Catalysts

2749 KiB

Open AccessFeature PaperArticle

Mixed-Metal Semiconductor Anodes for Electrochemical Water Splitting and Reactive Chlorine Species Generation: Implications for Electrochemical Wastewater Treatment

by Su Young Ryu and Michael R. Hoffmann

Catalysts 2016, 6(4), 59; https://doi.org/10.3390/catal6040059 - 20 Apr 2016

Cited by 13 | Viewed by 7360

Abstract

A procedure for the preparation of semiconductor anodes using mixed-metal oxides bound together and protected with a TiO₂ nanoglue has been developed and tested in terms of the relative efficiencies of the oxygen evolution (OER), the reactive chlorine species evolution (RCS), and [...] Read more.

A procedure for the preparation of semiconductor anodes using mixed-metal oxides bound together and protected with a TiO₂ nanoglue has been developed and tested in terms of the relative efficiencies of the oxygen evolution (OER), the reactive chlorine species evolution (RCS), and the hydrogen evolution (HER) reactions. The composition of the first anode is a Ti metal substrate coated with IrTaO_x and overcoated with TiO₂ (P₂₅) that was mixed with TiO₂ nanogel, while the second anode consists of a Ti metal substrate coated with IrTaO_x and an over-coating layer of La-doped sodium tantalate, NaTaO₃:La. The experimental efficiencies for water splitting ranged from 62.4% to 67.5% for H₂ evolution and 40.6% to 60.0% for O₂ evolution. The corresponding over-potentials for the Ti/IrTa-TiO₂ and Ti/IrTa-NaTaO₃:La anodes coupled with stainless steel cathodes of the same dimensions were determined to be 437 mV and 367 mV for the OER, respectively, and 239 mV and 205 mV for RCS, respectively. The preparation procedure described herein should allow for easier production of large-surface area anodes at lower costs than standard methods. Full article

(This article belongs to the Special Issue Photocatalytic Water Splitting-1)

► Show Figures

Graphical abstract

4308 KiB

Open AccessArticle

Adsorption Performance of Methyl Violet via α-Fe₂O₃@Porous Hollow Carbonaceous Microspheres and Its Effective Regeneration through a Fenton-Like Reaction

by Zhiqing Tong, Pei Zheng, Bo Bai, Honglun Wang and Yourui Suo

Catalysts 2016, 6(4), 58; https://doi.org/10.3390/catal6040058 - 15 Apr 2016

Cited by 27 | Viewed by 5545

Abstract

α-Fe₂O₃@porous hollow carbonaceous microspheres (α-Fe₂O₃@PHCMs) were prepared through a combination of hydrothermal and calcination method. The novel α-Fe₂O₃@PHCMs integrated the adsorptive and catalytic performances and served as an inexpensive adsorbent to [...] Read more.

α-Fe₂O₃@porous hollow carbonaceous microspheres (α-Fe₂O₃@PHCMs) were prepared through a combination of hydrothermal and calcination method. The novel α-Fe₂O₃@PHCMs integrated the adsorptive and catalytic performances and served as an inexpensive adsorbent to rapidly remove cationic dye (methyl violet (MV)) from aqueous solution. Equilibrium studies indicated that the dye molecules obeyed Langmuir type of adsorption with the calculated maximum adsorption capacity of 539.8 mg∙g⁻¹ at 313.15 K. Kinetic data were better described by pseudo-second-order model and the thermodynamic studies illustrated that MV adsorption onto the composite was spontaneous, endothermic and occurred by physisorption. The Fenton-like process was found to be effective for the regeneration of the spent α-Fe₂O₃@PHCMs. The regeneration efficiency, as high as 88.0%, was still maintained after three consecutive adsorption-regeneration cycles. FTIR and XRD characterizations of the composite before and after adsorption-regeneration treatment showed that the Fenton-like process did not cause serious damage to the structure of composites. Full article

