15% compared with that of solvent extraction without [Bmmim][PF6] at the optimal ratios of IL to sludge and solvents to sludge, which were at 2:5 (M/M) and 4:1 (V/M), respectively. The saturate, aromatic, resin and asphaltene (SARA) analysis revealed that the recovery of resins and asphaltenes was increased by 14% and 38%, respectively, in the solvent extraction with the addition of [Bmmim][PF6]. [Bmmim][PF6] maintained a good performance after its reuse four times. The addition of [Bmmim][PF6] changed the adhesion forces between oil and soil. The IL-assisted solvent extraction procedure followed the pseudo second-order kinetic model, while the unassisted solvent extraction procedure followed the pseudo first-order kinetic model. The results also demonstrated that [Bmmim][PF6] decreased the solvent consumption by approximately 60% each time. Additionally, [Bmmim][PF6] can be easily separated. The results suggested that enhancing the solvent extraction with this IL is a promising way to recover oil from oily sludge with a higher oil recovery rate and lower organic solvent consumption than those with the unassisted solvent extraction method.
    New high permeable polysulfone/ionic liquid membrane for gas separation
    Mohadeseh Farrokhara, Fatereh Dorosti
    2020, 28(9):  2301-2311.  doi:10.1016/j.cjche.2020.04.002
    Abstract ( 140 )   PDF (4249KB) ( 168 )  
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    In this study, the effects of 1-Ethyl-3-methylimidazolium tetrafluoroborate ionic liquid on CO2/CH4 separation performance of symmetric polysulfone membranes are investigated. Pure polysulfone membrane and ionic liquid-containing membranes are characterized. Field emission scanning electron microscopy (FE-SEM) is used to analyze surface morphology and thickness of the fabricated membranes. Energy dispersive spectroscopy (EDS) and elemental mapping, Fourier transform infrared (FTIR), thermal gravimetric (TGA), X-ray diffraction (XRD) and Tensile strength analyses are also conducted to characterize the prepared membranes. CO2/CH4 separation performance of the membranes are measured twice at 0.3 MPa and room temperature (25 °C). Permeability measurements confirm that increasing ionic liquid content in polymer-ionic liquid membranes leads to a growth in CO2 permeation and CO2/CH4 selectivity due to high affinity of the ionic liquid to carbon dioxide. CO2 permeation significantly increases from 4.3 Barrer (1 Barrer=10-10 cm3(STP)·cm·cm-2·s-1·cmHg-1, 1cmHg=1.333kPa) for the pure polymer membrane to 601.9 Barrer for the 30 wt% ionic liquid membrane. Also, selectivity of this membrane is improved from 8.2 to 25.8. mixed gas tests are implemented to investigate gases interaction. The results showed, the disruptive effect of CH4 molecules for CO2 permeation lead to selectivity decrement compare to pure gas test. The fabricated membranes with high ionic liquid content in this study are promising materials for industrial CO2/CH4 separation membranes.
