Special Issue "Heterogeneous Catalysis for Environmental Remediation"

A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: closed (28 February 2017)

Special Issue Editors

Guest Editor
Prof. Dr. Shaobin Wang

Department of Chemical Engineering, Curtin University, GPO Box U1987, WA, 6845, Australia
Website | E-Mail
Interests: catalysis; adsorption; photocatalysis; nanomaterials; chemical engineering
Guest Editor
Dr. Xiaoguang Duan

Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth WA 6845, Australia
E-Mail
Interests: advanced oxidative processes; nanotechnology; environmental chemistry; heterogeneous catalysis; nanocarbon materials

Special Issue Information

Dear Colleagues,

Catalytic processes have significantly boosted the chemical industry and the development of human society. The pursuit of a sustainable future requires green catalytic processes in chemical production, energy conversion, and environmental remediation. For environmental catalysis, developing robust, efficient, and environmentally-benign catalysts and processes are always highly desired for the complete removal of toxic and hazardous substances in polluted air, soil, and wastewater. Moreover, considerable efforts are still required to conduct insightful mechanistic studies on the relationships between material morphology, surface chemistry, and catalytic performances, which would, not only provide meaningful guidance for rational material design, but also enable potential applications in environmental science. Advanced oxidative processes have been demonstrated as one of the most effective technologies for environmental remediation, which usually involves photocatalysis and activation of superoxides (e.g., ozone, hydrogen peroxide, peroxymonosulfate, and persulfate) to generate reactive species for the transition/decomposition of pollutants in a contaminated system. This Special Issue aims to cover recent progress and advances in designing, synthesizing, characterizing, and evaluating advanced metals, metal oxides, nanocarbons, and novel hybrids for photocatalysis, advanced oxidative processes, and other applications in catalytic oxidation and environmental remediation.

Prof. Shaobin Wang
Dr. Xiaoguang Duan
Guest Editors

Manuscript Submission Information

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Keywords

  • advanced oxidative processes
  • heterogeneous catalysis
  • nanocarbons
  • metal oxides
  • persulfate activation
  • hydrogen peroxide
  • photocatalysis
  • wastewater treatment
  • peroxymonosulfate

Published Papers (24 papers)

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Editorial

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Open AccessEditorial Heterogeneous Catalysis for Environmental Remediation
Catalysts 2017, 7(8), 236; doi:10.3390/catal7080236
Received: 11 August 2017 / Revised: 11 August 2017 / Accepted: 15 August 2017 / Published: 16 August 2017
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Abstract
The intensive human activities in chemical industry and environmental purification urge the development of advanced protocols for green production and waste management. [...]
Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)