► Show Figures

Graphical abstract

2711 KiB

Open AccessArticle

Physico-Chemical and Catalytic Properties of Mesoporous CuO-ZrO₂ Catalysts

by Sulaiman N. Basahel, Mohamed Mokhtar, Edreese H. Alsharaeh, Tarek T. Ali, Hatem A. Mahmoud and Katabathini Narasimharao

Catalysts 2016, 6(4), 57; https://doi.org/10.3390/catal6040057 - 13 Apr 2016

Cited by 47 | Viewed by 7742

Abstract

Mesoporous CuO-ZrO₂ catalysts were prepared and calcined at 500 °C. The performance of the synthesized catalysts for benzylation of benzene using benzyl chloride was studied. The bare support (macroporous ZrO₂) offered 45% benzyl chloride conversion after reaction time of 10 [...] Read more.

Mesoporous CuO-ZrO₂ catalysts were prepared and calcined at 500 °C. The performance of the synthesized catalysts for benzylation of benzene using benzyl chloride was studied. The bare support (macroporous ZrO₂) offered 45% benzyl chloride conversion after reaction time of 10 h at 75 °C. Significant increase in benzyl chloride conversion (98%) was observed after CuO loading (10 wt. %) on porous ZrO₂ support. The conversion was decreased to 80% with increase of CuO loading to 20 wt. %. Different characterization techniques (XRD, Raman, diffuse reflectance UV-vis, N₂-physisorption, H₂-TPR, XPS and acidity measurements) were used to evaluate physico-chemical properties of CuO-ZrO₂ catalysts; the results showed that the surface and structural characteristics of the ZrO₂ phase as well as the interaction between CuO-ZrO₂ species depend strongly on the CuO content. The results also indicated that ZrO₂ support was comprised of monoclinic and tetragonal phases with macropores. An increase of the volume of monoclinic ZrO₂ phase was observed after impregnation of 10 wt. % of CuO; however, stabilization of tetragonal ZrO₂ phase was noticed after loading of 20 wt. % CuO. The presence of low-angle XRD peaks indicates that mesoscopic order is preserved in the calcined CuO-ZrO₂ catalysts. XRD reflections due to CuO phase were not observed in case of 10 wt. % CuO supported ZrO₂ sample; in contrast, the presence of crystalline CuO phase was observed in 20 wt. % CuO supported ZrO₂ sample. The mesoporous 10 wt. % CuO supported ZrO₂ catalyst showed stable catalytic activity for several reaction cycles. The observed high catalytic activity of this catalyst could be attributed to the presence of a higher number of dispersed interactive CuO (Cu²⁺-O-Zr⁴⁺) species, easy reducibility, and greater degree of accessible surface Lewis acid sites. Full article

► Show Figures

Graphical abstract

17058 KiB

Open AccessArticle

Upgrading V₂O₅-WO₃/TiO₂ deNOx Catalyst with TiO₂-SiO₂ Support Prepared from Ti-Bearing Blast Furnace Slag

by Tuyetsuong Tran, Jian Yu, Lina Gan, Feng Guo, Dinhtuan Phan and Guangwen Xu

Catalysts 2016, 6(4), 56; https://doi.org/10.3390/catal6040056 - 12 Apr 2016

Cited by 20 | Viewed by 7558

Abstract

The study is devoted to developing a rather high-efficiency NH₃-SCR (selective catalytic reduction) catalyst for NO_x removal using TiO₂-SiO₂ support made from blast furnace slag. Through adjusting hydrolytic pH value of TiOSO₄ solution obtained from acidolysis [...] Read more.

