Research

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16 pages, 23832 KiB

Open AccessArticle

Bacterial Cellulose and Biodegradable Superbase for Heterogeneous Transesterification to Alkyl Esters

by Cristina Ionela Gogoaşă, Cristian Eugen Răducanu, Laura Elisabeta Petraş, Doinița Roxana Cioroiu Tîrpan, Gabriel Vasilievici, Andreea Luiza Mîrţ, Tănase Dobre and Oana Cristina Pârvulescu

Catalysts 2023, 13(11), 1431; https://doi.org/10.3390/catal13111431 - 13 Nov 2023

Cited by 1 | Viewed by 875

Abstract

Heterogeneous catalysts, basic, acidic or bifunctional, can catalyze transesterification reactions where the raw material has a significant content of FFA fatty acids, such as used cooking oils or other lipid-based residues, which do not have the purity required for homogeneous catalysis, in which [...] Read more.

Heterogeneous catalysts, basic, acidic or bifunctional, can catalyze transesterification reactions where the raw material has a significant content of FFA fatty acids, such as used cooking oils or other lipid-based residues, which do not have the purity required for homogeneous catalysis, in which case the purity of the triglycerides above 99.5% is the first condition for the initiation of the reaction, to avoid saponification. In this work, a green supported catalyst was developed, using bacterial cellulose as catalytic support and biodegradable superbase as a chemical compound, for transesterification reaction to obtain alkyl esters, yielding over 99% of its content at 70 °C temperature and 7.5% catalyst loading (1.5/20 w/w catalyst:oil). A Plackett-–Burman design was used for screening experiments to explore the main effect in terms of catalytic activity and performance of the triglyceride conversion reaction. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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18 pages, 5375 KiB

Open AccessFeature PaperArticle

Efficient Synthesis of Furfural from Corncob by a Novel Biochar-Based Heterogeneous Chemocatalyst in Choline Chloride: Maleic Acid–Water

by Linsong Yang, Yucheng Li, Yuqi Wu, Yucai He and Cuiluan Ma

Catalysts 2023, 13(9), 1277; https://doi.org/10.3390/catal13091277 - 05 Sep 2023

Viewed by 936

Abstract

The use of plentiful and renewable feedstock for producing chemicals is fundamental for the development of sustainable chemical processes. Using fish scale as a biobased carrier, a novel biochar SO₄²⁻/SnO₂-FFS heterogeneous chemocatalyst was prepared to catalyze furfural production [...] Read more.

The use of plentiful and renewable feedstock for producing chemicals is fundamental for the development of sustainable chemical processes. Using fish scale as a biobased carrier, a novel biochar SO₄²⁻/SnO₂-FFS heterogeneous chemocatalyst was prepared to catalyze furfural production from xylose-rich corncob-hydrolysates obtained from acid hydrolysis of corncob in a deep eutectic solvent (DES)–water system. By characterizing the physical as well as chemical properties of SO₄²⁻/SnO₂-FFS by NH₃-TPD, FT-IR, XPS, XRD, and SEM, it was shown that the chemocatalyst had Lewis/Brönsted acid centers, and its surface roughness could be well expanded to contact substrates. The corncob was initially hydrolyzed at 140 °C to obtain xylose-rich hydrolysate. Subsequently, SO₄²⁻/SnO₂-FFS (3.6 wt.%) was used to catalyze the corn cob hydrolysate containing D-xylose (20.0 g/L) at a reaction temperature of 170 °C for 15 min. Additionally, ZnCl₂ (20.0 g/L) was added. Ultimately, furfural (93.8 mM, 70.5% yield) was produced in the deep eutectic solvent ChCl:maleic acid–water (DES_MLA–water = 10:90, v/v). A synergistic catalytic mechanism for transforming xylose-rich corncob-hydrolysate into furfural and byproducts were proposed using SO₄²⁻/SnO₂-FFS as a chemocatalyst in DES_MLA–water containing ZnCl₂. Consequently, the efficient use of biochar SO₄²⁻/SnO₂-FFS chemocatalysts for the sustainable synthesis of biobased furan compounds from biomass holds great promise in the future. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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18 pages, 10903 KiB

Open AccessArticle

Promoting Effects of Copper and Iron on Ni/MSN Catalysts for Methane Decomposition

by Nur Shamimie Nadzwin Hasnan, Manoj Pudukudy, Zahira Yaakob, Nur Hidayatul Nazirah Kamarudin, Kean Long Lim and Sharifah Najiha Timmiati

Catalysts 2023, 13(7), 1067; https://doi.org/10.3390/catal13071067 - 03 Jul 2023

Cited by 2 | Viewed by 1206

Abstract

Copper and iron-based bimetallic nickel catalysts supported on Mesostructured Silica Nanoparticles (MSNs) with compositions of 50% Ni–5% Cu/MSN and 50% Ni–5% Fe/MSN were prepared using an impregnation method, and they were compared with a monometallic 50% Ni–MSN catalyst for their activity and stability [...] Read more.

