Thermophysical properties of Devonian shales

A detailed study of the thermophysical properties of Devonian shales from the central and eastern United States has been carried out. Thermal conductivity, thermal diffusivity, specific heat and dielectric constant data are presented. A Michigan shale sample with an oil yield of 28 litres per metric ton (1 t^?1) and a Kentucky shale (oil yield: 52 l t^?1) were selected. The specific heats of these shales are in the range 0.20–0.30 cal gm^?1 °C^?1, and increase with increasing temperature. The thermal conductivity (κ) of the two shale samples are comparable (ca. 1 W m^?1 °C^?1). The κ values show only a weak temperature dependance. The thermal diffusivity (α) of these shales range from 0.3–0.5 × 10^?2 cm² s^?1 and tend to decrease with increasing temperature. The dielectric constants show anomalously high values at temperatures above 200 °C. This effect is indicative of interfacial polarization mechanisms presumably arising from loss of water and onset of pyrolysis of the shale organic matter. Comparison of the trends in thermophysical behaviour of Devonian shales with data obtained previously on Green River oil shales is presented. The importance of thermophysical measurements in on-field applications in oil shale technology is highlighted.     

Kinetics of oil generation from oil shale from Liaoning province of China

The intrinsic kinetics of oil generation from 0.124 dm³ kg^?1 Chinese oil shale were determined by a non-isothermal method. Overall first-order kinetics satisfactorily represented the mechanism of kerogen decomposition. The kinetic parameters were determined as 142.8 kJ mol^?1 and 7.495 × 10⁶ s^?1 for activation energy and pre-exponential factor, respectively.     

Electrical conductivity of Colorado oil shale to 900 °C

Electrical conductivity of oil shale from the Anvil Points Mine, Colorado was measured to temperatures > 900 °C with conductance bridges operating at frequencies from 100 to 100 000 Hz. The conductivity of low, intermediate and high grade oil shales (15,124,233 ml kg^?1, respectively) is dependent on water content up to ≈ 100 °C. At ≈ 120 °C, values of conductivity at ≈ 10^?7 S m^?1 are observed for all grades. A strong, time-dependent, increase in conductivity, beginning at ≈400 °C, marks the loss of light hydrocarbons and the formation of a conductive char. The frequency dependence of conductivity-slightly less than a decade increase in conductivity per decade increase in frequency over the temperature range 100–400 °C-vanishes at temperatures near 500 °C. At 600–800 °C, the conductivity of these oil shales reaches a maximum value which is as much as 10⁸ times larger than the conductivity near 250 °C.     

Composition and kinetics of oil generation from non-isothermal oil shale retorting

Oil shale retorting has been carried out under non-isothermal conditions between 623 and 773 K and at different pressures(78 and 765 kPa). The shale oil is separated into five individual components: polar, weak polar, saturates, aromatics and olefin, using a comprehensive analytical procedure. The effects of retorting pressure and heating rate have been studied. The oil yield under high pressure (765 kPa) is ≈10% less than the oil yield under ambient pressure (78 kPa). Much of this reduced yield can be accounted for by the reduced amount of polar component formed at high pressure. Heating rates of 1.67 × 10^?2, 6.67 × 10^?2and 8.33 × 10^?2Ks^?1 have been used; a higher heating rate causes a delay in the appearance of the oil. A simplified kinetic scheme is proposed which includes the distribution of liquid products and pressure effects. The activation energies and frequency factors of generation reactions for total oil and individual components have been obtained.     

Organic geochemistry of the British Kimmeridge Clay: 3. The occurrence and distribution of acyclic isoprenoid C19 alkenes in Kimmeridge Clay shale oils

