Research

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12 pages, 7538 KiB

Open AccessEditor’s ChoiceArticle

Semi-Hydrogenation of Acetylene to Ethylene Catalyzed by Bimetallic CuNi/ZSM-12 Catalysts

by Song Hu, Chong Zhang, Mingyu Wu, Runping Ye, Depan Shi, Mujin Li, Peng Zhao, Rongbin Zhang and Gang Feng

Catalysts 2022, 12(9), 1072; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12091072 - 19 Sep 2022

Cited by 4 | Viewed by 2017

Abstract

The purpose of this work is to develop a low-cost and high-performance catalyst for the selective catalytic hydrogenation of acetylene to ethylene. Non-precious metals Cu and Ni were selected as active ingredients for this study. Using ZSM-12 as a carrier, Cu-Ni bimetallic catalysts [...] Read more.

The purpose of this work is to develop a low-cost and high-performance catalyst for the selective catalytic hydrogenation of acetylene to ethylene. Non-precious metals Cu and Ni were selected as active ingredients for this study. Using ZSM-12 as a carrier, Cu-Ni bimetallic catalysts of CuNi_x/ZSM-12 (x = 5, 7, 9, 11) with different Ni/Cu ratios were prepared by incipient wetness impregnation method. The total Cu and Ni loading were 2 wt%. Under the optimal reaction conditions, the acetylene conversion was 100%, and the ethylene selectivity was 82.48%. The CuNi₇/ZSM-12 prepared in this work exhibits good performance in the semi-hydrogenation of acetylene to ethylene with low cost and has potential for industrial application. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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32 pages, 7077 KiB

Open AccessArticle

Biochemical and Physical Characterization of Immobilized Candida rugosa Lipase on Metal Oxide Hybrid Support

by Nurfadhila Nasya Ramlee, Rosli Md Illias, Roshanida A. Rahman, Susilawati Toemen, Rangabhashiyam Selvasembian, Rabi’atul Adawiyah Ahmad, Nor Hasmaliana Abdul Manas and Nur Izyan Wan Azelee

Catalysts 2022, 12(8), 854; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12080854 - 03 Aug 2022

Cited by 6 | Viewed by 2061

Abstract

Enzyme immobilization on inorganic materials is gaining more attention with the potential characteristics of high-surface-area-to-volume ratios, increasing the efficiency of enzyme loading on the support. Metal oxide hybrid support was prepared by a wetness impregnation of five metal precursors, including CaO, CuO, MgO, [...] Read more.

Enzyme immobilization on inorganic materials is gaining more attention with the potential characteristics of high-surface-area-to-volume ratios, increasing the efficiency of enzyme loading on the support. Metal oxide hybrid support was prepared by a wetness impregnation of five metal precursors, including CaO, CuO, MgO, NiO, and ZnO, on Al₂O₃ and used as a support for the immobilization of Candida rugosa lipase (CRL) by adsorption. Maximum activity recovery (70.6%) and immobilization efficiency (63.2%) were obtained after optimization of five parameters using response surface methodology (RSM) by Box–Behnken design (BBD). The biochemical properties of immobilized CRL showed high thermostability up to 70 °C and a wide range in pH stability (pH 4–10). TGA-DTA and FTIR analysis were conducted, verifying thermo-decomposition of lipase and the presence of an amide bond. FESEM-EDX showed the homogeneous distribution and high dispersion of magnesium and CRL on MgO-Al₂O₃, while a nitrogen adsorption–desorption study confirmed MgO-Al₂O₃ as a mesoporous material. CRL/MgO-Al₂O₃ can be reused for up to 12 cycles and it demonstrated high tolerance in solvents (ethanol, isopropanol, methanol, and tert-butanol) compared to free CRL. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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13 pages, 2978 KiB

Open AccessArticle

Effects of Promoter’s Composition on the Physicochemical Properties of Cu/ZnO/Al₂O₃-ZrO₂ Catalyst

by Nur Insyirah Zulkifli, Noor Asmawati Mohd Zabidi, Zulkifli Merican Aljunid Merican and Sara Faiz Hanna Tasfy

Catalysts 2022, 12(6), 636; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12060636 - 10 Jun 2022

Cited by 1 | Viewed by 1785

Abstract

Cu/ZnO catalysts were synthesized via an impregnation method on an Al₂O₃-ZrO₂ support and modified by the addition of manganese and niobium as promoters. The effect of the selected promoters on the physicochemical properties and performance toward the hydrogenation [...] Read more.

