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3 pages, 220 KiB

Open AccessEditorial

A Themed Issue in Honor of Prof. Dr. Vicente Rives

by Miguel Angel Vicente, Raquel Trujillano and Francisco M. Labajos

ChemEngineering 2023, 7(6), 102; https://doi.org/10.3390/chemengineering7060102 - 31 Oct 2023

Viewed by 1731

Abstract

Professor Vicente Rives developed a very long and fruitful career as a teacher of Inorganic Chemistry and Materials Chemistry and has been a dedicated researcher in these and related fields [...] Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

Research

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17 pages, 5448 KiB

Open AccessArticle

Adsorption Properties and Hemolytic Activity of Porous Aluminosilicates in a Simulated Body Fluid

by Olga Yu. Golubeva, Yulia A. Alikina, Elena Yu. Brazovskaya and Nadezhda M. Vasilenko

ChemEngineering 2022, 6(5), 78; https://doi.org/10.3390/chemengineering6050078 - 6 Oct 2022

Cited by 7 | Viewed by 2747

Abstract

A study of the adsorption features of bovine serum albumin (BSA), sodium and potassium cations, and vitamin B1 by porous aluminosilicates with different structures in a medium simulating blood plasma was conducted. The objects of this study were synthetic silicates with a montmorillonite [...] Read more.

A study of the adsorption features of bovine serum albumin (BSA), sodium and potassium cations, and vitamin B1 by porous aluminosilicates with different structures in a medium simulating blood plasma was conducted. The objects of this study were synthetic silicates with a montmorillonite structure Na_2x(Al_2(1-x),Mg_2x)Si₄O₁₀(OH)₂·nH₂O (x = 0.5, 0.9, 1), aluminosilicates of the kaolinite subgroup Al₂Si₂O₅(OH)₄ with different particle morphologies (spherical, nanosponge, nanotubular, and platy), as well as framed silicates (Beta zeolite). An assessment of the possibility of using aluminosilicates as hemosorbents for extracorporeal blood purification was carried out. For this purpose, the sorption capacity of the samples both with respect to model medium molecular weight toxicants (BSA) and natural blood components—vitamins and alkaline cations—was investigated. The samples were also studied by X-ray diffraction, electron microscopy, and low-temperature nitrogen adsorption. The zeta potential of the sample’s surfaces and the distribution of active centers on their surfaces by the method of adsorption of acid-base indicators were determined. A hemolytic test was used to determine the ability of the studied samples to damage the membranes of eukaryotic cells. Langmuir, Freundlich, and Temkin models were used to describe the experimental BSA adsorption isotherms. To process the kinetic data, pseudo-first-order and pseudo-second-order adsorption models were used. It was found that porous aluminosilicates have a high sorption capacity for medium molecular weight pathogens (up to 12 times that of activated charcoal for some samples) and low toxicity to blood cells. Based on the obtained results, conclusions were made about the prospects for the development of new selective non-toxic hemosorbents based on synthetic aluminosilicates with a given set of properties. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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13 pages, 3132 KiB

Open AccessArticle

The Inhibitive Effect of Sebacate-Modified LDH on Concrete Steel Reinforcement Corrosion

by David Caballero, Ruben Beltrán-Cobos, Fabiano Tavares, Manuel Cruz-Yusta, Luis Sánchez Granados, Mercedes Sánchez-Moreno and Ivana Pavlovic

ChemEngineering 2022, 6(5), 72; https://doi.org/10.3390/chemengineering6050072 - 20 Sep 2022

Cited by 4 | Viewed by 2526

Abstract

In recent decades, layered double hydroxides (LDH) have been proposed as innovative corrosion inhibitors for reinforced concrete. Their protective action is based on the ability to intercalate specific anions in the interlayer and on their ability to exchange the intercalated anion. In the [...] Read more.

