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Catalysts, Volume 6, Issue 1 (January 2016)

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Editorial

Jump to: Research, Review

Open AccessEditorial Synthesis of Nanostructured Catalytic Materials from Microemulsions
Catalysts 2016, 6(1), 4; doi:10.3390/catal6010004
Received: 18 December 2015 / Accepted: 22 December 2015 / Published: 25 December 2015
Cited by 1 | PDF Full-text (161 KB) | HTML Full-text | XML Full-text
Abstract
Since the 1980s [1,2], colloidal systems such as microemulsions (ME) have been widely investigated, especially for the synthesis of nanomaterials for various applications.[...] Full article
(This article belongs to the Special Issue Synthesis of Nanostructured Catalytic Materials from Microemulsions)
Open AccessEditorial Catalytic Removal of Volatile Organic Compounds
Catalysts 2016, 6(1), 7; doi:10.3390/catal6010007
Received: 18 December 2015 / Revised: 29 December 2015 / Accepted: 29 December 2015 / Published: 5 January 2016
Cited by 2 | PDF Full-text (138 KB) | HTML Full-text | XML Full-text
Abstract
The degradation of air quality by the release of volatile organic compounds (VOCs) into the air particularly harms human health and our environment. [...] Full article
Open AccessEditorial A New Year of Catalysts
Catalysts 2016, 6(1), 16; doi:10.3390/catal6010016
Received: 13 January 2016 / Accepted: 14 January 2016 / Published: 19 January 2016
PDF Full-text (471 KB) | HTML Full-text | XML Full-text
Abstract
Welcome to a new year of Catalysts, an international, peer-reviewed open access journal. [...] Full article
Open AccessEditorial Acknowledgement to Reviewers of Catalysts in 2015
Catalysts 2016, 6(1), 18; doi:10.3390/catal6010018
Received: 21 January 2016 / Accepted: 21 January 2016 / Published: 21 January 2016
PDF Full-text (191 KB) | HTML Full-text | XML Full-text
Abstract
The editors of Catalysts would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...] Full article

Research

Jump to: Editorial, Review

Open AccessArticle Catalytic Conversion of Glucose into 5-Hydroxymethylfurfural by Hf(OTf)4 Lewis Acid in Water
Catalysts 2016, 6(1), 1; doi:10.3390/catal6010001
Received: 6 November 2015 / Revised: 13 December 2015 / Accepted: 14 December 2015 / Published: 23 December 2015
Cited by 7 | PDF Full-text (729 KB) | HTML Full-text | XML Full-text
Abstract
A series of Lewis acidic metal salts were used for glucose dehydration to 5-hydroymethylfurfural (HMF) in water. Effect of valence state, ionic radii of Lewis acidic cation, and the type of anions on the catalytic performance have been studied systematically. The experimental results
[...] Read more.
A series of Lewis acidic metal salts were used for glucose dehydration to 5-hydroymethylfurfural (HMF) in water. Effect of valence state, ionic radii of Lewis acidic cation, and the type of anions on the catalytic performance have been studied systematically. The experimental results showed that the valence state played an important role in determining catalytic activity and selectivity. It was found that a higher glucose conversion rate and HMF selectivity could be obtained over high valent Lewis acid salts, where the ionic radii of these Lewis acidic metal salts are usually relatively small. Analysis on the effect of the anions of Lewis acid salts on the catalytic activity and the selectivity suggested that a higher glucose conversion and HMF selectivity could be readily obtained with Cl. Furthermore, the recyclability of high valence state Lewis acid salt was also studied, however, inferior catalytic performance was observed. The deactivation mechanism was speculated to be the fact that high valence state Lewis acid salt was comparatively easier to undergo hydrolysis to yield complicated metal aqua ions with less catalytic activity. The Lewis acidic activity could be recovered by introducing a stoichiometric amount of hydrochloric acid (HCl) to the catalytic before the reaction. Full article
(This article belongs to the Special Issue Catalytic Conversion of Biomass)
Open AccessArticle Phosphotungstate-Based Ionic Silica Nanoparticles Network for Alkenes Epoxidation
Catalysts 2016, 6(1), 2; doi:10.3390/catal6010002
Received: 28 October 2015 / Revised: 13 December 2015 / Accepted: 14 December 2015 / Published: 24 December 2015
Cited by 1 | PDF Full-text (2268 KB) | HTML Full-text | XML Full-text
Abstract
An inorganic-organic porous silica network catalyst was prepared by linking silica nanoparticles using ionic liquid and followed by anion-exchange with phosphotungstate. Characterization methods of FT-IR, TG, SEM, TEM, BET, etc., were carried out to have a comprehensive insight into the catalyst. The
[...] Read more.