Copper and iron-based bimetallic nickel catalysts supported on Mesostructured Silica Nanoparticles (MSNs) with compositions of 50% Ni–5% Cu/MSN and 50% Ni–5% Fe/MSN were prepared using an impregnation method, and they were compared with a monometallic 50% Ni–MSN catalyst for their activity and stability in methane decomposition reaction. The influence of promoters, such as Cu and Fe, at different reaction temperatures (700 °C, 800 °C and 900 °C) was investigated. The results revealed that the Cu and Fe-promoted catalysts significantly increased the hydrogen yield in methane decomposition compared with the unpromoted catalyst. This could be attributed to the formation of Ni–Cu and Ni–Fe bimetallic alloys in the catalysts, respectively, and this favored the stability of the catalysts. With increasing reaction temperature, the hydrogen yield also increased. However, the hydrogen yield and the lifetime of the nickel catalyst were enhanced upon the addition of iron compared to copper at all the reaction temperatures. The analysis conducted over the spent catalysts validated the formation of multi-walled carbon nanotubes with a bamboo-like internal channel over the catalysts along with a high crystallinity and graphitization degree of the carbon produced. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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10 pages, 11754 KiB

Open AccessCommunication

Synthesis of a Series of Methyl Benzoates through Esterification with a Zr/Ti Solid Acid Catalyst

by Xiaofeng Yu, Chunjie Shi, Yueling Cheng, Yejing Zhu, Renyuan Song and Shengfei Hu

Catalysts 2023, 13(5), 915; https://doi.org/10.3390/catal13050915 - 22 May 2023

Viewed by 2071

Abstract

Methyl benzoate (MB) compounds are prepared by reacting various benzoic acids with methanol using an acidic catalyst. In this study, the solid acids of zirconium metal solids fixed with various substances were studied. We determined that zirconium metal catalysts with fixed Ti had [...] Read more.

Methyl benzoate (MB) compounds are prepared by reacting various benzoic acids with methanol using an acidic catalyst. In this study, the solid acids of zirconium metal solids fixed with various substances were studied. We determined that zirconium metal catalysts with fixed Ti had the best activity. The catalytic synthesis of a series of MB compounds using titanium zirconium solid acids was studied. The direct condensation of benzoic acid and methanol using a metallic Lewis acid without other auxiliary Bronsted acids is reported for the first time. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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13 pages, 2386 KiB

Open AccessFeature PaperArticle

Catalytic Conversion of Sugars into Lactic Acid via a RuO_x/MoS₂ Catalyst

by Zongling Li, Pengfei Wu, Jifeng Pang, Xianquan Li, Shangru Zhai and Mingyuan Zheng

Catalysts 2023, 13(3), 545; https://doi.org/10.3390/catal13030545 - 08 Mar 2023

Cited by 5 | Viewed by 1590

Abstract

The catalytic transformation of sugars into lactic acid has shown great potential for the scalable utilization of renewable biomass. Herein, RuO_x/MoS₂ catalysts were synthesized with the assistance of CaO for the one-pot conversion of glucose to lactic acid. Under the [...] Read more.

The catalytic transformation of sugars into lactic acid has shown great potential for the scalable utilization of renewable biomass. Herein, RuO_x/MoS₂ catalysts were synthesized with the assistance of CaO for the one-pot conversion of glucose to lactic acid. Under the reaction conditions of 120 °C and 1 MPa O₂, a 96.6% glucose conversion and a 54.3% lactic acid selectivity were realized in the one-pot catalytic reaction, with relatively high stability after four successive cycles. This catalytic system was also effective for the conversion of many other carbohydrate substrates, such as fructose, xylose and cellulose (selectivity 68.9%, 78.2% and 50.6%, respectively). According to catalyst characterizations and conditional experiments, the highly dispersed RuO_x species on the surface of MoS₂, together with OH⁻, promoted isomerization, retro-aldol condensation, dehydration and hydration reactions, resulting in a relatively high lactic acid yield for sugar conversions. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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10 pages, 2825 KiB