Cu/ZnO catalysts were synthesized via an impregnation method on an Al₂O₃-ZrO₂ support and modified by the addition of manganese and niobium as promoters. The effect of the selected promoters on the physicochemical properties and performance toward the hydrogenation of CO₂ to methanol are presented in this paper. The Mn and Nb promoters improved the reducibility of the catalyst as evidenced by the shifting of the H₂-TPR peaks from 315 °C for the un-promoted catalyst to 284 °C for the Mn- and Nb-promoted catalyst. The catalytic performance in a CO₂ hydrogenation reaction was evaluated in a fixed-bed reactor system at 22.5 bar and 250 °C for 5 h. Amongst the catalysts investigated, the catalyst with equal ratio of Mn and Nb promoters exhibited the smallest particle size of 6.7 nm and highest amount of medium-strength basic sites (87 µmol/g), which resulted in the highest CO₂ conversion (15.9%) and methanol selectivity (68.8%). Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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15 pages, 1850 KiB

Open AccessArticle

Design and Development of a Catalytic Fixed-Bed Reactor for Gasification of Banana Biomass in Hydrogen Production

by Diego Tacuri, Christian Andrade, Paúl Álvarez, Mónica Abril-González, Silvana Zalamea, Verónica Pinos-Vélez, Lourdes Jara and Andres Montero-Izquierdo

Catalysts 2022, 12(4), 395; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12040395 - 01 Apr 2022

Cited by 5 | Viewed by 3711

Abstract

Hydrogen produced from biomass is an alternative energy source to fossil fuels. In this study, hydrogen production by gasification of the banana plant is proposed. A fixed-bed catalytic reactor was designed considering fluidization conditions and a height/diameter ratio of 3/1. Experimentation was carried [...] Read more.

Hydrogen produced from biomass is an alternative energy source to fossil fuels. In this study, hydrogen production by gasification of the banana plant is proposed. A fixed-bed catalytic reactor was designed considering fluidization conditions and a height/diameter ratio of 3/1. Experimentation was carried out under the following conditions: 368 °C, atmospheric pressure, 11.75 g of residual mass of the banana (pseudo-stem), an average particle diameter of 1.84 mm, and superheated water vapor as a gasifying agent. Gasification reactions were performed using a catalyzed and uncatalyzed medium to compare the effectiveness of each case. The catalyst was Ni/Al₂O₃, synthesized by coprecipitation. The gas mixture produced from the reaction was continuously condensed to form a two-phase liquid–gas system. The synthesis gas was passed through a silica gel filter and analyzed online by gas chromatography. To conclude, the results of this study show production of 178 mg of synthesis gas for every 1 g of biomass and the selectivity of hydrogen to be 51.8 mol% when a Ni 2.5% w/w catalyst was used. The amount of CO₂ was halved, and CO was reduced from 3.87% to 0% in molar percentage. Lastly, a simulation of the distribution of temperatures inside the furnace was developed; the modeled behavior is in agreement with experimental observations. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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18 pages, 51040 KiB

Open AccessArticle

Facile Synthesis of Nanosheet-Stacked Hierarchical ZSM-5 Zeolite for Efficient Catalytic Cracking of n-Octane to Produce Light Olefins

by Peng Wang, Xia Xiao, Yutong Pan, Zhen Zhao, Guiyuan Jiang, Zhongdong Zhang, Fanfang Meng, Yuming Li, Xiaoqiang Fan, Lian Kong and Zean Xie

Catalysts 2022, 12(3), 351; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12030351 - 21 Mar 2022

Cited by 7 | Viewed by 2675

Abstract

The development of an effective strategy for synthesizing two-dimensional MFI zeolites has attracted more and more attention. Herein, nanosheet-stacked hierarchical ZSM-5 zeolite was obtained by a seed-assisted hydrothermal synthesis route using a small amount of [C₁₈H₃₇-N⁺(CH₃ [...] Read more.