    Preparation and evaluation of α-Al2O3 supported lithium ion sieve membranes for Li+ extraction
    Feng Xue, Xiaoxian Zhang, Yue Niu, Chenhao Yi, Shengui Ju, Weihong Xing
    2020, 28(9):  2312-2318.  doi:10.1016/j.cjche.2020.05.006
    Abstract ( 123 )   PDF (1050KB) ( 84 )  
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    Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li+ from brines and sea water. Here, we report a lithium ion-sieve which was successfully loaded onto tubular α-Al2O3 ceramic substrates by dipping crystallization and post-calcination method. The lithium manganese oxide Li4Mn5O12 was first synthesized onto tubular α-Al2O3 ceramic substrates as the ion-sieve precursor (i.e. L-AA), and the corresponding lithium ion-sieve (i.e. H-AA) was obtained after acid pickling. The chemical and morphological properties of the ion-sieve were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Both L-AA and H-AA showed characteristic peaks of α-Al2O3 and cubic phase Li4Mn5O12, and the peaks representing cubic phase could still exist after pickling. The lithium manganese oxide Li4Mn5O12 could be uniformly loaded not only on the surface of α-Al2O3 substrates but also inside the pores. Moreover, we found that the equilibrium adsorption capacity of H-AA was 22.9 mg·g-1. After 12 h adsorption, the adsorption balance was reached. After 5 cycles of adsorption, the adsorption capacity of H-AA was 60.88% of the initial adsorption capacity. The process of H-AA adsorption for Li+ correlated with pseudo-second order kinetic model and Langmuir model. Adsorption thermodynamic parameters regarding enthalpy (ΔH), Gibbs free energy (ΔG) and entropy (ΔS) were calculated. For the dynamic adsorption- desorption process of H-AA, the H-AA exhibited excellent adsorption performance to Li+ with the Li+ dynamic adsorption capacity of 9.74 mg·g-1 and the Mn2+ dissolution loss rate of 0.99%. After 3 dynamic adsorption-desorption cycles, 80% of the initial dynamic adsorption capacity was still kept.
    Catalysis, Kinetics and Reaction Engineering
    Structured hierarchical Mn-Co mixed oxides supported on silicalite-1 foam catalyst for catalytic combustion
    Yanan Guan, Hengyu Shen, Xing Guo, Boyang Mao, Zhenyuan Yang, Yangtao Zhou, He Liang, Xiaolei Fan, Yilai Jiao, Jinsong Zhang
    2020, 28(9):  2319-2327.  doi:10.1016/j.cjche.2020.06.019
    Abstract ( 128 )   PDF (3625KB) ( 78 )  
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    Silicalite-1 (S1) foam was functionalized by supporting manganese-cobalt (Mn-Co) mixed oxides to develop the structured hierarchical catalyst (Mn-Co@S1F) for catalytic combustion for the first time. The self-supporting S1 foam with hierarchical porosity was prepared via hydrothermal synthesis with polyurethane (PU) foam as the template. Subsequently, Mn-Co oxide nano sheets were uniformly grown on the surface of S1 foams under hydrothermal conditions to prepare the structured hierarchical catalyst with specific surface area of 354 m2·g-1, micropore volume of 0.141 cm3·g-1 and total pore volume of 0.217 cm3·g-1, as well as a good capacity to adsorb toluene (1.7 mmol·g-1 at p/p0 = 0.99). Comparative catalytic combustion of toluene of over developed structured catalyst Mn-Co@S1F was performed against the control catalysts of bulk Mn-Co@S1 (i.e., the crushed Mn-Co@S1F) and unsupported Mn-Co oxides (i.e., Mn-Co). Mn-Co@S1F exhibited comparatively the best catalytic performance, that is, complete and stable toluene conversion at 248 °C over 65 h due to the synergy between Mn-Co oxides and S1 foam, which provided a large number of oxygen vacancies, high redox capacity. In addition, the hierarchical porous structure also improved the accessibility of active sites and facilitated the global mass transfer across the catalyst bed, being beneficial to the catalysis and catalyst longevity.
