Green Chemistry and Environmental Processes

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

Deadline for manuscript submissions: closed (31 October 2020) | Viewed by 15172

Special Issue Editors

Department of Inorganic Chemistry, University of Granada, Granada, Spain
Interests: carbon nanomaterials; carbon–metal nanocomposites; physical and chemical characterization; synergistic effects; adsorption; environmental catalysis; air/water abatement; value-added products
Special Issues, Collections and Topics in MDPI journals
Department of Inorganic Chemistry, University of Granada, Granada, Spain
Interests: carbon nanostructures; graphene; nanostructured metal oxide; structured catalysts and membranes; chemical functionalization; advanced oxidation processes; air/water treatment; desalination
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Over the last few decades, the occurrence of contaminants of emerging concern in natural effluents, i.e., water and air, is maintaining high levels. The exponentially growing population, global warming, economic expansion, and intensive agricultural practices will undoubtedly aggravate this scenario for years to come. Thus, together with the reduction of actual pollution levels, the development of new and environmentally friendly production methods is needed. Green chemistry is based on the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and application of chemical products. Alternatively, clean production can be also achieved by efficient treatment of effluents. The design and the optimization of novel synthesis/treatment processes, especially catalyzed processes, using different approaches, such as photo-, electro-, sono- or classical thermal-activated processes are highly in demand, because active and selective catalysts diminish the consumption of energy and chemicals and avoid separation procedures, thus improving the economy and safety of the planet. Advanced oxidation technologies (AOTs) have been demonstrated to be efficient in the removal of this type of contaminants from water. They are based on the generation of highly oxidizing radicals, which destroy the pollutant molecules. Among them, heterogeneous photocatalysis, Fenton processes, catalytic ozonation, and catalytic wet air oxidation have gained importance in the last few years. Air treatment can be also achieved by different catalytic processes, depending on the contaminant to be removed. For instance, catalytic combustion of volatile organic compounds (VOCs) and particulate materials (soot), catalytic reduction of NOx, SOx, and COx, and dehalogenation, among others, have been used for the treatment of polluted air streams.  

This Special Issue will be devoted to the development of novel catalysts by conventional or advanced procedures, their characterization though a broad spectrum of techniques, and their application in green synthesis procedures or treatment of air and water effluents. The optimization and the analysis of the operating parameters of these processes are also of high interest. 

It is our pleasure to invite you to submit a manuscript to this Special Issue. Full papers, short communications, and reviews are welcome.   

Prof. Francisco José Maldonado-Hódar
Dr. Sónia A.C. Carabineiro
Dr. Sergio Morales Torres
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

  • Design and development of catalysts and processes
  • Physical and chemical characterization
  • Green synthesis processes
  • Water treatment
  • Air treatment
  • Advanced oxidation processes
  • Selective reduction processes
  • Photo-, sono-, electro- and thermal catalysis

Published Papers (5 papers)

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Editorial

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2 pages, 183 KiB  
Editorial
Green Chemistry and Environmental Processes
Catalysts 2021, 11(5), 643; https://doi.org/10.3390/catal11050643 - 19 May 2021
Viewed by 1604
Abstract
This Special Issue was designed based on two complementary principles, both aimed at developing environmentally friendly production processes, in which catalysis plays a leading role [...] Full article
(This article belongs to the Special Issue Green Chemistry and Environmental Processes)

