Transformation Of Hydrocarbons Research Articles

Molecular mechanism of formation of supported platinum catalysts of the Pt/Al2O3 family

Certain stages of the classical procedure for preparing aluminum-platinum catalysts, whose understanding is important from both the basic and practical viewpoints, are considered on the molecular level. Properties of both participants (active component precursor solution and oxide surface) are shown to be inhomogeneous, which can affect interaction of the components at the fixing stage. Existing views (and their evolution) on the mechanism of adsorption of platinum complexes from aqueous solutions on aluminum oxide surface are discussed. The role of chemical processes on the stage of fixing precursor on the electronic and structural properties of the supported metal is demonstrates. Strong metal-support interaction is shown to endow platinum with specific adsorption and catalytic properties in hydrocarbon transformation reactions.

Methoxychlor Suppresses the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible CYP1A1 Expression in Murine Hepa-1c1c7 Cells

Methoxychlor (MXC) is a pesticide that was developed as a replacement for dichlorodiphenyltrichloroethane (DDT). The influence of MXC on CYP1A1 expression or the functions of mouse hepatoma Hepa-1clc7 remain unclear. Cultured Hepa-1c1c7 cells were treated with MXC with or without 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to assess the role of MXC on CYP1A1 expression. MXC alone did not affect CYP1A1-specific 7-ethoxyresorufin O-deethylase (EROD) activity. In contrast, TCDD-inducible EROD activities were markedly reduced upon concomitant treatment with TCDD and MXC in a concentration-dependent manner. Treatment with ICI 182.780, an estrogen-receptor antagonist, did not affect the suppressive effects of MXC on TCDD-inducible EROD activity. TCDD-inducible CYP1A1 mRNA levels were markedly suppressed upon treatment with TCDD and MXC, and this is consistent with their effects on EROD activity. A transient transfection assay using dioxin-response element (DRE)-linked luciferase and an electrophoretic mobility shift assay revealed that MXC reduced the transformation of the aryl hydrocarbons (Ah) receptor to a form capable of specifically binding to the DRE sequence in the promoter region of the CYP1A1 gene. These results suggest that the downregulation of CYP1A1 gene expression by MXC in Hepa-1c1c7 cells might be an antagonism of the DRE binding potential of the nuclear Ah receptor but is not mediated through the estradiol receptor.

Transformation of Polycyclic Aromatic Hydrocarbons by Laccase Is Strongly Enhanced by Phenolic Compounds Present in Soil

Efficient transformation of several polycyclic aromatic hydrocarbons (PAHs) was obtained using a fungal laccase in the presence of phenolic compounds related to those formed in nature during the turnover of lignin and humus. The effect of these natural mediators, namely vanillin, acetovanillone, acetosyringone, syringaldehyde, 2,4,6-trimethylphenol, p-coumaric acid, ferulic acid, and sinapic acid, was compared with that of synthetic mediators such as 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and 1-hydroxybenzotriazole (HBT). Anthracene was significantly degraded by laccase in the absence of mediators, whereas benzo[a]pyrene and pyrene were weakly transformed (less than 15% after 24 h). Vanillin, acetovanillone, 2,4,6-trimethylphenol, and, above all, p-coumaric acid strongly promoted the removal of PAHs by laccase. 9,10-Anthraquinone was the main product detected from anthracene oxidation by all the laccase-mediator systems. The yield of anthraquinone formed was directly correlated with the amount of p-coumaric acid used. This compound resulted in a better laccase mediator than ABTS and close similarity to HBT, attaining 95% removal of anthracene and benzo[a]pyrene and around 50% of pyrene within 24 h. Benzo[a]pyrene 1,6-, 3,6-, and 6,12-quinones were produced during benzo[a]pyrene oxidation with laccase and p-coumaric acid, HBT, or ABTS as mediators, although use of the latter mediator gave further oxidation products that were not produced by the two other systems.

