Retrogressive Reactions Research Articles

Co-Liquefaction of Elbistan Lignite with Manure Biomass; Part 3 - Effect of Reaction Time and Temperature

Most of the liquefaction process were carried out in a batch reactor, in which the residence time of the liquefaction products is long enough to favour the retrogressive reactions. To minimize retrogressive reactions, the liquefaction of coal was carried out in a flowing solvent reactor in which a fixed bed of coal is continuously permeated by hot solvent. Solvent flowing through the coal bed carries the liquefaction products out of the reactor. Unlike experiments carried out under similar conditions in a batch reactor no increase in solid residue is observed during long time high temperature runs in the flowing solvent reactor. There is a greater appreciation of the importance of retrograde, or polymerization, reactions. If the free radicals formed when coal breaks down are not quickly capped with hydrogen, they react with each other to form large molecules that are much harder to break down than the original coal. Reaction time impacts both the co-liquefaction cost and the product yield. So as to study this idea, the experiments of Elbistan Lignite (EL) with manure co-liquefaction carried out by changing the reaction time from 30 to 120 minutes. As a result, the greatest oil products yields obtained at 60 minutes. Therefore, by thinking about the oil products yield values acquired, the optimal reaction time was obtained to be 60 minutes for Elbistan lignite (EL) with manure liquefied with the temperature of 350°C and 400°C. Above 425°C did not examine because solvent (tetraline) loses its function after 425 °C. The obtained optimum temperature found 400°C due to higher total conversion of liquefaction products and also oil+gas yields.

Co-liquefaction of Elbistan Lignite with Manure Biomass; Part 2 - Effect of Biomass Type, Waste to Lignite Ratio and Solid to Liquid Ratio

Most coal hydrogenation processes require a large quantity of hydrogen. In general, a coal derived liquid such as anthracene oil was used as a hydrogen donor solvent. Tetralin, partially hydrogenated pyrene, phenantrene and coal-derived solvents, which contain hydroaromatic compounds, are efficient solvents to donate hydrogen. In an attempt to reduce the high cost of hydrogen, part of the hydrogen was replaced by a low cost hydrogen donor solvent. This must be hydrogenated during or before the process and recycled. To reduce the cost of hydrogen donor vehicles instead of liquids recycled from the liquefaction process or several biomass types, industrial by products, liquid fractions derived from oil sands bitumen were successfully used to solubilize a coal from the past. In an attempt to reduce the high cost of hydrogen, part of the hydrogen was replaced by a low cost hydrogen donor solvent. However, when hydrogen is supplied from the hydroaromatic structures present in the solvent, the activity of coal minerals is too low to rehydrogenate the solvent in-situ. Nevertheless, a decrease of using oxygen, in addition to enhanced usage of the hydrogen supply by using various waste materials might lead to a decrease of the cost of the liquefaction procedure. So instead of using tetralin another feeding material such as biomass is becoming another solution improving hydrogen donor substances. Most of the liquefaction process were carried out in a batch reactor, in which the residence time of the liquefaction products is long enough to favour the retrogressive reactions, early studies which are related to liquefaction of coal with biomass generally focus on the synergetic effects of coal while biomass added. Early studies which are related to liquefaction of coal with biomass generally focus on the synergetic effects of coal while biomass added. Alternatively, to understand the hydrogen transfer from biomass to coal, in this study, Elbistan Lignite (EL) with manure, tea pulp and waste plastic liquefied and to understand hydrogen quantity change after liquefaction, (H/C)atomic ratio of products obtained. Due to the highest oil conversion of manure biomass and highest (H/C)atomic ratio results show manure is the favourable biomass for EL amongst the other biomass used. And liquid/solid ratio optimized. About high total conversion of oil products the optimum ratio obtained as 3/1. And also EL with manure liquefied with the w/EL ratio between 0:1 to 1:1. As a result, by thinking about the yield values obtained, the optimum waste to lignite ratio found to be 1:1.

Dykes as physical buffers to metamorphic overprinting: an example from the Archaean–Palaeoproterozoic Lewisian Gneiss Complex of NW Scotland

The early history of polymetamorphic basement gneiss complexes is often difficult to decipher due to overprinting by later deformation and metamorphic events. In this paper we integrate field, petrographic and mineral chemistry data from an Archaean tonalitic gneiss xenolith, hosted within a Palaeoproterozoic mafic dyke in the Lewisian Gneiss Complex of NW Scotland to show how xenoliths in dykes may preserve signatures of early tectonothermal events. The Archaean tonalite–trondhjemite–granodiorite (TTG) gneisses of the Lewisian Gneiss Complex are cut by a suite of Palaeoproterozoic ( c . 2400 Ma) mafic dykes, the Scourie Dyke Swarm, and both are deformed by later shear zones developed during the upper greenschist- to lower amphibolite-facies Laxfordian event (1740 – 1670 Ma). Detailed field mapping, petrographic analysis and mineral chemistry reveal that a xenolith of TTG gneiss entrained within a Scourie dyke has been protected from amphibolite-facies recrystallization in a Laxfordian shear zone. Whereas the surrounding TTG gneiss displays pervasive amphibolite-facies retrogression, the xenolith retains a pre-Scourie dyke, clinopyroxene-bearing metamorphic assemblage and gneissic layering. We suggest that retrogressive reaction softening and pre-existing planes of weakness, such as the c . 2490 Ma Inverian fabric and gneiss–dyke contacts, localized strain around but not within the xenolith. Such strain localization could generate preferential flow pathways for fluids, principally along the shear zone, bypassing the xenolith and protecting it from amphibolite-facies retrogression. In basement gneiss complexes where early metamorphic assemblages and fabrics have been fully overprinted by tectonothermal events, our results suggest that country rock xenoliths in mafic dykes could preserve windows into the early evolution of these complex polymetamorphic areas. Supplementary material: Electron microprobe analyses and analytical spot locations are available at: https://doi.org/10.6084/m9.figshare.c.3809545

