Process and catalysts for the methanation of oxides of carbon

The present invention is directed to catalysts for the conversion of oxides of carbon to methane and/or other hydrocarbons and to precursors of such catalysts. The catalyst precursors include one or more refractory oxides selected from the group consisting of rare earth oxides and rare earth contg. perovskites, the precursor including nickel or nickel cations sufficient for a catalyst obtainable by reducing the precursor to be capable of at least partially reducing an oxide of carbon to a hydrocarbon product. Processes for the prepn. of such catalysts and catalyst precursors are also disclosed, as are processes for the conversion of oxides of carbon to methane and/or other hydrocarbons. [on SciFinder(R)]

Perdido : the first Smart Field in the western hemisphere

Located in the Gulf of Mexico in nearly 8,000 feet of water, the Perdido development is the world’s deepest spar and Shell’s first Smart Field in the Western hemisphere. Jointly developed by Shell, BP, and Chevron, the spar and the subsea equipment connected to it will eventually capture approximately an order of magnitude more data than is collected from any other Shell-designed and managed development currently operating in the Gulf of Mexico. This paper will describe Shell’s Smart Fields design philosophy, briefly explain the five design elements that underpin “smartness” in Shell’s North and South American operations—specifically, remote assisted operations, exception-based surveillance, collaborative work environments, hydrocarbon development tools and workflows, and Smart Fields Foundation IT infrastructure—and shed light on the process by which a highly customized Smart Fields development and management plan was put together for Perdido.

Phenytoin metabolism by human cytochrome P450 : involvement of P450 3A and 2C forms in secondary metabolism and drug-protein adduct formation

The anticonvulsant phenytoin (5,5-diphenylhydantoin) provokes a skin rash in 5 to 10% of patients, which heralds the start of an idiosyncratic reaction that may result from covalent modification of normal self proteins by reactive drug metabolites. Phenytoin is metabolized by cytochrome P450 (P450) enzymes primarily to 5-(p-hydroxyphenyl-),5-phenylhydantoin (HPPH), which may be further metabolized to a catechol that spontaneously oxidizes to semiquinone and quinone species that covalently modify proteins. The aim of this study was to determine which P450s catalyze HPPH metabolism to the catechol, proposed to be the final enzymatic step in phenytoin bioactivation. Recombinant human P450s were coexpressed with NADPH-cytochrome P450 reductase in Escherichia coli. Novel bicistronic expression vectors were constructed for P450 2C19 and the three major variants of P450 2C9, i.e., 2C9*1, 2C9*2, and 2C9*3. HPPH metabolism and covalent adduct formation were assessed in parallel. P450 2C19 was the most effective catalyst of HPPH oxidation to the catechol metabolite and was also associated with the highest levels of covalent adduct formation. P450 3A4, 3A5, 3A7, 2C9*1, and 2C9*2 also catalyzed bioactivation of HPPH, but to a lesser extent. Fluorographic analysis showed that the major targets of adduct formation in bacterial membranes were the catalytic P450 forms, as suggested from experiments with human liver microsomes. These results suggest that P450 2C19 and other forms from the 2C and 3A subfamilies may be targets as well as catalysts of drug-protein adduct formation from phenytoin.

Surface functionalization on the thermal conductivity of graphene–polymer nanocomposites

Exploring thermal transport in graphene-polymer nanocomposite is significant to its applications with better thermal properties. Interfacial thermal conductance between graphene and polymer matrix plays a critical role in the improvement of thermal conductivity of graphene-polymer nanocomposite. Unfortunately, it is still challenging to understand the interfacial thermal transport between graphene nanofiller and polymer matrix at small material length scale. To this end, using non-equilibrium molecular dynamics simulations, we investigate the interfacial thermal conductance of graphene-polyethylene (PE) nanocomposite. The influence of functionalization with hydrocarbon chains on the interfacial thermal conductance of graphene-polymer nanocomposites was studied, taking into account of the effects of model size and thermal conductivity of graphene. An analytical model is also used to calculate the thermal conductivity of nanocomposite. The results are considered to contribute to development of new graphene-polymer nanocomposites with tailored thermal properties.

