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1.
Jian‐Ping Wen Chang‐Lin Wang Yan‐Xin Liu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(4):403-406
A new process for D ‐glucose hydrogenation in 50 wt% aqueous solution, into sorbitol in a 1.5 m3 gas–liquid–solid three‐phase flow airlift loop reactor (ALR) over Raney Nickel catalysts has been developed. Five main factors affecting the reaction time and molar yield to sorbitol, including reaction temperature (TR), reaction pressure (PR), pH, hydrogen gas flowrate (Qg) and content of active hydrogen, were investigated and optimized. The average reaction time and molar yield were 70 min and 98.6% under the optimum operating conditions, respectively. The efficiencies of preparation of sorbitol between the gas–liquid–solid three‐phase flow ALR and stirred tank reactor (STR) under the same operating conditions were compared. Copyright © 2004 Society of Chemical Industry 相似文献
2.
Wen Jianping Yuan Qing Pan Lei Mao Guozhu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(7):767-771
Aerobic treatment of refinery wastewater was carried out in a 200 dm3 gas–liquid–solid three‐phase flow airlift loop bioreactor, in which a biological membrane replaced the activated sludge. The influences of temperature, pH, gas–liquid ratio and hydraulic residence time on the reductions in chemical oxygen demand (COD) and NH4‐N were investigated and discussed. The optimum operation conditions were obtained as temperature of 25–35 °C, pH value of 7.0–8.0, gas–liquid ratio of 50 and hydraulic residence time of 4 h. The radial and axial positions had little influence on the local profiles of COD and NH4‐N. Under the optimum operating conditions, the effluent COD and NH4‐N were less than 100 mg dm?3 and 15 mg dm?3 respectively for more than 40 days, satisfying the national primary discharge standard of China (GB 8978‐1996). Copyright © 2005 Society of Chemical Industry 相似文献
3.
Tuan‐Huy Nguyen Adesoji A Adesina Ernest MT Yue Yong‐Joon Lee Andrei Khodakov Michael P Brungs 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(3):286-290
Thermogravimetric analysis (TGA) has been used to investigate the carburization kinetics of Mo–W sulfide using an H2:C3H8 feed mixture. The effect of heating rate over the range 1–10 K min?1 showed that up to four different carburized products may be formed but the critical (peak) temperature for formation of these species and the amount (peak height) of each species formed are highly dependent on the heating rate employed. The critical temperature increased linearly with heating rate for each of the four products. The four TGA peaks corresponding to the four phase transformation species are consistent with XRD identifiable species, namely; α‐Mo2C, β‐Mo2C, W and MoC1?x. Isothermal conversion–time data at three different temperatures are described by a reaction‐controlled shrinking core model implicating a first‐order dependency on the H2:C3H8 ratio. The reaction exhibited fractional order dependence on the metal sulfide concentration, the associated global activation energy estimated as 227 kJ mol?1 is representative of a non‐catalytic gas–solid reaction. Copyright © 2004 Society of Chemical Industry 相似文献
4.
A Victoria Nawaby Y Paul Handa Xia Liao Yamamoto Yoshitaka Mizumoto Tomohiro 《Polymer International》2007,56(1):67-73
The sorption of compressed gases in polymers causing a reduction in the glass transition temperature (Tg) is well established. There is, however, limited information on polymer–gas systems with favorable interactions, producing a unique retrograde behavior. This paper reports on using a combination of established techniques of in situ gravimetric and stepwise heat capacity (Cp) measurements using high‐pressure differential scanning calorimetry (DSC) to demonstrate the occurrence of this behavior in acrylonitrile–butadiene–styrene copolymer (ABS)–CO2 and syndiotactic poly(methyl methacrylate) (sPMMA)–CO2 systems. The solubility and diffusion coefficient of CO2 in the range 0 to 65 °C and pressures up to 5.5 MPa were determined, which resulted in a heat of sorption of ? 15.5 and ? 15 kJ mol?1, and an activation energy for diffusion of 28.3 and 32.1 kJ mol?1 in the two systems, respectively. The fundamental kinetic data and the changes in Cp of the polymer–gas systems were used to determine the plasticization glass transition temperature profile, its relationship to the amount of gas dissolved in the polymer, and hence the formation of nano‐morphologies. Copyright © 2006 Society of Chemical Industry 相似文献
5.
