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.     

Enthalpies of pyrolysis and oxidation of Athabasca oil sands

Thermal degradation of Athabasca oil sands, bitumen, and its fractions have been investigated in N₂and in air, at 25–600 °C and at pressures up to 6.9 MPa, using thermogravimetry (TG) and high pressure differential scanning calorimetry (PDSC). These conditions are likely to occur during in-situ recovery of bitumen by underground combustion processes. Two regions of weight loss are detected using both gases. The endothermic low temperature volatilization reactions (150–400 °C) absorbed +26 mJ mg^?1 for oil sand to +2319 mJ mg^?1 for medium oil. The heats of reaction for high-temperature cracking and volatilization reactions (400–550 °C) were similar. The heats of reaction for the low-temperature oxidation reactions (150–375 °C) were ?405 mJ mg^?1 for oil sand to ?30200mJ mg^?1 for medium oil. Values for the high-temperature oxidation reactions (400–550 °C) were slightly higher. Increasing the pressure of nitrogen and air caused an increase in the endothermicity and exothermicity of the respective reactions.     

Melt rheology of blends of semicrystalline polymers. I. Degradation and viscosity of poly(ethylene terephthalate)–polyamide-6,6 mixtures

Melt rheology of poly(ethylene terephthalate)–polyamide-6,6, and their blends was studied between 240°C and 300°C, in capillary and rotational rheometers. The flow curves were determined in the range of rate shear from about 10^?2to 10⁵ (s^?1). The results indicate a considerable degree of compatibility, presence of associations between the two types of macromolecules, and cocrystallization. A new mechanism of flow for the blends has been proposed. The study also considers the kinetics of thermal degradation.     

Measurements of specific heat,thermal conductivity and thermal diffusivity of Utah tar sands

A constant applied heat flux method has been used to measure the specific heat and thermal conductivity of large samples of Utah (North-west Asphalt Ridge) tar sands as a function of temperature. Independent measurements of density allowed for the calculation of thermal diffusivity. Constituent analysis of the tar sand samples also permitted the calculation of bitumen and sand specific heats. Specific heat of the bitumen was found to increase with temperature from 1.85 to 3.9 kJ kg^?1 K^?1 for temperatures between 300 and 480 K. Specific heat of the sand matrix increased only slightly, from 0.85 to 1.0 kJ kg^?1 K^? for the same range of temperature. Corresponding thermal diffusivities for tar sand were found to decrease with temperature, and had a range of 5 · 10^?7–9 · 10^?7 m² s^?1 over the measured temperatures. It was concluded that the latent heat of both bitumen and water have a strong influence on the apparent overall specific heat of tar sand.     

Contribution a l'etude des groupements superficiels des noirs de carbone a l'aide de reactifs gazeux: Evolution de l'acidité superficielle du sphéron 6 au cours de traitements thermiques

The Spheron 6 surface acidity has been investigated by adsorption of ammonia at 70°C and microcalorimetry. The carbon samples are degassed at temperatures up to 950°C. The effects of degassing temperature on the adsorption isotherms of ammonia are shown in Fig. 2. Up to 350°C, the isotherms are characterized by a very slight decrease in the total amount adsorbed. On the contrary, these amounts considerably decrease for higher degassing temperatures. The differential heats of adsorption (Fig. 3), which are initially close to 100 kJ/mole, are shown to decrease with the amount of adsorbed ammonia: the higher the degassing temperature, the greater the decrease. By desorption, the adsorption of ammonia is found partly irreversible. By readsorption it is possible to measure the differential heat of the reversible adsorption and to deduce from it the differential heat of the irreversible adsorption (Fig. 4) as well as the amount irreversibly adsorbed, i.e. chemisorbed.The amounts of chemisorbed ammonia are found to be respectively 0.36 ± 0.01 × 10^?6 mole m² at 150°C and 0.29 ± 0.01 × 10^?6 mole m^?2 at 350°C. With the surface covering the differential heat of chemisorption of ammonia slightly decreases from 105 to 88 kJ. mole^?1.These values suggest that carboxyl groups are responsible for irreversible adsorption of ammonia. This assumption has been checked by various experiments: the irreversible uptake of ammonia lies in the same range as the number of carboxyl surface groups determined by chemical analysis of functional groups (Table 1); the evolving of H₂O during the decomposition of the ammonium salt formed by reacting with ammonia has been observed and is probably correlated with the irreversible uptake of ammonia (Fig. 8); moreover it must be pointed out that irreversible adsorption of ammonia disappears after methylation of sample by diazomethane (Figs. 5 and 6). Then, the amounts of carboxyl groups can be determined by measuring the irreversibly adsorbed ammonia.This method has been applied to the study of the thermal stability of functional groups. Carboxyl groups are shown to be quickly decomposed by heat treatment above 500–600°C (Fig. 8).It appears from our experiments that the oxidation at constant temperature followed by a cooling under nitrogen is unable to regenerate functional groups on the surface of carbon after their removal at 950°C. On the contrary, by an oxidation at decreasing temperature it is possible to regenerate functional groups because they are stabilized by the oxidising atmosphere.The groups thus created behave like those initially present on Spheron 6: particularly the graph of the thermal elimination of carbon dioxide presents two peaks (Table 2, Fig. 12). The amount of regenerated carboxyl groups is found to be 0.25 × 10^?6 instead of 0.36 × 10^?6mole m^?2 on untreated Spheron 6.     

