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ChemEngineering, Volume 7, Issue 2 (April 2023) – 24 articles

Cover Story (view full-size image): Particle transport is still an immense challenge in many processes today and affects both the operation and the consistency of the product quality, which is essential in the pharmaceutical industry, for example. Therefore, we developed a suspension correlation of particles in the crystallization process for a slug flow crystallizer in the field of small-scale continuous crystallization in this paper to predict and ensure a reproducible process and consistent product quality. For this purpose, already existing dimensionless numbers were evaluated and modified employing force balances in order to predict the particle behavior in the liquid compartments in the slug flow crystallizer under different operating conditions and particle shapes of the substance system l-alanine/water using L-glutamic acid as an impurity during crystallization. View this paper
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13 pages, 1731 KiB  
Article
Kinetic Study of Acid Hydrolysis of the Glucose Obtained from Banana Plant
by Mónica Abril-González, Angélica Vele-Salto and Verónica Pinos-Vélez
ChemEngineering 2023, 7(2), 39; https://doi.org/10.3390/chemengineering7020039 - 21 Apr 2023
Cited by 1 | Viewed by 2021
Abstract
The biomass of crops in rotation, such as that generated by the banana plant, is an interesting source of lignocellulose due to its composition and availability. This research aimed to compare the amount of glucose obtained from different parts of the banana plant [...] Read more.
The biomass of crops in rotation, such as that generated by the banana plant, is an interesting source of lignocellulose due to its composition and availability. This research aimed to compare the amount of glucose obtained from different parts of the banana plant (leaves, rachis, and pseudostem) by hydrolysis with sulfuric acid at 100 °C. This reaction was analyzed to determine the amount of water and reagents consumed versus the glucose obtained. The optimal time and acid concentration were studied between 0–30 min and 3–5% v/v, respectively. The best results were obtained with the pseudostem of 13.02 gL−1 of glucose in a reaction time of 20 min and an acid concentration of 5%. In addition, the kinetic study of hydrolysis was carried out. The adjustment to the Saeman model was R2 0.96, which represents a first-order reaction and kinetic constants K1 = 0.5 and K2 = 0.3 min−1. This study has shown that these residues can be used as raw materials to generate value-added products due to their high glucose content. Full article
(This article belongs to the Special Issue Catalytic Systems for Biomass Valorization)
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18 pages, 8531 KiB  
Article
Synthesis and Characteristics of Composite Material with a Plant-Based Filler
by Natalia Igorevna Cherkashina, Zoya Vladimirovna Pavlenko, Dar’ya Sergeyevna Matveenko, Semen Nikolayevich Domarev, Dar’ya Vasil’yevna Pushkarskaya and Dar’ya Aleksandrovna Ryzhikh
ChemEngineering 2023, 7(2), 38; https://doi.org/10.3390/chemengineering7020038 - 18 Apr 2023
Cited by 2 | Viewed by 1686
Abstract
The article presents the results of synthesis of polymeric composite material based on epoxy binder and plant-based filler. Pre-dried and powdered wheat straw was used as a plant-based filler. The wheat straw content in the composite varied from 10 to 50 wt.%. Thermal, [...] Read more.
The article presents the results of synthesis of polymeric composite material based on epoxy binder and plant-based filler. Pre-dried and powdered wheat straw was used as a plant-based filler. The wheat straw content in the composite varied from 10 to 50 wt.%. Thermal, mechanical, and surface properties of composites depending on the wheat straw content were researched. In addition, the samples were studied for resistance to corrosive environments. The hydrophobic–hydrophilic surface balance of composites was evaluated, and their free surface energy was studied. Introduction of wheat straw in small amounts (up to 30 wt.%) increases bending strength of polymer from 18.65 ± 1.12 MPa to 22.61 ± 0.91 MPa; when the content is more than 40 wt.%, reduction of strength is observed. Even with a wheat straw powder content of 50 wt.%, the bending strength is 11.52 ± 1.03 MPa, which corresponds to the strength of the construction material. The upper limit of working temperature for the epoxy binder is 306 °C, and for the composite with the wheat straw content of 30 wt.%—264 °C. The surface of the pure polymer shows a hydrophilic character. The average value of the water wetting contact angle of the pure epoxy sample is 84.96 ± 9.03°. The introduction of 30 wt.% of wheat straw powder filler transforms the surface into hydrophobic one (average value of water wetting contact angle is 96.69 ± 5.71°). The developed composites can be applied in furniture production including tabletops or panels for floors. Future research will focus on expanding the types of plant-based fillers for polymer composites. Full article
(This article belongs to the Collection Green and Environmentally Sustainable Chemical Processes)
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12 pages, 6061 KiB  
Article
One-Step Crystallization of Gahnite Glass-Ceramics in a Wide Thermal Gradient
by Georgiy Yu. Shakhgildyan, Roman O. Alekseev, Nikita V. Golubev, Vitaliy I. Savinkov, Andrey S. Naumov, Natalia N. Presnyakova and Vladimir N. Sigaev
ChemEngineering 2023, 7(2), 37; https://doi.org/10.3390/chemengineering7020037 - 18 Apr 2023
Cited by 3 | Viewed by 1656
Abstract
The glass crystallization regime plays a crucial role in the fabrication of glass ceramics: it affects both phase composition and microstructure, and thus the properties of the final product. In the search for new glass-ceramic materials, the development of a proper heat-treatment schedule [...] Read more.
