H-donor Solvents Research Articles

Characteristics of residues from thermal and catalytic coal hydroliquefaction ☆

The properties of residues from thermal or catalytic coal hydroliquefaction experiments were characterised by the ultimate, proximate analyses. The relations between the properties of the residues and the liquefaction reaction conditions, such as temperature, time, catalyst, H-donor solvent and atmosphere were investigated. Variations in H/C ratio and organic volatile matter (OVM) content of the residues with liquefaction conditions and coal conversion were studied. Results show that liquefaction temperature and time are main factors that control the organic properties of the residues. The roles of the Fe–S catalyst and H-donor solvent are to reduce the proportion of condensation products in the residue rather than increase the extent of polymerisation. Consequently, coal liquefaction conversion is improved by 100% by the catalyst, but H/C ratio and OVM content of the residues are not significantly decreased.

Optimization of Two-Stage Liquefaction of Tanito Harum Coal with FeNi Catalyst Supported on Carbon Black

Two-stage liquefaction of Tanito Harum coal (Indonesian sub-bituminous coal) was examined in an autoclave of 50 mL capacity at various temperatures for the first stage and various reaction times for the first and second stages under the hydrogen pressure of 15 MPa, using Fe(10 wt %)Ni(10 wt %) catalyst supported on carbon nanoparticles (Ketjen Black:KB). When the total reaction time in the first and second stages was fixed to 120 min, the best conditions of two-stage liquefaction were at 380 °C for 15 min in the first stage and then at 450 °C for 105 min in the second stage at a hydrogen pressure of 15 MPa, providing the maximum oil yields of 80 and 66 wt % (daf coal base) with or without H-donor solvent, respectively. The results also showed that these conditions produced fewer amounts of hydrocarbon gases and lower sulfur content in the oil. The conversion of H-donor solvent (tetralin) after the liquefaction was much lower (13%) than that of the single-stage liquefaction (21%). In addition, the residue yield was much lower (9%) than that of the single-stage (15%) in the solvent-free liquefaction. It is confirmed that prolonged reaction time in the second stage is more favorable than in the first stage. The effects of the first-stage (low temperature) liquefaction both with and without solvent are discussed to explain the optimum conditions of two-stage liquefaction.

00/02273 Research on coal reactivity: making a comparison between hydrogenation with H-donor solvent and thermogravimetry in N 2 atmosphere

00/02273 Research on coal reactivity: making a comparison between hydrogenation with H-donor solvent and thermogravimetry in N 2 atmosphere

Optimized Solvent Amount in the Liquefaction of Adaro Coal with Binary Sulfide Catalyst Supported on Carbon Nanoparticles

Liquefaction of Adaro coal was performed in an autoclave of 50 mL capacity, at variable solvent (tetralin)/coal ratios from 0 to 2 in single and two stages under the reaction hydrogen pressure of 15 MPa by using FeNi and NiMo catalysts supported on carbon nano particles (Ketjen Black). The maximum oil yield (68%) was obtained at the donor solvent/coal ratio of 1, while the solvent/ coal ratio of 0.5 gave the minimum oil yield (38%) in the single- and two-stage liquefaction with FeNi/KB catalyst. Solvent-free liquefaction maximized the hydrocarbon gas/oil yield ratio with FeNi/KB. The catalyst giving a high oil yield (68%) in the liquefaction with tetralin as an H-donor solvent was forced to give a low oil yield when 1-methylnaphthalene was used as non-H-donor solvent. In a marked contrast, NiMo/KB catalyst gave the minimum oil yield at the ratio of zero for the single stage and provided high oil yield (73%) with the nondonor as well as H-donor solvent.