Thermal properties of acetylacetone

The vapour pressure of acetylacetone has been measured over the temperature range 297–398°k. The results are summarised as: Heat capacity measurements have been carried out on the enol form of acetylacetone over the temperature range 80–300° k. An estimate has been made of heat capacity values below 80° k. Entropy, enthalpy and free energy values have been derived and are listed at ten degree intervals. The melting point (254·80°0·05° k) and heat of fusion (144·8°0·5 abs.Jg^?1) of the enol form have been determined. The results have been used in conjunction with previously published data to evaluate the entropies and the heats, entropies and free energies of formation of the keto and enol forms of acetylacetone in the gaseous and liquid phases at 298·16° k.     

Differential scanning calorimetry studies on coal. 2. Hydrogenation of coals

Results of exothermic heats involved during hydrogenation of twenty U.S. raw coals of varying rank at 5 · 6 MPa (gauge) and temperatures up to 570 °C are reported. The heat evolved during hydrogenation up to 570 °C decreases with increase in coal rank. A part of the total heat released during hydrogenation of coals appears to be due to the exothermic reaction between H₂ and surface carbon-oxygen complexes removed during the reaction. The transition temperature, that is the temperature corresponding to the onset of exotherms, is markedly dependent on coal rank. A sharp increase in the transition temperature occurs for coals having a carbon content, on a dry-ash-free basis, in the 75–80% range. Demineralization of coals lower in rank than HVA bituminous decreases the heat of hydrogenation; in the case of higher-rank coals, exothermic heats increase upon demineralization. The presence of pyrite has a beneficial catalytic effect on coal hydrogenation.     

Low-temperature air oxidation of caking coals. 1. Effect on subsequent reactivity of chars produced

The effect of preoxidation of two highly caking coals in the temperature range 120–250 °C on weight loss during pyrolysis in a N₂ atmosphere up to 1000 °C and reactivity of the resultant chars in 0.1 MPa air at 470 °C has been investigated. Preoxidation markedly enhances char reactivity (by a factor of up to 40); the effect on char reactivity is more pronounced for lower levels of preoxidation. For a given level of preoxidation, the oxidation temperature and the presence of water vapour in the air used during preoxidation have essentially no effect on weight loss during pyrolysis and char reactivity. An increase in particle size of the caking coals reduces the rate of preoxidation as well as subsequent char reactivity. Preoxidation of caking coals sharply increases the surface area of the chars produced. Compared to heat treatment in a N₂ atmosphere, pyrolysis in H₂ of either the as-received or preoxidized coal results in a further increase in weight loss and a decrease in subsequent char reactivity.     

Enlargement of the micropores of a caking bituminous coal by controlled oxidation

In a study of the enlargement of pores of coals it has been found that treatment of a bituminous coal (PSOC No. 371, from the Pennsylvania State University Coal Section) with a 5:95 O₂:N₂ stream 4 h at 400 °C increases the surface area as measured by nitrogen adsorption at 77K by a factor of at least 50 to a value 52 m² g^?1. The increase in pore size was accompanied by a 9.7% weight loss. Simultaneously, the area as measured by carbon dioxide at 195K increased from 61 to 136 m² g^?1 and that measured by carbon dioxide at room temperature increased from 125 to 237 m² g^?1. Attempts to enlarge the pores by oxidation with hydrogen peroxide or ozone were unsuccessful. A Pittsburgh coal subject to a small percentage of oxygen in nitrogen or steam at 300 to 400 °C showed a surface area as measured by nitrogen adsorption of less than 1 m² g^?1 both before and after such pretreatment. This same coal with a 5:95 O₂:N₂ stream for 4 h at 450 °C showed a surface area of 110 m² g^?1 measured by nitrogen adsorption at 77K.     