Transformations of oil cut hydrocarbons in catalytic modification with α-olefins

The change in the structural and group composition of paraffins and naphthenes and aromatics in the oil cut before and after alkylation with a-olefins was investigated. Oligoalkylation of these hydrocarbons and rupture of naphthene rings in hybrid structures and isomerization of alkyl fragments are reflected in the quality of the products obtained.

Novel palladium acetate based protocols for transformations of unsaturated hydrocarbons

Catalyst systems based on palaadium carboxylates and boron trifluoride etherate were examined in the dimerization of styrene, telomerization of butadiene with diethylamine and homopolymerization of norbornene. The systems are shown to have higher efficiency than their palladium β-diketonate prototypes at analogous conditions.

Energy: The Next Biotechnology Challenge

Technology Tomorrow - This is the second-to-last installment in this yearlong series examining R&D needs and potential. This article explores the challenges of applying biotechnology to the oil and gas sector and hints at the possibility of genetically modified organisms to achieve superior results. The current scientific uncertainty on just how future organisms will be included in the global energy picture suggests full speed ahead on the science, with the understanding that the issue of industry acceptance will need to be properly evaluated and managed. The Technology Tomorrow Series, comprising articles published in JPT during 2006 and 2007, is available as a collection on OnePetro (SPE-160929-JPT). Editor's note: This is the second-to-last installment in this yearlong series examining R&D needs and potential. This article explores the challenges of applying biotechnology to the oil and gas sector and hints at the possibility of genetically modified organisms to achieve superior results. The current scientific uncertainty on just how future organisms will be included in the global energy picture suggests full speed ahead on the science, with the understanding that the issue of industry acceptance will need to be properly evaluated and managed. The Technology Tomorrow Series, comprising articles published in JPT during 2006 and 2007, is available as a collection on OnePetro (SPE-160929-JPT). Today the impact of biotechnology is most noticeable in the health and pharmaceutical sectors, chemical industry, and in environmental technologies. The time is coming when it also will play a role in the energy sector. This is the result of progress in two major areas that are likely to have important consequences. The first one is the growing awareness of the major chemical fluxes fueled in the depths of the Earth's crust by the deep biosphere: microorganisms that live without oxygen and form the basis of previously unrecognized element cycles completely different from those that take place at the surface, driven by solar energy and oxygen. The simultaneous presence of minerals, gases, hydrocarbons, and bacteria in the anoxic deep biosphere is the basis of new speculation on carbon cycling in anoxic regions. Microbiologists now have new tools to detect and monitor biological activity in the environment, among which are the powerful techniques of specific DNA amplification and detection, which are best known to nonexperts for their applications in crime forensics. In just about the same way, specific types of bacteria can be detected in minimal amounts from any type of environment and recognized and functionally identified—for example, sulfate recycling bacteria (associated with the souring of reservoirs and oil-extraction systems) living at extraordinary depths and temperatures. The second major field of influence will be biological fuel synthesis and carbon capture from renewables. Interest in these possibilities blossomed and waned in the 1970s, but the area is now experiencing renewed interest, funding, and revival by the exploitation of fast-progressing genomics and bioengineering techniques. This article addresses the relevance and potential of biotechnology applications to the energy industry, envisioning the areas where biotechnology science progress might affect present and future business. Black Energy: Oil, Gas, and Bugs Oil and gas have been part of this planet for so long that the smallest living cells on the surface and in the deep biosphere have evolved ways to feed on them and gain energy, however unpalatable the ingredients might be. Bacterial degradation of crude oil in the reservoir is the cause of the poor quality of oil found in many areas, from the Canadian tar sands to offshore fields. Some of the biochemical pathways of oil hydrocarbon transformation are known, but many remain to be clarified, including mechanisms that might be in action in the reservoirs where temperature is compatible with bacterial life. Recent indications support the possibility of in-situ bioconversion processes of oil to methane and maybe even to other gaseous hydrocarbons. In similar ways to biological conversion of some types of coal to methane, exploitation and acceleration of the natural phenomena could be an interesting alternative to other traditional technologies of energy recovery from difficult sources.