00/01186 Research on coal reactivity: making a comparison between hydrogenation with H-donor solvent and thermogravimetry in N 2 atmosphere

00/01186 Research on coal reactivity: making a comparison between hydrogenation with H-donor solvent and thermogravimetry in N 2 atmosphere

99/03479 Research on coal reactivity: making a comparison between hydrogenation with H-donor solvent and thermogravimetry in N 2 atmosphere : Feng, J. et al. Proc. Annu. Int. Pittsburgh Coal Conf., [computer optical disk], 1988, 15, 13562-1363

99/03479 Research on coal reactivity: making a comparison between hydrogenation with H-donor solvent and thermogravimetry in N 2 atmosphere : Feng, J. et al. Proc. Annu. Int. Pittsburgh Coal Conf., [computer optical disk], 1988, 15, 13562-1363

Waxy polyethylenes from solution thermolysis of high density polyethylene: inert and H-donor solvent dilution effect

High density polyethylene batch thermolysis has been performed in dilute solutions to obtain waxy products with number-average molar masses in the range of 2000 to 6000 g mol −1. In relation to a classical bulk thermolysis (390°C, 6 h) which affords branched waxy polymers, dilution with phenylether permits controlled diffusion reactions modifying the product characteristics: low molar masses, narrow distribution, high crystallinity, rich in α-olefins and few long branching formation. A hydrogen donor solvent (tetralin), acting on the free radical degradation pathway, affords a lower fragmentation level of the main chains and short chains branching. In addition, a high level of tetralyl radicals grafting on the α-olefin is observed. Adjustment of the process conditions might give tailor-made waxy polymers to use just as they are or after chemical modifications of the olefinic functions.

The aryl ether bond reactions with H-donor solvents: guaiacol and tetralin in the presence of catalysts

The aryl ether bond reactions with H-donor solvents: guaiacol and tetralin in the presence of catalysts

The aryl ether bond reactions with H-donor solvents: guaiacol and tetralin in the presence of catalysts

The effect of homogeneous catalysis, Fe and Ru, on the conversion of guaiacol in tetralin to catechol and phenol has been investigated as a model for the behaviour of the aryl-oxy linkage that is found in wood, peat and younger coals. In the absence of catalyst and at low ratios of guaiacol to tetralin, the primary product is catechol. Kinetic analysis has confirmed that the rate constant for this primary and rate determining step is given by an Arrhenius pre-exponential factor of 10 13.8 s −1 with an activation energy of 215 kJ mol −1. The activation energy found is in good agreement with those of other investigators and lies between the values proposed for homolytic fission (>240 kJ mol −1) and for a concerted or pericyclic reaction (188 kJ mol −1). In the presence of catalysts the rate is not changed; however, the yield of a secondary product phenol is increased with both Fe and Ru. Separate experiments confirmed that the selectivity of catechol to phenol conversion was markedly increased in the presence of these catalysts. There is strong evidence for the formation of catecholato-iron complexes and this suggests that in pyrolysis and liquefaction of biomass and young coals there may well be a role for homogeneous catalysts in directing the product slate towards useful intermediate chemicals such as phenols.

Catalytic hydroliquefaction of coal macerals: Comparison with raw coal

Catalytic hydroliquefactions (HL) of two coals (Freyming, France and Point of Ayr, United Kingdom) and their macerals were studied in a microautoclave in the presence of an H-donor solvent (tetralin). The main results of the study were related to (i) a comparison between the behaviours of such coals or macerals in the HL process; the two raw coals showed the same total conversion, and similar wt% of oil, asphaltene and preasphaltene fractions, (ii) the contribution of each maceral to the global coal liquid; the additive effect was checked, but no synergetic effect was found (using HL and the present type of liquid phase analysis) for a ‘synthetic coal’. Raw coals, vitrite and exinite had the same total conversion, whereas that for fusite was much lower, and (iii) a detailed identification of some individual compounds or of series of homologous compounds; this was made for oil fractions. 25% of these fractions were able to be investigated by GC/MS, i.e. 5–10 wt% of the initial coal. Concentrations of a large number of compounds were determined and compared from one maceral to another, and general tendencies could be deduced.

