Carbonylation studies with Illinois No. 6 bituminous coal

Sodium metal and carbon dioxide were used to carbonylate Illinois No. 6 coal in a 1 l, high-pressure, autoclave in anhydrous tetrahydrofuran from 150 to 350 °C. Solubility of the reaction products in tetrahydrofuran and water, and the sodium uptake in the insoluble residue were determined. The reduction and subsequent carbonylation of coal produced a limited amount of solubility in these solvents, and the uptake of sodium in the insoluble residue reached a maximum of 6.29% at 250 °C with no carbon dioxide added. This corresponded to a ratio of sodium atoms per 1000 carbon atoms of 62.9, a 69-fold increase over the unreacted dried coal. Total acidity and carboxyl group content were calculated for the insoluble residues and unreacted bituminous coal. The per cent increase of carboxyl groups reached a maximum of 1.37 meq g^?1 at 2000 °C which represents a 174% increase over the unreacted coal.     

Changes in coal composition during air oxidation at 200–250 °C

Air oxidation of two bituminous coals and a lignite was carried out in a fluidized bed reactor at 200–250 °C. The gaseous products were analysed by gas chromatography and solid samples were titrated to determine carboxylic and total acidity and were subjected to ¹³C n.m.r. spectrometry to determine the fraction of aromatic carbon. Elemental composition, heating value and ash content were also determined. During the first few hours oxidation-induced devolatilization proceeded simultaneously with oxidation. Oxidation of the high volatile bituminous coal for 12 h at 200 °C raised the carboxylic groups from 0.37 to 2.1 meq g⁻¹ and the total acidity from 1.5 to 5.3 meq g⁻¹. The acidic groups seem to be largely distinct from oxygenated groups that are precursors to CO and CO₂ products. Oxidation of the same coal at 200 °C consumed aromatic as well as aliphatic carbon at relative amounts 1:3 to 1:4.     

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.     

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.     

Poly(arylene ether)s carrying pendant (3‐sulfonated) phenylsulfonyl groups

A series of poly(arylene ether)s with biphenyl units and pendant sulfonated phenylsulfonyl groups was prepared via nucleophilic aromatic substitution reactions of varying ratios of 3,5‐difluoro‐3′‐sulfonated diphenylsulfone and 4,4′‐difluorodiphenylsulfone with 4,4′‐biphenol. As such, the sulfonic acid moieties reside in the meta position of a pendant, electron‐poor phenylsulfonyl group. Mechanically robust proton‐exchange membranes with ion‐exchange capacities (IEC) ranging from 0.91 to 2.05 meq g^?1 were cast from dimethylacetamide. The thermal stability of the membranes was evaluated via thermogravimetric analysis and the 5% weight losses were found to be in excess of 330 °C in air. The glass transition temperatures were determined, via differential scanning calorimetry, to range from a low of 148 to a high of 209 °C at IEC values of 0.91 and 1.79 meq g^?1, respectively. The copolymer membranes reached proton conductivities as high as 142 mS cm^?1 under 100% relative humidity, with relatively low water uptake values (8–32 wt%). Copyright © 2012 Society of Chemical Industry     

A cation exchange resin from poly(N-vinyl carbazole)

Poly(N-vinyl carbazole) was sulfonated with different sulfonating agents and ion exchange capacities of the resins produced were evaluated. A maximum capacity of 4.5 meq · g^?1 of dry resin was realized when sulfonation was done with 98.8% H₂SO⁴ at 30°C for 10 h. The pH titration curves reveal the nature of a strong monofunctional cation exchanger with a pK value of 2.2. The resin exhibits a moderate rate of exchange with NaCl and is thermally stable up to ca. 250°C.     

Kinetics and thermodynamics of hydrolytic depolymerization of poly(ethylene terephthalate) at high pressure and temperature

Hydrolytic depolymerization of PET (polyethylene terephthalate) waste in excess of water was studied using a 0.5‐L stirred high‐pressure autoclave at temperatures of 100, 150, 200, and 250°C and at 200, 300, 400, 500, 700, and 800 psi (pounds per square inch) pressure. Velocity constants of hydrolysis were calculated from the experimental data obtained. Maximum depolymerization (91.38%) of PET into monomer was obtained at 250°C and 800 psi. pressure. However, the maximum rate of reaction was recorded at 200°C and 500 psi temperature and pressure, respectively. The energy of activation and frequency factor were calculated, as 64.13 KJ/g mol and 7.336 × 10⁴ min^?1, respectively, for higher pressure and temperature conditions. It was also reported that the hydrolytic depolymerization is first order with the velocity constant 1.773 × 10^?2 min^?1 at 250°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3305–3309, 2003     