The glass crystallization regime plays a crucial role in the fabrication of glass ceramics: it affects both phase composition and microstructure, and thus the properties of the final product. In the search for new glass-ceramic materials, the development of a proper heat-treatment schedule involves the utilization of numerous glass samples that need to be thermally treated and then investigated to determine the values of the target characteristics. In this study, we evaluated the effect of crystallization temperature on the glass structure, phase composition, and hardness of glass ceramics in the ZnO-MgO-Al2O3-SiO2 system containing TiO2 and ZrO2 as nucleators. To maximize the number of heat treatments, we performed polythermal crystallization of the glass in a wide temperature range with the help of a gradient furnace. Using X-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we showed the precipitation of gahnite nanocrystals as the main phase in the bulk of a single glass sample and observed a gradual change in its microstructure, transparency, and hardness. The dependence of Vickers hardness values on heat treatment temperature was found to follow a non-linear trend, revealing the optimal thermal range for glass crystallization. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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15 pages, 4382 KiB  
Article
Effect of Rigid Xanthan Gums (RXGs) on Flow and Pressure Drops to Improve Drag Reduction Rates in Horizontal Pipe Flow
by Bashar J. Kadhim, Omar S. Mahdy, Sajda S. Alsaedi, Hasan S. Majdi, Zainab Y. Shnain, Asawer A. Alwaiti and Adnan A. AbdulRazak
ChemEngineering 2023, 7(2), 36; https://doi.org/10.3390/chemengineering7020036 - 14 Apr 2023
Cited by 2 | Viewed by 1513
Abstract
Drag reduction in turbulent flow may be significantly reduced by adding tiny quantities of fiber, polymer, and surfactant particles to the liquid. Different drag-reduction agents have proven to be effective in enhancing the flowability of the liquid when added. This study investigated the [...] Read more.
Drag reduction in turbulent flow may be significantly reduced by adding tiny quantities of fiber, polymer, and surfactant particles to the liquid. Different drag-reduction agents have proven to be effective in enhancing the flowability of the liquid when added. This study investigated the potential of decreasing the drag, turbulent flow, and pressure drop in horizontal pipe flow by using a mixture of modified xanthan gums (XGs). Xanthan gums are an environmentally friendly natural polymer complex. They can be extracted from xanthan gum plants and utilized to formulate different concentrations of complexes. The flowability of the xanthan gum was experimentally investigated in a 1-m-long pipe by using addition concentrations of 300 to 950 ppm, an inner diameter of 0.254 inches, and four different flow rates. The results revealed that the pressure drop was reduced considerably with an increase in the concentration of the additives. The mixture (xanthan gums plus water) resulted a favorable reduction in the pressure, which reached 65% at a concentration of 950 ppm. The results of the computational fluid dynamic simulation using the COMSOL simulator showed a change in the fluid velocity profiles, which became more parabolic. This occurred because of an increase in the mean fluid velocity due to the addition of the drag-reducing polymers. Full article
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17 pages, 1511 KiB  
Article
Green Fractionation Approaches for the Integrated Upgrade of Corn Cobs
by João Fialho, Patrícia Moniz, Luís C. Duarte and Florbela Carvalheiro
ChemEngineering 2023, 7(2), 35; https://doi.org/10.3390/chemengineering7020035 - 12 Apr 2023
Viewed by 1334
Abstract
Corn cob is an abundant agricultural residue worldwide, with high potential and interesting composition, and its valorization still needs to be studied. Selectively fractionating its structural components (hemicellulose, cellulose, and lignin), value-added products can be produced, eliminating waste. In this work, integrated fractionation [...] Read more.
Corn cob is an abundant agricultural residue worldwide, with high potential and interesting composition, and its valorization still needs to be studied. Selectively fractionating its structural components (hemicellulose, cellulose, and lignin), value-added products can be produced, eliminating waste. In this work, integrated fractionation approaches were developed and evaluated. First, an organosolv process was optimized (ethanol:water, 50:50, w/w). Then, as a comparative method, alkaline delignification (using NaOH, 1–2%) was also studied. The organosolv process allowed a significant delignification of the material (79% delignification yield) and, at the same time, a liquid phase containing a relevant concentration (14.6 g/L) of xylooligosaccharides (XOS). The resulting solid fraction, rich in cellulose, showed an enzymatic digestibility of 90%. The alkaline process increased the delignification yield to 94%, producing a solid fraction with a cellulose enzymatic digestibility of 83%. The two later techniques were also used in a combined strategy of hydrothermal processing (autohydrolysis) followed by delignification. The first allowed the selective hydrolysis of hemicellulose to produce XOS-rich hydrolysates (26.8 g/L, 67.3 g/100 g initial xylan). The further delignification processes, alkaline or organosolv, led to global delignification yields of 76% and 93%, respectively. The solid residue, enriched in glucan (above 75% for both combined processes), also presented high enzymatic saccharification yields, 89% and 90%, respectively. The fractionation strategies proposed, and the results obtained are very promising, enabling the integrated upgrading of this material into a biorefinery framework. Full article
(This article belongs to the Special Issue Catalytic Systems for Biomass Valorization)
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20 pages, 3890 KiB  
Article
Prediction of Particle Suspension State for Various Particle Shapes Used in Slug Flow Crystallization
by Anne Cathrine Kufner, Nico Westkämper, Henrik Bettin and Kerstin Wohlgemuth
ChemEngineering 2023, 7(2), 34; https://doi.org/10.3390/chemengineering7020034 - 12 Apr 2023
Cited by 2 | Viewed by 1436
Abstract
Particle transport is still an immense challenge in many processes today and affects both the operation and the consistency of the product quality, which is essential in the pharmaceutical industry, for example. Therefore, we developed a suspension correlation of particles in the crystallization [...] Read more.
Particle transport is still an immense challenge in many processes today and affects both the operation and the consistency of the product quality, which is essential in the pharmaceutical industry, for example. Therefore, we developed a suspension correlation of particles in the crystallization process for a slug flow crystallizer in the field of small-scale continuous crystallization in this paper to predict and ensure a reproducible process and consistent product quality. Furthermore, the developed suspension correlation shall provide the possibility to perform mechanistic modeling of the agglomeration behavior depending on the operating parameters in the crystallization process. For this purpose, already existing dimensionless numbers were evaluated and modified employing force balances in order to predict the particle behavior in the liquid compartments in the slug flow crystallizer under different operating conditions and particle shapes of the substance system l-alanine/water using L-glutamic acid as impurity during crystallization. Full article
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17 pages, 10147 KiB  
Article
Evaluating Electrochemical Properties of Layered NaxMn0.5Co0.5O2 Obtained at Different Calcined Temperatures
by Le Minh Nguyen, Van Hoang Nguyen, Doan My Ngoc Nguyen, Minh Kha Le, Van Man Tran and My Loan Phung Le
ChemEngineering 2023, 7(2), 33; https://doi.org/10.3390/chemengineering7020033 - 10 Apr 2023
Viewed by 1442
Abstract
P-type layered oxides recently became promising candidates for Sodium-ion batteries (NIBs) for their high specific capacity and rate capability. This work elucidated the structure and electrochemical performance of the layered cathode material NaxMn0.5Co0.5O2 (NMC) with x~1 [...] Read more.
