Catalysts

14 pages, 4880 KiB

Open AccessArticle

Enhancement Study of the Photoactivity of TiO₂ Photocatalysts during the Increase of the WO₃ Ratio in the Presence of Ag Metal

by Sharah H. Aldirham, Ahmed Helal, Mohd Shkir, M. A. Sayed and Atif Mossad Ali

Catalysts 2024, 14(9), 633; https://doi.org/10.3390/catal14090633 (registering DOI) - 18 Sep 2024

Abstract

Nanocomposites (NCs) consisting of 4%Ag/x%WO₃/TiO₂, with varied concentrations (x = 1, 3, 5, 7 wt.%) of WO₃, were successfully synthesized using the sol-gel process to examine their photocatalytic performance. The synthesized 4%Ag/x%WO [...] Read more.

Nanocomposites (NCs) consisting of 4%Ag/x%WO₃/TiO₂, with varied concentrations (x = 1, 3, 5, 7 wt.%) of WO₃, were successfully synthesized using the sol-gel process to examine their photocatalytic performance. The synthesized 4%Ag/x%WO₃/TiO₂ nanopowder was characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectra (UV–vis DRS), photoluminescence (PL), and Brunauer–Emmett–Teller (BET) surface area analysis to elucidate its physicochemical properties. The photocatalytic evaluation revealed that the Ag/1%WO₃/TiO₂ nanocomposite exhibits 98% photoreduction efficiency for Cr(VI) after 2 h under visible light due to the impact of the plasmonic effect of Ag atoms. In addition, the Ag/4%WO₃/TiO₂ shows about 95% photooxidation efficiency for methylene blue (MB) dye after 4 h. Full article

(This article belongs to the Special Issue Cutting-Edge Photocatalysis)

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14 pages, 2131 KiB

Open AccessArticle

Influence of Current Collector Design and Combination on the Performance of Passive Direct Methanol Fuel Cells

by Weibin Yu, Zhiyuan Xiao, Weiqi Zhang, Qiang Ma, Zhuo Li, Xiaohui Yan, Huaneng Su, Lei Xing and Qian Xu

Catalysts 2024, 14(9), 632; https://doi.org/10.3390/catal14090632 - 18 Sep 2024

Abstract

In this work, an anode current collector with a scaled step-hole structure (called SF-type) and a cathode current collector with a perforated cross-tilt structure (called X-type) were designed and fabricated for application in passive direct methanol fuel cells (DMFCs). A whole-cell test showed [...] Read more.

In this work, an anode current collector with a scaled step-hole structure (called SF-type) and a cathode current collector with a perforated cross-tilt structure (called X-type) were designed and fabricated for application in passive direct methanol fuel cells (DMFCs). A whole-cell test showed that the combination of an anode SF-type current collector and cathode conventional current collector increased the optimal methanol concentration from 6 M to 8 M and the maximum power density to 5.40 mW cm⁻², which improved the cell performance by 51.6% compared to that of the conventional design under ambient testing conditions. The combination of the anode conventional current collector and cathode X-type current collector achieved a maximum power density of 5.65 mW cm⁻² with a 58.7% performance improvement, while the optimal methanol concentration was increased to 10 M. Furthermore, the combination of anode SF-type and cathode X-type obtained the highest power density at 6.22 mW cm⁻². Notably, the anode and cathode catalyst loadings used in this study were 2.0 mg cm⁻², which is lower than the commonly used loading, thus reducing the fuel cell cost. Full article

(This article belongs to the Special Issue Advances in Catalyst Design and Application for Fuel Cells)

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18 pages, 5608 KiB

Open AccessArticle

Production of Bio-Oil from Sugarcane Bagasse through Hydrothermal Liquefaction Processes with Modified Zeolite Socony Mobil-5 Catalyst

by Thandiswa Jideani, Ntalane Sello Seroka and Lindiwe Khotseng

Catalysts 2024, 14(9), 631; https://doi.org/10.3390/catal14090631 - 18 Sep 2024

Abstract

In response to the increasing global demand for sustainable energy alternatives, this research explores the efficient conversion of sugarcane bagasse to bio-oil through hydrothermal liquefaction (HTL) processes with modified Zeolite Socony Mobil-5 catalysts (ZSM-5). The study systematically investigates the impact of feedstock quantity, [...] Read more.

In response to the increasing global demand for sustainable energy alternatives, this research explores the efficient conversion of sugarcane bagasse to bio-oil through hydrothermal liquefaction (HTL) processes with modified Zeolite Socony Mobil-5 catalysts (ZSM-5). The study systematically investigates the impact of feedstock quantity, reaction temperature, duration, and catalyst loading on bio-oil yield and quality. Optimisation experiments revealed that a feedstock amount of 10 grammes, an HTL temperature of 340 °C for 60 min and a ZSM-5 catalyst loading of 3 grammes resulted in the highest bio-oil yield. Furthermore, the introduction of Ni and Fe metals to ZSM-5 exhibited enhanced catalytic activity without compromising the structure of the zeolites. Comprehensive characterisation of modified catalysts using SEM-EDS, XRD, TGA, TEM, and FTIR provided insight into their structural and chemical properties. The successful incorporation of Ni and Fe into ZSM-5 was confirmed, highlighting promising applications in hydrothermal liquefaction. Gas chromatography–mass spectrometry (GC-MS) analysis of bio-oils demonstrated the effectiveness of the 2% Fe/ZSM-5 catalyst, highlighting a significant increase in hydrocarbon content. FTIR analysis of the produced bio-oils indicated a reduction in functional groups and intensified aromatic peaks, suggesting a shift in chemical composition favouring aromatic hydrocarbons. This study provides valuable information on HTL optimisation, catalyst modification, and bio-oil characterisation, advancing the understanding of sustainable biofuel production. The findings underscore the catalytic prowess of modified ZSM-5, particularly with iron incorporation, in promoting the formation of valuable hydrocarbons during hydrothermal liquefaction. Full article