26.液化反応の初期過程に関する研究 : (1)液化反応の初期段階の制御と液化油収率の向上

26.液化反応の初期過程に関する研究 : (1)液化反応の初期段階の制御と液化油収率の向上

Thermodynamic forward modeling of retrogressive hydration reactions induced by geofluid infiltration

We have developed a new methodology for forward analysis of retrogressive hydration (rehydration) reactions by an improved thermodynamic forward modeling technique based on a differential thermodynamic approach (Gibbs’ method). Based on natural observations and theoretical considerations, the progress of a rehydration reaction is modeled by incorporating a change in the effective bulk composition on account of the breakdown of the non-equilibrated phase and the amount of water infiltration into the system. Forward analyses of rehydration reactions under greenschist-facies conditions show that (1) the reaction progress of rehydration is proportional to the external water supply, and (2) the mineral compositions of equilibrated minerals are mainly controlled by P–T conditions and are similar to those in the global equilibrium model. Calculated results are in accordance with natural observations of rehydration reactions in greenschist-facies rocks, which supports the validity of the proposed model. The proposed model can be used as a basic forward model for various inversion analyses and numerical simulations and thus to understand the distribution and behavior of geofluids.Graphical abstract.

NITROGEN-BEARING CORDIERITE AND TOBELITE IN META-RHYOLITES FROM THE CEUTA ZONE (RIF BELT, SPAIN): EVIDENCE FOR MOBILITY OF NITROGEN IN THE CONTINENTAL CRUST

We have conducted a detailed chemical, structural, and spectroscopic study of the alteration products of cordierite in meta-rhyolites from the Ceuta zone (Rif belt) with the aim of determining the nature of the products, the main stages of cordierite transformation and the metamorphic pressure-temperature path. In this zone, meta-rhyolites are in tectonic contact with granulites and migmatites interpreted as the feeder zones for the granitic melt. This study has revealed that N-bearing magmatic cordierite was transformed in concentric aggregates of mica with decreasing NH 4 contents (tobelite, NH 4 -bearing white mica, and K-micas), probably through three successive processes: deuteric alteration, prograde reactions, and retrogressive reactions. The presence of N in cordierite is interpreted to be due to the transfer of the NH 4 , initially contained in biotite from granulites, during the melting stage. This finding suggests that magmatic cordierite can act as an important nitrogen reservoir during formation of granite melts and differentiation.

Pyrolysis behavior and bonding information of coal — A TGA study

Pyrolysis of 34 Chinese coals is studied in a TGA coupled with a mass spectrometer. The mass loss registered in TGA during temperature programmed heating is attributed mainly to devolatilization of fragments generated from cleavage of covalent bonds because retrogressive reactions of small volatile radical fragments do not produce solid products and that of large volatile radical fragments are slow and occur mainly outside of the sample crucible. Each of the DTG curves is fitted by a set of sub-curves and regression using 6 sub-curves yields the best fitting. Each of the 6 sub-curves is assigned to cleavage of a group of covalent bonds in coal, which is validated by model compounds and literature data. The trends in peak temperature and peak area of the sub-curves with respect to changes in C% in the coals are clear and similar to changes in some of the physical properties of coals. The analysis method presented is useful in analyses of coal structure and pyrolysis reactions. Furthermore, TG analysis is suggested to replace proximate analysis due to the rich volatile-temperature information and easy identification of volatiles generated from decomposition of carbonates.

Widespread Occurrences of Hogbomite-2N2S in UHT Metapelites from the Betroka Belt, Southern Madagascar: Implications on Melt or Fluid Activity during Regional Metamorphism

