Catalysts

15 pages, 788 KiB

Open AccessArticle

Immobilized Phosphotriesterase as an Enzymatic Resolution for Sofosbuvir Precursor

by Weerapha Panatdasirisuk, Suthathip Phetlum, Thanat Tiyasakulchai, Nitipol Srimongkolpithak, Tanaporn Uengwetwanit and Nongluck Jaito

Catalysts 2025, 15(4), 339; https://doi.org/10.3390/catal15040339 (registering DOI) - 31 Mar 2025

Abstract

The enzymatic resolution of chiral sofosbuvir precursors is a critical step in producing stereoisomerically pure ProTide drugs, essential for their therapeutic efficacy. In this study, a mutated phosphotriesterase (W131M-PTE) was immobilized onto various polymeric macroporous beads, including commercial immobead 150P (IB), modified (IB-EDA [...] Read more.

The enzymatic resolution of chiral sofosbuvir precursors is a critical step in producing stereoisomerically pure ProTide drugs, essential for their therapeutic efficacy. In this study, a mutated phosphotriesterase (W131M-PTE) was immobilized onto various polymeric macroporous beads, including commercial immobead 150P (IB), modified (IB-EDA and IB-MTD), and synthetic polyacrylamide (PAM) beads functionalized with glutaraldehyde (PAM-GA) or 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (PAM-EDC). The immobilization efficiency, stability, and reusability of the enzyme were systematically evaluated. Among the tested supports, PAM-EDC demonstrated superior performance, retaining high enzymatic activity across multiple cycles and achieving a 92% yield of the (Sp)-diastereomer. The study highlights the potential of immobilized W131M-PTE as a cost-effective and scalable solution for chiral separation in pharmaceutical manufacturing, with implications for broader applications in ProTide drug production. Full article

(This article belongs to the Topic Green and Sustainable Chemical Processes)

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17 pages, 3121 KiB

Open AccessArticle

Carbon-Encapsulated Ni Nanoparticles Catalysts Derived from Ni-Hexamine Coordination Frameworks for Oxygen Reduction Reaction and Oxygen Evolution Reaction

by Huoxing Huang, Jiaxing Huang, Guoyu Zhong, Shurui Xu, Hongwei Chen, Xiaobo Fu, Shimin Kang, Junling Tu, Yongxiao Tuo, Wenbo Liao and Baizeng Fang

Catalysts 2025, 15(4), 338; https://doi.org/10.3390/catal15040338 (registering DOI) - 31 Mar 2025

Abstract

Developing efficient bifunctional oxygen reduction (ORR) and oxygen evolution (OER) electrocatalysts is critical for renewable energy technologies. Noble metal catalysts face limitations in cost, scarcity, and bifunctional compatibility. Herein, we report the synthesis of nickel nanoparticles encapsulated in nitrogen-doped carbon nanosheets (Ni@NC-T) via [...] Read more.

Developing efficient bifunctional oxygen reduction (ORR) and oxygen evolution (OER) electrocatalysts is critical for renewable energy technologies. Noble metal catalysts face limitations in cost, scarcity, and bifunctional compatibility. Herein, we report the synthesis of nickel nanoparticles encapsulated in nitrogen-doped carbon nanosheets (Ni@NC-T) via a solvothermal polymerization and pyrolysis process using a Ni-hexamine coordination framework (NiHMT) as a precursor. The Ni@NC-900 catalyst exhibits superior ORR and OER activity under alkaline conditions, with an ORR performance (half-wave potential = 0.86 V) comparable to commercial Pt/C and an OER overpotential of only 430 mV at 10 mA cm⁻². Structural analysis indicates that the hierarchical porous structure and high specific surface area (409 m² g⁻¹) of Ni@NC-900 facilitate the exposure of active sites and enhance mass transport. The surface-doped nitrogen species, predominantly in the form of pyridinic N and graphitic N, promote electron transfer during the ORR. Furthermore, its application as a bifunctional cathode in rechargeable zinc-air batteries results in a high power density of 137 mW cm⁻², surpassing the performance levels of many existing carbon-based bifunctional catalysts. This work highlights a facile strategy for the fabrication of transition metal-based catalysts encapsulated in MOF-derived carbon matrices, with promising potential for energy storage and conversion devices. Full article

18 pages, 1516 KiB

Open AccessArticle

Hydrogen Yield from the Partial Oxidation of Methane: Effect of Sc Promoter on Supported Ni/MCM-41 Catalyst

by Ahmed A. Ibrahim, Omer A. Bellahwel, Fayez M. Al-Alweet, Mabrook S. Amer, Anis H. Fakeeha, Ahmed E. Abasaeed, Abdulaziz S. Bentalib and Ahmed S. Al-Fatesh

Catalysts 2025, 15(4), 337; https://doi.org/10.3390/catal15040337 (registering DOI) - 31 Mar 2025

Abstract

This study explores the impact of scandium (Sc) as a promoter on the catalytic performance of 4Ni/MCM-41 catalysts for the partial oxidation of methane (POM). 4Ni+Sc/MCM-41 catalysts were synthesized with varying Sc loadings of 0, 0.2, 0.4, 0.6, and 0.8 wt.%. These catalysts [...] Read more.

