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ChemEngineering
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ChemEngineering, Volume 3, Issue 3 (September 2019) – 17 articles

Cover Story (view full-size image): Separation is the most energetically demanding step in a carbon capture and utilization process. Catalysts able to selectively fix carbon dioxide from unpurified CO2-rich mixtures would thus allow the cost of such a process to be decreased significantly. CO2 is an important byproduct in epoxide synthesis, accounting for 0.02% of worldwide greenhouse emissions. As a proof of concept, we report on the first metal–organic framework able to catalyze the cycloaddition of CO2 to ethylene and propylene oxides in the absence of a solvent or cocatalyst. View this paper.
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29 pages, 1811 KiB  
Review
Desulphurisation of Biogas: A Systematic Qualitative and Economic-Based Quantitative Review of Alternative Strategies
by Oseweuba Valentine Okoro and Zhifa Sun
ChemEngineering 2019, 3(3), 76; https://doi.org/10.3390/chemengineering3030076 - 02 Sep 2019
Cited by 62 | Viewed by 13867
Abstract
The desulphurisation of biogas for hydrogen sulphide (H2S) removal constitutes a significant challenge in the area of biogas research. This is because the retention of H2S in biogas presents negative consequences on human health and equipment durability. The negative [...] Read more.
The desulphurisation of biogas for hydrogen sulphide (H2S) removal constitutes a significant challenge in the area of biogas research. This is because the retention of H2S in biogas presents negative consequences on human health and equipment durability. The negative impacts are reflective of the potentially fatal and corrosive consequences reported when biogas containing H2S is inhaled and employed as a boiler biofuel, respectively. Recognising the importance of producing H2S-free biogas, this paper explores the current state of research in the area of desulphurisation of biogas. In the present paper, physical–chemical, biological, in-situ, and post-biogas desulphurisation strategies were extensively reviewed as the basis for providing a qualitative comparison of the strategies. Additionally, a review of the costing data combined with an analysis of the inherent data uncertainties due underlying estimation assumptions have also been undertaken to provide a basis for quantitative comparison of the desulphurisation strategies. It is anticipated that the combination of the qualitative and quantitative comparison approaches employed in assessing the desulphurisation strategies reviewed in the present paper will aid in future decisions involving the selection of the preferred biogas desulphurisation strategy to satisfy specific economic and performance-related targets. Full article
(This article belongs to the Special Issue Advances in Biogas Desulfurization)
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15 pages, 5327 KiB  
Article
Using the Cahn–Hilliard Theory in Metastable Binary Solutions
by Viet-Nhien Tran Duc and Philip K. Chan
ChemEngineering 2019, 3(3), 75; https://doi.org/10.3390/chemengineering3030075 - 01 Sep 2019
Cited by 9 | Viewed by 4149
Abstract
A solution may be in one of three states: stable, unstable, or metastable. If the solution is unstable, phase separation is spontaneous and proceeds by spinodal decomposition. If the solution is metastable, the solution must overcome an activation barrier for phase separation to [...] Read more.
A solution may be in one of three states: stable, unstable, or metastable. If the solution is unstable, phase separation is spontaneous and proceeds by spinodal decomposition. If the solution is metastable, the solution must overcome an activation barrier for phase separation to proceed spontaneously. This mechanism is called nucleation and growth. Manipulating morphology using phase separation has been of great research interest because of its practical use to fabricate functional materials. The Cahn–Hilliard theory, incorporating Flory–Huggins free energy, has been used widely and successfully to model phase separation by spinodal decomposition in the unstable region. This model is used in this paper to mathematically model and numerically simulate the phase separation by nucleation and growth in the metastable state for a binary solution. Our numerical results indicate that Cahn–Hilliard theory is able to predict phase separation in the metastable region but in a region near the spinodal line. Full article
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10 pages, 3070 KiB  
Article
Preconcentration of Pb with Aminosilanized Fe3O4 Nanopowders in Environmental Water Followed by Electrothermal Atomic Absorption Spectrometric Determination
by Tomoharu Kusutaki, Mai Furukawa, Ikki Tateishi, Hideyuki Katsumata and Satoshi Kaneco
ChemEngineering 2019, 3(3), 74; https://doi.org/10.3390/chemengineering3030074 - 16 Aug 2019
Cited by 5 | Viewed by 2772
Abstract
A new preconcentration method to determine lead in environmental waters using the aminosilanized magnetite Fe3O4 powder sorbent has been developed. The preconcentration method was combined with electrothermal atomization atomic absorption spectrometry (ETAAS) and a graphite atomizer. Trace amount of sorbent [...] Read more.
