Varying Sulfur Content Research Articles

A solid-state NMR, FT-IR and TPD study on acid properties of sulfated and metal-promoted zirconia: Influence of promoter and sulfation treatment

The acid properties of various sulfated and metal-promoted zirconium oxide (ZrO 2) catalysts have been studied by solid-state 31P MAS NMR, FT-IR and TPD using the adsorbed trimethylphosphine oxide (TMPO), pyridine and ammonia as the probe molecule, respectively. Sulfated zirconia (SZ) catalysts having varied sulfur contents and metal promoter (M = Al, Ga and Fe) were prepared by sol–gel method. Effects of sulfation and promoter on the detailed qualitative and quantitative information of acid sites, viz. types (Brønsted versus Lewis), strengths and distributions, on various synthesized SZ and M/SZ were examined by 31P MAS NMR of adsorbed TMPO in conjunction with elemental analyses by ICP-MS. By comparison, pyridine-IR and NH 3-TPD methods are capable of providing only qualitative information of the overall acidity. It was found that while the parent ZrO 2 possesses only weak Lewis acidities, elaborated sulfation treatment leads to formation and coexistence of strong Brønsted (B) and Lewis (L) acid sites whose variations can readily be followed. On the other hand, incorporation of different metal promoters onto SZ, led to simultaneous formation/elimination and variations of B- and L-sites with varied strengths and distributions. As a result, Ga/SZ was found to possess more B- than L-sites, whereas an opposite trend was observed for Al/SZ. As for Fe/SZ, a pronounced increase in both concentration and strength of acid sites were found. With an exception of Ga/SZ, the ‘very strong’ acid sites observed for various SZ and M/SZ catalysts were found to be associated more to L- than B-sites.

パーオキサイド架橋ＥＰＤＭの構造と動的特性に関する研究 第４報 ハーンエコー法によるイオウ架橋ＥＰＤＭの構造解析

Sulfur-crosslinked EPDMs were examined by 1H pulsed NMR. Spin-spin relaxation time (T2) was measured by Hahn echo method. The decay curve was resolved into two components, T2n and T2nn, which were arising from network molecules and non-network molecules, respectively. For unfilled EPDMs prepared at varying sulfur content, the higher order structures analyzed by Hahn echo method were almost the same as those analyzed for peroxide-crosslinked EPDMs. The reciprocal of Ten measured at 150°C for unfilled EPDMs increased linearly with increase in apparent crosslinking density (νs) values determined by modified Flory-Rehner equation. For EPDMs filled with carbon black (CB), the crosslinking density of rubber phase (νR) was calculated from the relationship between νs and 1/T2n for unfilled EPDMs. The crosslinking density related to CB (νF) was obtained from the difference between the νs and νR. The νF values showed good correlation with the tensile stress at 100% elongation, independent of the kinds of cure agents.

Surface effects and flow conditions in small volume melts with varying sulphur content

The surface effects and flow behaviour in melts with a volume of a few cubic millimetres were investigated using 1 mm thick X5CrNi18‐9 (AISI 304) stainless steel strips after partial remelting by a TIG (tungsten inert gas) burner. In the industrially produced material the S mass content was varied between 20 and 100 ppm. The surface excess of sulphur indicates that the surface saturation was not achieved compared to the values in the Fe‐S system. The thickness of the layer with high sulphur enrichment depends on the S activity and varied between approximately 260 and 460 nm and achieves the bulk S content at a distance of approximately 1.2 μm from the surface. This layer is noticeably thinner than the diffusion boundary layer and considerably thinner than the flow boundary layer. The topography of the rapidly solidified liquid pool makes it possible, taking previously estimated temperature coefficients of surface tension into account, to explain the flow behaviour in the melt with regard to the S content and to the temperature gradients. The results obtained indicate that the shearing force caused by surface tension gradients (Marangoni effect) controls the flow conditions in small volume melts.

97/01488 U.S. Army investigation of diesel exhaust emissions using JP-8 fuels with varying sulfur content

97/01488 U.S. Army investigation of diesel exhaust emissions using JP-8 fuels with varying sulfur content

A new engine oil optimised for ecologically sensitive operational areas

AbstractIn recent years, environmental awareness and legislation have focused public attention on vehicle emissions. Consequently, more research has been devoted to emissions and pollution by lubricants. A number of studies has been carried out to understand lubricant‐related emissions and leak rates as well as the effects on fuel economy of using low viscosity grades of lubricant. The purpose of the present investigation was to develop for use in gasoline and diesel engines a crankcase lubricant which contained improved performance in engine cleanliness with fuel economy and a low rate of particle emissions. Emphasis was placed on low toxicology and rapid biodegradability because of the risk of unintentional emissions. Such a sophisticated lubricant is desirable not only for normal road vehicles but also and especially for use in ecologically sensitive areas.During the development of this lubricant, numerous laboratory tests were performed. In order to assess the quality and the fuel economy of the new lubricant, tests were carried out on an engine test rig and on a vehicle test bench. Field tests were run with various vehicles and stationary engines, using different fuel types. Unleaded gasoline, diesel fuels with a varying sulphur content, and rape seed oil methyl ester (RME) were used. This paper summarises the results of this investigation.