The occurrence and distribution of acyclic isoprenoid C19 alkenes (pristenes) in Kimmeridge Clay shale oils has been examined. Pristenes comprise ≈ 9 to 15% of isolated alkene fractions, and ≈ 8% of total shale oil non-aromatic hydrocarbons. They are generally much more abundant than pristane, possibly because only limited hydrogenation of isoprenoid alkenes occurs during pyrolysis. Two pristene isomers are identified (mass spectrometry, retention indices, g.c. co-injection), with prist-2-ene the more abundant in several Kimmeridge shale oils. Prist-2-ene/prist-1-ene ratios show some correlation with sediment oil yield and clay mineral content. Clay-rich low oil yield sediments often give prist-2-ene dominated shale oils, whereas high oil yield sediments show prist-1-ene dominance. Results suggest the conversion of prist-1-ene to prist-2-ene during pyrolysis by a time dependent, thermodynamically favourable double bond rearrangement. Two mechanisms are suggested for the generation of prist-1-ene, the primary pyrolysis product, from C20 units CC bonded to Kimmeridge oil shale kerogen: lt]o li](i) a thermolytic, radical induced tertiary hydrogen abstraction followed by homolytic β CC bond cleavage, or li](ii) in the presence of clay minerals, a clay catalysed carbonium ion route involving Lewis acid tertiary hydrogen abstraction and heterolytic β CC bond fission. Prist-1-ene double bond rearrangement is suggested to occur by a clay-catalysed ionic pathway involving proton-donor site double bond protonation followed by collapse of the resultant tertiary carbonium ion by Lewis base deprotonation. While rearrangement is likely to be retarded in analytical flash pyrolysis, Fischer pyrolysis conditions (and laboratory thermal maturation) allow more time for secondary rearrangement. Where the rate of rearrangement is enhanced by increased clay catalyst concentration, e.g. clay rich Kimmeridge shales, prist-2-ene becomes increasingly prominent in the resultant pyrolysates.     

Kinetics of tetralin extraction of Jordan oil shale

Isothermal kinetic data are obtained for the dissolution of Jordan oil shale in a hydrogen-donating solvent (1,2,3,4-tetrahydronaphthalene) in the temperature range 229–315 °C for untreated (as received mf) shale and 230–360 °C for the decarbonated shales. Preheating time was not accounted for in the treatment. For the untreated shale, the first-order plots have two distinct slopes at the lower temperature. For the higher temperatures, the plots fitted a single first-order expression. The activation energies were 42.6 and 85.6 kJ mol^?1 respectively. The data for the decarbonated shale fit a first-order expression with one low activation energy (E_a = 37.6 kJ mol^?1), suggesting a physical control of the dissolution process. Particle size variation showed a maximum yield at 200 mesh and smaller, although tests using large particles were hampered by settling. Solvent to shale ratios variation showed an optimum at about 180 g shale to 550 ml solvent. No effects of pressure of N₂ and H₂ upon the shale slurry yield were found. A reaction mechanism explaining the kinetic data is postulated.     

Product evolution during rapid pyrolysis of Green River Formation oil shale

The devolatilization of rich (209 cm³ kg⁻¹), rapidly heated (1000 K s⁻¹) Green River Formation, Colorado, oil shale has been studied at temperatures from ≈ 600 to 1100K, under helium (170 kPa) and vacuum. Oil yields decrease with increasing pressure at temperatures above the 800–900 K range. This is attributed to an increased probability of condensed phase cracking reactions involving oil precursors with increased pressure. The fact that escape of the oil from shale particles is vaporization-rate limited is supported by a comparison of the molecular weights of oil collected outside the particle and that left within the particle. The measured nature of particle porosity is consistent with the view that external gas pressure can affect vaporization rates within pores. Elemental and infrared characterization of different molecular weight fractions of oil are presented.     

Intrinsic kinetics of low-temperature oxidation of oil shale kerogen

The kinetics of oxidation of kerogen in the Colorado oil shale were measured using a thermogravimetric analysis technique in a continuously increasing temperature mode. The rate data were analysed based on the assumption that, at the relatively low temperatures at which the kinetics were measured, the oxidation reaction takes place on the surface of solid kerogen and that the decomposition of kerogen is not significant. The oxidation rate was determined to be of first order with respect to oxygen partial pressure. The activation energy of reaction was 11.0 ± 2.3 kJ mol⁻¹, and the pre-exponential factor was (6.8 ± 2.5) × 10⁻⁶ m(kPa · s)⁻¹.     