Wen Jianping Chen Yu Jia Xiaoqiang Mao Guozhu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(1):17-22
Toluene, a kind of volatile organic compound (VOC), is widely used as a solvent (paints and coatings, gums, resins, rubber) as well as a reagent (medicines, dyes, perfumes) and is one of the components of gasoline. Over the more recent decades, many studies have led to the development of biological methods to treat toluene. This paper presents the results of a study on the treatment of airborne toluene using a laboratory‐scale gas–liquid–solid three‐phase airlift loop bioreactor containing immobilized cells. Based on the optimum operating conditions such as the temperature of 28–30 °C, pH of 7.0–7.2, and an empty bed residence time (EBRT) of 39.6 s, a continuous bioprocess showed that this immobilized airlift loop bioreactor had a steady‐state performance within 15 days, the outlet concentrations of toluene were lower than the national emission standard in China (GB 16297‐1996), and the chemical oxygen demand and NH4+‐N of the effluent also satisfied the primary discharge standard in China (GB 8978‐1996). In addition, this immobilized airlift loop bioreactor had a good ability to tolerate shock loads, while the maximum elimination capacity of toluene was 168 g m?3 h?1 which was higher than those not only in biofilters and biotrickling filters but also in the airlift bioreactor with free microorganisms. Copyright © 2005 Society of Chemical Industry 相似文献
6.
Intensification of convective heat transfer in a stator–rotor–stator spinning disc reactor
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Michiel M. de Beer Jos T.F. Keurentjes Jaap C. Schouten John van der Schaaf 《American Institute of Chemical Engineers》2015,61(7):2307-2318
A stator–rotor–stator spinning disc reactor is presented, which aims at intensification of convective heat‐transfer rates for chemical conversion processes. Single phase fluid‐rotor heat‐transfer coefficients hr are presented for rotor angular velocities rad s?1 and volumetric throughflow rates m3s?1. The values of hr are independent of and increase from 0.95 kWm?2K?1 at ω = 0 rad s?1 to 34 kWm?2K?1 at ω = 157 rad s?1. This is a factor 2–3 higher than values achievable in passively enhanced reactor‐heat exchangers, due to the 1–2 orders of magnitude larger specific energy input achievable in the stator–rotor–stator spinning disc reactor. Moreover, as hr is independent of , the heat‐transfer rates are independent of residence time. Together with the high mass‐transfer rates reported for rotor–stator spinning disc reactors, this makes the stator–rotor–stator spinning disc reactor a promising tool to intensify heat‐transfer rates for highly exothermal chemical reactions. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2307–2318, 2015 相似文献
7.
Combined experimental and computational investigation of thermodynamics and phase equilibria in the CaO–TiO2 system
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Weiping Gong Lili Wu Alexandra Navrotsky 《Journal of the American Ceramic Society》2018,101(3):1361-1370
Phase relations in the CaO–TiO2 system are of considerable interest in geology, metallurgy, and ceramics. Despite a number of studies of phase equilibria in the CaO–TiO2 system, there are still some open questions regarding the stability of intermediate compounds. In this work, a series of specimens with different CaO:TiO2 ratios were prepared by solid‐state reaction. The heat capacities of Ca3Ti2O7 and Ca4Ti3O10 from 300 to 1073 K were measured by differential scanning calorimetry and their formation enthalpies from the component oxides at 298 K were measured by high temperature oxide melt solution calorimetry. Using phase diagram information and thermodynamic data from the literature and the present measurements, thermodynamic optimization of the CaO–TiO2 system was carried out by the CALPHAD technique. The phase diagram and the thermodynamic properties of the CaO–TiO2 system were calculated using the obtained thermodynamic database, which clarify the stable and metastable phase equilibria of the system. The thermodynamic stability of the various compounds was discussed. 相似文献
8.
