Recent Advances and Strategies in the Development of Sustainable Metal Catalysts for Energy, Environment and Generation of High-Value Products

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalysis for Sustainable Energy".

Deadline for manuscript submissions: closed (20 March 2024) | Viewed by 9170

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Guest Editor
Department of Chemistry, Università degli Studi di Milano, Milano, Italy
Interests: heterogenous catalysis; interfaces and surfaces; material characterization; circular economy; physical chemistry
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Chemistry, Università degli Studi di Milano, Milano, Italy
Interests: heterogenous catalysis; photocatalysis; interfaces and surfaces; material characterization; environmental protection; industrial chemistry; physical chemistry

Special Issue Information

Dear Colleagues,

It is our pleasure to invite you to submit your papers to the Special Issue “Recent Advances and Strategies in the Development of Sustainable Metal Catalysts for Energy, Environment and Generation of High-Value Products”.

Heterogeneous catalysis is at the core of most industrial processing procedures for the production of energy or/and high-value products. Due to the dramatic increase in the worldwide population and daily activities of society, meeting the worldwide need for energy and related products has become even more challenging. Therefore, enhancing productibility through the design of highly effective yet sustainable catalysts is urgently required. Meta-based catalysts are a significantly attractive option for running a wide range of catalytic processes. To select a catalyst for a given application, several factors should be considered, with the ideal catalyst having a high catalytic performance, low cost, nontoxic nature and highly physical/chemical stability, wide availability, excellent recyclability, and lower energy consumption and nontoxic gas production during synthesis, with an ecofriendly end-of-life destination.

This Special Issue aims to discuss the recent advances in designing innovative nontoxic sustainable metal-based catalysts for energy production, high-value product generation, and environmental remediation.

Topics of interest include, but are not limited to, the following:

  • Current status and challenges in the green synthesis of cheap and ecofriendly metal-based catalysts;
  • Updates and perspectives on techno-economics and life cycle assessment of metal-based catalysts;
  • Development of low-metal loading catalysts;
  • Design of metal catalysts for the recycling and valorization of waste materials;
  • Upcycling of metal-containing waste materials into catalysts;
  • Application of metal-based catalysts for energy production and environmental remediation;
  • Biomass conversion into highly value products via metal-based catalysts: mechanistic and challenges;
  • Deactivation mechanisms of metal-based catalysts and approaches to control it.

Dr. Sebastiano Campisi
Dr. Melissa Greta Galloni
Dr. Ridha Djellabi
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • catalysis
  • metal catalysts
  • photocatalysis
  • electrocatalysis
  • energy production
  • life cycle
  • sustainability
  • environmental remediation

Published Papers (5 papers)