(This article belongs to the Section Catalytic Reaction Engineering)

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14 pages, 4307 KiB

Open AccessArticle

PEDOT: PSS Doped Activated Biochar as a Novel Composite Material for Photocatalytic and Efficient Energy Storage Application

by Taymour A. Hamdalla, Saleh A. Al-Ghamdi, Shahd Alfadhli, Abdulrhman M. Alsharari, M. Chiesa and Syed Khasim

Catalysts 2024, 14(9), 630; https://doi.org/10.3390/catal14090630 - 18 Sep 2024

Abstract

Herein, we report the synthesis of activated biochar from green algae and the effect of its doping on the structural, photocatalytic, and energy storage properties of PEDOT-PSS. The morphology of pure and doped samples was investigated with Fourier Transform Infrared Spectroscopy (FTIR), Atomic [...] Read more.

Herein, we report the synthesis of activated biochar from green algae and the effect of its doping on the structural, photocatalytic, and energy storage properties of PEDOT-PSS. The morphology of pure and doped samples was investigated with Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, and thermogravimetric analysis (TGA). AFM results for PEDOT-PSS@6wt.% of BC indicate that the calculated average peak height, particle size, and roughness were 283 nm, 136 nm, and 71 nm, respectively. Adding biochar to PEDOT-PSS significantly improved the thermal stability of PEDOT-PSS up to 550 °C. The novel photocatalyst PEDOT-PSS@6wt.% BC improved photocatalytic performance by approximately 17% in Methylene Blue (MB) dye removal. The electrochemical performance in terms of supercapacitors for the synthesized samples was investigated using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), specific capacitance, stability, and electrochemical impedance spectra (EIS). PEDOT-PSS@6wt.% of BC as a novel electrode material in supercapacitors exhibits an initial specific capacitance of 1300 Fg⁻¹. Moreover, the PEDOT-PSS@6wt.% of BC electrode shows excellent stability up to 1000 cycles of operation. The EIS studies suggest the presence of charge transfer resistance. Considering the economical biosynthesis and multifunctional features, the PEDOT-PSS@6wt.% of BC could potentially be used as a photocatalyst to remove organic dyes and supercapacitors in energy storage applications. Full article

(This article belongs to the Special Issue Advances in Catalysis for Sustainable Energy and Environmental Remediation)

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14 pages, 4623 KiB

Open AccessArticle

Synergic Effects of Ordered Mesoporous Bifunctional Ionic Liquid: A Recyclable Catalyst to Access Chemoselective N-Protected Indoline-2,3-dione Analogous

by Gouthaman Siddan and Viswas Raja Solomon

Catalysts 2024, 14(9), 629; https://doi.org/10.3390/catal14090629 - 17 Sep 2024

Abstract

SBA-15 and organic ionic liquid were incorporated in a post-grafting technique for generating a bifunctional ionic liquid embedded mesoporous SBA-15. The prepared heterogeneous catalyst was employed for the first time to synthesize N-alkylated indoline-2,3-dione at mild conditions to afford excellent yields in [...] Read more.

SBA-15 and organic ionic liquid were incorporated in a post-grafting technique for generating a bifunctional ionic liquid embedded mesoporous SBA-15. The prepared heterogeneous catalyst was employed for the first time to synthesize N-alkylated indoline-2,3-dione at mild conditions to afford excellent yields in a short reaction time. The synthesized DABCOIL@SBA-15 catalyst was meticulously characterized by various techniques, such as FT-IR, solid-state ¹³C NMR, solid-state ²⁹Si NMR, small-angle X-ray diffraction (XRD), and N₂ adsorption–desorption. Further, the morphological behavior of the catalyst was studied by SEM and TEM. The thermal stability and number of active sites were determined by thermogravimetric analysis (TGA). The Hammett equation was used to analyze the synergetic effect of the catalyst and substituent effects on the N-alkylated products of 5-substituted isatin derivatives, which resulted in a negative slope. This negative slope indicates a positive charge in the transition state. Notably, the DABCOIL@SBA-15 catalyst demonstrated its practicality by being reused for seven cycles with consistently high catalytic activity. Full article

(This article belongs to the Special Issue Mesoporous Nanostructured Materials for Heterogeneous Catalysis)

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15 pages, 3666 KiB

Open AccessArticle

Novel Approach to Organization of Structured Cobalt-Based Fischer–Tropsch Catalyst

by Andrei Gorshkov, Lilia Sineva, Kirill Gryaznov and Vladimir Mordkovich

Catalysts 2024, 14(9), 628; https://doi.org/10.3390/catal14090628 - 17 Sep 2024

Abstract

Structured Fischer–Tropsch synthesis catalysts were tested in tubular reactors of industry-standard diameters of 0.5 or 0.75 inches. The structured catalyst bed was manufactured by the obturation of a straight bunch of graphite-based extrudates (D = 1.5 mm, L = 30 mm). A conventional [...] Read more.

