Correlation between oil yields of oil shales and 13C nuclear magnetic resonance spectra

Using the cross polarization/dipolar decoupling method, ¹³C n.m.r. spectra have been obtained on twenty oil shales and kerogens from around the world. A correlation is found between the integrated signal intensity of the aliphatic region of the spectra and the oil yields of the shales.     

E.s.r. spectra of eastern oil shales

E.s.r. spectra of several oil shales from eastern and western USA have been measured at 9 and 25 GHz. The spectra of the western shales were similar to previously reported spectra and consist of a Mn²⁺ signal and a featureless organic signal. The eastern spectra consist of a V⁴⁺ signal and a complex and unusual organic signal consisting of at least four component signals. The organic signal has been characterized in terms of g factor, line-width and saturation characteristics. The effect of oxygen on the signal has also been examined. Electron nuclear double resonance (ENDOR) signals have been obtained from the organic signals of the eastern oil shales.     

Electrical conductivities and electron spin resonance spectra of polyaniline salts with different counteranions

Summary Electrical conductivities and ESR spectra were obtained for polyaniline salts that contained different counter anions. The electrical properties were markedly different from one salt to another, although the concentrations of counteranions were almost identical. The ESR spectra showed that different types of unpaired electrons were created upon protonation. There was a close correlation between the charge-transport property and the nature of unpaired electrons created upon protonation.     

Tocotrienols from palm oil: Electron spin resonance spectra of tocotrienoxyl radicals

The major vitamin E components present in palm oil, viz. α-tocopherol, α⁻, ψ-and δ-tocotrienols, have been isolated and their structures verified by the NMR spectra of their acetate and succinate derivatives. Oxidation of γ-and δ-tocotrienols with alkaline K₃Fe(CN)₆ gave isolable dimeric species, which were studied by¹³C NMR. Free radicals generated from the monomeric and dimeric tocotrienols were investigated using ESR spectroscopy. The distinction between antioxidant activity and antioxidant capacity of vitamin E isomers is discussed.     

Characteristics of processed shales affecting oil yield loss to coke

The objective of this research was to further examine coking during hot-solid recycle retorting. Specifically the relationship between process-induced macroporosity and the reactivity of the shale mineral matrix was investigated. Photomicrographs support a direct relation between coking and the development of macroporosity in oxidized substrates. As access to the mineral matrix increases, the effect of processing on its reactivity becomes more important. The coking activity of illite, the major mineral component of the shale used, increased slightly when heat-treated to 973 K, but further heat treatment to 1323 K decreased its reactivity. Coke deposited on combusted shale and illite either blocked access to and/or deactivated coking sites, significantly reducing substrate reactivity. Carbon removal from the illite by oxidation at 773 K increased reactivity threefold over untreated illite. Combusted shale had fewer active coking sites, as measured by temperature-programmed desorption analysis, than gasified shale. This was consistent with deactivation of the mineral matrix with increased temperature treatment. Results also indicated that deactivation of the mineral matrix was possible by heat and steam treatments. The data provided further evidence that the amount of oil yield loss to coke was primarily controlled by process-induced macroporosity, allowing access to a reactive mineral matrix.     

Interaction between coal and liquefaction catalysts studied by high temperature electron spin resonance

The high temperature electron spin resonance technique has been used to obtain in situ information on the behaviour of liquefaction catalysts during coal pyrolysis. The spin concentration in coal was induced in the presence of a catalyst at the pyrolysis temperature. ZnCl₂ drastically increased the spin concentration of coal. The order of activity of the catalysts with respect to the increase in spin concentration was: ZnCl₂ (impregnated) ?ZnCl₂ (dispersed) >ZnCl₂/KCl>SnCl₂ > SbCl₃≈AlCl₃ ≈CaCl₂ > coal alone.     

Analysis of rich oil shales by 1H nuclear magnetic resonance

The potential yields of rich oil shales from the Colorado Green River Basin were measured by pulsed ¹H nuclear magnetic resonance. The rates of decay of the signals, as quantified by their second moments, decreased with increasing organic content. This implies that whenever shales of widely varying yields are being compared, their free-induction-decays must be extrapolated to time zero.     