In recent decades, layered double hydroxides (LDH) have been proposed as innovative corrosion inhibitors for reinforced concrete. Their protective action is based on the ability to intercalate specific anions in the interlayer and on their ability to exchange the intercalated anion. In the present study, an organically charged LDH, with sebacate anions in the interlayer (LDH-S), is proposed as a water-repellent additive for mortar. The waterproofing efficiency of LDH-S and the associated corrosion inhibition ability has been evaluated in reinforced mortar samples. A 42% decrease in the water capillary absorption coefficient has been estimated when 3% LHD-S is added to a mortar. Both the passivation processes of the steel rebars during the curing period and the initiation of corrosion due to chloride exposure have been studied by electrochemical measurements. Three different mortars have been evaluated: reference mortar (REF), mortar with Mg-Al LDH (LDH), and mortar with LDH-sebacate (LDH-S). The latter has shown an important protective capacity for preventing the initiation of corrosion by chloride penetration, with an inhibitory efficiency of 74%. The presence of LDHs without sebacate in the interlayer also improved the performance of the mortar against rebar corrosion, but with lower efficiency (23% inhibitory efficiency). However, this protection is lost after continued chloride exposure over time, and corrosion initiates similarly to the reference mortar. The low corrosion current density values registered when LDH-S is added to the mortar may be related to the increased electrical resistance recorded in this mortar. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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15 pages, 4380 KiB

Open AccessArticle

Drug-Containing Layered Double Hydroxide/Alginate Dispersions for Tissue Engineering

by Juan Pablo Zanin, German A. Gil, Mónica C. García and Ricardo Rojas

ChemEngineering 2022, 6(5), 70; https://doi.org/10.3390/chemengineering6050070 - 13 Sep 2022

Cited by 2 | Viewed by 2485

Abstract

Alginate (Alg) is increasingly studied as a constitutive material of scaffolds for tissue engineering because of its easy gelation and biocompatibility, and the incorporation of drugs into its formulation allows for its functionality to be extended. However, Alg presents a low cell adhesion [...] Read more.

Alginate (Alg) is increasingly studied as a constitutive material of scaffolds for tissue engineering because of its easy gelation and biocompatibility, and the incorporation of drugs into its formulation allows for its functionality to be extended. However, Alg presents a low cell adhesion and proliferation capacity, and the incorporation of drugs may further reduce its biocompatibility. Layered double hydroxides (LDH) are promising fillers for Alg-based biomaterials, as they increase cell adhesion and interaction and provide drug storage and controlled release. In this work, LDH containing ibuprofen or naproxen were synthesized by coprecipitation at a constant pH and their properties upon their incorporation in Alg dispersions (LDH-Drug/Alg) were explored. Drug release profiles in simulated body fluid and the proliferation of pre-osteoblastic MC3T3-E1 cells by LDH-Drug/Alg dispersions were then evaluated, leading to results that confirm their potential as biomaterials for tissue engineering. They showed a controlled release with diffusive control, modulated by the in-situ formation of an Alg hydrogel in the presence of Ca²⁺ ions. Additionally, LDH-Drug/Alg dispersions mitigated the cytotoxic effects of the pure drugs, especially in the case of markedly cytotoxic drugs such as naproxen. 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, 6352 KiB

Open AccessFeature PaperArticle

Preparation of Ca₂Al_1–mFe_m(OH)₆Cl·2H₂O-Doped Hydrocalumites and Application of Their Derived Mixed Oxides in the Photodegradation of Ibuprofen

by Alejandro Jiménez, Marta Valverde, Alexander Misol, Raquel Trujillano, Antonio Gil and Miguel Angel Vicente

ChemEngineering 2022, 6(4), 64; https://doi.org/10.3390/chemengineering6040064 - 18 Aug 2022

Cited by 7 | Viewed by 2286

Abstract

Aluminum from saline slags generated during the recycling of this metal, extracted under reflux conditions with aqueous NaOH, was used in the synthesis of hydrocalumite-type solids with the formula Ca₂Al_1–mFe_m(OH)₆Cl·2H₂O. The characterization of [...] Read more.