Effect of pyrite and pyrrhotite on free radical formation in coal

The effects of pyrite (FeS₂) and pyrrhotite (Fe₇S₈) on free radical formation in a coal sample (81% carbon content) have been investigated by electron spin resonance (e.s.r.) spectroscopy. Changes in the e.s.r. parameters (spin concentration g^-1, n, linewidth ΔH and g-value) were monitored in samples of coal, coal+8% FeS₂ and coal+8% Fe₇S₈, as these samples were heated in vacuum or in hydrogen from room temperature to 500 °C, in steps of 50 °C for a residence time of 30 min at each temperature. In vacuum heating, changes in n begin to occur at 400 °C, 350 °C and 300 °C respectively for coal, coal+8%Fe₇S₈ and coal+8% FeS₂ samples whereas in H₂, the corresponding temperatures are 250 °C, 200 °C and 150 °C. Changes in ΔH and g were also observed at these temperatures. The maximum increase in n occured for coal+8% FeS₂ samples whereas the minimum increase was observed for the pure coal sample. It is argued that enhancement in n is due to two mechanisms: the pyrite to pyrrhotite conversion and the presence of pyrrhotite itself. The detailed nature of the catalytic activity of pyrrhotite is not known.     

Gasification of coals treated with non-aqueous solvents. 1. Liquid ammonia treatment of a bituminous coal

A Japanese bituminous coal was treated with liquid ammonia at temperatures up to 120 °C. Extract was separated from the treated coal by washing with benzene-ethanol mixture. The amount of extract was about 2% in a single treatment at 120 °C and some additional extract was obtained by successive treatments. Particles of the residue had cracks and showed an increase in surface area. The ammonia-treated coal was found highly reactive toward gasification with hydrogen at high temperature when catalysed by nickel.     

Partially Fluorinated Multiblock Poly(arylene ether sulfone) Membranes for Fuel Cell Applications

Sulfonated poly(arylene ether sulfone) (SPAES‐F series) membranes, which are partially fluorinated multiblock polymers containing Bisphenol 6F (6F‐BPA), are synthesized. The membranes exhibit less water uptake and higher ion conductivity at similar ion exchange capacity (IEC) values compared to previous SPAES membranes containing identical hydrophilic blocks. This is attributed to the presence of 6F‐BPA in the hydrophobic block, which enhances hydrophobicity and promotes phase separation, as observed through transmission electron microscopy analysis. F4 (IEC = 2.4 meq g^?1) shows superior ion conductivity than Nafion NRE212 membrane irrespective of the humidity level. Furthermore, the SPAES electrolyte membrane of 1.5 meq g^?1 produces better performance than NRE212, yielding a current density of 488 mA cm^?2 at 80 °C, 80% RH, and 0.6 V. In 50% RH at 80 °C, SPAES with 1.5 meq g^?1 exhibits a cell resistance and fuel cell performance comparable to those of NRE212; clearly, regulating hydrophobicity and hydrophilicity is crucial for enhanced performance.     

Adsorption of cadmium and zinc from aqueous solution on natural and activated bentonite

The adsorption of cadmium and zinc ions on natural bentonite heat-treated at 110°C or at 200°C and on bentonite acid-treated with H₂SO₄ (concentrations: 0·5 mol dm^?3 and 2·5 mol dm^?3), from aqueous solution at 30°C has been studied. The adsorption isotherms corresponding to cadmium and zinc may be classified respectively as H and L types of the Giles classification which suggests the samples have respectively a high and a medium affinity for cadmium and zinc ions. The experimental data points have been fitted to the Langmuir equation in order to calcualte the adsorption capacities (X_m) and the apparent equilibrium constants (K_a) of the samples; X_m and K_a values range respectively for 4·11 mg g^?1 and 1·90 dm³ g^?1 for the sample acid-treated with 2·5 mol dm^?3 H₂SO₄ [(B)-A(2·5)] up to 16·50 mg g^?1 and 30·67 dm³ g^?1 for the natural sample heat-treated at 200°C [B-N-200], for the adsorption process of cadmium, and from 2·39 mg g^?1 and 0·07 dm³ g^?1, also for B-A(2·5), up to 4·54 mg g^?1 and 0·45 dm³ g^?1 [B-N-200], for the adsorption process of zinc. X_m and K_a values for the heat-treated natural samples were higher than those corresponding to the acid-treated ones. The removal efficiency (R) has also been calculated for every sample; R values ranging respectively from 65·9% and 8·2% [B-A(2·5)] up to 100% and 19·9% [B-N-200], for adsorption of cadmium and zinc.     

