Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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20 pages, 3266 KiB  
Article
A Framework for Upscaling of Emerging Chemical Processes Based on Thermodynamic Process Modeling and Simulation
by Hafiz Farooq Imtiaz
ChemEngineering 2024, 8(3), 46; https://doi.org/10.3390/chemengineering8030046 - 1 May 2024
Viewed by 1142
Abstract
Prospective environmental and technological assessment of emerging chemical processes is necessary to identify, analyze and evaluate the technologies that are highly imperative in the transition towards climate neutrality. The investigation of the environmental impacts and material and energy requirements of the processes at [...] Read more.
Prospective environmental and technological assessment of emerging chemical processes is necessary to identify, analyze and evaluate the technologies that are highly imperative in the transition towards climate neutrality. The investigation of the environmental impacts and material and energy requirements of the processes at the low technology readiness level (TRL) is important in making early decisions about the feasibility of adapting and upscaling the process to the industrial level. However, the upscaling of new chemical processes has always been a major challenge; and in this context, there is no general methodological guidance available in the literature. Hence, a new comprehensive methodological framework for upscaling of novel chemical processes is designed and presented based on thermodynamic process modeling and simulation. The practical implementation of the proposed methodology is extensively discussed by developing a scaled-up novel carbon capture and utilization (CCU) process comprised of sequestration of carbon dioxide (CO2) from blast furnace gas with a capacity of 1000 liter per hour (L/h) using methanol and its utilization as a precursor to produce methane (CH4). It was found that thermodynamic process modeling and simulations based on the perturbed-chain statistical associating (PC-SAFT) equation of state (EOS) can precisely estimate the CO2 solubility in methanol and conversion to CH4 at various temperature and pressure conditions. The achieved thermophysical property and kinetics parameters can be employed in process simulations to estimate scaled-up environmental flows and material and energy requirements of the process. Full article
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15 pages, 2952 KiB  
Article
Experimental Study on the Reaction of Magnesium in Carbon Dioxide and Nitrogen Atmosphere
by Ioan Barabulica, Marius Sebastian Secula, Adriana Mariana Asoltanei, Eugenia Teodora Iacob-Tudose, Gabriela Lisa and Ioan Mamaliga
ChemEngineering 2024, 8(2), 41; https://doi.org/10.3390/chemengineering8020041 - 6 Apr 2024
Viewed by 1364
Abstract
This manuscript presents an experimental study focusing on the combustion of magnesium in an atmosphere depleted of oxygen. The study explores various mixtures of carbon dioxide and nitrogen, examining their impact on the combustion performance. The experimental design involved evaluating how the carbon [...] Read more.
This manuscript presents an experimental study focusing on the combustion of magnesium in an atmosphere depleted of oxygen. The study explores various mixtures of carbon dioxide and nitrogen, examining their impact on the combustion performance. The experimental design involved evaluating how the carbon content influences combustion parameters. Temperature profiles were analyzed to elucidate different stages of the combustion process. Furthermore, the effects of pressure (2 and 3 ata) and the composition of CO2-N2 mixtures (10%, 19.5%, 35%, 48%, 72%, and 80% CO2 content) on magnesium combustion, including ignition time, maximum temperature, and post-combustion temperatures, were investigated. The results revealed a substantial impact on the ignition delay and combustion time, with the ignition delay decreasing with higher chamber pressure. The combustion process, especially with regard to the ignition time and heat of combustion, was notably affected by CO2 concentration. The morphology of the combustion residue from the magnesium microparticles was characterized using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDX). The reaction of Mg with CO2 represents a promising energy source, quickly releasing a substantial amount of heat with a very low quantity of Mg. The estimated value of the heat of combustion for magnesium in N2-CO2 atmosphere is 78.4 kJ mol−1. Full article
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12 pages, 3032 KiB  
Article
Novel Bi-Functional MoS2/α-Fe2O3 Nanocomposites for High Photocatalytic Performance
by Islam Ibrahim, Pinelopi P. Falara, Elias Sakellis, Maria Antoniadou, Chrysoula Athanasekou and Michalis K. Arfanis
ChemEngineering 2024, 8(1), 20; https://doi.org/10.3390/chemengineering8010020 - 6 Feb 2024
Cited by 1 | Viewed by 1612
Abstract
In this study, 3-dimensional molybdenum disulfide (MoS2) structures, integrated with hematite (α-Fe2O3) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS2 flakes, resembling spherical flower-like morphology, and the [...] Read more.