    Renewable hydrogen production from steam reforming of glycerol (SRG) over ceria-modified γ-alumina supported Ni catalyst
    Ammaru Ismaila, Huanhao Chen, Yan Shao, Shaojun Xu, Yilai Jiao, Xueli Chen, Xin Gao, Xiaolei Fan
    2020, 28(9):  2328-2336.  doi:10.1016/j.cjche.2020.06.025
    Abstract ( 163 )   PDF (3178KB) ( 113 )  
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    Excess crude glycerol derived as a by-product from biodiesel industry prompts the need to valorise glycerol to value-added chemicals. In this context, catalytic steam reforming of glycerol (SRG) was proposed as a promising and sustainable alternative for producing renewable hydrogen (H2). Herein, the development of nickel (Ni) supported on ceria-modified mesoporous γ-alumina (γ-Al2O3) catalysts and their applications in catalytic SRG (at 550-750 °C, atmospheric pressure and weight hourly space velocity, WHSV, of 44,122 ml·g-1·h-1 (STP)) is presented. Properties of the developed catalysts were characterised using many techniques. The findings show that ceria modification improved Ni dispersion on γ-Al2O3 catalyst support with highly active small Ni particles, which led to a remarkable catalytic performance with the total glycerol conversion (ca. 99%), glycerol conversion into gaseous products (ca. 77%) and H2 yield (ca. 62%). The formation rate for H2 production (14.4 × 10-5 mol·s-1·g-1, TOF (H2) = 3412 s-1) was significantly improved with the Ni@12Ce-Al2O3 catalyst, representing nearly a 2-fold increase compared with that of the conventional Ni@Al2O3 catalyst. In addition, the developed catalyst also exhibited comparatively high stability (for 12 h) and coke resistance ability.
    Dehydrogenation of methylcyclohexane over Pt supported on Mg-Al mixed oxides catalyst: The effect of promoter Ir
    Lei Miao, Jing Yan, Weiyan Wang, Yanping Huang, Wensong Li, Yunquan Yang
    2020, 28(9):  2337-2342.  doi:10.1016/j.cjche.2020.05.026
    Abstract ( 136 )   PDF (1488KB) ( 219 )  
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    To enhance the hydrogen release during hydrogen storage, several Pt-Ir supported on Mg-Al mixed oxide catalysts were prepared and then applied into the dehydrogenation of methylcyclohexane (MCH) in this study. The effects of iridium content, reduction temperature on the activity and stability of the catalysts were studied in detail. In the presence of Ir, metal particle size was decreased and electron transfer between Ir and Pt was observed. High reduction temperature increased the metallic Ir content but enlarged the particle size of active sites. During the dehydrogenation reaction on Pt-Ir bimetallic catalyst, MCH was efficiently converted into toluene and PtIr-5/ Mg-Al-275 exhibited the highest activity. After prolonging the residence time and raising the reaction temperature to 350 °C, the conversion and hydrogen evolution rate were increased to 99.9% and 578.7 mmol·(g Pt)-1·min-1, respectively. Moreover, no carbon deposition was observed in the spent catalyst, presenting a high anti-coking ability and good potential for industrial application.
    Process Systems Engineering and Process Safety
    Gas leakage recognition for CO2 geological sequestration based on the time series neural network
    Denglong Ma, Jianmin Gao, Zhiyong Gao, Hongquan Jiang, Zaoxiao Zhang, Juntai Xie
    2020, 28(9):  2343-2357.  doi:10.1016/j.cjche.2020.06.014
    Abstract ( 131 )   PDF (8648KB) ( 50 )  
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    The leakage of stored and transported CO2 is a risk for geological sequestration technology. One of the most challenging problems is to recognize and determine CO2 leakage signal in the complex atmosphere background. In this work, a time series model was proposed to forecast the atmospheric CO2 variation and the approximation error of the model was utilized to recognize the leakage. First, the fitting neural network trained with recently past CO2 data was applied to predict the daily atmospheric CO2. Further, the recurrent nonlinear autoregressive with exogenous input (NARX) model was adopted to get more accurate prediction. Compared with fitting neural network, the approximation errors of NARX have a clearer baseline, and the abnormal leakage signal can be seized more easily even in small release cases. Hence, the fitting approximation of time series prediction model is a potential excellent method to capture atmospheric abnormal signal for CO2 storage and transportation technologies.