Trace elements in black and oil shales

Data on the abundance of trace elements in oil and black shales, as well as and the average concentrations of trace elements in these caustobioliths, are considered. In general, oil shales are enriched in Li, Be, B, Rb, Ta, and Se and depleted in Mo, Re, Ag, Au, V, Th, Cu, Hg (and, perhaps, W, As, and U) relative to black shales. Tentative values of minimal concentrations of trace elements oil shales are presented that make the integrated processing of shale organic matter economically viable to obtain by-product concentrates of valuable trace elements useful as feedstock for their recovery.     

Minerals in some Australian oil shales

The mineral composition of oil shales from three widely different ateas within Australia has been examined by X-ray diffractometry after low-temperature ashing. Quartz is more abundant than calcite. Feldspar is prominent in the Permian oil-rich shale from Glen Davis, New South Wales. Clay minerals are represented by smectite, illite, kaolinite and mixed-layer minerals (mostly mica-smectite). The content of clay minerals is generally low, except in the Tertiary oil shale from Rundle, Queensland.     

Molecular mobility in starchy materials studied by electron spin resonance

Phase transitions in hydrated starch–sorbitol system were investigated both by molecular (electron spin resonance, ESR) and macroscopic (differential scanning calorimetry, DSC) methods. In rapid‐tumbling region, one did not observe the same phenomena by DSC and by ESR. The transitions observed by ESR, which seemed to reflect more the interactions probe–matrix than plasticization, probably corresponded to the interactions probe–sorbitol. For system concentrated in plasticizer, it was conceivable to admit that a demixion of sorbitol occurred. In slow‐tumbling region, a correspondence in temperature mobility changes measured by mechanical spectroscopy and ESR was observed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 990–997, 2003     

Electrical conductivity and electron spin resonance studies of pyrolysed polyimide

Recent studies of polymer-based pyrolytic amorphous carbon for use in organic electrolyte-lithium batteries and as metal-doped carbon electrodes show considerable promise. Polyimide can be thermally converted to amorphous carbon films. The irreversible evolution of polyimide under progressive heat treatment is characterized by three successive structural changes: pyrolysis, carbonization and graphitization. Four-point contact conductivity and electron spin resonance (e.s.r.) measurements were used to study and correlate electrical conductivity changes with unpaired electrons. From these studies it is concluded that at low pyrolysis temperature (<650°C) the pyrolysed polyimide is a nonmetallic amorphous carbon incorporating residual oxygen and nitrogen. At higher pyrolysis temperatures (>700°C) a microcrystalline graphite-like metallic domain starts to appear in the amorphous matrix. The development of this ‘metallic domain’ causes the conductivity of the pyrolysed polyimide to increase sharply.     

Structural study of a varnish by electron spin resonance

Related to the study of interactions between food and aluminum cans, structural features of a vinylic organosol coating were studied by electron spin resonance (ESR). Paramagnetic probes were incorporated separately in the normal formulation of a widely used varnish, which was then cured at high temperature for different times. The behavior of aminoxyl probes, differing by their volatility and their functional groups, was studied. When 4-amino-2,2,6,6-tetramethylpiperidionxy (3) was used as probe, it grafted onto the polymeric chains during curing. Two transitions could then be observed, corresponding to NO^˙ in two environments, which were assigned to the PVC (T_fs, 132–142°C) and to the epoxyphenolic (EP) (T_50G 142–152°C) phases of the varnish. This was confirmed by a separate study of the PVC and EP constituents. Both transition temperatures depended on the extent of curing, suggesting that the PVC phase was plasticized by reactive constituents of the coating. The transition temperatures were also influenced by the extent of penetration of the PVC in the EP phase. Probes which could not graft on the polymer were lost by volatilization during curing. © 1996 John Wiley & Sons, Inc.     