An inorganic-organic porous silica network catalyst was prepared by linking silica nanoparticles using ionic liquid and followed by anion-exchange with phosphotungstate. Characterization methods of FT-IR, TG, SEM, TEM, BET, etc., were carried out to have a comprehensive insight into the catalyst. The catalyst was used for catalyzing cyclooctene epoxidation with high surface area, high catalytic activity, and convenient recovery. The conversion and selectivity of epoxy-cyclooctene could both reach over 99% at 70 °C for 8 h using hydrogen peroxide (H2O2) as an oxidant, and acetonitrile as a solvent when the catalyst was 10 wt. % of cyclooctene. Full article
(This article belongs to the Special Issue Surface Chemistry and Catalysis) Printed Edition available
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Open AccessArticle Hybrids of Gold Nanoparticles with Core-Shell Hyperbranched Polymers: Synthesis, Characterization, and Their High Catalytic Activity for Reduction of 4-Nitrophenol
Catalysts 2016, 6(1), 3; doi:10.3390/catal6010003
Received: 6 November 2015 / Revised: 6 December 2015 / Accepted: 18 December 2015 / Published: 25 December 2015
Cited by 4 | PDF Full-text (1612 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Hyperbranched core-shell structure can be constructed by the modification of hyperbranched polyethylenimine (HPEI) with different amide shells. Functionalized HPEI with acetic amide (HPEI-ACAm), propionic amide (HPEI-PRAm), butyric amide (HPEI-BUAm) and isobutyric amide (HPEI-IBAm) shells have been successfully prepared and used as protectors for
[...] Read more.
Hyperbranched core-shell structure can be constructed by the modification of hyperbranched polyethylenimine (HPEI) with different amide shells. Functionalized HPEI with acetic amide (HPEI-ACAm), propionic amide (HPEI-PRAm), butyric amide (HPEI-BUAm) and isobutyric amide (HPEI-IBAm) shells have been successfully prepared and used as protectors for gold nanoparticles (AuNPs). Novel AuNP composites were obtained through the non-covalent interaction between HPEI-XXAm and gold nanoparticles (XXAm represents ACAm, PRAm, BUAm or IBAm). The resulted AuNP composites can catalyze the reduction reaction of 4-nitrophenol by NaBH4. Interestingly, the catalytic activity of the AuNPs mainly depends on the structure of protectors and the degree of carbon chain arrangement denseness, which should affect the diffusivity of the reactants. In addition, the order of reaction rate is HPEI10K-IBAm0.80 > HPEI10K-ACAm0.80 > HPEI10K-PRAm0.82 > HPEI10K-BUAm0.83. It was found that the increase of the concentrations of the capping HPEI-XXAm polymers can enhance both the reaction rate and the turnover frequency (TOF) values. Furthermore, the reaction rate was accelerated with increasing the reaction temperature for AuNPs-HPEI10K-ACAm0.80 and AuNPs-HPEI10K-PRAm0.82 systems. Interestingly, the reaction rate was accelerated with elevating reaction temperature at the beginning but reached a plateau or decreased sharply for AuNPs-HPEI10K-IBAm0.80 and AuNPs-HPEI10K-BUAm0.82 systems, owing to the thermoresponsivity of the corresponding AuNP composites. As a consequence, the catalytic activity could be controlled by adjusting the different shells of the hyperbranched polyethylenimine. Full article
Open AccessArticle Electrocatalytic Oxidation of Cellulose to Gluconate on Carbon Aerogel Supported Gold Nanoparticles Anode in Alkaline Medium
Catalysts 2016, 6(1), 5; doi:10.3390/catal6010005
Received: 25 November 2015 / Revised: 24 December 2015 / Accepted: 25 December 2015 / Published: 30 December 2015