In this study, 3-dimensional molybdenum disulfide (MoS2) structures, integrated with hematite (α-Fe2O3) nanoparticles, were fabricated under a convenient two-step hydrothermal route. The fabricated photocatalytic nanocomposites consist of well-arranged MoS2 flakes, resembling spherical flower-like morphology, and the nanoparticulate α-Fe2O3 structures decorate the 3D network. By raising the α-Fe2O3 weight ratio, the composites’ specific surface area and morphology were not affected, regardless of the partial cover of the cavities for higher hematite content. Moreover, the crystallinity examination with XRD, Raman, and FTIR techniques revealed that the precursor reagents were fully transformed to well-crystalized MoS2 and Fe2O3 composites of high purity, as no organic or inorganic residues could be detected. The photocatalytic oxidation and reduction performance of these composites was evaluated against the tetracycline pharmaceutical and the industrial pollutant hexavalent chromium, respectively. The improvement in the removal efficiencies demonstrates that the superior photoactivity originates from the high crystallinity and homogeneity of the composite, in combination with the enhanced charge carriers’ separation in the semiconductors’ interface. Full article
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17 pages, 1445 KiB  
Review
Innovations in Modern Nanotechnology for the Sustainable Production of Agriculture
by Rajiv Periakaruppan, Valentin Romanovski, Selva Kumar Thirumalaisamy, Vanathi Palanimuthu, Manju Praveena Sampath, Abhirami Anilkumar, Dinesh Kumar Sivaraj, Nihaal Ahamed Nasheer Ahamed, Shalini Murugesan, Divya Chandrasekar and Karungan Selvaraj Vijai Selvaraj
ChemEngineering 2023, 7(4), 61; https://doi.org/10.3390/chemengineering7040061 - 12 Jul 2023
Cited by 7 | Viewed by 4164
Abstract
Nanotechnology has an extensive series of applications in agronomy and has an important role in the future of sustainable agriculture. The agricultural industries should be supported by innovative active materials such as nanofertilizers, nanofungicides, and nanopesticides. It is necessary in the current situation [...] Read more.
Nanotechnology has an extensive series of applications in agronomy and has an important role in the future of sustainable agriculture. The agricultural industries should be supported by innovative active materials such as nanofertilizers, nanofungicides, and nanopesticides. It is necessary in the current situation to meet the dietary needs of the constantly expanding world population. Nearly one-third of crops grown conventionally suffer damage, mostly as a result of pest infestation, microbiological assaults, natural disasters, poor soil quality, and a lack of nutrients. To solve these problems, we urgently need more inventive technology. The application of nanotechnology in agriculture provides intelligent methods for delivering nutrients, herbicides, and genetic materials for improving soil fertility, stress tolerance, and protection. The world is currently confronting significant issues related to the rising demand for enough food and safe food as well as dealing with the environmental damage caused by traditional agriculture. Nanomaterials have important applications in agriculture for increasing plant growth and development and the quality and quantity of the crops and controlling and managing agricultural diseases. The major objective of this article is to describe the various applications and importance of nanoparticles in the agriculture sector. Full article
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20 pages, 3819 KiB  
Review
A Brief Review of Photocatalytic Reactors Used for Persistent Pesticides Degradation
by Gabriela Olimpia Isopencu, Alexandra Mocanu and Iuliana-Mihaela Deleanu
ChemEngineering 2022, 6(6), 89; https://doi.org/10.3390/chemengineering6060089 - 11 Nov 2022
Cited by 5 | Viewed by 3256
Abstract
Pesticide pollution is a major issue, given their intensive use in the 20th century, which led to their accumulation in the environment. At the international level, strict regulations are imposed on the use of pesticides, simultaneously with the increasing interest of researchers from [...] Read more.
Pesticide pollution is a major issue, given their intensive use in the 20th century, which led to their accumulation in the environment. At the international level, strict regulations are imposed on the use of pesticides, simultaneously with the increasing interest of researchers from all over the world to find methods of neutralizing them. Photocatalytic degradation is an intensively studied method to be applied for the degradation of pesticides, especially through the use of solar energy. The mechanisms of photocatalysis are studied and implemented in pilot and semi-pilot installations on experimental platforms, in order to be able to make this method more efficient and to identify the equipment that can achieve the photodegradation of pesticides with the highest possible yields. This paper proposes a brief review of the impact of pesticides on the environment and some techniques for their degradation, with the main emphasis on different photoreactor configurations, using slurry or immobilized photocatalysts. This review highlights the efforts of researchers to harmonize the main elements of photocatalysis: choice of the photocatalyst, and the way of photocatalyst integration within photoreaction configuration, in order to make the transfer of momentum, mass, and energy as efficient as possible for optimal excitation of the photocatalyst. Full article
(This article belongs to the Special Issue Photocatalytic Degradation of Organic Wastes)
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12 pages, 2752 KiB  
Article
Preliminary Study on Characteristics of NC/HTPB-Based High-Energy Gun Propellants
by Yi-Hsien Lin, Tsung-Mao Yang, Jin-Shuh Li, Kai-Tai Lu and Tsao-Fa Yeh
ChemEngineering 2022, 6(5), 80; https://doi.org/10.3390/chemengineering6050080 - 10 Oct 2022
Cited by 1 | Viewed by 1901
Abstract
This study mainly explored the characteristics of NC/HTPB-based high-energy gun propellants with RDX, CL-20 or TKX-50 by experimental method. Three series of test samples were prepared referring to the formulation of M1 single-base gun propellant (M1 SBP). The thermochemical characteristics, chemical stability, explosion [...] Read more.
