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ChemEngineering, Volume 2, Issue 4 (December 2018)

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Open AccessArticle Dry Reforming in a Milli-Scale Reactor Driven by Simulated Sunlight
ChemEngineering 2018, 2(4), 50; https://doi.org/10.3390/chemengineering2040050 (registering DOI)
Received: 31 August 2018 / Revised: 23 September 2018 / Accepted: 11 October 2018 / Published: 18 October 2018
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Abstract
In this study, a directly irradiated, milli-scale chemical reactor with a simple nickel catalyst was designed for dry reforming of methane for syngas. A milli-scale reactor was used to facilitate rapid heating, which is conducive to combating thermal transience caused by intermittent solar
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In this study, a directly irradiated, milli-scale chemical reactor with a simple nickel catalyst was designed for dry reforming of methane for syngas. A milli-scale reactor was used to facilitate rapid heating, which is conducive to combating thermal transience caused by intermittent solar energy, as well as reducing startup times. Milli-scale reactors also allow for a distributed and modular process to produce chemicals on a more local scale. In this setup, the catalyst involved in the reaction is located directly in the focal area of the solar simulator, resulting in rapid heating. The effects of mean residence time and temperature on conversion and energy efficiency were tested. The process, which is intended to store thermal energy as chemical enthalpy, achieved 10% thermal-to-chemical energy conversion efficiency at a mean residence time of 0.028 s, temperature of 1000 °C, and molar feed ratio of 1:1 CO2:CH4. A significant portion of the thermal energy input into the reactor was directed toward sensible heating of the feed gas. Thus, this technology has potential to achieve solar-to-chemical efficiency with the integration of recuperative heat exchange. Full article
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Open AccessArticle Modeling of Copper Adsorption on Mesoporous Carbon CMK-3: Response Surface Design
ChemEngineering 2018, 2(4), 49; https://doi.org/10.3390/chemengineering2040049
Received: 15 August 2018 / Revised: 2 October 2018 / Accepted: 11 October 2018 / Published: 14 October 2018
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Abstract
CMK-3 mesoporous carbon was nanocast from SBA-15 silica. The obtained carbon was characterized by nitrogen sorption isotherms, X-ray diffraction and transmission electron microscopy (TEM). The batch adsorption tests were done at constant pH taking into account the initial metal ion concentration, adsorbent mass
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CMK-3 mesoporous carbon was nanocast from SBA-15 silica. The obtained carbon was characterized by nitrogen sorption isotherms, X-ray diffraction and transmission electron microscopy (TEM). The batch adsorption tests were done at constant pH taking into account the initial metal ion concentration, adsorbent mass and temperature. A statistical study using a response surface design method was done to develop a mathematical model to predict copper adsorption on CMK-3 as a function of the mentioned experimental factors. It was found that all these parameters are significant, and copper concentration has the greatest effect on adsorption among them. Moreover, the obtained model proved to be adequate in predicting copper adsorption on CMK-3 and its performance under different experimental conditions. Full article
(This article belongs to the Special Issue Carbon-Based Materials and Their Electrochemical Applications)
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Open AccessArticle Dry Reforming of Methane in a Pd-Ag Membrane Reactor: Thermodynamic and Experimental Analysis
ChemEngineering 2018, 2(4), 48; https://doi.org/10.3390/chemengineering2040048
Received: 13 September 2018 / Revised: 2 October 2018 / Accepted: 9 October 2018 / Published: 10 October 2018
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Abstract
The present work is a study of CO2 Reforming of Methane (DRM) carried out in a catalytic Pd-based membrane reactor. A detailed thermodynamic analysis is carried out, calculating the chemical equilibrium parameters in two different cases: (a) DRM along with the Reverse
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The present work is a study of CO2 Reforming of Methane (DRM) carried out in a catalytic Pd-based membrane reactor. A detailed thermodynamic analysis is carried out, calculating the chemical equilibrium parameters in two different cases: (a) DRM along with the Reverse Water Gas Shift (RWGS) reaction and (b) DRM along with both RWGS and the Boudouard Reaction (BR). The performance of membrane reactor is then experimentally analyzed in terms of methane conversion, hydrogen recovery and H2/CO reaction selectivity by varying feed pressure and CO2/CH4 feed molar ratio and 500 °C and GHSV = 100 h−1. Among the obtained results, a CH4 conversion of about 26% and a H2 recovery of 47% are achieved at low feed pressures, exceeding the traditional reactor equilibrium conversion. This effect can be attributed to the favorable thermodynamics coupled to the hydrogen permeation through the membrane. This study further demonstrates the general effectiveness of membrane-integrated reaction processes, which makes the production of syngas more efficient and performing, providing important environmental benefits. Full article
(This article belongs to the Special Issue Membrane and Membrane Reactors Operations in Chemical Engineering)
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Open AccessArticle Effective Concentration of Ionic Liquids for Enhanced Saccharification of Cellulose
ChemEngineering 2018, 2(4), 47; https://doi.org/10.3390/chemengineering2040047
