Upgrading of low rank coal with solvent

In this study, thermal upgrading of low-rank coal with solvent at 380–440 °C under an initial nitrogen pressure of 2 MPa was studied as a possible method for producing clean solid fuel with a high heating value and less spontaneous ignition behavior. Upgrading of Buckskin coal (USA, subbituminous coal) in the presence of t-decalin (non hydrogen-donor solvent) at 440 °C gave 11.4 wt.% of gas, 5.3 wt.% of oil and 74.1 wt.% of upgraded solid product with a small amount of water. The gaseous product consisted mainly of carbon dioxide (67 wt.%), methane, carbon monoxide, hydrogen and a trace of C₂ and C₃ hydrocarbon gases. The oil product from coal contained BTX, phenol, and their alkyl-derivatives. The heating value of the upgraded solid product from the Buckskin coal increased to 31.0 MJ/kg in dry base as compared to the heating value of wet base of the untreated raw coal, which was 19.3 MJ/kg. Spontaneous ignition behavior was greatly reduced by the upgrading. The effect of catalyst and additives on the upgrading was investigated in terms of product distribution and the quality of the solid product. Taiheiyo (Japan, subbituminous) and Yallourn (Australia, brown) coals were also studied.     

Thermodynamic and Kinetic Analyses of the Hydrogenation of Coal from the Mamytskoe Deposit

The kinetic and thermodynamic parameters (the equilibrium degree of reaction, the rates of forward and reverse reactions, the equilibrium constant, the activation energies of forward and reverse reactions, the Gibbs free energy, and the heat effect and entropy of the process) of the hydrogenation of coal from the Mamytskoe deposit of (Republic Kazakhstan) at 380–440°C were calculated with the use of equilibrium kinetic analysis (EKA). It was established that the rate of forward reaction increased whereas the rate of reverse reaction decreased with temperature. The application of the kinetic–thermodynamic model obtained to the hydrogenation of coal from the Mamytskoe deposit facilitated the understanding of the chemical conversion of the organic matter of coal.     

Analysis of oil obtained from mild hydrogenation of coal. 1. structural analysis of fractionated oil

Shin Yubari coal (86.7% C) was mildly hydrogenated repeatedly at 340–385°C under an initial hydrogen pressure of 10 MPa for 1 h, using Adkins catalyst. The product was extracted with benzene at 200°C and the residue was again reacted. Finally, benzene solubles were extracted with n-hexane, and n-hexane insolubles were hydrogenated under similar conditions at 380°C; the product was then extracted with n-hexane. The yield of total n-hexane solubles was 52.5%. Acid and base were extracted with sulfuric acid and NaOH, and the neutral part (50.2%) was chromatographed using an alumina column with 2.5% water and separated into 12 fractions. UV and IR spectra, ultimate analysis and ¹H-NMR spectra were obtained for each fraction and a structural analysis was carried out to obtain an image of each average structure. The aromatic ring numbers estimated from UV spectra and from structural analysis for each fractions agree well with each other; the average value was 3.2.     

Coal liquefaction using indene-tetralin and indene-decalin mixtures as solvent

Indene-tetralin and indene-decalin mixtures were used as the solvent for coal liquefaction. The effect of mixing on conversion for Yallourn coal was observed under nitrogen pressure at 400 and 440 °C. Conversion to benzene-soluble material in an indene-decalin mixture (50:50, wt) at 440 °C for 1 h was 73.0% and was only 9% lower than that in 100% tetralin. The reaction of indene with tetralin or decalin may provide the active species for coal dissolution. Simultaneously, coal radicals may be scavenged by indene.     

The effect of extraction condition on ‘HyperCoal’ production (1)—under room-temperature filtration

In order to produce ashless coal (HyperCoal) in a high yield, extractions with several organic solvents—tetralin, 1-methylnaphthalene, dimethylnaphthalene and light cycle oil (LCO) at 200–380 °C were conducted for various ranks of coals, and subsequent solid/solution separation was done at room temperature. LCO was found to be a useful, cost-effective solvent, since it gave similar extraction yields to three other reagent solvents. The extraction yield for Illinois No. 6 coal gradually increased over 200 °C, and a significant increase in extraction yield was observed from 350 to 360 °C. We succeeded in producing ashless coal with less than 0.1% in ash content for seven of nine coals used in this study.     

Hydrorefining of syncrude to diesel oil

Synthetic crude derived from hydrogenation of coal is difficult to refine for the production of quality grade middle distillates because of its highly aromatic nature and high concentration of heteroatoms. A synthetic crude produced in the Central Fuel Research Institute's (CFRI's) coal hydrogenation pilot unit has been hydrorefined in two stages utilising CoMoAl₂O₃ catalyst in the prehydrogenation stage and MoS₂ catalyst in the subsequent second stage. The yield of HSD (above 200°C) from syncrude fraction (170–340°C) was 66% while the yield of naphtha (below 200°C) was 25%.     