Cited by 3 | PDF Full-text (2141 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The development of high efficient and low energy consumption approaches for the transformation of cellulose is of high significance for a sustainable production of high value-added feedstocks. Herein, electrocatalytic oxidation technique was employed for the selective conversion of cellulose to gluconate in alkaline
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The development of high efficient and low energy consumption approaches for the transformation of cellulose is of high significance for a sustainable production of high value-added feedstocks. Herein, electrocatalytic oxidation technique was employed for the selective conversion of cellulose to gluconate in alkaline medium by using concentrated HNO3 pretreated carbon aerogel (CA) supported Au nanoparticles as anode. Results show that a high gluconate yield of 67.8% and sum salts yield of 88.9% can be obtained after 18 h of electrolysis. The high conversion of cellulose and high selectivity to gluconate could be attributed to the good dissolution of cellulose in NaOH solution which promotes its hydrolysis, the surface oxidized CA support and Au nanoparticles catalyst which possesses high amount of active sites. Moreover, the bubbled air also plays important role in the enhancement of cellulose electrocatalytic conversion efficiency. Lastly, a probable mechanism for electrocatalytic oxidation of cellulose to gluconate in alkaline medium was also proposed. Full article
(This article belongs to the Special Issue Catalytic Conversion of Biomass)
Open AccessArticle Hydrogenation of Levulinic Acid over Nickel Catalysts Supported on Aluminum Oxide to Prepare γ-Valerolactone
Catalysts 2016, 6(1), 6; doi:10.3390/catal6010006
Received: 19 October 2015 / Revised: 22 December 2015 / Accepted: 23 December 2015 / Published: 30 December 2015
Cited by 7 | PDF Full-text (1812 KB) | HTML Full-text | XML Full-text
Abstract
Four types of nickel catalysts supported on aluminum oxide (Ni/Al2O3) with different nickel loadings were synthesized using the co-precipitation method and were used for the hydrogenation of levulinic acid (LA) to prepare γ-valerolactone (GVL). The synthesized Ni/Al2O
[...] Read more.
Four types of nickel catalysts supported on aluminum oxide (Ni/Al2O3) with different nickel loadings were synthesized using the co-precipitation method and were used for the hydrogenation of levulinic acid (LA) to prepare γ-valerolactone (GVL). The synthesized Ni/Al2O3 catalysts exhibited excellent catalytic activity in dioxane, and the activity of the catalysts was excellent even after being used four times in dioxane. The catalytic activity in dioxane as a solvent was found to be superior to the activity in water. Nitrogen physisorption, X-ray diffraction, and transmission electron microscopy were employed to characterize the fresh and used catalysts. The effects of the nickel loading, temperature, hydrogen pressure, and substrate/catalyst ratio on the catalytic activity were investigated. Full article
(This article belongs to the Special Issue Catalytic Conversion of Biomass)
Open AccessArticle Effects of Dealumination and Desilication of Beta Zeolite on Catalytic Performance in n-Hexane Cracking
Catalysts 2016, 6(1), 8; doi:10.3390/catal6010008
Received: 11 November 2015 / Revised: 24 December 2015 / Accepted: 29 December 2015 / Published: 5 January 2016
Cited by 6 | PDF Full-text (4561 KB) | HTML Full-text | XML Full-text
Abstract
Catalytic cracking of n-hexane to selectively produce propylene on Beta zeolite was carried out. The H-Beta (HB) (Si/Al = 77) zeolite showed higher catalytic stability and propylene selectivity than the Al-rich HB (Si/Al = 12), due to its smaller number of acid
[...] Read more.