Arie Jan van Houwelingen Willie Nicol 《American Institute of Chemical Engineers》2011,57(5):1310-1319
A novel method for the measurement of wetting efficiency in a trickle‐bed reactor under reaction conditions is introduced. The method exploits reaction rate differences of two first‐order liquid‐limited reactions occurring in parallel, to infer wetting efficiencies without any other knowledge of the reaction kinetics or external mass transfer characteristics. Using the hydrogenation of linear‐ and isooctenes, wetting efficiency is measured in a 50‐mm internal diameter, high‐pressure trickle‐bed reactor. Liquid–solid mass transfer coefficients are also estimated from the experimental conversion data. Measurements were performed for upflow operation and two literature‐defined boundaries of hydrodynamic multiplicity in trickle flow. Hydrodynamic multiplicity in trickle flow gave rise to as much as 10% variation in wetting efficiency, and 10–20% variation in the specific liquid–solid mass transfer coefficient. Conversions for upflow operation were significantly higher in trickle‐flow operation, because of complete wetting and better liquid–solid mass transfer characteristics. © 2010 American Institute of Chemical Engineers AIChE J, 2011. 相似文献
9.
Frans Visscher Jos de Hullu Mart H. J. M. de Croon John van der Schaaf Jaap C. Schouten 《American Institute of Chemical Engineers》2013,59(7):2686-2693
A reactor model for the single‐phase rotor–stator spinning disk reactor based on residence time distribution measurements is described. For the experimental validation of the model, the axial clearance between the rotor and both stators is varied from 1.0 × 10?3 to 3.0 × 10?3 m, the rotational disk speed is varied from 50 to 2000 RPM, and the volumetric flow rate is varied from 7.5 × 10?6 to 22.5 × 10?6 m3 s?1. Tracer injection experiments show that the residence time distribution can be described by a plug flow model in combination with 2–3 ideally stirred tanks‐in‐series. The resulting reactor model is explained with the effect of turbulence, the formation of Von Kármán and Bödewadt boundary layers, and the effect of the volumetric flow rate. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2686–2693, 2013 相似文献
10.
Several glasses synthesized by sol–gel route and based on the BaO–B2O3–X–Al2O3–SiO2 (X = CaO, MgO) glass system have been investigated to evaluate their applicability as sealant for solid oxide fuel cell (SOFC). Chemical interactions with K41X stainless steel and hydrogen‐tightness of these materials were evaluated after operations at high temperatures over 1,000 h in air atmosphere. Formation of a new phase at the steel–glass interface and formation of porosity in the glass were observed and determined as critical problems over mid‐term operations. The role of MgO is important to obtain a gas‐tight sealing. Application of the glass paste without binder addition was performed in order to avoid possible residual porosity related problems. The best glass was finally used as sealant between anodic and cathodic compartments in complete SOFCs operated at 760 and at 800 °C. Open circuit voltages and power densities of the cells were recorded during the first hours of operation. 相似文献
11.
Ji‐Zhao Liang 《应用聚合物科学杂志》2002,85(3):606-611
The influence of temperatures and flow rates on the rheological behavior during extrusion of acrylonitrile–butadiene–styrene (ABS) terpolymer melt was investigated by using a Rosand capillary rheometer. It was found that the wall shear stress (τw) increased nonlinearly with increasing apparent shear rates and the slope of the curves changed suddenly at a shear rate of about 103 s?1, whereas the melt‐shear viscosity decreased quickly at a τw of about 200 kPa. When the temperature was fixed, the entry‐pressure drop and extensional stress increased nonlinearly with increasing τw, whereas it decreased with a rise of temperature at a constant level of τw. The relationship between the melt‐shear viscosity and temperature was consistent with an Arrhenius expression. The results showed that the effects of extrusion operation conditions on the rheological behavior of the ABS resin melt were significant and were attributable to the change of morphology of the rubber phase over a wide range of shear rates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 606–611, 2002 相似文献
12.
A novel method has been developed to modify the natural polymer chitosan. The process utilizes a monomer prepared by employing a Morita–Baylis–Hillman (MBH) reaction. Specifically, the vinyl monomer 2‐[hydroxy(pyridin‐3‐yl)methyl]acrylonitrile (HPA) was synthesized using a high‐yielding MBH reaction of acrylonitrile with pyridine‐3‐carboxaldehyde in the presence of 1,4‐diazabicyclo[2.2.2]octane. Conversion of HPA to 2‐cyano‐1‐(pyridin‐3‐yl)allyl acrylate (CPA) was then carried out by reaction of acryloyl chloride. The highly functionalized monomer CPA was grafted onto chitosan through a reaction in 2% acetic acid containing a persulfate and a sulfite (K2S2O8/Na2SO3) as redox promoter. An optimal grafting percentage of 123% is obtained when the grafting process is conducted at 60 °C for 4 h employing a 1:0.5 ratio of K2S2O8 and Na2SO3 at a concentration of 2.5 × 10?3 mol L?1. Chitosan‐graft‐poly[2‐cyano‐1‐(pyridin‐3‐yl)allyl acrylate] graft copolymers, having various grafting percentages, were characterized using Fourier transform infrared, 1H NMR and 13C NMR spectroscopies, X‐ray diffraction, thermogravimetric analysis and scanning electron microscopy. Finally, the results of studies probing the antimicrobial activities of the polymers against selected microorganisms show that the graft copolymers display higher growth inhibition activities against bacteria and fungi than does chitosan. © 2014 Society of Chemical Industry 相似文献
13.