The study is devoted to developing a rather high-efficiency NH₃-SCR (selective catalytic reduction) catalyst for NO_x removal using TiO₂-SiO₂ support made from blast furnace slag. Through adjusting hydrolytic pH value of TiOSO₄ solution obtained from acidolysis of slag with 70 wt. % H₂SO₄, a series of TiO₂-SiO₂ mixed oxides was prepared to have different mass ratios of TiO₂ to SiO₂. The supports are further impregnated with V₂O₅ and WO₃ to make the SCR catalysts for NO_x removal. Characterizing the catalysts show that silica and unavoidable impurities in support prepared from slag were responsible for maintaining their mesoporous structure and the enhancements in the acidity and reducible form of active species on the catalyst surface, which thus rendered the catalysts to have higher NO_x reduction capability than catalyst using commercial TiO₂. Furthermore, the low-cost catalyst prepared from slag-based TiO₂ support possesses good stability, and strong resistance to SO₂ and H₂O poisoning, which are beneficial to practical deNO_x applications. Full article

► Show Figures

Figure 1

3144 KiB

Open AccessArticle

The Influence of the Hydrogen Pressure on Kinetics of the Canola Oil Hydrogenation on Industrial Nickel Catalyst

by Marcin Konkol, Waldemar Wróbel, Robert Bicki and Andrzej Gołębiowski

Catalysts 2016, 6(4), 55; https://doi.org/10.3390/catal6040055 - 7 Apr 2016

Cited by 25 | Viewed by 7081

Abstract

Canola oil was hydrogenated on an industrial nickel catalyst at 180 °C under a wide range of pressures from 1.5 to 21 bar(a). The effect of hydrogen pressure on the hydrogenation characteristics and fatty acids profile was investigated. The hydrogenation kinetics were described [...] Read more.

Canola oil was hydrogenated on an industrial nickel catalyst at 180 °C under a wide range of pressures from 1.5 to 21 bar(a). The effect of hydrogen pressure on the hydrogenation characteristics and fatty acids profile was investigated. The hydrogenation kinetics were described by a simplified three-step model including linolenic acid. The apparent rate constants for the particular reaction steps (hydrogenation, isomerization) k_x as well as rate constants k_x₀ and reaction orders in hydrogen were determined. The results reveal that with the increasing pressure an increase of values of all rate constants was observed, with the largest increase being observed for the rate constant of hydrogenation of monoenes to stearic acid (about 20 times). Moreover, with the increasing pressure the isomerization rate of cis dienes to trans dienes was found to become lower than the dienes hydrogenation rate. Analogously, the cis/trans monoenes isomerization rate was also found to decrease with the increasing pressure. The reaction orders of the hydrogenation steps with respect to hydrogen were in the range of 0.35 to 1.1. The kinetic model was verified by comparsion of predicted fatty acids contents with the experimental data of fatty acids profiles. It emerged that a simplified kinetic model proposed can be utilized to simulate the course of the hydrogenation process and concentrations of fatty acids at a certain iodine value. Full article

► Show Figures

Graphical abstract

5728 KiB

Open AccessArticle

Impact of Lubricant Additives on thePhysicochemical Properties and Activity of Three‐Way Catalysts

by Chao Xie, Todd J. Toops, Michael J. Lance, Jun Qu, Michael B. Viola, Samuel A. Lewis, Donovan N. Leonard and Edward W. Hagaman

Catalysts 2016, 6(4), 54; https://doi.org/10.3390/catal6040054 - 4 Apr 2016

Cited by 23 | Viewed by 6464

Abstract

As alternative lubricant anti‐wear additives are sought to reduce friction and improve overall fuel economy, it is important that these additives are also compatible with current emissions control catalysts. In the present work, an oil‐miscible phosphorous‐containing ionic liquid (IL), trihexyltetradecylphosphonium bis(2‐ethylhexyl) phosphate ([P [...] Read more.