P-type layered oxides recently became promising candidates for Sodium-ion batteries (NIBs) for their high specific capacity and rate capability. This work elucidated the structure and electrochemical performance of the layered cathode material NaxMn0.5Co0.5O2 (NMC) with x~1 calcined at 650, 800 and 900 °C. XRD diffraction indicated that the NMC material possessed a phase transition from P3- to P2-type layered structure with bi-phasic P3/P2 at medium temperature. The sodium storage behavior of different phases was evaluated. The results showed that the increased temperature improved the specific capacity and cycling stability. P2-NMC exhibited the highest initial capacity of 156.9 mAh·g−1 with capacity retention of 76.2% after 100 cycles, which was superior to the initial discharge capacity of only 149.3 mAh·g−1 and severe capacity fading per cycle of P3-NMC, indicating high robust structure stability by applying higher calcination temperature. The less stable structure also contributed to the fast degradation of the P3 phase at high current density. Thus, the high temperature P2 phase was still the best in sodium storage performance. Additionally, the sodium diffusion coefficient was calculated by cyclic voltammetry (CV) and demonstrated that the synergic effect of the two phases facile the sodium ion migration. Hard carbon||P2-NMC delivered a capacity of 80.9 mAh·g−1 and 63.3% capacity retention after 25 cycles. Full article
(This article belongs to the Topic Chemical and Biochemical Processes for Energy Sources)
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11 pages, 2110 KiB  
Article
Effect of a Tetraethoxysilane Hydrolysis Reaction Catalyst on the Precipitation of Hydrolysis Products in the Pores of a Polyimide Track Membrane
by Natalia Igorevna Cherkashina, Vyacheslav Ivanovich Pavlenko, Semen Nikolayevich Domarev and Nikolay Valeriyevich Kashibadze
ChemEngineering 2023, 7(2), 32; https://doi.org/10.3390/chemengineering7020032 - 10 Apr 2023
Viewed by 1645
Abstract
This paper presents the results of obtaining a composite film based on polyimide track membranes filled with a silica filler, although the issue of the deposition of this filler in the pores of the given membranes remained unexplored. The filler was obtained by [...] Read more.
This paper presents the results of obtaining a composite film based on polyimide track membranes filled with a silica filler, although the issue of the deposition of this filler in the pores of the given membranes remained unexplored. The filler was obtained by hydrolysis of tetraethoxysilane using an alkaline and acid catalyst. This paper presents the results of the effect of the tetraethoxysilane hydrolysis reaction catalyst on the precipitation of hydrolysis products in the pores of the polyimide track membrane. The factors influencing the formation of silicon oxide nanofibers within the matrix template (polyimide track membrane) are determined. It was found that the use of an acid catalyst provides the highest rates of filling, while when using an alkaline catalyst, the filling is practically not observed, and only single pores are filled. The properties of the composite film obtained were investigated. SEM images of the surface and chip of the composite while using alkaline and acid catalyst are presented. The spatial structure of composite films based on track membranes was investigated by FTIR spectroscopy. The hydrolysis of tetraethoxysilane in an acid medium significantly decreases the optical density index of the membranes and simultaneously increases their light transmission index. The greatest changes are observed in the range of 500–1000 nm, and there are no detectable changes in the range of 340–500 nm. When using an alkaline catalyst, there is not the same significant decrease in the relative optical density index D. Full article
(This article belongs to the Collection Green and Environmentally Sustainable Chemical Processes)
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39 pages, 9794 KiB  
Article
Effective Adsorptive Removal of Coomassie Violet Dye from Aqueous Solutions Using Green Synthesized Zinc Hydroxide Nanoparticles Prepared from Calotropis gigantea Leaf Extract
by Vairavel Parimelazhagan, Kannan Natarajan, Srinath Shanbhag, Sumanth Madivada and Harish S. Kumar
ChemEngineering 2023, 7(2), 31; https://doi.org/10.3390/chemengineering7020031 - 06 Apr 2023
Cited by 7 | Viewed by 2484
Abstract
The removal of color from dye wastewater is crucial, since dyes are extremely toxic and can cause cancer in a variety of life forms. Studies must be done to use cost-effective adsorbents for the removal of color from dye effluents to protect the [...] Read more.