This study explores the impact of scandium (Sc) as a promoter on the catalytic performance of 4Ni/MCM-41 catalysts for the partial oxidation of methane (POM). 4Ni+Sc/MCM-41 catalysts were synthesized with varying Sc loadings of 0, 0.2, 0.4, 0.6, and 0.8 wt.%. These catalysts were characterized using several techniques, including N₂ physisorption, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), Raman spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). All catalysts exhibited a mesoporous structure characterized by narrow slit-shaped pores. Among them, the 4Ni+0.2Sc/MCM-41 catalyst showed the most consistent pore size distribution. The addition of Sc (scandium) facilitated the formation of strongly interacting nickel species, which enhanced the initial catalytic activity. However, a trade-off was observed between initial activity and long-term stability. The optimal Sc loading was determined to be 0.2 wt.%. This catalyst achieved the highest methane conversion rate of 63.9%, a hydrogen yield of 60%, and an H₂/CO ratio of 2.7 while also demonstrating superior stability during extended operation. The 4Ni+0.2Sc/MCM-41 catalyst showed only a 7% weight loss in the thermogravimetric analysis (TGA), which shows that it will stay stable even after being used for a long time. The improved performance of the Sc-promoted catalysts is attributable to the increased availability of active sites, enhanced stability, and better dispersion of nickel. These efforts aim to create more sustainable and efficient methods for hydrogen production, minimizing the negative effects associated with traditional processes. By advancing these technologies, we can further support the transition to a cleaner energy future. Full article

(This article belongs to the Section Industrial Catalysis)

37 pages, 31186 KiB

Open AccessReview

Application of Graphene-Based Solar Driven Interfacial Evaporation-Coupled Photocatalysis in Water Treatment

by Yining Zhang, Huiqin Wang and Jisheng Zhang

Catalysts 2025, 15(4), 336; https://doi.org/10.3390/catal15040336 (registering DOI) - 31 Mar 2025

Abstract

The global shortage of freshwater resources and the energy crisis have propelled solar-driven interfacial evaporation (SDIE) coupled with photocatalytic technology to become a research focus in efficient and low-carbon water treatment. Graphene-based materials demonstrate unique advantages in SDIE–photocatalysis integrated systems, owing to their [...] Read more.

The global shortage of freshwater resources and the energy crisis have propelled solar-driven interfacial evaporation (SDIE) coupled with photocatalytic technology to become a research focus in efficient and low-carbon water treatment. Graphene-based materials demonstrate unique advantages in SDIE–photocatalysis integrated systems, owing to their broadband light absorption, ultrafast thermal carrier dynamics, tunable electronic structure, and low evaporation enthalpy characteristics. This review systematically investigates the enhancement mechanisms of graphene photothermal conversion on photocatalytic processes, including (1) improving light absorption through surface morphology modulation, defect engineering, and plasmonic material compositing; (2) reducing water evaporation enthalpy via hydrophilic functional group modification and porous structure design; (3) suppressing heat loss through thermal insulation layers and 3D structural optimization; and (4) enhancing water transport efficiency via fluid channel engineering and wettability control. Furthermore, salt resistance strategies and structural optimization significantly improve system practicality and stability. In water treatment applications, graphene-based SDIE systems achieve synergistic “adsorption–catalysis–evaporation” effects, enabling efficient the degradation of organic pollutants, reduction in/fixation of heavy metal ions, and microbial inactivation. However, practical implementation still faces challenges including low steam condensation efficiency, insufficient long-term material durability, and high scaling-up costs. Future research should prioritize enhancing heat and mass transfer in condensation systems, optimizing material environmental adaptability, and developing low-cost manufacturing processes to promote widespread application of graphene-based SDIE–photocatalysis integrated systems. Full article

(This article belongs to the Special Issue Mineral-Based Composite Catalytic Materials)

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17 pages, 2215 KiB

Open AccessArticle

Hydrocracking of Polyethylene to Gasoline-Range Hydrocarbons over a Ruthenium-Zeolite Bifunctional Catalyst System with Optimal Synergy of Metal and Acid Sites

by Qing Du, Xin Shang, Yangyang Yuan, Xiong Su and Yanqiang Huang

Catalysts 2025, 15(4), 335; https://doi.org/10.3390/catal15040335 (registering DOI) - 31 Mar 2025

Abstract

Chemical recycling of plastic waste, especially polyolefins, into valuable liquid fuels is of considerable significance to address the serious issues raised by their threat on environmental and human health. Nevertheless, the construction of efficient and economically viable catalytic systems remains a significant hurdle. [...] Read more.

