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Non-critical Element- and Non-critical Loading of Critical Element-Based Catalysts for...
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Non-critical Element- and Non-critical Loading of Critical Element-Based Catalysts for Environmentally Friendly Catalytic Processes

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 13257

Special Issue Editor

Prof. Dr. Maria Olea, FRSC

E-Mail Website
Guest Editor
Institute of Continuing Education, University of Cambridge, Madingley Hall, Cambridge CB23 8AQ, UK
Interests: heterogeneous catalysis applied to environmentally friendly processes; scale-up of catalysts; scale-down of reactors (microreactors)

Special Issue Information

Dear colleagues,

Modern society has an ever-increasing demand for environmentally friendly catalytic processes, either for clean manufacturing of chemicals or for renewable energy production, elimination of environmental pollutants from air, water and soil or for waste conversion into useful products. Although noble metal-based catalysts have proven to be very efficient for all these environmentally friendly catalytic processes, due to their scarcity and cost, alternative catalytic technologies are being developed based on either their non-critical loadings or non-critical elements. This Special Issue is focused on “Non-critical Element and Non-critical Loading of Critical Element-Based Catalysts for Environmentally Friendly Catalytic Processes” with the aim to present the most recent and innovative scientific results in this field, regarding all aspects of design and formulation, preparation, characterisation, scale-up and engineering aspects for commercially applications.

Prof. Dr. Maria Olea, FRSC
Guest Editor

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

  • Non-critical element catalysts
  • Non-critical loading of critical element catalysts, preparation
  • characterisation
  • scale-up
  • catalytic reactors and microreactors
  • design
  • formulation

Published Papers (4 papers)