Influence of the type of solvent on coal liquefaction with different catalysts

The liquefaction behaviour of a series of solvents in coal liquefaction both without catalyst and with two catalysts, red mud (an Fe 2O 3 catalyst) and CZMFA2 (a CoZnMo/Al 2O 3) catalyst), was evaluated. Three H-donor solvents (tetralin, 9,10-DHA and 1,2,3,4-THQ), three non-donor solvents (naphthalene, anthracene and phenantrene) and two industrial type solvents (anthracene oil and creosote oil) were tested. The experiments were conducted in a 250 ml autoclave, with 10 g of a subbituminous A coal, 30 g of solvent, 425 °C, 17 MPa operating pressure, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of a solvent is greatly influenced by the type of catalyst used and viceversa, the catalyst effect depends on the solvent utilized. Industrial type solvents can give better coal conversions than strong H-donor solvents if appropriate catalysts are used

EXTRACTION OF LIGNITE WITH TOLUENE IN SUB- AND SUPERCRITICAL STATES

Nine Chinese lignite samples were extracted with toluene using a nonisothermal experimental technique at sub- and supercritical conditions in a semi-continuous apparatus. The effects of lignite properties, pressure, and H-donor solvent on the yields were investigated. The results show that the oil yield is about 1.8 to 2.7 times that of Fischer assay and the conversion and extract yield increase linearly with the increase of volatile matter of lignite and pressure. When a H-donor solvent (tetraline) is added to the solvent (toluene), the conversion and extract yield are increased

Modelling of hydrogen transfer in coal hydroliquefaction: 6. Relative rate constants of hydrogen transfer from hydroaromatic solvents to radicals generated by thermolysis of benzylphenylether

A method based on competitive kinetics is employed for measuring relative rate constants for hydrogen transfer from four H-donor solvents (9,10-dihydrophenanthrene, tetralin, indan and 1,2,3,4-tetrahydroquinoline), for the stabilization of free radicals generated by thermal decomposition of benzylphenylether at 300 and 400 °C. These relative rates are slightly different and are of the same order of magnitude as the values obtained for the liquefaction of bituminous Freyming coal. It appears that the previously defined performance indices are more suitable than the relative rate constants for classifying these hydroaromatic solvents.

IRON COMPOUNDS AND C0-Mo/Al2O3 CATALYSTS: ACTIVITY IN DIRECT HYDROGENATION OF A SUBBITUMINOUS A COAL WITH AN H-DONOR SOLVENT

Abstract The effectiveness of different catalysts were compared in coal liquefaction experiments using a 250 ml stirred autoclave, 10 g of a Spanish Subbituminous A coal, 1 hour reaction time, 17 MPa operating pressure, 400 rpm stirring speed, at 425 and 450 °C with 2/1 and 3/1 tetralin/coal ratio. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents. Three iron-oxide containing catalysts: red mud, an Fe2O3 aerosol and Cottrell ash (by-product of the aluminium industry); and three alumina supported catalysts: CMA, which is a conventional CoMo/Al2O3 catalyst, CZMA which in addition contains Zn as a second promoter, and CZMFA which has the alumina acidified with fluorine and also contains Zn, were compared. It has been reported that the addition of Zn and of F enhances the HDS, cracking, hydrocracking or hydrogenating activities of CoMo/Al2O3 catalysts in experiments with pure compounds. The objective of this study was to determine if the addition of Zn and of F has also a beneficial effect in the catalyst activities in coal liquefaction, and also to compare cheap iron containing catalysts with the more sophisticated and expensive alumina supported ones. The results showed that 1) Catalysts effects depend on the operating conditions used, and that with tetralin, a strong H-donor solvent, they never are very pronounced. 2) The supported catalysts have higher activities in coal liquefaction than the iron ones, but there are no significant differences among the catalysts within each group. 3) Zn, which is a cheaper metal than Co, can substitute succesfully for half the amount of Co and retain the activity of the CoMo/Al2O3 catalyst in coal liquefaction. 4) The addition of F to the CoMo/Al2O3 catalyst does not show a benefecial effect

The cathodic scission of aromatic derivatives in the presence of nitrones as spin markers: on the reactivity of transient nitroxides in weak H-donor solvents: Part 2. On the cleavage of aromatic sulphones and halides in benzonitrile

Aromatic sulphones and some aromatic halides are reduced electrochemically directly and indirectly in benzonitrile in the presence of tert-butylphenylnitrone as a spin trap. In most cases, three line spectra are obtained in ESR attesting to the presence and the addition of free radicals, the nature of which is discussed.

