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Catalysts
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Fluidizable Catalysts for Novel Chemical Processes
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Fluidizable Catalysts for Novel Chemical Processes

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

Deadline for manuscript submissions: closed (17 July 2024) | Viewed by 5174

Special Issue Editors

Prof. Dr. Hugo de Lasa

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Guest Editor
Chemical Reactor Engineering Centre (CREC), Faculty of Engineering, Western University, London, ON N6A 5B9, Canada
Interests: catalysis; photocatalysis; reaction engineering; fluidized bed reactors
Special Issues, Collections and Topics in MDPI journals
Dr. Nicolas Brauer

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Guest Editor
Chemical Reactor Engineering Centre, Department of Chemical and Biochemical Engineering, University of Western Ontario, London, ON N6A 5B9, Canada
Interests: fluidization; reaction engineering; chemical processes; machine learning; environmental engineering

Special Issue Information

Dear Colleagues,

We would like to warmly invite you to contribute to the Special Issue of Catalysts entitled "Fluidizable Catalysts for Novel Chemical Processes".

Fluidizable catalysts offer unique opportunities to develop valuable new green and environmentally friendly catalytic chemical processes. Fluidizable catalysts frequently display the outstanding property of not being influenced in their performance, via intraparticle mass transport and heat transport processes, inside the catalyst particles. Thus, they provide a much more reliable catalytic performance than traditional non-fluidized bed processes. Fluidizable catalysts can be employed to degrade harmful and toxic pollutants. They can also be the basis of new processes, achieving chemical changes with lower energy demands, and consequently reduced environmental impact (e.g., CO2 emissions). Another promising application of fluidizable catalysts is hydrogen production. The generated hydrogen can be used as a unique vector, able to make a source of green energy available to isolated towns and agricultural communities around the world.

Despite their promise, there are still major pending issues to be considered for successful catalyst and catalytic process unit scale-up. These issues can be addressed using a new generation of industrial-scale fluidized bed systems, with high feedstock throughputs, such as riser or downer catalytic units. It is anticipated that these low-particle-density fluidized beds can be engineered with closely controlled reaction times and reaction conditions (reactant partial pressures, temperatures, catalyst/reactant ratios), allowing catalytic reactions to take place, as expected and determined by reaction mechanisms and intrinsic kinetics.

The aim of this Special Issue is to report recent progress on the following key topics on fluidized catalysts: (a) their synthesis, characterization and development; (b) their kinetics and reaction mechanisms; (c) the observed conversion and selectivity; and (d) the new lean fluidized catalytic reactor designs, with high reactant throughputs.

We are presently accepting cutting-edge research papers, critical reviews and short communications. Papers can be supported with supplementary materials, such as videos and additionally provided data. We are looking forward to receiving your valuable research contribution.

Prof. Dr. Hugo de Lasa
Dr. Nicolas Torres Brauer
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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

  • catalysts
  • fluidizable catalysts
  • fluidizable catalyst synthesis
  • fluidizable catalyst characterization
  • fluidizable catalyst performance
  • fluidizable catalyst kinetics

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Published Papers (5 papers)