    Deep learning technique for process fault detection and diagnosis in the presence of incomplete data
    Cen Guo, Wenkai Hu, Fan Yang, Dexian Huang
    2020, 28(9):  2358-2367.  doi:10.1016/j.cjche.2020.06.015
    Abstract ( 144 )   PDF (2437KB) ( 71 )  
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    In modern industrial processes, timely detection and diagnosis of process abnormalities are critical for monitoring process operations. Various fault detection and diagnosis (FDD) methods have been proposed and implemented, the performance of which, however, could be drastically influenced by the common presence of incomplete or missing data in real industrial scenarios. This paper presents a new FDD approach based on an incomplete data imputation technique for process fault recognition. It employs the modified stacked autoencoder, a deep learning structure, in the phase of incomplete data treatment, and classifies data representations rather than the imputed complete data in the phase of fault identification. A benchmark process, the Tennessee Eastman process, is employed to illustrate the effectiveness and applicability of the proposed method.
    Dynamic analysis and split range control for maximization of operating range of continuous microbial fuel cell
    Ashish Yewale, Ravi Methekar, Shailesh Agrawal
    2020, 28(9):  2368-2381.  doi:10.1016/j.cjche.2020.06.030
    Abstract ( 138 )   PDF (3648KB) ( 89 )  
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    Human development is inherently connected with availability of water and energy. Energy production requires water, whereas water treatment needs energy. On the other hand, microbial fuel cell has capability to produce energy and water simultaneously from waste water or organic matter. In this paper, first principle-based model of variable volume microbial fuel cell is simulated. Hydraulic retention time is selected as the manipulated variable using the study of steady state and dynamic responses. Classical PI and model predictive control strategies are developed for controlling the produced power from the cell, and its performance is tested for servo problem. Settling time for positive and negative set points is found to be 126 and 889 h in case of classical PI and 120 and 750 h in case of linear MPC, respectively along with large increase (three times order of magnitude) in working volume for negative set point. These control challenges are overcome by using split range controller with variable and constant volume microbial fuel cells. The settling time for negative set point is found to be 49 and 21 h for classical PI and linear MPC schemes, respectively, which is significantly lower than using only variable volume microbial fuel cell. Also, there is no increase in the working volume of the constant volume microbial fuel cell. Hence, operating range of the microbial fuel cell is enhanced using split range controller.
    A comparative process simulation study of Ca—Cu looping involving post-combustion CO2 capture
    Xiaoyu Wang, Haibo Zhao, Mingze Su
    2020, 28(9):  2382-2390.  doi:10.1016/j.cjche.2020.06.033
    Abstract ( 119 )   PDF (3885KB) ( 101 )  
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    This work presents a simulation study of several Ca—Cu looping variants with CO2 capture, aiming at both parameter optimization and exergy analysis of these Ca—Cu looping systems. Three kinds of Ca—Cu looping are considered: 1) carbonation-calcination/reduction-oxidation; 2) carbonation-oxidation-calcination/reduction and 3) carbonation/oxidation-calcination/reduction. A conventional Ca looping is also simulated for comparison. The influences of the calcination temperature on the mole fractions of CO2 and CaO at the calciner outlet, the CaCO3 flow rate on the carbonator performance and the Cu/Ca ratio on the calciner performance are analyzed. The second kind of Ca—Cu looping has the highest carbonation conversion. At 1 × 105 Pa and 820 °C, complete decomposition of CaCO3 can be achieved in three Ca—Cu looping systems, while the operation condition of 1 × 105 Pa, 840 °C is required for the conventional Ca looping system. Furthermore, the Cu/Ca molar ratio of 5.13-5.19 is required for the Ca—Cu looping. Exergy analyses show that the maximum exergy destruction occurs in the calciner for the four modes and the second Ca—Cu looping system (i.e., carbonation-oxidation-calcination/reduction) performs the highest exergy efficiency, up to 65.04%, which is about 30% higher than that of the conventional Ca looping.