Open AccessFeature PaperArticle

Homogeneous Photo-Fenton Degradation and Mineralization of Model and Simulated Pesticide Wastewaters in Lab- and Pilot-Scale Reactors

by Chrysanthi Berberidou, Petros Kokkinos, Ioannis Poulios and Dionissios Mantzavinos

Catalysts 2022, 12(12), 1512; https://doi.org/10.3390/catal12121512 - 25 Nov 2022

Cited by 3 | Viewed by 1182

Abstract

The homogeneous photocatalytic degradation of model pesticide clopyralid (CLPR) has been investigated under various experimental setups. Lab-scale experiments under UV-A radiation in an acidic environment showed that the degradation rate generally increased when increasing either Fe³⁺ or H₂O₂ concentration [...] Read more.

The homogeneous photocatalytic degradation of model pesticide clopyralid (CLPR) has been investigated under various experimental setups. Lab-scale experiments under UV-A radiation in an acidic environment showed that the degradation rate generally increased when increasing either Fe³⁺ or H₂O₂ concentration up to a point beyond which (i.e., 100 mg L⁻¹ for peroxide or 7 mg L⁻¹ for ferric ions) Fenton reagents had little or even detrimental effect on degradation. Thus, there is an optimum concentration of Fenton reagents for maximizing treatment performance, beyond which degradation rates are not enhanced. Excessive concentrations of peroxide and/or catalyst may (i) introduce unnecessary treatment costs, (ii) reduce performance due to scavenging effects, and (iii) raise environmental concerns associated with the disposal of, e.g., high concentrations of iron in the receiving water courses. Switching from UV-A to visible light led to similar rates of degradation, i.e., 86% and 82.2%, respectively, after 90 min of reaction, highlighting the potential of using renewable energy, i.e., natural sunlight, to drive the process. Treatment for 120 min also led to 90% mineralization and quantitative release of nitrogen originally present in the pesticide; this was also accompanied by complete elimination of eco-toxicity to Vibrio fischeri. Pilot-scale experiments were performed in a fountain-type reactor using a commercial pesticide formulation containing CLPR. Both the degradation and mineralization rates increased with increasing the intensity of the incident UV-A radiation from 1.88 to 4.03 mW cm⁻². Experiments were also conducted with different liquid volumes, i.e., from 3 to 8 L. Illumination of 5 L wastewater resulted in 80% mineralization after 60 min and this only slightly decreased to 73% at 8 L. Overall, the findings underline the promising perspectives of the application of the treatment method in upgrading the quality of water and liquid waste containing pesticides. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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17 pages, 6585 KiB

Open AccessFeature PaperArticle

Effects of Site Geometry and Local Composition on Hydrogenation of Surface Carbon to Methane on Ni, Co, and NiCo Catalysts

by Sebastian Godoy, Prashant Deshlahra, Francisco Villagra-Soza, Alejandro Karelovic and Romel Jimenez

Catalysts 2022, 12(11), 1380; https://doi.org/10.3390/catal12111380 - 07 Nov 2022

Viewed by 1441

Abstract

Surface carbon deposits deactivate Ni and Co catalysts in reactions involving hydrocarbons and CO_x. Electronic properties, adsorption energies of H, C, and CH_x species, and the energetics of the hydrogenation of surface C atom to methane are studied for (100) [...] Read more.

Surface carbon deposits deactivate Ni and Co catalysts in reactions involving hydrocarbons and CO_x. Electronic properties, adsorption energies of H, C, and CH_x species, and the energetics of the hydrogenation of surface C atom to methane are studied for (100) and (111) surfaces of monometallic Ni and Co, and bimetallic NiCo. The bimetallic catalyst exhibits a Co→Ni electron donation and a concomitant increase in the magnetization of Co atoms. The CH_x species resulting from sequential hydrogenation are more stable on Co than on Ni atoms of the NiCo surfaces due to more favorable (C-H)–Co agostic interactions. These interactions and differences between Co and Ni sites are more significant for (111) than for (100) bimetallic surfaces. On (111) surfaces, CH is the most stable species, and the first hydrogenation of C atom exhibits the highest barrier, followed by the CH₃ hydrogenation steps. In contrast, on (100) surfaces, surface C atom is the most stable species and CH₂ or *CH₃ hydrogenations exhibit the highest barriers. The Gibbs free energy profiles suggest that C removal on (111) surfaces is thermodynamically favorable and exhibits a lower barrier than on the (100) surfaces. Thus, the (100) surfaces, especially Ni(100), are more prone to C poisoning. The NiCo(100) surfaces exhibit weaker binding of C and CH_x species than Ni(100) and Co(100), which improves C poisoning resistance and lowers hydrogenation barriers. These results show that the electronic effects of alloying Ni and Co strongly depend on the local site composition and geometry. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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Review