Treatment of coal and formic acid mixtures with water at supercritical parameters

The treatment of coals of various degrees of metamorphism in supercritical water (SCW) over the temperature region 380–800°C was studied. The possibility of obtaining strong agglomerates from the powders of long-flame and oxidized fat noncoking coals by treatment in SCW was demonstrated. The strength of agglomerates was commensurable with the strength of lump coal.     

Two-stage hydrodenitrogenation of heavy distillate in a coal liquid

Successive two-stage hydrodenitrogenation using a commercial NiMo catalyst was applied to a heavy distillate of a coal liquid to achieve a high level of denitogenation. A successive hydrotreatment in 1-methylnaphthalene, at 390 °C for 2 h and at 440 °C for 2 h under hydrogen pressure of 12 MPa, removed 83% (overall) nitrogen from the distillate, while a single reaction at 420 °C for 3 h under 23 MPa removed only 34%. Addition of catalyst prior to the second stage reaction, or a four-ring aromatic such as pyrene or fluoranthrene as a component of the reaction solvent (20 wt%) increased markedly the removal of nitrogen in the two stage hydrotreatment. Based on preliminary analyses of the products, a combination of extensive hydrogenation in the first stage and effective CN bond cleavage in the second is suggested for the course of the effective denitrogenation. Suppression of catalyst deactivation, by proper choice of solvent may be another reason. The hydrogen pressure required for denitrogenation can be reduced in a two-stage process.     

γ-丁内酯催化合成聚乙烯吡咯烷酮(PVP)单体的研究

以 γ-丁内酯为原料 ,经过乙醇胺的胺解得到羟乙基吡咯烷酮 (NHP) ,研制筛选出 NHP脱水反应较理想的催化剂 ,其组成为 K1Si50 B0 .4 ,由 NHP的脱水反应合成了 PVP单体。通过实验得到最佳 NHP脱水反应最佳条件为 :催化剂用量 9～ 1 1 m L,反应温度 380～ 390°C,真空度 90～ 95k Pa进料空速 1 0 0～ 1 50 m L/g·h。使 NHP脱水反应转化率达 70 %以上 ,选择性达 90 %以上。     

A highly selective synthesis of pyrazine from ethylenediamine on copper oxide/copper chromite catalysts

Ethylenediamine (ED) vapor on passing over a series of copper oxide/copper chromite catalysts in the temperature range of 340–440 °C yielded pyrazine with a very high selectivity (98–100%), the reaction proceeds by intermolecular deamination and cyclization of ED to form piperazine, which undergoes subsequent dehydrogenation to form pyrazine. Reaction parameters like effect of temperature, contact time, reactant feed ratio and time on stream were found to have profound effect on the reactant conversion as well as the product selectivity.     

Degradation of polystyrene in supercritical n-Hexane

Degradation of polystyrene was carried out in supercritical n-hexane under reaction temperature ranging from 330 °C to 390 °C, pressure ranging from 30 bar to 70 bar and reaction duration of 90 min. The conversion of polystyrene increased with rising temperature and pressure. The degradation performance was influenced by the temperature rather than applied pressure. Polystyrene rapidly degraded in 30 min after reaching a prescribed temperature ranging from 350 °C to 390 °C. At a prescribed temperature of 390 °C, the degree of degradation was higher than 90%. The degradation reaction was examined experimentally at a relatively low temperature of 330 °C. The degradation of polystyrene by using supercritical n-hexane has been found to be more effective compared to general pyrolysis (thermal degradation). Among the selectivity of liquid products, that of a single aromatic ring group like styrene at 390 °C increased up to 65% in 90 min. It was found from the analysis by a gel permeation Chromatograph (GPC), that high molecular-weight compounds decreased but oligomers increased with rising temperature.     