    Chemical Engineering Thermodynamics
    Thermodynamic modeling and phase diagram prediction of salt lake brine systems. I. Aqueous Mg2+-Ca2+-Cl- binary and ternary systems
    Huan Zhou, Xiaolong Gu, Yaping Dai, Jingjing Tang, Jian Guo, Guangbi Li, Xiaoqin Bai
    2020, 28(9):  2391-2408.  doi:10.1016/j.cjche.2020.03.039
    Abstract ( 183 )   PDF (7475KB) ( 67 )  
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    Salt lake brine is a complex salt-water system under natural environment. Although many models can express the thermodynamic properties and phase equilibrium of electrolyte aqueous solution, the multi-temperature characteristics and predictability are still the goals of model development. In this study, a comprehensive thermodynamic model system is re-established based on the eNRTL model and some improvements: (1) new expression of long-range electrostatic term with symmetrical reference state is proposed to handle the electrolyte solution covering entire concentration range; (2) the temperature dependence of the binary interaction parameters is formulated with a Gibbs Helmholtz expression containing three temperature coefficients, the liquid parameters, which associated with Gibbs energy, enthalpy, and heat capacity contribution; and (3) liquid parameters and solid species data are regressed from properties and solubility data at full temperature range. Together the activity coefficient model, property models and parameters of liquid and solid offer a comprehensive thermodynamic model system for the typical bittern of MgCl2-CaCl2-H2O binary and ternary systems, and it shows excellent agreement with the literature data for the ternary and binary systems. The successful prediction of complete phase diagram of ternary system shows that the model has the ability to deal with high concentration and high non-ideality system, and the ability to extrapolate the temperature.
    Biotechnology and Bioengineering
    Effect of ultrasonic assisted KOH pretreatment on physiochemical characteristic and anaerobic digestion performance of wheat straw
    Rashid Mustafa Korai, Xiujin Li
    2020, 28(9):  2409-2416.  doi:10.1016/j.cjche.2020.06.022
    Abstract ( 152 )   PDF (2460KB) ( 79 )  
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    In this study, ultrasonic field was applied during potassium hydroxide (KOH) pretreatment of wheat straw (WS). Three concentrations of KOH (2%, 4%, and 6%) were tested during pretreatment. The results showed that there was a significant influence of the ultrasonic assisted KOH pretreatment (KOHUpt) on physiochemical characteristics of WS during pretreatment as well as on digester performance. The pretreatment time was optimized to 36 h for all KOH concentrations. The highest total volatile fatty acid (TVFA) productions (3189 mg·L-1) from 6% KOHUpt samples were observed. Similarly, the SEM analysis and FTIR observation revealed that KOHUpt effectively disrupted the physical morphology of WS and successful breaking of lignin and hemicellulose linkage between carboxyl groups. Moreover, the highest biogasification (555 ml·(g VSloaded)-1) and biomethane productions (282 ml·(g VSloaded)-1) from 4%KOHUpt digesters, with 69% of biodegradability, indicated significant availability of organic matter from KOHUpt. The R2 values (0.993-0.998) in Modified Gompertz Model indicated that the model was feasible to predict methane yield for this study. Similarly, the Bo values for 4%KOHUpt (283.30 ± 2.74 ml·(gVSloaded)-1) were also in agreement to the experimental methane yield. These results suggested that ultrasonic addition during KOH pretreatment of WS can effectively increase the organic yield during pretreatment. Moreover, the increase in methane production from 4% KOHUpt suggested that digester performance can be improved with lower KOH concentrations using this pretreatment.