Aluminum from saline slags generated during the recycling of this metal, extracted under reflux conditions with aqueous NaOH, was used in the synthesis of hydrocalumite-type solids with the formula Ca₂Al_1–mFe_m(OH)₆Cl·2H₂O. The characterization of the obtained solids was carried out by powder X-ray diffraction, infrared spectroscopy, thermal analysis, element chemical analysis, N₂ adsorption-desorption at −196 °C and electron microscopy. The results showed the formation of Layered Double Hydroxide-type compounds whose characteristics varied as the amount of incorporated Fe³⁺ increased. These solids were calcined at 400 °C and evaluated for the catalytic photodegradation of ibuprofen, showing promising results in the elimination of this drug by advanced oxidation processes. The CaAl photocatalyst (without Fe) showed the best performance under UV light for the photodegradation of ibuprofen. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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11 pages, 2865 KiB

Open AccessArticle

Effect of Artificial Freeze/Thaw and Thermal Shock Ageing, Combined or Not with Salt Crystallisation on the Colour of Zamora Building Stones (Spain)

by Jacinta García-Talegón, Adolfo Carlos Iñigo, Rosa Sepúlveda and Eduardo Azofra

ChemEngineering 2022, 6(4), 61; https://doi.org/10.3390/chemengineering6040061 - 4 Aug 2022

Cited by 3 | Viewed by 2541

Abstract

After subjecting Zamora building stones to accelerated ageing tests, colour changes were studied, namely: (a) freezing/thawing and thermal shock (gelifraction and thermoclasty), and (b) combination of freezing/thawing plus thermal shock and salt crystallisation (sulphates or phosphates) (gelifraction, thermoclasty and haloclasty). Zamora building stones [...] Read more.

After subjecting Zamora building stones to accelerated ageing tests, colour changes were studied, namely: (a) freezing/thawing and thermal shock (gelifraction and thermoclasty), and (b) combination of freezing/thawing plus thermal shock and salt crystallisation (sulphates or phosphates) (gelifraction, thermoclasty and haloclasty). Zamora building stones are silicified conglomerates (silcretes) from the Cretaceous that show marked colour changes due to the remobilisation of iron oxyhydroxides. In this work, four varieties were: white stone; ochreous stone; white and red stone; and purple stone Their micromorphological characterization (skeleton, weathering plasma and porosity/cutan) is formed of grains and fragments of quartz and quartzite as well as by accesory minerals muscovite and feldspar (more or less altered), and some opaque. Quartz, feldspar and illite/mica were part of the skeleton; kaolinite, iron oxyhydroxides, and CT opal were part of the weathering plasma or cutans; their porosity were 11.7–8.7%. Their chromatic data have been statistically analysed (MANOVA-Biplot). They showed higher variations in ΔE*, ΔL*, Δa* and Δb*on combined freezing/thawing plus thermal shock and sulphates crystallisation leading to rapid alteration of the building stones. Chromatic differences between the other two artificial ageing tests were less evident and were not detected in all samples. The global effect of ageing on the Zamora building stones darkened them and reduced their yellowing. The ochreous stone suffered the least variation and the purple stone the most. This study of the colour by statistical analyse may be of interest for the evaluation and monitoring of stone decay, which is an inexpensive, simple, easy and non-destructive technique. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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16 pages, 1361 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

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 8 | Viewed by 2838

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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13 pages, 2807 KiB

Open AccessArticle

Acid-Modified Clays for the Catalytic Obtention of 5-Hydroxymethylfurfural from Glucose

by Vladimir Sánchez, María Dolores González, Pilar Salagre and Yolanda Cesteros

ChemEngineering 2022, 6(4), 57; https://doi.org/10.3390/chemengineering6040057 - 26 Jul 2022

Cited by 4 | Viewed by 2229

Abstract

5-hydroxymethylfurfural (5-HMF) is an important platform molecule for the synthesis of high-added value products. Several synthesized clay materials, such as mesoporous hectorite and fluorohectorite, in addition to commercial montmorillonite K-10, have been acid modified by different methodologies to be applied as catalysts for [...] Read more.