Effect of sintering temperature on the thermal expansion behavior of ZrMgMo3O12p/2024Al composite

A 2024Al metal matrix composite with 10?vol% negative expansion ceramic ZrMgMo₃O₁₂ was fabricated by vacuum hot pressing, and the influence of sintering temperature on the microstructure and thermal expansion coefficient (CTE) of alloys was investigated. Experimental results showed that all ZrMgMo₃O_12p/2024Al composites sintered at 500–530?°C had a similar reticular structure and exhibited different linear expansion coefficients at 40–150?°C and 150–300?°C. The addition of 10?vol% ZrMgMo₃O₁₂ decreased the CTEs of 2024Al by ~ 16% at 40–150?°C and by ~ 7% at 150–300?°C. This addition also increased the hardness of 2024Al by ~ 23%. The density of the composites and the content of Al₂Cu in ZrMgMo₃O_12p/2024Al increased as the sintering temperature increased. The CTEs of the composites decreased, whereas hardness increased. Thermal cycling from 40?°C to 300?°C caused the CTEs of the composites to decrease gradually and reach a stable value after seven cycles. The lowest CTEs of 15.4?×?10^?6 °C^?1 at 40–150?°C and 20.1?×?10^?6 °C^?1 at 150–300?°C were obtained after 10 thermal cycles and were reduced by ~ 32% and ~ 17%, respectively, compared with the CTE of the 2024Al. Among the current reinforcements, ZrMgMo₃O₁₂ negative expansion ceramics showed the highest efficiency to decrease the CTE of Al matrix composites.     

Novel heat resistant methyl‐tri(phenylethynyl)silane resin: Synthesis,characterization and thermal properties

Methyl‐tri(phenylethynyl)silane (MTPES) was successfully synthesized by the reaction of lithium phenylacetylide with methyltrichlorosilane. The structure was characterized by HRMS, FTIR, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, and elementary analysis. Thermal cure process was monitored by DSC, DMA, and FTIR. MTPES was heated to free flowing liquid around 130°C and thermally polymerized at 327–377°C to form thermoset. Thermal and oxidative properties were evaluated by TGA analysis. Thermoset exhibits extremely high heat‐resistance and TGA curve in nitrogen shows the temperature of 5% weight loss (Td₅) of 695°C and total weight loss at 800°C of 7.1%. TGA shows a high Td₅ of 565°C even in air, although the total weight loss at 800°C was 56.1% of the initial weight, much higher than that in nitrogen. The high heat resistance of MTPES was ascribed to crosslinking reaction concerning ethynyl groups. Aging studies performed at elevated temperatures in air on a thermoset showed that MTPES is oxidatively stable to 300°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2488–2492, 2006     

Sorption of P(V), As(V), and Sb(V) Oxyanions on Goethite and Hematite During their Thermal Transformation

Sorption of pentavalent oxyanions P(V), As(V), and Sb(V) was studied on goethite and hematite prepared by its thermal transformation. The surface properties of goethite and products of its thermal modification at different temperatures were studied by BET method, FT-IR, XRD, and DTA-TGA. Amounts of immobilized ions reached their maxima on sorbent prepared at 250°C. Changes of the specific surface area (32.5 m².g^?1 at 150°C, 82.3 m².g^?1 at 250°C and 34.8 m².g^?1 at 350°C) during the thermal transformation at different temperatures were observed. Further analysis confirmed the complete transformation of goethite to hematite at temperatures 200 ? 250°C accompanied with the disappearance of hydroxyl absorption bands at ～800 and ～900 cm^?1 in FT-IR spectrum and significant loss of weight observed on TGA curve. The study of adsorption isoterms revealed that antimony has higher affinity for all studied sorbents.     

Thermal Stability and Mechanical Properties of Organo-Soluble and Processable Polyimides for High-Temperature Materials

A new series of organo-soluble polyimides with pendant groups of methoxy or methyl of azomethine diamine were synthesized through two-step process by chemical imidization. Such polyimides were tested for thermal and mechanical properties. Their thermal stability was studied in terms of temperature at 10% weight loss which ranged between 475 and 498°C with T_g around 240–278°C. Activation energy, enthalpy of the polyimides were calculated and ranged 31.12–43.59?kJmol^?1 and 29.46–41.93?kJmol^?1. Thermal, mechanical, and thermodynamic parameters demonstrated that the resulting polyimides can hold excellent application in the fields of high-performance, advanced composites, and high-temperature microelectronics.     

