Concentration Of Organic Sulfur Compounds Research Articles

MODEL PREDICTIVE CONTROL FOR PRODUCTION OF ULTRA-LOW SULFUR DIESEL IN A HYDROTREATING PROCESS

ABSTRACT There is a continual desire around the world to reduce the sulphur content of diesel fuel to ultra-low levels (below 10 ppm) due to environmental concerns and the intention of improving air quality and lowering harmful exhaust emissions of diesel engines. In this work, a hydrodesulfurization unit fed with multiple diesel streams was addressed using a phenomenological mathematical model aiming to produce Ultra-Low Sulfur Diesel (ULSD). A three-phase model of a trickle-bed reactor was considered. A model-based predictive control strategy (MPC) was implemented with the objective of controlling the sulfur concentration at the exit of the reactor, manipulating the flow rates of the oils entering the system, the superficial velocity of the gas and the temperature of the load in the presence of disturbances in the concentration of organic sulfur compounds in the fed oils. It was observed that the control strategy reduced the contaminant content to the specification range of diesel S10.

Influence of hydrocarbons and thiophene on catalytic fixed bed methanation

The economics of decentralized methanation units require a reduced complexity of the gas cleanup of gasification-derived syngas resulting in higher concentrations of organic sulfur compounds, e.g. thiophene. The influence of thiophene as single compound as well as in combination with higher hydrocarbons on catalytic fixed bed methanation has been experimentally examined in a series of bench-scale tests with a commercial Ni catalyst. The change of activity of the catalytic fixed bed was studied by methanation under well-defined reference settings. For intermediate catalyst treatment the impurities thiophene, as major sulfur species unremoved by acid gas scrubbing, as well as ethene and naphthalene as major hydrocarbon species in syngas, have been chosen. In all experiments thiophene addition showed a slow but steadily-ongoing deactivation of the catalytic fixed bed with catalyst consumption varying from 0.6 to 1.7 gcatalyst/mmolC4H4S. Addition of 1.0vol.% ethene to the feedgas resulted in significant increase of the pressure drop over the fixed bed, whereas simultaneous addition of thiophene and ethene, as well as single or combined addition of naphthalene, did not cause any increase of the pressure drop. The results were compared to the sulfur passivated steam reforming but in case of methanation no similar mechanism is likely to exist.

Analysis of organic sulfur compounds in atmospheric aerosols at the HKUST supersite in Hong Kong using HR-ToF-AMS.

Organic sulfur compounds have been identified in ambient secondary organic aerosols, but their contribution to organic mass is not well quantified. In this study, using a high-resolution time-of-flight aerosol mass spectrometer (AMS), concentrations of organic sulfur compounds were estimated based on the high-resolution fragmentation patterns of methanesulfonic acid (MSA), and organosulfates (OS), including alkyl, phenyl, and cycloalkyl sulfates, obtained in laboratory experiments. Mass concentrations of MSA and minimum mass concentrations of OS were determined in a field campaign conducted at a coastal site of Hong Kong in September 2011. MSA and OS together accounted for at least 5% of AMS detected organics. MSA is of marine origin with its formation dominated by local photochemical activities and enhanced by aqueous phase processing. OS concentrations are better correlated with particle liquid water content (LWC) than with particle acidity. High-molecular-weight OS were detected in the continental influenced period probably because they had grown into larger molecules during long-range transport or they were formed from large anthropogenic precursors. This study highlights the importance of both aqueous-phase processing and regional influence, i.e., different air mass origins, on organic sulfur compound formation in coastal cities like Hong Kong.

Sulfur poisoning of molybdenum dioxide during the partial oxidation of a Jet-A fuel surrogate

The aim of the present work is to investigate the effect that organic sulfur compounds have on the catalytic performance of molybdenum dioxide (MoO2) during the partial oxidation reaction of aviation fuels. N-dodecane and benzothiophene were used as surrogates for Jet-A fuel and as a model sulfur compound, respectively. Activity tests of commercial MoO2 toward the partial oxidation reaction of this model Jet-A fuel were performed at 850°C. Our studies indicate that MoO2 displays a remarkable tolerance to deactivation by organic sulfur compounds even at concentrations as high as 1000ppmw, a typical sulfur concentration found in aviation fuels. However, commercial MoO2 catalysts show a significant catalytic performance deactivation as the concentration of organic sulfur compounds increases to 3000ppmw. TEM and XPS data indicate that the deactivation process starts with the formation of Mo sulfide on the catalyst surface. The sulfide phase appears to reduce the ability of the catalyst to activate hydrocarbon molecules as well as impeding the ability to deliver lattice oxygen to the active surface sites, which leads to the enhancement of side reactions that promote the formation of coking. The catalyst deactivation resulting from the exposure to such high concentrations of organic sulfur compounds appears to be reversible with an air treatment at 850°C. The catalyst activity of MoO2 recovers approximately 80% of its initial performance as demonstrated by the H2 yield and TEM data.