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Research

19 pages, 21509 KiB  
Article
Ru/Attapulgite as an Efficient and Low-Cost Ammonia Decomposition Catalyst
by Qingfeng Teng, Junkang Sang, Guoxin Chen, Haoliang Tao, Yunan Wang, Hua Li, Wanbing Guan, Changsheng Ding, Fenghua Liu and Liangzhu Zhu
Catalysts 2024, 14(3), 197; https://doi.org/10.3390/catal14030197 - 16 Mar 2024
Viewed by 1255
Abstract
On-site hydrogen generation from ammonia decomposition is a promising technology to address the challenges of direct transportation and storage of hydrogen. The main problems with the existing support materials for ammonia decomposition catalysts are their high cost and time-consuming preparation process. In this [...] Read more.
On-site hydrogen generation from ammonia decomposition is a promising technology to address the challenges of direct transportation and storage of hydrogen. The main problems with the existing support materials for ammonia decomposition catalysts are their high cost and time-consuming preparation process. In this work, ammonia decomposition catalysts consisting of in situ-formed nano-Ru particles supported on a naturally abundant mineral fiber, attapulgite (ATP), were proposed and studied. Also, 1 wt.% Ru was uniformly dispersed and anchored onto the surface of ATP fibers via the chemical method. We found that the calcination temperatures of the ATP support before the deposition of Ru resulted in little difference in catalytic performance, while the calcination temperatures of the 1Ru/ATP precursor were found to significantly influence the catalytic performance. The prepared 1 wt.% Ru/ATP catalyst (1Ru/ATP) without calcination achieved an ammonia conversion efficiency of 51% at 500 °C and nearly 100% at 600 °C, with the flow rate of NH3 being 10 sccm (standard cubic centimeter per minute). A 150 h continuous test at 600 °C showed that the 1Ru/ATP catalyst exhibited good stability with a degradation rate of about 0.01% h−1. The 1Ru/ATP catalyst was integrated with proton ceramic fuel cells (PCFCs). We reported that PCFCs at 650 °C offered 433 mW cm−2 under H2 fuel and 398 mW cm−2 under cracked NH3 fuel. The overall results suggest low-level Ru-loaded ATP could be an attractive, low-cost, and efficient ammonia decomposition catalyst for hydrogen production. Full article
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22 pages, 5375 KiB  
Article
Feed Effects on Water–Gas Shift Activity of M/Co3O4-ZrO2 (M = Pt, Pd, and Ru) and Potassium Role in Methane Suppression
by Satyapaul A. Singh, Yaddanapudi Varun, Priyanka Goyal, I. Sreedhar and Giridhar Madras
Catalysts 2023, 13(5), 838; https://doi.org/10.3390/catal13050838 - 04 May 2023
Cited by 1 | Viewed by 1510
Abstract
Water–gas shift (WGS) is an industrial process to tackle CO abatement and H2 upgradation. The syngas (CO and H2 mixture) obtained from steam or dry reformers often has unreacted (from dry reforming) or undesired (from steam reforming) CO2, which [...] Read more.
Water–gas shift (WGS) is an industrial process to tackle CO abatement and H2 upgradation. The syngas (CO and H2 mixture) obtained from steam or dry reformers often has unreacted (from dry reforming) or undesired (from steam reforming) CO2, which is subsequently sent to downstream WGS reactor for H2 upgradation. Thus, industrial processes must deal with CO2 and H2 in the reformate feed. Achieving high CO2 or H2 selectivities become challenging due to possible CO and CO2 methanation reactions, which further increases the separation costs to produce pure H2. In this study, M/Co3O4-ZrO2 (M = Ru, Pd and Pt) catalysts were prepared using sonochemical synthesis. The synthesized catalysts were tested for WGS activity under three feed conditions, namely, Feed A (CO and steam), Feed B (CO, H2 and steam) and Feed C (CO, H2, CO2 and steam). All the catalysts gave zero methane selectivity under Feed A conditions, whereas the methane selectivity was significant under Feed B and C conditions. Among all catalysts, PtCZ was found to be the best performing catalyst in terms of CO conversion and CO2 selectivity. However, it still suffered with low but significant methane selectivity. This best performing catalyst was further modified with an alkali component, potassium to suppress undesirable methane selectivity. All the catalysts were well characterized with BET, SEM, TEM to confirm the structural properties and effective doping of the noble metals. Additionally, the apparent activation energies were obtained to showcase the best catalyst. Full article
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16 pages, 4033 KiB  
Article
Impact of Annealing on ZrO2 Nanotubes for Photocatalytic Application
by Safa Jemai, Lotfi Khezami, Kaouther Gueddana, Khaled Trabelsi, Anouar Hajjaji, Mosbah Amlouk, Bernabé Mari Soucase, Brahim Bessais and Sami Rtimi
Catalysts 2023, 13(3), 558; https://doi.org/10.3390/catal13030558 - 10 Mar 2023
Cited by 4 | Viewed by 1541
Abstract
This work aims to study the structural, optical, and photocatalytic properties of ZrO2 nanotubes (NTs) that have been synthesized using the electrochemical anodization method. The structural and morphological characteristics of unannealed and annealed (400 °C, 500 °C, and 700 °C) ZrO2 [...] Read more.
This work aims to study the structural, optical, and photocatalytic properties of ZrO2 nanotubes (NTs) that have been synthesized using the electrochemical anodization method. The structural and morphological characteristics of unannealed and annealed (400 °C, 500 °C, and 700 °C) ZrO2 NTs were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Details of the structural and morphological results are depicted to clarify the effect of annealing temperature on the NTs. Furthermore, the reflectivity and photoluminescence of ZrO2 NTs were found to depend on the annealing temperature. The resulting bandgap values were 3.1 eV for samples annealed at 400 °C and 3.4 eV for samples annealed at 550 and 700 °C. Thus, amorphous and annealed ZrO2 NTs were tested in terms of their photocatalytic degradation of Black Amido (BA) dye. Samples annealed at 400 °C exhibited 85.4% BA degradation within 270 min compared to 77.5% for samples annealed at 550 °C and 70.2% for samples annealed at 700 °C. The anodized ZrO2 NTs that were annealed at 400 °C showed the coexistence of tetragonal and monoclinic crystalline phases and exhibited the fastest photocatalytic performance against the BA dye. This photocatalytic behavior was correlated to the crystalline phase transformation and the structural defects seen in anodized ZrO2. Full article