Adsorption of methane on dry coal at elevated pressure

Methane equilibrium adsorption isotherms were determined on Illinois No.6 (Herrin seam), Oklahoma Hartshorne, Pennsylvania Pittsburgh, and Virginia Pocahontas No.3 United States coal seams, using a volumetric method and an equation of state for methane: the amount of methane adsorbed on crushed and dried coal was measured as a function of pressure. Isotherms were measured at 30 °C for the Illinois coal and at 0, 30 and 50 °C for the others. Most measurements were made to 150 atm pressure, but a few to 240 atm. The data were correlated by the Langmuir and the Polanyi adsorption models. The methane—coal system, uncorrected for adsorbate density, adhered well to the Langmuir model up to 150 atm pressure, but Polanyi behaviour could not be demonstrated satisfactorily, with or without a correction for adsorbate density. Monolayer volumes at 30 °C from the Langmuir equation were 28, 24, 19 and 20cm³ (STP)/g coal respectively for the four coals studied (the range for several investigators was 13 to 39 cm³/g and for the Langmuir constant b 0.03 to 0.23 atm^?1). Isosteric heats of adsorption at zero coverage and 30 °C were 4.2, 2.4 and 5.3 kcal/mol for the Hartshorne, Pittsburgh and Pocahontas coals, which indicate that the adsorption is physical. No effect of particle size on equilibrium adsorption was observed in the U.S. mesh range 6–325.     

Conversion of isopropanol and mixed alcohols to hydrocarbons using HZSM‐5 catalyst in the MixAlco™ process. Part 2: Studies at 5000 kPa (abs)

This study employed HZSM‐5 (SiO₂/Al₂O₃ = 280 mol/mol) to produce hydrocarbons from reagent‐grade isopropanol and mixed alcohols made from lignocellulosic biomass (waste office paper and chicken manure) using the MixAlco? process. All studies were performed at P = 5000 kPa (abs). The experiments were conducted in two sets: (1) vary temperature (300–450°C) at weight hourly space velocity (WHSV) = 1.92 h^?1, and (2) vary WHSV (1.92–11.52 h^?1) at T = 370°C. For isopropanol at higher temperatures, the olefins undergo more cracking reactions to produce smaller molecules and more aromatics. At low temperatures, the molecules have less energy so they do not crack and therefore form larger molecules. At T = 300°C, the carbon distribution is bimodal at C9 and C12, which shows trimerization and tetramerization of propene. At 300°C, propene was the only gas produced, cracking did not occur and therefore preserved high‐molecular‐weight molecules. For mixed alcohols, higher temperatures show significant catalyst deactivation; however, isopropanol did not show any catalyst deactivation. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1707–1715, 2016     

Low‐Temperature Sintering of β‐Spodumene Ceramics Using Li2O–GeO2 as a Sintering Additive

Low‐temperature sintering of β‐spodumene ceramics with low coefficient of thermal expansion (CTE) was attained using Li₂O–GeO₂ sintering additive. Single‐phase β‐spodumene ceramics could be synthesized by heat treatment at 1000°C using highly pure and fine amorphous silica, α‐alumina, and lithium carbonate powders mixture via the solid‐state reaction route. The mixture was calcined at 950°C, finely pulverized, compacted, and finally sintered with or without the sintering additive at 800°C–1400°C for 2 h. The relative density reached 98% for the sample sintered with 3 mass% Li₂O–GeO₂ additive at 1000°C. Its Young's modulus was 167 GPa and flexural strength was 115 MPa. Its CTE (from R.T. to 800°C) was 0.7 × 10^?6 K^?1 and dielectric constant was 6.8 with loss tangent of 0.9% at 5 MHz. These properties were excellent or comparative compared with those previously reported for the samples sintered at around 1300°C–1400°C via melt‐quenching routes. As a result, β‐spodumene ceramics with single phase and sufficient properties were obtained at about 300°C lower sintering temperature by adding Li₂O–GeO₂ sintering additive via the conventional solid‐state reaction route. These results suggest that β‐spodumene ceramics sintered with Li₂O–GeO₂ sintering additive has a potential use as LTCC for multichip modules.     

Dependence of coal liquefaction behaviour on coal characteristics. 5. Data from a continuous flow reactor

A classification of coals in which conversion in batch reactors at 400 °C with tetralin (but no H₂ gas) is one classifying parameter, is shown to be highly significant when the coals are hydrogenated in a 1 kg h^?1 continuous flow reactor at 440 and 455 °C with 20.7 MPa of hydrogen. Regressions of the two sets of data against each other show variances explained of 86.5 and 88%, respectively. The yield of material distillable under standard conditions in a vacuum varies over the range 12–60% of dmmf coal.     