5-hydroxymethylfurfural (5-HMF) is an important platform molecule for the synthesis of high-added value products. Several synthesized clay materials, such as mesoporous hectorite and fluorohectorite, in addition to commercial montmorillonite K-10, have been acid modified by different methodologies to be applied as catalysts for the obtention of 5-HMF from glucose. The effects of the Brønsted and/or Lewis acidity, the reaction temperature and time, and the catalyst/glucose ratio on the conversion but especially on the selectivity to 5-HMF have been studied. By comparing the synthesized clays, the best selectivity to 5-HMF (36%) was obtained at 140 °C for 4 h with H-fluorohectorite because of the presence of strong Brønsted acid sites, although its conversion was the lowest (33%) due to its low amounts of Lewis acid sites. Different strategies, such as physical mixtures of montmorillonite K10, which contains high amounts of Lewis acid centers, with Amberlyst-15, which has high amounts of Brønsted acid sites, or the incorporation of rhenium compounds, were carried out. The best selectivity to 5-HMF (62%) was achieved with a mixture of 44 wt % Amberlyst-15 and 56 wt % of montmorillonite K10 for a 56% of conversion at 140 °C for 4 h. This proportion optimized the amount of Brønsted and Lewis acid sites in the catalyst under these reaction conditions. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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22 pages, 5736 KiB

Open AccessArticle

Photodegradation of Fipronil by Zn-AlPO₄ Materials Synthesized by Non-Hydrolytic Sol–Gel Method

by Omar José de Lima, Denis Talarico de Araújo, Liziane Marçal, Antonio Eduardo Miller Crotti, Guilherme Sippel Machado, Shirley Nakagaki, Emerson Henrique de Faria and Katia Jorge Ciuffi

ChemEngineering 2022, 6(4), 55; https://doi.org/10.3390/chemengineering6040055 - 13 Jul 2022

Cited by 3 | Viewed by 2619

Abstract

In recent decades, the increasing use of pesticides to improve food productivity has led to the release of effluents that contaminate the environment. To prepare a material that may help to treat effluents generated during agricultural practice, we used a new method based [...] Read more.

In recent decades, the increasing use of pesticides to improve food productivity has led to the release of effluents that contaminate the environment. To prepare a material that may help to treat effluents generated during agricultural practice, we used a new method based on the non-hydrolytic sol-gel route to obtain zinc photocatalysts in aluminophosphate matrixes. IR spectroscopy, X-ray diffraction, thermal analysis, differential scanning electron microscopy, energy dispersion spectroscopy, and specific surface area and pore volume determined from the nitrogen adsorbed were used to characterize materials treated at different temperatures. X-ray analysis showed how heat-treatment affected the structure of the material: Zn-AlPO₄ in the trigonal and orthorhombic phase was obtained at 750 and 1000 °C, respectively. These phases directly influenced the ability of the material to generate OH radicals. The capacity of the materials to treat effluents was tested in the photodegradation of the pesticide Fipronil. The photocatalytic reactions were monitored by ultraviolet-visible spectroscopy and gas chromatography-mass spectrometry analyses. Zn-AlPO₄ treated at 750 °C showed better photodegradation results--it removed 80% of the pesticide in 2 h when higher mass (150 mg) was tested. Long-time treatment of the effluent with Zn-AlPO₄ treated at 750 °C completely photodegraded Fipronil. GC-MS analysis confirmed the photodegration profile, and only traces of Fipronil were observed after photocatalytic reaction for 120 min in the presence of Zn-AlPO₄ treated at 750 °C under UV radiation. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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11 pages, 3987 KiB

Open AccessArticle

Nanoparticle Black Ceramic Pigment Obtained by Hydrotalcite-like Compound Microwave Treatment

by María Oset, Alejandro Moya, Guillermo Paulo-Redondo and Isaac Nebot-Díaz

ChemEngineering 2022, 6(4), 54; https://doi.org/10.3390/chemengineering6040054 - 11 Jul 2022

Cited by 3 | Viewed by 2287

Abstract

Development of ceramic pigments with controlled particle sizes below 1 µm is essential for the preparation of ceramic inks used in inkjet digital decoration that is currently being applied in the ceramics sector. A black ceramic pigment based on NiCoCrFe composition has been [...] Read more.