Chemical recycling of plastic waste, especially polyolefins, into valuable liquid fuels is of considerable significance to address the serious issues raised by their threat on environmental and human health. Nevertheless, the construction of efficient and economically viable catalytic systems remains a significant hurdle. Herein, we developed an efficient bifunctional catalyst system comprising γ-Al₂O₃-supported ruthenium nanoparticles (Ru/γ-Al₂O₃) and β-zeolite for the conversion of polyolefins into gasoline-range hydrocarbons. A yield of C_5–12 paraffins up to 73.4% can be obtained with polyethene as the reactant at 250 °C in hydrogen. The Ru sites primarily activate the initial cleavage of C–H bonds of polymer towards the formation of olefin intermediates, which subsequently go through further cracking and isomerization over the acid sites in β-zeolite. Employing in situ infrared spectroscopy and probe–molecule model reactions, our investigation reveals that the optimized proportion and spatial distribution of the dual catalytic sites are pivotal in the tandem conversion process. This optimization synergistically regulates the cracking kinetics and accelerates intermediate transfer, thereby minimizing the production of side C_1–4 hydrocarbons resulting from over-cracking at the Ru sites and enhancing the yield of liquid fuels. This research contributes novel insights into catalyst design for the chemical upgrading of polyolefins into valuable chemicals, advancing the field of plastic waste recycling and sustainable chemical production. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection, 2nd Edition)

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24 pages, 6126 KiB

Open AccessFeature PaperArticle

Enhanced H₂ Production Efficiency in Photo-Reforming of PET Waste Plastic Using Dark-Deposited Atom/Nanocomposite Pt/TiO₂ Photocatalysts

by E. M. N. Thiloka Edirisooriya, Punhasa S. Senanayake, Pei Xu and Huiyao Wang

Catalysts 2025, 15(4), 334; https://doi.org/10.3390/catal15040334 - 31 Mar 2025

Abstract

Photo-reforming waste polyethylene terephthalate (PET) in alkaline aqueous solutions is a novel approach for green hydrogen production. This study focuses on improving the catalytic efficiency of Pt/TiO₂ for the photo-reforming of waste PET using an innovative dark deposition method to deposit Pt [...] Read more.

Photo-reforming waste polyethylene terephthalate (PET) in alkaline aqueous solutions is a novel approach for green hydrogen production. This study focuses on improving the catalytic efficiency of Pt/TiO₂ for the photo-reforming of waste PET using an innovative dark deposition method to deposit Pt single atoms on nano TiO₂ (Pt/TiO₂), thereby increasing the catalytic efficiency while reducing the cost of the catalyst. The precursor concentration was optimized to control the size and distribution of the Pt clusters/atoms, and the TiO₂ support was annealed at different temperatures to modify the properties of Pt/TiO₂. Nine Pt/TiO₂ catalysts were synthesized using different Pt precursor concentrations and annealing temperatures. The catalysts were characterized to measure their morphological, crystalline, and electronic properties, as well as their hydrogen yields via PET photo-reforming. The hydrogen conversion efficiency and external quantum yield (EQY) were calculated and compared with those of traditional direct-deposited catalysts. The correlation between the different characteristics of the dark-deposited and direct-deposited catalysts and their influence on the hydrogen yield in the photo-reforming process was statistically analyzed using principal component analysis. Catalysts deposited under dark conditions exhibited 5-fold and 7-fold enhancements in hydrogen conversion efficiency and EQY, respectively, compared to conventional catalytic systems. These findings indicate that the proposed catalytic system provides a viable solution for minimizing Pt loading, reducing the cost of the catalyst, and maintaining a higher hydrogen conversion efficiency. Full article

(This article belongs to the Special Issue Advances in Photocatalytic Degradation)

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23 pages, 3765 KiB

Open AccessArticle

Electro-Refinery in Organics to Produce Energy Carriers: Co-Generation of Green Hydrogen and Carboxylic Acids by Glycerol Electrooxidation Using Dimensionally Stable Anode

by Letícia M. G. da Silva, Letícia G. A. Costa, José E. L. Santos, Emily C. T. de A. Costa, Aruzza M. de Morais Araújo, Amanda D. Gondim, Lívia N. Cavalcanti, Marco A. Quiroz, Elisama V. dos Santos and Carlos A. Martínez-Huitle

Catalysts 2025, 15(4), 333; https://doi.org/10.3390/catal15040333 - 31 Mar 2025

Abstract

The urgency to decarbonize fuels has contributed to a rise in biofuel production, which has culminated in a significant increase in the waste quantity of glycerol produced. Therefore, to convert glycerol waste into high-value products, electrochemical oxidation (EO) is a viable alternative for [...] Read more.