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Research

18 pages, 2366 KiB  
Article
Dependence of the Fluidizing Condition on Operating Parameters for Sorption-Enhanced Methanol Synthesis Catalyst and Adsorbent
by Simona Renda, Javier Lasobras, Jaime Soler, Javier Herguido and Miguel Menéndez
Catalysts 2024, 14(7), 432; https://doi.org/10.3390/catal14070432 - 7 Jul 2024
Viewed by 728
Abstract
The fluidization of two different solids was investigated by varying the temperature and pressure conditions and the fluidizing gas. The solids are a novel catalyst and a water sorbent that could be used to perform sorption-enhanced methanol synthesis; the operating conditions were selected [...] Read more.
The fluidization of two different solids was investigated by varying the temperature and pressure conditions and the fluidizing gas. The solids are a novel catalyst and a water sorbent that could be used to perform sorption-enhanced methanol synthesis; the operating conditions were selected accordingly to this process. The aim of this investigation was to find an expression for predicting the minimum fluidization conditions of a methanol synthesis catalyst and an adsorbent in the presence of their process stream and operating conditions. The findings of this study highlighted how umf (STP) decreases with a rise in temperature and increases with a rise in pressure, according to other works in the literature with different solids. Furthermore, the type of gas was found to influence the minimum fluidization velocity significantly. The experimental results agreed well with a theoretical expression of the minimum fluidization velocity adjusted for temperature, pressure, and viscosity. The choice of the expression for viscosity calculation in the case of gas mixtures was found to be of key importance. These results will be useful for researchers aiming to calculate the minimum fluidization velocity of a catalyst or other solids under reaction conditions using results obtained at ambient conditions with air or inert gas. Full article
(This article belongs to the Special Issue Fluidizable Catalysts for Novel Chemical Processes)
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17 pages, 3523 KiB  
Article
A Preliminary Assessment of Sorption-Enhanced Methanol Synthesis in a Fluidized Bed Reactor with Selective Addition/Removal of the Sorbent
by Miguel Menéndez, Raúl Ciércoles, Javier Lasobras, Jaime Soler and Javier Herguido
Catalysts 2024, 14(7), 409; https://doi.org/10.3390/catal14070409 - 28 Jun 2024
Viewed by 557
Abstract
Methanol synthesis from CO2 can be made in the presence of a sorbent to increase the achievable yield. If the fresh sorbent is continuously fed to a fluidized bed and separated from the catalyst bed by segregation, a steady-state operation can be [...] Read more.
Methanol synthesis from CO2 can be made in the presence of a sorbent to increase the achievable yield. If the fresh sorbent is continuously fed to a fluidized bed and separated from the catalyst bed by segregation, a steady-state operation can be achieved. The objective of the present work is to provide insight on the suitable operating conditions for such a fluidized bed reactor system. For this, a conventional CuO/ZnO/Al2O3 was selected as the catalyst, and the SiOLITE® zeolite was selected as the sorbent. Different particle sizes were used to be tested in various proportions to perform the fluidized bed segregation study. The fluid dynamics and segregation of the catalyst–sorbent binary mixtures were the most critical points in the development of this proof of concept. A good bed segregation with a mixing index of 0.31 was achieved. This fact favors the correct operation of the system with the continuous addition of adsorbent, which had hardly any catalyst losses during the tests carried out, achieving a loss of 0.005 g/min under optimal conditions. Continuous feeding and removal of sorbent with a low loss of catalyst was observed. Reactor simulations with MATLAB provided promising results, indicating that the addition of sorbent considerably improves the methanol yield under some operating conditions. This makes it more viable for industrial scaling, since it allows us to considerably reduce the pressure used in the methanol synthesis process or to increase the yield per step, reducing the recirculation of unconverted reactants. Full article
(This article belongs to the Special Issue Fluidizable Catalysts for Novel Chemical Processes)
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16 pages, 7015 KiB  
Article
A Novel SnO2/ZnFe2O4 Magnetic Photocatalyst with Excellent Photocatalytic Performance in Rhodamine B Removal
by Yu Hao, Yi Xiao, Xiuzhu Liu, Jiawei Ma, Yuan Lu, Ziang Chang, Dayong Luo, Lin Li, Qi Feng, Longjun Xu and Yongkui Huang
Catalysts 2024, 14(6), 350; https://doi.org/10.3390/catal14060350 - 29 May 2024
Viewed by 814
Abstract
In this study, we prepared the SnO2/ZnFe2O4 (SZ) composite magnetic photocatalyst via a two-step hydrothermal method. Structural and performance analyses revealed that SZ-5 with a ZnFe2O4 mass ratio of 5% (SZ-5) exhibited optimal photocatalytic activity, [...] Read more.
In this study, we prepared the SnO2/ZnFe2O4 (SZ) composite magnetic photocatalyst via a two-step hydrothermal method. Structural and performance analyses revealed that SZ-5 with a ZnFe2O4 mass ratio of 5% (SZ-5) exhibited optimal photocatalytic activity, achieving a 72.6% degradation rate of Rhodamine B (RhB) solution within 120 min. SZ-5 consisted of irregular nano blocks of SnO2 combined with spherical nanoparticles of ZnFe2O4, with a saturated magnetization intensity of 1.27 emu/g. Moreover, the specific surface area of SnO2 loaded with ZnFe2O4 increased, resulting in a decreased forbidden bandwidth and expanded light absorption range. The construction of a Z-type heterojunction structure between SnO2 and ZnFe2O4 facilitated the migration of photogenerated charges, reduced the recombination rate of electron-hole pairs, and enhanced electrical conductivity. During the photocatalytic reaction, RhB was degraded by·OH, O2−, and h+, in which O2− played a major role. Full article
(This article belongs to the Special Issue Fluidizable Catalysts for Novel Chemical Processes)
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29 pages, 9793 KiB  
Article
Conversion of Biomass-Derived Tars in a Fluidized Catalytic Post-Gasification Process
by Floria Rojas Chaves, Nicolas Torres Brauer, Cindy Torres and Hugo de Lasa
Catalysts 2024, 14(3), 202; https://doi.org/10.3390/catal14030202 - 19 Mar 2024
Cited by 2 | Viewed by 1048
Abstract
The present study deals with the development, characterization, and performance of a Ni-based catalyst over a ceria-doped alumina support as a post-gasification step, in the conversion of biomass-derived tars. The catalysts were prepared using the incipient wetness technique and characterized chemically and physically [...] Read more.
The present study deals with the development, characterization, and performance of a Ni-based catalyst over a ceria-doped alumina support as a post-gasification step, in the conversion of biomass-derived tars. The catalysts were prepared using the incipient wetness technique and characterized chemically and physically using NH3-TPD, CO2-TPD, H2-TPR, XRD, Pyridine-FTIR, N2 physisorption, and H2-Pulse Chemisorption. It was observed that the 5 wt% CeO2 reduced the strong and very strong acid sites of the alumina support and helped with the dispersion of nickel. It was noticed that the nickel crystallite sizes and metal dispersion remained unchanged as the nickel loading increased. The performance of the catalysts was studied in a mini-fluidized CREC Riser Simulator at different temperatures and reaction times. The selected tar surrogate was 2-methoxy-4-methylphenol, given its functional group similarities with lignin-derived tars. A H2/CO2 gas blend was used to emulate the syngas at post-gasification conditions. The obtained tar surrogate conversion was higher than 75%, regardless of the reaction conditions. Furthermore, the catalysts used in this research provided an enhancement in the syngas product composition when compared to that observed in the thermal experiments. The presence of hydrocarbons greater than CH4 (C1+) was reduced at 525 °C, from 96 ± 3% with no catalyst, to 85 ± 2% with catalyst and steam, to 68 ± 4% with catalyst and steam-H2/CO2. Thus, the catalyst that we developed promoted tar cracking, tar reforming, and water-gas shift reactions, with a H2/CO ratio higher than 3.8, providing a syngas suitable for alcohol synthesis. Full article
(This article belongs to the Special Issue Fluidizable Catalysts for Novel Chemical Processes)
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Graphical abstract

