Catalysts

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12 pages, 2979 KiB

Open AccessArticle

Efficient Synthesis of Nickel-Molybdenum/USY-Zeolite Catalyst for Eliminating Impurities (N, S, and Cl) in the Waste Plastic Pyrolysis Oil: Dispersion Effect of Active Sites by Surfactant-Assisted Melt-Infiltration

by Eui Hyun Cho, Ki-Duk Kim, Byung Sun Yoon, Eunkyung Cho, Yeon Jeong Yu, Tuan Ngoc Phan, Sang-Goo Jeon and Chang Hyun Ko

Catalysts 2023, 13(12), 1476; https://doi.org/10.3390/catal13121476 - 28 Nov 2023

Cited by 1 | Viewed by 1034

Abstract

The upgrading of waste plastic pyrolysis oil (WPPO) through hydrotreating (HDT) is crucial for transforming plastic waste into chemical feedstock. The catalytic role of HDT is of paramount importance for this conversion procedure. In this study, bimetallic catalysts based on Ni and Mo [...] Read more.

The upgrading of waste plastic pyrolysis oil (WPPO) through hydrotreating (HDT) is crucial for transforming plastic waste into chemical feedstock. The catalytic role of HDT is of paramount importance for this conversion procedure. In this study, bimetallic catalysts based on Ni and Mo were prepared using the surfactant-assisted melt-infiltration (SAMI) method, completely omitting the use of liquid solutions. Thorough analysis via X-ray diffraction, transmission electron microscopy, and hydrogen temperature-programmed reduction confirmed that the addition of Span60 surfactant effectively prevented the aggregation of Ni and Mo components, reduced the size of metal particles, and improved the dispersion of active sites on the zeolite supports. Consequently, NiMo-based catalysts incorporating Span60, synthesized using the SAMI method, exhibited a superior catalytic performance in the removal of nitrogen, sulfur, and chloride impurities from WPPO during HDT compared to those without surfactant. Specifically, the catalyst prepared with Span60 exhibited 15% higher nitrogen conversion compared to the catalyst prepared without Span60. Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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13 pages, 4439 KiB

Open AccessFeature PaperArticle

Effect of Hydrogen Adsorption on Pt Nanoparticle Encapsulated in NaY Zeolite: Combined Study of WT XAFS and DFT Calculation

by Sung June Cho, Chang Hyun Ko and Chanho Pak

Catalysts 2023, 13(8), 1191; https://doi.org/10.3390/catal13081191 - 8 Aug 2023

Viewed by 959

Abstract

Extensive research has been conducted on platinum nanoparticles or clusters supported on zeolite for various catalytic applications, primarily due to the well-defined structure contained within the pore. The preparation and characterization of these particles have been thoroughly examined using advanced techniques such as [...] Read more.

Extensive research has been conducted on platinum nanoparticles or clusters supported on zeolite for various catalytic applications, primarily due to the well-defined structure contained within the pore. The preparation and characterization of these particles have been thoroughly examined using advanced techniques such as X-ray absorption fine structures (XAFSs), both in situ and ex situ. In this study, we employed the Wavelet method to analyze the structure of platinum nanoparticles encapsulated within the supercage of a Y zeolite, where XAFS data were collected over a temperature range of 100 K to 423 K, both with and without hydrogen. The adsorption of hydrogen caused a relaxation in the structure of the platinum nanoparticles, thus leading to a decrease in the Pt–Pt distance and resulting in a lower Debye–Waller factor compared to bare nanoparticles. This structural change induced by hydrogen chemisorption aligns with the findings of the density functional theory (DFT) calculations for Pt₁₃ nanoparticles located in the supercage. The relaxation of the structure results in charge redistribution, thereby ultimately generating atomic hydrogen with a partial negative charge, which is crucial for catalytic processes. Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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14 pages, 4548 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Efficient and Stable Ni/SBA-15 Catalyst for Dry Reforming of Methane: Effect of Citric Acid Concentration

by Mamoona Waris, Howon Ra, Sungmin Yoon, Min-Jae Kim and Kyubock Lee

Catalysts 2023, 13(6), 916; https://doi.org/10.3390/catal13060916 - 23 May 2023

Cited by 4 | Viewed by 1621

Abstract

Citric acid, one of the representative chelate compounds, has been widely used as an additive to achieve the highly dispersed metal-supported catalysts. This study aimed to investigate the effect of citric acid concentration on the preparation of the highly dispersed Ni catalysts on [...] Read more.