Effect of Complex Inclusions on Pit Initiation in 18% Chromium-8% Nickel Stainless Steel Types 303, 304, and 321

Abstract Several grades of 18% chromium-8% nickel stainless steel (SS) with varying sulfur contents and immersed in 3% sodium chloride (NaCl) demonstrated essentially passive behaviors, with local ...

Molecular characterization of organically‐bound sulfur in crude oils. A feasibility study for the application of Raney Ni desulfurization as a new method to characterize crude oils

AbstractFive crude oils with varying sulfur contents (0.1 – 4.7%) were characterized on a molecular level for organically‐bound sulfur. Aromatic fractions were analyzed by GC‐(MS) and asphaltene and polar fractions were analyzed by flash pyrolysis‐GC‐(MS). The polar fractions were also desulfurized with Raney Ni and the hydrocarbons formed were analyzed by GC‐MS. Major sulfur compounds in the aromatic fractions were identified as alkylbenzo‐ and alkyldiben‐zothiophenes. The flash pyrolyzates of the asphaltene contained alkylthiophenes and alkylbenzothiophenes as major compounds, depending on the thermal maturity of the oil. Generally, the sulfur‐rich crude oils contained relatively more sulfur compounds. The flash pyrolyzates of polar fractions contained a variety of sulfur compounds (alkylthiolanes, alkylthianes, terpenoid sulfides, alkylbenzothiophenes) with substantial differences between different crude oils. Raney Ni desulfurization of the polar fraction yielded hydrocarbons dominated by n‐alkanes, but isoprenoid alkanes, n‐alkylcyclohexanes, mid‐chain methylalkanes, tricyclic terpanes, hopanes and steranes were also present. These hydrocarbons show a potential to fingerprint crude oils since their distribution patterns are more characteristic than those of the hydrocarbons present in the saturated hydrocarbon fraction.

Quantitative analysis of the major saccharides in sulfite-treated wood pulps by pyrolysis-gas chromatography: The effect of metal ions

It has previously been shown that pyrolysis-gas chromatography can be used to quantify the glucose and xylose contents of a variety of wood pulps by measurements of their individual anhydrosugar products. However, lower than expected yields of anhydrosugars were obtained from sulfite-treated pulps. Levoglucosenone is the major pyrolysis product observed and it is speculated that its production is catalyzed by the sulfonic acid groups present in the pulp. By incorporating certain transition metal ions into the pulp by ion exchange, anhydrosugar production is greatly enhanced and levoglucosenone is nearly eliminated from the pyrogram. The best yields of anhydrosugars are obtained from Fe 2+- and Fe 3+-exchanged pulps. The major saccharides present in a number of Fe 2+-exchanged sulfite pulps were successfully quantified using pyrolysis-gas chromatography and the results were found to correlate well with the saccharide measurements acquired by acid hydrolysis/derivatization-gas chromatography analysis. It was also found that the varying sulfur content, which was used as an indirect measure of the sulfonic acid composition, and iron incorporated into the pulps under investigation had little effect on the pyrolysis results. The CDS Pyroprobe Model 120 pyrolyzer was modified in order to improve the accuracy and reproducibility of analytical pyrolysis.

Compositional dependence of photoluminescence spectra in hydrogenated amorphous silicon-sulfur alloys

Photoluminescence (PL) measurements were performed on films of amorphous silicon-sulfur alloys with varying sulfur contents. The incorporation of sulfur leads to a decrease in low temperature PL efficiency, indicating an increase in the overall defect density. The full width at half maximum increases while the PL peak position shows no significant change. Together with previous results from photocurrent spectroscopy it is concluded that the valence band tails broaden. In addition PL properties were measured as a function of temperature. With increasing sulfur content a progressively weaker dependence of PL efficiency and peak position on temperature is found.

Clinical and ultrastructural studies in duodenal pseudomelanosis.

Nine patients with duodenal pseudomelanosis are described: seven had endstage renal failure while one other patient had undergone renal transplantation. Eight of the nine had been on oral iron supplements. The pigment stained positively with Perls' stain for iron in five patients, positively with the Masson-Fontana method normally used to identify melanin in one, and positively with both methods in three. Electron probe x-ray analysis of the pigment on samples from six patients showed iron to be present in all six, while sulphur was present in five. Varying sulphur content of the pigment in different patients could account for differences in histochemical characteristics. Iron was also shown in the duodenal biopsies of 34 of 48 uraemic patients on oral iron supplements, but was present in only 22 of 120 patients endoscoped for miscellaneous conditions (p less than 0.001). We postulate that the pigment of duodenal pseudomelanosis is derived from iron absorbed from the lumen.