The specific surfaces of peat and wood

The specific surface areas of various particle size ranges of wood and peat were determined. The methods employed are mercury porosimetry, nitrogen adsorption, and solution isotherms. The results indicate that dye solution isotherms offer an accurate means of surface area measurement, however, the values obtained are dependent on (a) the chemical nature of the solute and adsorbent and (b) the molecular dimensions of the solute. Nitrogen isotherms indicate specific surfaces of (21 × 10³)?(27 × 10³) m² kg^?1 for wood depending on the particle size, while an area of 26.5 × 10³ m² kg^?1 was obtained for peat independent of particle size. Acid dye isotherms yield specific surfaces considerably lower than nitrogen isotherm values; for wood (7.3 × 10³)?(9.6 × 10³) m² kg^?1 and for peat, (5.2 × 10³)?(11.8 × 10³) m² kg^?1. Basic dye studies, using wood, indicate surface areas similar in magnitude to those obtained from nitrogen isotherms. For peat, however, very large apparent surface areas are obtained (～100 × 10³ m² kg^?1) and are attributed to chemical interaction between dye molecules and adsorbent and stacking of dye molecules.     

A pH-controlled fed-batch process for dextransucrase production

A fed-batch culture of Leuconostoc mesenteroides has been operated from an initial volume of 4 dm³ using a sucrose/NaOH solution feed on demand with pH control. An enzyme concentration of greater than 300 DSU cm^?3 was achieved in 15 h. A yield of 0.107 kg cells kg^?1 sucrose feed was determined. The enzyme production was growth associated at 2.67 × 10⁷ DSU kg^?1 cells produced. Growth was shown to be linear and attributed to an unknown conservative trace nutrient limitation associated with the yeast extract.     

Kinetics of oil generation from Colorado oil shale

Isothermal and nonisothermal methods have been used to investigate the kinetics of oil generation during decomposition of 91.7 ml/kg (22 U.S. gal/short ton) Colorado oil shale. The result from the nonisothermal method gives an apparent activation energy of 219.4 kJ/mol and a frequency factor of 2.81 × 10¹³s^?1. Furthermore, the process is found to be first-order to within experimental error. These results compare favourably with isothermal data reported here and in the literature. The results show the reliability and convenience of nonisothermal kinetic experiments in studying oil-shale decomposition reactions. The principal advantages are short-term experiments and the lack of initial heat-up periods. Moreover, nonisothermal experiments more accurately simulate actual conditions of above-ground and in situ oil-shale retorting. These kinetics are ‘effective’ values and can only properly be used to describe the macroscopic oil-production process rather than the complex microchemistry.     

Synthetic Cis-Jasmone Exposure Induces Wheat and Barley Volatiles that Repel the Pest Cereal Leaf Beetle, Oulema melanopus L.

The plant semiochemical cis-jasmone primes/induces plant resistance that deters herbivores and attracts natural enemies. We studied the induction of volatile organic compounds (VOCs) in winter wheat and spring barley after exposure of plants to three synthetic cis-jasmone doses (50 μl of 1, 100, and 1?×?10⁴ ng μl^?1) and durations of exposure (1, 3, and 6 h). Cereal leaf beetle, Oulema melanopus, adult behavioral responses were examined in a Y-tube olfactometer to cis-jasmone induced plant VOC bouquets and to two synthetic blends of VOCs (3 green leaf volatiles (GLVs); 4 terpenes?+?indole). In both cereals, eight VOCs [(Z)-3-hexanal, (Z)-3-hexanol, (Z)-3-hexanyl acetate, (Z)-β-ocimene, linalool, β-caryophyllene, (E)-ß–farnesene, and indole] were induced 100- to 1000-fold after cis-jasmone exposure. The degree of induction in both cereals was usually positively and linearly associated with increasing exposure dose and duration. However, VOC emission rate was only ~2-fold greater from plants exposed to the highest vs. lowest cis-jasmone exposure doses (1?×?10⁴ difference) or durations (6-fold difference). Male and female O. melanopus were deterred by both cereal VOC bouquets after plant exposure to the high cis-jasmone dose (1?×?10⁴ ng μl^?1), while females were also deterred after plant exposure to the low dose (1 ng μl^?1) but attracted to unexposed plant VOC bouquets. Both O. melanopus sexes were repelled by terpene/indole and GLV blends at two concentrations (25 ng?·?min^?1; 125 ng?·?min^?1), but attracted to the lowest dose (1 ng?·?min^?1) of a GLV blend. It is possible that the biologically relevant low cis-jasmone dose has ecological activity and potential for inducing field crop VOCs to deter O. melanopus.     