A new preconcentration method to determine lead in environmental waters using the aminosilanized magnetite Fe3O4 powder sorbent has been developed. The preconcentration method was combined with electrothermal atomization atomic absorption spectrometry (ETAAS) and a graphite atomizer. Trace amount of sorbent (3 mg) could be applied into the preconcentration of Pb. According the preconcentration, the detection limits were 14 and 19 pg·mL−1 with bare and aminosilanized Fe3O4, respectively. The effect of interferent elements such as Al, Ca, Co, Fe, K, Mg, Na, Ni, and Zn (1000 ng·mL−1 versus Pb 1 ng·mL−1) on the preconcentration of Pb using bare magnetite was evaluated, and some elements (Al, Ni, and Zn) were found to interfere with the Pb preconcentration. The aminosilanized Fe3O4 sorbent was found to be effective in eliminating the severe interferences. The enrichment factors were 34 for the preconcentration with aminosilanized Fe3O4. The recovery of spiked Pb in the case of the sorbent with aminosilanized Fe3O4 was in the range of 75 to 110%. From the analytical data, the preconcentration technique was found to be useful for the determination of trace lead in environmental waters. Full article
(This article belongs to the Special Issue Advanced Functional Low-dimensional Materials and Their Applications)
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9 pages, 1865 KiB  
Article
Fracture Strength Evaluation of Agglomerates of Fatty Acid-Coated CaCO3 Nanoparticles by Nano-Indentation
by Yuki Kezuka and Masahiko Tajika
ChemEngineering 2019, 3(3), 73; https://doi.org/10.3390/chemengineering3030073 - 09 Aug 2019
Viewed by 3837
Abstract
Nanoparticles often form agglomerates during their manufacturing process. When nanoparticles form agglomerates, their inherent properties cannot be fully exploited. In this study, we attempted to establish a conventional method to evaluate the fracture strength of agglomerates into smaller parts. We used a commercially [...] Read more.
Nanoparticles often form agglomerates during their manufacturing process. When nanoparticles form agglomerates, their inherent properties cannot be fully exploited. In this study, we attempted to establish a conventional method to evaluate the fracture strength of agglomerates into smaller parts. We used a commercially available nano-indentation instrument with a flat indenter tip. We chose calcium carbonate nanoparticles with stearic acid coatings as model materials. It was found that the more fatty acid that is coated on the particle surface, the stronger the agglomerates become. The technique we propose in this study can be used to rapidly evaluate the fracture strength of nanoparticle agglomerates. Full article
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26 pages, 1415 KiB  
Review
Microbial Ecology of Biofiltration Units Used for the Desulfurization of Biogas
by Sylvie Le Borgne and Guillermo Baquerizo
ChemEngineering 2019, 3(3), 72; https://doi.org/10.3390/chemengineering3030072 - 07 Aug 2019
Cited by 27 | Viewed by 6514
Abstract
Bacterial communities’ composition, activity and robustness determines the effectiveness of biofiltration units for the desulfurization of biogas. It is therefore important to get a better understanding of the bacterial communities that coexist in biofiltration units under different operational conditions for the removal of [...] Read more.