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Research

27 pages, 8973 KiB  
Article
Elimination of Indoor Volatile Organic Compounds on Au/SBA-15 Catalysts: Insights into the Nature, Size, and Dispersion of the Active Sites and Reaction Mechanism
by Emmanuel Iro, Hiroko Ariga-Miwa, Takehiko Sasaki, Kiyotaka Asakura and Maria Olea
Catalysts 2022, 12(11), 1365; https://doi.org/10.3390/catal12111365 - 04 Nov 2022
Cited by 1 | Viewed by 2230
Abstract
Gold catalysts, with different particle sizes ranging from 19 to 556 Å, and supported on SBA-15 mesoporous silica, were prepared by using deposition-precipitation, co-precipitation, and impregnation methods. All samples were characterised by TEM, EXAFS, XPS, XRD, CFR (Continuous Flow Reactor), and TPR. The [...] Read more.
Gold catalysts, with different particle sizes ranging from 19 to 556 Å, and supported on SBA-15 mesoporous silica, were prepared by using deposition-precipitation, co-precipitation, and impregnation methods. All samples were characterised by TEM, EXAFS, XPS, XRD, CFR (Continuous Flow Reactor), and TPR. The sample which proved to have the highest activity was characterised by TAP (Temporal Analysis of Products) as well. XPS, wide-angle XRD, EXAFS, and H2-TPR measurements and data analysis confirmed that gold was present as Au0 only on all samples. The size of the Au nanoparticle was determined from TEM measurements and confirmed through wide-angle XRD measurements. EXAFS measurements showed that as the Au-Au coordination number decreased the Au-Au bond length decreased. TEM data analysis revealed a dispersion range from 58% (for the smallest particle size) to 2% (for the highest particle size). For Au particles’ sized lower that 60 Å, the Au dispersion was determined using a literature correlation between the dispersion and EXAFS Au-Au coordination number, and was in good agreement with the dispersion data obtained from TEM. The Au dispersion decreased as the particle size increased. CFR experiments validated the relationship between the size of the gold particles in a sample and the sample’s catalytic activity towards acetone oxidation. The lowest temperature for the acetone 100% conversion, i.e., 250 °C, was observed over the reduced catalyst sample with the smallest particle size. This sample not only showed the highest catalytic activity towards acetone conversion, but, at the same time, showed high reaction stability, as catalyst lifetime tests, performed for 25 h in a CFR at 270 °C for the as-synthesised sample, and at 220 °C for the reduced sample, have confirmed. TAP (Temporal Analysis of Products) measurements and data analysis confirmed a weak competitive adsorption of acetone and oxygen over the Au/SBA-15 sample. Based on TAP data, a combination of Eley–Rideal and Langmuir–Hinshelwood mechanisms for acetone complete oxidation was proposed. Full article
(This article belongs to the Special Issue Non-critical Element- and Non-critical Loading of Critical Element-Based Catalysts for Environmentally Friendly Catalytic Processes)
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12 pages, 6718 KiB  
Article
Catalytic Degradation of Chitosan by Supported Heteropoly Acids in Heterogeneous Systems
by Hang Zhang, Zhipeng Ma, Yunpeng Min, Huiru Wang, Ru Zhang, Xuecheng Zhang and Yimin Song
Catalysts 2020, 10(9), 1078; https://doi.org/10.3390/catal10091078 - 18 Sep 2020
Viewed by 1914
Abstract
Several kinds of composite materials with phosphotungstic acid (PTA) as the catalyst were prepared with activated carbon as support, and their structures were characterized. According to the Box–Behnken central combination principle, the mathematical model of the heterogeneous system is established. Based on the [...] Read more.
Several kinds of composite materials with phosphotungstic acid (PTA) as the catalyst were prepared with activated carbon as support, and their structures were characterized. According to the Box–Behnken central combination principle, the mathematical model of the heterogeneous system is established. Based on the single-factor experiments, the reaction temperature, the reaction time, the amount of hydrogen peroxide and the loading capacity of PTA were selected as the influencing factors to study the catalyzed oxidation of hydrogen peroxide and degradation of high molecular weight chitosan. The results of IR showed that the catalyst had a Keggin structure. The results of the mercury intrusion test showed that the pore structure of the supported PTA catalyst did not change significantly, and with the increase of PTA loading, the porosity and pore volume decreased regularly, which indicated that PTA molecules had been absorbed and filled into the pore of activated carbon. The results of Response Surface Design (RSD) showed that the optimum reaction conditions of supported PTA catalysts for oxidative degradation of high molecular weight chitosan by hydrogen peroxide were as follows: reaction temperature was 70 ℃, reaction time was 3.0 h, the ratio of hydrogen peroxide to chitosan was 2.4 and the catalyst loading was 30%. Under these conditions, the yield and molecular weight of water-soluble chitosan were 62.8% and 1290 Da, respectively. The supported PTA catalyst maintained high catalytic activity after three reuses, which indicated that the supported PTA catalyst had excellent catalytic activity and stable performance compared with the PTA catalyst. Full article
(This article belongs to the Special Issue Non-critical Element- and Non-critical Loading of Critical Element-Based Catalysts for Environmentally Friendly Catalytic Processes)
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23 pages, 7186 KiB  
Article
Micro-Reactor System for Complete Oxidation of Volatile Organic Compounds
by Sunday Odiba, Maria Olea, Takehiko Sasaki, Emmanuel Iro, Simon Hodgson, Adam Adgar and Paul Russell
Catalysts 2020, 10(8), 846; https://doi.org/10.3390/catal10080846 - 28 Jul 2020
Cited by 4 | Viewed by 4473
Abstract
Based on previous Computational Fluid Dynamics (CFD) design results, an 11 channel microreactor of dimensions (0.5 mm × 0.5 mm × 100 mm) (width × depth × length) and optimal manifold geometry was fabricated, coated with a newly-developed Au/SBA-15 catalyst and then integrated [...] Read more.
Based on previous Computational Fluid Dynamics (CFD) design results, an 11 channel microreactor of dimensions (0.5 mm × 0.5 mm × 100 mm) (width × depth × length) and optimal manifold geometry was fabricated, coated with a newly-developed Au/SBA-15 catalyst and then integrated in an experimental rig specifically built for this research. Propane (as model volatile organic compound) oxidation experiments were conducted at three different flow velocities, 12.5, 15.4 and 17.5 m/min, respectively, at six temperatures, 150, 200, 225, 250, 275, and 300 °C, respectively. The catalyst was prepared by one-pot sol-gel synthesis of SBA-15 with MPTMS (3-mercaptopropyl-trimethoxy-silane) before loading with HAuCl4 gold precursor and then characterized by SEM/EDX, TEM and wide angle XRD. A novel catalyst coating technique was developed, using airbrush (0.3 nozzle) to spray a catalyst slurry into the microchannels that produced a thin, firm and uniform layer of Au/SBA-15 catalyst coating inside the microreactor. The experimental measurements revealed that propane conversion increased as the flow feed rates decreased and increased with increasing temperatures in the reactor. For the built microreactor and for the flows and temperatures set, the combustion of propane was possible with measurable conversions and reasonable reactor stability, the performance of the catalyst appeared to be central to the satisfactory operation of the reactor. Full article
(This article belongs to the Special Issue Non-critical Element- and Non-critical Loading of Critical Element-Based Catalysts for Environmentally Friendly Catalytic Processes)
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14 pages, 6014 KiB  
Article
The Distinctive Effects of Glucose-Derived Carbon on the Performance of Ni-Based Catalysts in Methane Dry Reforming
by UPM Ashik, Shusaku Asano, Shinji Kudo, Doan Pham Minh, Srinivas Appari, Einaga Hisahiro and Jun-ichiro Hayashi
Catalysts 2020, 10(1), 21; https://doi.org/10.3390/catal10010021 - 23 Dec 2019
Cited by 5 | Viewed by 3516
Abstract
This study aimed to investigate the effect of carbon derived from glucose (C) on the physicochemical characteristics and catalytic activity of Ni, supported over SiO2, ZSM-5, and TiO2 in methane dry reforming. Among the Ni catalysts without C, Ni/SiO2 [...] Read more.
This study aimed to investigate the effect of carbon derived from glucose (C) on the physicochemical characteristics and catalytic activity of Ni, supported over SiO2, ZSM-5, and TiO2 in methane dry reforming. Among the Ni catalysts without C, Ni/SiO2 exhibited the highest CH4-CO2 conversion and stability at all experimented temperatures. On the other hand, the C-incorporated catalysts prepared by glucose impregnation, followed by pyrolysis, showed dissimilar performances. C improved the stability of Ni/SiO2 in the reforming at 650 °C and 750 °C and increased the CH4 and CO2 conversion to the level close to the thermodynamic equilibrium at 850 °C. However, this element did not substantially affect the activity of Ni/ZSM-5 and exerted a retarding effect on Ni/TiO2. Characterizations with H2-TPD, XRD, EXAFS, and STEM-EDS revealed that the different influences of C by the supports were attributed to the extent of metal dispersion and metal-support interaction. Full article
(This article belongs to the Special Issue Non-critical Element- and Non-critical Loading of Critical Element-Based Catalysts for Environmentally Friendly Catalytic Processes)
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