Pyrolytic carbon layers—an electron spin resonance analysis

Chemical vapour infiltration is simulated by deposition of pyrolytic carbon on planar boron nitride substrates and carbon fibers in a hot-wall tubular reactor at about 1100 °C for varied pressure and flow-velocity of methane. The degree of orientation of the deposited graphite-like domains can be monitored via orientation and temperature dependence of the electron spin resonance parameters (g-tensor, linewidth). The electronic structure of the localized defects and conduction electrons is accessible by a quantitative modelling of these parameters. The interaction of the built-in hydrogen atoms with the unpaired electron spins is analysed by electron-proton spin double resonance technique (Overhauser shift)     

Adsorbate interactions of Cu(II) in mesoporous Cu-GaMCM-41 studied by electron spin resonance and electron spin echo modulation

Gallium-containing mesoporous MCM-41 materials (GaMCM-41) were synthesized by adjusting the gel equilibrium between the source gallosilicate mixture and a GaMCM-41 phase using an organic acid. The location of Cu(II) exchanged into the mesoporous GaMCM-41 and its interactions with various adsorbate molecules were investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. The results are compared with those of Cu-AlMCM-41. In a fresh, hydrated Cu-GaMCM-41, Cu(II) is octahedrally coordinated to six water molecules and is located in a cylindrical channel and rotates rapidly at room temperature. Evacuation removes some of these water molecules, leaving the Cu(II) coordinated to fewer water molecules and anchored to oxygens in the channel wall. Dehydration produces one Cu(II) species located on the internal wall of a channel which is accessible to oxygen as evidenced by broadening of its ESR lines by oxygen. Adsorption of water, methanol, ammonia, pyridine, aniline, acetonitrile, benzene and ethylene on dehydrated Cu-GaMCM-41 materials causes changes in the ESR spectra of Cu(II), indicating complex formation with these adsorbates. Cu(II) fully coordinates with a maximum coordination number of polar adsorbates in MCM-41 mesopores. Cu(II) forms a complex with six molecules of methanol as evidenced by an isotropic room temperature ESR signal and ESEM data. Cu(II) forms square planar complexes with four molecules of ammonia, pyridine and aniline based on resolved nitrogen superhyperfine interactions and other ESR parameters. However, Cu(II) forms a complex with six molecules of acetonitrile based on the ESR parameters and ESEM data. Interestingly, Cu(II) does not fully coordinate with nonpolar molecules. Cu(II) interacts directly with only one molecule of benzene, and only part of Cu(II) interacts indirectly with one molecule of ethylene based on ESR and ESEM analyses.     

Study of γ-irradiated lithographic polymers by electron spin resonance and electron nuclear double resonance

The room temperature gamma irradiation degradation of the lithographic polymers, poly(methylmethacrylate) (PMMA), poly(methyl-α-chloroacrylate) (PMCA), poly(methyl-α-fluoroacrylate) (PMFA), and poly(methylacrylonitrile) (PMCN), have been studied by electron spin resonance and electron nuclear double resonance (ENDOR) to assess their molecular degradation processes of relevance to electron beam lithography. Two classes of radicals are found, chain radicals and chain scission radicals. PMMA and PMCA mainly form chain scission radicals consistent with degradation while for PMCN the resolution is poorer, and this is only probable. PMFA forms mainly chain radicals consistent with predominant crosslinking. The total radical yield is greatest in PMCA and PMCN. ENDOR is used to assess the compactness of the radiation degradation region for PMMA and PMCA and hence the potential resolution of the resist; this appears to be about the same for these methacrylate polymers.     

High speed electron spin resonance techniques applied to polymer fracture

Mechanical fracture of nylon 6 produces free radicals as a direct result of bond-breaking; these initial free radicals rapidly decay into secondary free radicals at room temperature. Aromatic nitro-compounds react with the initial, but not the secondary, free radicals. The rate of reaction is sufficiently fast to compete with the usual initial radical decay process, even at room temperature. Considerations involved in applying high speed (microsecond) electron spin resonance techniques are discussed.     

Interpretation of spin concentration measurements from a bituminous coal using in situ electron spin resonance spectroscopy

The spin population in a UK bituminous coal has been measured by in situ ESR as a function of temperature in a conventional sealed tube and in a novel flow cell. It was found that the reproducibility of the results from the closed-tube cell was generally worse, indicating that the contact of evolved volatiles with the char complicates these measurements. Temperature dependence data reinforce this conclusion in that the dependences obtained from the flow cell are much more linear and therefore consistent with Curie Law behavior, than those from a closed tube. Detailed examination of the data suggests that heat-treated coals possess nonzero and variable Weiss constants, which calls into question the blind application of the Curie Law correction term to high-temperature in situ ESR measurements. These results are independent of dilution with silica and so are uncomplicated by sample conductivity effects, which have been invoked to explain some previous anomolous behaviors.