Structured Fischer–Tropsch synthesis catalysts were tested in tubular reactors of industry-standard diameters of 0.5 or 0.75 inches. The structured catalyst bed was manufactured by the obturation of a straight bunch of graphite-based extrudates (D = 1.5 mm, L = 30 mm). A conventional loose bed of granulated catalyst (D = 1.5 mm, L = 3 mm) was tested as a reference. In a 1000–3000 h⁻¹ syngas space velocity range, structured and loose catalyst bed testing showed no significant differences in their main catalytic parameters. Nevertheless, their C₅₊ hydrocarbon group composition was quite different, i.e., the alkene fraction rose from 9 to 23%, while n-alkanes dropped from 81 to 64%. This could be a result of secondary reaction intensification in the conventional loose bed due to its zeolite acid site’s higher availability. Further FTS testing of the structured catalysts in 4000–6000 h⁻¹ manifested distinctive limits in C₅₊ productivity for 0.5 and 0.75 inches of 512 kg C₅₊/(m³ reactor·h) and 362 kg C₅₊/(m³ reactor·h), respectively. This may be explained by limitations in structured bed thermal conductivity. It suggests that the arrangement of extrudates in the structured catalyst can significantly affect the reaction heat and mass transfer conditions and affords new opportunities for group composition control by means of catalyst bed organization. Full article

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

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28 pages, 7085 KiB

Open AccessReview

Tuning the Electronic Structures of Mo-Based Sulfides/Selenides with Biomass-Derived Carbon for Hydrogen Evolution Reaction and Sodium-Ion Batteries

by Hongying Pan, Kaiyang Zheng, Zihan Chen, Yuexin Wang, Yajun Tan, Jian Wang, Luye Yao, Lixin Wang, Chencheng Sun and Jun Yang

Catalysts 2024, 14(9), 627; https://doi.org/10.3390/catal14090627 - 17 Sep 2024

Abstract

A key research focus at present is the exploration and innovation of electrode materials suitable for energy storage and conversion. Molybdenum-based sulfides/selenides (primarily MoS₂ and MoSe₂) have garnered attention in recent years due to their intrinsic two-dimensional structures, which are [...] Read more.

A key research focus at present is the exploration and innovation of electrode materials suitable for energy storage and conversion. Molybdenum-based sulfides/selenides (primarily MoS₂ and MoSe₂) have garnered attention in recent years due to their intrinsic two-dimensional structures, which are conducive to ion/electron transfer or insertion/extraction, making them promising candidates in electrocatalytic hydrogen production and sodium-ion battery applications. However, their inherently poor electronic structures have led most research efforts to concentrate on modifications aimed at enhancing their performance in hydrogen evolution reactions (HERs) and sodium-ion batteries (SIBs). Owing to their remarkable chemical inertness, expansive specific surface areas, and tunable pore architectures, carbon-based materials have garnered significant attention in research. The utilization of biomass as a renewable and environmentally sustainable precursor offers considerable benefits, including abundant availability, ecological compatibility, and cost-effectiveness. Consequently, recent scholarly endeavors have concentrated intensively on the synthesis of valuable carbon materials derived from renewable biomass sources. This review addresses the scientific challenges related to the development of electrode materials for HERs and SIBs in electrochemical energy storage and conversion. It delves into the recent focus on the two-dimensional transition-metal chalcogenides, particularly MoS₂ and MoSe₂, and the difficulties encountered in modulating their electronic structures when applied to HERs and SIBs. The review proposes the use of eco-friendly and widely sourced biomass-derived carbon (BMC) as a supporting matrix combined with MoS₂ and MoSe₂ to regulate their structures and enhance their electrocatalytic activity and sodium storage performance. Additionally, it highlights the existing challenges faced by these BMC/MoS₂ and BMC/MoSe₂ composites and offers insights into future developments. Full article

(This article belongs to the Special Issue Electronic Structures Modulation of Transition Metal Chalcogenides for Energy Storage and Catalysis Applications)

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10 pages, 2750 KiB

Open AccessFeature PaperArticle

Carbon Nanofiber-Encapsulated FeCoNiCuMn Sulfides with Tunable S Doping for Enhanced Oxygen Evolution Reaction

by Yuhan Sun, Chen Shen, Mingran Wang, Yang Cao, Qianwei Wang, Jiayi Rong, Tong He, Duanyang Li and Feng Cao

Catalysts 2024, 14(9), 626; https://doi.org/10.3390/catal14090626 - 17 Sep 2024

Abstract

The oxygen evolution reaction (OER) stands out as a key electrochemical process for the conversion of clean energy. However, the practical implementation of OER is frequently impeded by its slow kinetics and the necessity for scarce and expensive noble metal catalysts. High-entropy transition [...] Read more.