The urgency to decarbonize fuels has contributed to a rise in biofuel production, which has culminated in a significant increase in the waste quantity of glycerol produced. Therefore, to convert glycerol waste into high-value products, electrochemical oxidation (EO) is a viable alternative for the co-generation of carboxylic acids, such as formic acid (FA) and green hydrogen (H₂), which are considered energy carriers. The aim of this study is the electroconversion of glycerol into FA by EO using a divided electrochemical cell, driven by a photovoltaic (PV) system, with a dimensionally stable anode (DSA, Ti/TiO₂-RuO₂-IrO₂) electrode as an anode and Ni-Fe stainless steel (SS) mesh as a cathode. To optimize the experimental conditions, studies were carried out evaluating the effects of applied current density (j), electrolyte concentration, electrolysis time, and electrochemical cell configuration (undivided and divided). According to the results, the optimum experimental conditions were achieved at 90 mA cm⁻², 0.1 mol L⁻¹ of Na₂SO₄ as a supporting electrolyte, and 480 min of electrolysis. In this condition, 256.21 and 211.17 mg L⁻¹ of FA were obtained for the undivided and divided cells, respectively, while the co-generation of 6.77 L of dry H₂ was achieved in the divided cell. The electroconversion process under the optimum conditions was also carried out with a real sample, where organic acids like formic and acetic acids were co-produced simultaneously with green H₂. Based on the preliminary economic analysis, the integrated-hybrid process is an economically viable and promising alternative when it is integrated with renewable energy sources such as solar energy. Full article

(This article belongs to the Special Issue Photocatalyzed and Electrochemical Processes for a Cleaner Environment)

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4 pages, 152 KiB

Open AccessEditorial

Catalytic Reforming and Hydrogen Production: From the Past to the Future

by Georgios Bampos, Paraskevi Panagiotopoulou and Eleni A. Kyriakidou

Catalysts 2025, 15(4), 332; https://doi.org/10.3390/catal15040332 - 31 Mar 2025

Abstract

Continuously increasing energy demands and the intense environmental pollution caused by the increasing global population and modern lifestyles have driven research interest toward finding alternative sustainable energy sources [...] Full article

(This article belongs to the Special Issue Catalytic Reforming and Hydrogen Production: From the Past to the Future)

14 pages, 3454 KiB

Open AccessFeature PaperArticle

Synthesis of Star Isotactic Polypropylene via Styryldichlorosilane/Hydrogen Consecutive Chain Transfer Reaction

by Naw Jar, Fengtao Chen and Jin-Yong Dong

Catalysts 2025, 15(4), 331; https://doi.org/10.3390/catal15040331 - 31 Mar 2025

Abstract

This paper elucidates the consecutive chain transfer reaction, initially to (p-vinylphenyl) methyl dichlorosilane (or (p-vinylbenzyl) methyl dichlorosilane), followed by hydrogen, during metallocene-catalyzed propylene polymerization by an isospecific metallocene catalyst (i.e., rac-dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride, I)/ activated with methylaluminoxane (MAO), rendering [...] Read more.

This paper elucidates the consecutive chain transfer reaction, initially to (p-vinylphenyl) methyl dichlorosilane (or (p-vinylbenzyl) methyl dichlorosilane), followed by hydrogen, during metallocene-catalyzed propylene polymerization by an isospecific metallocene catalyst (i.e., rac-dimethylsilylbis(2-methyl-4-phenylindenyl)zirconium dichloride, I)/ activated with methylaluminoxane (MAO), rendering a catalytic access styryldichlorosilane capped isotactic polypropylenes (iPP). The PP molecular weight is inversely related to the molar ratio of [(p-vinylphenyl) methyl dichlorosilane]/[propylene] and [(p-vinylbenzyl) methyl dichlorosilane]/[propylene]. Every polypropylene chain formed presents a terminal (p-vinylphenyl) methyl dichlorosilane (or (p-vinylbenzyl) methyl dichlorosilane) unit. Hydrogen enhances the concentration of the starting arm polymer for the subsequent synthesis of the star polymer by increasing the incorporation of the chain terminal group. In order to create star polymers with isotactic polypropylene(iPP) as the arm and a siloxane cross-linking structure as the core, the terminal dichlorosilane iPP unit can work up (with water) to create cyclic siloxane oligomer interlinkages between iPP chains. Full article

(This article belongs to the Section Catalysis in Organic and Polymer Chemistry)

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22 pages, 4029 KiB

Open AccessFeature PaperArticle

Hydrogen Responses of Propylene Polymerization with MgCl₂-Supported Ziegler–Natta Catalysts in the Presence of Different Silane External Donors

by Xiaoyu Liu, Biao Zhang, Wenqi Guo, Baiyu Jiang, Miao Du, Zhisheng Fu and Zhiqiang Fan

Catalysts 2025, 15(4), 330; https://doi.org/10.3390/catal15040330 - 31 Mar 2025

Abstract

External donor (De) modification is an effective way to enhance the stereoselectivity of propylene polymerization with supported Ziegler–Natta catalysts. Aminosilane as a novel type of external donor has been found to have the excellent ability of enhancing the isoselectivity of propylene polymerization. In [...] Read more.