Jump to: Research

25 pages, 3347 KiB

Open AccessReview

A Review of Biomass-Derived Heterogeneous Catalysts for Biodiesel Production

by Somasundaram Chandra Kishore, Suguna Perumal, Raji Atchudan, Ashok K. Sundramoorthy, Muthulakshmi Alagan, Sambasivam Sangaraju and Yong Rok Lee

Catalysts 2022, 12(12), 1501; https://doi.org/10.3390/catal12121501 - 23 Nov 2022

Cited by 8 | Viewed by 3095

Abstract

The scientific community is being forced to consider alternative renewable fuels such as biodiesel as a result of the sharp increases in the price of petroleum and the increased demand for petroleum-derived products. Transesterification is a technique used to create biodiesel where a [...] Read more.

The scientific community is being forced to consider alternative renewable fuels such as biodiesel as a result of the sharp increases in the price of petroleum and the increased demand for petroleum-derived products. Transesterification is a technique used to create biodiesel where a variety of edible oils, non-edible oils, and animal fats are used. For this, either a homogeneous or heterogeneous catalyst is utilized. An appropriate catalyst is chosen based on the quantity of free fatty acid content in the oil. The main distinction between homogeneous and heterogeneous catalysts is that compared to the heterogeneous catalyst, the homogeneous catalyst is not affected by the quantity of free fatty acids in the oil. Early methods of producing biodiesel relied on homogeneous catalysts, which have drawbacks such as high flammability, toxicity, corrosion, byproducts such as soap and glycerol, and high wastewater output. The majority of these issues are solved by heterogeneous catalysts. Recent innovations use novel heterogeneous catalysts that are obtained from biomass and biowaste resources. Numerous researchers have documented the use of biomass-derived heterogeneous catalysts in the production of high-quality, pure biodiesel as a potentially greener manufacturing method. The catalysts were significantly altered through conventional physical processes that were both cost- and energy-effective. The present review is intended to analyze catalysts from biowaste for making biodiesel at a minimal cost. The most recent methods for creating diverse kinds of catalysts—including acidic, basic, bifunctional, and nanocatalysts—from various chemicals and biomass are highlighted in this review. Additionally, the effects of various catalyst preparation methods on biodiesel yield are thoroughly explored. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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34 pages, 38054 KiB

Open AccessReview

A Review of CeO₂ Supported Catalysts for CO₂ Reduction to CO through the Reverse Water Gas Shift Reaction

by Parisa Ebrahimi, Anand Kumar and Majeda Khraisheh

Catalysts 2022, 12(10), 1101; https://doi.org/10.3390/catal12101101 - 23 Sep 2022

Cited by 31 | Viewed by 7070

Abstract

The catalytic conversion of CO₂ to CO by the reverse water gas shift (RWGS) reaction followed by well-established synthesis gas conversion technologies could be a practical technique to convert CO₂ to valuable chemicals and fuels in industrial settings. For catalyst developers, [...] Read more.

The catalytic conversion of CO₂ to CO by the reverse water gas shift (RWGS) reaction followed by well-established synthesis gas conversion technologies could be a practical technique to convert CO₂ to valuable chemicals and fuels in industrial settings. For catalyst developers, prevention of side reactions like methanation, low-temperature activity, and selectivity enhancements for the RWGS reaction are crucial concerns. Cerium oxide (ceria, CeO₂) has received considerable attention in recent years due to its exceptional physical and chemical properties. This study reviews the use of ceria-supported active metal catalysts in RWGS reaction along with discussing some basic and fundamental features of ceria. The RWGS reaction mechanism, reaction kinetics on supported catalysts, as well as the importance of oxygen vacancies are also explored. Besides, recent advances in CeO₂ supported metal catalyst design strategies for increasing CO₂ conversion activity and selectivity towards CO are systematically identified, summarized, and assessed to understand the impacts of physicochemical parameters on catalytic performance such as morphologies, nanosize effects, compositions, promotional abilities, metal-support interactions (MSI) and the role of selected synthesis procedures for forming distinct structural morphologies. This brief review may help with future RWGS catalyst design and optimization. Full article

(This article belongs to the Special Issue Applications of Heterogeneous Catalysts in Green Chemistry)

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