The identification and rapid extraction of hydrocarbons from Nicotiana glauca : A potential advanced renewable biofuel source

Declining fossil fuels reserves, a need for increased energy security and concerns over carbon emissions from fossil fuel use are the global drivers for alternative, renewable, biosources of fuels and chemicals. In the present study the identification of long chain (C29–C33) saturated hydrocarbons from Nicotiana glauca leaves is reported. The occurrence of these hydrocarbons was detected by gas chromatography–mass spectrometry (GC–MS) and identification confirmed by comparison of physico-chemical properties displayed by the authentic standards available. A simple, robust procedure was developed to enable the generation of an extract containing a high percentage of hydrocarbons (6.3% by weight of dried leaf material) higher than previous reports in other higher plant species consequently, it is concluded that N. glauca could be a crop of greater importance than previously recognised for biofuel production. The plant can be grown on marginal lands, negating the need to compete with food crops or farmland, and the hydrocarbon extract can be produced in a non-invasive manner, leaving remaining biomass intact for bioethanol production and the generation of valuable co-products.

Construction of interstellar cumulenes and heterocumulenes : Mass spectrometric studies

The last few years have brought an increasing interest in the chemistry of rite interstellar and circumstellar environs. Many of the molecular species discovered in remote galactic regions have been dubbed 'non-terrestrial' because of their unique structures (Thaddeus et al, 1993). These findings have provided a challenge to chemists in many differing fields to attempt to generate these unusual species in the laboratory of particular recent interest have been the unsaturated hydrocarbon families, CnH and CnH2, which have been pursued by a number of diverse methodologies. A wine range of heterocumulenes, including CnO, HCnO, CnN, HCnN, CnS, HCnS, CnSi and HCnSi have also provided intriguing targets for laboratory experiments. Strictly the term cumulene refers to a class of compounds that possess a series of adjacent double bonds, with allene representing the simplest example (H2C=C=CH2). However for many of the non-terrestrial molecules presented here, the carbon chain cannot be described in terms of a single simple valence structure, and so we use the terms cumulene and heterocumulene in a more general sense: to describe molecular species that contain an unsaturated polycarbon chain. Mass spectrometry has proved an invaluable tool in the quest for interstellar cumulenes and heterocumulenes in the laboratory it has the ability in its many forms, to (i) generate charged analogs of these species in the gas phase, (ii) probe their connectivity, ion chemistry, and thermochemistry, and (iii) in some cases, elucidate the neutrals themselves. Here, we will discuss the progress of these studies to this time. (C) 1999 John Wiley & Sons, Inc.

Transcript and metabolite profiling for the evaluation of tobacco tree and poplar as feedstock for the bio-based industry

The global demand for food, feed, energy and water poses extraordinary challenges for future generations. It is evident that robust platforms for the exploration of renewable resources are necessary to overcome these challenges. Within the multinational framework MultiBioPro we are developing biorefinery pipelines to maximize the use of plant biomass. More specifically, we use poplar and tobacco tree (Nicotiana glauca) as target crop species for improving saccharification, isoprenoid, long chain hydrocarbon contents, fiber quality, and suberin and lignin contents. The methods used to obtain these outputs include GC-MS, LC-MS and RNA sequencing platforms. The metabolite pipelines are well established tools to generate these types of data, but also have the limitations in that only well characterized metabolites can be used. The deep sequencing will allow us to include all transcripts present during the developmental stages of the tobacco tree leaf, but has to be mapped back to the sequence of Nicotiana tabacum. With these set-ups, we aim at a basic understanding for underlying processes and at establishing an industrial framework to exploit the outcomes. In a more long term perspective, we believe that data generated here will provide means for a sustainable biorefinery process using poplar and tobacco tree as raw material. To date the basal level of metabolites in the samples have been analyzed and the protocols utilized are provided in this article.

Vertical graphene gas- and bio-sensors via catalyst-free, reactive plasma reforming of natural honey

A rapid reforming of natural honey exposed to reactive low-temperature Ar + H2 plasmas produced high-quality, ultra-thin vertical graphenes, without any metal catalyst or external heating. This transformation is only possible in the plasma and fails in similar thermal processes. The process is energy-efficient, environmentally benign, and is much cheaper than common synthesis methods based on purified hydrocarbon precursors. The graphenes retain the essential minerals of natural honey, feature reactive open edges and reliable gas- and bio-sensing performance.

Real-time monitoring of nucleation-growth cycle of carbon nanoparticles in acetylene plasmas

Quantum cascade laserabsorption spectroscopy was used to measure the absolute concentration of acetylene in situ during the nanoparticle growth in Ar + C2H2 RF plasmas. It is demonstrated that the nanoparticle growth exhibits a periodical behavior, with the growth cycle period strongly dependent on the initial acetylene concentration in the chamber. Being 300 s at 7.5% of acetylene in the gas mixture, the growth cycle period decreases with the acetylene concentration increasing; the growth eventually disappears when the acetylene concentration exceeds 32%. During the nanoparticle growth, the acetylene concentration is small and does not exceed 4.2% at radio frequency (RF) power of 4 W, and 0.5% at RF power of 20 W. An injection of a single acetylene pulse into the discharge also results in the nanoparticlenucleation and growth. The absorption spectroscopy technique was found to be very effective for the time-resolved measurement of the hydrocarbon content in nanoparticle-generatingplasmas.

Ion-assisted precursor dissociation and surface diffusion : enabling rapid, low-temperature growth of carbon nanofibers

Growth kinetics of carbon nanofibers in a hydrocarbon plasma is studied. In addition to gas-phase and surface processes common to chemical vapor deposition, the model includes (unique to plasma-exposed catalyst surfaces) ion-induced dissociation of hydrocarbons, interaction of adsorbed species with incoming hydrogen atoms, and dissociation of hydrocarbon ions. It is shown that at low, nanodevice-friendly process temperatures the nanofibers grow via surface diffusion of carbon adatoms produced on the catalyst particle via ion-induced dissociation of a hydrocarbon precursor. These results explain a lower activation energy of nanofiber growth in a plasma and can be used for the synthesis of other nanoassemblies. © 2007 American Institute of Physics.

Hydrogen in plasma-nanofabrication : selective control of nanostructure heating and passivation

The possibility of independent control of the surface fluxes of energy and hydrogen-containing radicals, thus enabling selective control of the nanostructure heating and passivation, is demonstrated. In situ energy flux measurements reveal that even a small addition of H2 to low-pressure Ar plasmas leads to a dramatic increase in the energy deposition through H recombination on the surface. The heat release is quenched by a sequential addition of a hydrocarbon precursor while the surface passivation remains effective. Such selective control offers an effective mechanism for deterministic control of the growth shape, crystallinity, and density of nanostructures in plasma-aided nanofabrication. © 2010 American Institute of Physics.

Low- and high-temperature controls in carbon nanofiber growth in reactive plasmas

A numerical growth model is used to describe the catalyzed growth of carbon nanofibers in the sheath of a low-temperature plasma. Using the model, the effects of variation in the plasma sheath parameters and substrate potential on the carbon nanofiber growth characteristics, such as the growth rate, the effective carbon flux to the catalyst surface, and surface coverages, have been investigated. It is shown that variations in the parameters, which change the sheath width, mainly affect the growth parameters at the low catalyst temperatures, whereas the other parameters such as the gas pressure, ion temperature, and percentages of the hydrocarbon and etching gases, strongly affect the carbon nanofiber growth at higher temperatures. The conditions under which the carbon nanofiber growth can still proceed under low nanodevice-friendly process temperatures have been formulated and summarized. These results are consistent with the available experimental results and can also be used for catalyzed growth of other high-aspect-ratio nanostructures in low-temperature plasmas.

Performance and gaseous and particle emissions from a liquefied petroleum gas (LPG) fumigated compression ignition engine

In this study, an LPG fumigation system was fitted to a Euro III compression ignition (CI) engine to explore its impact on performance, and gaseous and particulate emissions. LPG was introduced to the intake air stream (as a secondary fuel) by using a low pressure fuel injector situated upstream of the turbocharger. LPG substitutions were test mode dependent, but varied in the range of 14-29% by energy. The engine was tested over a 5 point test cycle using ultra low sulphur diesel (ULSD), and a low and high LPG substitution at each test mode. The results show that LPG fumigation coerces the combustion into pre-mixed mode, as increases in the peak combustion pressure (and the rate of pressure rise) were observed in most tests. The emissions results show decreases in nitric oxide (NO) and particulate matter (PM2.5) emissions; however, very significant increases in carbon monoxide (CO) and hydrocarbon (HC) emissions were observed. A more detailed investigation of the particulate emissions showed that the number of particles emitted was reduced with LPG fumigation at all test settings – apart from mode 6 of the ECE R49 test cycle. Furthermore, the particles emitted generally had a slightly larger median diameter with LPG fumigation, and had a smaller semi-volatile fraction relative to ULSD. Overall, the results show that with some modifications, LPG fumigation systems could be used to extend ULSD supplies without adversely impacting on engine performance and emissions.

Effects of ions and atomic hydrogen in plasma-assisted growth of single-walled carbon nanotubes

The growth of single-walled carbon nanotubes (SWCNTs) in plasma-enhanced chemical vapor deposition (PECVD) is studied using a surface diffusion model. It is shown that at low substrate temperatures (≤1000 K), the atomic hydrogen and ion fluxes from the plasma can strongly affect nanotube growth. The ion-induced hydrocarbon dissociation can be the main process that supplies carbon atoms for SWCNT growth and is responsible for the frequently reported higher (compared to thermal chemical vapor deposition) nanotube growth rates in plasma-based processes. On the other hand, excessive deposition of plasma ions and atomic hydrogen can reduce the diffusion length of the carbon-bearing species and their residence time on the nanotube lateral surfaces. This reduction can adversely affect the nanotube growth rates. The results here are in good agreement with the available experimental data and can be used for optimizing SWCNT growth in PECVD.

Microscopic ion fluxes in plasma-aided nanofabrication of ordered carbon nanotip structures

Three-dimensional topography of microscopic ion fluxes in the reactive hydrocarbon-based plasma-aided nanofabrication of ordered arrays of vertically aligned single-crystalline carbon nanotip microemitter structures is simulated by using a Monte Carlo technique. The individual ion trajectories are computed by integrating the ion equations of motion in the electrostatic field created by a biased nanostructured substrate. It is shown that the ion flux focusing onto carbon nanotips is more efficient under the conditions of low potential drop Us across the near-substrate plasma sheath. Under low- Us conditions, the ion current density onto the surface of individual nanotips is higher for higher-aspect-ratio nanotips and can exceed the mean ion current density onto the entire nanopattern in up to approximately five times. This effect becomes less pronounced with increasing the substrate bias, with the mean relative enhancement of the ion current density ξi not exceeding ∼1.7. The value of ξi is higher in denser plasmas and behaves differently with the electron temperature Te depending on the substrate bias. When the substrate bias is low, ξi decreases with Te, with the opposite tendency under higher- Us conditions. The results are relevant to the plasma-enhanced chemical-vapor deposition of ordered large-area nanopatterns of vertically aligned carbon nanotips, nanofibers, and nanopyramidal microemitter structures for flat-panel display applications. © 2005 American Institute of Physics.