Abstract The development of the existing CEN methodology started with the improvement of the 1991... more Abstract The development of the existing CEN methodology started with the improvement of the 1991 Nordtest method, which resulted in CEN guidelines published in 2006 and 2012. While the Nordtest method was based on a visual comparison, the original CEN 2006 guideline introduced quantitative compound ratios to achieve a more robust final conclusion that was less dependent on the experience of the analyst. The CEN 2012 guideline, which has superseded the CEN 2006 guideline, subsequently introduced a product-specific list of normative ratios and the use of percentage weathering (PW) plots in order to ensure good analytical performance and evaluate weathering and mixing. The first time reductions of compounds (e.g., due to weathering within a spilled oil) were properly recognized as such, and allowed corresponding weathering-driven differences to actually contribute to the proof that the samples had been identical at the time of the discharge. This chapter summarizes and highlights from the existing CEN 2012 guideline, which has been prepared by Bonn-OSINet, a worldwide group of experts collaborating on oil spill identification.
Biocrudes contain more oxygen and are less thermally stable than petroleum intermediates resutlin... more Biocrudes contain more oxygen and are less thermally stable than petroleum intermediates resutling in higher hydrogen consumption and accelerated catalyst deactivation during upgrading into biofuels.
An analytical method providing high sensitivity (limit of quantitation of 50 ng/l) with acceptabl... more An analytical method providing high sensitivity (limit of quantitation of 50 ng/l) with acceptable reproducibility (mean R.S.D. 19%) has been developed for determining heteroaromatic compounds in creosote-contaminated groundwater. The best technique (highest recovery and reproducibility) found between liquid-liquid extraction using either dichloromethane, diethyl ether or pentane and solid-phase extraction with reversed-phase bonded columns, was the classical liquid extraction with dichloromethane from weak basic solutions and GC-MS (selective ion monitoring) analysis of concentrated extracts.
Ground Water Monitoring and Remediation, May 1, 1997
The occurrence of heteroaromatic compounds (NSO) and their degradation products in ground water a... more The occurrence of heteroaromatic compounds (NSO) and their degradation products in ground water at creosote‐contaminated sites in Denmark was investigated. NSO are of special interest because of their high polarity, toxicity, and adverse organoleptic properties. In total, the content of about 50 organic tar compounds and the chemical redox parameters of ground water from three creosote‐contaminated sites were determined.The organic contamination of ground water varied considerably between sites and wells with concentrations up to mg/L level. The major organic contaminants were NSO, phenols, and monoaromatic hydrocarbons, which are among the most water‐soluble creosote compounds. High concentration (several μg/L) of these compounds were observed downgradient of the contamination source. Within a distance of 50 to 80 m from the source, the concentrations of most compounds were reduced significantly, often below detection limits. The NSO constituted from 0.1 percent to 73 percent of all organic compounds determined by gas chromatography (GC) with an increasing dominance downgradient of the source. Among the 17 studied NSO, carbazole, thiophene, benzothiophene, dibenzothiophene, benzofuran, and dibenzofuran were observed most frequently (detection frequency > 60 percent). High concentrations (>100 μ/L) of some NSO such as benzothiophene, carbazole, hydroxyquinolines, and basic N‐compounds were observed occasionally. Other recent studies on creosote contamination support the present observations of high ground water concentrations of basic N‐compounds and the high detection frequency of the aforementioned NSO. However, unlike the other studies, we did observe thiophene (1‐10 μg/L).
Abstract The development of the existing CEN methodology started with the improvement of the 1991... more Abstract The development of the existing CEN methodology started with the improvement of the 1991 Nordtest method, which resulted in CEN guidelines published in 2006 and 2012. While the Nordtest method was based on a visual comparison, the original CEN 2006 guideline introduced quantitative compound ratios to achieve a more robust final conclusion that was less dependent on the experience of the analyst. The CEN 2012 guideline, which has superseded the CEN 2006 guideline, subsequently introduced a product-specific list of normative ratios and the use of percentage weathering (PW) plots in order to ensure good analytical performance and evaluate weathering and mixing. The first time reductions of compounds (e.g., due to weathering within a spilled oil) were properly recognized as such, and allowed corresponding weathering-driven differences to actually contribute to the proof that the samples had been identical at the time of the discharge. This chapter summarizes and highlights from the existing CEN 2012 guideline, which has been prepared by Bonn-OSINet, a worldwide group of experts collaborating on oil spill identification.
Biocrudes contain more oxygen and are less thermally stable than petroleum intermediates resutlin... more Biocrudes contain more oxygen and are less thermally stable than petroleum intermediates resutling in higher hydrogen consumption and accelerated catalyst deactivation during upgrading into biofuels.