Anaerobic Cometabolic Transformation of Polycyclic and Heterocyclic Aromatic Hydrocarbons: Evidence from Laboratory and Field Studies

The sulfate-reducing enrichment culture N47 can grow on naphthalene or 2-methylnaphthalene as the sole carbon and energy source. Here we show that the culture can furthermore cometabolicallytransform a variety of polycyclic and heteroaromatic compounds with naphthalene or methylnaphthalene as the auxiliary substrate. Most of the cosubstrates were converted to the corresponding carboxylic acids, frequently to several isomers. The mass spectra of specific metabolites that were extracted from supernatants of cultures containing the cosubstrates benzothiophene, benzofuran, and 1-methylnaphthalene resembled known intermediates of the anaerobic naphthalene and 2-methylnaphthalene degradation pathways (i.e., naphthyl-2-methylsuccinic acid and naphthyl-2-methylenesuccinic acid). This indicates that some of the tested compounds were first methylated and then transformed to the corresponding methylsuccinic acids by a fumarate addition to the methyl group. For some of the cosubstrates, a partial or total inhibition of growth on the auxiliary substrate was observed. This was not caused by the toxicity of the individual cosubstrate itself, but by a specific combination of auxiliary substrate and cosubstrate. None of the cosubstrates tested could be utilized as the sole carbon source and electron donor by the enrichment culture N47. Field investigations at the tar-oil-contaminated aquifer, where strain N47 originated, revealed the presence of a number of metabolites similar to the ones identified in batch culture supernatants. Our findings suggest that aromatic hydrocarbons and heterocyclic compounds can be converted by aquifer organisms and produce a variety of polar compounds that become mobile in groundwater.

Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City

Abstract. Understanding sources, concentrations, and transformations of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere is important because of their potent mutagenicity and carcinogenicity. The measurement of particle-bound PAHs by three different methods during the Mexico City Metropolitan Area field campaign in April 2003 presents a unique opportunity for characterization of these compounds and intercomparison of the methods. The three methods are (1) collection and analysis of bulk samples for time-integrated gas- and particle-phase speciation by gas chromatography/mass spectrometry; (2) aerosol photoionization for fast detection of PAHs on particles' surfaces; and (3) aerosol mass spectrometry for fast analysis of size and chemical composition. This research represents the first time aerosol mass spectrometry has been used to measure ambient PAH concentrations and the first time that fast, real-time methods have been used to quantify PAHs alongside traditional filter-based measurements in an extended field campaign. Speciated PAH measurements suggest that motor vehicles and garbage and wood burning are important sources in Mexico City. The diurnal concentration patterns captured by aerosol photoionization and aerosol mass spectrometry are generally consistent. Ambient concentrations of particle-phase PAHs typically peak at ~110 ng m-3 during the morning rush hour and rapidly decay due to changes in source activity patterns and dilution as the boundary layer rises, although surface-bound PAH concentrations decay faster. The more rapid decrease in surface versus bulk PAH concentrations during the late morning suggests that freshly emitted combustion-related particles are quickly coated by secondary aerosol material in Mexico City's atmosphere and may also be transformed by heterogeneous reactions.

Nanosized carbon forms in the processes of pressure–temperature-induced transformations of hydrocarbons

The products of thermal conversions of naphthalene, anthracene, pentacene, perylene, and coronene at 8 GPa in the temperature range up to 1300 °C have been studied by scanning electron and high-resolution transmission electron microscopies. As a result, it has been established that various nanometer-sized carbon species (spherical and coalesced two-core onion-like carbon particles, faceted polyhedral particles, graphitic ribbons, graphitic folds, and nanocrystalline diamonds) are present in the conversion products together with micron-sized crystallites of graphite and diamond.

Characterization and catalytic study of Pt [sbnd]Ge/Al 2O 3 catalysts prepared by organometallic grafting

Ge was added to 1% Pt/Al 2O 3 catalyst by controlled surface reaction of Ge( n-C 4H 9) 4 in amounts corresponding nominally to 1/12, 1/8, 1/2, 1, or 2 monolayers. These Pt Ge/Al 2O 3 catalysts were characterized by FTIR of CO, TEM, H 2 chemisorption, and EXAFS as well as tested in catalytic reactions, that is, transformation of hexane, benzene and cyclohexene in the presence of excess hydrogen. Loading of Ge in amounts of 1/12–1/2 monolayers resulted in catalysts with “bimetallic surface.” Loading of 1/12 monolayer of Ge resulted in randomly deposited Ge atoms on the surface of Pt. It hardly affected the catalytic behavior as compared with the Ge-free parent catalyst; 1/8 monolayer of Ge was still located on Pt as single atoms (as shown by EXAFS), but Ge selectively poisoned high coordination sites, active in benzene hydrogenation. This reaction was completely suppressed here, whereas this catalyst was most active in cyclohexene transformation. Pt with 1/8 and 1/2 monolayers of Ge transformed hexane with high selectivity into saturated C 6 products and formed hardly any benzene. The formation of cyclohexane from hexane was also observed, not typical for monofunctional Pt catalysts. Adding 1–2 monolayers of Ge caused a new type of interaction between Pt and Ge containing sites that adsorbed CO but did not adsorb hydrogen. A solid solution of Pt Ge may have arisen here, creating “bulk bimetallic catalysts” with somewhat more surface Pt atoms not interacting with Ge. These catalysts behaved similarly in hydrocarbon transformations as the original parent catalyst. The possible reaction mechanism of hexane transformation is discussed in detail, in terms of thermodynamic limitations of benzene formation and possible surface species.

Analysis of Conditions of Petroleum Hydrocarbon Transformations in Seawater and Simulation of This Process in Aniva Bay

Simulation methods are used to study the self-purification capacity of water from Aniva Bay before the construction on the coast of the bay of the world's largest liquefied natural gas plant and oil loading terminals for ships with a displacement of 100 000 t or more. The calculations are made by using a hydro-ecological model and long-term data on Aniva Bay oceanography. Its water area was divided into five areas, and for these areas, we determined the hydrological and hydrochemical characteristics, evaluated fluxes through their boundaries, estimated petroleum hydrocarbon (PHC) loads, and calculated the annual dynamics of their concentrations and the biomasses of oil-oxidizing bacteria. PHC balances for the five water areas and Aniva Bay as a whole were calculated. PHC consumption by oil-oxidizing bacteria is the most important process of PHC transformation. The discrepancy of the estimated PHC balance in Aniva Bay was found to equal 2.61%, which is within the calculation accuracy.

X-ray study of the native solid hydrocarbons transformation

X-ray study of the native solid hydrocarbons transformation

Heats of Adsorption of Ammonia and Correlation of Activity and Acidity in Heterogeneous Catalysis

Adsorption microcalorimetry was applied to determine heats of adsorption of ammonia on zeolites Y, mordenite, ZSM-5, heteropolyacid H3PW12O40, as well as silica gel and amorphous aluminosilicates. The plots of differential heats against coverage served to construct the acidity spectra and, in this way, to determine the number of acid sites with different acidity strengths. The behavior of these materials in acid-catalyzed reactions, primarily, in the transformations of hydrocarbons is discussed. Evidence is presented that heats of adsorption of ammonia can be used to obtain correlation plots that describe relations between acidic and catalytic properties of zeolite catalysts.

Aromatic and aliphatic hydrocarbon consumption and transformation by the styrene degrading strain Pseudomonas putida CA-3

Pseudomonas putida CA-3 is capable of consuming a number of aromatic and aliphatic hydrocarbons. With the exception of styrene none of the alkenes tested are capable of supporting the growth of P. putida CA-3 as sole sources of carbon and energy. The highest rate of alkene consumption was observed with styrene as the substrate. A 6.5- and 15.5-fold lower rate of substrate consumption was observed with indene and indole with the concomitant formation of 2-indanone and indigo, respectively. The presence of a sulphur (benzothiopene) or oxygen (benzofuran) in the cyclopentene ring resulted in further decreases in the rate of substrate consumption by whole cells of P. putida CA-3. P. putida CA-3 is incapable of consuming benzene and consumes toluene at a low rate. No detectable products were observed in supernatants of cultures incubated with benzothiopene, benzofuran or toluene. The aliphatic alkenes 1-octene and 1,7-octadiene were both consumed by whole cells of P. putida CA-3 at a rate equivalent to indene consumption. The consumption of ( R) styrene oxide was 1.7- and 1.25-fold higher than that of the S isomer and the racemic mix, respectively. The rate of racemic indene oxide, 1,2-epoxyoctane and 1,2-epoxy-7-octene consumption was lower than their equivalent alkene and 55-, 11.8-, and 27.5-fold lower than the rate of racemic styrene oxide consumption. A transposon mutant incapable of growth with styrene or styrene oxide failed to transform indole to indigo. The ratio of styrene utilisation relative to other substrates changes in the mutant strain compared to the wild-type strain, e.g., Indene biotransformation by mutant AF5 is 1.9-fold higher than styrene consumption compared to the wild-type strain CA-3 where the rate of styrene consumption is 6.7-fold higher than indene consumption. This trend is also observed for other alkenes and epoxides.

Stabilities of C 3–C 5 alkoxide species inside H-FER zeolite: a hybrid QM/MM study

Adsorption ( π-complex formation) and chemisorption (alkoxide formation) of ethene, propene, 1-butene, and 1-pentene, as well as of isobutene and 2-methyl-1-butene, in zeolite H-FER are examined by a hybrid quantum mechanics/molecular mechanics (QM/MM) method that takes van der Waals (dispersion) interactions into account. The predicted heats of adsorption (36, 51, 45, 64, 41, 47 kJ/mol, respectively) fall into energy ranges inferred from experimental values for alkanes in H-zeolites. Vibrational frequencies are calculated for adsorbed butenes and butyl alkoxide species and compared with observed spectra for adsorbed 1-butene and isobutene. Primary and secondary alkoxide species are found to be significantly more stable than the adsorption complexes with chemisorption energies between 137 and 205 kJ/mol. The stability increases with the length of the alkyl chain. Geometrical constrictions close to the active site result in reduced stabilities of bulky alkoxide isomers. The tert-butyl and 1,1-dimethylpropyl species are less stable (chemisorption energies of 62 and 78 kJ/mol, respectively) or even nonexistent at sterically hindered framework positions. The implications of relatively stable alkoxide intermediates for hydrocarbon transformation reactions over H-zeolites are discussed.

Carbon accumulation, deactivation and reactivation of Pt catalysts upon exposure to hydrocarbons

The formation and catalytic effect of carbonaceous deposits was studied on monofunctional Pt catalysts: Pt black (PtN, i.e., reduced with hydrazine), Pt/SiO 2 (EUROPT-1), Pt on “herringbone” graphite nanofiber (Pt/GNF-H, GNF being able to store hydrogen) and Pt/CeO 2 (ceria tending to consume spilt over hydrogen). They were exposed to hexane or t,t-hexa-2,4-diene between 483 and 663 K, with or without H 2. Hydrocarbon transformations during these deactivating exposures as well as in subsequent standard test reaction with hexane in hydrogen excess were studied. Carbon accumulation on Pt black after analogous deactivating treatments was also examined by electron spectroscopy (XPS and UPS). The abundance of hydrogen on Pt sites controlled the activity and selectivity containing much Pt C species. The amount of surface C could reach ∼45% causing almost total activity loss, but even ∼30% C on Pt blacks decreased markedly the catalytic activity, due to massive 3D deposits. “Disordered” carbon selectively poisoned the formation of saturated C 6 products and fragmentation. The yield of dehydrogenation to hexenes was a good universal indicator of deactivation for each catalyst. Four regions were distinguished: “beneficial”, “selective”, “non-selective” and “severe” deactivation.

Strategies for targeting marker bacterial oxygenases involved in transformation of hydrocarbons in contaminated soil

A variety of activities leads to release of petroleum products in soil. In this study, DNA extracted from oil and grease contaminated soil by a simple technique was used as a template for Polymerase Chain Reaction based assays. Target gene sequences of certain key bacterial oxygenases involved in transformation of aromatic hydrocarbons viz. naphthalene dioxygenase, catechol 2,3‐dioxygenase, cytochrome P‐450cam monooxygenase as well as eubacterial 16S rRNA gene, were evaluated for determining the presence of microbial genotypes in soil. It was concluded that duplex, nested and multiplex PCR assay strategies in combination with residue analysis can play a crucial role in the selection of treatment processes as well as monitoring the efficacy of bioremedial technique.

Fungal Transformation of Monoterpenes

Fungal transformation of monoterpenes was less frequently studied compared to other natural products until a few decades ago due to their toxicity, volatility and general difficulty in handling. In recent years, however, researchers have paid much attention and reported the fungal transformation of acyclic, monocyclic and bicyclic monoterpene hydrocarbons, and oxygenated monoterpenes and their derivatives. The present review thus summarizes the fungal transformation of acyclic, mono- and bicyclic monoterpene hydrocarbons, oxygenated monoterpenes and their derivatives. The bacterial transformations are not included in the present review. Keywords: Fungal transformation, monoterpenes, oxygenated monoterpenes, hydrocarbons

Black tea extract suppresses transformation of aryl hydrocarbon receptor induced by dioxin

Dioxins cause various adverse effects through binding to an aryl hydrocarbon receptor (AhR) and transformation of the receptor. In this study, we investigated whether black tea extract suppresses AhR transformation. Dried black tea leaves were extracted with 75% ethanol, and the extract was pretreated to the rat liver cytosol fraction 10 min prior to addition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Transformed AhR was detected by electrophoretic gel mobility shift assay. Black tea extract suppressed AhR transformation in a dose-dependent manner, and the IC50 value against 1 nM TCDD-induced AhR transformation was 8.9 microg/ml. The result suggests that intake of black tea has a potential to suppress the AhR transformation, leading protection from dioxin toxicity.

Recent advances in petroleum microbiology.

Recent advances in molecular biology have extended our understanding of the metabolic processes related to microbial transformation of petroleum hydrocarbons. The physiological responses of microorganisms to the presence of hydrocarbons, including cell surface alterations and adaptive mechanisms for uptake and efflux of these substrates, have been characterized. New molecular techniques have enhanced our ability to investigate the dynamics of microbial communities in petroleum-impacted ecosystems. By establishing conditions which maximize rates and extents of microbial growth, hydrocarbon access, and transformation, highly accelerated and bioreactor-based petroleum waste degradation processes have been implemented. Biofilters capable of removing and biodegrading volatile petroleum contaminants in air streams with short substrate-microbe contact times (<60 s) are being used effectively. Microbes are being injected into partially spent petroleum reservoirs to enhance oil recovery. However, these microbial processes have not exhibited consistent and effective performance, primarily because of our inability to control conditions in the subsurface environment. Microbes may be exploited to break stable oilfield emulsions to produce pipeline quality oil. There is interest in replacing physical oil desulfurization processes with biodesulfurization methods through promotion of selective sulfur removal without degradation of associated carbon moieties. However, since microbes require an environment containing some water, a two-phase oil-water system must be established to optimize contact between the microbes and the hydrocarbon, and such an emulsion is not easily created with viscous crude oil. This challenge may be circumvented by application of the technology to more refined gasoline and diesel substrates, where aqueous-hydrocarbon emulsions are more easily generated. Molecular approaches are being used to broaden the substrate specificity and increase the rates and extents of desulfurization. Bacterial processes are being commercialized for removal of H(2)S and sulfoxides from petrochemical waste streams. Microbes also have potential for use in removal of nitrogen from crude oil leading to reduced nitric oxide emissions provided that technical problems similar to those experienced in biodesulfurization can be solved. Enzymes are being exploited to produce added-value products from petroleum substrates, and bacterial biosensors are being used to analyze petroleum-contaminated environments.