The removal of color from dye wastewater is crucial, since dyes are extremely toxic and can cause cancer in a variety of life forms. Studies must be done to use cost-effective adsorbents for the removal of color from dye effluents to protect the environment. To our knowledge, virtually no research has been done to describe the possibility of using Calotropis gigantea leaf extract zinc hydroxide nanoparticles (CG-Zn(OH)2NPs) as an adsorbent for the decolorization of Coomassie violet (CV) from the aqueous emulsion, either in batch mode or continuously. In the present batch investigation, CV dye is removed from the synthetic aqueous phase using CG-Zn(OH)2NPs as an adsorbent. The synthesized nanoparticles were characterized using various instrumental techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and Brunauer–Emmett–Teller (BET) surface area and pore volume, a particle size analyser, and zero-point charge. The decolorization efficacy of CV dye from an aqueous phase by the adsorbent was examined in batch mode by varying process parameters. The consequences of various experimental variables were optimized using response surface methodology (RSM) to achieve the maximum decolorization efficiency (90.74%) and equilibrium dye uptake, qe (35.12 mg g−1). The optimum pH, dye concentration, CG-Zn(OH)2NPs adsorbent dosage, and particle size were found to be 1.8, 225 mg L−1, 5 g L−1, and 78 μm, respectively for CV dye adsorption capacity at equilibrium. The adsorbent zero-point charge was found to be at pH 8.5. The Langmuir isotherm model provided a good representation of the equilibrium data in aqueous solutions, with a maximum monolayer adsorption capability (qmax) of 40.25 mg g−1 at 299 K. The dye adsorption rate follows a pseudo-second-order kinetic model at various dye concentrations, which indicated that the reaction is more chemisorption than physisorption. The negative values of ΔG and positive values of ΔH at different temperatures indicate that the adsorption process is spontaneous and endothermic, respectively. Reusability tests revealed that the prepared nanoparticles may be used for up to three runs, indicating that the novel CG-Zn(OH)2NPs seems to be a very promising adsorbent for the removal of Coomassie violet dye from wastewater. Full article
(This article belongs to the Collection Green and Environmentally Sustainable Chemical Processes)
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19 pages, 5884 KiB  
Article
Method for Intensive Gas–Liquid Dispersion in a Stirred Tank
by Nikolai A. Voinov, Alexander S. Frolov, Anastasiya V. Bogatkova, Denis A. Zemtsov and Olga P. Zhukova
ChemEngineering 2023, 7(2), 30; https://doi.org/10.3390/chemengineering7020030 - 04 Apr 2023
Viewed by 1335
Abstract
This article presents the results of hydrodynamics and mass exchange in a stirred tank upon the introduction of gas from an open gas vortex cavity into local liquid regions with reduced pressure. It establishes conditions for the intensive dispersion of gas. Velocity fields [...] Read more.
This article presents the results of hydrodynamics and mass exchange in a stirred tank upon the introduction of gas from an open gas vortex cavity into local liquid regions with reduced pressure. It establishes conditions for the intensive dispersion of gas. Velocity fields and liquid pressure behind the stirrer paddles are determined by numerical simulation in OpenFOAM. The gas content value, gas bubble diameters, and phase surface are determined experimentally. The stirrer power criterion is calculated by taking into account the gas content and power input. The experimental mass transfer data based on the absorption of atmospheric oxygen into water during the dispersion of gas from the open vortex cavity in the local liquid regions behind the rotating stirrer paddles are presented. In this case, the energy dissipation from the rotating stirrer reaches 25 W/kg, with a phase surface of 1000 m−1 and a surface mass transfer coefficient of up to 0.3·10−3 m/s. These parameters are obviously higher than the data obtained in the apparatus for mass exchange through surface vorticity. The advantage of the given method for gas dispersion in a liquid is the functional stability of the apparatus regardless of how deep the stirrer is immersed in the liquid or the temperature or pressure of the gas. Apparatuses based on the intensive gas dispersion method allow for varying the mass transfer coefficient and gas content across a broad range of values. This allows establishing a dependency between the experimentally obtained mass transfer coefficient, energy dissipation, and phase surface values. An equation for calculating the mass transfer coefficient is formulated by taking into account the geometric parameters of the stirrer apparatus based on the stirring power and phase surface values. Full article
(This article belongs to the Special Issue Process Intensification for Chemical Engineering and Processing)
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12 pages, 1868 KiB  
Article
Preparation and Spectroscopic Characterization of Ternary Inclusion Complexes of Ascorbyl Palmitate and Urea with γ-Cyclodextrin
by Yutaka Inoue, Ayumi Nanri, Florencio Jr. Arce, Gerard Lee See, Takashi Tanikawa, Takami Yokogawa and Masashi Kitamura
ChemEngineering 2023, 7(2), 29; https://doi.org/10.3390/chemengineering7020029 - 29 Mar 2023
Cited by 1 | Viewed by 1272
Abstract
A three-component inclusion complex of ascorbyl palmitate (ASCP), urea (UR), and γ-cyclodextrin (γCD) with a molar ratio of 1/12 has been prepared for the first time using the evaporation method (EVP method) and the grinding and mixing method (GM method). Also, we investigated [...] Read more.
A three-component inclusion complex of ascorbyl palmitate (ASCP), urea (UR), and γ-cyclodextrin (γCD) with a molar ratio of 1/12 has been prepared for the first time using the evaporation method (EVP method) and the grinding and mixing method (GM method). Also, we investigated changes in the physicochemical properties of the three-component complexes. The powder X-ray diffraction (PXRD) measurements showed ASCP, UR, and γCD characteristic peaks in the physical mixture (PM) (AU (ASCP/UR = 1/12)/γCD = 1/2). In GM (AU (ASCP/UR = 1/12)/γCD = 1/1), new diffraction peaks were observed around 2θ = 7.5° and 16.6°, while characteristic peaks derived from EVP (ASCP/UR = 1/12) were observed at 2θ = 23.4° and 24.9°. On the other hand, new diffraction peaks at 2θ = 7.4° and 16.6° were observed in GM (1/2). In the differential scanning calorimeter (DSC) measurement, an endothermic peak at around 83 °C was observed in the GM (1/1) sample, which is thought to originate from the phase transition of urea from the hexagonal to the tetragonal form. An endothermic peak around 113.9 °C was also observed for EVP (ASCP/UR = 1/12). However, no characteristic phase transition-derived peak or EVP (ASCP/UR = 1/12)-derived endothermic peak was observed in GM (1/2). Near infrared (NIR) spectroscopy of GM (1/2) showed no shift in the peak derived from the CH group of ASCP. The peaks derived from the NH group of UR shifted to the high and low wavenumber sides at 5032 cm−1 and 5108 cm−1 in EVP (ASCP/UR = 1/12). The peak derived from the OH group of γCD shifted, and the peak derived from the OH group of ASCP broadened at GM (1/2). These results suggest that AU (ASCP/UR = 1/12)/γCD prepared by the mixed grinding method formed inclusion complexes at the molar ratio (1/2). Full article
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10 pages, 1499 KiB  
Communication
Production of Anhydrite Binder from Waste Fluorangydrite
by Lyaila Bayatanova, Bauyrzhan Rakhadilov, Aidar Kengesbekov, Manarbek Kylyshkanov, Saule Abdulina, Meruyert Adilkanova and Zhuldyz Sagdoldina
ChemEngineering 2023, 7(2), 28; https://doi.org/10.3390/chemengineering7020028 - 27 Mar 2023
Viewed by 1160
Abstract
The technology for obtaining hydrofluoric acid and the peculiarities of its production were studied, and the physical and chemical properties of the waste were examined. Activators that accelerated the hardening of the anhydrite binder were selected. The process of recycling fluorine hydrite waste [...] Read more.