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18 pages, 5751 KiB  
Article
The Efficiency of Carbon Conversion and Hydrogen Production from Tar Steam Reforming of Biomass Using Ni-Based Catalysts with Alkaline Earth Promoters
by Afizah Alir, Tuan Amran Tuan Abdullah, Anwar Johari, Mohamed Yusuf Mohamud, Melissa Low Phey Phey, Walid Nabgan, Francisco Medina and Muhammad Ikram
Catalysts 2023, 13(3), 472; https://doi.org/10.3390/catal13030472 - 23 Feb 2023
Cited by 2 | Viewed by 1949
Abstract
H2 production can be used as a clean and renewable energy source for various applications, including fuel cells, internal combustion engines, and chemical production. Using nickel-based catalysts for steam reforming biomass tar presents challenges related to catalyst deactivation, poisoning, heterogeneous composition, high [...] Read more.
H2 production can be used as a clean and renewable energy source for various applications, including fuel cells, internal combustion engines, and chemical production. Using nickel-based catalysts for steam reforming biomass tar presents challenges related to catalyst deactivation, poisoning, heterogeneous composition, high process temperatures, and gas impurities. To overcome these challenges, adopting a nickel-based catalyst with selected oxide support and MgO and CaO promoter is a promising approach for improving the efficiency and sustainability of steam reforming for hydrogen production. The majority of studies conducted to date have focused on the steam reforming of particular tar compounds, most commonly benzene, phenol, toluene, or naphthalene, over a range of support catalysts. However, the actual biomass tar composition is complex, and each component impacts how well steam reforming works. In this research, a multi-compound biomass tar model including phenol, toluene, naphthalene, and pyrene underwent a steam reforming process. Various types with 10 wt.% of nickel-based catalysts were generated by the co-impregnation technique, which included 90 wt.% different oxide supports (Al2O3, La2O3, and ZrO2) and 10 wt.% of combination alkaline oxide earth promoters (MgO and CaO). Thermogravimetric analysis, Brunauer–Emmett–Teller (BET) method, N2 physisorption, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (CO2-TPD), and X-ray diffraction (XRD) of ni-based catalyst characterized physiochemical properties of the prepared catalyst. The reaction temperature used for steam reforming was 800 °C, an S/C ratio of 1, and a GHSV of 13,500 h−1. Ni/La2O3/MgO/CaO (NiLaMgCa) produced the most carbon to-gas conversion (86.27 mol%) and H2 yield (51.58 mol%) after 5 h of reaction compared to other catalysts tested in this study. Additionally, the filamentous carbon coke deposited on the spent catalyst of NiLaMgCa does not impact the catalyst activity. NiLaMgCa was the best catalyst compared to other catalysts investigated, exhibiting a stable and high catalytic performance in the steam reforming of gasified biomass tar. In conclusion, this study presents a novel approach by adding a combination of MgO and CaO promoters to a ni-based catalyst with various oxide supports, strengthening the metal-support interaction and improving the acid-base balance of the catalyst surface. The mesoporous structure and active phase (metallic Ni) were successfully developed. This can lead to an increase in the conversion of tar to H2 yield gas and a decrease in the production of undesired byproducts, such as CH4 and CO. Full article
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18 pages, 3000 KiB  
Article
Direct Synthesis of Dimethyl Ether from CO2 Hydrogenation over Core-Shell Nanotube Bi-Functional Catalyst
by Mohamed Yusuf Mohamud, Tuan Amran Tuan Abdullah, Arshad Ahmad, Muhammad Ikram, Afizah Alir, Melissa Low Phey Phey and Walid Nabgan
Catalysts 2023, 13(2), 408; https://doi.org/10.3390/catal13020408 - 14 Feb 2023
Cited by 1 | Viewed by 2039
Abstract
Directly synthesising dimethyl ether (DME) from CO2 hydrogenation is a promising technique for efficiently utilising CO2 as a feedstock to produce clean fuel. The main challenges in this process are the low CO2 conversion and DME selectivity of the catalyst [...] Read more.
Directly synthesising dimethyl ether (DME) from CO2 hydrogenation is a promising technique for efficiently utilising CO2 as a feedstock to produce clean fuel. The main challenges in this process are the low CO2 conversion and DME selectivity of the catalyst and its deactivation over time due to sintering, aggregation, coke formation, and water adsorption. This study aimed to develop a dual-functional, halloysite nanotube-supported CuZnO-PTA catalyst with a core-shell structure and investigate the effects of the active site mass ratio CuZnO/PTA on CO2 conversion and DME selectivity. A dual-functional core-shell mesopores halloysite nanotube (HNT) catalyst was developed, and both active sites were co-hosted on one support. The co-impregnation method was used to synthesise CuZnO and 12-phosphotungstic acids (PTA) that were then supported by a mesoporous core-shell (HNT). BET surface area, N2 physisorption, FE-SEM, SEM, XRD, H2-TPR, and NH3-TPD of the core-shell catalyst characterised physio-chemical properties of the prepared hybrid catalyst. The experimental results showed that the synthesised CuZn-PTA@HNT core-shell bifunctional catalyst was promising; the CO2 conversion was almost the same for all four catalysts, with an average of 22.17%, while the DME selectivity reached 68.9%. Furthermore, the effect of both active sites on the hybrid catalyst was studied, and the metal Cu wt% mass ratio loading was not significant. In contrast, the PTA acid sites positively affected DME selectivity; they also showed an excellent tolerance towards the water generated in the methanol dehydration reaction. In addition, the effect of the temperature and reusability of the CZ-PTA@HNT catalyst has also been investigated, and the results show that increasing the temperature improves CO2 conversion but decreases DME selectivity. A temperature of less than 305 °C is a good compromise between CO2 conversion and DME selectivity, and the catalyst also showed good stability and continuous activity/stability over five consecutive cycles. In conclusion, this study presents a novel approach of using a core-shell halloysite nanotube-supported CuZnO-PTA catalyst to directly synthesise dimethyl ether (DME) from CO2 hydrogenation which exhibits promising results in terms of CO2 conversion and DME selectivity. Full article
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