Mutagenic and cytogenetic analyses of organic extracts of simulated runoffs from model coal piles.

The use of coal as a fuel in utility and other industries in the United States is increasing. Typically, these utilities store their coal outdoors in large piles, and rainfall on the piles produces a runoff containing hazardous inorganic and organic materials. Four coals of varying sulfur contents, all used for fuel in the United States, were tested. Organic materials were extracted from simulated runoffs of model coal piles and were tested for mutagenicity with a Salmonella/microsomal assay and for clastogenicity and cytotoxicity in Chinese hamster ovary cells. The extracts of the high-sulfur coals and the lignite were more mutagenic and clastogenic than extracts from the low-sulfur coal.

Optimal Location of Coal Blending Plants by Mixed-Integer Programming

Abstract In order to meet increasingly stringent environmental standards, coal burned by utilities and industries must be of an acceptable lower sulfur content. One solution suggested in this paper is the establishment of centralized blending plants that could take coals of varying sulfur content and produce a coal product that would meet the coal consumers needs based upon effluent standards. A mixed integer programming model is developed for studying this problem. A case study is presented with coal data for the State of Indiana. Model results on the number of blending plants to be selected, their site locations, optimal blending ratios, transportation configuration, and cost savings are discussed.

Through-thickness Brittle Fracture and Fatigue Properties in High Strength Structural Steels with Varying Sulphur Content

Through-thickness Brittle Fracture and Fatigue Properties in High Strength Structural Steels with Varying Sulphur Content

Microstructure of glasses in the system As 2S x with x < 3

AsS compositions with varying sulfur content, melted in evacuated sealed tubes, were subjected to X-ray powder diffraction, density measurement, micro-Vickers hardness test, differential thermal analysis, electron microscopic observation and electron probe X-ray microanalysis. The glass-forming region has been determined. Structure of glasses has been discussed on the basis of the results of the measurements. It was suggested that the glass structure changed sharply at a composition between As 2S 2.6 and As 2S 2.7; glass-glass phase separation occurred when the sulfur content was lower than the As 2S 2.67 composition.

Methods of preparation of sulfanes

Sulfane crude oils obtained by acidification of aqueous sodium polysulfide solutions vary little in composition with varying sulfur content of the solution. Evidence presented suggests that the distribution of the sulfanes in such crude oils reflects the equilibrated distribution of the various polysulfide anions in the aqueous solution before acidification. The sulfane distribution in mixtures obtained by reaction of liquid H2S with Br2, SCl2, and S2Cl2 respectively varies over a wide range, depending on the molar ratio of the reactants. Liquid H2S reacts with Br2 or SCl2 to yield essentially the same products. These reactions, however, differ in the nature of their intermediates. By using a large excess of liquid H2S, H2S3 was directly synthesized in over 90% purity. Liquid H2S reacts with S2Cl2 to yield H2S4 in over 90% purity. Gaseous HCl catalyzes the reaction of H2S with the chlorosulfanes and a mechanism is suggested involving HCl as a proton transfer agent in the formation of the reactive intermediates.

Inhibition of Acid Attack on Steel by Heavy Metal Ions

Ions of lead, tin, and cadmium were shown to inhibit the dissolution of steel in acid solutions in the absence of metal plating. A mechanism was postulated whereby sulfide ions produced by metal dissolution combined with the heavy metal ions to form a protective coating on the dissolving surface. Analytical studies indicated that both lead and tin ions were removed from acid solutions in contact with iron filings, in quantities too great to be explained by adsorption. Studies on the effect of increased acid concentration and varying sulfur content of the dissolving metal tended to substantiate the mechanism. The order of effectiveness of inhibition of ions of lead, tin, and cadmium was shown to coincide with the order of solubility of the respective metal sulfides.

鋳鉄の組織図の研究（第3報）硫黄の影響を考慮した鋳鉄の組織図

鋳鉄の組織図の研究（第3報）硫黄の影響を考慮した鋳鉄の組織図

IV. p-Bromophenylmercapturic Acid and Ethereal Sulfates Synthesis in Dogs Maintained on Diets of Varying Sulfur Content

Summary1. Dogs were fed diets of varying sulfur content and 1.0 gm. doses of bromobenzene were fed on 4 consecutive days on each of the diets. The synthesis of p-brornophenylrnercapturic acid and ethereal sulfates on these diets was estimated. 2. The extent of the synthesis of the mercapturic acid and of the ethereal sulfates is apparently a function of the nutritive state of the animal: when the animal was deprived of dietary sulfur, a decrease in the output of mercapturic acid and an increase in the output of ethereal sulfates was noted. 3. The results offer further support to the previous suggestion that the dietary sulfur is not the immediate source which is used for the detoxication of blromobenzene in dogs.