Vasant R. Choudhary Vilas H. Rane 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1997,69(1):63-69
CaO–La2O3–MgO and BaO–La2O3–MgO catalysts with different compositions have been studied for their bulk and surface properties (viz. crystal phases, surface area, acidity/acid strength distribution, basicity/base strength distribution, etc.) and catalytic activity/selectivity in the oxidative coupling of methane (OCM) at different processing conditions (reaction temperature, 700–850°C; CH4/O2 ratio in feed, 3·0, 4·0 and 8·0 and GHSV, 102000 and 204000 cm3 g−1 h−1). The surface acidity and strong basicity of La2O3–MgO are found to be increased due to the addition of a third component (CaO or BaO), depending upon its concentration in the catalyst. The addition of CaO or BaO to La2O3–MgO OCM catalyst causes a significant improvement in its performance. Both the CaO- and BaO-containing catalysts show a high activity and selectivity at 800°C, whereas, the activity and selectivity of BaO-containing catalysts at 700°C is lower than that of CaO-containing catalysts. © 1997 SCI. 相似文献
14.
This article describes the reactive kinetics of nano‐CaO with CO2 in a sorption complex catalyst. Based on an observation of nano‐CaO reaction with CO2 has a fast surface reaction regime and followed by a slow diffusion‐controlled regime, a criterion has been proposed to divide the fast surface reaction regime and the slow diffusion‐controlled reaction regime. The kinetics of the fast surface reaction was studied, and a new ion reaction mechanism was proposed. A surface reaction‐controlled kinetic model with a Boltzmann equation, X = Xu?Xu/[1+exp((t?t0)k/Xu)], was developed. Experiments using nano‐CaO to react with CO2 in a fast surface reaction regime within a sorption complex catalyst were performed using thermogravimetric analysis at 773–873 K under a N2 atmosphere with 0.010–0.020 MPa CO2. The activation energy of the kinetic model for carbonation is 30.2 kJ/mol, and the average relative deviation of the sorption ratio is less than 9.8%. © 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献
15.
Haocui Zhang Guangwen Chen Jun Yue Quan Yuan 《American Institute of Chemical Engineers》2009,55(5):1110-1120
In this article, flow pattern of liquid film and flooding phenomena of a falling film microreactor (FFMR) were investigated using high‐speed CCD camera. Three flow regimes were identified as “corner rivulet flow,” “falling film flow with dry patches,” and “complete falling film flow” when liquid flow rate increased gradually. Besides liquid film flow in microchannels, a flooding presented as the flow of liquid along the side wall of gas chamber in FFMR was found at high liquid flow rate. Moreover, the flooding could be initiated at lower flow rate with the reduction of the depth of the gas chamber. CO2 absorption was then investigated under the complete falling flow regime in FFMR, where the effects of liquid viscosity and surface tension on mass transfer were demonstrated. The experimental results indicate that kL is in the range of 5.83 to 13.4 × 10?5 m s?1 and an empirical correlation was proposed to predict kL in FFMR. © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献
16.
Marius G. Gelhausen Shaoquan Yang Maximilian Cegla David W. Agar 《American Institute of Chemical Engineers》2017,63(1):208-215
This study introduces a novel reactor concept, referred to as the Siphon Reactor, for intensified phase contacting of gas–liquid reactants on heterogeneous catalysts. The reactor comprises a fixed catalyst bed in a siphoned reservoir, which is periodically filled and emptied. This serves to alternate liquid–solid and then gas–liquid mass transfer processes. As the duration of each phase can be manipulated, mass transfer can be deliberately harmonized with the reaction. Residence time experiments demonstrate that, in contrast to periodically operated trickle‐bed reactors, the static liquid hold‐up is exchanged frequently and uniformly due to the complete homogeneous liquid wetting. A mathematical model describing the siphon hydrodynamics was developed and experimentally validated. The model was extended to account for a heterogeneously catalyzed gas–liquid reaction and capture the influence of siphon operation on conversion and selectivity of a consecutive reaction. © 2016 American Institute of Chemical Engineers AIChE J, 63: 208–215, 2017 相似文献
17.