The technology for obtaining hydrofluoric acid and the peculiarities of its production were studied, and the physical and chemical properties of the waste were examined. Activators that accelerated the hardening of the anhydrite binder were selected. The process of recycling fluorine hydrite waste from the production of hydrofluoric acid at Ulba Metallurgical Plant JSC was studied, and anhydrite unburnt binder with a setting time of 30 min was obtained. On the basis of the obtained data, a technological scheme of anhydrite binder production was developed. The effectiveness of the technological scheme was confirmed experimentally. This work aimed to study the possibility of the integrated use of secondary and anthropogenic raw materials from Ulba Metallurgical Plant, which represents an important means of not only increasing production efficiency and economic benefits and reducing the irrational alienation of land resources, but also protecting against the pollution of water and air basins, as the environmental policy of UMP JSC is nowadays of great importance. Full article
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16 pages, 3937 KiB  
Article
Heterogeneous Photodegradation Reaction of Phenol Promoted by TiO2: A Kinetic Study
by Francesco Broccoli, Rosanna Paparo, Maria Rosaria Iesce, Martino Di Serio and Vincenzo Russo
ChemEngineering 2023, 7(2), 27; https://doi.org/10.3390/chemengineering7020027 - 24 Mar 2023
Cited by 2 | Viewed by 1509
Abstract
Phenol is widely used in industry. Due to its high stability and toxicity, it represents a threat to the environment and human health. In this study, a kinetic investigation of phenol heterogeneous photodegradation was conducted using commercial Aeroxide P-25, performing experiments in a [...] Read more.
Phenol is widely used in industry. Due to its high stability and toxicity, it represents a threat to the environment and human health. In this study, a kinetic investigation of phenol heterogeneous photodegradation was conducted using commercial Aeroxide P-25, performing experiments in a wide range of conditions. In detail, a negligible adsorption effect was detected. An activation energy of Ea = 14.3 ± 0.5 kJ mol−1 was measured, and the catalyst loading effect indicated an optimal condition due to the shield of the catalyst particles to the UV irradiation. The catalyst was most active at pH = 7 and it was stable for 25 h of reaction time; thus, it will be worth to investigate its application in flow. Full article
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14 pages, 4111 KiB  
Article
The Performance of Microfiltration Using Hydrophilic and Hydrophobic Membranes for Phenol Extraction from a Water Solution
by Tamara Kawther Hussein, Nidaa Adil Jasim and Abdul-Sahib T. Al-Madhhachi
ChemEngineering 2023, 7(2), 26; https://doi.org/10.3390/chemengineering7020026 - 24 Mar 2023
Cited by 1 | Viewed by 1622
Abstract
Two types of membranes, for hydrophilic and hydrophobic microfiltration, were prepared as flat sheets to treat a phenol-contaminated water solution. The membranes were fabricated using four synthetic polymers: polysulfone, polyethylene oxide, dimethylacetamide, and N-methyl-2-pyrrolidone. Scanning electron microscope measurements of the top-surface and cross-section [...] Read more.
Two types of membranes, for hydrophilic and hydrophobic microfiltration, were prepared as flat sheets to treat a phenol-contaminated water solution. The membranes were fabricated using four synthetic polymers: polysulfone, polyethylene oxide, dimethylacetamide, and N-methyl-2-pyrrolidone. Scanning electron microscope measurements of the top-surface and cross-section images of the produced membranes were used to characterize them physically. Distilled water and water contaminated with phenol were used to evaluate the membrane’s performance based on the flux results depending on pressure, the concentration of phenol, and temperature variables. Meanwhile, the rejection performance was evaluated using the phenol-contaminated water solution. The results show that the flux increased with increases in pressure and temperature and decreased with increases in phenol concentration. Distilled water gave far higher results than water contaminated with phenol. The flux of distilled water ranged from 52.18 to 73.15 L/m2/h for the hydrophilic type and from 72.27 to 97.46 L/m2/h for the hydrophobic type, whereas the flux of water contaminated with phenol solution ranged from 26.58 to 61.55 L/m2/h for the hydrophilic type and from 29.98 to 80.55 L/m2/h for the hydrophobic type. Meanwhile, the phenol solution’s rejection was 60% when using a hydrophilic membrane, whereas it was only 45% when a hydrophobic membrane was used. The hydrophobic membrane showed high fluxes and low rejection. Thus, transport through this membrane is closer to having viscous behavior than that through the hydrophilic membrane; in contrast, the permeability through the hydrophilic membrane is less because the pore size decreases the viscous flow mechanism. Full article
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17 pages, 769 KiB  
Article
Correlating Pure Component Properties with MOSCED Solubility Parameters: Enthalpy of Vaporization and Vapor Pressure
by Nick H. Wong, Pratik Dhakal, Sydnee N. Roese and Andrew S. Paluch
ChemEngineering 2023, 7(2), 25; https://doi.org/10.3390/chemengineering7020025 - 18 Mar 2023
Viewed by 1569
Abstract
Tools to predict vapor–liquid phase equilibria are indispensable for the conceptualization and design of separation processes. Modified separation of cohesive energy density (MOSCED) is a solubility-parameter-based method parameterized to make accurate predictions of the limiting activity coefficient. As a solubility-parameter-based method, MOSCED can [...] Read more.