As alternative lubricant anti‐wear additives are sought to reduce friction and improve overall fuel economy, it is important that these additives are also compatible with current emissions control catalysts. In the present work, an oil‐miscible phosphorous‐containing ionic liquid (IL), trihexyltetradecylphosphonium bis(2‐ethylhexyl) phosphate ([P₆₆₆₁₄][DEHP]), is evaluated for its impact on three‐way catalysts (TWC) and benchmarked against the industry standard zinc‐dialkyl‐dithio‐phosphate (ZDDP). The TWCs are aged in different scenarios: neat gasoline (no‐additive, or NA), gasoline+ZDDP, and gasoline+IL. The aged samples, along with the as‐received TWC, are characterized through various analytical techniques including catalyst reactivity evaluation in a bench‐flow reactor. The temperatures of 50% conversion (T50) for the ZDDP‐aged TWCs increased by 30, 24, and 25 °C for NO, CO, and C3H6, respectively, compared to the no‐additive case. Although the IL‐aged TWC also increased in T50 for CO and C3H6, it was notably less than ZDDP, 7 and 9 °C, respectively. Additionally, the IL‐aged samples had higher water‐gas‐shift reactivity and oxygen storage capacity than the ZDDP‐aged TWC. Characterization of the aged samples indicated the predominant presence of CePO₄ in the ZDDP‐aged TWC aged by ZDDP, while its formation was retarded in the case of IL where higher levels of AlPO₄ is observed. Thus, results in this work indicate that the phosphonium‐phosphate IL potentially has less adverse impact on TWC than ZDDP. Full article

(This article belongs to the Special Issue Automotive Emission Control Catalysts)

► Show Figures

Graphical abstract

159 KiB

Open AccessEditorial

Molecular Catalysis for Precise Olefin Polymerization and ROP 2015

by Carl Redshaw

Catalysts 2016, 6(4), 53; https://doi.org/10.3390/catal6040053 - 31 Mar 2016

Viewed by 3358

Abstract

The growth of emerging markets, particularly in the Far East, has fuelled the demand for new plastic materials.[...] Full article

(This article belongs to the Special Issue Molecular Catalysis for Precise Olefin Polymerization and ROP 2015)

3983 KiB

Open AccessArticle

Synthesis of Diethyl Carbonate from Carbon Dioxide, Propylene Oxide and Ethanol over KNO₃-CeO₂ and KBr-KNO₃-CeO₂ Catalysts

by Yanlou Wang, Dongdong Jia, Zhen Zhu and Yongyue Sun

Catalysts 2016, 6(4), 52; https://doi.org/10.3390/catal6040052 - 29 Mar 2016

Cited by 13 | Viewed by 6601

Abstract

One-pot syntheses of diethyl carbonate (DEC) from CO₂, propylene oxide and ethanol were carried out using different solid catalysts. The supercritical CO₂ extraction method was used to separate the liquid products and reactants from the catalysts after reaction. The KNO [...] Read more.

One-pot syntheses of diethyl carbonate (DEC) from CO₂, propylene oxide and ethanol were carried out using different solid catalysts. The supercritical CO₂ extraction method was used to separate the liquid products and reactants from the catalysts after reaction. The KNO₃-CeO₂ and KBr-KNO₃-CeO₂ were found to be active for the reaction after calcinations. The catalyst was also reusable. The thermodynamic properties of the reaction were also evaluated. The effects of various conditions, such as reaction time, amount of catalysts, molar ratio of the reactants, the composition and calcination temperature of the catalysts on the conversion and yields, were investigated, and the yield of DEC was about 13.0% with a selectivity of 38.5% over KBr-KNO₃-CeO₂. The yield of DEC was improved about 10-fold by using KBr-KNO₃-CeO₂ catalyst compared to CeO₂. Full article

► Show Figures

Graphical abstract

1944 KiB

Open AccessArticle

Hydrogenolysis of Glycerol to 1,2-Propanediol and Ethylene Glycol over Ru-Co/ZrO₂ Catalysts

by Jian Feng, Youquan Zhang, Wei Xiong, Hao Ding and Bai He

Catalysts 2016, 6(4), 51; https://doi.org/10.3390/catal6040051 - 25 Mar 2016

Cited by 26 | Viewed by 7111

Abstract

A series of ZrO₂ supported Ru-Co bimetallic catalysts were prepared and evaluated for the hydrogenolysis of glycerol. The Ru-Co/ZrO₂ bimetallic catalyst combines the advantages of both Ru and Co, exhibiting high activity and good selectivity to 1,2-propanediol. The X-ray diffraction (XRD) [...] Read more.