Bacterial communities’ composition, activity and robustness determines the effectiveness of biofiltration units for the desulfurization of biogas. It is therefore important to get a better understanding of the bacterial communities that coexist in biofiltration units under different operational conditions for the removal of H2S, the main reduced sulfur compound to eliminate in biogas. This review presents the main characteristics of sulfur-oxidizing chemotrophic bacteria that are the base of the biological transformation of H2S to innocuous products in biofilters. A survey of the existing biofiltration technologies in relation to H2S elimination is then presented followed by a review of the microbial ecology studies performed to date on biotrickling filter units for the treatment of H2S in biogas under aerobic and anoxic conditions. Full article
(This article belongs to the Special Issue Advances in Biogas Desulfurization)
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9 pages, 3928 KiB  
Article
Desulfurization of Biogas from a Closed Landfill under Acidic Conditions Deploying an Iron-Redox Biological Process
by Antonio Velasco, Mariana Franco-Morgado, Sergio Revah, Luis Alberto Arellano-García, Matías Manzano-Zavala and Armando González-Sánchez
ChemEngineering 2019, 3(3), 71; https://doi.org/10.3390/chemengineering3030071 - 07 Aug 2019
Cited by 3 | Viewed by 3150
Abstract
Desulfurization processes play an important role in the use of biogas in the emerging market of renewable energy. In this study, an iron-redox biological process was evaluated at bench scale and pilot scale to remove hydrogen sulfide (H2S) from biogas. The [...] Read more.
Desulfurization processes play an important role in the use of biogas in the emerging market of renewable energy. In this study, an iron-redox biological process was evaluated at bench scale and pilot scale to remove hydrogen sulfide (H2S) from biogas. The pilot scale system performance was assessed with real biogas emitted from a closed landfill to determine the desulfurization capacity under outdoor conditions. The system consisted of an Absorption Bubble Column (ABC) and a Biotrickling Filter (BTF) with useful volumes of 3 L and 47 L, respectively. An acidophilic mineral-oxidizing bacterial consortium immobilized in polyurethane foam was utilized to regenerate Fe(III) ion, which in turn accomplished the continuous H2S removal from inlet biogas. The H2S removal efficiencies were higher than 99.5% when H2S inlet concentrations were 120–250 ppmv, yielding a treated biogas with H2S < 2 ppmv. The ferrous iron oxidation rate (0.31 g·L−1·h−1) attained when the system was operating in natural air convection mode showed that the BTF can operate without pumping air. A brief analysis of the system and the economic aspects are briefly analyzed. Full article
(This article belongs to the Special Issue Advances in Biogas Desulfurization)
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11 pages, 7184 KiB  
Article
Predictive Modeling of Corrosion in Al/Mg Dissimilar Joint
by Seyedsaied Ahmadvand, Mohammadreza Elahifard, Bijan Peik, Reza Behjatmanesh-Ardakani, Behrooz Abbasi and Bahman Abbasi
ChemEngineering 2019, 3(3), 70; https://doi.org/10.3390/chemengineering3030070 - 05 Aug 2019
Cited by 2 | Viewed by 2853
Abstract
In the absence of any abnormality (standard conditions), the gradient of any mechanical/thermodynamic stress would be intensified at the dissimilar joint due to an abrupt change in the chemical composition. This paper aims to investigate the effect of delocalizing this stress by imposing [...] Read more.
In the absence of any abnormality (standard conditions), the gradient of any mechanical/thermodynamic stress would be intensified at the dissimilar joint due to an abrupt change in the chemical composition. This paper aims to investigate the effect of delocalizing this stress by imposing an optimum chemical gradient within the dissimilar joint. In this work, we computationally demonstrated that a homogenous distribution of magnesium atoms in the aluminum (100) structure with a specific chemical gradient could potentially reduce the susceptibility of the Mg/Al dissimilar joint towards micro-galvanic corrosion. This is achieved through the minimization of the work function gradient within the dissimilar joint. Full article
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11 pages, 785 KiB  
Article
Selection of Optimum Separation Sequence for Multicomponent Distillation
by Anatoly Tsirlin, Ivan Sukin and Alexander Balunov
ChemEngineering 2019, 3(3), 69; https://doi.org/10.3390/chemengineering3030069 - 02 Aug 2019
Cited by 5 | Viewed by 3162
Abstract
This paper considers the process of multicomponent distillation. It is shown that energy consumption (per mole of mixture being separated) depends monotonously on efficiency if the capacity is constant and separation is reversible. Authors suggest the technique for selection of distillation sequence for [...] Read more.