Development of ceramic pigments with controlled particle sizes below 1 µm is essential for the preparation of ceramic inks used in inkjet digital decoration that is currently being applied in the ceramics sector. A black ceramic pigment based on NiCoCrFe composition has been prepared using thermal decomposition of hydrotalcite-like compounds. The stoichiometry ratio between different cations was studied to obtain the blackest pigment, giving Ni_0,5Co_0,5CrFeO₄ the better cation ratio, also the thermal treatment, comparing traditional firing in an electric furnace with microwave treatment. Samples have been characterized by X-ray diffraction, Scanning Electron Microscopy and Lab colour measurement. Microwave treatment showed the best way to obtain a pigment with spinel-type structure and a homogeneous size distribution near to 150 nm, with a high intensity and colorimetric data, reducing drastically the temperature and energy consumption to obtain a black ceramic pigment suitable to be utilized in digital ceramic inks. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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19 pages, 5666 KiB

Open AccessArticle

Use of Ethylamine, Diethylamine and Triethylamine in the Synthesis of Zn,Al Layered Double Hydroxides

by Alexander Misol, Alejandro Jiménez and Francisco M. Labajos

ChemEngineering 2022, 6(4), 53; https://doi.org/10.3390/chemengineering6040053 - 6 Jul 2022

Cited by 4 | Viewed by 3552

Abstract

Amines with two carbon atoms in the organic chain [ethylamine (EA), diethylamine (DEA), triethylamine (TEA)] have been used as precipitant agents to obtain a hydrotalcite-like compound with Zn (II) and Al (III) as layered cations and with nitrate anions in the interlayered region [...] Read more.

Amines with two carbon atoms in the organic chain [ethylamine (EA), diethylamine (DEA), triethylamine (TEA)] have been used as precipitant agents to obtain a hydrotalcite-like compound with Zn (II) and Al (III) as layered cations and with nitrate anions in the interlayered region to balance the charge. This Layered Double Hydroxide was prepared following the coprecipitation method, and the effect on the crystal and particle sizes was studied. Also, the effect of submitting the obtained solids to hydrothermal post-synthesis treatment by conventional heating and microwave assisted heating were studied. The obtained solids were exhaustively characterized using several instrumental techniques, such as X-ray diffraction, Thermal Analysis (DTA and TG), Chemical Analysis, Infrared Spectroscopy (FT-IR), determination of Particle Size Distribution and BET-Surface area. Well crystallized solids were obtained showing two possible LDH phases, depending on the orientation of the interlayer anion with respect to the brucite-like layers. The results indicated that there is a certain influence of the amine, when used as a precipitating agent, and as a consequence of the degree of substitution, on the crystallinity and particle size of the final solid obtained. The LDHs obtained using TEA exhibited higher crystallinity, which was improved after a long hydrothermal treatment by conventional heating. Regarding the shape of the particles, the formation of aggregates in the former solid was detected, which could be easily disintegrated using ultrasound treatments, producing solid powder with high crystallinity and small particle size, with homogeneous size distribution. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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11 pages, 3518 KiB

Open AccessArticle

Graphene-Wine Waste Derived Carbon Composites for Advanced Supercapacitors

by Violeta Ureña-Torres, Gelines Moreno-Fernández, Juan Luis Gómez-Urbano, Miguel Granados-Moreno and Daniel Carriazo

ChemEngineering 2022, 6(4), 49; https://doi.org/10.3390/chemengineering6040049 - 29 Jun 2022

Cited by 2 | Viewed by 2830

Abstract

In this work, we investigate the potential of a novel carbon composite as an electrode for high-voltage electrochemical double-layer capacitors. The carbon composite was prepared following a sustainable synthetic approach that first involved the pyrolysis and then the activation of a precursor formed [...] Read more.