Accelerated controlled radical polymerization of methacrylates

BACKGROUND: Nitroxide adducts 1,1‐ditertbutyl‐1‐(1‐methyl‐1‐cyanoethoxy)‐amine (AIBN/DBN), 1,1‐ditertbutyl‐1‐(benzoylperoxy)‐amine (BPO/DBN) and 2,2,6,6,‐tetramethyl‐4‐oxo‐1‐(1‐methyl‐1‐cyanoethoxy)‐piperidine (AIBN/4‐OXO‐TEMPO) were prepared and evaluated as stabilized unimolecular initiators for controlled radical polymerization of methacrylate monomers using sulfuric acid as an accelerating additive. Their effectiveness was evaluated from polymerization rates, molecular weight control and dispersity (D) of the polymers. Thermal stabilities of the polymers were also examined. The monomers used were methyl methacrylate, triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (EBPADMA). RESULTS: Polymerization was accomplished at 70 and 130 °C in 5 min to 144 h. The value of D of poly(methyl methacrylate) (PMMA) was 1.05–1.22. The glass transition temperature (T_g) for PMMA was 122–127 °C. The activity of the chain ends was established by chain extension and controlled polymerization was established by plotting M_n versus monomer conversion. First‐order kinetics in monomer consumption was established and an electron paramagnetic resonance study was conducted. Decomposition temperature (T_d) for PMMA was 360–380 °C, for poly(TEGDMA) was 300–380 °C and for poly(EBPADMA) was 360–440 °C. Photoinitiation without additive yielded no polymer. Thermal initiation by AIBN/4‐OXO‐TEMPO was the fastest. CONCLUSIONS: The initiators are applicable in low‐temperature additive‐enhanced controlled polymerization of methacylates and dimethacrylates, producing polymers with excellent attributes and a low value of D. Copyright © 2008 Society of Chemical Industry     

Influence of fibre content on the strength of carbon fibre reinforced HfC/SiC composites up to 2100 °C

The influence of carbon fibre content on the mechanical behaviour of HfC/SiC composites was investigated up to 2100 °C for specimens containing 40 or 55 vol% fibres. Silicon carbide was added as a sintering aid during hot pressing. Increasing the fibre content made infiltration more difficult, which resulted in higher porosity in the specimen with 55 vol% fibres. The room temperature flexural strength ranged from 340 to 380 MPa, and it increased to more than 400 MPa at 1800 °C due to stress relaxation. Increasing temperature was accompanied by a decrease in the slope of the load-displacement curve, indicating a decrease in elastic modulus, but plastic deformation was not observed below 2100 °C. At 2100 °C, the specimen containing a higher fibre content underwent significant deformation due to low interfacial strength between the fibre plies, retaining a strength at the proportional limit of 290 MPa and an ultimate strength of 520 MPa.     

Thermogravimetry-combustion characteristics of high-carbon fluidized-bed cyclone ashes

Thermogravimetry combustion characteristics are obtained for three samples of high-carbon cyclone ash, the samples received from an R & D fluidized bed combustion unit utilizing Ohio No. 6 bituminous coal with limestone. Non-isothermal TG combustion in air (at a programmed heating rate of 2 °C min^?1) for a cyclone ash (25.0 wt% carbon) indicates two chemically different combustibles, ≈82 wt% of higher reactivity with maximum weight-loss rate at 490 °C and 18 wt% correspondingly of lower reactivity at 645 °C. Isothermal TG combustion of the same ash at 700 °C and at 850 °C also indicates the presence of the two types of combustibles and gives an E_a of about 150 kJ mol^?1 for combustion of the lower reactivity type. Additionally, each of two other samples of cyclone ash (20.1 and 6.9 wt% carbon) contains two types of combustibles as evidenced by TG combustions. Non-isothermal TG combustion of feed coal, a single maximum weight loss at 440 °C, shows the coal has greater reactivity than each of the three ashes. A combustion chemistry explanation for two types of combustibles is suggested by the postulated reactivity order for the organic matter or maceral groups of coal, i.e., vitrinite ? exinite ? inertinite.     

Effects of Annealing Temperature on the Structure and Capacitive Performance of Nanoscale Ti/IrO2–ZrO2 Electrodes

Electrodes consisting of coating of the Iridium oxide–Zirconium oxide (70%IrO₂–30%ZrO₂) binary oxide were formed on Ti substrates by thermal decomposition and annealing at 340°C–450°C. The effects of the annealing temperature on the structure, surface morphology, surface composition, and capacitive performance of the coatings were investigated using X‐ray diffraction analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy, X‐ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The XRD and TEM analyses showed that 360°C is greater than but very close to the crystallization temperature of the 70%IrO₂–30%ZrO₂ oxide coating. The 70%IrO₂–30%ZrO₂ oxide coatings annealed at this temperature consisted of an amorphous matrix containing a few IrO₂ nanocrystalline particles (diameter of 1–2 nm). The degree of crystallinity of the coatings was approximately 13.2%. EIS analysis showed that the electrode annealed at 360°C exhibited the highest specific capacitance, which was much higher than that of the electrode annealed at 340°C (which had a purely amorphous structure) as well as those of the electrodes annealed at 380°C and 400°C (which had higher degrees of crystallinity). On the basis of the obtained results, the following conclusion can be drawn: oxide coatings prepared at temperatures slightly higher than the crystallization temperature of the oxide and containing conductive nanocrystalline particles exhibit the best capacitive performance. We suggest that this phenomenon can be explained by the fact that the electronic conductivity of the coating is greatly improved by the presence of the homogeneously distributed conductive nanocrystalline particles in the amorphous matrix. Furthermore, the protonic conductivity and loose atomic configuration of the amorphous structure of the electrode are not adversely affected by the annealing treatment.     