The development of an effective strategy for synthesizing two-dimensional MFI zeolites has attracted more and more attention. Herein, nanosheet-stacked hierarchical ZSM-5 zeolite was obtained by a seed-assisted hydrothermal synthesis route using a small amount of [C₁₈H₃₇-N⁺(CH₃)₂-C₆H₁₂-N⁺(CH₃)₂-C₆H₁₂]Br₂ (C_18-6-6Br₂) as a zeolite structure-directing agent and triethylamine (TEA) as a zeolite growth modifier. By varying the molar ratio of C_18-6-6Br₂/TEA from 2.5/0 to 2.5/40, the morphologies and textural properties of the resultant HZ5-2.5/x catalysts were finely modulated. By increasing x from 5 to 40, the morphology of the HZ5-2.5/x changed from unilamellar assembly with narrow a–c plane to intertwined nanosheets with wide a–c plane and multilamellar nanosheets with house-of-cards morphology. The thickness of these nanosheets was almost 8–10 nm. In addition, selectivity to light olefins reached 70.7% for the HZ5-2.5/10 catalyst, which was 6.6% higher than that for CZSM-5 (64.1%). Furthermore, the MFI zeolite nanosheets exhibited better anticoking stability within the 60 h reaction time compared to conventional ZSM-5 zeolite, which could be attributed to the short diffusion path and hierarchical porosity. This work will provide valuable insights into the rational design of novel zeolite catalysts for the efficient cracking of hydrocarbons. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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14 pages, 3773 KiB

Open AccessFeature PaperArticle

Insights into a New Formation Mechanism of Robust Cu/SiO₂ Catalysts for Low-Temperature Dimethyl Oxalate Hydrogenation Induced by a Chelating Ligand of EDTA

by Tianyou Li, Ling Lin, Chongchong Chen, Runping Ye, Long Huang, Jinxia Yang, Peng Zhang, Yeyan Qin, Jiankai Cheng and Yuangen Yao

Catalysts 2022, 12(3), 320; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12030320 - 11 Mar 2022

Cited by 2 | Viewed by 2319

Abstract

The Cu/SiO₂ catalyst has been widely used in dimethyl oxalate (DMO) hydrogenation due to its low cost and high efficiency. However, the reaction temperature of DMO hydrogenation is higher than the Hüttig temperature of Cu, and the smaller Cu particles are easier [...] Read more.

The Cu/SiO₂ catalyst has been widely used in dimethyl oxalate (DMO) hydrogenation due to its low cost and high efficiency. However, the reaction temperature of DMO hydrogenation is higher than the Hüttig temperature of Cu, and the smaller Cu particles are easier to agglomerate. Therefore, there is much interest in constructing a catalyst with a small particle size and strong stability. In the present work, the effect of introducing EDTA on Cu/SiO₂ catalysts is systematically investigated. It not only was beneficial to form smaller copper nanoparticles (CuNPs) but also to enhance the stability of Cu species by introducing a suitable amount of EDTA. Furthermore, the surface Cu species were more evenly dispersed, and the number of active sites was increased with the introduction of EDTA; subsequently, the synergistic effect between Cu⁺ and Cu⁰ was enhanced. The best performance of 0.08E-Cu/SiO₂ had been achieved in the DMO hydrogenation to ethylene glycol (EG), and the DMO conversion and EG selectivity reached 99.9% and 97.7%, respectively. Above all, the 0.08E-Cu/SiO₂ catalyst exhibited a high level of stability during the 1200 h life test at 180 °C. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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23 pages, 4757 KiB

Open AccessArticle

Gamma Carbonic Anhydrases from Hydrothermal Vent Bacteria: Cases of Alternating Active Site Due to a Long Loop with Proton Shuttle Residue

by Colleen Varaidzo Manyumwa and Özlem Tastan Bishop

Catalysts 2021, 11(10), 1177; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11101177 - 28 Sep 2021

Cited by 1 | Viewed by 2355

Abstract

Accelerated CO₂ sequestration uses carbonic anhydrases (CAs) as catalysts; thus, there is much research on these enzymes. The γ-CA from Escherichia coli (EcoCA-γ) was the first γ-CA to display an active site that switches between “open” and “closed” states through Zn²⁺ [...] Read more.

Accelerated CO₂ sequestration uses carbonic anhydrases (CAs) as catalysts; thus, there is much research on these enzymes. The γ-CA from Escherichia coli (EcoCA-γ) was the first γ-CA to display an active site that switches between “open” and “closed” states through Zn²⁺ coordination by the proton-shuttling His residue. Here, we explored this occurrence in γ-CAs from hydrothermal vent bacteria and also the γ-CA from Methanosarcina thermophila (Cam) using molecular dynamics. Ten sequences were analyzed through multiple sequence alignment and motif analysis, along with three others from a previous study. Conservation of residues and motifs was high, and phylogeny indicated a close relationship amongst the sequences. All structures, like EcoCA-γ, had a long loop harboring the proton-shuttling residue. Trimeric structures were modeled and simulated for 100 ns at 423 K, with all the structures displaying thermostability. A shift between “open” and “closed” active sites was observed in the 10 models simulated through monitoring the behavior of the His proton-shuttling residue. Cam, which has two Glu proton shuttling residues on long loops (Glu62 and Glu84), also showed an active site switch affected by the first Glu proton shuttle, Glu62. This switch was thus concluded to be common amongst γ-CAs and not an isolated occurrence. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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Review

