Hydrogen by steam reforming of ethanol over Co-Mg incorporated novel mesoporous alumina catalysts in tubular and microwave reactors

Bio-ethanol is an excellent hydrogen carrier with a good potential to be used as a resource for on-board hydrogen production. In this work, a set of new Co incorporated mesoporous alumina (MA) catalysts, which were modified with Mg, were synthesized and tested in steam reforming of ethanol. Results proved that, the synthesis route of these materials had a highly significant effect on their catalytic performances. Co@Mg-MA and Co-Mg-MA catalysts, which were prepared by direct addition of Mg into the mesoporous alumina framework, gave the best performance in steam reforming of ethanol, with very high hydrogen yield values. This was concluded to be due to the presence of Co and CoO phases within the structures of these catalysts. However, Co-Mg@MA and Co@MA catalysts, which were prepared by the impregnation of Co/Mg or Co into mesoporous alumina, mainly catalyzed ethanol dehydration reaction to yield ethylene, rather than steam reforming. This was concluded to be due to the high Lewis acidity of these catalysts and the presence of cobalt aluminate phase in their structure. Activity tests of the synthesized catalysts were made both in a tubular reactor which was conductively heated and also in a focused-microwave system. Better energy utilization and more stable performance with much less coke formation were achieved in the focused-microwave reactor than the conventionally heated system

Sorption-Enhanced Reforming of Ethanol over Ni- and Co-Incorporated MCM-41 Type Catalysts

Ni- and Co-incorporated MCM-41 type mesoporous materials with Ni/Si and Co/Si molar ratios of 0.12 were synthesized, characterized, and tested in both steam reforming of ethanol (SRE) and sorption-enhanced steam reforming of ethanol (SESRE) reactions. Characterization results showed that Co and Ni were successfully incorporated and well-dispersed in the mesoporous MCM-41 support. Ni- and Co-incorporated MCM-41 catalysts had surface area values of 449.0 and 303.6 m(2)/g, respectively. They also had narrow pore size distributions, with average pore diameters of 2.2 and 1.98 nm, respectively. SESRE results obtained with these catalysts showed that in situ capture of CO2 during ethanol reforming reaction significantly enhanced hydrogen yield in the temperature range of 500-600 degrees C. The catalytic performance of Ni-incorporated MCM-41 was much better than the Co-incorporated MCM-41, in hydrogen production by ethanol reforming. The highest hydrogen yield value obtained over the Ni-incorporated MCM-41 catalyst was achieved at 600 degrees C as 5.6 in SESRE reaction. This was similar to 94% of the maximum possible hydrogen yield value of 6.0

Steam reforming of ethanol with zirconia incorporated mesoporous silicate supported catalysts

Steam reforming of ethanol is a promising route for the production of high purity hydrogen. Ni impregnated zirconia, with high chemical and thermal stability and high water adsorption-dissociation capability is an attractive catalyst for this reaction. In the present study, mesoporous zirconia and high surface area zirconia/silicate structured materials, such as Zr-SBA-15 and Zr-MCM-41, were synthesized following hydrothermal routes, using different surfactants as the structure directing templates. Surface area values of Ni impregnated mesoporous Zr-SBA-15 and Zr-MCM-41 catalysts with molar Zr/Si ratios of 0.13 and 0.45 were 515 and 338 m(2)/g, respectively. Ethanol reforming tests performed with these catalysts, in the temperature range of 550-650 degrees C, proved the potential of these materials to achieve very high hydrogen yields, over 90% of the maximum yield value of 6 mol per mole of ethanol reacted. Type of support material, Ni distribution and cluster size over the catalyst, reaction temperature and steam to ethanol ratio were found to have strong influence on coke formation and stability of hydrogen yield. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Formation of carbonaceous deposits on Pd-based hydrodechlorination catalysts: Vibrational spectroscopy investigations over Pd/Al2O3 and Pd/SOMS

The widespread utilization and commercialization of hydrodechlorination (HDC) over Pd-based catalysts as a remediation technique has been impeded because of catalyst deactivation problems such as formation of carbonaceous deposits under the reductive environment of HDC. In this study, we investigated the use of a novel animated material, swellable organically-modified silica (SOMS), as a catalyst scaffold for HDC of trichloroethylene (TCE) to develop a catalytic system resistant to carbon formation. The state of aggregation of adsorbed TCE on Pd/SOMS was characterized. It was found that the unique nature of SOMS scaffold caused condensation of adsorbents in the SOMS matrix. This is of particular importance considering the fact that the increase of local concentration of reactants due to condensation may enhance the kinetics of catalytic reactions. To determine the resistance to the formation of carbonaceous materials under reaction conditions, in-situ vibrational spectroscopy experiments (diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and laser Raman spectroscopy) were undertaken over Pd-incorporated SOMS in the absence and presence of water vapor in the reactant stream. The commonly used HDC catalyst Pd/Al2O3 was also studied for comparison purposes. Formation of carbonaceous deposits of different nature were observed over Pd/Al2O3 whereas no detectable carbon formation was observed over Pd/SOMS. It was confirmed that surface hydroxyl groups which are in basic character act as coking agents. The carbon formation resistant behavior of Pd/SOMS is closely related to the nature and low concentration of surface hydroxyl groups

Caesarean operation in two farmed red deer (Cervus elaphus)

In this case, a caesarean section was performed on 2 red deer aged 4 and 7 who underwent dystocia. When the deer were brought to our clinic, they had been in labour for 6 h and 1 day, respectively, and the calves were dead. The foetal forefeet were found hanging from the vulva at the general examination. Deer l's parturition was human-assisted but the outcome was not good and it was decided to operate on the animal. in deer 2, parturition was taking too long and so it was decided to operate immediately. The deer were sedated and anaesthetised by infiltration of the left paralumbar fossa in order to perform the caesarean operations. The caesarean operations were performed successfully and both red deer are still alive. For a postoperative period of 5 days, an antibiotic and vitamin combination was administered to both deer. It is concluded that for red deer in whom dystocia is common a caesarean operation can be the treatment of choice

Swellable Organically Modified Silica (SOMS): A Novel Support for Aqueous Phase Hydrodechlorination of Trichloroethylene

This study focuses on the use of swellable organically modified silica (SOMS) as a catalyst support for aqueous-phase hydrodechlorination of trichloroethylene. SOMS is extremely hydrophobic and swells volumetrically when contacted with organics. These properties should help overcome the disadvantages associated with the commercial catalyst (Pd/Al2O3), such as deactivation by anions

Aqueous-phase hydrodechlorination of trichloroethylene over Pd-based swellable organically-modified silica (SOMS): Catalyst deactivation due to chloride anions

Swellable-organically modified silica (SOMS) has been demonstrated to be an efficient catalyst scaffold for catalytic treatment of water contaminated with trichloroethylene (TCE). In this study, deactivation characteristics of Pd-incorporated SOMS for aqueous-phase hydrodechlorination (HDC) of TCE were investigated. Pd/SOMS catalysts were exposed to highly-concentrated chloride solutions (up to 1 M NaCl or 0.01 M HCl) to examine the deactivation resistant behavior of Pd/SOMS. The commonly used HDC catalyst Pd/Al2O3 was also studied for comparison purposes. Pd/SOMS and Pd/Al2O3 in their pristine and treated states were tested for aqueous-phase HDC of TCE and characterized by several techniques including N2 physisorption, inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy, extended X-ray absorption fine structure spectroscopy (EXAFS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed CO. The aqueous-phase treatments had a pronounced adverse effect on the textural properties of Pd/Al2O3, although the effect was independent of the type of the chloride precursor, NaCl or HCl. Treating Pd/Al2O3 with chloride-containing solutions lowered the catalytic activity due to formation of Pd-Cl complexes and active metal leaching. The leached Pd obtained from the treatment solution was shown to be inactive for aqueous-phase HDC of TCE. While Pd/Al2O3 underwent severe deactivation due to the chloride treatments, Pd/SOMS exhibited resistance to chloride deactivation and metal leaching. The chloride treatments did not impact the textural properties of Pd/SOMS. The achieved deactivation resistance was attributed to the novel characteristics of the SOMS support

Aqueous-Phase Hydrodechlorination of Trichloroethylene over Pd-Based Swellable Organically Modified Silica: Catalyst Deactivation Due to Sulfur Species

One of the problems of catalytic water treatment systems is that sulfur-containing species present in contaminated water have a detrimental effect on the catalytic performance because of strong interactions of sulfur species with active metal sites. In order to address these problems, our research has focused on developing a poison-resistant catalytic system by using a novel material, namely, swellable organically modified silica (SOMS), as a catalyst scaffold. Our previous investigations demonstrated that the developed system was resistant to chloride poisoning, active metal leaching, and carbon deposition under reaction conditions. This study examines the sulfur tolerance of the developed catalytic system for hydrodechlorination (HDC) of trichloroethylene (TCE) by subjecting Pd-incorporated samples to different sulfur species, including sulfates (SO42–), bisulfides (HS–), and hydrogen sulfide (H2S). The pristine and sulfur-treated catalysts were then tested for aqueous- and gas-phase HDC of TCE and characterized by several techniques, including N2 physisorption, X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure spectroscopy (EXAFS), and temperature-programmed reaction (TPrxn) with H2. The investigations were also performed on Pd/Al2O3, a commercially used HDC catalyst, to have a basis for comparison. The activity and characterization results revealed that Pd/Al2O3 underwent deactivation due to exposure to sulfur-containing compounds. Pd/SOMS, however, exhibited better resistance to aqueous sulfates, bisulfides, and gas-phase H2S. In addition, the removal of sulfur species from completely poisoned catalysts was found to be more facile in Pd/SOMS than Pd/Al2O3. The tolerance of Pd/SOMS to sulfur poisoning was attributed to stem from the novel characteristics of SOMS, such as swelling ability and extreme hydrophobicity