External donor (De) modification is an effective way to enhance the stereoselectivity of propylene polymerization with supported Ziegler–Natta catalysts. Aminosilane as a novel type of external donor has been found to have the excellent ability of enhancing the isoselectivity of propylene polymerization. In this work, dipiperidyldimethoxysilane (Donor-Py) was compared with cyclohexyl(methyl)dimethoxysilane (Donor-C) and dicyclopentyldimethoxysilane (Donor-D) for propylene polymerization in the presence or absence of hydrogen. By analyzing the effects of external donors on catalytic activity, polymer chain structures and their distributions, and the number and reactivity of three groups of active centers with different stereoselectivities, the performance of each De in enhancing stereoselectivity was compared. Propylene polymerization in the presence of RSi(OR’)₃-type De (R = n-propyl or i-butyl, R’ = methyl or ethyl) and hydrogen was also studied. Donor-Py produced PP with higher molecular weight and was more sensitive to hydrogen than Donor-D. According to the fractionation results, Donor-Py produced PP with the lowest content of medium-isotactic PP and the highest content of highly isotactic PP, especially at high hydrogen concentrations. By raising hydrogen concentrations, the number of active centers was enhanced in systems with Donor-C and Donor-D while it was reduced when Donor-Py was added. When Donor-Py was used as De, the effects of H₂ concentration on active center distributions and the reactivity of different active centers were evidently different from those of Donor-C and Donor-D. Donor-Py showed the best performance among the De used in this work in producing PP with both high isotacticity and good processability. The mechanism of De effects and hydrogen effects is discussed based on the results of polymerization kinetics and PP chain structures. Full article

(This article belongs to the Section Catalysis in Organic and Polymer Chemistry)

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20 pages, 4474 KiB

Open AccessArticle

Revisiting the Impact of CO₂ on the Activity and Selectivity of Cobalt-Based Catalysts for Fischer–Tropsch Synthesis Under Industrial-Relevant Conditions

by Zhiyu Chen, Jinbo Du, Denghui Chen, Fuqing Gong, Yang Gao, Zhen Huang, De Chen and Jia Yang

Catalysts 2025, 15(4), 329; https://doi.org/10.3390/catal15040329 - 31 Mar 2025

Abstract

Understanding the impact of CO₂ on cobalt-based Fischer–Tropsch synthesis catalysts is critical for optimizing system efficiency, particularly in scenarios employing solid oxide electrolysis cells for syngas production, given the inevitable incorporation of CO₂ into syngas during the SOEC co-electrolysis process. In [...] Read more.

Understanding the impact of CO₂ on cobalt-based Fischer–Tropsch synthesis catalysts is critical for optimizing system efficiency, particularly in scenarios employing solid oxide electrolysis cells for syngas production, given the inevitable incorporation of CO₂ into syngas during the SOEC co-electrolysis process. In this study, we conducted comparative experiments using a Co-Re/γ-Al₂O₃ catalyst in a fixed-bed reactor under industrial conditions (2 MPa, 493 K, GHSV = 6000–8000 Ncm³/g_cat/h), varying the feed gas compositions of H₂, CO, CO₂, and Ar. At an H₂/CO ratio of 2, the addition of CO₂ led to a progressive decline in catalyst performance, attributed to carbon deposition and cobalt carbide formation, as confirmed by Raman spectroscopy, XRD analyses, and TPH. Furthermore, DFT calculations combined with ab initio atomistic thermodynamics (AIAT) were performed to gain molecular insights into the loss of catalyst activity arising from multiple factors, including (sub)surface carbon derived from CO or CO₂, polymeric carbon, and carbide formation. Full article

(This article belongs to the Section Catalysis for Sustainable Energy)

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30 pages, 5082 KiB

Open AccessReview

Recent Advances in Cu-Based Metal–Organic Framework Electrocatalysts for CO₂ Reduction Reactions

by Honglin Gao, Ting Yang, Wen Nie, Yuefeng Gao, Zhen Wang and Aiyi Dong

Catalysts 2025, 15(4), 328; https://doi.org/10.3390/catal15040328 - 30 Mar 2025

Abstract

The electrochemical reduction of carbon dioxide (CO₂RR) utilizing intermittent electricity from renewable energy sources represents an emerging and promising approach to achieve carbon neutrality and mitigate the greenhouse effect. This review comprehensively summarizes recent advances in Cu-based metal–organic framework (MOF) electrocatalysts [...] Read more.

The electrochemical reduction of carbon dioxide (CO₂RR) utilizing intermittent electricity from renewable energy sources represents an emerging and promising approach to achieve carbon neutrality and mitigate the greenhouse effect. This review comprehensively summarizes recent advances in Cu-based metal–organic framework (MOF) electrocatalysts for CO₂RR, focusing on their applications in producing C₁ and C₂₊ products. This paper highlights key strategies such as nanostructure manipulation, multi-component tandem catalysis, single-atom alloying, and ligand functionalization to optimize the binding energies of intermediate species and promote selective CO₂RR pathways. Numerous examples are presented, showcasing remarkable Faradaic efficiencies and product selectivities achieved through rational catalyst design. Furthermore, the use of MOF-derived materials and composites with other materials, like carbon nanotubes, graphene, and metal oxides, is discussed to enhance conductivity, stability, and selectivity. Despite the significant progress, challenges remain in achieving stable and scalable catalysts with high activity and selectivity towards specific C₂₊ products. This review underscores the importance of precise control of catalyst composition, structure, and surface properties to tackle these challenges and provides valuable insights for future research directions in developing advanced Cu-based MOF electrocatalysts for practical applications in CO₂ conversion technologies. Full article

13 pages, 2744 KiB

Open AccessArticle

Study of Biochar with Different Cellulose/Lignin Ratios for Organic Pollutant Removal in Water Through Fenton-like Catalysis Assisted with Adsorption

by Xinyan Yu, Wanting Xu and Lu Gan

Catalysts 2025, 15(4), 327; https://doi.org/10.3390/catal15040327 - 29 Mar 2025

Abstract

In the present study, cellulose and lignin with different weight ratios were mixed and pyrolyzed to prepare biochars for organic dye pollutant removal in water via Fenton-like catalysis. The results indicated that a higher cellulose content in a biomass precursor could result in [...] Read more.