The oxygen evolution reaction (OER) stands out as a key electrochemical process for the conversion of clean energy. However, the practical implementation of OER is frequently impeded by its slow kinetics and the necessity for scarce and expensive noble metal catalysts. High-entropy transition metal sulfides (HETMS) stand at the forefront of OER catalysts, renowned for their exceptional catalytic performance and diversity. Herein, we have synthesized a HETMS catalyst, (FeCoNiCuMn₅₀)S₂, encapsulated within carbon nanofibers through a one-step process involving the synergistic application of electrospinning and chemical vapor deposition. By precisely controlling the doping levels of sulfur, we have demonstrated that sulfur incorporation significantly increases the exposed surface area of alloy particles on carbon nanofibers and optimizes the electronic configuration of the alloy elements. These findings reveal that sulfur doping is instrumental in the substantial improvement of the catalyst’s OER performance. Notably, the catalyst showed optimal activity at a sulfur-to-metal atom ratio of 2:1, delivering an overpotential of 254 mV at a current density of 10 mA cm⁻² in 1.0 M KOH solution. Furthermore, the (FeCoNiCuMn₅₀)S₂ catalyst exhibited remarkable electrochemical stability, underscoring its potential as an efficient and robust OER electrocatalyst for sustainable energy applications. Full article

(This article belongs to the Section Catalytic Materials)

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31 pages, 3833 KiB

Open AccessArticle

Transition Metal-Promoted LDH-Derived CoCeMgAlO Mixed Oxides as Active Catalysts for Methane Total Oxidation

by Marius C. Stoian, Cosmin Romanitan, Katja Neubauer, Hanan Atia, Constantin Cătălin Negrilă, Ionel Popescu and Ioan-Cezar Marcu

Catalysts 2024, 14(9), 625; https://doi.org/10.3390/catal14090625 - 17 Sep 2024

Abstract

A series of M(x)CoCeMgAlO mixed oxides with different transition metals (M = Cu, Fe, Mn, and Ni) with an M content x = 3 at. %, and another series of Fe(x)CoCeMgAlO mixed oxides with Fe contents x ranging from 1 to 9 at. [...] Read more.

A series of M(x)CoCeMgAlO mixed oxides with different transition metals (M = Cu, Fe, Mn, and Ni) with an M content x = 3 at. %, and another series of Fe(x)CoCeMgAlO mixed oxides with Fe contents x ranging from 1 to 9 at. % with respect to cations, while keeping constant in both cases 40 at. % Co, 10 at. % Ce and Mg/Al atomic ratio of 3 were prepared via thermal decomposition at 750 °C in air of their corresponding layered double hydroxide (LDH) precursors obtained by coprecipitation. They were tested in a fixed bed reactor for complete methane oxidation with a gas feed of 1 vol.% methane in air to evaluate their catalytic performance. The physico-structural properties of the mixed oxide samples were investigated with several techniques, such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), elemental mappings, inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction under hydrogen (H₂-TPR) and nitrogen adsorption–desorption at −196 °C. XRD analysis revealed in all the samples the presence of Co₃O₄ crystallites together with periclase-like and CeO₂ phases, with no separate M-based oxide phase. All the cations were distributed homogeneously, as suggested by EDX measurements and elemental mappings of the samples. The metal contents, determined by EDX and ICP-OES, were in accordance with the theoretical values set for the catalysts’ preparation. The redox properties studied by H₂-TPR, along with the surface composition determined by XPS, provided information to elucidate the catalytic combustion properties of the studied mixed oxide materials. The methane combustion tests showed that all the M-promoted CoCeMgAlO mixed oxides were more active than the M-free counterpart, the highest promoting effect being observed for Fe as the doping transition metal. The Fe(x)CoCeMgAlO mixed oxide sample, with x = 3 at. % Fe displayed the highest catalytic activity for methane combustion with a temperature corresponding to 50% methane conversion, T₅₀, of 489 °C, which is ca. 40 °C lower than that of the unpromoted catalyst. This was attributed to its superior redox properties and lowest activation energy among the studied catalysts, likely due to a Fe–Co–Ce synergistic interaction. In addition, long-term tests of Fe(3)CoCeMgAlO mixed oxide were performed, showing good stability over 60 h on-stream. On the other hand, the addition of water vapors in the feed led to textural and structural changes in the Fe(3)CoCeMgAlO system, affecting its catalytic performance in methane complete oxidation. At the same time, the catalyst showed relatively good recovery of its catalytic activity as soon as the water vapors were removed from the feed. Full article

(This article belongs to the Collection Nanocatalysis Towards Energy Transition and Environmental Sustainability)

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12 pages, 5519 KiB

Open AccessFeature PaperArticle

Biomass-Derived Co/MPC Nanocomposites for Effective Sensing of Hydrogen Peroxide via Electrocatalysis Reduction

by Mei Wang, Jin Cai, Lihua Jiao and Quan Bu

Catalysts 2024, 14(9), 624; https://doi.org/10.3390/catal14090624 - 16 Sep 2024

Abstract

Utilizing the full potential of reproducible biomass resources is crucial for the sustainable development of humanity. In this study, biochar (MPC) was prepared through the microwave-assisted pyrolysis of sugarcane bagasse. Subsequently, Co nanoparticles were introduced by microwave-assisted hydrothermal treatment to form a highly [...] Read more.