An analytical method providing high sensitivity (limit of quantitation of 50 ng/l) with acceptabl... more An analytical method providing high sensitivity (limit of quantitation of 50 ng/l) with acceptable reproducibility (mean R.S.D. 19%) has been developed for determining heteroaromatic compounds in creosote-contaminated groundwater. The best technique (highest recovery and reproducibility) found between liquid-liquid extraction using either dichloromethane, diethyl ether or pentane and solid-phase extraction with reversed-phase bonded columns, was the classical liquid extraction with dichloromethane from weak basic solutions and GC-MS (selective ion monitoring) analysis of concentrated extracts.
Ground Water Monitoring and Remediation, May 1, 1997
The occurrence of heteroaromatic compounds (NSO) and their degradation products in ground water a... more The occurrence of heteroaromatic compounds (NSO) and their degradation products in ground water at creosote‐contaminated sites in Denmark was investigated. NSO are of special interest because of their high polarity, toxicity, and adverse organoleptic properties. In total, the content of about 50 organic tar compounds and the chemical redox parameters of ground water from three creosote‐contaminated sites were determined.The organic contamination of ground water varied considerably between sites and wells with concentrations up to mg/L level. The major organic contaminants were NSO, phenols, and monoaromatic hydrocarbons, which are among the most water‐soluble creosote compounds. High concentration (several μg/L) of these compounds were observed downgradient of the contamination source. Within a distance of 50 to 80 m from the source, the concentrations of most compounds were reduced significantly, often below detection limits. The NSO constituted from 0.1 percent to 73 percent of all organic compounds determined by gas chromatography (GC) with an increasing dominance downgradient of the source. Among the 17 studied NSO, carbazole, thiophene, benzothiophene, dibenzothiophene, benzofuran, and dibenzofuran were observed most frequently (detection frequency > 60 percent). High concentrations (>100 μ/L) of some NSO such as benzothiophene, carbazole, hydroxyquinolines, and basic N‐compounds were observed occasionally. Other recent studies on creosote contamination support the present observations of high ground water concentrations of basic N‐compounds and the high detection frequency of the aforementioned NSO. However, unlike the other studies, we did observe thiophene (1‐10 μg/L).
Typical diesel fuel upgrading feeds consist of mixtures of straight run gas oils and light cycle ... more Typical diesel fuel upgrading feeds consist of mixtures of straight run gas oils and light cycle stocks. These feeds are composed of a variety of hydrocarbon types that have diverse properties. They contain high concentrations of low Cetane Number aromatics as well as sulfur and nitrogen impurities. When upgrading such feeds to produce specification diesel products each hydrocarbon class can respond differently to the catalysts and conditions used in the upgrading process. The goal of the present study was to determine how each hydrocarbon class responded to conditions that was optimal for ring opening reactions (RIO) of partially hydrogenated alkylaromatic ring systems. Promotion of this reaction required dual functional catalysts composed of metal/solid acid catalysts and mild reaction conditions. A detailed investigation of the mechanisms and product selectivities involved in the attempted RIO of saturated naphthenes and dinaphthenes under these conditions showed that the potential for upgrading diesel fuels by this approach has little incentive. The very fast competitive side reactions such as ring isomerization, ring contraction, alkyl group isomerization, dimer formation and cracking of the diesel boiling range feed components produced products that had fuel qualities, such as Cetane Number, lower than that of the starting materials. However, RIO of alkyldiaromatic hydrocarbons showed that partial hydrogenation of diaromatic structures to hydromonoaromatic structures followed by ring opening of the derived tetralins offered some potential for upgrading diesel feedstocks. Limitation of the overall conversion of alkyldiaromatics and alkyltetralins to less than 70% minimized the loss of diesel yields by secondary cracking of the desired alkylbenzene products. Moderate temperatures (~300 o C) and high hydrogen pressures (50 bar) produced the most desirable results. More condensed aromatic ring structures were found to respond even more favorably in a study which the polyaromatic ring compounds were concentrated by fractional distillation, then the heavy distillate was chromatographically separated into 10 different fractions containing different hydrocarbon classes. Each concentrate was then separately converted under standard RIO conditions. This study provided a basis for considering if selective separation and RIO processing of specific hydrocarbon classes would provide higher yields and higher quality products than RIO processing of whole feeds. Feeds and products were extensively characterized to accurately determine reaction selectivity for each hydrocarbon class. Under these conditions it was observed that paraffinic naphthenic components of diesel upgrading feeds are severely cracked to products out of the diesel fuel range under conditions necessary for RIO of hydroaromatic ring structures. Di-and poly-aromatic hydrocarbons underwent RIO with good selectivity.
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Papers by Asger B Hansen