Catalytic cracking of n-hexane to selectively produce propylene on Beta zeolite was carried out. The H-Beta (HB) (Si/Al = 77) zeolite showed higher catalytic stability and propylene selectivity than the Al-rich HB (Si/Al = 12), due to its smaller number of acid sites, especially Lewis acid sites (LAS). However, catalytic stability and propylene selectivity in high n-hexane conversions were still not satisfactory. After dealumination with HNO3 treatment, catalytic stability was improved and propylene selectivity during high n-hexane conversions was increased. On the other hand, catalytic stability was not improved after desilication with NaOH treatment, although mesopores were formed. This may be related to the partially destroyed structure. However, propylene selectivity in high n-hexane conversions was increased after alkali treatment. We successfully found that the catalytic stability was improved and the propylene selectivity in high n-hexane conversions was further increased after the NaOH treatment followed by HNO3 treatment. This is due to the decrease in the number of acid sites and the increase in mesopores which are beneficial to the diffusion of coke precursor. Full article
(This article belongs to the Special Issue Zeolite Catalysis) Printed Edition available
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Open AccessArticle Characterization and Catalytic Activity of Mn-Co/TiO2 Catalysts for NO Oxidation to NO2 at Low Temperature
Catalysts 2016, 6(1), 9; doi:10.3390/catal6010009
Received: 7 November 2015 / Revised: 27 December 2015 / Accepted: 5 January 2016 / Published: 11 January 2016
Cited by 8 | PDF Full-text (2019 KB) | HTML Full-text | XML Full-text
Abstract
A series of Mn-Co/TiO2 catalysts were prepared by wet impregnation method and evaluated for the oxidation of NO to NO2. The effects of Co amounts and calcination temperature on NO oxidation were investigated in detail. The catalytic oxidation ability in
[...] Read more.
A series of Mn-Co/TiO2 catalysts were prepared by wet impregnation method and evaluated for the oxidation of NO to NO2. The effects of Co amounts and calcination temperature on NO oxidation were investigated in detail. The catalytic oxidation ability in the temperature range of 403–473 K was obviously improved by doping cobalt into Mn/TiO2. These samples were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and hydrogen temperature programmed reduction (H2-TPR). The results indicated that the formation of dispersed Co3O4·CoMnO3 mixed oxides through synergistic interaction between Mn-O and Co-O was directly responsible for the enhanced activities towards NO oxidation at low temperatures. Doping of Co enhanced Mn4+ formation and increased chemical adsorbed oxygen amounts, which also accelerated NO oxidation. Full article
(This article belongs to the Special Issue Surface Chemistry and Catalysis) Printed Edition available
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Open AccessArticle Catalytic Performance of Lanthanum Vanadate Catalysts in Ammoxidation of 2-Methylpyrazine
Catalysts 2016, 6(1), 10; doi:10.3390/catal6010010
Received: 25 November 2015 / Revised: 6 January 2016 / Accepted: 7 January 2016 / Published: 12 January 2016
Cited by 3 | PDF Full-text (1311 KB) | HTML Full-text | XML Full-text
Abstract
The influence of reaction conditions on the catalytic performance of lanthanum vanadate (La0.1V0.9Ox) catalyst in the ammoxidation of 2-methylpyrazine (MP) to 2-cyanopyarazine (CP) has been investigated. This novel catalytic material exhibited remarkably good performance with very high
[...] Read more.