Research

Jump to: Editorial, Review

Open AccessArticle Catalytic Decomposition of N2O over Cu–Zn/ZnAl2O4 Catalysts
Catalysts 2017, 7(5), 166; doi:10.3390/catal7050166
Received: 18 April 2017 / Revised: 12 May 2017 / Accepted: 17 May 2017 / Published: 22 May 2017
Cited by 1 | PDF Full-text (6730 KB) | HTML Full-text | XML Full-text
Abstract
The catalytic decomposition of N2O was investigated over Cu-Zn/ZnAl2O4 catalysts in the temperature range of 400–650 °C Catalytic samples have been prepared by wet impregnation method. Prepared catalysts were characterized using several techniques like BET surface area, X-ray
[...] Read more.
The catalytic decomposition of N2O was investigated over Cu-Zn/ZnAl2O4 catalysts in the temperature range of 400–650 °C Catalytic samples have been prepared by wet impregnation method. Prepared catalysts were characterized using several techniques like BET surface area, X-ray diffraction (XRD), and Scanning electron microscopy (SEM). The Cu-Zn/ZnAl2O4 showed higher catalytic performance along with long term stability during N2O decomposition. The Cu-Zn/ZnAl2O4 catalysts yielded 100% N2O conversion at 650 °C. The Cu-Zn/ZnAl2O4 catalysts are promising for decrease this strong greenhouse gas in the chemical industry. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Solar and Visible Light Illumination on Immobilized Nano Zinc Oxide for the Degradation and Mineralization of Orange G in Wastewater
Catalysts 2017, 7(5), 164; doi:10.3390/catal7050164
Received: 4 March 2017 / Revised: 2 May 2017 / Accepted: 10 May 2017 / Published: 20 May 2017
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Abstract
An advanced oxidation process (AOP) utilizing immobilized zinc oxide (ZnO) photocatalyst was employed to decolorize and mineralize orange G (OG) azo dye in wastewater under solar and visible light irradiation. This AOP employed visible light and ZnO in a so-called Vis/ZnO process. Operating
[...] Read more.
An advanced oxidation process (AOP) utilizing immobilized zinc oxide (ZnO) photocatalyst was employed to decolorize and mineralize orange G (OG) azo dye in wastewater under solar and visible light irradiation. This AOP employed visible light and ZnO in a so-called Vis/ZnO process. Operating parameters, including ZnO dosage, initial OG concentration, pH, visible-light intensity, catalyst loaded area, and treatment volume were investigated to illustrate their influences on OG degradation and mineralization. From the results, neither visible light alone, nor the ZnO adsorption process could degrade or remove OG from wastewater. However, for the Vis/ZnO process, the higher ZnO dosage and visible light intensity are two major parameters to improve the OG degradation and total organic carbons (TOC) mineralization. The initial pH of 11 was the most effective pH condition on the OG degradation. The first-order rate constant is exponentially decreased from 0.025 to 0.0042 min−1 with the increase of the initial OG concentration and an empirical equation can be derived to estimate the first-order rate constant with a known initial OG concentration. In contrast, the first-order rate constant is linearly increased from 0.0027 to 0.0083 min−1 by increasing the visible light intensity. The results present that the Vis/ZnO process is an effective AOP for the degradation of OG in wastewater. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Influence of Dissolved Ions on the Water Purification Performance of TiO2-Impregnated Porous Silica Tubes
Catalysts 2017, 7(5), 158; doi:10.3390/catal7050158
Received: 27 April 2017 / Revised: 10 May 2017 / Accepted: 10 May 2017 / Published: 16 May 2017
Cited by 1 | PDF Full-text (3905 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
TiO2-coated porous silica glass tubes containing macropores were fabricated and evaluated for their water-purification capacity using aqueous solutions of methylene blue. From the results of photocatalytic degradation tests at different initial methylene blue concentrations, the equilibrium adsorption constant (K)
[...] Read more.
TiO2-coated porous silica glass tubes containing macropores were fabricated and evaluated for their water-purification capacity using aqueous solutions of methylene blue. From the results of photocatalytic degradation tests at different initial methylene blue concentrations, the equilibrium adsorption constant (K) was determined to be 4.6 × 10−2 L µmol−1, and the Langmuir-Hinshelwood rate constant (kLH) was calculated as 2.6 µM min−1. To determine the influence of ions on the efficiency of methylene blue degradation, we examined both Milli-Q water (soft water) and Contrex water (hard water) as solvents, and confirmed the reduced purification for the Contrex solution. It was, therefore, considered that the presence of inorganic salts decreased the photocatalytic efficiency. Furthermore, variations in the methylene blue decomposition ability were observed between anion-free and cation-free Contrex. Finally, we concluded that the efficiency of photocatalytic decomposition of TiO2 was influenced by multiple parameters, including the presence of anions and cations, as well as the solution pH. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Effective Electron Transfer Pathway of the Ternary TiO2/RGO/Ag Nanocomposite with Enhanced Photocatalytic Activity under Visible Light
Catalysts 2017, 7(5), 156; doi:10.3390/catal7050156
Received: 24 March 2017 / Revised: 4 May 2017 / Accepted: 10 May 2017 / Published: 15 May 2017
Cited by 3 | PDF Full-text (6182 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Mesoporous TiO2/reduced graphene oxide/Ag (TiO2/RGO/Ag) ternary nanocomposite with an effective electron transfer pathway is obtained by an electrostatic self-assembly method and photo-assisted treatment. Compared with bare mesoporous TiO2 (MT) and mesoporous TiO2/RGO (MTG), the ternary mesoporous
[...] Read more.
Mesoporous TiO2/reduced graphene oxide/Ag (TiO2/RGO/Ag) ternary nanocomposite with an effective electron transfer pathway is obtained by an electrostatic self-assembly method and photo-assisted treatment. Compared with bare mesoporous TiO2 (MT) and mesoporous TiO2/RGO (MTG), the ternary mesoporous TiO2/RGO/Ag (MTGA) nanocomposite exhibited superior photocatalytic performance for the degradation of methylene blue (MB) under visible light, and the degradation rate reached 0.017 min−1, which was 3.4-times higher than that of MTG. What is more, the degradation rate of MTGA nanocomposite after three cycle times is 91.2%, and the composition is unchanged. In addition, we found that the OH•, h+ and especially O2•− contribute to the high photocatalytic activity of MTGA for MB degradation. It is proposed that Ag nanoparticles can form the local surface plasmon resonance (LSPR) to absorb the visible light and distract the electrons into MT, and RGO can accept the electrons from MT to accelerate the separation efficiency of photogenerated carriers. The establishment of MTGA ternary nanocomposite makes the three components act synergistically to enhance the photocatalytic performance. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Preparation of Salen–Metal Complexes (Metal = Co or Ni) Intercalated ZnCr-LDHs and Their Photocatalytic Degradation of Rhodamine B
