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Catalysts, Volume 2, Issue 1 (March 2012), Pages 1-222

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Research

Jump to: Review

Open AccessArticle Gold/Iron Carbonyl Clusters for Tailored Au/FeOx Supported Catalysts
Catalysts 2012, 2(1), 1-23; doi:10.3390/catal2010001
Received: 6 October 2011 / Revised: 1 December 2011 / Accepted: 6 December 2011 / Published: 21 December 2011
Cited by 11 | PDF Full-text (1617 KB) | HTML Full-text | XML Full-text
Abstract
A novel preparation method was developed for the preparation of gold/iron oxide supported catalysts using the bimetallic carbonyl cluster salts [NEt4]4[Au4Fe4(CO)16] and [NEt4][AuFe4(CO)16] as precursors of highly
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A novel preparation method was developed for the preparation of gold/iron oxide supported catalysts using the bimetallic carbonyl cluster salts [NEt4]4[Au4Fe4(CO)16] and [NEt4][AuFe4(CO)16] as precursors of highly dispersed nanoparticles over different supports. A series of catalysts with different metal loadings were prepared and tested in the complete oxidation of dichlorobenzene, toluene, methanol and in the preferential oxidation of CO in the presence of H2 (PROX) as model reactions. The characterization by BET, XRD, TEM, H2-TPR, ICP-AES and XPS point out the way the nature of the precursors and the thermal treatment conditions affected the dispersion of the active phase and their catalytic activity in the studied reactions. Full article
(This article belongs to the Special Issue Gold Catalysts)
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Open AccessArticle The Influence of Base Metal (M) Oxidation State in Au-M-O/TiO2 Systems on Their Catalytic Activity in Carbon Monoxide Oxidation
Catalysts 2012, 2(1), 38-55; doi:10.3390/catal2010038
Received: 6 October 2011 / Revised: 5 November 2011 / Accepted: 7 December 2011 / Published: 22 December 2011
Cited by 2 | PDF Full-text (1072 KB) | HTML Full-text | XML Full-text
Abstract
Base metal promoted gold/titania catalysts were synthesized, characterized and tested in CO oxidation reaction. Catalysts containing dopant metals in higher oxidation states exhibited higher activity than catalysts containing dopants in reduced states. The activity of fresh catalysts promoted by Cu, Fe and Ni
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Base metal promoted gold/titania catalysts were synthesized, characterized and tested in CO oxidation reaction. Catalysts containing dopant metals in higher oxidation states exhibited higher activity than catalysts containing dopants in reduced states. The activity of fresh catalysts promoted by Cu, Fe and Ni was similar to the unpromoted one, but treatment in reducing and oxidizing atmospheres revealed the supremacy of the copper promoted catalyst. The sequential deposition method proved to be better than the co-deposition—precipitation method. An attempt to explain these differences using XPS, FTIR and H2 TPR was performed. Full article
(This article belongs to the Special Issue Gold Catalysts)
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Open AccessArticle Hydrogen Evolution from Napiergrass by the Combination of Biological Treatment and a Pt-Loaded TiO2-Photocatalytic Reaction
Catalysts 2012, 2(1), 56-67; doi:10.3390/catal2010056
Received: 11 November 2011 / Revised: 1 December 2011 / Accepted: 12 December 2011 / Published: 22 December 2011
Cited by 6 | PDF Full-text (335 KB) | HTML Full-text | XML Full-text
Abstract
Ethanol and pentose were produced from lignocellulosic napiergrass by the simultaneous saccharification and fermentation process (SSF) using hydrolytic enzyme and S. Cerevisiae. After the ethanol was removed, the pentose solution was subjected to photocatalytic hydrogen evolution with Pt-loaded TiO2 under UV-irradiation.