Tools to predict vapor–liquid phase equilibria are indispensable for the conceptualization and design of separation processes. Modified separation of cohesive energy density (MOSCED) is a solubility-parameter-based method parameterized to make accurate predictions of the limiting activity coefficient. As a solubility-parameter-based method, MOSCED can not only make quantitative predictions, but can shed light on the underlying intermolecular interactions. In the present study, we demonstrated the ability of MOSCED to correlate the enthalpy of vaporization and vapor pressure at a specific temperature using multiple linear regression. With this addition, MOSCED is able to predict vapor–liquid phase equilibria in the absence of reference data. This was demonstrated for the prediction of the Henry’s constant and solvation free energy of organic solutes in water, which was found to be superior to mod-UNIFAC. In addition to being able to make phase equilibrium predictions, the ability to correlate the enthalpy of vaporization and vapor pressure offers the opportunity to include additional properties in the regression of the MOSCED parameters. Given this success, we additionally attempted to correlate a wide range of physical properties using a similar expression. While, in some cases, the results were reasonable, they were inferior to the correlations of the enthalpy of vaporization and vapor pressure. Future efforts will be needed to improve the correlations. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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12 pages, 2035 KiB  
Article
Dibasic Magnesium Hypochlorite as an Oxidant to Tune Pasting Properties of Potato Starch in One Step
by J. O. P. Broekman, Brian W. Dijkhuis, Johanna A. Thomann, André Heeres, Hero J. Heeres and Peter J. Deuss
ChemEngineering 2023, 7(2), 24; https://doi.org/10.3390/chemengineering7020024 - 14 Mar 2023
Viewed by 1494
Abstract
Modified starches are used widely in the food industry but often have a low nutritional value, lacking minerals vital for the human body, such as magnesium. Magnesium addition to native starches has been shown to result in changes in pasting properties. However, little [...] Read more.
Modified starches are used widely in the food industry but often have a low nutritional value, lacking minerals vital for the human body, such as magnesium. Magnesium addition to native starches has been shown to result in changes in pasting properties. However, little work has been done on the addition of magnesium and other divalent cations to highly oxidised starches. In this work, we used dibasic magnesium hypochlorite (DMH) to oxidise potato starch to an industrially relevant degree of oxidation while at the same time introducing magnesium into the starch structure. We found that magnesium incorporation changes the pasting properties of starch and increases the gelatinisation temperature significantly, possibly due to an ionic cross-linking effect. These properties resemble the properties found for heat-moisture-treated potato starches. This change in properties was found to be reversible by performing a straightforward exchange of metal cations, either from sodium to magnesium or from magnesium to sodium. We show in this work the potential of the addition of divalent cations to highly oxidised starches in modifying the rheological and pasting properties of these starches and at the same time adding possible health benefits to modified starches by introducing magnesium. Full article
(This article belongs to the Special Issue Catalytic Systems for Biomass Valorization)
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17 pages, 4349 KiB  
Article
Ti/Zr/O Mixed Oxides for the Catalytic Transfer Hydrogenation of Furfural to GVL in a Liquid-Phase Continuous-Flow Reactor
by Anna Saotta, Alessandro Allegri, Francesca Liuzzi, Giuseppe Fornasari, Nikolaos Dimitratos and Stefania Albonetti
ChemEngineering 2023, 7(2), 23; https://doi.org/10.3390/chemengineering7020023 - 14 Mar 2023
Cited by 1 | Viewed by 1701
Abstract
This work aims to develop an efficient catalyst for the cascade reaction from furfural to γ-valerolactone in a liquid-phase continuous reactor. This process requires both Lewis and Brønsted acidity; hence, a bifunctional catalyst is necessary to complete the one-pot reaction. Ti/Zr/O mixed oxide-based [...] Read more.
This work aims to develop an efficient catalyst for the cascade reaction from furfural to γ-valerolactone in a liquid-phase continuous reactor. This process requires both Lewis and Brønsted acidity; hence, a bifunctional catalyst is necessary to complete the one-pot reaction. Ti/Zr/O mixed oxide-based catalysts were chosen to this end as balancing metal oxide composition allows the acidity characteristics of the overall material to be modulated. Oxides with different compositions were then synthesized using the co-precipitation method. After characterization via porosimetry and NH3-TPD, the catalyst with equimolar quantities of the two components was demonstrated to be the best one in terms of superficial area (279 m2/g) and acid site density (0.67 mmol/g). The synthesized materials were then tested using a plug flow reactor at 180 °C, with a 10 min contact time. Ti/Zr/O (1:1) was demonstrated to be the most promising catalyst during the recycling tests as it allowed obtaining the highest selectivities in the desired products (about 45% in furfuryl isopropyl ether and 20% in γ-valerolactone) contemporaneously with 100% furfural conversion. Full article
(This article belongs to the Special Issue Catalytic Systems for Biomass Valorization)
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10 pages, 2840 KiB  
Article
Photocatalytic and Glucose Sensing Properties of ZnO-Based Nanocoating
by Dina Bakranova, Bekbolat Seitov and Nurlan Bakranov
ChemEngineering 2023, 7(2), 22; https://doi.org/10.3390/chemengineering7020022 - 09 Mar 2023
Cited by 3 | Viewed by 1461
Abstract
Here, we report a simple and versatile synthesis of low-dimensional ZnO nanosheet (NS) arrays modified with Fe2O3 (hematite) to assemble photocatalytic coatings and non-enzymatic glucose sensors. Photocatalytic coatings made of widespread elements (zinc and iron) were tested for methylene blue [...] Read more.