Citric acid, one of the representative chelate compounds, has been widely used as an additive to achieve the highly dispersed metal-supported catalysts. This study aimed to investigate the effect of citric acid concentration on the preparation of the highly dispersed Ni catalysts on mesoporous silica (SBA-15) for the dry reforming of methane. A series of Ni/SBA-15 catalysts with citric acid were prepared using the acid-assisted incipient wetness impregnation method, and the Ni/SBA-15 catalyst as a reference was synthesized via the impregnation method. First of all, the citric acid addition during the catalyst synthesis step regardless of its concentration resulted in highly dispersed Ni particles of ~4–7 nm in size in Ni/SBA-15 catalysts, which had a superior and stable catalytic performance in the dry reforming of methane (93% of CO₂ conversion and 86% of CH₄ conversion). In addition, the amount of coke formation was much lower in a series of Ni/SBA-15 catalysts with citric acid (~2–5 mg_coke g_cat⁻¹ h⁻¹) compared to pristine Ni/SBA-15 catalysts (~22 mg_coke g_cat⁻¹ h⁻¹). However, when the concentration of citric acid became higher, the more free NiO species that formed on the SBA-15 support, leading to large Ni particles after the stability test. The addition of citric acid is a very clear strategy for making highly dispersed catalysts, but its concentration needs to be carefully controlled. Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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11 pages, 8087 KiB

Open AccessFeature PaperArticle

Synthesis of Cobalt Complex Containing Trans-Cinnamate and Its Electrocatalytic Activity for Oxygen Evolution Reaction

by Jimin Lee, Hyewon Shin, Sunwoo Geum, Sowon Lee, Kang Min Ok, Junghwan Do and Seong Jung Kwon

Catalysts 2023, 13(3), 507; https://doi.org/10.3390/catal13030507 - 1 Mar 2023

Cited by 2 | Viewed by 1482

Abstract

There are many efforts reported on finding effective catalysts for oxygen evolution reactions (OERs), which are important reactions in the energy field. Coordination polymers, including metal–organic frameworks (MOFs), are attracting attention as electrocatalysts for OERs due to their versatility and modulating properties. A [...] Read more.

There are many efforts reported on finding effective catalysts for oxygen evolution reactions (OERs), which are important reactions in the energy field. Coordination polymers, including metal–organic frameworks (MOFs), are attracting attention as electrocatalysts for OERs due to their versatility and modulating properties. A new cobalt complex containing trans-cinnamate and 2-aminopyridmidine ligands was synthesized using a hydrothermal method. The cobalt complex showed a 1D chain structure. The electrocatalytic activity and stability of the cobalt complex with or without an electrochemical supporter, such as reduced graphene oxide (rGO), OERs were investigated and compared with a metal oxide reference material. Due to the π-conjugated trans-cinnamate, which has electron flexibility near the Co centers, the catalyst/rGO composite showed significant catalytic activities, with an overpotential of 386 mV and a Tafel slope of 64 mV/dec. Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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13 pages, 3559 KiB

Open AccessArticle

Synthesis of Hollow Leaf-Shaped Iron-Doped Nickel–Cobalt Layered Double Hydroxides Using Two-Dimensional (2D) Zeolitic Imidazolate Framework Catalyzing Oxygen Evolution Reaction

by Quoc Hao Nguyen, Kyungmin Im and Jinsoo Kim

Catalysts 2023, 13(2), 403; https://doi.org/10.3390/catal13020403 - 14 Feb 2023

Cited by 4 | Viewed by 1668

Abstract

Layered double hydroxides (LDHs) have been reported as one of the most effective materials for oxygen evolution reaction (OER) catalysts, which are prone to hydrolysis and oxidation under OER conditions. Metal–organic frameworks (MOFs) are porous materials with high crystallinity and internal surface area. [...] Read more.

Layered double hydroxides (LDHs) have been reported as one of the most effective materials for oxygen evolution reaction (OER) catalysts, which are prone to hydrolysis and oxidation under OER conditions. Metal–organic frameworks (MOFs) are porous materials with high crystallinity and internal surface area. The design of LDHs based on MOFs has attracted increasing attention owing to their high surface area, exposed catalysis sites, and fast charge/mass transport kinetics. Herein, we report a novel approach to fabricate a leaf-shaped iron-doped nickel–cobalt LDH (L-Fe-NiCoLDH) derived from a two-dimensional (2D) zeolitic imidazolate framework with a leaf-like morphology (ZIFL). Iron doping played a significant role in enhancing the specific surface area, affecting the OER performance. L-Fe-NiCoLDH showed high OER performance with an overpotential of 243 mV at 10 mA cm⁻² and high durability after 20 h. The design of LDHs based on the leaf morphology of MOFs offers tremendous potential for improving OER efficiency. Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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11 pages, 2495 KiB

Open AccessArticle

Reactivity of Sulfur and Nitrogen Compounds of FCC Light Cycle Oil in Hydrotreating over CoMoS and NiMoS Catalysts

by Jihyun Kim and Yong-Kul Lee

Catalysts 2023, 13(2), 277; https://doi.org/10.3390/catal13020277 - 26 Jan 2023

Cited by 2 | Viewed by 1416

Abstract

NiMoS and CoMoS catalysts were synthesized and applied to hydrotreating (HDT) of FCC light cycle oils (FCC-LCO) in an autoclave batch reactor at 613 K and 8.6 MPa H₂. The S and N compounds in LCO were classified into four and [...] Read more.