This paper considers the process of multicomponent distillation. It is shown that energy consumption (per mole of mixture being separated) depends monotonously on efficiency if the capacity is constant and separation is reversible. Authors suggest the technique for selection of distillation sequence for which the total energy consumption in the cascade of columns reaches its minimum. This sequence is determined by values of thermal coefficients. Coefficients themselves depend on temperatures in the reboiler and condenser. This paper offers the algorithm for the calculation of these coefficients. Full article
(This article belongs to the Special Issue Progress in Thermal Process Engineering)
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22 pages, 8293 KiB  
Review
Preparation of Layered Double Hydroxides toward Precisely Designed Hierarchical Organization
by Rattanawadee (Ploy) Wijitwongwan, Soontaree (Grace) Intasa-ard and Makoto Ogawa
ChemEngineering 2019, 3(3), 68; https://doi.org/10.3390/chemengineering3030068 - 01 Aug 2019
Cited by 51 | Viewed by 10221
Abstract
Layered double hydroxides (LDHs) are a class of materials with useful properties associated with their anion exchange abilities for a wide range of materials’ applications including adsorbent, catalyst and its support, ceramic precursor, and drug carrier. In order to satisfy the requirements for [...] Read more.
Layered double hydroxides (LDHs) are a class of materials with useful properties associated with their anion exchange abilities for a wide range of materials’ applications including adsorbent, catalyst and its support, ceramic precursor, and drug carrier. In order to satisfy the requirements for the detailed characterization and the practical application, the preparation of LDHs with varied composition and particle morphology has been examined extensively. The versatility of the preparation methods led LDHs with varied composition and micro/macroscopic morphology, which makes the application of LDHs more realistic. In the present review article, synthetic methods of LDHs are overviewed in order to highlight the present status of the LDHs for practical application. Full article
(This article belongs to the Special Issue Advanced Applications of Layered Double Hydroxides)
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11 pages, 1526 KiB  
Article
Application of Sodium Dodecyl Sulfate/Activated Carbon onto the Preconcentration of Cadmium Ions in Solid-Phase Extraction Flow System
by Mai Furukawa, Ikki Tateishi, Hideyuki Katsumata and Satoshi Kaneco
ChemEngineering 2019, 3(3), 67; https://doi.org/10.3390/chemengineering3030067 - 01 Aug 2019
Cited by 3 | Viewed by 3224
Abstract
In the present study, activated carbon (AC) surface modified with sodium dodecyl sulfate (SDS), written as SDS/AC, was applied as an adsorbent for preconcentration and determination of trace amount of cadmium ions in environmental sample waters. The SDS modification on AC was performed [...] Read more.
In the present study, activated carbon (AC) surface modified with sodium dodecyl sulfate (SDS), written as SDS/AC, was applied as an adsorbent for preconcentration and determination of trace amount of cadmium ions in environmental sample waters. The SDS modification on AC was performed at the same time, while cadmium ions were concentrated in the flow system as solid-phase extraction. After the separation and preconcentration steps, cadmium retained on SDS/AC was eluted with HNO3 and was subsequently determined by flame atomic absorption spectrometry (FAAS). The analytical parameters that influence the quantitative determination of trace cadmium, such as SDS concentration, pH and volume of sample solution, eluent conditions, and interference, were optimized. At the optimum conditions, the general matrix elements had little interference on the proposed procedure. The detection limits was 17 ng·L−1, and the relative standard deviation (RSD) for 12 experiments at 10 µg·L−1 cadmium solutions was 2.8%. The developed method was applied into the analysis of environmental samples spiked cadmium. Full article
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12 pages, 2875 KiB  
Article
Application of Response Surface Methodology for H2S Removal from Biogas by a Pilot Anoxic Biotrickling Filter
by Fernando Almenglo, Martín Ramírez and Domingo Cantero
ChemEngineering 2019, 3(3), 66; https://doi.org/10.3390/chemengineering3030066 - 13 Jul 2019
Cited by 4 | Viewed by 3665
Abstract
In this study, a pilot biotrickling filter (BTF) was installed in a wastewater treatment plant to treat real biogas. The biogas flow rate was between 1 and 5 m3·h−1 with an H2S inlet load (IL) between [...] Read more.