N‐Phenylmaleimide–N‐(p‐hydroxy)phenylmaleimide–styrene terpolymer (HPMS), carrying reactive p‐hydroxyphenyl groups, was prepared and used to improve the toughness of cyanate ester resins. Hybrid modifiers composed of N‐phenylmaleimide–styrene copolymer (PMS) and HPMS were also examined for further improvement in toughness. Balanced properties of the modified resins were obtained by using the hybrid modifiers. The morphology of the modified resins depends on HPMS structure, molecular weight and content, and hybrid modifier compositions. The most effective modification of the cyanate ester resin was attained because of the co‐continuous phase structure of the modified resin. Inclusion of the modifier composed of 10 wt% PMS (Mw 136 000 g mol?1) and 2.5 wt% HPMS (hydroxyphenyl unit 3 mol%, Mw 15 500 g mol?1) led to 135% increase in the fracture toughness (KIC) for the modified resin with a slight loss of flexural strength and retention of flexural modulus and glass transition temperature, compared with the values for the unmodified resin. Furthermore, the effect of the curing conditions on the mechanical and thermal properties of the modified resins was examined. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified cyanate ester resin system. © 2001 Society of Chemical Industry 相似文献
18.
Jian‐Feng Chen Gui‐Zi Chen Jie‐Xin Wang Lei Shao Peng‐Fei Li 《American Institute of Chemical Engineers》2011,57(1):239-249
High‐throughput microporous tube‐in‐tube microchannel reactor (MTMCR) was first designed and developed as a novel gas–liquid contactor. Experimentally measured kLα in MTMCR is at least one or two orders of magnitude higher than those in the conventional gas–liquid contactors. A high throughput of 500 L/h for gas and 43.31 L/h for liquid is over 60 times higher than that of T‐type microchannel. An increase of the gas or liquid flow rate, as well as a reduction of the micropore size and annular channel width of MTMCR, could greatly intensify the gas–liquid mass transfer. The interfacial area, α, in MTMCR was measured to be as high as 2.2 × 105 m2/m3, which is much higher than those of microchannels (3400–9000 m2/m3) and traditional contactors (50–2050 m2/m3). The artificial neural network model was proposed for predicting α, revealing only an average absolute relative error of <5%. © 2010 American Institute of Chemical Engineers AIChE J, 2011 相似文献
19.
The subsolidus phase relationship in the CaO–CuO–TiO2 ternary system at 950°C in air was investigated. Total 26 samples having various nominal compositions were prepared by the solid‐state reaction at 950°C in air, and their equilibrium phases were analyzed by powder X‐ray diffraction (XRD). The CaCu3Ti4O12 phase exhibits variable stoichiometry and forms as the Ca1?xCu3+xTi4O12‐type (?0.019 ≤x ≤0.048) solid solution at 950°C in air. On the basis of our results and previous reports on the binary phase diagrams, the subsolidus phase diagram of the CaO–CuO–TiO2 ternary system could be constructed at 950°C in air. 相似文献
20.
Michiel M. de Beer Jos T. F. Keurentjes Jaap C. Schouten John van der Schaaf 《American Institute of Chemical Engineers》2016,62(10):3784-3796
Centrifugal intensification of condensation heat transfer in the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, volumetric throughflow rate , and average temperature driving force . For the current range of ω, heat transfer from the vapor bubbles to the condensate liquid is limiting, due to a relatively low gas–liquid interfacial area aGL. For rad s?1, a strong increase of aGL, results in increasing the reactor‐average condensation heat transfer coefficient hc from 1600 to 5600 W m?2 K?1, for condensation of pure dichloromethane vapor. Condensation heat transfer in the srs‐SDR is enhanced by rotation, independent of the vapor velocity. The intensified condensation comes at the cost of relatively high energy dissipation rates, indicating condensation in the srs‐SDR is more suited as a means to supply heat (e.g. in an intensified reactor‐heat exchanger), rather than for bulk cooling purposes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3784–3796, 2016 相似文献