Utilizing the full potential of reproducible biomass resources is crucial for the sustainable development of humanity. In this study, biochar (MPC) was prepared through the microwave-assisted pyrolysis of sugarcane bagasse. Subsequently, Co nanoparticles were introduced by microwave-assisted hydrothermal treatment to form a highly dispersive Co/MPC material. Characterization results indicated that Co nanoparticles were wrapped by thin carbon layers and uniformly dispersed on a carbon-based skeleton via a microwave-assisted hydrothermal synthesis approach, providing high-activity space. Thus, the prepared material was limited to glassy carbon; on the electrode surface, a cobalt-based sensing platform (Co/MPC/GCE) was built. On the basis of this constructed sensing platform, a linear equation was fitted by the concentration change of current signal I and H₂O₂. The linear range was 0.55–100.05 mM; the detection limit was 1.38 μM (S/N = 3); and the sensitivity was 103.45 μA cm⁻² mM⁻¹. In addition, the effect this sensor had on H₂O₂ detection of actual water samples was conducted by using a standard addition recovery method; results disclosed that the recovery rate and RSD of H₂O₂ in tap water samples were 94.0–97.6% and 4.1–6.5%, respectively. Full article

(This article belongs to the Special Issue Topical Advisory Panel Members' Collection Series: Biomass Catalytic Conversion)

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16 pages, 2560 KiB

Open AccessArticle

Investigation into the Fuel Characteristics of Biodiesel Synthesized through the Transesterification of Palm Oil Using a TiO₂/CH₃ONa Nanocatalyst

by Cherng-Yuan Lin and Shun-Lien Tseng

Catalysts 2024, 14(9), 623; https://doi.org/10.3390/catal14090623 - 16 Sep 2024

Abstract

Biodiesel is a renewable and sustainable alternative fuel to petrol-derived diesel. Decreasing the operating costs by improving the catalyst’s characteristics is an effective way to increase the competitiveness of biodiesel in the fuel market. An aqueous solution of sodium methoxide (CH₃ONa), [...] Read more.

Biodiesel is a renewable and sustainable alternative fuel to petrol-derived diesel. Decreasing the operating costs by improving the catalyst’s characteristics is an effective way to increase the competitiveness of biodiesel in the fuel market. An aqueous solution of sodium methoxide (CH₃ONa), which is a traditional alkaline catalyst, was immersed in nanometer-sized particles of titanium dioxide (TiO₂) powder to prepare the strong alkaline catalyst TiO₂/CH₃ONa. The immersion method was used to enhance the transesterification reaction. The mixture of TiO₂ and CH₃ONa was calcined in a high-temperature furnace in a range between 150 and 450 °C continuously for 4 h. The heterogeneous alkaline catalyst TiO₂/CH₃ONa was then used to catalyze the strong alkaline transesterification reaction of palm oil with methanol. The highest content of fatty acid methyl esters (FAMEs), which amounted to 95.9%, was produced when the molar ratio of methanol to palm oil was equal to 6, and 3 wt.% TiO₂/CH₃ONa was used, based on the weight of the palm oil. The FAMEs produced from the above conditions were also found to have the lowest kinematic viscosity of 4.17 mm²/s, an acid value of 0.32 mg KOH/g oil, and a water content of 0.031 wt.%, as well as the highest heating value of 40.02 MJ/kg and cetane index of 50.05. The lower catalyst amount of 1 wt.%, in contrast, resulted in the lowest cetane index of 49.31. The highest distillation temperature of 355 °C was found when 3 wt.% of the catalyst was added to the reactant mixture with a methanol/palm oil molar ratio of 6. The prepared catalyst is considered effective for improving the fuel characteristics of biodiesel. Full article

(This article belongs to the Special Issue Topical Advisory Panel Members' Collection Series: Biomass Catalytic Conversion)

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11 pages, 2390 KiB

Open AccessFeature PaperArticle

Catalytic Decontamination of Carbon Monoxide Using Strong Metal–Support Interactions on TiO₂ Microparticles

by Avraham Dayan, Jacob Alter and Gideon Fleminger

Catalysts 2024, 14(9), 622; https://doi.org/10.3390/catal14090622 - 15 Sep 2024

Abstract

The traditional catalytic oxidation of carbon monoxide (CO) using metal oxide catalysts often requires either high temperatures (thermocatalysis) or ultraviolet light (UV) excitation (photocatalysis), limiting practical applications under ambient conditions. Our research aimed to develop a catalytic system capable of oxidizing CO to [...] Read more.

The traditional catalytic oxidation of carbon monoxide (CO) using metal oxide catalysts often requires either high temperatures (thermocatalysis) or ultraviolet light (UV) excitation (photocatalysis), limiting practical applications under ambient conditions. Our research aimed to develop a catalytic system capable of oxidizing CO to CO₂ at room temperature and in the dark. Using the Strong Metal–Support Interaction (SMSI) methodology, several titanium oxide (TiO₂)-complexed metals were prepared (Ag, Au, Pd, and Pt). The highest catalytic efficiency of CO oxidation at room temperature was demonstrated for the TiO₂-Pt complex. Therefore, this complex was further examined structurally and functionally. Two modes of operation were addressed. The first involved applying the catalytic system to remove CO from an individual’s environment (environmental system), while the second involved the installation of the catalysis chamber as a part of a personal protection unit (e.g., a mask). The catalytic activity exhibited a significant reduction in CO levels in both the environmental and personal protection scenarios. The practical application of the system was demonstrated through efficient CO oxidation in air emitted from a controlled fire experiment conducted in collaboration with the Israel Fire and Rescue Authority. Full article