Effect of preheating on chemical structure and infrared spectra of Yanzhou coal

The results of thermosolvolysis experiments performed on a high volatile bituminous coal from Yanzhou, China are described. The coal was preheated in a vacuum at temperatures between 250 and 400 °C, after which the soluble materials were extracted with chloroform, l.r. spectra of the preheated coal, the chloroform extract, and the residue after extraction were measured and compared. The extraction yield passed through a maximum for a preheating temperature near the plastic softening point of the coal. As the preheating temperature was increased, the aromaticity of the coal and its residue after extraction increased markedly. The aromaticity of the extract appeared to increase slightly and the methylene-methyl ratio of the extract dropped significantly near the softening temperature. The ester content of the extract was reduced to almost zero on preheating the coal, presumably because of decarboxylation during preheating.     

Investigation of equilibrium and kinetic parameters of methylene blue adsorption onto MCM-41

Mesoporous MCM-41 was synthesized at room temperature using tetraethoxysilane (TEOS) with cetyltrimethylammonium bromide (CTAB) and employed as an effective adsorbent for the adsorption of methylene blue dye from aqueous solution. The as-synthesized MCM-41 was calcined at 250 and 550°C to study the relation between the surface area and pore volume with surfactant removal. The synthesized MCM-41 was characterized using thermo gravimetric analysis (TGA), X-ray diffraction (XRD) patterns, nitrogen adsorption/desorption isotherms and Fourier transform infrared (FT-IR) spectroscopy. The MCM-41 calcined at 550°C showed higher surface area (1,059 m² g^?1) with pore volume of 0.89 ml g^?1 and was used for the investigation of adsorption isotherms and kinetics. The experimental results indicated that the Freundlich and Redlich-Peterson models expressed the adsorption isotherm better than the Langmuir model. In addition, the influence of temperature and pH on adsorption was also investigated. The decrease in temperature or the increase in pH enhanced the adsorption of dye onto MCM-41. A maximum adsorption capacity of 1.5×10^?4 mol g^?1 was obtained at 30°C. The kinetic studies showed that the adsorption of dye on MCM-41 follows the pseudo-second-order kinetics.     

Combustion behaviour of bituminous and anthracite coal char between 425 and 900 °C

The combustion behaviour of bituminous and anthracite coal char has been studied for temperatures ranging from 425 to 900 °C. The combustion reaction was carried out in a thermogravimetric analyser at 1 atm. A wide range of oxygen partial pressures, from 5×10^?4 to 10^?1 MPa was used. For bituminous char, below 600 °C the intrinsic reaction order and activation energy are 0.75 and 29.0 kcal gmol^?1, respectively, while above 650 °C, the intrinsic reaction order and activation energy are 0.3 and 45.2 kcal gmol^?1. For anthracite char, below 600 °C the intrinsic reaction order and activation energy are 0.9 and 32.8 kcal gmol^?1, while above 650 °C, the intrinsic reaction order and activation energy are 0.3 and 43.6 kcal gmol^?1. The changes in the reaction order and activation energy in the temperature ranges above and below 600 °C imply that the dominant reaction mechanism is different for these two temperature ranges.     

Hyperbranched Acrylate Copolymer via Initiator‐Fragment Incorporation Radical Copolymerization of Divinylbenzene and Ethyl Acrylate: Synthesis,Characterization, Hydrolysis,Dye‐Solubilization,Ag Particle‐Stabilization,and Porous Film Formation