Investigation of the Thermal Decomposition Kinetics of Chalcopyrite Ore Concentrate usıng Thermogravimetric Data

The kinetics of the thermal decomposition of chalcopyrite concentrate was investigated by means of thermal analysis techniques, Thermogravimetry/Derivative thermogravimetry (TG/DTG) under ambient air conditions in the temperature range of 0–900°C with heating rates of 2, 5, 10, 15, and 20°C min^?1. TG and DTG measurements showed that the thermal behavior of chalcopyrite concentrate shows a two-step decomposition. The decomposition mechanism was confirmed using X-ray diffraction (XRD), Scanning Electron Microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) analyses. Kinetic parameters were determined from the TG and DTG curves for steps I and II by using two model-free (isoconversional) methods—Flyn–Wall–Ozowa (FWO) and Kissinger–Akahira–Sunose (KAS). The kinetic parameters consisting of E_a, A, and g(α) models of the materials were determined. The average activation energies (E_a) obtained from both models for the decomposition of chalcopyrite concentrate were 72.55 and 300.77 kJ mol^?1 and the pre-exponential factors (A) were 15.07 and 29.39 for steps I and II, respectively. The most probable kinetic model for the decomposition of chalcopyrite concentrate is an first-order mechanism, i.e., chemical reaction [g(α) = (?ln(1?α))], and an Avrami–Eroeyev equation mechanism, i.e., nucleation and growth for n = 2 [g(α) = (?ln(1?α)^1/2)], for steps I and II, respectively.     

Development of PLZT dielectrics on base metal foils for embedded capacitors

We have deposited Pb_0.92La_0.08Zr_0.52Ti_0.48O₃ (PLZT) films on nickel and copper substrates to create film-on-foil capacitors that exhibit excellent dielectric properties and superior breakdown strength. Measurements with PLZT films on LaNiO₃-buffered Ni foils yielded the following: relative permittivity of 1300 (at 25 °C) and 1800 (at 150 °C), leakage current density of 6.6 × 10^?9 A/cm² (at 25 °C) and 1.4 × 10^?8 A/cm² (at 150 °C), and mean breakdown field strength ≈2.5 MV/cm. With PLZT deposited directly on Cu foils, we observed dielectric constant ≈1100, dielectric loss (tan δ) ≈0.06, and leakage current density of 7.3 × 10^?9 A/cm² when measured at room temperature.     

Generalized theory of the total fracture surface energy for glassy organic polymers

A model is presented that describes the molecular weight dependence of the total fracture surface energy (γ) on glassy organic polymers from monomeric values (γ ≈ 30 erg/cm²) to viscosity-average molecular weights ($\text{M}\text{?}{}_{\mathrm{v}}$) greater than 10⁶ [γ = 1.4 × 10⁵ erg/cm² for poly(methyl methacrylate) (PMMA); γ ≈ 10⁶ erg/cm² for polystyrene (PS)]. The empirical expressions for PMMA and PS combine the energy contributions from the free surface, the cleavage of covalent bonds, and the viscous flow of molecules by assuming a random molecular weight distribution, the critical chain length necessary to permit viscous flow (x), and the entanglement molecular weight (∈). From cleavage and notched tensile bar tests prepared either by solution polymerization or by radiation degradation of commercial PMMA, the overall structure-property relationship is described.     