A series of ZrO₂ supported Ru-Co bimetallic catalysts were prepared and evaluated for the hydrogenolysis of glycerol. The Ru-Co/ZrO₂ bimetallic catalyst combines the advantages of both Ru and Co, exhibiting high activity and good selectivity to 1,2-propanediol. The X-ray diffraction (XRD) and TEM results show that higher calcination temperature leads to lower reducibility of cobalt oxides and larger metal particle size, which is responsible for the decrease of glycerol conversion. Increasing the reduction temperature causes an inhibition effect on the catalytic activity, but it is beneficial to promote the 1,2-propanediol selectivity. The low temperature (<300 °C) reduction can prevent the growth of metal particles, resulting in higher activity. Co oxide is an important component for the good performance of Ru-Co/ZrO₂. The reaction temperature, hydrogen pressure, and glycerol concentration have significant effects on the catalytic performance of the Ru-Co/ZrO₂ catalyst. Full article

► Show Figures

Figure 1

13564 KiB

Open AccessFeature PaperReview

New Trends in Oxidative Functionalization of Carbon–Hydrogen Bonds: A Review

by Georgiy B. Shul’pin

Catalysts 2016, 6(4), 50; https://doi.org/10.3390/catal6040050 - 24 Mar 2016

Cited by 167 | Viewed by 15538

Abstract

This review describes new reactions catalyzed by recently discovered types of metal complexes and catalytic systems (catalyst + co-catalyst). Works of recent years (mainly 2010–2016) devoted to the oxygenations of saturated, aromatic hydrocarbons and other carbon–hydrogen compounds are surveyed. Both soluble metal complexes [...] Read more.

This review describes new reactions catalyzed by recently discovered types of metal complexes and catalytic systems (catalyst + co-catalyst). Works of recent years (mainly 2010–2016) devoted to the oxygenations of saturated, aromatic hydrocarbons and other carbon–hydrogen compounds are surveyed. Both soluble metal complexes and solid metal compounds catalyze such transformations. Molecular oxygen, hydrogen peroxide, alkyl peroxides, and peroxy acids were used in these reactions as oxidants. Full article

(This article belongs to the Special Issue Catalytic Functionalization of C‒H Bonds)

► Show Figures

Graphical abstract

2101 KiB

Open AccessArticle

Efficient Dehydration of Fructose to 5-Hydroxy-methylfurfural Catalyzed by Heteropolyacid Salts

by Yanlei Song, Xincheng Wang, Yongshui Qu, Chongpin Huang, Yingxia Li and Biaohua Chen

Catalysts 2016, 6(4), 49; https://doi.org/10.3390/catal6040049 - 23 Mar 2016

Cited by 21 | Viewed by 5677

Abstract

5-Hydroxymethylfurfural (5-HMF), which is derived from numerous industrial biomass resources, has attracted attention in recent years due to its potential as a building block. In this paper, a range of heteropolyacid salts had been investigated for the dehydration of fructose to 5-HMF. CePW [...] Read more.

5-Hydroxymethylfurfural (5-HMF), which is derived from numerous industrial biomass resources, has attracted attention in recent years due to its potential as a building block. In this paper, a range of heteropolyacid salts had been investigated for the dehydration of fructose to 5-HMF. CePW₁₂O₄₀ demonstrated the best catalytic activity. Effects of fructose concentration, reaction temperature and reaction time on 5-HMF yield were investigated and optimised through a central composite design and response surface methodology. The optimal 5-HMF yield was 99.40% under the optimized reaction conditions of 5.48 mg/mL fructose loading, 158 °C temperature and 164 min reaction time. A kinetic analysis of the fructose conversion was also performed, and the activation energy and pre-exponential factor were obtained. Full article

(This article belongs to the Special Issue Catalytic Conversion of Biomass)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Catalysts, Volume 6, Issue 4 (April 2016) – 11 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI