Low-Temperature Selective Catalytic Reduction (SCR) of NOx with n-Octane Using Solvent-Free Mechanochemically Prepared Ag/Al2O3 Catalysts

Low-temperature (<200 degrees C) hydrocarbon selective catalytic reduction of NOx has been achieved for the first time in the absence of hydrogen using a solvent-free mechanochemically prepared Ag/Al2O3 catalyst. Catalysts prepared by this ball-milling method show a remarkable increase in activity for the reduction of nitrogen oxides with octane by lowering the light-off temperature by up to 150 degrees C compared with a state-of-the-art 2 wt %Ag/Al2O3 catalyst prepared by wet impregnation. The best catalyst prepared from silver oxide showed 50% NOx conversion at 240 degrees C and 99%, at 302 degrees C. The increased activity is not due to an increased surface area of the support, but may be associated with a change in.the'defeet structure of the alumina surface, leading to the formation of the small silver clusters necessary for the activation of the octane without leading to total combustion. On the other hand, since one possible role of hydrogen is to remove inhibiting species from the silver, we cannot exclude some change in the chemical properties of the silver as a result of the ball-milling treatment.

Isolation and Characterisation of 1-Alkyl-3- Methylimidazolium Chloride Ionic Liquid-Tolerant and Biodegrading Marine Bacteria

The aim of this study was to isolate and identify marine-derived bacteria which exhibited high tolerance to, and an ability to biodegrade, 1-alkyl-3-methylimidazolium chloride ionic liquids. The salinity and hydrocarbon load of some marine environments may induce selective pressures which enhance the ability of microbes to grow in the presence of these liquid salts. The isolates obtained in this study generally showed a greater ability to grow in the presence of the selected ionic liquids compared to microorganisms described previously, with two marine-derived bacteria, Rhodococcus erythropolis and Brevibacterium sanguinis growing in concentrations exceeding 1 M 1-ethyl-3-methylimidazolium chloride. The ability of these bacteria to degrade the selected ionic liquids was assessed using High Performance Liquid Chromatography (HPLC), and three were shown to degrade the selected ionic liquids by up to 59% over a 63-day test period. These bacterial isolates represent excellent candidates for further potential applications in the bioremediation of ionic liquid-containing waste or following accidental environmental exposure.

Galactic Bulge PNe:Carbon molecules in oxygen-rich environments

Galactic bulge planetary nebulae show evidence of mixed chemistry with emission from both silicate dust and PAHs. This mixed chemistry is unlikely to be related to carbon dredge up, as third dredge-up is not expected to occur in the low mass bulge stars. We show that the phenomenon is widespread, and is seen in 30 nebulae out of our sample of 40. A strong correlation is found between strength of the PAH bands and morphology, in particular, the presence of a dense torus. A chemical model is presented which shows that hydrocarbon chains can form within oxygen-rich gas through gas-phase chemical reactions. We conclude that the mixed chemistry phenomenon occurring in the galactic bulge planetary nebulae is best explained through hydrocarbon chemistry in an UV-irradiated, dense torus. © 2012 International Astronomical Union.

Spatial autocorrelation in the response of soft-bottom marine benthos to gas extraction activities: The case of amphipods in the Ionian Sea

The spatial distributions of marine fauna and of pollution are both highly structured, and thus the resulting high levels of autocorrelation may invalidate conclusions based on classical statistical approaches. Here we analyse the close correlation observed between proxies for the disturbance associated with gas extraction activities and amphipod distribution patterns around four hydrocarbon platforms. We quantified the amount of variation independently accounted for by natural environmental variables, proxies for the disturbance caused by platforms, and spatial autocorrelation. This allowed us to demonstrate how each of these three factors significantly affects the community structure of amphipods. Sophisticated statistical techniques are required when taking into account spatial autocorrelation: nevertheless our data demonstrate that this approach not only enables the formulation of robust statistical inferences but also provides a much deeper understanding of the subtle interactions between human disturbance and natural factors affecting the structure of marine invertebrates communities. (C) 2012 Elsevier Ltd. All rights reserved.

Biomonitoring of polybrominated diphenyl ether (PBDE) pollution: A field study

Polybrominated diphenyl ethers (PBDEs) and cytochrome P450 enzyme activities were investigated in European eels (Anguilla anguilla) collected from seven sites in a coastal lagoon in the north-western Mediterranean Sea, Orbetello lagoon (Italy). Twelve PBDE congeners were measured in muscle and two CYP1A enzyme activities, 7-ethoxyresorufin-O-deethylase (EROD) and benzo(a)pyrene monooxygenase (BP (a)PMO), were investigated in liver microsomal fraction in order to obtain insights into the health of the lagoon environment. PBDE muscle levels were low and the most abundant congeners were 2,2',4,4'-tetrabronnodiphenylether (BDE-47), 2,2',4,4',5,5'-hexaBDE (BDE-153) and 2,2',4,5'-tetraBDE (BDE-49). EROD and B(a)PMO activities were also low and no differences were observed between eels from different sites. Multivariate analysis (PCA) did not indicate correlations between PBDEs and either P450 activities. (c) 2008 Elsevier Inc. All rights reserved.

Phase Equilibria of Binary and Ternary Systems Containing ILs, Dodecane, and Cyclohexanecarboxylic Acid

This paper reports both the binary and ternary phase behavior of ionic liquids for extracting cyclohexanecarboxylic acid (CCA) from dodecane. This system is a model for the extraction of acids representative of naphthenic acids found in crude oils. In order to develop an effective ternary liquid-liquid extraction system the preliminary selection of ionic liquids was based on CCA miscibility and the dodecane immiscibility with selected ILs. A wide range of ILs based on different cations, anions, cation alkyl-chain length, as well as the effect of temperature on the overall fluid phase behavior is reported. Factors such as variation of cation group, anion effect, alkyl-chain length, and temperature all impact the extraction to various degrees. The largest effects were found to be the lipophilicity of the IL cation and the co-ordination ability of the anion. While CCA capacity increased with lipophilicity of the cation, as did the dodecane. Highly coordinating anions such as trifluoroacetate and triflate demonstrated that highly efficient extraction could be obtained producing favorable tie-lines in the ternary phase diagram. Overall, this study demonstrates that ILs can selectively extract acids from hydrocarbon streams and offers possible treatment solutions for problems associated with the processing of high acid crude oils.

A fast transient kinetic study of the effect of H-2 on the selective catalytic reduction of NOx with octane using isotopically labelled (NO)-N-15

The H-2-assisted hydrocarbon selective catalytic reduction (HC-SCR) of NO, was investigated using fast transient kinetic analysis coupled with isotopically labelled (NO)-N-15. This allowed monitoring of the evolution of products and reactants during switches of H-2 in and out of the SCR reaction mix. The results obtained with a time resolution of less than 1 s showed that the effect on the reaction of the removal or addition of H-2 was essentially instantaneous. This is consistent with the view that H-2 has a direct chemical effect on the reaction mechanism rather than a secondary one through the formation of "active" Ag clusters. The effect of H-2 partial pressure was investigated at 245 degrees C, it was found that increasing partial pressure of H-2 resulted in increasing conversion of NO and octane. It was also found that the addition of H-2 at 245 degrees C had different effects on the product distribution depending on its partial pressure. The change of the nitrogen balance over time during switches in and out of hydrogen showed that significant quantities of N-containing species were stored when hydrogen was introduced to the system. The positive nitrogen balance on removal of H-2 from the gas phase showed that these stored species continued to react after removal of hydrogen to form N-2. (c) 2006 Elsevier Inc. All rights reserved.

Water-hydrophobic compound interactions with the microbial cell

The structural interactions of biological macromolecules, their biochemical activities and, ultimately, the metabolic function of cellular systems are dependent upon weak inter- and intra-molecular forces such as hydrogen bonds, Van der Waals forces, and the hydrophobic effect. Water molecules, and those of hydrophobic substances such as hydrocarbons, can take part in and/or modify these interactions and thereby determine the operational and structural stability of the microbial cell and its macromolecular systems. We explain how the cytosol, plasma membrane and the extracellular solution form a material and energetic continuum; and discuss the behavior of hydrophobic substances of extracellular origin as they migrate into the plasma membrane and into the cell's interior. The adverse effects of substances with a log P octanol-water =2, that partition into the hydrophobic domains of biological macromolecules, are discussed in relation to microbial cell function; and we speculate whether the cellular stress that they induce is symmetrical or asymmetrical in nature. In the context of the microbial environment, we take a situational-functional approach to consider how hydrophobic stressors interact with the microbial cell, and what types of evasion tactics microbes can employ to minimize their inhibitory activities. Finally, we discuss the ecological implications of hydrocarbon-induced cellular stress for microbial systems.

Process for removing metals from hydrocarbons

The present invention relates to a process for the removal of mercury from a mercury- containing hydrocarbon fluid feed using specifically selected ionic liquids comprising, contacting the mercury-containing hydrocarbon fluid feed with an ionic liquid having the formula[Cat+][M+][X-] and separating from the ionic liquid a hydrocarbon fluid product having a reduced mercury content compared to the mercury-containing fluid feed.

Catalyst distribution and carbon nanotube morphology in multilayer forests by mixed CVD processes

Carbon nanotubes can be grown as forests of aligned fibers on a substrate with a catalyst coated prior to or added during synthesis. A major process interruption can initiate the growth of second and successive layers of forest on top or at the base of the existing layers which are thereby lifted up. We report on the generation of multilayer CNT forests where the first forest is generated either by catalyst coinjection (CCI) of ferrocene with hydrocarbon (xylene) or by catalyst predeposition (CPD) of iron followed with hydrocarbon (acetylene). Subsequent layers are then produced by CCI alone to give uniform (all CCI) or mixed (CPD and CCI) structures to study the distribution of the iron catalyst and CNT morphology and to determine whether the CPD forest templates or otherwise influences the growth of subsequent CCI forests. The bottom-up base growth of second and subsequent CCI forests is reaction rate controlled. CCI multilayer forests accumulate catalyst (iron) in a variety of distinct locations. A pre-existing CPD forest modifies subsequent CCI forest initiation, morphology, and catalyst distribution but does not itself accumulate catalyst or change appearance. © 2009 American Chemical Society.

Assessing the surface modifications following the mechanochemical preparation of a Ag/Al2O3 selective catalytic reduction catalyst

The surface modification of a mechanochemically prepared Ag/Al O catalyst compared with catalysts prepared by standard wet impregnated methods has been probed using two-dimensional T -T NMR correlations, HO temperature programmed desorption (TPD) and DRIFTS. The catalysts were examined for the selective catalytic reduction of NO using n-octane in the presence and absence of H. Higher activities were observed for the ball milled catalysts irrespective of whether H was added. This higher activity is thought to be related to the increased affinity of the catalyst surface towards the hydrocarbon relative to water, following mechanochemical preparation, resulting in higher concentrations of the hydrocarbon and lower concentrations of water at the surface. DRIFTS experiments demonstrated that surface isocyanate was formed significantly quicker and had a higher surface concentration in the case of the ball milled catalyst which has been correlated with the stronger interaction of the n-octane with the surface. This increased interaction may also be the cause of the reduced activation barrier measured for this catalyst compared with the wet impregnated system. The decreased interaction of water with the surface on ball milling is thought to reduce the effect of site blocking whilst still providing a sufficiently high surface concentration of water to enable effective hydrolysis of the isocyanate to form ammonia and, thereafter, N. This journal is © The Royal Society of Chemistry.

Investigating the promotional effect of methanol on the low temperature SCR reaction on Ag/Al2O3

Methanol has been shown to promote the hydrocarbon selective catalytic reduction of NO with octane and toluene over 2wt% Ag/AlO catalyst for the first time. In order to understand its role in the reaction fast transient kinetic methods and in situ DRIFTS analysis have been used. The catalytic activity tests showed that the addition of methanol to the HC-SCR reaction results in a significant improvement in the low temperature activity of a Ag/AlO catalyst, despite the fact that methanol on its own is not reactive for the HC-SCR reaction. This promotional effect of methanol is dependent on the concentration of added methanol and is not necessarily associated with a higher concentration of reductant in the SCR feed. The fast transient kinetic analysis has shown that at each temperature the addition of methanol enhances the conversions of both NO and octane and the production of N with high selectivity in comparison with those observed with n-octane or toluene alone. This phenomenon is similar to the effect of H which may be associated with the release of hydrogen and ammonia during the transient switches at 250 and 300°C. Together with the fast transient experiments, the DRIFTS results showed that NCO species are formed when introducing methanol to the n-octane-SCR feed while CN species are removed/consumed from the surfaces of the Ag catalyst. These NCO species formed by adding methanol may play a vital role in promoting the catalytic activity of NO reduction and methanol itself can be an in situ source for hydrogen formation, which subsequently enhances the SCR reaction. © 2014 Elsevier B.V.

