We developed methods and technology to identify oil and gas fields that are likely to support the restoration of methane deposits, and identified the main characteristics of microbes inhabiting depleted oil and gas fields. To evaluate the potential for microorganisms to inhabit oil and gas fields in Japan, we investigated the existence of methane-producing archaea (MPA) and hydrogen-producing bacteria (HPB) using PCR-DGGE (Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis) analysis. Reservoir brine from Yabase oil field (Akita Pref., Japan), which was incubated under strictly anaerobic conditions at 50°C, actively produced methane, indicating that Yabase oil field is a suitable site for methane generation. Moreover, analysis of the enrichment culture revealed that it is possible for indigenous anaerobes inhabiting an oil field to generate methane from oil components. Additionally, findings established a methanogenic pathway composed of MPA such as Methanoculleus sp., Methanothermobacter thermoautotrophicus, and Methanosaeta sp. and hydrocarbon-degrading hydrogen-producing bacteria (HD-HPB) related to Thermotoga sp., Petrotoga sp. and Clostridiaceae str. These results strongly suggest that Yabase oil field has the technological potential for the microbial restoration of methane.
Waste cooking oil contaminated with fish oil has potential uses as a biodiesel fuel feedstock. The changes in properties of fish oil fatty acid methyl ester (FAME) caused by oxidation were first evaluated, and the oxidation stability of fish oil FAME was improved by partial hydrogenation using a noble metal catalyst. Oxidation of fish oil FAME resulted in many decomposition products such as aldehydes, carboxylic acids and ketones, and large amounts of sludge. The oxidation propensity of FAME was proportional to the degree of unsaturation, and polyunsaturated FAMEs with more than 4 double bonds, the main components of fish oil FAME, were almost completely oxidized. Elemental analysis and FT-IR analysis showed that the sludge contained large amounts of oxygen compounds assigned as ketones, esters and carboxylic acids. Gel permeation chromatography (GPC) indicated that the sludge seemed to be formed by polymerization of about ten molecules of FAME, especially polyunsaturated FAME molecules. To improve the oxidation stability of fish oil contaminated biodiesel fuel, partial hydrogenation of fish oil FAME was carried out over Pd-Pt/Yb-USY-Al2O3 catalyst, with the fish oil FAME mixed with rapeseed oil to simulate the waste cooking oil contaminated with fish oil. Unsaturated FAMEs with more than 2 double bonds were selectively hydrogenated to monounsaturated and saturated FAMEs. Hydrogenated mixed FAME did not form any sludge and the oxidation stability was significantly improved compared with the untreated FAME. The oxidation stability of hydrogenated FAME blended with petroleum diesel was almost equivalent to that of petroleum diesel. Reduction of polyunsaturated FAME by partial hydrogenation is effective for improving the oxidation stability as well as suppression of sludge formation.
Reduction of waste materials has become very important in the petroleum industry. Sludge accounts for 51% of waste materials produced in petroleum plants. Most sludge is excess activated sludge discharged by wastewater treatment. We previously developed a new technology to solubilize excess sludge using a combination of alkaline solubilization and high speed mixing. The present study investigated the relationships between sludge solubilization and reduction of final amount of excess sludge based on model experiments with bench scale equipment. Amount of reduced excess sludge was increased with higher amount of solubilized sludge until the amount of solubilized sludge was lower than the excess sludge without solubilization. The amount of reduced excess sludge was approximately equal to the amount of solubilized sludge. COD and T-N concentrations in outlet water and removal rates were not changed with alkaline solubilization. Organic matter in the activated sludge was decreased with higher amount of solubilized sludge due to ash accumulation.
Asphaltene precipitation and deposition is one of the main problems in some of the oil fields. The deposited asphaltene results in partial or total blockage of the wellstring and reducing or completely seizing oil production. Asphaltene deposition problems have been experienced in the field for a long time. Although, the asphaltene precipitation has been studied thoroughly and different parameters that effects this process has been investigated but little work has been carried out in the asphaltene deposition across the production system of flowing oil well. This paper introduces a new comprehensive model for description of asphaltene deposition behavior in wellstring. The mechanisms of asphaltene deposition have been investigated experimentally using an accurate thermal approach. A series of experiments were conducted to observe the role of various parameters such as oil flow rate, temperature and concentration of asphaltene precipitant on the rate of asphaltene deposition. The model of asphaltene deposition was developed based on the results of experiments. There was good agreement between measured and predicted asphaltene deposition rate. Following this, the developed model was applied to an Iranian oil producer reservoir with severe problem with asphaltene deposition. The wellstring model couples the thermodynamic asphaltene precipitation with the developed model of asphaltene deposition. The model was able to predict the asphaltene plugging time properly, and determining the depth and the thickness of asphaltene deposition with respects to the production time. This paper offers readers with the first asphaltene deposition wellstring that uses thermodynamic of asphaltene precipitation and couples it with comprehensive deposition model.