Chicken manure increased concentration of organic sulfur compounds in field-grown onions

A field study was conducted at Kentucky State University (KSU) Research Farm. The soil in five plots was mixed with sewage sludge, five plots were mixed with yard waste compost, five plots were mixed with laying hen manure each at 15 t acre−1, and five unamended plots that never received soil amendments were used for comparison purposes. Plots were planted with onion, Allium cepa L. var. Super Star-F1. The objectives of this investigation were to: 1) determine the concentrations of two organosulfur compounds (dipropyl disulfide and dipropyl trisulfide) in onion bulbs and 2) investigate the effect of mixing soil with three amendments (sewage sludge, yard waste, and chicken manure) on the concentration of dipropyl disulfide and dipropyl trisulfide in onion bulbs. Gas chromatographic/mass spectrometric (GC/MS) analyses of onion oil in chloroform extracts revealed the presence of two major fragment ions that correspond to dipropyl disulfide and – trisulfide. Concentration of these two organic sulfur compounds was greatest (1.5 and 0.8 mg 100 g−1 fresh weight, respectively) in onion bulbs of plants grown in chicken manure and lowest (0.4 and 0.07 mg 100 g−1 fresh weight, respectively) in onion bulbs of plants grown in yard waste compost treatments. We concluded that chicken manure could be exploited in growing onions with health-promoting properties.

Identification of Odor‐Active Organic Sulfur Compounds in Gypsum Products

AbstractGypsum is widely used in building products, e. g., as drywall, stucco or constituent in mortar, because it is easy to handle and it is assigned creating a good indoor air quality. Odor analysis of a gypsum product with a sulfurous off‐odor by means of gas chromatography‐olfactometry compared to two unobtrusive commercial gypsum products revealed – apart from typical odor compounds previously found in building products like aldehydes, ketones and acids – various organic sulfur compounds as odorants at very small concentrations (≪1 μg/m3) not allowing structural identification. Gypsum deposits naturally contain impurities and elemental sulfur, which can react in nature due to tectonic pressure and temperature or during production with organic compounds, e. g., from beater additives, to form organic sulfur compounds. Odor analysis of a gypsum raw material and its semi‐processed product from a Chinese deposit with a very intense sulfurous off‐odor revealed high concentrations of organic sulfur compounds, which were identical in analytical, chromatographic and sensory properties to the unidentified sulfur compounds of the commercial products and are therefore suitable for structural identification of those unknowns. In this way, a number of sulfides, disulfides, thiols and aromatic sulfur compounds could be identified as contributing to the odor of gypsum products.

Identification of volatile (micro) biological compounds from household waste and building materials by thermal desorption–capillary gas chromatography–mass spectroscopy

AbstractVolatile compounds from biodegradable household waste and infected building materials have been studied by dynamic or equilibrium headspace sampling and concentration on Tenax TA followed by thermal desorption and HRGC‐MS. Equilibrium headspace sampling was also used to study vegetables stored for 14–18 days at ambient temperature. Over 200 compounds were tentatively identified. The concentration of organic sulfur compounds from garden waste was high enough to contribute to respiratory problems of waste handling personnel. Nitriles, alkyl nitro compounds, and alkyl nitrates were isolated from radish and carrot samples at low concentrations (10–50 ppb). Air monitoring in waste handling working environments may be required to ensure the safety of personnel. Branched aliphatic aldehydes, carboxylic acids, esters, and 2‐alkanones were found in the headspace of the infected building materials, indicating that volatile compounds may be useful for detection of microbial growth in buildings.

Influence of the association of organic sulfur compounds with aromatic hydrocarbons on the resistance of oil to oxidation

1. Changes in the adsorption capacity of organic sulfur compounds with respect to silica gel, with change in concentration and chemical structure of hydrocarbons contained in the oil, points to the formation of associations composed of aromatic hydrocarbons and organic sulfur compounds. 2. Periodic weakening of the antioxidizing properties of sulfur-containing oils with addition of polycycllc aromatic hydrocarbons points to the fact that in sulfurous oils, the antioxidizing functions are performed by associated systems containing aromatic hydrocarbons and organic sulfur compounds. 3. The composition of micelles having antioxidizing properties is not constant and is a function of the concentration and chemical structure of their components. Increase in the aromatic hydrocarbon concentration with the concentration of organic sulfur compounds being constant, at first, results in the growth of micelles and later in their disintegration. In conformity with the change in composition and concentration of antioxidant micelles, the stability of the oil also changes.

STUDIES ON THE GAS CHROMATOGRAPHIC DETERMINATION OF MERCAPTANS.

A series of partitioning agents were studied to determine their ability to separate organic sulfur compounds by gas chromatography. Several columns showed promise, but did not separate organic sulfur compounds from normally occurring atmospheric hydrocarbons. Higher concentrations of organic sulfur compounds in stack gases are separated as metallic salts in a series of impingers. The nature of the precipitated sulfur compound can be determined by gas chromatography after regeneration of the compound by addition of acid to the metallic precipitate.

各種メタン改質触媒に対する有機イオウ化合物の許容濃度

各種メタン改質触媒に対する有機イオウ化合物の許容濃度