In this study, a pilot biotrickling filter (BTF) was installed in a wastewater treatment plant to treat real biogas. The biogas flow rate was between 1 and 5 m3·h−1 with an H2S inlet load (IL) between 35.1 and 172.4 gS·m−3·h−1. The effects of the biogas flow rate, trickling liquid velocity (TLV) and nitrate concentration on the outlet H2S concentration and elimination capacity (EC) were studied using a full factorial design (33). Moreover, the results were adjusted using Ottengraf’s model. The most influential factors in the empirical model were the TLV and H2S IL, whereas the nitrate concentration had less influence. The statistical results showed high predictability and good correlation between models and the experimental results. The R-squared was 95.77% and 99.63% for the ‘C model’ and the ‘EC model’, respectively. The models allowed the maximum H2S IL (between 66.72 and 119.75 gS·m−3·h−1) to be determined for biogas use in a combustion engine (inlet H2S concentration between 72 and 359 ppmV). The ‘C model’ was more sensitive to TLV (–0.1579 (gS·m−3)/(m·h−1)) in the same way the ‘EC model’ was also more sensitive to TLV (4.3303 (gS·m−3)/(m·h−1)). The results were successfully fitted to Ottengraf’s model with a first-order kinetic limitation (R-squared above 0.92). Full article
(This article belongs to the Special Issue Advances in Biogas Desulfurization)
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19 pages, 3256 KiB  
Article
Insights from Mathematical Modelling into Energy Requirement and Process Design of Continuous and Batch Stirred Tank Aerobic Bioreactors
by John J. Fitzpatrick
ChemEngineering 2019, 3(3), 65; https://doi.org/10.3390/chemengineering3030065 - 13 Jul 2019
Cited by 6 | Viewed by 3653
Abstract
Bioreaction kinetics, oxygen transfer and energy modelling were applied to stirred tank aerobic bioreactors. This was done to investigate how key input design variables influence bioreactor size, feed and wasted substrate, and electrical energy requirements for aeration and cooling, and to compare batch [...] Read more.
Bioreaction kinetics, oxygen transfer and energy modelling were applied to stirred tank aerobic bioreactors. This was done to investigate how key input design variables influence bioreactor size, feed and wasted substrate, and electrical energy requirements for aeration and cooling, and to compare batch and continuous modes of operation. Oxygen concentration in the liquid is a key input design variable, but its selection is challenging as it can result in design trade-offs. Reducing its value caused a decrease in electrical energy requirement, however this tended to increase the working volume of the bioreactor. The minimum or near-to-minimum total energy requirement for oxygen transfer occurred when operating at the onset of flooding throughout the bioreaction time. For typical KS values, continuous mode of operation required a much smaller bioreactor volume, due to higher operating cell concentration, and this is a major advantage of continuous over batch. Full article
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11 pages, 405 KiB  
Article
Solubility Models for the Recovery of Rosmarinic Acid from Orthosiphon Aristatus Extract Using Solid Phase Extraction
by Cher Haan Lau and Lee Suan Chua
ChemEngineering 2019, 3(3), 64; https://doi.org/10.3390/chemengineering3030064 - 10 Jul 2019
Cited by 3 | Viewed by 3941
Abstract
Hildebrand and Hansen solubility parameters, and log P value are widely used to determine the solubility of polymers in solvents. The models were used to explain the recovery of phytochemical, rosmarinic acid from Orthosiphon aristatus extract in C18 solid phase extraction (SPE) using [...] Read more.