The cathodic scission of aromatic derivatives in the presence of nitrones as spin markers: on the reactivity of nitroxides in weak H-donor solvents: Part 1. Use of dimethyl sulphoxide

Aromatic bromides and sulphones, taken as ArX model molecules, were cathodically cleaved in DMSO in the presence of tert-butylphenylnitrone. Under such conditions, the expected nitroxide (obtained by addition of the transient radical on the scavenger) is not always stable at the cathode interface in a solvent that is a weak H-atom donor and may evolve to other nitroxides whose formation is followed by means of ESR techniques.

Hydroliquefaction of coal catalysed by tin compounds

Although tin compounds have been shown to be active in hydroliquefaction of coal, the active tin species during the liquefaction has not yet been elucidated. Some recent work suggests that metallic tin promotes the liquefaction reaction. In this study, the hydroliquefaction of French Freyming coal was investigated in a batch reactor between 350 ° and 430 °C, using non-porous SnO 2 aerosol with a low particle size (15 nm) as a catalyst precursor, or presulphided tin oxide or commercial metallic tin. Chemical analysis of the liquid phase was achieved by solvent extraction in n-hexane, toluene or THF. The hydrogen consumptions (from the gas phase or from the donor solvent), were also estimated. The main experimental techniques used for catalyst characterizations were applied to the residue of hydroliquefaction: 119Sn and 57Fe Mössbauer spectrometry, X-ray diffraction and electron microscopy associated with X-ray spectrometry. Tin sulphide was generally observed as the main product with small amounts of oxidized tin species. The size of SnS particles implies sintering, possibly due to mobile tin species such as metal, although this latter could not be detected. No evidence of coking of the surface of SnS was found. In some cases the intermetallic compound FeSn 2 was shown, as formed by reaction of tin with pyritic iron of the mineral matter. By comparing the results of coal conversion with those of tin characterization, the active species was thought to be SnS, on which a competitive adsorption of H 2S should proceed. This results in a shift of the mode of hydrogen transfer to the coal (from H-donor solvent as opposed to hydrogen itself), as the partial pressure of H 2S in H 2 increased.

Influence of organic coal structure on liquefaction behaviour: An update with emphasis on low severity conditions

The influence of coal structure on primary conversions and oil yields under different relatively mild liquefaction regimes has been investigated. Pre-soaking of coal/H-donor solvent slurries at 250°C increased conversions and the level of hydrogen transfer at short contact times (SCT <10 min) demonstrating the importance of solvent accessibility. However, contrary to other studies, prior removal of THF-extractable material (mobile phase) from one bituminous coal actually gave rise to higher conversions to pyridine — solubles for non-donor polynuclear aromatic compounds (PAC), such as naphthalene, phenanthrene and pyrene. These findings highlight the difficulties in relating primary conversions to coal characteristics. In contrast, oil yields have been found to broadly increase with decreasing rank in both H-donor solvent extraction with a process solvent and dry catalytic hydrogenation. However, in SCT tetralin extraction where poor physical contact between coal and solvent exists, neither total conversion nor oil yield correlates with rank.

Catalytic activity of oxide and sulfide ore catalysts in lignite hydrogenation

The activity of various iron-containing ore catalysts during hydrogenation of Kansk-Achinsk lignite into liquid products in H-donor solvent (tetraline) has been studied. Ore samples contained pyrite, hematite and magnetite minerals. The most active appear to be pyrite samples. The catalytic effect of ore systems is, apparently, associated with the fact that during hydrogenation more active than tetraline H-donors are formed due to the hydrogenation of polycyclic aromatic molecules produced by thermal destruction of lignite.

Influence of preswelling on liquefaction of coal

Coals of different ranks were preswollen using THF as swelling solvent. The swelling ratio was higher for low rank coals. The preswollen coals improve the THF soluble materials after liquefaction with tetralin and other H-donor solvents. This enhancement was higher for coal with higher swelling ratio.