Study on characterization of pyrolysis and hydrolysis products of poly(vinyl chloride) waste

Poly(vinyl chloride) PVC pyrolysis and hydrolysis are conducted in a fixed bed reactor and in an autoclave, respectively, under different operating conditions such as the temperature and time. The product distribution is studied. For the PVC pyrolysis process, the main gas product is HCl (55% at 340°C), there is 9% hydrocarbon gas (C₁–C₅), the liquid product fraction is about 5% (at 340°C), and the solid residue fraction is about 31% (at 340°C). For the hydrolysis process, the main gas product is HCl (55.8% at 240°C) and the solid residue is about 49.6% (at 240°C). The pyrolysis liquid product is analyzed by using gas chromatography with magic‐angle spinning. Aromatic hydrocarbons are the main class (90%), of which the major part is benzene (33%). The residue produced through pyrolysis and hydrolysis is investigated by high‐resolution solid‐state ¹³C‐NMR. These details revealed by the high‐field NMR spectra provide importmant information about the chemical changes in the PVC pyrolysis and hydrolysis process. The mechanism of PVC hydrolysis dechlorination is also discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3252–3259, 2003     

Thermal characteristics of iron(III), cobalt(II), and copper(II) complexes of dipyridylamine anchored on polystyrene-divinylbenzene copolymer

Polystyrene-divinylbenzene (PS-DVB) (partially chloromethylated) has been modified by anchoring dipyridylamine (DPA) followed by subsequent complexation with Fe(III), Co(II), and Cu(II). Analytical and spectroscopic evidence has been presented to confirm the attachment of the metal-dipyridyl complex on the PS-DVB matrix. All the metal-loaded polymers exhibit appreciable improvement in thermal stability relative to the base polymer, the initial decomposition temperature and stability order being PS-DVB-DPA-Cu(315°C) > PS-DVB-DPA-Fe(II) (310°C) > PS-DVB-DPA-Co (300°C) > PS-DVB-DPA (280°C) = PS-DVB.DTA studies reveal exothermic peaks between 300 and 380°C, 420 and 440°C, and 500 and 700°C, which are ascribable to the exothermic cleavage of the PS-DVB-DPA matrix. The glass transition temperatures of the modified polymers do not reveal any characteristic difference from the corresponding value for the base polymer. © 1993 John Wiley & Sons, Inc.     

Simulation of chemical rate processes in short contact time coal liquefaction

Conversions and product distributions from the thermal dissolution of Liddell coal in the presence of tetralin have been simulated by a system of second-order rate equations. Satisfactory correlation with experimental data is obtained over the range of temperatures studied, i.e. 380–420 °C.     

Thermal Dissolution of Coking Coals in the Anthracene Fraction of Coal Tar

The thermal dissolution of two samples of 1GZhR and ZhR coal in the anthracene fraction of coal tar is studied. The yield of quinoline-soluble products increases considerably in the temperature range of coal softening. Optimal thermal-dissolution conditions are determined for selective production of quinoline-soluble pitch-like products. At 350–380°C, the yield of quinoline-soluble products is 70–73% after 1–2 h. The yields of the distillate fraction and the gas are 0.9% and 0.2%, respectively. The ash-free pitch-like product is a plastic mass with a softening temperature of 76–81°C. It consists mainly of polycyclic aromatic hydrocarbons with a few short alkyl substituents in the aromatic rings. The spatial structure mainly includes poorly structured polycyclic aromatic molecules of the γ component. The proportion of relatively ordered graphitelike packets is 31–37%. Each packet contains five stacked polycyclic aromatic molecules of diameter 17 Å. In terms of its composition and plasticity, the product is suitable as a source of alternatives to coal pitch.     

Flash pyrolysis of Australian coals: Effects of pre-oxidation and of oxygen in the inlet gases on formation of agglomerated material

Addition of oxygen to nitrogen in the inlet gas during flash pyrolysis at 600 °C reduced the amount of char agglomerate formed from a relatively strongly caking Liddell seam coal and a weakly caking Millmerran seam coal. The reduction of agglomeration was significant over the entire ranges of variables used, viz, oxygen concentrations in the inlet gas of 2.62–10.5% (v/v) and oxygen to coal ratios of 0.02–0.12 (wt/wt). Pre-oxidation at 400 °C with solids residence times below 2 s, inlet concentrations of oxygen up to 10.5% and oxygen to coal ratios up to 0.10 (wt/wt) also effectively reduced agglomeration of Liddell coal. In terms of minimizing the oxygen requirement to obtain essentially nonagglomerating solids, the preferred method was found to be pre-oxidation followed by oxidative pyrolysis. The reduction of agglomeration by oxygen appears to be due to a combination of the extent of coal oxidation and the extents of polymerization and chemical condensation of the coal structure.