(This article belongs to the Special Issue Catalytic CO Oxidation and Preferential CO Oxidation (PROX) II)

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16 pages, 12097 KiB

Open AccessArticle

Insight into the Structural and Performance Correlation of Photocatalytic TiO₂/Cu Composite Films Prepared by Magnetron Sputtering Method

by Kun Lu, Miao Sun, Yaohong Jiang, Xinmeng Wu, Lijun Zhao and Junhua Xu

Catalysts 2024, 14(9), 621; https://doi.org/10.3390/catal14090621 - 14 Sep 2024

Abstract

Photocatalysis technology, as an efficient and safe environmentally friendly purification technique, has garnered significant attention and interest. Traditional TiO₂ photocatalytic materials still face limitations in practical applications, hindering their widespread adoption. The research prepared TiO₂/Cu films with different Cu contents [...] Read more.

Photocatalysis technology, as an efficient and safe environmentally friendly purification technique, has garnered significant attention and interest. Traditional TiO₂ photocatalytic materials still face limitations in practical applications, hindering their widespread adoption. The research prepared TiO₂/Cu films with different Cu contents using a magnetron sputtering multi-target co-deposition technique. The incorporation of Cu significantly enhances the antibacterial properties and visible light response of the films. The effects of different Cu contents on the microstructure, surface morphology, wettability, antibacterial properties, and visible light response of the films were investigated using an X-ray diffractometer, X-ray photoelectron spectrometer, field emission scanning electron microscope, confocal laser scanning microscope, Ultraviolet–visible spectrophotometer, and contact angle goniometer. The results showed that the prepared TiO₂/Cu films were mainly composed of the rutile TiO₂ phase and face-center cubic Cu phase. The introduction of Cu affected the crystal orientation of TiO₂ and refined the grain size of the films. With the increase in Cu content, the surface roughness of the films first decreased and then increased. The water contact angle of the films first increased and then decreased, and the film exhibited optimal hydrophobicity when the Cu target power was 10 W. The TiO₂/Cu films showed good antibacterial properties against Escherichia coli and Staphylococcus aureus. The introduction of Cu shifted the absorption edge of the films to the red region, significantly narrowed the band gap width to 2.5 eV, and broadened the light response range of the films to the visible light region. Full article

(This article belongs to the Special Issue Tailored Nanosystems and Nanocatalysts for Photo-/Electrocatalytic Applications, 2nd Edition)

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20 pages, 1236 KiB

Open AccessArticle

Photo-Fenton Treatment under UV and Vis Light Reduces Pollution and Toxicity in Water from Madín Dam, Mexico

by Deysi Amado-Piña, Rubi Romero, Emmanuel Salazar Carmona, Armando Ramírez-Serrano, Leobardo Manuel Gómez-Oliván, Gustavo Elizalde-Velázquez and Reyna Natividad

Catalysts 2024, 14(9), 620; https://doi.org/10.3390/catal14090620 - 14 Sep 2024

Abstract

Water from Madín Dam in Mexico has been shown to contain a wide variety of pollutants such as drugs, pesticides, personal care products and compounds that are released into the environment as waste from production processes. In this work, the effect of the [...] Read more.

Water from Madín Dam in Mexico has been shown to contain a wide variety of pollutants such as drugs, pesticides, personal care products and compounds that are released into the environment as waste from production processes. In this work, the effect of the main process variables on the percentage of total organic carbon (TOC) removal in water samples from the Madín reservoir was studied by applying a photo-Fenton treatment catalyzed with iron-pillared clays. The catalyst was characterized by XRD, N₂ physisorption, DRS and XPS. The sampling and characterization of the water from the Madín reservoir was carried out according to Mexican standards. The system for treatment tests was 0.1 L of reaction volume and a controlled temperature of 23–25 °C, and the reaction system was kept under constant stirring. After 4 h of treatment time under UV light, the TOC removal was 90%, and it was 60% under Vis light. The main ROS involved in the photo-Fenton process driven by UVC light were hydroxyl radicals, while hydroperoxyl radicals predominate in the Vis-light-driven process. Evidence of superoxide anion participation was not found. The toxicity of untreated and treated water was assessed on Danio rerio specimens, and it was observed to be reduced after the photo-Fenton treatment. Full article

(This article belongs to the Section Photocatalysis)

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18 pages, 4620 KiB

Open AccessFeature PaperArticle

Fractal Behavior of Nanostructured Pt/TiO₂ Catalysts: Synthesis, Characterization and Evaluation of Photocatalytic Hydrogen Generation

by Anca Vasile, Gianina Dobrescu, Veronica Bratan, Mircea Teodorescu, Cornel Munteanu, Irina Atkinson, Catalin Negrila, Florica Papa and Ioan Balint

Catalysts 2024, 14(9), 619; https://doi.org/10.3390/catal14090619 - 13 Sep 2024

Abstract

The fractal characterization of supported nanoparticles is a useful tool for obtaining structural and morphological information that strongly impacts catalytic properties. We have synthesized and characterized Pt supported on TiO₂ nanostructures. Triblock copolymers with thermosensitive properties were used as templating agents during [...] Read more.