Ionic conduction and dielectric properties of yttrium doped LiZr2(PO4)3 obtained by a Pechini-type polymerizable complex route

We report on the ion transport properties of Li_1+xZr_2-xY_x(PO₄)₃ (0.05?≤ x?≤?0.2) NASICON type nanocrystalline compounds prepared through a Pechini-type polymerizable complex method. Structural properties were characterized by means of powder X-ray diffraction, Raman spectroscopy and electron microscopy with selected area electron diffraction. Impedance spectroscopy was utilised to investigate the lithium ion transport properties. Y³⁺ doped LiZr₂(PO₄)₃ compounds showed stabilized rhombohedral structure with enhanced total ionic conductivity at 30?°C from 2.87?×?10^?7 S?cm^?1 to 0.65?×?10^?5 S?cm^?1 for x=0.05 to 0.20 respectively. The activation energies of Li_1+xZr_2-xY_x(PO₄)₃ show a decreasing trend from 0.45?eV to 0.35?eV with increasing x from 0.05 to 0.20. The total conductivity of these compounds is thermally activated, with activation energies and pre-exponential factors following the Meyer-Neldel rule. The tanδ peak position shifts to the high-frequency side with increasing yttrium content. Scaling in AC conductivity spectra shows that the electrical relaxation mechanisms are independent of temperature.     

Direct and High Frequency Alternating Current Conduction Mechanisms in Solution Cast Polyaniline Films

Frequency dependent (ac) and independent (dc) conductivity measurements have been carried out on polyaniline (PANI) films deposited by solution casting technique. Under low electric field (1 × 10³ V/cm) condition, the dc conductivity measured in the temperature range of 173–303 K obeys the three-dimensional variable range hopping (3D VRH) formalism. The Mott parameters such as localization length (α^?1 ≈ 7 Å), density of states [N(E _F ) = 1.04 × 10¹⁹ states/eV cm³], hopping range (R _hop = 60 Å) and hopping energy (W _hop = 0.38 eV) are computed. The ac conductivity measured in the frequency range 10 kHz–5 MHz and in the temperature range 150–380 K follow a power-law dependence σ _ac ～ ω ^s, typical for charge transport by hopping or tunnelling processes. Therefore, the experimental results are analyzed with reference to various theoretical models based on quantum-mechanical tunnelling and classical hopping over barriers. The observed minimum in the temperature dependence of the frequency exponent s strongly suggests that tunnelling of large polarons is the dominant transport process. The polaron radius (r _p ≈ 25 Å) and barrier height for infinite site separation (W _HO ≈ 0.22 eV) are evaluated. The density of states [N(E _F)] and tunnelling distances (R _ω ) are estimated and discussed in terms of frequency and temperature.     

Effect of PBMA on PVC‐based polymer blend electrolytes

Poly(vinyl chloride) (PVC)—poly(butyl methacrylate) (PBMA) blended polymer electrolytes with lithium perchlorate (LiClO₄) as the complexing salts are prepared by solution casting technique. The addition of PBMA into PVC matrix is found to induce considerable changes in physical and electrical properties of the polymer electrolytes. Addition of PBMA into PVC matrix is found to increase the conductivity by two orders of magnitude (1.108 × 10^?5 S cm^?1) when compared with that of the pristine PVC polymer electrolyte (10^?7 S cm^?1). Structural, thermal, mechanical, morphological, and polymer–salt interactions are ascertained from X‐ray diffraction (XRD), thermogravimetry/differential thermal analysis (TG/DTA), mechanical analysis, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) respectively. A thermal stability upto 250 °C is asserted from the TG/DTA analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44939.     

Ni0.4Co x Cd0.6 − x Fe2O4 ferrites as prepared by autocombustion synthesis

Ni_0.4Co _x Cd_0.6?x Fe₂O₄ ferrites (x = 0.0, 0.2, 0.4, and 0.6) were prepared by autocombustion synthesis and characterized by XRD, SEM, and other physical methods. XRD reveals the formation of spinel structure without any impurity phase. With increasing x, the lattice parameter was found to decrease from 8.60 to 8.37 Å. The FTIR spectra show the presence of tetrahedral site (at 571.12 cm^?1) and octahedral site (at 407.07 cm^?1). SEM images indicated the formation of agglomerated grains with a size of about 4.3 μm. The resistivity of the ferrites was found to decrease from 24.53 to 10.02 × 10⁸ Ω cm while the drift mobility to increase from 2.30 to 4.41 × 10⁸ cm² V^?1 s^?1 with increasing x.