The influence of reaction conditions on the catalytic performance of lanthanum vanadate (La0.1V0.9Ox) catalyst in the ammoxidation of 2-methylpyrazine (MP) to 2-cyanopyarazine (CP) has been investigated. This novel catalytic material exhibited remarkably good performance with very high space-time-yields (STY) of CP. The reaction parameters such as the effect of temperature, gas hourly space velocity (GHSV) and all other reaction variables (e.g., NH3, air, and MP feed rates) on the catalytic performance were explored and optimized. For example, an increase in MP feed rate from 2 to >16 mmol/h led to decreased conversion of MP but increased the STY of CP significantly. Optimal performance was achieved when the reaction temperature was 420 °C and the molar ratio of 2-MP, ammonia, air, H2O and N2 in the feed gas was set to 1:7:26:13:22. Under these optimal reaction conditions, the catalyst showed a MP conversion of ~100%, CP selectivity of 86%, and STY of >500 gCP/(kgcat∙h). On the other hand, the formation of pyrazine (Py) as a by-product was found to be high when the NH3:MP ratio was lower at increased contact time. This suggests possible differences in the reaction mechanism pathways with respect to feed composition over La0.1V0.9Ox catalysts. Full article
(This article belongs to the Special Issue Catalysts for Selective Oxidation)
Open AccessArticle Ni Catalysts Supported on Modified Alumina for Diesel Steam Reforming
Catalysts 2016, 6(1), 11; doi:10.3390/catal6010011
Received: 12 November 2015 / Revised: 18 December 2015 / Accepted: 7 January 2016 / Published: 13 January 2016
Cited by 5 | PDF Full-text (1536 KB) | HTML Full-text | XML Full-text
Abstract
Nickel catalysts are the most popular for steam reforming, however, they have a number of drawbacks, such as high propensity toward coke formation and intolerance to sulfur. In an effort to improve their behavior, a series of Ni-catalysts supported on pure and La-,
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Nickel catalysts are the most popular for steam reforming, however, they have a number of drawbacks, such as high propensity toward coke formation and intolerance to sulfur. In an effort to improve their behavior, a series of Ni-catalysts supported on pure and La-, Ba-, (La+Ba)- and Ce-doped γ-alumina has been prepared. The doped supports and the catalysts have been extensively characterized. The catalysts performance was evaluated for steam reforming of n-hexadecane pure or doped with dibenzothiophene as surrogate for sulphur-free or commercial diesel, respectively. The undoped catalyst lost its activity after 1.5 h on stream. Doping of the support with La improved the initial catalyst activity. However, this catalyst was completely deactivated after 2 h on stream. Doping with Ba or La+Ba improved the stability of the catalysts. This improvement is attributed to the increase of the dispersion of the nickel phase, the decrease of the support acidity and the increase of Ni-phase reducibility. The best catalyst of the series doped with La+Ba proved to be sulphur tolerant and stable for more than 160 h on stream. Doping of the support with Ce also improved the catalytic performance of the corresponding catalyst, but more work is needed to explain this behavior. Full article
(This article belongs to the Special Issue Surface Chemistry and Catalysis) Printed Edition available
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Open AccessArticle High Efficient Hydrogenation of Lignin-Derived Monophenols to Cyclohexanols over Pd/γ-Al2O3 under Mild Conditions
Catalysts 2016, 6(1), 12; doi:10.3390/catal6010012
Received: 4 December 2015 / Revised: 29 December 2015 / Accepted: 31 December 2015 / Published: 13 January 2016
Cited by 7 | PDF Full-text (7340 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The catalytic hydrogenation of lignin-derived monophenols with high efficiency and selectivity is important for the sustainable production of chemicals and fuels. Here, Pd/γ-Al2O3 was prepared via impregnation and used as catalyst for the hydrogenation of phenols to cyclohexanols under mild
[...] Read more.