Received: 20 July 2018 / Revised: 22 August 2018 / Accepted: 27 September 2018 / Published: 3 October 2018
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Abstract
In an aqueous enzymatic saccharification using cellulase, the dissolution of crystalline cellulose is one of the rate-limiting steps. Insoluble cellulose powder was preliminarily heat-treated with ionic liquids (ILs), such as [Bmim][Cl] (1-butyl-3-methylimidazolium chloride) and [Amim][Cl] (1-allyl-3-methylimidazolium chloride), which enable the production of soluble
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In an aqueous enzymatic saccharification using cellulase, the dissolution of crystalline cellulose is one of the rate-limiting steps. Insoluble cellulose powder was preliminarily heat-treated with ionic liquids (ILs), such as [Bmim][Cl] (1-butyl-3-methylimidazolium chloride) and [Amim][Cl] (1-allyl-3-methylimidazolium chloride), which enable the production of soluble cellulose. On the other hand, the presence of ILs leads to a denaturation of enzymes. Using cellulase from Trichoderma viride, the effects of [Bmim][Cl] and [Amim][Cl] in the enzymatic saccharification were compared. The production of glucose was optimized with 5 wt%-ILs, both for [Bmim][Cl] and for [Amim][Cl]. The significant inhibiting effects of ILs (IL concentration >10 wt%) could be due to the denaturation of cellulase, because the peak shifts of intrinsic tryptophan fluorescence were observed in the presence of 7.5 wt%-ILs. To analyze kinetic parameters, the Langmuir adsorption model and the Michaelis-Menten model were employed. The investigation suggests that [Amim][Cl] can provide soluble cellulose more efficiently, and can promote enzymatic saccharification in the IL concentration below 5 wt%. Full article
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Open AccessArticle Empirical Kinetic Modelling of the Effect of l-Ascorbic Acid on the Cu(II)-Induced Oxidation of Quercetin
ChemEngineering 2018, 2(4), 46; https://doi.org/10.3390/chemengineering2040046
Received: 2 July 2018 / Revised: 20 August 2018 / Accepted: 29 September 2018 / Published: 1 October 2018
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Abstract
This study aimed at investigating the effect of l-ascorbic acid on the Cu2+-induced oxidation of quercetin, within a pH range from 6.7 to 8.3 and temperatures varying from 53 to 87 °C. Initial examinations showed that quercetin degradation obeyed apparent
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This study aimed at investigating the effect of l-ascorbic acid on the Cu2+-induced oxidation of quercetin, within a pH range from 6.7 to 8.3 and temperatures varying from 53 to 87 °C. Initial examinations showed that quercetin degradation obeyed apparent first-order kinetics and it was significantly affected by temperature. Modelling of the effect of l-ascorbic acid by implementing response surface methodology suggested that l-ascorbic acid did not impact quercetin oxidation significantly (p < 0.05) and led to an empirical kinetic model based on temperature (T) and pH. Liquid chromatography–diode array–mass spectrometry analyses revealed the presence of typical quercetin degradation and oxidation products, including protocatechuic acid and 2-(hydroxybenzoyl)-2-hydroxybenzofuran-3(2H)-one. It was concluded that the formation of l-ascorbyl or other radicals (superoxide anion) may be involved in quercetin oxidation and this fact merits further attention to illuminate the possible beneficial or adverse nutritional consequences of such reactions in foods. Full article
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Open AccessArticle UV-Vis Spectroscopy and Chemometrics for the Monitoring of Organosolv Pretreatments
ChemEngineering 2018, 2(4), 45; https://doi.org/10.3390/chemengineering2040045
Received: 15 August 2018 / Revised: 2 September 2018 / Accepted: 10 September 2018 / Published: 21 September 2018
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Abstract
Lignocellulosic agricultural side products like wheat straw are widely seen as an important contribution to a sustainable future economy. However, the optimization of biorefinery processes, especially the pretreatment step, is crucial for an economically viable biorefinery. The monitoring of this pretreatment process in
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Lignocellulosic agricultural side products like wheat straw are widely seen as an important contribution to a sustainable future economy. However, the optimization of biorefinery processes, especially the pretreatment step, is crucial for an economically viable biorefinery. The monitoring of this pretreatment process in terms of delignification and the generation of the fermentation inhibitors acetic acid, furfural, and hydroxymethylfurfural (HMF) is essential in order to adapt the process parameters for a desired outcome and an economical operation. However, traditional wet chemistry methods are time-consuming and not suitable for on-line process monitoring. Therefore, UV-Vis spectroscopy in combination with partial least-squares regression was used for the determination of the concentrations of lignin, acetic acid, furfural, and HMF. Five different data blocks with increasing amounts of impurities were investigated to evaluate the influence of the inevitable impurities on the calibration models. Lignin showed a good prediction accuracy with 95% tolerance intervals between ±0.46 to ±1.6 mg/L for concentrations up to 30 mg/L. Also, the other components could be predicted with a sufficient accuracy for on-line process monitoring. A satisfactory calibration can be obtained with 10 to 20 reference samples valid at process temperatures between 160 °C and 180 °C. Full article
(This article belongs to the Special Issue Advances in Bio-Fuels Production)
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