The fractal characterization of supported nanoparticles is a useful tool for obtaining structural and morphological information that strongly impacts catalytic properties. We have synthesized and characterized Pt supported on TiO₂ nanostructures. Triblock copolymers with thermosensitive properties were used as templating agents during the synthesis process. In addition to the several techniques used for the characterization of the materials, we carried out fractal analysis. The prepared materials showed a reduction in the band gap of TiO₂ from 3.44 to 3.01 eV. The extended absorption in the 500–700 nm regions is mostly attributed to the presence of supported Pt nanoparticles. The ability of the nanostructured Pt/TiO₂ catalysts to generate H₂ in an aqueous solution was evaluated. The test reaction was carried out in the presence of methanol, as a hole scavenger, under simulated solar light. Pt/TiO₂-3TB shows the highest rate of H₂ (4.17 mmol h⁻¹ g_cat⁻¹) when compared to Pt/TiO₂-0TB (3.65 mmol h⁻¹ g_cat⁻¹) and Pt/TiO₂-6TB (2.29 mmol h⁻¹ g_cat⁻¹) during simulated solar light irradiation. Pt/TiO₂-3TB exhibits a more structured organization (fractal dimensions of 1.65–1.74 nm at short scales, 1.27–1.30 nm at long scales) and a distinct fractal behavior. The generation of hydrogen via photocatalysis can be linked to the fractal characteristics. Full article

(This article belongs to the Special Issue Effect of the Modification of Catalysts on the Catalytic Performance, 2nd Edition)

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47 pages, 6874 KiB

Open AccessReview

Nanoalchemy: Unveiling the Power of Carbon Nanostructures and Carbon–Metal Nanocomposites in Synthesis and Photocatalytic Activity

by Yalini Devi Neelan, Senthil Bakthavatchalam, Shanmugam Mahalingam, Krishnasamy Sreenivason Yoganand, Shunmuga Vadivu Ramalingam, Umamaheswari Rajendran, Rajasekaran Ramu, Tae-Youl Yang, Junghwan Kim and Raji Atchudan

Catalysts 2024, 14(9), 618; https://doi.org/10.3390/catal14090618 - 13 Sep 2024

Abstract

Due to a rise in industrial pollutants in modern life, the climate and energy crisis have grown more widespread. One of the best ways to deal with dye degradation, hydrogen production, and carbon dioxide reduction issues is the photocatalytic technique. Among various methods, [...] Read more.

Due to a rise in industrial pollutants in modern life, the climate and energy crisis have grown more widespread. One of the best ways to deal with dye degradation, hydrogen production, and carbon dioxide reduction issues is the photocatalytic technique. Among various methods, catalytic technology has demonstrated tremendous promise in recent years as a cheap, sustainable, and environmentally benign technology. The expeditious establishment of carbon-based metal nanoparticles as catalysts in the disciplines of materials and chemical engineering for catalytic applications triggered by visible light is largely attributed to their advancement. There have been many wonderful catalysts created, but there are still many obstacles to overcome, which include the cost of catalysts being reduced and their effectiveness being increased. Carbon-based materials exhibit a unique combination of characteristics that make them ideal catalysts for various reaction types. These characteristics include an exceptional electrical conductivity, well-defined structures at the nanoscale, inherent water repellency, and the ability to tailor surface properties for specific applications. This versatility allows them to be effective in diverse catalytic processes, encompassing organic transformations and photocatalysis. The emergence of carbon-based nanostructured materials, including fullerenes, carbon dots, carbon nanotubes, graphitic carbon nitride, and graphene, presents a promising alternative to conventional catalysts. This review focuses on the diverse functionalities of these materials within the realm of catalysis materials for degradation, hydrogen production, and carbon dioxide reduction. Additionally, it explores the potential for their commercialization, delving into the underlying mechanisms and key factors that influence their performance. It is anticipated that this review will spur more research to develop high-performance carbon-based materials for environmental applications. Full article

(This article belongs to the Special Issue Nanostructures for Catalysis: From Synthesis and Characterization to Applications)

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11 pages, 1981 KiB

Open AccessFeature PaperArticle

Continuous Flow Synthesis of Furfuryl Ethers over Pd/C Catalysts via Reductive Etherification of Furfural in Ethanol

by Ayoub Hassine, Anas Iben Ayad, Aïssa Ould Dris, Denis Luart and Erwann Guénin

Catalysts 2024, 14(9), 617; https://doi.org/10.3390/catal14090617 - 13 Sep 2024

Abstract

Furfural has become one of the most promising building blocks directly derived from biomass. It can be transformed into numerous important biobased chemicals. Among them, furfuryl ethers such as furfuryl ethyl ether (FEE) and tetrahydrofurfuryl ethyl ether (THFEE) are considered to be attractive [...] Read more.