In the present study, cellulose and lignin with different weight ratios were mixed and pyrolyzed to prepare biochars for organic dye pollutant removal in water via Fenton-like catalysis. The results indicated that a higher cellulose content in a biomass precursor could result in a lower biochar yield with a lower carbon content in the biochar. Moreover, with the increase in cellulose content, the resulting biochar had a higher graphitization degree with higher levels of crystallinity, as well as a richer porosity. When using Rhodamine B (RhB) as the dye probe, the biochar derived from a higher cellulose/lignin ratio precursor exhibited better adsorptive performance. It was further found that the biochar could act as a Fenton-like catalyst to activate peroxydisulfate (PDS) and accelerate RhB removal via a degradation route, in which single oxygen (¹O₂) was identified as the active species. Therefore, the biochar/PDS catalytic system exhibited prominent RhB removal stability in various water matrices with a wide pH application range. This study develops a new approach to prepare biomass-derived biochar with high organic removal capacity via Fenton-like catalysis assisted with adsorption synergy. Full article

(This article belongs to the Special Issue State-of-the-Art Catalytic Conversion of Biomass and Their Derivatives in Asia)

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12 pages, 2563 KiB

Open AccessFeature PaperArticle

Study on the Immobilization of a Transaminase Biocatalyst for the Synthesis of Sitagliptin

by Chiara Rosati, Oreste Piccolo and Antonella Petri

Catalysts 2025, 15(4), 326; https://doi.org/10.3390/catal15040326 - 28 Mar 2025

Abstract

Sitagliptin, an important anti-diabetic drug, can be obtained using transaminase (TA) enzymes, which are known to be promising biocatalysts for the production of highly enantiopure amines under mild reaction conditions. In an industrial context, the use of immobilized enzymes can provide several advantages, [...] Read more.

Sitagliptin, an important anti-diabetic drug, can be obtained using transaminase (TA) enzymes, which are known to be promising biocatalysts for the production of highly enantiopure amines under mild reaction conditions. In an industrial context, the use of immobilized enzymes can provide several advantages, such as the improved stability of the biocatalyst and easy product recovery. In this study, a new commercially available transaminase enzyme to produce sitagliptin was immobilized on inorganic and organic supports using two different approaches: adsorption and covalent bond formation. Among the inorganic media, non-functionalized silica gel was chosen for its stability and competitive cost. A range of commercially available resins with different functionalities have also been selected for their characteristics that can meet industrial standards. The immobilized biocatalysts were first tested in the transamination of acetophenone as a model substrate, which obtains, in most cases, higher conversions with respect to soluble enzymes. The best results in the enantioselective synthesis of sitagliptin were achieved with the sample immobilized on the epoxy- and octadecyl-functionalized methacrylic resin, which allowed the complete conversion of the corresponding ketone and high enantioselectivity (>99% ee). Moreover, the recycling of the supported enzyme could be performed in a continuous flow system without loss of activity for five consecutive runs. Full article

(This article belongs to the Special Issue Recent Advances in Biocatalysis and Enzyme Engineering)

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16 pages, 8102 KiB

Open AccessArticle

Co-Production of Furfural, Xylo-Oligosaccharides, and Reducing Sugars from Waste Yellow Bamboo Through the Solid Acid-Assisted Hydrothermal Pretreatment

by Dan Yang, Qizhen Yang, Ruiqing Yang, Yifeng Zhou and Yucai He

Catalysts 2025, 15(4), 325; https://doi.org/10.3390/catal15040325 - 28 Mar 2025

Abstract

Lignocellulosic waste biomass, a versatile natural resource derived from plants, has gained significant attention for its potential in the sustainable production of biobased chemicals. Furfural (FAL), xylo-oligosaccharides (XOSs), and reducing sugars are important platform chemicals, which can be obtained through the valorization of [...] Read more.