In this work, we investigate the potential of a novel carbon composite as an electrode for high-voltage electrochemical double-layer capacitors. The carbon composite was prepared following a sustainable synthetic approach that first involved the pyrolysis and then the activation of a precursor formed by winery wastes and graphene oxide. The composite prepared in this way shows a very high specific surface area (2467 m²·g⁻¹) and an optimum pore size distribution for their use in supercapacitor electrodes. Graphene-biowaste-derived carbon composites are tested as active electrode materials in two different non-aqueous electrolytes, the ammonium salt-based conventional organic electrolyte and one imidazolium-based ionic liquid (1 M Et₄NBF₄/ACN and EMINTFSI). It was found that the presence of graphene oxide led to significant morphological and textural changes, which result in high-energy and power densities of ~27 W·h·kg⁻¹ at 13,026 W·kg⁻¹. Moreover, the devices assembled retain above 70% of the initial capacitance after 6000 cycles in the case of the organic electrolyte. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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20 pages, 5456 KiB

Open AccessArticle

Hydrogen and CNT Production by Methane Cracking Using Ni–Cu and Co–Cu Catalysts Supported on Argan-Derived Carbon

by Fernando Cazaña, Zainab Afailal, Miguel González-Martín, José Luis Sánchez, Nieves Latorre, Eva Romeo, Jesús Arauzo and Antonio Monzón

ChemEngineering 2022, 6(4), 47; https://doi.org/10.3390/chemengineering6040047 - 27 Jun 2022

Cited by 7 | Viewed by 3446

Abstract

The 21st century arrived with global growth of energy demand caused by population and standard of living increases. In this context, a suitable alternative to produce COx-free H₂ is the catalytic decomposition of methane (CDM), which also allows for obtaining high-value-added carbonaceous [...] Read more.

The 21st century arrived with global growth of energy demand caused by population and standard of living increases. In this context, a suitable alternative to produce COx-free H₂ is the catalytic decomposition of methane (CDM), which also allows for obtaining high-value-added carbonaceous nanomaterials (CNMs), such as carbon nanotubes (CNTs). This work presents the results obtained in the co-production of CO_x-free hydrogen and CNTs by CDM using Ni–Cu and Co–Cu catalysts supported on carbon derived from Argan (Argania spinosa) shell (ArDC). The results show that the operation at 900 °C and a feed-ratio CH₄:H₂ = 2 with the Ni–Cu/ArDC catalyst is the most active, producing 3.7 g_C/g_metal after 2 h of reaction (equivalent to average hydrogen productivity of 0.61 g H₂/g_metal∙h). The lower productivity of the Co–Cu/ArDC catalyst (1.4 g_C/g_metal) could be caused by the higher proportion of small metallic NPs (<5 nm) that remain confined inside the micropores of the carbonaceous support, hindering the formation and growth of the CNTs. The TEM and Raman results indicate that the Co–Cu catalyst is able to selectively produce CNTs of high quality at temperatures below 850 °C, attaining the best results at 800 °C. The results obtained in this work also show the elevated potential of Argan residues, as a representative of other lignocellulosic raw materials, in the development of carbonaceous materials and nanomaterials of high added-value. 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, 2721 KiB

Open AccessArticle

Esterification of Levulinic Acid to Methyl Levulinate over Zr-MOFs Catalysts

by Daiana A. Bravo Fuchineco, Angélica C. Heredia, Sandra M. Mendoza, Enrique Rodríguez-Castellón and Mónica E. Crivello

ChemEngineering 2022, 6(2), 26; https://doi.org/10.3390/chemengineering6020026 - 25 Mar 2022

Cited by 10 | Viewed by 3791

Abstract

At present, the trend towards partial replacement of petroleum-derived fuels by those from the revaluation of biomass has become of great importance. An effective strategy for processing complex biomass feedstocks involves prior conversion to simpler compounds (platform molecules) that are more easily transformed [...] Read more.