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24 pages, 7738 KiB

Open AccessEditor’s ChoiceReview

Achievements and Perspectives in Metal–Organic Framework-Based Materials for Photocatalytic Nitrogen Reduction

by Linkun Fan, Qin Yu, Jiazhen Chen, Usman Khan, Xusheng Wang and Junkuo Gao

Catalysts 2022, 12(9), 1005; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12091005 - 06 Sep 2022

Cited by 12 | Viewed by 2697

Abstract

Metal–organic frameworks (MOFs) are coordination polymers with high porosity that are constructed from molecular engineering. Constructing MOFs as photocatalysts for the reduction of nitrogen to ammonia is a newly emerging but fast-growing field, owing to MOFs’ large pore volumes, adjustable pore sizes, controllable [...] Read more.

Metal–organic frameworks (MOFs) are coordination polymers with high porosity that are constructed from molecular engineering. Constructing MOFs as photocatalysts for the reduction of nitrogen to ammonia is a newly emerging but fast-growing field, owing to MOFs’ large pore volumes, adjustable pore sizes, controllable structures, wide light harvesting ranges, and high densities of exposed catalytic sites. They are also growing in popularity because of the pristine MOFs that can easily be transformed into advanced composites and derivatives, with enhanced catalytic performance. In this review, we firstly summarized and compared the ammonia detection methods and the synthetic methods of MOF-based materials. Then we highlighted the recent achievements in state-of-the-art MOF-based materials for photocatalytic nitrogen fixation. Finally, the summary and perspectives of MOF-based materials for photocatalytic nitrogen fixation were presented. This review aims to provide up-to-date developments in MOF-based materials for nitrogen fixation that are beneficial to researchers who are interested or involved in this field. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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22 pages, 5090 KiB

Open AccessFeature PaperReview

Advances in Enhancing the Stability of Cu-Based Catalysts for Methanol Reforming

by Runping Ye, Shuwei Xiao, Qinghua Lai, Dashan Wang, Yuanyuan Huang, Gang Feng, Rongbin Zhang and Tao Wang

Catalysts 2022, 12(7), 747; https://0-doi-org.brum.beds.ac.uk/10.3390/catal12070747 - 07 Jul 2022

Cited by 19 | Viewed by 2945

Abstract

The advent of fuel cells has led to a series of studies on hydrogen production. As an excellent hydrogen carrier, methanol can be used for reforming to produce hydrogen. Copper-based catalysts have been widely used in methanol reforming due to their high catalytic [...] Read more.

The advent of fuel cells has led to a series of studies on hydrogen production. As an excellent hydrogen carrier, methanol can be used for reforming to produce hydrogen. Copper-based catalysts have been widely used in methanol reforming due to their high catalytic activity and low-cost preparation. However, copper-based catalysts have been subjected to poor stability due to spontaneous combustion, sintering, and deactivation. Thus, the research on the optimization of copper-based catalysts is of great significance. This review analyzes several major factors that affect the stability of copper-based catalysts, and then comments on the progress made in recent years to improve the catalytic stability through various methods, such as developing preparation methods, adding promoters, and optimizing supports. A large number of studies have shown that sintering and carbon deposition are the main reasons for the deactivation of copper-based catalysts. It was found that the catalysts prepared by the modified impregnation method exhibit higher catalytic activity and stability. For the promoters and supports, it was also found that the doping of metal oxides such as MgO and bimetallic oxides such as CeO₂-ZrO₂ as the support could present better catalytic performance for the methanol reforming reaction. It is of great significance to discover some new materials, such as copper-based spinel oxide, with a sustained-release catalytic mechanism for enhancing the stability of Cu-based catalysts. However, the interaction mechanism between the metal and the support is not fully understood, and the research of some new material copper-based catalysts in methanol reforming has not been fully studied. These are the problems to be solved in the future. Full article

(This article belongs to the Special Issue Current State-of-the-Art of Catalysts for Energy and Environmental Applications)

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