Lignocellulosic waste biomass, a versatile natural resource derived from plants, has gained significant attention for its potential in the sustainable production of biobased chemicals. Furfural (FAL), xylo-oligosaccharides (XOSs), and reducing sugars are important platform chemicals, which can be obtained through the valorization of lignocellulosic solid biomass in a green and sustainable way. Waste yellow bamboo (YB) is one kind of abundant, inexpensive, and renewable lignocellulosic biomass resource. In order to improve the high-value utilization rate of raw YB, biochar-based solid acid catalyst (AT-Sn-YB) was utilized to assist the hydrothermal pretreatment for the valorization of YB in water. Under the optimal reaction conditions (200 °C, 60 min, and AT-Sn-YB dosage of 5.4 wt%), the FAL yield reached 60.8%, and 2.5 g/L of XOSs was obtained in the pretreatment system. It was observed that the surface structure of YB became rough and loose, exposing a significant number of pores. The accessibility increased from 101.8 mg/g to 352.6 mg/g after combined treatment. The surface area and hydrophobicity of lignin were 70.7 m²/g and 2.5 L/g, respectively, which were significantly lower than those of untreated YB (195.4 m²/g and 4.1 L/g, respectively). The YB solid residues obtained after treatment were subjected to enzymatic saccharification, achieving an enzymatic hydrolysis efficiency of 47.9%. Therefore, the hydrothermal pretreatment assisted by the AT-Sn-YB catalyst shows potential application value in FAL production and bamboo utilization, providing important references for other biomass materials. Full article

(This article belongs to the Special Issue Waste-to-Resources Through Catalysis in Green and Sustainable Way)

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17 pages, 5897 KiB

Open AccessArticle

MOF-808 as Effective Support for Cu-Based Catalyst for CO₂ Hydrogenation to Methanol

by Abinavnataraj Ramakrishnan, Simmy Rathod, Wakshum Mekonnen Tucho, Sachin M. Chavan and Zhixin Yu

Catalysts 2025, 15(4), 324; https://doi.org/10.3390/catal15040324 - 28 Mar 2025

Abstract

The thermocatalytic hydrogenation of CO₂ to methanol offers a promising route for reducing greenhouse gas emissions (GHG) and producing valuable chemicals and fuels. In this study, copper–zinc bimetallic catalysts supported on a zirconium-based MOF-808 framework were synthesized via a facile deposition–precipitation method [...] Read more.

The thermocatalytic hydrogenation of CO₂ to methanol offers a promising route for reducing greenhouse gas emissions (GHG) and producing valuable chemicals and fuels. In this study, copper–zinc bimetallic catalysts supported on a zirconium-based MOF-808 framework were synthesized via a facile deposition–precipitation method and compared to a conventional Cu/ZnO/Al₂O₃ (CZA) catalyst. MOF-808 was selected due to its high surface area and porous structure, which enhance metal dispersion. Characterization through X-ray diffraction (XRD) and N₂ physisorption showed significant changes in surface area and pore structure after Cu-Zn incorporation and calcination. The 50-CuZn MOF-808 catalyst achieved the best catalytic performance at 260 °C and 40 bar, demonstrating a high STY of 193.32 gMeOH·Kgcat⁻¹ h⁻¹ and a turnover frequency (TOF) of 47.44 h⁻¹, surpassing traditional CZA catalysts. The strong Cu-Zn-Zr interactions within the MOF-808 framework played a crucial role in promoting CO₂ activation and methanol formation. This study underscores the potential of MOF-808-supported Cu-Zn catalysts as viable alternatives to traditional systems for CO₂ hydrogenation to methanol. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion, 2nd Edition)

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24 pages, 3246 KiB

Open AccessFeature PaperArticle

Layered Double Hydroxide (LDH)-Derived Mixed Oxides for Enhanced Light Hydrocarbon Production from CO₂ Hydrogenation

by Evridiki Mandela, Antigoni G. Margellou, Athanasia Kotsaridou, George E. Marnellos, Michalis Konsolakis and Konstantinos S. Triantafyllidis

Catalysts 2025, 15(4), 323; https://doi.org/10.3390/catal15040323 - 27 Mar 2025

Abstract

Layered double hydroxide (LDH)-derived mixed oxides offer a promising approach for CO₂ hydrogenation to light hydrocarbons. Herein, we explore the impact of various transition metals (X = Mn, Co, Cu, and Zn) incorporated into the M-Al or M-(Al+Fe) LDH structures, with the [...] Read more.

Layered double hydroxide (LDH)-derived mixed oxides offer a promising approach for CO₂ hydrogenation to light hydrocarbons. Herein, we explore the impact of various transition metals (X = Mn, Co, Cu, and Zn) incorporated into the M-Al or M-(Al+Fe) LDH structures, with the aim of exploring possible synergistic effects. Structural and compositional analyses reveal that an abundance of Fe over Al (Fe/Al ratio ~4) leads to the formation of mixed oxide crystalline phases attributed to CoFe₂O₄, CuFe₂O₄, and ZnFe₂O₄. Catalytic evaluation results demonstrate that the X-Al LDH-derived oxides exhibit high CO₂ conversion yet are selective to CH₄ or CO. In contrast, Fe incorporation shifts selectivity toward higher hydrocarbons. Specifically, the yield to higher hydrocarbons (C₂⁺) follows the order Ζn-Al-Fe > Cu-Al-Fe > Mn-Al-Fe > Co-Al-Fe >> Mn-Al, Co-Al, Zn-Al, Cu-Al, highlighting the pivotal role of Fe. Moreover, Zn-Al-Fe and Mn-Al-Fe catalysts have been shown to be the most selective towards light olefins. Zn-based systems also exhibit high thermal and structural stability with minimal coke formation, whereas Co-, Cu-, and Mn-based catalysts, when modified with Fe, experience increased carbon deposition or structural changes that may impact long-term stability. This work provides insights into the combined role of Fe and a second transition metal in LDHs for modulating catalytic activity, phase transformations, and stability, underscoring the need for further optimization to balance selectivity and catalyst durability in CO₂ hydrogenation applications. Full article