29 pages, 9357 KiB  
Article
A Fluidizable Catalyst for N-Butane Oxidative Dehydrogenation under Oxygen-Free Reaction Conditions
by Abdulhamid Bin Sulayman, Nicolas Torres Brauer and Hugo de Lasa
Catalysts 2023, 13(12), 1462; https://doi.org/10.3390/catal13121462 - 23 Nov 2023
Cited by 2 | Viewed by 1303
Abstract
This study evaluates the effectiveness of fluidizable VOx/MgO-γAl2O3 catalysts for C4-olefin production via n-butane oxidative dehydrogenation (BODH). Catalysts were prepared via vacuum incipient wetness impregnation and then characterized by employing several techniques such as BET [...] Read more.
This study evaluates the effectiveness of fluidizable VOx/MgO-γAl2O3 catalysts for C4-olefin production via n-butane oxidative dehydrogenation (BODH). Catalysts were prepared via vacuum incipient wetness impregnation and then characterized by employing several techniques such as BET (Brunauer–Emmett–Teller) method, XRD (X-ray diffraction), LRS (laser Raman spectroscopy), XPS (X-ray photoelectron spectroscopy), TPR/TPO (temperature-programmed reduction/temperature-programmed oxidation), NH3-TPD (temperature-programmed desorption), NH3 -desorption kinetics and pyridine-FTIR. The BET analysis showed the prepared catalysts’ mesoporous structure and high surface areas. The XRD, LRS and XPS established the desirable presence of amorphous VOx phases. The TPR/TPO analyses corroborated catalyst stability over repeated reduction and oxidation cycles. The NH3-TPD and NH3 desorption kinetics showed that the catalysts had dominant moderate acidities and weak metal-support interactions. In addition, Pyridine-FTIR showed the critical influence of Lewis acidity. The VOx/MgO-γAl2O3 catalysts were evaluated for BODH using a fluidized CREC Riser Simulator, operated under gas-phase oxygen-free conditions, at 5 to 20 s reaction times, and at 450 °C to 600 °C temperatures. The developed VOx/MgO-γAl2O3 catalysts demonstrated performance stability throughout multiple injections of butane feed. Catalyst regeneration was also conducted after six consecutive BODH runs, and the coke formed was measured using TOC (Total Organic Carbon). Regarding the various BODH catalyst prepared, the 5 wt% V-doped MgO-γAl2O3 yielded in a fluidized CREC Riser Simulator the highest selectivity for C4-olefins, ranging from 82% to 86%, alongside a butane conversion rate of 24% to 27%, at 500 °C and at a 10 s reaction time. Full article
(This article belongs to the Special Issue Fluidizable Catalysts for Novel Chemical Processes)
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