Research

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16 pages, 4893 KiB  
Article
Glucose–Carbon Hybrids as Pt Catalyst Supports for the Continuous Furfural Hydroconversion in Gas Phase
Catalysts 2021, 11(1), 49; https://doi.org/10.3390/catal11010049 - 01 Jan 2021
Cited by 9 | Viewed by 2424
Abstract
Glucose–carbon hybrids were synthetized with different carbon materials, namely carbon nanotubes, reduced graphene oxide, carbon black and activated carbon by a hydrothermal treatment. These carbon hybrids were used as Pt-supports (1 wt.%) for the furfural (FUR) hydroconversion in the gas phase at mild [...] Read more.
Glucose–carbon hybrids were synthetized with different carbon materials, namely carbon nanotubes, reduced graphene oxide, carbon black and activated carbon by a hydrothermal treatment. These carbon hybrids were used as Pt-supports (1 wt.%) for the furfural (FUR) hydroconversion in the gas phase at mild operating conditions (i.e., P = 1 atm and T = 200 °C). The physicochemical properties (porosity, surface chemistry, Pt-dispersion, etc.) were analyzed by different techniques. Glucose–carbon hybrids presented apparent surface areas between 470–500 m2 g−1, a neutral character and a good distribution of small Pt-nanoparticles, some large ones with octahedral geometry being also formed. Catalytic results showed two main reaction pathways: (i) FUR hydrogenation to furfuryl alcohol (FOL), and (ii) decarbonylation to furane (FU). The products distribution depended on the reaction temperature, FOL or FU being mainly produced at low (120–140 °C) or high temperatures (170–200 °C), respectively. At intermediate temperatures, tetrahydrofurfuryl alcohol was formed by secondary FOL hydrogenation. FUR hydroconversion is a structure-sensitive reaction, rounded-shape Pt-nanoparticles producing FU, while large octahedral Pt-particles favor the formation of FOL. Pt-catalysts supported on glucose–carbon hybrids presented a better catalytic performance at low temperature than the catalyst prepared on reference material, no catalyst deactivation being identified after several hours on stream. Full article
(This article belongs to the Special Issue Green Chemistry and Environmental Processes)
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12 pages, 1310 KiB  
Article
Pyrolysis of Polyethylene Terephthalate over Carbon-Supported Pd Catalyst
Catalysts 2020, 10(5), 496; https://doi.org/10.3390/catal10050496 - 01 May 2020
Cited by 32 | Viewed by 4636
Abstract
Pyrolysis of polyethylene terephthalate (PET) produces polycyclic hydrocarbons and biphenyl derivatives that are harmful to human health and the environment. Therefore, a palladium metal catalyst (5 wt.% Pd loaded on activated carbon) was used to prevent the formation of harmful materials. When a [...] Read more.
Pyrolysis of polyethylene terephthalate (PET) produces polycyclic hydrocarbons and biphenyl derivatives that are harmful to human health and the environment. Therefore, a palladium metal catalyst (5 wt.% Pd loaded on activated carbon) was used to prevent the formation of harmful materials. When a Pd catalyst/PET ratio of 0.01 was applied in pyrolysis of PET, it did not show a meaningful difference in the generation of polycyclic hydrocarbons and biphenyl derivatives. However, when a Pd catalyst/PET ratio of 0.05 was used during pyrolysis, it prevented their formation and generation at experimental temperature ranges (400–700 °C). For example, the concentration of 2-naphthalenecarboxylic acid produced, which is a typical polycyclic hydrocarbon material, was reduced by 44%. In addition, the concentration of biphenyl-4-carboxylic acid, which is contained in biphenyl derivatives, was reduced by 79% compared to non-catalytic pyrolysis at 800 °C. This was because the ring-opening reaction and free radical mechanism caused by the Pd catalyst and thermal cracking were dominant during the pyrolysis of PET. Apart from these materials, amine compounds were generated as products of the pyrolysis of PET. Amine concentration showed a similar trend with polycyclic hydrocarbons and benzene derivatives. Based on these results, the total concentration of polycyclic hydrocarbons and biphenyl derivatives was compared; the results confirmed that the concentrations of all substances were reduced. This research suggests that a metal-supported catalyst will help create a more environmentally friendly and reliable method of industrial plastic waste disposal. Full article
(This article belongs to the Special Issue Green Chemistry and Environmental Processes)
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13 pages, 2360 KiB  
Article
Active, Selective, and Recyclable Zr(SO4)2/SiO2 and Zr(SO4)2/Activated Carbon Solid Acid Catalysts for Esterification of Malic Acid to Dimethyl Malate
Catalysts 2020, 10(4), 384; https://doi.org/10.3390/catal10040384 - 01 Apr 2020
Cited by 4 | Viewed by 2344
Abstract
The esterification of malic acid using traditional homogenous catalysts suffers from the difficulty in reuse of the catalyst and undesirable side reactions. In this work, Zr(SO4)2/SiO2 and Zr(SO4)2/activated carbon (AC) as solid acid catalysts [...] Read more.
The esterification of malic acid using traditional homogenous catalysts suffers from the difficulty in reuse of the catalyst and undesirable side reactions. In this work, Zr(SO4)2/SiO2 and Zr(SO4)2/activated carbon (AC) as solid acid catalysts were prepared for malic acid esterification with methanol. The conversion of malic acid over these two catalysts is comparable to that over H2SO4 and unsupported Zr(SO4)2∙4H2O catalysts; however; a 99% selectivity of dimethyl malate can be realized on these two supported catalysts, which is much higher than that of conventional H2SO4 (75%) and unsupported Zr(SO4)2∙4H2O (80%) catalysts, highlighting the critical role of AC and SiO2 supports in tuning the selectivity. We suggest that the surface hydroxyls of AC or lattice O2− ions from SiO2 donate electrons to Zr4+ in Zr(SO4)2/AC and Zr(SO4)2/SiO2 catalysts, which results in the increase in electron density on Zr4+. The enhanced electron density on Zr4+ reduces the degree of H delocalization from crystal water and then decreases the Brønsted acid strength. Consequently, the reduced Brønsted acid strength of Zr(SO4)2/AC and Zr(SO4)2/SiO2 catalysts suppresses the intermolecular dehydration side reaction. In addition, these two supported catalysts can be easily separated from the reaction system by simple filtration with almost no loss of activity. Full article
(This article belongs to the Special Issue Green Chemistry and Environmental Processes)
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17 pages, 5565 KiB  
Article
Comparision on the Low-Temperature NH3-SCR Performance of γ-Fe2O3 Catalysts Prepared by Two Different Methods
Catalysts 2019, 9(12), 1018; https://doi.org/10.3390/catal9121018 - 03 Dec 2019
Cited by 14 | Viewed by 3464
Abstract
Maghemite (γ-Fe2O3) catalysts were prepared by two different methods, and their activities and selectivities for selective catalytic reduction of NO with NH3 were investigated. The methods of X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), hydrogen [...] Read more.
Maghemite (γ-Fe2O3) catalysts were prepared by two different methods, and their activities and selectivities for selective catalytic reduction of NO with NH3 were investigated. The methods of X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), ammonia temperature-programmed desorption (NH3-TPD), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) were used to characterize the catalysts. The resulted demonstrated that the γ-Fe2O3 nanoparticles prepared by the facile method (γ-Fe2O3–FM) not only exhibited better NH3-SCR activity and selectivity than the catalyst prepared by the coprecipitation method but also showed improved SO2 tolerance. This superior NH3-SCR performance was credited to the existence of the larger surface area, better pore structure, a high concentration of lattice oxygen and surface-adsorbed oxygen, good reducibility, a lot of acid sites, lower activation energy, adsorption of the reactants, and the existence of unstable nitrates on the surface of the γ-Fe2O3–FM. Full article
(This article belongs to the Special Issue Green Chemistry and Environmental Processes)
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