At present, the trend towards partial replacement of petroleum-derived fuels by those from the revaluation of biomass has become of great importance. An effective strategy for processing complex biomass feedstocks involves prior conversion to simpler compounds (platform molecules) that are more easily transformed in subsequent reactions. This study analyzes the metal–organic frameworks (MOFs) that contain Zr metal clusters formed by ligands of terephthalic acid (UiO-66) and aminoterephthalic acid (UiO-66-NH₂), as active and stable catalysts for the esterification of levulinic acid with methanol. An alternative synthesis is presented by means of ultrasonic stirring at room temperature and 60 °C, in order to improve the structural properties of the catalysts. They were analyzed by X-ray diffraction, scanning electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, microwave plasma atomic emission spectroscopy, acidity measurement, and N₂ adsorption. The catalytic reaction was carried out in a batch system and under pressure in an autoclave. Its progress was followed by gas chromatography and mass spectrometry. Parameters such as temperature, catalyst mass, and molar ratio of reactants were optimized to improve the catalytic performance. The MOF that presented the highest activity and selectivity to the desired product was obtained by synthesis with ultrasound and 60 °C with aminoterephthalic acid. The methyl levulinate yield was 67.77% in batch at 5 h and 85.89% in an autoclave at 1 h. An analysis of the kinetic parameters of the reaction is presented. The spent material can be activated by ethanol washing allowing the catalytic activity to be maintained in the recycles. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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Review

Jump to: Editorial, Research

24 pages, 1970 KiB

Open AccessFeature PaperReview

Mesoporous Silica-Based Catalysts for Biodiesel Production: A Review

by Is Fatimah, Ganjar Fadillah, Suresh Sagadevan, Won-Chun Oh and Keshav Lalit Ameta

ChemEngineering 2023, 7(3), 56; https://doi.org/10.3390/chemengineering7030056 - 16 Jun 2023

Cited by 16 | Viewed by 3806

Abstract

High demand for energy consumption forced the exploration of renewable energy resources, and in this context, biodiesel has received intensive attention. The process of biodiesel production itself needs to be optimized in order to make it an eco-friendly and high-performance energy resource. Within [...] Read more.

High demand for energy consumption forced the exploration of renewable energy resources, and in this context, biodiesel has received intensive attention. The process of biodiesel production itself needs to be optimized in order to make it an eco-friendly and high-performance energy resource. Within this scheme, development of low-cost and reusable heterogeneous catalysts has received much attention. Mesoporous silica materials with the characteristics of having a high surface area and being modifiable, tunable, and chemical/thermally stable have emerged as potential solid support of powerful catalysts in biodiesel production. This review highlights the latest updates on mesoporous silica modifications including acidic, basic, enzyme, and bifunctional catalysts derived from varied functionalization. In addition, the future outlook for progression is also discussed in detail. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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17 pages, 3128 KiB

Open AccessReview

Overview on Photoreforming of Biomass Aqueous Solutions to Generate H₂ in the Presence of g-C₃N₄-Based Materials

by E. I. García-López, L. Palmisano and G. Marcì

ChemEngineering 2023, 7(1), 11; https://doi.org/10.3390/chemengineering7010011 - 3 Feb 2023

Cited by 12 | Viewed by 3087

Abstract

Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass [...] Read more.

Photoreforming (PR) of biomass can be considered a viable technology under mild experimental conditions to produce hydrogen with a high reaction rate using compounds from renewable resources and waste materials. The application of biomass PR gives rise to both hydrogen generation and biomass waste valorization. The process could be scaled up to obtain hydrogen under natural sunlight irradiation, and research on polymeric carbon nitride (g-C₃N₄)-based photocatalysts has been widely carried out in recent years. The non-metallic-based carbon nitride materials are economical and (photo)stable polymer semiconductors, and their physicochemical surface and electronic properties are optimal for obtaining H_2, which can be considered a gas that does not cause major environmental problems. Some hindrances related to their structure, such as the low absorption of visible light and the relatively high recombination rate of electron-hole pairs, restrict the performance; therefore, it is necessary to improve their activity and the yield of the reaction by modifying them in various ways. Various types of solutions have been proposed in this regard, such as, for example, their coupling with other semiconductors to form composite materials. The current mini-review aims to overview the PR field, reporting some of the most interesting papers devoted to understanding the role of g-C₃N₄ in biomass PR. Information on many physico-chemical aspects related to the performance of the process and possible ways to obtain better results than those present up to now in the literature will be reported. 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, 3650 KiB