Summary: Soluble hyperbranched acrylate copolymers were prepared by the copolymerization of divinylbenzene (0.10 mol · L^?1) and ethyl acrylate (0.50 mol · L^?1) using dimethyl 2,2′‐azoisobutyrate of high concentrations (0.30–0.50 mol · L^?1) as initiator at 70 and 80 °C in benzene. The copolymer formed at 80 °C for 1 h showed the weight‐average molecular weight of 2.5 × 10⁵, the small radius of gyration of 10 nm, the low second virial coefficient of 5.7 × l0^?7 mL · g^?2 as shown by the MALLS measurements at 25 °C in tetrahydrofuran, and also the very low intrinsic viscosity of 0.10 dL · g^?1 at 30 °C in benzene. The hyperbranched copolymer exhibited an upper critical solution temperature (35 °C on cooling) in an acetone‐water (60:11 v/v). The copolymer showed an ability to encapsulate and transfer Rhodamine 6G as a dye probe and could stabilize Ag nanoparticles. The porous film was prepared by simply casting an acetone solution of the hyperbranched copolymer on a cover glass. The copolymer molecules radially arranged on the surface layer of the spherical pores as observed by the polarized optical microscope. The hyperbranched acrylate copolymer was hydrolyzed by KOH to yield poly(carboxylic acid).

Optical microscope image (crossed polarizers) of a porous film from copolymer solution in acetone.     

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.     

Effects of culture temperature on the production of bioactive polysaccharides by Agaricus blazei in batch cultures

Effects of culture temperature ranging from 20 to 34 °C on cell growth, polysaccharide biosynthesis and the bioactivity of polysaccharides of Agaricus blazei were evaluated via eight batch cultures in steps of 2 °C in a stirred tank bioreactor. Results indicated that the optimal temperature for the biomass was 28 °C with a cell yield of 780 mg g^?1, while that for polysaccharide formation was 30 °C with a product yield of 230 mg g^?1. Both the β‐glucan content and average molecular weight of the polysaccharides from different temperature‐controlled cultures were closely correlated with their tumour necrosis factor‐α (TNF‐α) release capability on macrophage cells. The polysaccharides from the low temperature range (20–24 °C) not only had higher relative content of β‐glucan and average molecular weight but also exhibited higher bioactivity compared with those from the high temperature range (30–34 °C). The optimal temperature for the production of bioactive polysaccharides of A. blazei was 24 °C, at which their relatively high molecular weight, β‐glucan content and TNF‐α release capability on macrophage cells were 1650 kDa, 188 mg g^?1 and 1560 pg per 5 × 10⁴ cells respectively. Copyright © 2007 Society of Chemical Industry     

A preliminary account of char structures produced from Liddell vitrinite pyrolysed at various heating rates

Liddell-seam vitrinite particles were heated to 1000 °C in nitrogen at uniform rates ranging from 10^?1 °C s^?1 to 10⁴ °C s^?1. Little melting or swelling was observed when the particles were heated at 10^?1 °C s^?1 even though the vitrinite is from a coking coal of high-volatile bituminous rank. Particle size (100 μm) and loose packing were probably major influences on the plasticity. Vitrinite particles heated at rates faster than 10^?1 °C s^?1 showed an increase in plasticity with heating rate but the effects related to plasticity and volatile evolution appeared to be approaching a limit. Simple cenospheres (primary vesicles) were formed and preserved at a heating rate of 1 °C s^?1. At a heating rate of 10 °C s^?1 secondary vesicles were produced and preserved in the walls of the primary vesicles. At faster heating rates only secondary and tertiary vesicles were preserved. At a heating rate of 10⁴ °C s^?1 the vesicles preserved were very small.     

Production of low ash coal by thermal extraction with <Emphasis Type="Italic">N</Emphasis>-methyl-2-pyrrolidinone

Present study was conducted for the purpose of producing low ash coal from LRC (low rank coals) such as lignite and sub-bituminous coal through thermal extraction using polar solvent. Extraction from bituminous coal was also investigated for comparison. NMP as a polar solvent was used. The ratio of coal to solvent was adjusted as 1: 10. Experimental conditions were established which include the extraction temperature of 200–430 °C, initial applied pressure of 1–20 bar and extraction time of 0.5–2 hr were used. Extraction yield and ash content of extracted and residual coal were measured. The extraction yield increased with the increase of extraction temperature, and the ash content of extracted coal decreased below 0.4% at 400 °C from the raw coal samples that have the ash contents of 4–6%. According to the analysis of experiments results, fixed carbon and calorific value increased, and H/C and O/C decreased.     

Heat of wetting of a bituminous coal

Heat of wetting with water has been measured for samples of an Australian low-rank bituminous coal with different initial moisture contents. Although dry coal showed a substantial heat of wetting (≈6 kJ kg^?1), values decreased rapidly with increasing moisture content and it is calculated that for a normal moist coal (65% relative humidity) heat of wetting could cause a temperature rise of only ≈2 °C, which would be unlikely to contribute significantly to self-heating in stored coal.