    Energy, Resources and Environmental Technology
    Petroleum coke conversion behavior in catalyst-assisted chemical looping combustion
    Xianyu Liu, Huijun Ge, Shiwei Ma, Shangyi Yin, Ping Lu, Laihong Shen, Hongcun Bai, Wei Wang, Tao Song
    2020, 28(9):  2417-2424.  doi:10.1016/j.cjche.2020.06.012
    Abstract ( 151 )   PDF (3123KB) ( 63 )  
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    Efficiently using petroleum coke as fuel and reducing carbon emission meanwhile have become attractive in oil processing industry. The paper is focused on the application of Chemical Looping Combustion (CLC) with petroleum coke, with the purpose of investigating its combustion performance and effects of potassium. Some experiments were performed in a laboratory scale fluidized bed facility with a natural manganese-based oxygen carrier. Experimental results indicated that the coke conversion is very sensitive to reaction temperature. The present natural manganese-based oxygen carrier decorated by K has little effect on the improvement of coke conversion. XRD, SEM-EDX, and H2-TPR were adopted to characterize the reacted oxygen carrier samples. After being decorated by K, the oxygen carrier's capacity of transferring oxygen was decreased. A calcination temperature above the melting point of K2CO3 (891 °C) shows better oxygen transfer reactivity in comparison to the one calcined at a lower temperature. The natural oxygen carrier used in the work has a high content of Si, which can easily react with K to form K(FeSi2O6). Further, irrespective of reaction temperature, the coke conversion can be significantly enhanced by decorating the coke with K, with a demonstration of remarkably shorter reaction time, faster average coke gasification rate and higher average carbon conversion rate.
    Sulfonated polybenzimidazole/amine functionalized titanium dioxide (sPBI/AFT) composite electrolyte membranes for high temperature proton exchange membrane fuel cells usage
    Muhammad A. Imran, Tiantian Li, Xuemei Wu, Xiaoming Yan, Abdul-Sammed Khan, Gaohong He
    2020, 28(9):  2425-2437.  doi:10.1016/j.cjche.2020.05.016
    Abstract ( 143 )   PDF (2854KB) ( 259 )  
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    The novel sulfonated polybenzimidazole (sPBI)/amine functionalized titanium dioxide (AFT) composite membrane is devised and studied for its capability of the application of high temperature proton exchange membrane fuel cells (HT-PEMFCs), unlike the prior low temperature AFT endeavors. The high temperature compatibility was actualized because of the filling of free volumes in the rigid aromatic matrix of the composite with AFT nanoparticles which inhibited segmental motions of the chains and improved its thermal stability. Besides, amine functionalization of TiO2 enhanced their dispersion character in the sPBI matrix and shortened the interparticle separation gap which finally improved the proton transfer after establishing interconnected pathways and breeding more phosphoric acid (PA) doping. In addition, the appeared assembled clusters of AFT flourished a superior mechanical stability. Thus, the optimized sPBI/AFT (10 wt%) showed 65.3 MPa tensile strength; 0.084 S·cm-1 proton conductivity (at 160 °C; in anhydrous conditions), 28.6% water uptake and PA doping level of 23 mol per sPBI repeat unit. The maximum power density peak for sPBI/AFT-10 met the figure of 0.42 W·cm-2 at 160 °C (in dry conditions) under atmospheric pressure with 1.5 and 2.5 stoichiometric flow rates of H2/air. These results affirmed the probable fitting of sPBI/AFT composite for HT-PEMFC applications.
    The numerical simulation of a new double swirl static mixer for gas reactants mixing
    Zhuokai Zhuang, Jingtian Yan, Chenglang Sun, Haiqiang Wang, Yuejun Wang, Zhongbiao Wu
    2020, 28(9):  2438-2446.  doi:10.1016/j.cjche.2020.05.008
    Abstract ( 147 )   PDF (5041KB) ( 98 )  
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    For the nitrogen oxide removal processes, high performance gas mixer is deeply needed for the injection of NH3 or O3. In this study, a new type of double swirl static mixer in gas mixing was investigated using computational fluid dynamics (CFD). The results obtained using Particle Image Velocimetry (PIV) correlated well with the results obtained from simulation. The comparisons in pressure loss between the experimental results and the simulation results showed that the model was suitable and accurate for the simulation of the static mixer. Optimal process conditions and design were investigated. When L/D equaled 4, coefficient of variation (COV) was <5%. The inlet velocity did not affect the distributions of turbulent kinetic energy. In terms of both COV and pressure loss, the inner connector is important in the design of the static mixer. The nozzle length should be set at 4 cm. Taking both COV and pressure loss into consideration, the optimal oblique degree is 45°. The averaged kinetic energy changed according to process conditions and design. The new static mixer resulted in improved mixing performance in a more compact design. The new static mixer is more energy efficient compared with other SV static mixers. Therefore, the double swirl static mixer is promising in gas mixing.