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Ethanol and pentose were produced from lignocellulosic napiergrass by the simultaneous saccharification and fermentation process (SSF) using hydrolytic enzyme and S. Cerevisiae. After the ethanol was removed, the pentose solution was subjected to photocatalytic hydrogen evolution with Pt-loaded TiO2 under UV-irradiation. This process converted 100 g of napiergrass into 12.3 g of ethanol and 1.76 g of hydrogen whose total combustion energy of (H) was 615 kJ. This was close to the H (639 kJ) of the pentose (13.6 g) and hexose (27.4 g) obtained by the cellulose-saccharification of 100 g of napiergrass. Full article
(This article belongs to the Special Issue Catalysts for Biomass Conversion)
Open AccessArticle One-Pot Liquid-Phase Catalytic Conversion of Ethanol to 1-Butanol over Aluminium Oxide—The Effect of the Active Metal on the Selectivity
Catalysts 2012, 2(1), 68-84; doi:10.3390/catal2010068
Received: 21 September 2011 / Revised: 24 November 2011 / Accepted: 4 January 2012 / Published: 13 January 2012
Cited by 37 | PDF Full-text (1507 KB) | HTML Full-text | XML Full-text
Abstract
Direct catalytic valorization of bioethanol to 1-butanol over different alumina supported catalysts was studied. Thirteen (13) heterogeneous catalysts were screened in search for the optimal material composition for direct one-pot conversion of ethanol to 1-butanol. For the most promising catalyst, a 25% ethanol
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Direct catalytic valorization of bioethanol to 1-butanol over different alumina supported catalysts was studied. Thirteen (13) heterogeneous catalysts were screened in search for the optimal material composition for direct one-pot conversion of ethanol to 1-butanol. For the most promising catalyst, a 25% ethanol conversion with 80% selectivity (among liquid carbon products) to 1-butanol could be reached at 250 °C. Additionally, the reaction kinetics and mechanisms were further investigated upon use of the most suitable catalyst candidate. Full article
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Open AccessArticle Hydrogenation of Anthracene in Supercritical Carbon Dioxide Solvent Using Ni Supported on Hβ-Zeolite Catalyst
Catalysts 2012, 2(1), 85-100; doi:10.3390/catal2010085
Received: 26 October 2011 / Revised: 20 December 2011 / Accepted: 11 January 2012 / Published: 30 January 2012
Cited by 4 | PDF Full-text (354 KB) | HTML Full-text | XML Full-text
Abstract
Catalytic hydrogenation of anthracene was studied over Ni supported on Hβ-zeolite catalyst under supercritical carbon dioxide (sc-CO2) solvent. Hydrogenation of anthracene in sc-CO2 yielded 100% conversion at 100 °C, which is attributed to the reduced mass transfer limitations, and increased
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Catalytic hydrogenation of anthracene was studied over Ni supported on Hβ-zeolite catalyst under supercritical carbon dioxide (sc-CO2) solvent. Hydrogenation of anthracene in sc-CO2 yielded 100% conversion at 100 °C, which is attributed to the reduced mass transfer limitations, and increased solubility of H2 and substrate in the reaction medium. The total pressure of 7 MPa was found to be optimum for high selectivity of octahydroanthracene (OHA). The conversion and selectivity for OHA increased with an increase in H2 partial pressure, which is attributed to higher concentration of hydrogen atoms at higher H2 pressures. The selectivity reduced the pressure below 7 MPa because of enhanced desorption of the tetrahydro-molecules and intermediates from Ni active sites, due to higher solubility of the surface species in sc-CO2. The selectivity of OHA increased with the increase in catalyst weight and reaction time. The rate of hydrogenation of anthracene was compared with that found for napthalene and phenanthrene. The use of acetonitrile as co-solvent or expanded liquid with CO2 decreased the catalytic activity. Full article
(This article belongs to the Special Issue Feature Papers)
Open AccessArticle Influence of Gold on Ce-Zr-Co Fluorite-Type Mixed Oxide Catalysts for Ethanol Steam Reforming
Catalysts 2012, 2(1), 121-138; doi:10.3390/catal2010121
Received: 9 January 2012 / Revised: 18 January 2012 / Accepted: 27 January 2012 / Published: 3 February 2012
Cited by 7 | PDF Full-text (494 KB) | HTML Full-text | XML Full-text
Abstract
The effect of gold presence on carbon monoxide oxidation and ethanol steam reforming catalytic behavior of two Ce-Zr-Co mixed oxides catalysts with a constant Co charge and different Ce/Zr ratios was investigated. The Ce-Zr-Co mixed oxides were obtained by the pseudo sol-gel like
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The effect of gold presence on carbon monoxide oxidation and ethanol steam reforming catalytic behavior of two Ce-Zr-Co mixed oxides catalysts with a constant Co charge and different Ce/Zr ratios was investigated. The Ce-Zr-Co mixed oxides were obtained by the pseudo sol-gel like method, based on metallic propionates polymerization and thermal decomposition, whereas the gold-supported Ce-Zr-Co mixed oxides catalysts were prepared using the direct anionic exchange. The catalysts were characterized using XRD, TPR, and EDXS-TEM. The presence of Au in doped Ce-Zr-Co oxide catalyst decreases the temperature necessary to reduce the cobalt and the cerium loaded in the catalyst and favors a different reaction pathway, improving the acetaldehyde route by ethanol dehydrogenation, instead of the ethylene route by ethanol dehydration or methane re-adsorption, thus increasing the catalytic activity and selectivity into hydrogen. Full article