The catalytic combustion of dibenzofuran and chlorobenzene, model compounds for dioxin, was investigated on Pt supported zeolite catalysts. Among transition metals, such as Pd, Au, Ni, etc., Pt supported on H-USY zeolite was the most active and stable for the combustion of dibenzofuran into CO2 and water at 573 K. The reduction treatment on Pt/H-USY before the reaction gave high activity compared with the oxidation treatment. The conversion of dibenzofuran was governed by the dispersion of Pt particles irrespective of the acidity and porosity of support materials including zeolites, mesoporous silica and silica gel. The combustion of chlorobenzene on Pt/zeolite proceeded at much higher temperature than that of benzene. The conversion of chlorobenzene was accelerated by the presence of water vapor in the reactant and the acid sites on zeolite. The activity of Pt/H-ZSM-5 for the combustion of polychlorodibenzofuran, one of dioxin, was discussed from the combustion results of dibenzofuran, chlorobenzene and benzene.
Hydroconversion of methylcyclohexane was conducted over various noble metal-loaded catalysts at 493 K and atmospheric pressure. On the bases of the proposed reaction route and the rate of reaction over Ir/H-β zeolite, which was the best catalyst examined, we concluded that the low yield of the desired dimethylpentanes (18%) and high yield of undesired methylhexanes (25%) were due to two reasons: (1) formation of ethylcyclopentane with high selectivity at low conversions and (2) higher ring-opening rate of ethylcyclopentane (a precursor of methylhexanes) than that of dimethylcyclopentanes (a precursor of dimethylpentanes). In order to improve the yield of dimethylpentanes, two catalysts for ring contraction from methylcyclohexane to ethyl- or dimethyl-cyclopentanes (Pt-H4SiW12O40/SiO2 or Pt/H-β) and for ring opening of the produced cyclopentanes (Ir/Al2O3) were used either in one reactor as a physical mixture or in two separate reactors connected in series. When the physical mixture (Pt-H4SiW12O40/SiO2 and Ir/Al2O3) was used, there was only a slight increase in the dimethylpentanes yield (20%) with a large amount of undesired products, such as monobranched heptanes and cracked products. In contrast, when two consecutive reactors packed with Ir/H-β and Ir/Al2O3 were used, the yield of dimethylpentanes increased to 30%, which was nearly two times of that of methylhexanes, at a 65% conversion of methylcyclohexane, while the yield of undesired methylhexanes was about 15%.
This preliminary study on the maintenance of industrial lubricants for chemical plant investigated appropriate maintenance through condition monitoring of the lubricants, in particular autoxidation of base oil as the major degradation process. Changes in chemical and physical properties caused by the autoxidation of hydrocarbons were considered in terms of reaction sequence. The roles of antioxidants for maintaining the quality of lubricants were also considered. The reaction mechanism suggested the importance of antioxidants in lubricants during service. Therefore, a new method to diagnose consumption of antioxidant was required. Organic peroxides are reactive species generated during the autoxidation of hydrocarbons at the initial stage and can be quantitatively analyzed by iodometric titration. The peroxide value (POV) is proposed as a new parameter to monitor conditions of lubricants. The POV trace was examined by a model oxidation test of lubricant in the laboratory. Subdivided addition of antioxidants to lubricant before an increase in POV was found to prolong the lifetime of the lubricants. POV in lubricants for compressors in chemical plant was monitored during the regular maintenance process for two years. Increased POV was observed during machine operation. Oil refill reduced the POV of the lubricant to some extent. Changes in total acid number (TAN) of lubricant were closely related to change in POV, whereas other parameters such as viscosity, insoluble contaminants and water contaminants seemed independent of the changes in POV. The utility of the POV trace depended on the conditions of machine operation, but provided early diagnostics of lubricant degradation in some cases.
A new method for ethanol synthesis from dimethyl ether (DME) and syngas via a two-stage reaction system was established successfully. In the first stage reaction, H-mordenite zeolite catalyst was used to convert DME into methyl acetate (MA) through carbonylation reaction. The MA produced from the first stage reactor was hydrogenated by Cu/ZnO catalyst in the followed second stage reactor to form ethanol and methanol. The effect of the variation of reaction temperatures on the products distribution for each stage reaction was investigated.
In order to investigate the influence of fatty acid methyl ester (FAME) on oxidative deterioration behavior of biodiesel mixed diesel fuel, FAME/tetradecane mixtures were prepared as model biodiesel/diesel mixtures and their oxidation tests were carried out. The mixed fuel containing FAME with more than two double bonds formed large amount of acid by the oxidation. The mixture containing methyl linolenate formed sludge and its acid value was high. The sulfur compound in the mixed fuel was oxidized and most of them were contained in the sludge.