This study mainly explored the characteristics of NC/HTPB-based high-energy gun propellants with RDX, CL-20 or TKX-50 by experimental method. Three series of test samples were prepared referring to the formulation of M1 single-base gun propellant (M1 SBP). The thermochemical characteristics, chemical stability, explosion heat, impact and friction sensitivities of prepared samples were determined by simultaneous differential scanning calorimetry–thermogravimetric analysis (STA DSC–TGA), vacuum stability tester (VST), bomb calorimeter (BC), BAM fallhammer and BAM friction tester, respectively, and compared with those of the reference sample M1. The experimental results indicated that the thermochemical characteristics of NC/HTPB-based high-energy gun propellants were similar to those of M1 SBP. The NC/HTPB-based high-energy gun propellants had good chemical stability and were superior to M1 SBP. The explosion heat of NC/HTPB-based high-energy gun propellants was close to and slightly larger than that of M1 SBP. In addition, the NC/HTPB-based high-energy gun propellants had lower impact and friction sensitivities than the M1 SBP. Therefore, the NC/HTPB-based high-energy gun propellants have the potential to replace the M1 SBP. The combustion performances of NC/HTPB-based high-energy gun propellants will be continuously studied and verified in the future. Full article
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16 pages, 1361 KiB  
Article
30 Years of Vicente Rives’ Contribution to Hydrotalcites, Synthesis, Characterization, Applications, and Innovation
by Raquel Trujillano
ChemEngineering 2022, 6(4), 60; https://doi.org/10.3390/chemengineering6040060 - 1 Aug 2022
Cited by 6 | Viewed by 2251
Abstract
Hydrotalcite is the name of a mineral discovered in Sweden in 1842 whose formula is Mg6Al2(OH)16CO3·4H2O and presents a layered crystal structure that consists of positively charged hydroxide layers neutralized by interlayer anions [...] Read more.
Hydrotalcite is the name of a mineral discovered in Sweden in 1842 whose formula is Mg6Al2(OH)16CO3·4H2O and presents a layered crystal structure that consists of positively charged hydroxide layers neutralized by interlayer anions as carbonate, also containing water molecules. The ease of their synthesis and the possibility of incorporating other layer cations and interlayer anions have made this type of layered double hydroxides (LDH) a group of very interesting materials for industry. In addition to LDH and due to the name of the most representative mineral, this group of compounds is commonly called hydrotalcite-like materials, or simply hydrotalcites. Another way of referring to them is as anionic clays because of their layered structure but, unlike classical clays, their layers are positive and their interlayers are anionic. The main fields of application of these solids comprise catalysis, catalyst support, anion scavengers, polymer stabilizers, drug carriers, or adsorbents. This paper briefly summarizes some of the work carried out by Professor Rives over more than thirty years, focused, among other topics, on the study of the synthesis, characterization, and applications of hydrotalcites. This research has led him to train many researchers, to collaborate with research groups around the world and to publish reference papers and books in this field. This contribution, written to be included in the Special Issue “A Themed Issue in Honor of Prof. Dr. Vicente Rives”, edited on the occasion of his retirement, only shows a small part of his scientific research and intends to value and recognize his cleverness and his enormous scientific and human quality. Full article
(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)
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51 pages, 4812 KiB  
Review
Catalytic Steam Reforming of Biomass-Derived Oxygenates for H2 Production: A Review on Ni-Based Catalysts
by Joel Silva, Cláudio Rocha, M. A. Soria and Luís M. Madeira
ChemEngineering 2022, 6(3), 39; https://doi.org/10.3390/chemengineering6030039 - 27 May 2022
Cited by 4 | Viewed by 2854
Abstract
The steam reforming of ethanol, methanol, and other oxygenates (e.g., bio-oil and olive mill wastewater) using Ni-based catalysts have been studied by the scientific community in the last few years. This process is already well studied over the last years, being the critical [...] Read more.
The steam reforming of ethanol, methanol, and other oxygenates (e.g., bio-oil and olive mill wastewater) using Ni-based catalysts have been studied by the scientific community in the last few years. This process is already well studied over the last years, being the critical point, at this moment, the choice of a suitable catalyst. The utilization of these oxygenates for the production of “green” H2 is an interesting alternative to fuel fossils. For this application, Ni-based catalysts have been extensively studied since they are highly active and cheaper than noble metal-based materials. In this review, a comparison of several Ni-based catalysts reported in the literature for the different above-mentioned reactions is carried out. This study aims to understand if such catalysts demonstrate enough catalytic activity/stability for application in steam reforming of the oxygenated compounds and which preparation methods are most adequate to obtain these materials. In summary, it aims to provide insights into the performances reached and point out the best way to get better and improved catalysts for such applications (which depends on the feedstock used). Full article
(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)
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18 pages, 7328 KiB  
Review
Electrocatalysts for the Oxygen Reduction Reaction: From Bimetallic Platinum Alloys to Complex Solid Solutions
by Ricardo Martínez-Hincapié and Viktor Čolić
ChemEngineering 2022, 6(1), 19; https://doi.org/10.3390/chemengineering6010019 - 16 Feb 2022
Cited by 6 | Viewed by 4864
Abstract
The oxygen reduction reaction has been the object of intensive research in an attempt to improve the sluggish kinetics that limit the performance of renewable energy storage and utilization systems. Platinum or platinum bimetallic alloys are common choices as the electrode material, but [...] Read more.