Open AccessReview

Review of the Application of Hydrotalcite as CO₂ Sinks for Climate Change Mitigation

by David Suescum-Morales, José Ramón Jiménez and José María Fernández-Rodríguez

ChemEngineering 2022, 6(4), 50; https://doi.org/10.3390/chemengineering6040050 - 1 Jul 2022

Cited by 7 | Viewed by 4427

Abstract

In recent decades, the environmental impact caused by greenhouse gases, especially CO₂, has driven many countries to reduce the concentration of these gases. The study and development of new designs that maximise the efficiency of CO₂ capture continue to be [...] Read more.

In recent decades, the environmental impact caused by greenhouse gases, especially CO₂, has driven many countries to reduce the concentration of these gases. The study and development of new designs that maximise the efficiency of CO₂ capture continue to be topical. This paper presents a review of the application of hydrotalcites as CO₂ sinks. There are several parameters that can make hydrotalcites suitable for use as CO₂ sinks. The first question is the use of calcined or uncalcined hydrotalcite as well as the temperature at which it is calcined, since the calcination conditions (temperature, rate and duration) are important parameters determining structure recovery. Other aspects were also analysed: (i) the influence of the pH of the synthesis; (ii) the molar ratio of its main elements; (iii) ways to increase the specific area of hydrotalcites; (iv) pressure, temperature, humidity and time in CO₂ absorption; and (v) combined use of hydrotalcites and cement-based materials. A summary of the results obtained so far in terms of CO₂ capture with the parameters described above is presented. This work can be used as a guide to address CO₂ capture with hydrotalcites by showing where the information gaps are and where researchers should apply their efforts. Full article

(This article belongs to the Special Issue A Themed Issue in Honor of Prof. Dr. Vicente Rives)

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44 pages, 3369 KiB

Open AccessReview

Layered Double Hydroxide/Nanocarbon Composites as Heterogeneous Catalysts: A Review

by Didier Tichit and Mayra G. Álvarez

ChemEngineering 2022, 6(4), 45; https://doi.org/10.3390/chemengineering6040045 - 22 Jun 2022

Cited by 11 | Viewed by 3505

Abstract

The synthesis and applications of composites based on layered double hydroxides (LDHs) and nanocarbons have recently seen great development. On the one hand, LDHs are versatile 2D compounds that present a plethora of applications, from medicine to energy conversion, environmental remediation, and heterogeneous [...] Read more.

The synthesis and applications of composites based on layered double hydroxides (LDHs) and nanocarbons have recently seen great development. On the one hand, LDHs are versatile 2D compounds that present a plethora of applications, from medicine to energy conversion, environmental remediation, and heterogeneous catalysis. On the other, nanocarbons present unique physical and chemical properties owing to their low-dimensional structure and sp² hybridization of carbon atoms, which endows them with excellent charge carrier mobility, outstanding mechanical strength, and high thermal conductivity. Many reviews described the applications of LDH/nanocarbon composites in the areas of energy and photo- and electro-catalysis, but there is still scarce literature on their latest applications as heterogeneous catalysts in chemical synthesis and conversion, which is the object of this review. First, the properties of the LDHs and of the different types of carbon materials involved as building blocks of the composites are summarized. Then, the synthesis methods of the composites are described, emphasizing the parameters allowing their properties to be controlled. This highlights their great adaptability and easier implementation. Afterwards, the application of LDH/carbon composites as catalysts for C–C bond formation, higher alcohol synthesis (HAS), oxidation, and hydrogenation reactions is reported and discussed in depth. 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

Open AccessEditor’s ChoiceReview

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 6 | Viewed by 3401

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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