Catalysts 2017, 7(5), 143; doi:10.3390/catal7050143
Received: 14 April 2017 / Revised: 28 April 2017 / Accepted: 4 May 2017 / Published: 7 May 2017
Cited by 1 | PDF Full-text (8314 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Salen–metal complexes (SalenM) were successfully intercalated into ZnCr layered double hydroxides (LDHs) through coprecipitation method, then a series of novel organic–inorganic hybrid materials were obtained. The structure and properties of the materials were thoroughly characterized by inductively-coupled plasma atomic emission spectrometry (ICP-AES), powder
[...] Read more.
Salen–metal complexes (SalenM) were successfully intercalated into ZnCr layered double hydroxides (LDHs) through coprecipitation method, then a series of novel organic–inorganic hybrid materials were obtained. The structure and properties of the materials were thoroughly characterized by inductively-coupled plasma atomic emission spectrometry (ICP-AES), powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), and ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS). Meanwhile, with Rhodamine B (RhB) as a target contaminant, the photocatalytic activities of SalenM-intercalated ZnCr-LDHs were investigated and compared with the traditional LDHs (ZnCr-LDHs, ZnCoCr-LDHs, and ZnNiCr-LDHs). Furthermore, the effect of the intercalation amount of SalenM (M = Co or Ni) on the photocatalytic activity was studied. The results showed that when the molar ratio of SalenM to Cr was 0.75, SalenM-intercalated ZnCr-LDHs exhibited significantly higher photocatalytic activities than the traditional LDHs. The degradation rates of RhB reached about 90%, and all of them had good recycling rates. In addition, the kinetics of photocatalytic process and the mechanism of photocatalysis are discussed. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Cobalt-iron Oxide, Alloy and Nitride: Synthesis, Characterization and Application in Catalytic Peroxymonosulfate Activation for Orange II Degradation
Catalysts 2017, 7(5), 138; doi:10.3390/catal7050138
Received: 27 February 2017 / Revised: 4 April 2017 / Accepted: 24 April 2017 / Published: 4 May 2017
Cited by 1 | PDF Full-text (6632 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In meeting the need for environmental remediation in wastewater treatment and the development of popular sulfate-radical-based advanced oxidation processes (SR-AOPs), a series of Co/Fe-based catalysts with confirmed phase structure were prepared through extended soft chemical solution processes followed by atmosphere-dependent calcination. Powder X-ray
[...] Read more.
In meeting the need for environmental remediation in wastewater treatment and the development of popular sulfate-radical-based advanced oxidation processes (SR-AOPs), a series of Co/Fe-based catalysts with confirmed phase structure were prepared through extended soft chemical solution processes followed by atmosphere-dependent calcination. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and 57Fe Mössbauer spectroscopy were employed to characterize the composition, morphology, crystal structure and chemical state of the prepared catalysts. It was shown that calcination in air, nitrogen and ammonia atmospheres generated Co-Fe catalysts with cobalt ferrite (CoFe2O4), Co-Fe alloy and Co-Fe nitride as dominant phases, respectively. The prepared Co/Fe-based catalysts were demonstrated to be highly efficient in activating peroxymonosulfate (PMS) for organic Orange II degradation. The activation efficiency of the different catalysts was found to increase in the order CoFe2O4 < Co-Fe nitride < Co-Fe alloy. Sulfate radical was found to be the primary active intermediate species contributing to the dye degradation for all the participating catalysts. Furthermore, a possible reaction mechanism was proposed for each of the studied catalysts. This study achieves progress in efficient cobalt-iron catalysts using in the field of SR-AOPs, with potential applications in environment remediation. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Catalytic Abatement of Nitrous Oxide Coupled with Ethane Oxydehydrogenation over Mesoporous Cr/Al2O3 Catalyst
Catalysts 2017, 7(5), 137; doi:10.3390/catal7050137
Received: 21 March 2017 / Revised: 20 April 2017 / Accepted: 25 April 2017 / Published: 4 May 2017
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Abstract
Waste nitrous oxide (N2O) was utilized as an oxidant for ethane oxydehydrogenation reaction at the temperature range from 450 °C to 700 °C over the mesoporous Cr/Al2O3 catalyst synthesized via the one-pot evaporation-induced self-assembly (EISA) method. The catalyst
[...] Read more.
Waste nitrous oxide (N2O) was utilized as an oxidant for ethane oxydehydrogenation reaction at the temperature range from 450 °C to 700 °C over the mesoporous Cr/Al2O3 catalyst synthesized via the one-pot evaporation-induced self-assembly (EISA) method. The catalyst was characterized by X-ray diffraction, transmission electron microscopy, and nitrogen adsorption-desorption analysis. The obtained mesoporous material with favorable textural property and advantageous thermal stability was investigated as the catalyst for ethane oxydehydrogenation. It was found that the utilization of N2O as an oxidant for the oxydehydrogenation reaction of ethane resulted in simultaneous and complete N2O abatement. Moreover, the catalytic conversion of C2H6 to C2H4 was increased from 18% to 43% as the temperature increased from 450 °C to 700 °C. The increased N2O concentration from 5 vol % to 20 vol % resulted in an increased ethane conversion but decreased ethylene selectivity because the nonselective reactions occurred. Ethane was converted into ethylene with approximately 51% selectivity and 22% yield at 700 °C and N2O concentration of 10%. After a catalytic steady state was reached, no obvious decline was observed during a 15 h evaluation period. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle A Study of Low-Temperature CO Oxidation over Mesoporous CuO-TiO2 Nanotube Catalysts
Catalysts 2017, 7(5), 129; doi:10.3390/catal7050129
Received: 5 April 2017 / Revised: 20 April 2017 / Accepted: 21 April 2017 / Published: 28 April 2017