Thermal analysis of poly(phenylene sulfide) polymers. I: Thermal characterization of PPS polymers of different molecular weights

Thermal properties of Fortron®

1 ®Registered trademark of Hoechst Celanese Corporation.

poly(phenylene sulfide) (PPS) polymers of different molecular weights were studied by DSC. Crystallization studies revealed that the ability of these polymers to crystallize decreases with increasing molecular weight. The Avrami equation poorly describes the isothermal crystallization of PPS. Lamellar crystallization was observed for the lowest molecular weight sample. For the other, higher molecular weight polymers the Avrami exponent is always between 2 and 3, suggesting development of distorted spherulites with heterogeneous nucleation. The temperature dependence of the solid and melt heat capacities have been determined. The solid specific heat capacity did not exhibit a molecular weight dependence. The heat capacity increase at the glass transition, T_g, has been calculated to be 28.1 J°C^?1 mole^?1. The equilibrium melting point of PPS has been estimated to be 348.5°C using the Hoffman–Weeks method. The T_g of PPS increases with molecular weight. The T_g of the highest molecular weight evaluated is 92.5°C. A DMA relaxation peak corresponding to the onset of the phenylene ring rotation occurs at ?92°C. Only the highest molecular weight could be quenched to a completely amorphous state.     

Laboratory-scale coal reactivity testing for entrained gasification

A relatively simple and rapid micro-gasification test has been developed for measuring gasification reactivities of carbonaceous materials under conditions which are more or less representative of an entrained gasification process, such as the Shell coal gasification process. Coal particles of < 100 μm are heated within a few seconds to a predetermined temperature level of 1000–2000 °C, which is subsequently maintained. Gasification is carried out with either CO₂ or H₂O. It is shown that gasification reactivity increases with decreasing coal rank. The CO₂ and H₂O gasification reactions of lignite, bituminous coal and fluid petroleum coke are probably controlled by diffusion at temperatures 1300–1400 °C. Below these temperatures, the CO₂ gasification reaction has an activation energy of about 100 kJ mol^?1 for lignite and 220–230 kJ mol^?1 for bituminous coals and fluid petroleum coke. The activation energies for H₂O gasification are about 100 kJ mol^?1 for lignite, 290–360 kJ mol^?1 for bituminous coals and about 200 kJ mol^?1 for fluid petroleum coke. Relative ranking of feedstocks with the micro-gasification test is in general agreement with 6 t/d plant results.     

Processing and properties of new heteroaromatic Schiff-base poly(sulfone-ester)s and their blends

A new interesting class of linear Schiff-base poly(sulfone-ester)s has been synthesized by polycondensation of (E)-1-(4,4′-(4-hydroxy-3-chlorobenzylidene)thiocarbamoylaminophenyl-sulfonylphenyl)-3-(4-hydroxy-3-chlorobenzylidene)thiourea with 2,6-pyridinedicarbonyl chloride/thiophene-2,5-dicarbonyl dichloride. The enhancement of physical properties (thermal stability, glass transition temperature, mechanical strength, molar mass, electrical conductivity, etc.) of polymeric materials while maintaining their processability was the foremost aspiration of this research work. The pyridine or thiophene-based heteroaromatic poly(sulfone-ester)s (PSEs) showed ample solubility in amide solvents and good yield. PSEs possessed high inherent viscosity of 1.79–1.93 dL/g and molar mass 125 × 10³–145 × 10³ g mol^?1. The polymers were thermally stable with 10 % weight loss in the range 538–547 °C and glass transition temperature between 293 and 296 °C. Further aim was to obtain novel miscible nano-blends exhibiting good electrical conductivity and heat stability. For this purpose, PAN doped with dodecylbenzenesulfonic acid (PAN/DBSA) was prepared by in situ doping polymerization, and then blended in solution/melt with PSEs. The resulting high performance materials potentially combined the fine thermal properties and processability of poly(sulfone-ester)s with electrical characteristics of polyaniline. FESEM of melt-blended PSEs/PAN/DBSA showed nano-level homogeneity of the microstructure liable for better electrical conductivity (2.7–3.2 S cm^?1). The azomethine and pyridine moieties introduced in the backbone render these polymers thermally and mechanically stable as well as electrically conducting. The miscible blends, exhibited good heat stability (T ₁₀ 520–527 °C, T _g 281–285 °C) and mechanical strength (55.20–57.18 MPa) compared with reported azomethine/polyaniline-based structures. New processable and high-performance engineering plastics, attractive for aerospace applications, can be fabricated using novel blends.