Hildebrand and Hansen solubility parameters, and log P value are widely used to determine the solubility of polymers in solvents. The models were used to explain the recovery of phytochemical, rosmarinic acid from Orthosiphon aristatus extract in C18 solid phase extraction (SPE) using the eluent consisting of ethyl acetate and chloroform in the decreasing polarity of solvent system. The experimental recovery of rosmarinic acid appeared to be well explained by the Hansen solubility model. The small difference in the Hansen solubility parameters, particularly for dispersion and hydrogen bonding forces, results in a higher polar solvent system for high rosmarinic acid recovery. The results found that the Hansen solubility model fitted well to the recovery of rosmarinic acid from crude extract with high coefficient of determination (R2 > 0.8), low standard error (4.4%), and p < 0.05. Hildebrand solubility is likely to be the second fit model, whereas log P has poor R2 < 0.7 and higher standard error (7.3%). The Hansen solubility model describes the interaction of solute–solvent in three dimensions (dispersion, polar, and hydrogen bonding forces) which can accurately explain the recovery of rosmarinic acid. Therefore, Hansen solubility can be used to predict the recovery of rosmarinic acid from O. aristatus extract using SPE. Full article
(This article belongs to the Special Issue Modelling, Simulation and Optimization of Large Scale Chemical Processes)
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28 pages, 6106 KiB  
Review
Metal Oxides Applied to Thermochemical Water-Splitting for Hydrogen Production Using Concentrated Solar Energy
by Stéphane Abanades
ChemEngineering 2019, 3(3), 63; https://doi.org/10.3390/chemengineering3030063 - 04 Jul 2019
Cited by 76 | Viewed by 13639
Abstract
Solar thermochemical processes have the potential to efficiently convert high-temperature solar heat into storable and transportable chemical fuels such as hydrogen. In such processes, the thermal energy required for the endothermic reaction is supplied by concentrated solar energy and the hydrogen production routes [...] Read more.
Solar thermochemical processes have the potential to efficiently convert high-temperature solar heat into storable and transportable chemical fuels such as hydrogen. In such processes, the thermal energy required for the endothermic reaction is supplied by concentrated solar energy and the hydrogen production routes differ as a function of the feedstock resource. While hydrogen production should still rely on carbonaceous feedstocks in a transition period, thermochemical water-splitting using metal oxide redox reactions is considered to date as one of the most attractive methods in the long-term to produce renewable H2 for direct use in fuel cells or further conversion to synthetic liquid hydrocarbon fuels. The two-step redox cycles generally consist of the endothermic solar thermal reduction of a metal oxide releasing oxygen with concentrated solar energy used as the high-temperature heat source for providing reaction enthalpy; and the exothermic oxidation of the reduced oxide with H2O to generate H2. This approach requires the development of redox-active and thermally-stable oxide materials able to split water with both high fuel productivities and chemical conversion rates. The main relevant two-step metal oxide systems are commonly based on volatile (ZnO/Zn, SnO2/SnO) and non-volatile redox pairs (Fe3O4/FeO, ferrites, CeO2/CeO2−δ, perovskites). These promising hydrogen production cycles are described by providing an overview of the best performing redox systems, with special focus on their capabilities to produce solar hydrogen with high yields, rapid reaction rates, and thermochemical performance stability, and on the solar reactor technologies developed to operate the solid–gas reaction systems. Full article
(This article belongs to the Special Issue Concentrated Solar Energy for Materials)
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12 pages, 13186 KiB  
Article
High-Power Ultrasonic Synthesis and Magnetic-Field-Assisted Arrangement of Nanosized Crystallites of Cobalt-Containing Layered Double Hydroxides
by Andrei N. Salak, Daniel E. L. Vieira, Irina M. Lukienko, Yuriy O. Shapovalov, Alexey V. Fedorchenko, Elena L. Fertman, Yurii G. Pashkevich, Roman Yu. Babkin, Aleksandr D. Shilin, Vasili V. Rubanik, Mário G. S. Ferreira and Joaquim M. Vieira
ChemEngineering 2019, 3(3), 62; https://doi.org/10.3390/chemengineering3030062 - 04 Jul 2019
Cited by 9 | Viewed by 3432
Abstract
High-quality stoichiometric Co2Al–NO3 and Co2Al–CO3 layered double hydroxides (LDHs) have been obtained by precipitation followed by anion exchange, both high-power-sonication assisted. Application of high-power ultrasound has been demonstrated to result in a considerable acceleration of the crystallization [...] Read more.