Cited by 2 | PDF Full-text (8222 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Supported copper oxide nanoparticles have attracted considerable attention as active and non-precious catalysts for many catalytic oxidation reactions. Herein, mesoporous xCuO-TiO2 nanotube catalysts were fabricated, and their activity and kinetics toward CO oxidation were studied. The morphology and structure of the prepared
[...] Read more.
Supported copper oxide nanoparticles have attracted considerable attention as active and non-precious catalysts for many catalytic oxidation reactions. Herein, mesoporous xCuO-TiO2 nanotube catalysts were fabricated, and their activity and kinetics toward CO oxidation were studied. The morphology and structure of the prepared catalysts were systematically studied using SEM, TEM, EDS, EDX, XRD, TGA, BET, XPS, H2-TPR, and Raman techniques. The BET surface area study revealed the effect of the large surface area of the mesoporous TiO2 nanotubes on promoting the catalytic activity of prepared catalysts. The results also revealed the existence of strong metal-support interactions in the CuO-TiO2 nanotube catalyst, as indicated by the up-shift of the E2g vibrational mode of TiO2 from 144 cm−1 to 145 cm−1 and the down-shift of the binding energy (BE) of Ti 2p3/2 from 458.3 eV to 458.1 eV. The active phase of the catalyst consists of fine CuO nanoparticles dispersed on a mesoporous anatase TiO2 nanotube support. The 50-CuO-TiO2 nanotube catalyst demonstrated the highest catalytic activity with 100% CO conversion at T100 = 155 °C and a reaction rate of 36 µmole s−1 g−1. Furthermore, the catalyst demonstrated excellent long-term stability with complete CO conversion that was stable for 60 h under a continuous stream. The enhanced catalytic activity is attributed to the interplay at the interface between the active CuO phase and the TiO2 nanotubes support. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Ion-Exchange of Cu2+ Promoted Layered Perovskite K2La2Ti3O10 for Photocatalytic Degradation Chlorobenzene under Simulated Solar Light Irradiation
Catalysts 2017, 7(5), 126; doi:10.3390/catal7050126
Received: 26 February 2017 / Revised: 19 April 2017 / Accepted: 21 April 2017 / Published: 26 April 2017
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Abstract
The layered perovskite, K2La2Ti3O10 was prepared by sol-gel method. Ion-exchange of Cu2+ was prepared to improve the photocatalytic activity of K2La2Ti3O10 for chlorobenzene degradation under simulated solar light
[...] Read more.
The layered perovskite, K2La2Ti3O10 was prepared by sol-gel method. Ion-exchange of Cu2+ was prepared to improve the photocatalytic activity of K2La2Ti3O10 for chlorobenzene degradation under simulated solar light irradiation. The original K2La2Ti3O10 and Cu2+/K2La2Ti3O10 were characterized by power X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and specific surface area measurement. The XRD analysis shows that Cu2+ ions is incorporated in place of K+ ions and the grain growth is inhibited by ion-exchange. With the rise of calcination temperature, more interlayer Cu2+ was converted into new crystal phase CuO. The degradation ratio reaches 51.1% on Cu2+/K2La2Ti3O10 calcined at 500 °C in air, which is higher 16.9% than the original K2La2Ti3O10. It should be ascribed to the narrow interlayer distance, the formation of CuO, smaller grain size, and the high visible light absorption on the surface of Cu2+/K2La2Ti3O10 calcined at 500 °C. It is found that the exposure of CO2 could promote the photocatalytic activity of Cu2+/K2La2Ti3O10. It also suggests that CO2 is involved in the reduction to form benzaldehyde during decomposition of chlorobenzene. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle SO42−/Sn-MMT Solid Acid Catalyst for Xylose and Xylan Conversion into Furfural in the Biphasic System
Catalysts 2017, 7(4), 118; doi:10.3390/catal7040118
Received: 22 February 2017 / Revised: 1 April 2017 / Accepted: 11 April 2017 / Published: 17 April 2017
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Abstract
A sulphated tin ion-exchanged montmorillonite (SO42−/Sn-MMT) was successfully prepared by the ion exchange method of montmorillonite (MMT) with SnCl4, followed by the sulphation. This catalysis was applied as a solid acid catalyst for the heterogeneous catalytic transformations of
[...] Read more.
A sulphated tin ion-exchanged montmorillonite (SO42−/Sn-MMT) was successfully prepared by the ion exchange method of montmorillonite (MMT) with SnCl4, followed by the sulphation. This catalysis was applied as a solid acid catalyst for the heterogeneous catalytic transformations of xylose and xylan into furfural in the bio-based 2-methyltetrahydrofuran/H2O biphasic system. These prepared catalysts were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), temperature programmed desorption of ammonia (NH3-TPD), pyridine adsorbed Fourier transform infrared spectroscopy (Py-FTIR), element analysis (EA) and Brunauer-Emmett-Teller (BET) method. Their catalytic performance for xylose and xylan into furfural was also investigated. The reaction parameters such as the initial xylose and xylan concentration, the amounts of catalyst, the organic-to-aqueous phase volume ratio, the reaction temperature and time were studied to optimize the reaction conditions. Results displayed that SO42−/Sn-MMT contained both Brønsted acid and Lewis acid sites, and SO42− ions were contributive to the formation of stronger Brønsted acid sites, which could improve the reaction efficiency. Reaction parameters had significant influence on the furfural production. The substitution of water by the saturated NaCl solution in the aqueous phase also had an important effect on the xylose and xylan conversion. The highest furfural yields were achieved up to 79.64% from xylose and 77.35% from xylan under the optimized reaction conditions (160 °C, 120 min; 160 °C, 90 min). Moreover, the prepared catalyst was stable and was reused five times with a slight decrease (10.0%) of the furfural yield. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Study of the V2O5-WO3/TiO2 Catalyst Synthesized from Waste Catalyst on Selective Catalytic Reduction of NOx by NH3
Catalysts 2017, 7(4), 110; doi:10.3390/catal7040110
Received: 1 December 2016 / Revised: 16 March 2017 / Accepted: 6 April 2017 / Published: 8 April 2017
Cited by 3 | PDF Full-text (1867 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
V2O5-WO3/TiO2 catalysts were synthesized from waste selective catalytic reduction (SCR) catalyst through oxalic acid leaching and impregnating with various V2O5 mass loadings. The denitration (deNOx) activity and physiochemical properties of the
[...] Read more.