(This article belongs to the Special Issue Gold Catalysts)
Open AccessArticle Production of Bio-Hydrogenated Diesel by Hydrotreatment of High-Acid-Value Waste Cooking Oil over Ruthenium Catalyst Supported on Al-Polyoxocation-Pillared Montmorillonite
Catalysts 2012, 2(1), 171-190; doi:10.3390/catal2010171
Received: 1 December 2011 / Revised: 19 January 2012 / Accepted: 7 February 2012 / Published: 14 February 2012
Cited by 11 | PDF Full-text (408 KB) | HTML Full-text | XML Full-text
Abstract
Waste cooking oil with a high-acid-value (28.7 mg-KOH/g-oil) was converted to bio-hydrogenated diesel by a hydrotreatment process over supported Ru catalysts. The standard reaction temperature, H2 pressure, liquid hourly space velocity (LHSV), and H2/oil ratio were 350 °C, 2 MPa,
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Waste cooking oil with a high-acid-value (28.7 mg-KOH/g-oil) was converted to bio-hydrogenated diesel by a hydrotreatment process over supported Ru catalysts. The standard reaction temperature, H2 pressure, liquid hourly space velocity (LHSV), and H2/oil ratio were 350 °C, 2 MPa, 15.2 h–1, and 400 mL/mL, respectively. Both the free fatty acids and the triglycerides in the waste cooking oil were deoxygenated at the same time to form hydrocarbons in the hydrotreatment process. The predominant liquid hydrocarbon products (98.9 wt%) were n-C18H38, n-C17H36, n-C16H34, and n-C15H32 when a Ru/SiO2 catalyst was used. These long chain normal hydrocarbons had high melting points and gave the liquid hydrocarbon product over Ru/SiO2 a high pour point of 20 °C. Ru/H-Y was not suitable for producing diesel from waste cooking oil because it formed a large amount of C5–C10 gasoline-ranged paraffins on the strong acid sites of HY. When Al-polyoxocation-pillared montmorillonite (Al13-Mont) was used as a support for the Ru catalyst, the pour point of the liquid hydrocarbon product decreased to −15 °C with the conversion of a significant amount of C15–C18 n-paraffins to iso-paraffins and light paraffins on the weak acid sites of Al13-Mont. The liquid product over Ru/Al13-Mont can be expected to give a green diesel for current diesel engines because its chemical composition and physical properties are similar to those of commercial petro-diesel. A relatively large amount of H2 was consumed in the hydrogenation of unsaturated C=C bonds and the deoxygenation of C=O bonds in the hydrotreatment process. A sulfided Ni-Mo/Al13-Mont catalyst also produced bio-hydrogenated diesel by the hydrotreatment process but it showed slow deactivation during the reaction due to loss of sulfur. In contrast, Ru/Al13-Mont did not show catalyst deactivation in the hydrotreatment of waste cooking oil after 72 h on-stream because the waste cooking oil was not found to contain sulfur-containing compounds. Full article
(This article belongs to the Special Issue Catalysts for Biomass Conversion)

Review

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Open AccessReview The Art of Manufacturing Gold Catalysts
Catalysts 2012, 2(1), 24-37; doi:10.3390/catal2010024
Received: 17 October 2011 / Revised: 21 November 2011 / Accepted: 7 December 2011 / Published: 21 December 2011
Cited by 17 | PDF Full-text (1600 KB) | HTML Full-text | XML Full-text
Abstract
Gold has been considered as an active catalyst only when suitable techniques of preparation provided high metal dispersion. A comprehensive survey of the different methods now available for preparing active gold catalysts is reported with particular attention to the role of the supporting
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Gold has been considered as an active catalyst only when suitable techniques of preparation provided high metal dispersion. A comprehensive survey of the different methods now available for preparing active gold catalysts is reported with particular attention to the role of the supporting material in determining catalyst characteristics. Full article
(This article belongs to the Special Issue Gold Catalysts)
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Open AccessReview Monometallic Supported Gold Catalysts in Organic Transformations: Ring Making and Ring Breaking
Catalysts 2012, 2(1), 101-120; doi:10.3390/catal2010101
Received: 10 October 2011 / Revised: 19 December 2011 / Accepted: 9 January 2012 / Published: 1 February 2012
Cited by 3 | PDF Full-text (970 KB) | HTML Full-text | XML Full-text
Abstract
Supported gold catalysts are highly active in oxidation reactions. Beside the most frequently studied CO oxidation, they are readily applied in the epoxidation of more or less complex olefinic compounds using air or oxygen directly or other oxidants like peroxides of various kinds.