The oxygen reduction reaction has been the object of intensive research in an attempt to improve the sluggish kinetics that limit the performance of renewable energy storage and utilization systems. Platinum or platinum bimetallic alloys are common choices as the electrode material, but prohibitive costs hamper their use. Complex alloy materials, such as high-entropy alloys (HEAs), or more generally, multiple principal component alloys (MPCAs), have emerged as a material capable of overcoming the limitations of platinum and platinum-based materials. Theoretically, due to the large variety of active sites, this new kind of material offers the opportunity to identify experimentally the optimal binding site on the catalyst surface. This review discusses recent advances in the application of such alloys for the oxygen reduction reaction and existing experimental challenges in the benchmarking of the electrocatalytic properties of these materials. Full article
(This article belongs to the Special Issue New Insights into Electrocatalysis)
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22 pages, 1781 KiB  
Review
Key Points of Advanced Oxidation Processes (AOPs) for Wastewater, Organic Pollutants and Pharmaceutical Waste Treatment: A Mini Review
by Pavlos K. Pandis, Charalampia Kalogirou, Eirini Kanellou, Christos Vaitsis, Maria G. Savvidou, Georgia Sourkouni, Antonis A. Zorpas and Christos Argirusis
ChemEngineering 2022, 6(1), 8; https://doi.org/10.3390/chemengineering6010008 - 18 Jan 2022
Cited by 151 | Viewed by 16669
Abstract
Advanced oxidation procedures (AOPs) refer to a variety of technical procedures that produce OH radicals to sufficiently oxidize wastewater, organic pollutant streams, and toxic effluents from industrial, hospital, pharmaceutical and municipal wastes. Through the implementation of such procedures, the (post) treatment of such [...] Read more.
Advanced oxidation procedures (AOPs) refer to a variety of technical procedures that produce OH radicals to sufficiently oxidize wastewater, organic pollutant streams, and toxic effluents from industrial, hospital, pharmaceutical and municipal wastes. Through the implementation of such procedures, the (post) treatment of such waste effluents leads to products that are more susceptible to bioremediation, are less toxic and possess less pollutant load. The basic mechanism produces free OH radicals and other reactive species such as superoxide anions, hydrogen peroxide, etc. A basic classification of AOPs is presented in this short review, analyzing the processes of UV/H2O2, Fenton and photo-Fenton, ozone-based (O3) processes, photocatalysis and sonolysis from chemical and equipment points of view to clarify the nature of the reactive species in each AOP and their advantages. Finally, combined AOP implementations are favored through the literature as an efficient solution in addressing the issue of global environmental waste management. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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11 pages, 1592 KiB  
Article
Kinetics of Simultaneous Ammonium and Phosphate Recovery by Natural Zeolite
by Sandro Pesendorfer and Markus Ellersdorfer
ChemEngineering 2021, 5(4), 68; https://doi.org/10.3390/chemengineering5040068 - 8 Oct 2021
Cited by 1 | Viewed by 2470
Abstract
Nowadays, fertilizers containing nitrogen and phosphorus are indispensable for medium and large-scale industrial agriculture. To meet the growing demand of nutrients and reduce the accompanied ecological footprint of primary fertilizer production, processes and technologies for nutrient recovery are necessary and have to be [...] Read more.
Nowadays, fertilizers containing nitrogen and phosphorus are indispensable for medium and large-scale industrial agriculture. To meet the growing demand of nutrients and reduce the accompanied ecological footprint of primary fertilizer production, processes and technologies for nutrient recovery are necessary and have to be developed. This study represents the basis of an extension of the ion-exchange-loop-stripping process (ILS), which is a combined stripping and ion exchange process using natural zeolite for nitrogen recovery. In batch experiments with a special zeolite filled stirrer, the mechanism and kinetics of simultaneous ammonium and phosphate recovery by natural zeolite were determined. Zeolite loadings of 6.78 mg PO43− g−1 were reached and after regeneration, phosphate recovery rates up to 75% of the initial concentration were achieved. The speed of phosphate precipitation is mostly controlled by the pH value of synthetic wastewater. Phosphate removal in simultaneous experiments does not affect ammonium sorption onto zeolite. These findings and the different removal mechanisms of ammonium and phosphate lead to versatile applications in wastewater treatment and reveal great potential of natural zeolite in simultaneous nutrient recovery processes. Full article
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24 pages, 3532 KiB  
Review
Graphene Oxide Synthesis, Properties and Characterization Techniques: A Comprehensive Review
by Dimitrios G. Trikkaliotis, Achilleas K. Christoforidis, Athanasios C. Mitropoulos and George Z. Kyzas
ChemEngineering 2021, 5(3), 64; https://doi.org/10.3390/chemengineering5030064 - 17 Sep 2021
Cited by 38 | Viewed by 9133
Abstract
The unique properties of graphene oxide (GO) have attracted the attention of the research community and cost-effective routes for its production are studied. The type and percentage of the oxygen groups that decorate a GO sheet are dependent on the synthesis path, and [...] Read more.
The unique properties of graphene oxide (GO) have attracted the attention of the research community and cost-effective routes for its production are studied. The type and percentage of the oxygen groups that decorate a GO sheet are dependent on the synthesis path, and this path specifies the carbon content of the sheet. The chemical reduction of GO results in reduced graphene oxide (rGO) while the removal of the oxygen groups is also achievable with thermal processes (tpGO). This review article introduces the reader to the carbon allotropes, provides information about graphene which is the backbone of GO and focuses on GO synthesis and properties. The last part covers some characterization techniques of GO (XRD, FTIR, AFM, SEM-EDS, N2 porosimetry and UV-Vis) with a view to the fundamental principles of each technique. Some critical aspects arise for GO synthesized and characterized from our group. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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22 pages, 8872 KiB  
Article
3-D Multi-Tubular Reactor Model Development for the Oxidative Dehydrogenation of Butene to 1,3-Butadiene
by Jiyoung Moon, Dela Quarme Gbadago and Sungwon Hwang
ChemEngineering 2020, 4(3), 46; https://doi.org/10.3390/chemengineering4030046 - 21 Jul 2020
Cited by 4 | Viewed by 5396
Abstract
The oxidative dehydrogenation (ODH) of butene has been recently developed as a viable alternative for the synthesis of 1,3-butadiene due to its advantages over other conventional methods. Various catalytic reactors for this process have been previously studied, albeit with a focus on lab-scale [...] Read more.