High-quality stoichiometric Co2Al–NO3 and Co2Al–CO3 layered double hydroxides (LDHs) have been obtained by precipitation followed by anion exchange, both high-power-sonication assisted. Application of high-power ultrasound has been demonstrated to result in a considerable acceleration of the crystallization process and the anion-exchange reaction. Two independent approaches were used to form bulk and 2-D samples of Co2Al–NO3 with the oriented crystallites, namely uniaxial pressing of deposits from sonicated LDH slurries and magnetic field-assisted arrangement of LDH crystallites precipitating on glass substrates. A convenient way of preparation of semi-transparent compacts with relatively big blocks of oriented crystallites have been demonstrated. Thin dense transparent films of highly-ordered crystallites of Co2Al–NO3 LDH have been produced and characterized. Full article
(This article belongs to the Special Issue Advanced Applications of Layered Double Hydroxides)
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14 pages, 8394 KiB  
Article
Investigations on Cationic Dye Degradation Using Iron-Doped Carbon Xerogel
by S. Andrada Maicaneanu, Breanna McGhee, Razvan Stefan, Lucian Barbu-Tudoran, Christopher Sedwick and Charles H. Lake
ChemEngineering 2019, 3(3), 61; https://doi.org/10.3390/chemengineering3030061 - 04 Jul 2019
Cited by 4 | Viewed by 3270
Abstract
Iron-doped carbon xerogels were prepared using sol-gel synthesis, with potassium-2,4-dihydroxybenzoate and formaldehyde as starting materials, followed by an ion exchange step. The obtained samples were characterized (XRD, FTIR, SED-EDX, TEM) and investigated as catalysts in heterogeneous Fenton and catalytic wet air oxidation (CWAO) [...] Read more.
Iron-doped carbon xerogels were prepared using sol-gel synthesis, with potassium-2,4-dihydroxybenzoate and formaldehyde as starting materials, followed by an ion exchange step. The obtained samples were characterized (XRD, FTIR, SED-EDX, TEM) and investigated as catalysts in heterogeneous Fenton and catalytic wet air oxidation (CWAO) processes. Experiments were conducted in the same conditions (0.1 g catalysts, 25 mL of 100 mg/L dye solution, 25 °C, initial solution pH, 3 h) in thermostated batch reaction tubes (shaking water bath, 50 rpm) at atmospheric pressure. A series of three cationic dyes were considered: Brilliant green (BG), crystal violet (CV), and methyl green (MG). Dyes and TOC removal efficiencies up to 99% and 92%, respectively, were obtained, in strong correlation with the iron content of the catalyst. Iron content measured in solution at the end of the reaction, indicated that its amount was less than 2 ppm for all tested catalysts. Full article
(This article belongs to the Special Issue Synthesis of Carbon Nanomaterials and Carbon Nanomaterial–Metal(Oxide) Composites and Their Applications in Catalysis)
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15 pages, 4507 KiB  
Article
ZIF-8 as a Catalyst in Ethylene Oxide and Propylene Oxide Reaction with CO2 to Cyclic Organic Carbonates
by Jenny G. Vitillo, Valentina Crocellà and Francesca Bonino
ChemEngineering 2019, 3(3), 60; https://doi.org/10.3390/chemengineering3030060 - 02 Jul 2019
Cited by 10 | Viewed by 5101
Abstract
CO2 is an important by-product in epoxides synthesis, accounting for 0.02% of worldwide greenhouse emissions. The CO2 cycloaddition to ethylene and propylene oxides is an important class of reactions due to the versatile nature of the corresponding organic carbonates as chemical [...] Read more.
CO2 is an important by-product in epoxides synthesis, accounting for 0.02% of worldwide greenhouse emissions. The CO2 cycloaddition to ethylene and propylene oxides is an important class of reactions due to the versatile nature of the corresponding organic carbonates as chemical feedstocks. We report that these reactions can be catalyzed by ZIF-8 (Zeolitic Imidazole Framework-8) in the absence of solvent or co-catalyst and in mild conditions (40 °C and 750 mbar). In situ infrared spectroscopy places the onset time for ethylene and propylene carbonate formation to 80 and 30 min, respectively. Although there is low catalytic activity, these findings suggest the possibility to cut the CO2 emissions from epoxides production through their direct conversion to these highly valuable chemical intermediates, eliminating de facto energetically demanding steps as the CO2 capture and storage. Full article
(This article belongs to the Special Issue CO2 Capture, Utilization, and Storage)
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