Furfural has become one of the most promising building blocks directly derived from biomass. It can be transformed into numerous important biobased chemicals. Among them, furfuryl ethers such as furfuryl ethyl ether (FEE) and tetrahydrofurfuryl ethyl ether (THFEE) are considered to be attractive derivatives, notably as fuel components, due to their high stability and high octane numbers. Therefore, the production of furfuryl ethers from furfural via a hydrogenation route is an important academic and industrial challenge and requires the deployment of new catalytic processes under green and competitive reaction conditions. The existing processes are based on a two-step process combining hydrogenation and reaction with a strong Bronsted acid catalyst in batch conditions. For the first time, a continuous flow one-step process has been elaborated for the conversion of furfural directly into furfuryl ethers based on reductive etherification. The present work explores the catalytic performance in a continuous flow of commercial palladium catalysts supported on activated carbon for the catalytic reductive etherification of furfural with ethanol in the presence of trifluoroacetic acid. The chemical and engineering aspects, such as the mechanisms and reaction conditions, will be discussed. Full article

(This article belongs to the Special Issue Industrial Applications of High-Value Added Biomass Conversion)

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30 pages, 6114 KiB

Open AccessArticle

Roles of Catalysts and Feedstock in Optimizing the Performance of Heavy Fraction Conversion Processes: Fluid Catalytic Cracking and Ebullated Bed Vacuum Residue Hydrocracking

by Dicho Stratiev, Ivelina Shishkova, Georgi Argirov, Rosen Dinkov, Mihail Ivanov, Sotir Sotirov, Evdokia Sotirova, Veselina Bureva, Svetoslav Nenov, Krassimir Atanassov, Denis Stratiev and Svetlin Vasilev

Catalysts 2024, 14(9), 616; https://doi.org/10.3390/catal14090616 - 12 Sep 2024

Abstract

Petroleum refining has been, is still, and is expected to remain in the next decades the main source of energy required to drive transport for mankind. The demand for automotive and aviation fuels has urged refiners to search for ways to extract more [...] Read more.

Petroleum refining has been, is still, and is expected to remain in the next decades the main source of energy required to drive transport for mankind. The demand for automotive and aviation fuels has urged refiners to search for ways to extract more light oil products per barrel of crude oil. The heavy oil conversion processes of ebullated bed vacuum residue hydrocracking (EBVRHC) and fluid catalytic cracking (FCC) can assist refiners in their aim to produce more transportation fuels and feeds for petrochemistry from a ton of petroleum. However, a good understanding of the roles of feed quality and catalyst characteristics is needed to optimize the performance of both heavy oil conversion processes. Three knowledge discovery database techniques—intercriteria and regression analyses, and artificial neural networks—were used to evaluate the performance of commercial FCC and EBVRHC in processing 19 different heavy oils. Seven diverse FCC catalysts were assessed using a cascade and parallel fresh catalyst addition system in an EBVRHC unit. It was found that the vacuum residue conversion in the EBVRHC depended on feed reactivity, which, calculated on the basis of pilot plant tests, varied by 16.4%; the content of vacuum residue (VR) in the mixed EBVRHC unit feed (each 10% fluctuation in VR content leads to an alteration in VR conversion of 1.6%); the reaction temperature (a 1 °C deviation in reaction temperature is associated with a 0.8% shift in VR conversion); and the liquid hourly space velocity (0.01 h-1 change of LHSV leads to 0.85% conversion alteration). The vacuum gas oil conversion in the FCC unit was determined to correlate with feed crackability, which, calculated on the basis of pilot plant tests, varied by 8.2%, and the catalyst ΔCoke (each 0.03% ΔCoke increase reduces FCC conversion by 1%), which was unveiled to depend on FCC feed density and equilibrium FCC micro-activity. The developed correlations can be used to optimize the performance of FCC and EBVRHC units by selecting the appropriate feed slate and catalyst. Full article

(This article belongs to the Section Catalytic Reaction Engineering)

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20 pages, 6133 KiB

Open AccessArticle

Synthesis of In-Modified TiO₂ Composite Materials from Waste Tobacco Stem Silk and Study of Their Catalytic Performance under Visible Light

by Junyang Leng, Yi Zhao, Jindi Zhang, Xiaoli Bai, Anlong Zhang, Quanhui Li, Mengyang Huang and Jiaqiang Wang

Catalysts 2024, 14(9), 615; https://doi.org/10.3390/catal14090615 - 12 Sep 2024

Abstract

Titanium dioxide (TiO₂) catalysts are primarily utilized under ultraviolet light, and their potential in industrial applications remains largely untapped. To address this issue, our study uses a one-pot impregnation method to prepare a series of In-TiO₂/TSS(X) (TSS, Tobacco stem [...] Read more.

Titanium dioxide (TiO₂) catalysts are primarily utilized under ultraviolet light, and their potential in industrial applications remains largely untapped. To address this issue, our study uses a one-pot impregnation method to prepare a series of In-TiO₂/TSS(X) (TSS, Tobacco stem silk. X, the molar ratio of In/Ti) catalysts. Among them, the degradation performance of the In-TiO₂/TSS(2.0) material increased from 13.8% for TiO₂ to an impressive 92.9%. By establishing a first-order kinetic model, it was determined that the degradation performance of the In-TiO₂/TSS(2.0) material surpassed that of TiO₂ by a factor of 24. Structural characterization revealed that the introduction of tobacco stem silk templates did not alter the crystal phase of TiO₂ and that the main component of the catalyst remained TiO₂. Not only that, an O–In structure formed on the surface of the TiO₂, leading to a significant increase in the material’s specific surface area. Furthermore, principle tests were conducted, revealing significant enhancements in its light absorption capacity, intensity, and photocurrent density. Through active species trapping experiments, it was observed that, in the photocatalytic degradation process of this catalyst series, holes (h⁺) played the primary role, while the hydroxyl ion (·OH) and superoxide ion (·O²⁻) acted as auxiliary species. Full article

(This article belongs to the Special Issue Cutting-Edge Photocatalysis)

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