The oxidative dehydrogenation (ODH) of butene has been recently developed as a viable alternative for the synthesis of 1,3-butadiene due to its advantages over other conventional methods. Various catalytic reactors for this process have been previously studied, albeit with a focus on lab-scale design. In this study, a multi-tubular reactor model for the butadiene synthesis via ODH of butene was developed using computational fluid dynamics (CFD). For this, the 3D multi-tubular model, which combines complex reaction kinetics with a shell-side coolant fluid over a series of individual reactor tubes, was generated using OpenFOAM®. Then, the developed model was validated and analyzed with the experimental results, which gave a maximum error of 7.5%. Finally, parametric studies were conducted to evaluate the effect of thermodynamic conditions (isothermal, non-isothermal and adiabatic), feed temperature, and gas velocity on reactor performance. The results showed the formation of a hotspot at the reactor exit, which necessitates an efficient temperature control at that section of the reactor. It was also found that as the temperature increased, the conversion and yield increased whilst the selectivity decreased. The converse was found for increasing velocities. Full article
(This article belongs to the Special Issue Computational Fluid Dynamics (CFD) of Chemical Processes)
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11 pages, 1694 KiB  
Article
MnO2-Coated Dual Core–Shell Spindle-Like Nanorods for Improved Capacity Retention of Lithium–Sulfur Batteries
by Hamza Dunya, Maziar Ashuri, Dana Alramahi, Zheng Yue, Kamil Kucuk, Carlo U. Segre and Braja K. Mandal
ChemEngineering 2020, 4(2), 42; https://doi.org/10.3390/chemengineering4020042 - 19 Jun 2020
Cited by 9 | Viewed by 4892
Abstract
The emerging need for high-performance lithium–sulfur batteries has motivated many researchers to investigate different designs. However, the polysulfide shuttle effect, which is the result of dissolution of many intermediate polysulfides in electrolyte, has still remained unsolved. In this study, we have designed a [...] Read more.
The emerging need for high-performance lithium–sulfur batteries has motivated many researchers to investigate different designs. However, the polysulfide shuttle effect, which is the result of dissolution of many intermediate polysulfides in electrolyte, has still remained unsolved. In this study, we have designed a sulfur-filled dual core–shell spindle-like nanorod structure coated with manganese oxide (S@HCNR@MnO2) to achieve a high-performance cathode for lithium–sulfur batteries. The cathode showed an initial discharge capacity of 1661 mA h g−1 with 80% retention of capacity over 70 cycles at a 0.2C rate. Furthermore, compared with the nanorods without any coating (S@HCNR), the MnO2-coated material displayed superior rate capability, cycling stability, and Coulombic efficiency. The synergistic effects of the nitrogen-doped hollow carbon host and the MnO2 second shell are responsible for the improved electrochemical performance of this nanostructure. Full article
(This article belongs to the Special Issue Chemical Engineering and Multidisciplinary)
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9 pages, 986 KiB  
Article
Integrated and Networked Systems and Processes—A Perspective for Digital Transformation in Thermal Process Engineering
by Michael Maiwald
ChemEngineering 2020, 4(1), 15; https://doi.org/10.3390/chemengineering4010015 - 4 Mar 2020
Cited by 5 | Viewed by 2845
Abstract
Separation technology as a sub-discipline of thermal process engineering is one of the most critical steps in the production of chemicals, essential for the quality of intermediate and end products. The discipline comprises the construction of facilities that convert raw materials into value-added [...] Read more.
Separation technology as a sub-discipline of thermal process engineering is one of the most critical steps in the production of chemicals, essential for the quality of intermediate and end products. The discipline comprises the construction of facilities that convert raw materials into value-added products along the value chain. Conversions typically take place in repeated reaction and separation steps—either in batch or continuous processes. The end products are the result of several production and separation steps that are not only sequentially linked, but also include the treatment of unused raw materials, by-products and wastes. Production processes in the process industry are particularly susceptible to fluctuations in raw materials and other influences affecting product quality. This is a challenge, despite increasing fluctuations, to deliver targeted quality and simultaneously meet the increasing dynamics of the market, at least for high value fine chemicals. In order to survive successfully in a changed environment, chemical companies must tread new paths. This includes the potential of digital technologies. The full integration and intelligent networking of systems and processes is progressing hesitantly. This contribution aims to encourage a more holistic approach to the digitalization in thermal process engineering by introduction of integrated and networked systems and processes. Full article
(This article belongs to the Special Issue Progress in Thermal Process Engineering)
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8 pages, 3421 KiB  
Article
Flavor Release from Spray-Dried Powders with Various Wall Materials
by Shisei Takashige, Hermawan Dwi Ariyanto, Shuji Adachi and Hidefumi Yoshii
ChemEngineering 2020, 4(1), 1; https://doi.org/10.3390/chemengineering4010001 - 28 Dec 2019
Cited by 6 | Viewed by 3484
Abstract
By using the ramping method for humidity at a constant temperature, the release rates of d-limonene were investigated from spray-dried powders with various wall materials, such as maltodextrin (MD) (dextrose equivalent (DE) = 25 and 19), lactose (Lac), and sucrose (Suc). Spray-dried [...] Read more.