Here, we report a simple and versatile synthesis of low-dimensional ZnO nanosheet (NS) arrays modified with Fe2O3 (hematite) to assemble photocatalytic coatings and non-enzymatic glucose sensors. Photocatalytic coatings made of widespread elements (zinc and iron) were tested for methylene blue (MB) dye decolorization under ultraviolet and visible (UV-vis) irradiation. A comparative study of unmodified and modified ZnO NS photocatalysts revealed a significant decrease in the dye concentration in 180 min when ZnO/Fe2O3 arrays were used. Size dependence efficiency of the hematite layer deposited onto ZnO is presented. A study of the sensitivity of biosensors made of ZnO nanostructures and ZnO/Fe2O3 nanocomposites for glucose detection showed an improvement in sensitivity with increased Fe2O3 thickness. The structure and morphology of low-dimensional coatings were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). The optical properties of nanoarrays showed a red shift of absorption after modifying ZnO with hematite layers, which holds good promise for expanding photocatalytic activity in the visible region. Full article
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19 pages, 2331 KiB  
Article
Comparison of the Dynamic and Thermal Behavior of Different Ideal Flow Crystallizers
by László Balogh, Attila Egedy, Zsolt Ulbert and Ágnes Bárkányi
ChemEngineering 2023, 7(2), 21; https://doi.org/10.3390/chemengineering7020021 - 06 Mar 2023
Viewed by 1602
Abstract
In this simulation study, we compare the dynamics and thermal behavior of different ideal flow crystallizers. The first step in creating mathematical models for the crystallizers was the implementation of the population balance equation. The population balance equation was completed with mass balance [...] Read more.
In this simulation study, we compare the dynamics and thermal behavior of different ideal flow crystallizers. The first step in creating mathematical models for the crystallizers was the implementation of the population balance equation. The population balance equation was completed with mass balance equations for the solute and the solvent as well as in the case of non-isothermal crystallizers with an energy balance equation. The solution to the population balance equation, which is a partial differential equation, can only be performed numerically. Using the method of moments, which calculates the moments of the population density function, gives a mathematically simpler model for simulating and analyzing the crystallizers. All crystallizers studied are considered mixed suspension and mixed product crystallizers. In this simulation study, the investigated crystallizers are the batch mixed suspension and mixed product isothermal crystallizer, the batch mixed suspension and mixed product non-isothermal crystallizer, and the continuous mixed suspension and mixed product removal (CMSMPR) non-isothermal crystallizer equipped with a cooling jacket. We consider citric acid as the solid material to be crystallized, and a water–glycol system is used as a cooling medium. Considering the nucleation kinetics, we applied both primary and secondary nucleation. In the case of a crystal growth kinetic, we assumed a size-independent growth rate. The highest expected value and the variance of the crystal product occur in the isotherm batch case, which can be explained by the high crystallization rate caused by the high supersaturation. Contrary to this, in the non-isothermal batch case, the final mean particle size and variance are the lowest. In continuous mode, the variance and mean values are between the values obtained in the two other cases. In this case, the supersaturation is maintained at a constant level in the steady state, and the average residence time of the crystal particles also has an important influence on the crystal size distribution. In the case of non-isothermal crystallization, the simulation studies show that the application of the energy balance provides different dynamics for the crystallizers. The implementation of an energy balances into the mathematical model enables the calculation of the thermal behavior of the crystallizers, enabling the model to be used more widely. Full article
(This article belongs to the Special Issue Modeling of Chemical Kinetics and Reactor Design)
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12 pages, 7954 KiB  
Article
Graphite/β-PbO2 Composite Inert Anode Synthesis Using Electrochemical Methods
by Selpiana Selpiana, Sri Haryati and Muhammad Djoni Bustan
ChemEngineering 2023, 7(2), 20; https://doi.org/10.3390/chemengineering7020020 - 06 Mar 2023
Cited by 1 | Viewed by 1468
Abstract
The anode material is one of the determining factors for the success of the electrowinning process. This study aims to coat the graphite substrate with β-PbO2 to produce an inert graphite/β-PbO2 composite material with low cost and good quality. The graphite/β-PbO [...] Read more.
The anode material is one of the determining factors for the success of the electrowinning process. This study aims to coat the graphite substrate with β-PbO2 to produce an inert graphite/β-PbO2 composite material with low cost and good quality. The graphite/β-PbO2 synthesis is expected to be used as an anode for inert composites for electrowinning processes. The β-PbO2 deposition layer was prepared on the surface of the graphite substrate by an electrodeposition process using a sulfuric acid electrolyte. The effect of electrolyte concentration and voltage on graphite/β-PbO2 synthesis was investigated using a potentiodynamic polarization test through Tafel analysis. Experimental data have shown that there is an increase in the current density value at the beginning of the process and then a decrease due to passivation; this is due to anodic polarization in the graphite/β-PbO2 synthesis process. Suitable conditions can effectively increase the rate of formation of β-PbO2. The results of scanning electron microscopy with energy-dispersive X-ray spectroscopic analysis of the formed crystal structure showed that the β-PbO2 deposition layer obtained had a well-formed tetragonal structure at a voltage of 9 V. Full article
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16 pages, 569 KiB  
Article
Temperature Distribution and Thermal Criticality of Kinetics Exothermic Reactant in Concentric Cylinders Subject to Various Boundary Conditions
by Sulyman Olakunle Salawu and Samuel Segun Okoya
ChemEngineering 2023, 7(2), 19; https://doi.org/10.3390/chemengineering7020019 - 05 Mar 2023
Cited by 1 | Viewed by 991
Abstract
A study of the high-heat distribution of reacting species with approximation kinetics is essential in practical applications, for example, chemical synthesis, explosion safety and propulsion denotatives. As such, the temperature distribution and thermal criticality of an exothermic kinetics species in a concentric cylinder [...] Read more.
A study of the high-heat distribution of reacting species with approximation kinetics is essential in practical applications, for example, chemical synthesis, explosion safety and propulsion denotatives. As such, the temperature distribution and thermal criticality of an exothermic kinetics species in a concentric cylinder is the focus of this study. The chemistry of the pre-exponential factor, termination step, initiation rate and branch chain of the combustible reactant is investigated to study the system’s critical behaviour. The temperature is assumed not to be large; as such, the consumption of reactant species is ignored. A partition weighted residual semi-analytical approximate solution to heat propagation under boundary conditions, thermal ignition and branch chain for varying activation energies and chemical kinetics is discussed. The solution validation criteria for the approximate semi-analytical method and numerical method are established. This study ascertained the impact of boundary conditions on the explosion, and the effect of certain parameter changes on the heat distribution and thermal criticality was shown to be significant. Hence, the outcomes offer an understanding into the homogeneous species behaviour in a cylindrical geometry. Full article
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9 pages, 2540 KiB  
Article
Degradation Studies of Air-Exposed Black Phosphorous and Black Arsenic Phosphorous
by Usman O. Abu, Dinushika Vithanage, Ashan Vitharana, Jacek B. Jasinski and Gamini Sumanasekera
ChemEngineering 2023, 7(2), 18; https://doi.org/10.3390/chemengineering7020018 - 03 Mar 2023
Cited by 3 | Viewed by 1182
Abstract
This work investigates the effects of oxygen and humidity on black phosphorous (BP) and black arsenic phosphorous (AsxP1x ) flakes using Raman spectroscopy and in situ electric transport measurements (four-probe resistance and thermoelectric power, TEP). The results [...] Read more.