The catalytic hydrogenation of lignin-derived monophenols with high efficiency and selectivity is important for the sustainable production of chemicals and fuels. Here, Pd/γ-Al2O3 was prepared via impregnation and used as catalyst for the hydrogenation of phenols to cyclohexanols under mild conditions in aqueous solution. 3 wt. % Pd/γ-Al2O3 exhibited good catalytic activity for the selective hydrogenation of 4-ethylphenol into 4-ethylcyclohexanol, and a conversion of 100% with selectivity of 98.9% was achieved at 60 °C for 12 h. Other lignin-derived monophenolic model compounds such as 4-methyl phenol and 4-propyl phenol could be hydrogenated into cyclohexanols selectively under optimal conditions. Moreover, the Pd/γ-Al2O3 catalyst displayed good activity for the hydrogenation of the mixture of monophenols directly derived from raw biomass system to cyclohexanols as the main products, and was favorable for the depolymerization of lignin oligomers under milder conditions. Pd/γ-Al2O3 catalyst showed good water resistance and stability after recycling four times. This result might provide a promising approach to selectively producing cyclohexanol directly from raw biomass material under mild conditions in aqueous solutions. Full article
(This article belongs to the Special Issue Catalytic Conversion of Biomass)
Open AccessCommunication The Fabrication of Ga2O3/ZSM-5 Hollow Fibers for Efficient Catalytic Conversion of n-Butane into Light Olefins and Aromatics
Catalysts 2016, 6(1), 13; doi:10.3390/catal6010013
Received: 7 November 2015 / Revised: 21 December 2015 / Accepted: 29 December 2015 / Published: 15 January 2016
Cited by 5 | PDF Full-text (3244 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study, the dehydrogenation component of Ga2O3 was introduced into ZSM-5 nanocrystals to prepare Ga2O3/ZSM-5 hollow fiber-based bifunctional catalysts. The physicochemical features of as-prepared catalysts were characterized by means of XRD, BET, SEM, STEM, NH
[...] Read more.
In this study, the dehydrogenation component of Ga2O3 was introduced into ZSM-5 nanocrystals to prepare Ga2O3/ZSM-5 hollow fiber-based bifunctional catalysts. The physicochemical features of as-prepared catalysts were characterized by means of XRD, BET, SEM, STEM, NH3-TPD, etc., and their performances for the catalytic conversion of n-butane to produce light olefins and aromatics were investigated. The results indicated that a very small amount of gallium can cause a marked enhancement in the catalytic activity of ZSM-5 because of the synergistic effect of the dehydrogenation and aromatization properties of Ga2O3 and the cracking function of ZSM-5. Compared with Ga2O3/ZSM-5 nanoparticles, the unique hierarchical macro-meso-microporosity of the as-prepared hollow fibers can effectively enlarge the bifunctionality by enhancing the accessibility of active sites and the diffusion. Consequently, Ga2O3/ZSM-5 hollow fibers show excellent catalytic conversion of n-butane, with the highest yield of light olefins plus aromatics at 600 °C by 87.6%, which is 56.3%, 24.6%, and 13.3% higher than that of ZSM-5, ZSM-5 zeolite fibers, and Ga2O3/ZSM-5, respectively. Full article
(This article belongs to the Special Issue Zeolite Catalysis) Printed Edition available
Open AccessArticle Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides
Catalysts 2016, 6(1), 14; doi:10.3390/catal6010014
Received: 13 December 2015 / Revised: 30 December 2015 / Accepted: 30 December 2015 / Published: 15 January 2016
Cited by 3 | PDF Full-text (1589 KB) | HTML Full-text | XML Full-text
Abstract
A series of metal cation modified layered-double hydroxides (LDHs) and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH
[...] Read more.
A series of metal cation modified layered-double hydroxides (LDHs) and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism. Full article
(This article belongs to the Special Issue Catalysts for Selective Oxidation)
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Open AccessArticle Pyrazole Supported Zinc(II) Benzoates as Catalysts for the Ring Opening Copolymerization of Cyclohexene Oxide and Carbon Dioxide
Catalysts 2016, 6(1), 17; doi:10.3390/catal6010017
Received: 29 September 2015 / Revised: 8 January 2016 / Accepted: 11 January 2016 / Published: 20 January 2016
Cited by 2 | PDF Full-text (2197 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The bis(pyrazole)zinc(II) benzoate complexes bis(3,5-diphenylpyrazole)zinc(II) benzoate (1), bis(3,5-diphenylpyrazole)zinc(II) 3,5-dinitrobenzoate (2), bis(3,5-diphenylpyrazole)zinc(II) 4-hydroxybenzoate (3), and bis(3,5-di-tert-butylpyrazole)zinc(II) 2-chlorobenzoate (4) were synthesized from the reaction of 3,5-diphenylpyrazole (L1) or 3,5-di-tert-butylpyrazole (L2
[...] Read more.