V2O5-WO3/TiO2 catalysts were synthesized from waste selective catalytic reduction (SCR) catalyst through oxalic acid leaching and impregnating with various V2O5 mass loadings. The denitration (deNOx) activity and physiochemical properties of the catalysts were investigated. All the catalysts were characterized by N2 adsorption/desorption, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and H2-temperature programmed reduction. The evaluation result revealed that the deNOx activity of newly synthesized catalyst with 1.0% V2O5 was almost recovered to the level of fresh catalyst, with NO conversion being recovered to 91% at 300 °C, and it also showed a good resistance to SO2 and H2O. The characterization results showed that the decrease of impurities, partial recovery of the V4+/V5+ ratio, and increased reducibility were mainly responsible for the recovery of catalytic activity. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Thermal Activation of CuBTC MOF for CO Oxidation: The Effect of Activation Atmosphere
Catalysts 2017, 7(4), 106; doi:10.3390/catal7040106
Received: 24 February 2017 / Revised: 26 March 2017 / Accepted: 4 April 2017 / Published: 7 April 2017
Cited by 3 | PDF Full-text (4393 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
High performance catalysts for carbon monoxide (CO) oxidation were obtained through thermal activation of a CuBTC (BTC: 1,3,5-benzenetricarboxylic acid) metal–organic framework (MOF) in various atmospheres. X-ray diffraction (XRD), X-ray photonelectron spectroscopy (XPS), N2 adsorption–desorption measurement, and field emission scanning electron microscopy (FESEM)
[...] Read more.
High performance catalysts for carbon monoxide (CO) oxidation were obtained through thermal activation of a CuBTC (BTC: 1,3,5-benzenetricarboxylic acid) metal–organic framework (MOF) in various atmospheres. X-ray diffraction (XRD), X-ray photonelectron spectroscopy (XPS), N2 adsorption–desorption measurement, and field emission scanning electron microscopy (FESEM) were adopted to characterize the catalysts. The results show that thermal activation by reductive H2 may greatly destroy the structure of CuBTC. Inert Ar gas has a weak influence on the structure of CuBTC. Therefore, these two catalysts exhibit low CO oxidation activity. Activating with O2 is effective for CuBTC catalysts, since active CuO species may be obtained due to the slight collapse of CuBTC structure. The highest activity is obtained when activating with CO reaction gas, since many pores and more effective Cu2O is formed during the thermal activation process. These results show that the structure and chemical state of coordinated metallic ions in MOFs are adjustable by controlling the activation conditions. This work provides an effective method for designing and fabricating high performance catalysts for CO oxidation based on MOFs. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Three-Dimensional TiO2 Structures Incorporated with Tungsten Oxide for Treatment of Toxic Aromatic Volatile Compounds
Catalysts 2017, 7(4), 97; doi:10.3390/catal7040097
Received: 24 February 2017 / Revised: 16 March 2017 / Accepted: 20 March 2017 / Published: 23 March 2017
Cited by 1 | PDF Full-text (3670 KB) | HTML Full-text | XML Full-text
Abstract
This study assessed 3D WO3–TiO2 nanoflowers (WTNF) synthesized by a combined hydrothermal–ultrasonication–impregnation method for their applicability to the treatment of aromatic volatile compounds under visible-light illumination. The scanning electron microscopy exhibited the formation of 3D structures in the prepared WTNF
[...] Read more.
This study assessed 3D WO3–TiO2 nanoflowers (WTNF) synthesized by a combined hydrothermal–ultrasonication–impregnation method for their applicability to the treatment of aromatic volatile compounds under visible-light illumination. The scanning electron microscopy exhibited the formation of 3D structures in the prepared WTNF samples. The X-ray diffraction patterns and energy dispersive X-ray results indicated a successful incorporation of WO3 into TNF structures. The UV-visible spectroscopy showed that the prepared WTNF samples can be functioned under visible light irradiation. The output-to-input concentration ratios of toluene and o-xylene with WTNF samples were lower than those of TiO2 nanoflowers. These findings were illustrated on the basis of charge separation ability, adsorption capability, and light absorption of the sample photocatalysts. The input-to-output concentration ratios of the target chemicals were lowest for 10 M NaOH and highest for 5 M NaOH. The photocatalytic degradation efficiencies of WTNF sample photocatalysts increased with increasing WO3 content from 0.1% to 1.0%, and dropped gradually with increasing WO3 content further to 4.0%. Light-emitting-diodes (LEDs) are a more highly energy-efficient light source compared to a conventional lamp for the photocatalytic degradation of toluene and o-xylene, although the photocatalytic activity is higher for the conventional lamp. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Biotemplated Mesoporous TiO2/SiO2 Composite Derived from Aquatic Plant Leaves for Efficient Dye Degradation
Catalysts 2017, 7(3), 82; doi:10.3390/catal7030082
Received: 10 January 2017 / Accepted: 7 March 2017 / Published: 9 March 2017
Cited by 1 | PDF Full-text (4282 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The biotemplating technique is an environmental-protective high-efficiency new technology by which the resulting TiO2 may simultaneously attain the duplication of structure and self-doping elements from biotemplate materials, which is highly desirable for photocatalytic applications. In this paper, aquatic plant leaves—including reed, water hyacinth,
[...] Read more.
The biotemplating technique is an environmental-protective high-efficiency new technology by which the resulting TiO2 may simultaneously attain the duplication of structure and self-doping elements from biotemplate materials, which is highly desirable for photocatalytic applications. In this paper, aquatic plant leaves—including reed, water hyacinth, and duckweed—were used as both templates and silicon precursors to successfully synthesize biomorphic TiO2/SiO2 composite with mesoporous structures. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption, and UV–visible diffuse reflectance spectra were applied to characterize the microstructures of the samples. The results show that all TiO2/SiO2 composites are mainly composed of an anatase phase with mesoporous structure and possess high specific surface area. Compared with commercial Degussa P25 TiO2, all TiO2/SiO2 samples display intensive light-harvesting efficiency, particularly in the visible light range. The activities were evaluated by using gentian violet as a target for photocatalytic degradation experiments under simulated solar irradiation. The TiO2/SiO2 samples templated by reed and water hyacinth leaves exhibit high activity, while the TiO2/SiO2 samples obtained from duckweed are inferior to P25 in the degradation of gentian violet. A synergistic effect of SiO2 incorporation and structural construction through biotemplating is proposed to be beneficial to photocatalytic activity. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Comparison of Efficiencies and Mechanisms of Catalytic Ozonation of Recalcitrant Petroleum Refinery Wastewater by Ce, Mg, and Ce-Mg Oxides Loaded Al2O3
Catalysts 2017, 7(3), 72; doi:10.3390/catal7030072
Received: 21 December 2016 / Revised: 18 February 2017 / Accepted: 21 February 2017 / Published: 24 February 2017
Cited by 1 | PDF Full-text (3548 KB) | HTML Full-text | XML Full-text
Abstract
The use of catalytic ozonation processes (COPs) for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW) is rapidly expanding. In this study, magnesium (Mg), cerium (Ce), and Mg-Ce oxide-loaded alumina (Al2O3) were developed as cost efficient catalysts for
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The use of catalytic ozonation processes (COPs) for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW) is rapidly expanding. In this study, magnesium (Mg), cerium (Ce), and Mg-Ce oxide-loaded alumina (Al2O3) were developed as cost efficient catalysts for ozonation treatment of RPRW, having performance metrics that meet new discharge standards. Interactions between the metal oxides and the Al2O3 support influence the catalytic properties, as well as the efficiency and mechanism. Mg-Ce/Al2O3 (Mg-Ce/Al2O3-COP) reduced the chemical oxygen demand by 4.7%, 4.1%, 6.0%, and 17.5% relative to Mg/Al2O3-COP, Ce/Al2O3-COP, Al2O3-COP, and single ozonation, respectively. The loaded composite metal oxides significantly increased the hydroxyl radical-mediated oxidation. Surface hydroxyl groups (–OHs) are the dominant catalytic active sites on Al2O3. These active surface –OHs along with the deposited metal oxides (Mg2+ and/or Ce4+) increased the catalytic activity. The Mg-Ce/Al2O3 catalyst can be economically produced, has high efficiency, and is stable under acidic and alkaline conditions. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Novel Fe‐W‐Ce Mixed Oxide for the Selective Catalytic Reduction of NOx with NH3 at Low Temperatures
Catalysts 2017, 7(2), 71; doi:10.3390/catal7020071
Received: 16 January 2017 / Accepted: 16 February 2017 / Published: 20 February 2017
Cited by 2 | PDF Full-text (3556 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A set of novel iron doped cerium‐tungsten catalysts were prepared by sol‐gel method with a view to their application for low temperature selective catalytic reduction (SCR) of NOx with NH3 in power plants. With a molar ratio Fe/W/Ce of 0.5:1:1, a NOx reduction
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A set of novel iron doped cerium‐tungsten catalysts were prepared by sol‐gel method with a view to their application for low temperature selective catalytic reduction (SCR) of NOx with NH3 in power plants. With a molar ratio Fe/W/Ce of 0.5:1:1, a NOx reduction of >90% at 200 °C was achieved. In Fe-W-Ce catalysts with low iron oxide content, it was found that the iron compounds were highly dispersed and formed a solid solution within the cerium oxide lattice, which promoted the SCR activity. Large amounts of iron in the catalysts might form a layer of Fe2O3 on the catalyst surface, which induced the synergistic inhibition effect among Fe, Ce and W species. Moreover, the Fe‐W‐Ce catalysts possessed a high resistance to changed operation parameters as well as to deactivation by SO2 and/or H2O. The novel catalyst showed to be competitive among recently developed low‐temperature SCR catalysts. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Synergically Improving Light Harvesting and Charge Transportation of TiO2 Nanobelts by Deposition of MoS2 for Enhanced Photocatalytic Removal of Cr(VI)
Catalysts 2017, 7(1), 30; doi:10.3390/catal7010030
Received: 16 December 2016 / Revised: 3 January 2017 / Accepted: 3 January 2017 / Published: 19 January 2017
Cited by 4 | PDF Full-text (6192 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Herein, MoS2/TiO2 nanobelts heterojunction have been successfully synthesized by in situ growth method for photocatalytic reduction of Cr(VI). TiO2 nanobelts (NBs) with rough surface were prepared firstly by acidic treatment process, which is beneficial for deposition and growth of
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Herein, MoS2/TiO2 nanobelts heterojunction have been successfully synthesized by in situ growth method for photocatalytic reduction of Cr(VI). TiO2 nanobelts (NBs) with rough surface were prepared firstly by acidic treatment process, which is beneficial for deposition and growth of MoS2 to form heterojunctions. As a result of special energy level offset and nanostructure, MoS2/TiO2 NBs composite were endowed with higher light-harvesting capacity and charge transportation efficiency, which are indispensible merits for excellent photocatalytic activity. The photocatalytic reduction of Cr(VI) reveals that the synthesized MoS2/TiO2 NBs composite have superior photocatalytic ability than other samples. Meanwhile, a photoreduction mechanism is proposed based on the systematic investigation, where the photogenerated electrons are demonstrated as the dominant reductive species to reduce Cr(VI) to Cr(III). Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Synthesis of Magnetic Carbon Supported Manganese Catalysts for Phenol Oxidation by Activation of Peroxymonosulfate
Catalysts 2017, 7(1), 3; doi:10.3390/catal7010003
Received: 2 November 2016 / Revised: 10 December 2016 / Accepted: 21 December 2016 / Published: 26 December 2016
Cited by 1 | PDF Full-text (4710 KB) | HTML Full-text | XML Full-text
Abstract
Magnetic core/shell nanospheres (MCS) were synthesized by a novel and facile one-step hydrothermal method. Supported manganese oxide nanoparticles (Fe3O4/C/Mn) were obtained from various methods (including redox, hydrothermal and impregnation) using MCS as the support material and potassium permanganate as
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Magnetic core/shell nanospheres (MCS) were synthesized by a novel and facile one-step hydrothermal method. Supported manganese oxide nanoparticles (Fe3O4/C/Mn) were obtained from various methods (including redox, hydrothermal and impregnation) using MCS as the support material and potassium permanganate as the precursor of manganese oxide. The Mn/MCS catalysts were characterized by a variety of characterization techniques and the catalytic performances of Fe3O4/C/Mn nanoparticles were tested in activation of peroxymonosulfate to produce reactive radicals for phenol degradation in aqueous solutions. It was found that Fe3O4/C/Mn catalysts can be well dispersed and easily separated from the aqueous solutions by an external magnetic field. Kinetic analysis showed that phenol degradation on Fe3O4/C/Mn catalysts follows the first order kinetics. The peroxymonosulfate activation mechanism by Fe3O4/C/Mn catalysts for phenol degradation was then discussed. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle Microporous Zeolites as Catalysts for the Preparation of Decyl Glucoside from Glucose with 1-Decanol by Direct Glucosidation
Catalysts 2016, 6(12), 216; doi:10.3390/catal6120216
Received: 10 November 2016 / Revised: 15 December 2016 / Accepted: 15 December 2016 / Published: 21 December 2016
Cited by 1 | PDF Full-text (3068 KB) | HTML Full-text | XML Full-text
Abstract
The catalytic properties of microporous zeolite catalysts were evaluated in the synthesis of decyl glucoside from glucose with 1-decanol by direct glucosidation. The effects of the acidic properties and pore structure of the zeolite catalysts on the glucose conversions and decyl glucoside yields
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The catalytic properties of microporous zeolite catalysts were evaluated in the synthesis of decyl glucoside from glucose with 1-decanol by direct glucosidation. The effects of the acidic properties and pore structure of the zeolite catalysts on the glucose conversions and decyl glucoside yields were investigated. The conversions of glucose on the H+ ion-exchanged FAU, MFI, and BEA zeolite catalysts were above 70%. The conversion increased with decreasing acid strength of the catalysts. The highest conversion and yield of decyl glucoside were exhibited on the H-FAU(3) zeolite catalyst. The catalytic activities were enhanced with increasing amounts of acid sites. The selectivity of decyl glucopyranoside increased with decreasing Si/Al values for the same zeolite catalysts. The pore structure of H-FAU zeolite would allow sufficient spatial restriction to produce decyl glucopyranoside through the isomerization of decyl glucofuranoside into decyl glucopyranoside in its extensive pore channels. The selectivities of the decyl glucoside isomers relied significantly on the restricted transition state to the primary products due to their pore topologies. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle CuO Nanorods-Decorated Reduced Graphene Oxide Nanocatalysts for Catalytic Oxidation of CO
Catalysts 2016, 6(12), 214; doi:10.3390/catal6120214
Received: 18 November 2016 / Revised: 8 December 2016 / Accepted: 13 December 2016 / Published: 21 December 2016
Cited by 2 | PDF Full-text (7361 KB) | HTML Full-text | XML Full-text
Abstract
Developing an efficient non-noble catalyst for CO oxidation with high catalytic activity remains a challenge for practical applications. In this work, CuO nanorods decorated reduced graphene oxide (RGO) nanocatalysts were prepared via a facile one-step hydrothermal method. The structure and morphology of the
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Developing an efficient non-noble catalyst for CO oxidation with high catalytic activity remains a challenge for practical applications. In this work, CuO nanorods decorated reduced graphene oxide (RGO) nanocatalysts were prepared via a facile one-step hydrothermal method. The structure and morphology of the as-prepared samples were characterized by XRD, Raman spectroscopy, SEM, TEM, and X-ray photoelectron spectroscopy (XPS). The analysis results show that CuO nanorods were successfully deposited on the surface of RGO sheets with the length of 250–500 nm. The catalytic properties of the as-prepared catalysts for CO oxidation were evaluated by using a microreactor-gas chromatograph (GC) system. The as-prepared RGO–CuO nanocatalysts exhibited high activity for CO oxidation, and the 10 wt % reduced graphene oxide content catalyst can achieve CO total oxidation at 165 °C. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle N2O Decomposition over Cu–Zn/γ–Al2O3 Catalysts
Catalysts 2016, 6(12), 200; doi:10.3390/catal6120200
Received: 20 November 2016 / Revised: 5 December 2016 / Accepted: 6 December 2016 / Published: 12 December 2016
Cited by 1 | PDF Full-text (4888 KB) | HTML Full-text | XML Full-text
Abstract
Cu–Zn/γ–Al2O3 catalysts were prepared by the impregnation method. Catalytic activity was evaluated for N2O decomposition in a fixed bed reactor. The fresh and used catalysts were characterized by several techniques such as BET surface area, X-ray diffraction (XRD),
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Cu–Zn/γ–Al2O3 catalysts were prepared by the impregnation method. Catalytic activity was evaluated for N2O decomposition in a fixed bed reactor. The fresh and used catalysts were characterized by several techniques such as BET surface area, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Cu–Zn/γ–Al2O3 catalysts exhibit high activity and stability for N2O decomposition in mixtures simulating real gas from adipic acid production, containing N2O, O2, NO, CO2, and CO. Over the Cu–Zn/γ–Al2O3 catalysts, 100% of N2O conversion was obtained at about 601 °C at a gas hourly space velocity (GHSV) of 7200 h−1. Cu–Zn/γ–Al2O3 catalysts also exhibited considerably good durability, and no obvious activity loss was observed in the 100 h stability test. The Cu–Zn/γ–Al2O3 catalysts are promising for the abatement of this powerful greenhouse gas in the chemical industry, particularly in adipic acid production. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Open AccessArticle The Preparation of Cu-g-C3N4/AC Catalyst for Acetylene Hydrochlorination
Catalysts 2016, 6(12), 193; doi:10.3390/catal6120193
Received: 29 September 2016 / Revised: 29 November 2016 / Accepted: 29 November 2016 / Published: 5 December 2016
Cited by 2 | PDF Full-text (4847 KB) | HTML Full-text | XML Full-text
Abstract
A novel catalyst based on g-C3N4/activated carbon was prepared by adding CuCl2. The catalytic performance of the as-prepared catalyst was investigated in the acetylene hydrochlorination reaction. X-ray photoelectron spectroscopy, temperature programmed desorption, low temperature N2 adsorption/desorption
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A novel catalyst based on g-C3N4/activated carbon was prepared by adding CuCl2. The catalytic performance of the as-prepared catalyst was investigated in the acetylene hydrochlorination reaction. X-ray photoelectron spectroscopy, temperature programmed desorption, low temperature N2 adsorption/desorption (Brunauer–Emmett–Teller), and thermal gravity analysis showed that Cu-g-C3N4/AC significantly enhanced the catalytic performance of the original catalyst by increasing the relative pyrrolic N content. Cu-g-C3N4/AC also affected the adsorption of hydrogen chloride and acetylene, as well as inhibited the coke deposition during acetylene hydrochlorination. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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Review

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Open AccessFeature PaperReview Visible-Light-Active TiO2-Based Hybrid Nanocatalysts for Environmental Applications
Catalysts 2017, 7(4), 100; doi:10.3390/catal7040100
Received: 20 January 2017 / Revised: 14 March 2017 / Accepted: 22 March 2017 / Published: 25 March 2017
Cited by 3 | PDF Full-text (7351 KB) | HTML Full-text | XML Full-text
Abstract
Photocatalytic nanomaterials such as TiO2 are receiving a great deal of attention owing to their potential applications in environmental remediation. Nonetheless, the low efficiency of this class of materials in the visible range has, so far, hampered their large-scale application. The increasing
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Photocatalytic nanomaterials such as TiO2 are receiving a great deal of attention owing to their potential applications in environmental remediation. Nonetheless, the low efficiency of this class of materials in the visible range has, so far, hampered their large-scale application. The increasing demand for highly efficient, visible-light-active photocatalysts can be addressed by hybrid nanostructured materials in which two or more units, each characterised by peculiar physical properties, surface chemistry and morphology, are combined together into a single nano-object with unprecedented chemical–physical properties. The present review intends to focus on hybrid nanomaterials, based on TiO2 nanoparticles able to perform visible-light-driven photocatalytic processes for environmental applications. We give a brief overview of the synthetic approaches recently proposed in the literature to synthesise hybrid nanocrystals and discuss the potential applications of such nanostructures in water remediation, abatement of atmospheric pollutants (including NOx and volatile organic compounds (VOCs)) and their use in self-cleaning surfaces. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis for Environmental Remediation)
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