NiMoS and CoMoS catalysts were synthesized and applied to hydrotreating (HDT) of FCC light cycle oils (FCC-LCO) in an autoclave batch reactor at 613 K and 8.6 MPa H₂. The S and N compounds in LCO were classified into four and three groups, respectively, in terms of the HDT reactivity. The individual and the competitive reactivities of the S and N compounds in the HDS and the HDN were investigated over the conventional CoMoS and NiMoS catalysts using S and N model compounds (dibenzothiophene, DBT, and carbazole, CBZ). In the HDS of DBT, both the direct desulfurization (DDS) and pre-hydrogenation pathway (HYD) were found to proceed, whereas the HYD pathway was favored for the HDN of CBZ. As a result, the NiMoS catalyst that facilitates the HYD pathway showed better activity in the HDN of LCO than the CoMoS (k = 10.20 × 10⁻² vs. 1.80 × 10⁻² h⁻¹). Indeed, the HDS of LCO over the NiMoS was more favorable than that over the CoMoS catalyst (k = 4.3 × 10⁻¹ vs. 3.6 × 10⁻¹ h⁻¹). Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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10 pages, 2123 KiB

Open AccessArticle

Design of Bimetallic PtFe-Based Reduced Graphene Oxide as Efficient Catalyst for Oxidation Reduction Reaction

by Bathinapatla Sravani, Yenugu Veera Manohara Reddy, Jong Pil Park, Manthrapudi Venu and Loka Subramanyam Sarma

Catalysts 2022, 12(12), 1528; https://doi.org/10.3390/catal12121528 - 27 Nov 2022

Cited by 4 | Viewed by 1301

Abstract

Oxygen reduction reaction (ORR) is a very important reaction that occurs at the cathodic side in proton exchange membrane fuel cells (PEMFCs). The high cost associated with frequently used Pt-based electrocatalysts for ORR limits the commercialization of PEMFCs. Through bifunctional and electronic effects, [...] Read more.

Oxygen reduction reaction (ORR) is a very important reaction that occurs at the cathodic side in proton exchange membrane fuel cells (PEMFCs). The high cost associated with frequently used Pt-based electrocatalysts for ORR limits the commercialization of PEMFCs. Through bifunctional and electronic effects, theoretical calculations have proved that alloying Pt with a suitable transition metal is likely to improve ORR mass activity when compared to Pt-alone systems. Herein, we demonstrate the preparation of bimetallic Pt–Fe nanoparticles supported on reduced graphene oxide sheets (RGOs) via a simple surfactant-free chemical reduction method. The present method produces PtFe/RGO catalyst particles with a 3.2 nm diameter without agglomeration. PtFe/RGO showed a noticeable positive half-wave potential (0.503 V vs. Ag/AgCl) compared with a commercial Pt/C catalyst (0.352 V vs. Ag/AgCl) with minimal Pt-loading on a glassy carbon electrode. Further, PtFe/RGO showed a higher ORR mass activity of 4.85 mA/cm²-geo compared to the commercial Pt/C (3.60 mA/cm²-geo). This work paves the way for designing noble−transition metal alloy electrocatalysts on RGO supports as high-performance electrocatalysts for ORR application. Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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17 pages, 6075 KiB

Open AccessArticle

A Remarkable Photocatalyst Filter for Indoor Air Treatment

by Vijayarohini Parasuraman, Parasuraman Perumalswamy Sekar, Hojae Lee, Mahshab Sheraz, Woo Ram Lee, Tae Young Park and Seungdo Kim

Catalysts 2022, 12(11), 1433; https://doi.org/10.3390/catal12111433 - 14 Nov 2022

Cited by 2 | Viewed by 1762

Abstract

A crucial environmental public health risk is air pollution caused by organic contaminants, bio-aerosols, and fine particulate matter (PM_2.5–10). A multi-purpose photocatalyst filter with photocatalytic nitrogen-doped titanium dioxide (PNT) incorporated into non-woven polymer fibers (NWPF) with wide applications is focused on [...] Read more.

A crucial environmental public health risk is air pollution caused by organic contaminants, bio-aerosols, and fine particulate matter (PM_2.5–10). A multi-purpose photocatalyst filter with photocatalytic nitrogen-doped titanium dioxide (PNT) incorporated into non-woven polymer fibers (NWPF) with wide applications is focused on in detail in this work. Loading of PNT on NWPF is carried out by the simple dip coating method. Para-xylene is selected as the target pollutant for the removal of organic contaminants. Higher removal efficiency of p-xylene (94.2%) is achieved under fluorescent daylight. The filtration efficiency of PNT is also evaluated to capture PM_2.5–10, which is increased with higher loading content of PNT. At a high air flow rate, the filtration efficiency of the photocatalyst PNT/NWPF is 97.33%, whereas the efficiency of the pristine NWPF is 91.1%. Moreover, the PNT/NWPF filter exhibits excellent antibacterial activity (99.9%) under visible light irradiation, but the pristine NWPF filter has negligible destruction effects on pathogens. These results clearly indicate that a PNT-coated NWPF filter would be an outstanding multi-purpose material for indoor air purification systems. Full article

(This article belongs to the Special Issue State-of-the-Art of Catalytical Technology in Korea)

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