By using the ramping method for humidity at a constant temperature, the release rates of d-limonene were investigated from spray-dried powders with various wall materials, such as maltodextrin (MD) (dextrose equivalent (DE) = 25 and 19), lactose (Lac), and sucrose (Suc). Spray-dried powders, which were sieved to the average powder size of 107–140 µm, contained d-limonene at about 90–97 mg/g-dry powder. d-limonene release profile was measured using a dynamic vapor sorption (DVS) system coupled gas chromatography at 30, 40, and 50 °C from 10% to 90% relative humidity (RH). The linear correlation was found between the release start humidity, sRH, of d-limonene release from the powder and the glass transition temperature of wall materials. The release rates for Suc and Lac increased rapidly at certain humidities and became the maximum rates. Then, these rates decreased gradually with increasing RH. This might have been due to the powder aggregation for Suc and to crystallization for Lac. The release behaviors significantly depended on the wall materials. Full article
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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 - 2 Sep 2019
Cited by 68 | Viewed by 14441
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, 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 - 2 Jul 2019
Cited by 10 | Viewed by 5373
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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13 pages, 3051 KiB  
Article
Novel Photocatalytic NH3 Synthesis by NO3 Reduction over CuAg/TiO2
by Ryota Kato, Mai Furukawa, Ikki Tateishi, Hideyuki Katsumata and Satoshi Kaneco
ChemEngineering 2019, 3(2), 49; https://doi.org/10.3390/chemengineering3020049 - 8 May 2019
Cited by 13 | Viewed by 5370
Abstract
The highly effective reaction system was investigated for the photocatalytic ammonia synthesis from the reduction of nitrate ions by using the semiconductor photocatalyst, Cu and Ag doped on TiO2 (CuAg/TiO2) at room temperature under UV light irradiation (max. 352 nm). [...] Read more.
The highly effective reaction system was investigated for the photocatalytic ammonia synthesis from the reduction of nitrate ions by using the semiconductor photocatalyst, Cu and Ag doped on TiO2 (CuAg/TiO2) at room temperature under UV light irradiation (max. 352 nm). In this study, CuAg/TiO2 gave the high efficiency and the selectivity for the ammonia synthesis by the photoreduction of nitrate in the presence of methanol as a hole scavenger. For the evaluation of the photocatalytic activity over CuAg/TiO2, various TiO2 samples, such as standard TiO2, Cu/TiO2, and Ag/TiO2, were evaluated in the same procedure. The chemical properties were investigated by XRD, TEM, XPS, PL, and DRS. We examined the optimum conditions for the experimental factors and the important issues, including the effect of the molar ratio of Cu and Ag onto TiO2, the optimization of the CuAg amount loaded on TiO2, the influence of the loading amount of the catalyst on the reduction of nitrate ions, the exploration of the optimum hole scavenger, and the reusability of the optimum photocatalyst. The very efficient conversion of nitrate ions (95%) and the highest selectivity (86%) were achieved in the reaction with the optimum conditions. Here, we reported the process that nitrate ions can efficiently be reduced, and ammonia can be selectively synthesized over CuAg/TiO2. Full article
(This article belongs to the Special Issue Advances in Metal-Based Catalysts)
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12 pages, 4610 KiB  
Article
Layered Double Hydroxides for the Catalytic Isomerization of Linoleic Acid to Conjugated Linoleic Acids (CLAs)
by Xavier Cardó, Pilar Salagre and Yolanda Cesteros
ChemEngineering 2019, 3(1), 30; https://doi.org/10.3390/chemengineering3010030 - 10 Mar 2019
Cited by 2 | Viewed by 2829
Abstract
Several hydrotalcite-type compounds with different divalent (Mg2+, Ni2+, Cu2+, Zn2+) and trivalent (Al3+, Cr3+) cations and different ratio compositions were tested for the isomerization of linoleic acid in order to study [...] Read more.
Several hydrotalcite-type compounds with different divalent (Mg2+, Ni2+, Cu2+, Zn2+) and trivalent (Al3+, Cr3+) cations and different ratio compositions were tested for the isomerization of linoleic acid in order to study their role on the obtention of specific conjugated linoleic acids (CLAs) with anticarcinogenic and nutritional properties. This is a complex reaction due to the high number of possible isomers of linoleic acid together with the significant competition of the isomerization reaction with other secondary undesired reactions. All catalysts showed very high conversions of linoleic acid, but condensation products were mainly obtained, especially for the hydrotalcite-type compounds with higher Mg/Al ratios due to their higher Brønsted basicity and for the catalysts with higher Ni2+ content or with the presence of Cu2+, Zn2+ in the layers because of the influence of the higher acidity of these cations on the Brønsted basicity of the hydroxides. The best results were achieved for the catalysts with Mg/Al ratio around 2.5–3, resulting in 29–38% of selectivity to the identified CLAs. Full article
(This article belongs to the Special Issue Advanced Applications of Layered Double Hydroxides)
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18 pages, 12756 KiB  
Article
CNT and H2 Production during CH4 Decomposition over Ni/CeZrO2. II. Catalyst Performance and Its Regeneration in a Fluidized Bed
by Agata Łamacz and Grzegorz Łabojko
ChemEngineering 2019, 3(1), 25; https://doi.org/10.3390/chemengineering3010025 - 5 Mar 2019
Cited by 13 | Viewed by 5616
Abstract
In this work, a ceria-zirconia supported nickel catalyst (Ni/CeZrO2) was for the first time used in a fluidized bed reactor in order to obtain carbon nanotubes (CNTs) and H2 in the reaction of the decomposition of CH4. The [...] Read more.