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Supported gold catalysts are highly active in oxidation reactions. Beside the most frequently studied CO oxidation, they are readily applied in the epoxidation of more or less complex olefinic compounds using air or oxygen directly or other oxidants like peroxides of various kinds. Less frequently though, the reverse reaction, ring opening with single or double C–O scission is also investigated. These and other ring making and breaking reactions are reviewed, and the catalytic roles of gold species are described. Full article
(This article belongs to the Special Issue Gold Catalysts)
Open AccessReview Oxidation Catalysts for Elemental Mercury in Flue Gases—A Review
Catalysts 2012, 2(1), 139-170; doi:10.3390/catal2010139
Received: 29 December 2011 / Revised: 18 January 2012 / Accepted: 1 February 2012 / Published: 13 February 2012
Cited by 23 | PDF Full-text (514 KB) | HTML Full-text | XML Full-text
Abstract
The removal of mercury from flue gases in scrubbers is greatly facilitated if the mercury is present as water-soluble oxidized species. Therefore, increased mercury oxidation upstream of scrubber devices will improve overall mercury removal. For this purpose heterogeneous catalysts have recently attracted a
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The removal of mercury from flue gases in scrubbers is greatly facilitated if the mercury is present as water-soluble oxidized species. Therefore, increased mercury oxidation upstream of scrubber devices will improve overall mercury removal. For this purpose heterogeneous catalysts have recently attracted a great deal of interest. Selective catalytic reduction (SCR), noble metal and transition metal oxide based catalysts have been investigated at both the laboratory and plant scale with this objective. A review article published in 2006 covers the progress in the elemental mercury (Hgel) catalytic oxidation area. This paper brings the review in this area up to date. To this end, 110 papers including several reports and patents are reviewed. For each type of catalyst the possible mechanisms as well as the effect of flue gas components on activity and stability are examined. Advantages and main problems are analyzed. The possible future directions of catalyst development in this environmental research area are outlined. Full article
(This article belongs to the Special Issue Feature Papers)
Open AccessReview Catalytic Technologies for Biodiesel Fuel Production and Utilization of Glycerol: A Review
Catalysts 2012, 2(1), 191-222; doi:10.3390/catal2010191
Received: 19 January 2012 / Revised: 11 February 2012 / Accepted: 16 February 2012 / Published: 22 March 2012
Cited by 26 | PDF Full-text (886 KB) | HTML Full-text | XML Full-text
Abstract
More than 10 million tons of biodiesel fuel (BDF) have been produced in the world from the transesterification of vegetable oil with methanol by using acid catalysts (sulfuric acid, H2SO4), alkaline catalysts (sodium hydroxide, NaOH or potassium hydroxide, KOH),
[...] Read more.
More than 10 million tons of biodiesel fuel (BDF) have been produced in the world from the transesterification of vegetable oil with methanol by using acid catalysts (sulfuric acid, H2SO4), alkaline catalysts (sodium hydroxide, NaOH or potassium hydroxide, KOH), solid catalysts and enzymes. Unfortunately, the price of BDF is still more expensive than that of petro diesel fuel due to the lack of a suitable raw material oil. Here, we review the best selection of BDF production systems including raw materials, catalysts and production technologies. In addition, glycerol formed as a by-product needs to be converted to useful chemicals to reduce the amount of glycerol waste. With this in mind, we have also reviewed some recent studies on the utilization of glycerol. Full article
(This article belongs to the Special Issue Catalysts for Biomass Conversion)

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