This work investigates the effects of oxygen and humidity on black phosphorous (BP) and black arsenic phosphorous (AsxP1x ) flakes using Raman spectroscopy and in situ electric transport measurements (four-probe resistance and thermoelectric power, TEP). The results show that the incorporation of arsenic into the lattice of BP renders it more stable, with the degradation times for BP, As0.2P0.8, and As0.4P0.6 being 4, 5, and 11 days, respectively. The P-P Raman peak intensities were determined to decrease with exposure to oxygen and moisture. The TEP measurements confirmed that both BP and AsxP1x are p-type semiconductors with the TEP of As0.4P0.6 stabilizing more slowly than that of BP. In addition, the four-probe resistance of BP and AsxP1x stabilized significantly faster when exposed to air after being degassed in a vacuum. This was attributed to the charge transfer between the oxygen redox potential of air and the Fermi energy (EF) of the semiconductors. Full article
(This article belongs to the Special Issue Feature Papers in Chemical Engineering)
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12 pages, 3618 KiB  
Article
Mechanical Degradation of Polyethylene Plastic Film by Oxo-Degradable Additives
by Noha Said Yousef
ChemEngineering 2023, 7(2), 17; https://doi.org/10.3390/chemengineering7020017 - 01 Mar 2023
Cited by 2 | Viewed by 1526
Abstract
Utilizing oxo-degradable additives is an alternate, efficient method of managing plastic trash. To prepare the polymer chain for microorganisms to break down the fragments over time, oxo-degradation of plastics involves breaking the chain into small pieces. In this study, a film with a [...] Read more.
Utilizing oxo-degradable additives is an alternate, efficient method of managing plastic trash. To prepare the polymer chain for microorganisms to break down the fragments over time, oxo-degradation of plastics involves breaking the chain into small pieces. In this study, a film with a thickness of 35 µm is created by mixing a mixture of linear low-density polyethylene (LLDPE) and d2w grade master batch (pro-oxidant). This thickness falls within the range of specifications for linear low-density polyethylene (LLDPE) films manufactured in petrochemical businesses. Additionally, is the study investigates how the mechanical characteristics of linear low-density polyethylene (LLDPE) are affected by the addition of a d2w pro-oxidant additive at five different weight percentages (0, 0.5, 1, 2, and 3% w/w). After thermal processing for films in an oven for one to seven days, the progress of LLDPE film is monitored by FTIR analysis to check for the presence of the carbonyl group by assessing the mechanical properties of the film. Tensile strength at break, tensile strength at yield, elongation at break, and elongation at yield are the mechanical qualities that are measured. Both the machine direction (MD) and the transverse direction (TD) are used to measure all properties. Following seven days of exposure to the oven at 70 °C, the mechanical properties of the film deteriorated. Both in the machine and transverse directions (MD and TD), the tensile strength at break dropped by 46.62% and 31.8%, respectively. Both in the machine and transverse directions (MD and TD), the tensile strength at yield dropped by 22% and 36.36%, respectively. Both machine and transverse elongation at break (MD and TD) were reduced by 21% and 38.36%, respectively. Following the addition of pro-oxidant and after thermo-oxidative treatment in an oven at 70 °C for 7 days, the results of the FTIR measurement for LLDPE did not significantly alter. Full article
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20 pages, 4291 KiB  
Article
Experimental Evaluation of a Coated Foam Catalytic Reactor for the Direct CO2-to-Methanol Synthesis Process
by Kyatsinge Cedric Musavuli, Nicolaas Engelbrecht, Raymond Cecil Everson, Phillimon Modisha, Gunther Kolb, Ralf Zapf, Christian Hofmann and Dmitri Bessarabov
ChemEngineering 2023, 7(2), 16; https://doi.org/10.3390/chemengineering7020016 - 21 Feb 2023
Viewed by 1778
Abstract
The era of considering carbon dioxide (CO2) as a waste stream has passed. New methods of utilising CO2 as a carbon feedstock are currently the focus of extensive research efforts. A fixed-bed reactor containing a commercial Cu/ZnO/Al2O3 [...] Read more.
The era of considering carbon dioxide (CO2) as a waste stream has passed. New methods of utilising CO2 as a carbon feedstock are currently the focus of extensive research efforts. A fixed-bed reactor containing a commercial Cu/ZnO/Al2O3 catalyst washcoated on a Cu foam was used for the synthesis of methanol through direct CO2 hydrogenation. Catalytic activity tests in this reactor were conducted at reaction pressures of 30 and 50 bar, temperatures in the range 190–250 °C, and weight hourly space velocities (WHSV) in the range 1.125–2.925 NL gcat−1 h−1. The best reactor performance was recorded at 50 bar pressure: CO2 conversion and methanol selectivity of 27.46% and 82.97%, respectively, were obtained at 240 °C and 1.125 NL gcat−1 h−1. Increasing the WHSV to 2.925 NL gcat−1 h−1 resulted in a twofold increase in methanol weight time yield (WTY) to 0.18 gMeOH gcat−1 h−1 and a decrease in methanol selectivity to 70.55%. The results presented in this investigation provide insight into the performance of a bench-scale reactor in which mass transfer limitations are non-negligible and demonstrate that metal foams are promising catalyst support structures for CO2 hydrogenation towards methanol production. Full article
(This article belongs to the Special Issue Recent Advances in Novel Chemical Reactor)
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