In this work, a ceria-zirconia supported nickel catalyst (Ni/CeZrO2) was for the first time used in a fluidized bed reactor in order to obtain carbon nanotubes (CNTs) and H2 in the reaction of the decomposition of CH4. The same catalyst was afterward regenerated with H2O, which was accompanied with the production of H2. The impact of catalyst granulation, temperature, and gas hourly space velocity (GHSV) on the amount and type of carbon deposits was determined using thermogravimetric analysis (TGA) and scanning and transmission electron microscopy (SEM and TEM). The presence of randomly oriented and curved CNTs with an outer diameter of up to 64 nm was proved. The Ni/CeZrO2 particles were loosely covered with CNTs, freely dispersed over CNTs, and strongly attached to the external CNT walls. TEM proved the presence of a Ni/CeZrO2@CNT hybrid material that can be further used as catalyst, e.g., in WGS or DRM reactions. The impact of GHSV on hydrogen production during catalyst regeneration was determined. The catalyst was subjected to cyclic tests of CH4 decomposition and regeneration. According to the obtained results, Ni/CeZrO2 can be used in CH4 conversion to CNTs and H2 (instead of CH4 combustion), e.g., in the vicinity of installations that require methane utilization. Full article
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32 pages, 3642 KiB  
Review
Transition Metal–Nitrogen–Carbon (M–N–C) Catalysts for Oxygen Reduction Reaction. Insights on Synthesis and Performance in Polymer Electrolyte Fuel Cells
by Luigi Osmieri
ChemEngineering 2019, 3(1), 16; https://doi.org/10.3390/chemengineering3010016 - 11 Feb 2019
Cited by 78 | Viewed by 11080
Abstract
Platinum group metal (PGM)-free catalysts for oxygen reduction reaction (ORR) have attracted increasing interest as potential candidates to replace Pt, in the view of a future widespread commercialization of polymer electrolyte fuel cell (PEFC) devices, especially for automotive applications. Among different types of [...] Read more.
Platinum group metal (PGM)-free catalysts for oxygen reduction reaction (ORR) have attracted increasing interest as potential candidates to replace Pt, in the view of a future widespread commercialization of polymer electrolyte fuel cell (PEFC) devices, especially for automotive applications. Among different types of PGM-free catalysts, M–N–C materials appear to be the most promising ones in terms of activity. These catalysts can be produced using a wide variety of precursors containing C, N, and one (or more) active transition metal (mostly Fe or Co). The catalysts synthesis methods can be very different, even though they usually involve at least one pyrolysis step. In this review, five different synthesis methods are proposed, and described in detail. Several catalysts, produced approximately in the last decade, were analyzed in terms of performance in rotating disc electrode (RDE), and in H2/O2 or H2/air PEFC. The catalysts are subdivided in five different categories corresponding to the five synthesis methods described, and the RDE and PEFC performance is put in relation with the synthesis method. Full article
(This article belongs to the Special Issue Functional Materials for Renewable Energy Technologies)
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10 pages, 2568 KiB  
Article
Electrochemical Carbon Dioxide Reduction in Methanol at Cu and Cu2O-Deposited Carbon Black Electrodes
by Naoki Uemoto, Mai Furukawa, Ikki Tateishi, Hideyuki Katsumata and Satoshi Kaneco
ChemEngineering 2019, 3(1), 15; https://doi.org/10.3390/chemengineering3010015 - 8 Feb 2019
Cited by 13 | Viewed by 7119
Abstract
The electrochemical reduction of carbon dioxide in methanol was investigated with Cu and Cu2O-supported carbon black (Vulcan XC-72) nanoparticle electrodes. Herein, Cu or a Cu2O-deposited carbon black catalyst has been synthesized by the reduction method for a Cu ion, [...] Read more.
The electrochemical reduction of carbon dioxide in methanol was investigated with Cu and Cu2O-supported carbon black (Vulcan XC-72) nanoparticle electrodes. Herein, Cu or a Cu2O-deposited carbon black catalyst has been synthesized by the reduction method for a Cu ion, and the drop-casting method was applied for the fabrication of a modified carbon black electrode. A catalyst ink solution was fabricated by dispersing the catalyst particles, and the catalyst ink was added onto the carbon plate. The pH of suspension was effective for controlling the Cu species for the metallic copper and the Cu2O species deposited on the carbon black. Without the deposition of Cu, only CO and methyl formate were produced in the electrochemical CO2 reduction, and the production of hydrocarbons could be scarcely observed. In contrast, hydrocarbons were formed by using Cu or Cu2O-deposited carbon black electrodes. The maximum Faraday efficiency of hydrocarbons was 40.3% (26.9% of methane and 13.4% of ethylene) at −1.9 V on the Cu2O-deposited carbon black catalyst. On the contrary, hydrogen evolution could be depressed to 34.7% under the condition. Full article
(This article belongs to the Special Issue Carbon-Based Materials and Their Electrochemical Applications)
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12 pages, 4451 KiB  
Article
Solar Energy Assisted Membrane Reactor for Hydrogen Production
by Barbara Morico, Annarita Salladini, Emma Palo and Gaetano Iaquaniello
ChemEngineering 2019, 3(1), 9; https://doi.org/10.3390/chemengineering3010009 - 15 Jan 2019
Cited by 8 | Viewed by 4145
Abstract
Pd-based membrane reactors are strongly recognized as an effective way to boost H2 yield and natural gas (NG) conversion at low temperatures, compared to conventional steam reforming plants for hydrogen production, thereby representing a potential solution to reduce the energy penalty of such [...] Read more.