Designing and understanding permanent microporosity in liquids

Standard microporous materials are typically crystalline solids that exhibit a regular array of cavities of uniform size and shape. Packing and directional bonding between molecular building blocks give rise to interstitial pores that confer size and shape-specific sorption properties to the material. In the liquid state interstitial cavities are transient. However, permanent and intrinsic "pores'' can potentially be built into the structure of the molecules that constitute the liquid. With the aid of computer simulations we have designed, synthesised and characterised a series of liquids composed of hollow cage-like molecules, which are functionalised with hydrocarbon chains to make them liquid at accessible temperatures. Experiments and simulations demonstrate that chain length and size of terminal chain substituents can be used to tune, within certain margins, the permanence of intramolecular cavities in such neat liquids. Simulations identify a candidate "porous liquid'' in which 30% of the cages remain empty in the liquid state. Absorbed methane molecules selectively occupy these empty cavities.

Inhibitory Effect of Phosphonium-Based Ionic Liquids on Coal Oxidation

To develop a chemical inhibitor that can efficiently suppress coal oxidation, nine tetraalkylphosphonium-based ionic liquids (ILs) and one imidazolium-based IL [1-allyl-3-methylimidazolium chloride ([AMIm]Cl)] were examined as additives. These ILs were used to treat and investigate the inhibitory effect on the oxidation activity and the structure of lignite coal. Characterization using thermogravimetric analysis showed that phosphonium-based ILs are able to inhibit coal oxidation up to 400 degrees C with the tributylethylphosphonium diethylphosphate ([P-4,P-4,P-4,P-2][DEP]) found to be the most effective. In contrast to the tetraalkylphosphonium-based ILs, inhibition using [AMIm]Cl was only found to be effective at temperatures below 250 degrees C, indicating that the tetraallcylphosphonium-based ILs may be more suitable for the future application of suppressing coal spontaneous combustion over a wide range of temperatures. Fourier transform infrared spectroscopic data showed that the various functional groups change in the coal following IL treatment, which are a decrease in the minerals and hydrogen bonds in all treated coals, while decreased aliphatic hydrocarbon and increased carbonyl bonds only appeared in some samples. During the oxidation of coal, the decomposition of aliphatic hydrocarbon groups is inhibited and the formation of carbonyl groups is delayed, so that the evolved gas concentration decreased, as shown by the temperature-programmed oxidation-mass spectrometry results. The deployment of the [P-4,P-4,P-4,P-2][ DEP] and tributylmethylphosphonium methylsulfate Its as additives also show good inhibitory effect on coal oxidation over the temperature range studied, and a relatively stronger interaction between [P-4,P-4,P-4,P-2] [DEP] and coal is demonstrated by the additive model.

A proposed model membrane and test method for microneedle insertion studies

A commercial polymeric film (Parafilm M (R), a blend of a hydrocarbon wax and a polyolefin) was evaluated as a model membrane for microneedle (MN) insertion studies. Polymeric MN arrays were inserted into Parafilm M (R) (PF) and also into excised neonatal porcine skin. Parafilm M (R) was folded before the insertions to closely approximate thickness of the excised skin. Insertion depths were evaluated using optical coherence tomography (OCT) using either a force applied by a Texture Analyser or by a group of human volunteers. The obtained insertion depths were, in general, slightly lower, especially for higher forces, for PF than for skin. However, this difference was not a large, being less than the 10% of the needle length. Therefore, all these data indicate that this model membrane could be a good alternative to biological tissue for MN insertion studies. As an alternative method to OCT, light microscopy was used to evaluate the insertion depths of MN in the model membrane. This provided a rapid, simple method to compare different MN formulations. The use of Parafilm M (R), in conjunction with a standardised force/time profile applied by a Texture Analyser, could provide the basis for a rapid MN quality control test suitable for in-process use. It could also be used as a comparative test of insertion efficiency between candidate MN formulations.