The bis(pyrazole)zinc(II) benzoate complexes bis(3,5-diphenylpyrazole)zinc(II) benzoate (1), bis(3,5-diphenylpyrazole)zinc(II) 3,5-dinitrobenzoate (2), bis(3,5-diphenylpyrazole)zinc(II) 4-hydroxybenzoate (3), and bis(3,5-di-tert-butylpyrazole)zinc(II) 2-chlorobenzoate (4) were synthesized from the reaction of 3,5-diphenylpyrazole (L1) or 3,5-di-tert-butylpyrazole (L2), zinc(II) acetate and the appropriate benzene carboxylic acid. The molecular structure of complex 2 confirmed that these zinc(II) benzoate complexes adopt a 4-coordinate tetrahedral geometry. All four complexes were screened as catalysts for the copolymerization of carbon dioxide (CO2) and cyclohexene oxide (CHO) and were found to be active for the formation of poly(cyclohexene carbonate) (PCHC) at CO2 pressures as low as 1.0 MPa under solvent-free conditions and without the use of a co-catalyst. At some reaction condition, most of the catalysts produced PCHC with high carbonate content of up to 98% and a good amount of cyclic cyclohexene carbonate (CCHC). The copolymers produced have low to moderate molecular weights (5200–12300 g/mol) and with polydispersity indices that vary from 1.19 to 2.50. Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectra (MALDI-TOF MS) of these copolymers showed they have benzoate and hydroxyl end groups. Full article
(This article belongs to the Special Issue Molecular Catalysis for Precise Olefin Polymerization and ROP 2015)
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Review

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Open AccessReview A Review of Surface Analysis Techniques for the Investigation of the Phenomenon of Electrochemical Promotion of Catalysis with Alkaline Ionic Conductors
Catalysts 2016, 6(1), 15; doi:10.3390/catal6010015
Received: 30 November 2015 / Revised: 6 January 2016 / Accepted: 6 January 2016 / Published: 18 January 2016
Cited by 5 | PDF Full-text (1755 KB) | HTML Full-text | XML Full-text
Abstract
Electrochemical Promotion of Catalysis (EPOC) with alkali ionic conductors has been widely studied in literature due to its operational advantages vs. alkali classical promotion. This phenomenon allows to electrochemically control the alkali promoter coverage on a catalyst surface in the course of
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Electrochemical Promotion of Catalysis (EPOC) with alkali ionic conductors has been widely studied in literature due to its operational advantages vs. alkali classical promotion. This phenomenon allows to electrochemically control the alkali promoter coverage on a catalyst surface in the course of the catalytic reaction. Along the study of this phenomenon, a large variety of in situ and ex situ surface analysis techniques have been used to investigate the origin and mechanism of this kind of promotion. In this review, we analyze the most important contributions made on this field which have clearly evidenced the presence of adsorbed alkali surface species on the catalyst films deposited on alkaline solid electrolyte materials during EPOC experiments. Hence, the use of different surface analysis techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning photoelectron microscopy (SPEM), or scanning tunneling microscopy (STM), led to a better understanding of the alkali promoting effect, and served to confirm the theory of electrochemical promotion on this kind of catalytic systems. Given the functional similarities between alkali electrochemical and chemical promotion, this review aims to bring closer this phenomenon to the catalysis scientific community. Full article
(This article belongs to the Special Issue Surface Chemistry and Catalysis) Printed Edition available
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