    A novel method for the management of sulfone-rich waste produced in the oxidative desulfurization (ODS) process
    Sobhan Farahani, Mohammad Amin Sobati
    2020, 28(9):  2447-2456.  doi:10.1016/j.cjche.2020.04.004
    Abstract ( 129 )   PDF (5840KB) ( 59 )  
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    The oxidative desulfurization (ODS) process is one of the new desulfurization processes for the production of clean fuels. Despite the benefits of the ODS process, this process faces several important challenges. One of the most important challenges of this process is the management of a waste which is rich of sulfone compounds. In the present study, a new strategy which is the addition of waste to the bitumen with other solid waste such as high density polyethylene (HDPE) waste has been investigated. The experimental design method was applied to investigate the effect of addition of the sulfone and HDPE wastes to the properties of the bitumen blends including degree of penetration, softening point, and mass loss. It was found that the sulfone waste can be added to the bitumen as a softener. The results showed that several grades of bitumen including 50/60, 60/70, 85/100 can be produced through the addition of sulfone waste along with the HDPE waste to the base 60/70 bitumen. In general, the application of simple processes such as mixing the wastes with the bitumen can reduce the cost of waste management, considerably.
    Simultaneous desulfurization and denitrification of flue gas by pre-ozonation combined with ammonia absorption
    Baowei Wang, Shumei Yao, Yeping Peng
    2020, 28(9):  2457-2466.  doi:10.1016/j.cjche.2020.05.001
    Abstract ( 116 )   PDF (931KB) ( 130 )  
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    A process of simultaneous desulfurization and denitrification of flue gas was conducted in this study. The flue gas containing 200 mg·m-3 NO, 1000-4000 mg·m-3 SO2, 3%-9% O2, and 10%-20% CO2 was first oxidized by O3 and then absorbed by ammonia in a bubbling reactor. Increasing the ammonia concentration or the SO2 content in flue gas can promote the absorption of NOX and extend the effective absorption time. On the contrary, both increasing the absorbent temperature or the O2 content shorten the effective absorption time of NOX. The change of solution pH had substantial influence on NOX absorption. In the presence of CO2, the NOX removal efficiency reached 89.2% when the absorbent temperature was raised to 60 °C, and the effective absorption time can be maintained for 8 h, which attribute to the buffering effect in the absorbent. Besides, both the addition of Na2S2O3 and urea can promote the NOX removal efficiency when the absorbent temperature is 25 °C, and the addition of Na2S2O3 had achieved better results. The advantage of adding Na2S2O3 became less evident at higher absorbent temperature and coexistence of CO2. In all experiments, SO2 removal efficiency was always above 99%, and it was basically not affected by the above factors.
    Adsorption of cationic dyes from aqueous solution using hydrophilic silica aerogel via ambient pressure drying
    Qun Liu, Yuan Liu, Zhihua Zhang, Xiaodong Wang, Jun Shen
    2020, 28(9):  2467-2473.  doi:10.1016/j.cjche.2020.04.023
    Abstract ( 166 )   PDF (1570KB) ( 84 )  
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    In order to remove the organic dyes of textile waste water, the silica aerogel was successfully prepared by using E-40 as a novel precursor and then dried in ambient pressure. The synthesized sample was verified by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). After calcining, the hydrophilic silica aerogel (HSA) was used as adsorbent to remove Methylene Blue (MB), Malachite Green (MG), and Gentian Violet (GV) from aqueous solution. The effects of initial concentration of dyes and adsorbent dosage on the adsorption process were examined. It was found that HSA showed excellent adsorption capacities, the maximum percentage of removal dyes could reach 98%. Herein, the Langmuir, Freundlich and de Boer-Zwikker isotherm modes were employed to discuss the adsorption behavior. The results indicated that the de Boer-Zwikker model can effectively describe the adsorption behavior. Besides, the HSA could be utilized as the recyclable adsorbent in degradation experiment, after five cycles, no obvious loss of adsorption capacity was found. As an efficient, low-cost, environmental friendly and recyclable adsorbent, silica aerogel is expected to be used for dyes removal.
    Materials and Product Engineering
    Improved flame resistance properties of unsaturated polyester resin with TiO2-MXOY solid superacid
    Xuexi Chen, Mei Wan, Ming Gao, Yanxia Wang, Deqi Yi
    2020, 28(9):  2474-2482.  doi:10.1016/j.cjche.2020.06.018
    Abstract ( 141 )   PDF (3300KB) ( 163 )  
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    Five SO42-/TiO2-MXOY solid super acids (SSA: Cu@Ti:SSA, Zr@Ti:SSA, Fe@Ti:SSA, Mn@Ti:SSA, Mo@Ti:SSA) were successfully prepared by sol-gel method, and its chemical structure and element content were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS). Then, a compound flame retardant system containing SSA and ammonium polyphosphate/montmorillonite (AM) were was introduced into an unsaturated polyester resin (UPR) to enhance the flame retardance. The effect of SSA on the flammability and thermal stability of the UPR was evaluated by the limiting oxygen index (LOI), cone calorimeter test (CCT) and thermogravimetric analysis (TGA). The LOI results showed that the flame retardance of the UPR composites was significantly improved with the addition of SSA. Moreover, their heat release rate (HRR), total heat release (THR), the smoke production rate (SPR) and CO and CO2 yield were much decreased. In addition, the initial decomposition temperature of UPR/AM/SSA was delayed, indicating that their thermal stability was increased, and the residual char of UPR/AM/SSA was also increased due to strong catalytic of SSA ability for esterification and dehydration. Furthermore, the microstructure of the residual char after combustion of the UPR composites was studied by the scanning electron microscopy (SEM), and it was found that the char layer structure was more continuous and dense after the addition of the SSA. In sum up, the synergistic effect between SSA and AM was the main factor for the great improvement of flame retardant of UPR composites.
    Influence of flocculant polyacrylamide on concentration of titanium white waste acid by direct contact membrane distillation
    Biao Hu, Jintao Ouyang, Lanying Jiang
    2020, 28(9):  2483-2496.  doi:10.1016/j.cjche.2020.03.022
    Abstract ( 137 )   PDF (6277KB) ( 104 )  
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    Effort has been made to investigate the concentration of titanium white waste acid (TWWA) by direct contact membrane distillation (DCMD) and the focus is the influence of polyacrylamide (PAM) on membrane wetting and fouling. It was found that the presence of PAM in feed reduced membrane flux and retarded wetting development, even though its level in feed of H2SO4 solution was only 0.0002 wt%. The difference between the tests using pure water and neat PAM aqueous solution, respectively, as feed also indicated the above effect registered with PAM. AFM results showed that the addition of PAM in feed solution changed the membrane shell surface morphology. However, conclusive proof of the PAM existence in membrane cross-section and inner surface was not obtained, probably due to its low concentration in feed solution. Two approaches were tried to recover membrane flux. In comparison with operation w/o any treatment, HCl solution rinsing did not lead to obvious improvement in membrane flux recovery, while rinsing combined with gas purge has clearly delayed the degradation in acid concentration factor. Nevertheless, even the latter could not ensure long term stability. High tortuosity and low hydrophobicity of the membranes used were suggested as underlying causes and should be addressed in the future.
    Process intensification for rare-earth doped luminescent nanomaterials
    Kai Liu, Hongjie Zhang
    2020, 28(9):  2497-2497.  doi:10.1016/j.cjche.2020.07.013
    Abstract ( 95 )   PDF (297KB) ( 123 )  
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