Pd-based membrane reactors are strongly recognized as an effective way to boost H2 yield and natural gas (NG) conversion at low temperatures, compared to conventional steam reforming plants for hydrogen production, thereby representing a potential solution to reduce the energy penalty of such a process, while keeping the lower CO2 emissions. On the other hand, the exploitation of solar energy coupled with a membrane steam reformer can further reduce the environmental impact of these systems. On this basis, the paper deals with the design activities and experimentation carried out at a pilot level in an integrated prototype where structured catalysts and Pd-based membranes are arranged together and thermally supported by solar-heated molten salts for steam reforming reaction Full article
(This article belongs to the Special Issue Membrane and Membrane Reactors Operations in Chemical Engineering)
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17 pages, 14077 KiB  
Review
Progress in Modeling of Silica-Based Membranes and Membrane Reactors for Hydrogen Production and Purification
by Kamran Ghasemzadeh, Angelo Basile and Adolfo Iulianelli
ChemEngineering 2019, 3(1), 2; https://doi.org/10.3390/chemengineering3010002 - 1 Jan 2019
Cited by 16 | Viewed by 4470
Abstract
Hydrogen is seen as the new energy carrier for sustainable energy systems of the future. Meanwhile, proton exchange membrane fuel cell (PEMFC) stacks are considered the most promising alternative to the internal combustion engines for a number of transportation applications. Nevertheless, PEMFCs need [...] Read more.
Hydrogen is seen as the new energy carrier for sustainable energy systems of the future. Meanwhile, proton exchange membrane fuel cell (PEMFC) stacks are considered the most promising alternative to the internal combustion engines for a number of transportation applications. Nevertheless, PEMFCs need high-grade hydrogen, which is difficultly stored and transported. To solve these issues, generating hydrogen using membrane reactor (MR) systems has gained great attention. In recent years, the role of silica membranes and MRs for hydrogen production and separation attracted particular interest, and a consistent literature is addressed in this field. Although most of the scientific publications focus on silica MRs from an experimental point of view, this review describes the progress done in the last two decades in terms of the theoretical approach to simulate silica MR performances in the field of hydrogen generation. Furthermore, future trends and current challenges about silica membrane and MR applications are also discussed. Full article
(This article belongs to the Special Issue Control and Optimization of Chemical and Biochemical Processes)
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80 pages, 39786 KiB  
Article
Two-Phase Bubble Columns: A Comprehensive Review
by Giorgio Besagni, Fabio Inzoli and Thomas Ziegenhein
ChemEngineering 2018, 2(2), 13; https://doi.org/10.3390/chemengineering2020013 - 27 Mar 2018
Cited by 120 | Viewed by 21196
Abstract
We present a comprehensive literature review on the two-phase bubble column; in this review we deeply analyze the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer phenomena. First, we discuss the flow regimes, the [...] Read more.
We present a comprehensive literature review on the two-phase bubble column; in this review we deeply analyze the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer phenomena. First, we discuss the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer. We also discuss how the operating parameters (i.e., pressure, temperature, and gas and liquid flow rates), the operating modes (i.e., the co-current, the counter-current and the batch modes), the liquid and gas phase properties, and the design parameters (i.e., gas sparger design, column diameter and aspect ratio) influence the flow regime transitions and the fluid dynamics parameters. Secondly, we present the experimental techniques for studying the global and local fluid dynamic properties. Finally, we present the modeling approaches to study the global and local bubble column fluid dynamics, and we outline the major issues to be solved in future studies. Full article
(This article belongs to the Special Issue Bubble Column Fluid Dynamics)
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23 pages, 3278 KiB  
Review
Recent Advances in Supported Metal Catalysts for Syngas Production from Methane
by Mohanned Mohamedali, Amr Henni and Hussameldin Ibrahim
ChemEngineering 2018, 2(1), 9; https://doi.org/10.3390/chemengineering2010009 - 7 Mar 2018
Cited by 51 | Viewed by 7074
Abstract
Over the past few years, great attention is paid to syngas production processes from different resources especially from abundant sources, such as methane. This review of the literature is intended for syngas production from methane through the dry reforming (DRM) and the steam [...] Read more.
Over the past few years, great attention is paid to syngas production processes from different resources especially from abundant sources, such as methane. This review of the literature is intended for syngas production from methane through the dry reforming (DRM) and the steam reforming of methane (SRM). The catalyst development for DRM and SRM represents the key factor to realize a commercial application through the utilization of more efficient catalytic systems. Due to the enormous amount of published literature in this field, the current work is mainly dedicated to the most recent achievements in the metal-oxide catalyst development for DRM and SRM in the past five years. Ni-based supported catalysts are considered the most widely used catalysts for DRM and SRM, which are commercially available; hence, this review has focused on the recent advancements achieved in Ni catalysts with special focus on the various attempts to address the catalyst deactivation challenge in both DRM and SRM applications. Furthermore, other catalytic systems, including Co-based catalysts, noble metals (Pt, Rh, Ru, and Ir), and bimetallic systems have been included in this literature review to understand the observed improvements in the catalytic activities and coke suppression property of these catalysts. Full article
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