(This article belongs to the Collection Layered Double Hydroxides and Related Materials for Advanced Heterogeneous Catalytic Processes)

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16 pages, 6203 KiB

Open AccessArticle

Application of Clay-Based Catalysts in Co-Conversion and Co-Pyrolysis of Chlorella and Oil Shale

by Xianglong Meng, Ranran Song and Junjie Bian

Catalysts 2025, 15(4), 322; https://doi.org/10.3390/catal15040322 - 27 Mar 2025

Abstract

In this study, natural clay-like silicate minerals were used as precursors to prepare highly acid-catalytic hydrophobic catalysts. A series of sulfonic acid-functionalized attapulgite catalysts, SO₃H-APG, were fabricated by the ball-milling–oxidation method. The catalytic performance in the co-liquefaction and co-pyrolysis of Chlorella [...] Read more.

In this study, natural clay-like silicate minerals were used as precursors to prepare highly acid-catalytic hydrophobic catalysts. A series of sulfonic acid-functionalized attapulgite catalysts, SO₃H-APG, were fabricated by the ball-milling–oxidation method. The catalytic performance in the co-liquefaction and co-pyrolysis of Chlorella and oil shale was investigated. The catalysts were analyzed using hydrophobicity evaluation, TEM, BET, FTIR, and other characterization methods. The SO₃H-APG catalysts exhibited good hydrophobicity and dispensability. Sulfonation grafting improved their excellent hydrocarbon conversion activity. According to the GC–MS results, the addition of the SO₃H-APG catalysts shifted the co-liquefaction products of microalgae and oil shale towards lower carbon numbers, with the majority of the products concentrated between C5 and C12, and a content of 84.9% in the range of C5–C11, while the content of products in the range of C12–C20 was only 15.1%. In the co-pyrolysis experiments, the addition of the catalysts promoted the thermal decomposition reaction. The synergistic effect between oil shale and microalgae facilitated the production of more hydrocarbon compounds with a higher H/C atomic ratio. The development of this type of catalyst provides an economically favorable approach for the co-conversion of algae and oil shale. The oil shale pyrolysis kinetic diagram shows that adding the APG clay-based catalyst significantly reduces the time for achieving the same conversion rate, especially below 300 °C, where the in situ catalytic effect is most pronounced. Full article

(This article belongs to the Special Issue Biomass Catalytic Conversion to Value-Added Chemicals)

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15 pages, 2176 KiB

Open AccessFeature PaperArticle

A Promising Monolithic Catalyst for Advanced VOCs Oxidation by Graphene-Doped α-MnO₂ Loaded on Cordierite Honeycomb

by Yilin Dong, Yiyang Zhao, Jing Sun, Yafang Shen, Xiqiang Zhao, Wenlong Wang, Zhanlong Song and Yanpeng Mao

Catalysts 2025, 15(4), 321; https://doi.org/10.3390/catal15040321 - 27 Mar 2025

Abstract

A high-activity, low-cost, and easy-to-prepare monolithic catalyst is crucial for the industrial catalytic combustion of volatile organic compounds (VOCs) in a cost-effective manner. In this study, a highly efficient monolithic catalyst, designated as 4GM/COR, was developed by loading 4% graphene-doped α-MnO₂ (4GM) [...] Read more.

A high-activity, low-cost, and easy-to-prepare monolithic catalyst is crucial for the industrial catalytic combustion of volatile organic compounds (VOCs) in a cost-effective manner. In this study, a highly efficient monolithic catalyst, designated as 4GM/COR, was developed by loading 4% graphene-doped α-MnO₂ (4GM) catalyst onto pre-etched cordierite (COR) blocks using a straightforward “ball-milling-assisted impregnation” method. The anchoring force of the cordierite pores, generated through oxalic acid etching, enables the uniform and robust loading of powdered 4GM onto COR, preventing detachment under high temperatures or high gas flow rates. The loading rate, specific surface area, and concentrations of Mn³⁺ and surface-lattice and absorbed oxygen species in the monolithic catalyst increase with impregnation times from 2 to 4, indicating that catalytic activity is optimized through repeated impregnation. Catalytic performance tests demonstrated that the 4-4GM/COR exhibited the highest activity, achieving 90% degradation of toluene at 200 °C under both dry and humid (relative humidity is 85%) conditions. Furthermore, the 4-4GM/COR maintains high catalytic stability and activity even at a large GHSV of 6000 h⁻¹. To conclude, the 4-4GM/COR monolithic catalyst developed in this study not only represents a promising option for industrial applications but also serves as an important reference for the synthesis of monolithic catalysts. Full article

(This article belongs to the Special Issue Catalytic Removal of Volatile Organic Compounds (VOCs))

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