Ho« gbomite occurs in spinel^garnet^cordierite^sillimanite-bearing metapelites over an area of 60 km 12 km in the northern parts of the Betroka belt, southern Madagascar. X-ray diffraction analyses indicate that the ho« gbomites belong to the 2N2S polysome type ‘P63cm’with a1⁄4 5·718^5·723 — and c1⁄418·30^18·42 —.The chemical composition of ho« gbomite varies over a relatively wide range (in wt %):TiO21⁄4 3·82^6·09, Al2O31⁄4 59·45^63·04, Cr2O3 0·63, FeO1⁄4 20·14^30·7, MgO1⁄4 2·19^5·76, MnO 1·35, ZnO 8·78, and CaO 0·27.The ho« gbomites form solid solutions involving the substitutions (MgþFe2þþMnþCa)1⁄4Zn, 2(AlþCrþFe3þ)1⁄4Tiþ (MgþFe2þþMnþCaþZn), and (AlþCr)1⁄4Fe3þ. The ho« gbomite was formed in polyphase domains hosted by discrete magnetite, ilmenite, and/or hematite in close association with spinel, corundum, and/or rutile. Petrographic characteristics and the compositions of ho« gbomite suggest that this mineral was formed by various retrogressive reactions in different microdomains. Ho« gbomite forms at the expense of corundum spinel ilmenite Ti-hematite rutileþH2O and exhibits systematic compositional relationships with the neighboring spinel in Fe2þ^Mg, Fe3þ^Al and Fe2þ^Zn, suggesting attainment of equilibrium between these two minerals. The ho« gbomite-bearing rocks underwent ultrahigh-temperature (UHT) crustal metamorphism following a clockwise P^T trajectory. The textural features suggest the dehydration melting reaction biotiteþ sillimaniteþ quartz1⁄4 cordieriteþgarnetþmelt. The peak mineral assemblage garnetþ cordieriteþ spinelþ sillimaniteþ quartz was stabilized at 880^10608C and 4·5^6·6 kbar. Decompression cooling is evident from a reaction forming cordierite at the expense of spinel and quartz and a cordierite^spinel corona formed between garnet and sillimanite by the reaction garnetþ sillimanite1⁄4 cordieriteþ spinel. Ho« gbomite crystallization took place after the peak metamorphic event, probably accompanied by anatectic hydrous melts formed during metamorphism or introduction of hydrous fluids along shear zones over a wide area. We propose that ho« gbomite can evidently grow even at high metamorphic grade (T 8008C and P 4 kbar) if a source of water is present, and is an indicator of significant hydrous melt or fluid activity during the early retrogressive stage of regional metamorphism.

Enhancement of Caking Property of Slightly Caking Coal by Addition of Hydrogen Donor

In this study, relation between the amount of transferable hydrogen of coal tar pitch (CP) and fluidity of the slightly caking coal adding CP was discussed in order to enhance fluidity of the slightly caking coal. In particular, additive effects of two constituents (toluene soluble but hexane insoluble; TSHI and pyridine soluble but toluene insoluble; PSTI) separated from solvent extraction of CP were estimated. As a result, an amount of transferable hydrogen of these constituents increased slightly by high temperature (360–420°C) hydrogenation. Fluidity of Enshu coal (slightly caking coal) increased by addition of these hydrogenated constituents (TSHI and PSTI). Because retrogressive reaction among the molecules in Enshu coal was suppressed by hydrogen donation from the increased transferable hydrogen in TSHI or PSTI to the molecules in Enshu coal. Further, additive effect of fluoranthene (FL) was estimated. For all tested coals, maximum fluidity of coal adding hydrogenated FL (HFL) was larger than that adding FL. The difference was large for coals containing much of oxygen. Accordingly, retrogressive reaction among the oxygen containing groups in the coal molecules was suppressed by hydrogen donation from the transferable hydrogen in HFL. Estimating from the polarizing micrographs of cokes from coal adding HFL, it was clarified that thermal plasticity of coal was enhanced by addition of HFL, not by thermal plasticity of HFL itself.

Mg-rich chloritoid in a corundum-bearing zoisite rock from the Sanbagawa belt, central Shikoku, Japan

Mg-rich chloritoid with the ratio Mg/(Mg + Fe2+) = 0.37 to 0.49 was found in a corundum-bearing zoisite rock from the Besshi area in the Sanbagawa metamorphic belt, Japan. The zoisite rock consists mainly of zoisite, corundum, garnet, and amphibole. Corundum was retrogressively replaced by secondary chloritoid, zoisite, clinozoisite, chlorite, and paragonite. Staurolite rarely occurs in aggregates of the secondary phases (chloritoid, chlorite, and paragonite), which occur along the cracks in corundum, and is surrounded by chloritoid. This fact indicates that chloritoid was formed by the following retrogressive reaction: 7chlorite + 8corundum + 4staruolite + 15H2O →51chloritoid. The estimated temperature for the above univariant reaction in the MASH system is 637 ± 30 °C at 10 kbar and 744 ± 34 °C at 20 kbar. The textural evidence and the estimated temperature suggest that chloritoid formed during the exhumation stage from eclogite to epidote-amphibolite facies conditions.

Catalytic Direct Liquefaction of High-Sulfur Coals and Their Blends with Asphaltite in the Absence of a Solvent

Two high-sulfur Turkish coals (Mengen and Kangal) and an asphaltite (Avgamasya) were liquefied with and without the catalyst precursors ammonium heptamolybdate (AHM) and ammonium tetrathiomolybdate (ATTM) at 300, 350, 400, and 450 °C. Blends of these coals with the asphaltite were also liquefied using ATTM. Effective conversions of both coals into oils and into asphaltene and preasphaltene fractions were achieved with both catalyst precursors, although ATTM was more effective than AHM. Maximum conversion for Mengen coal with ATTM (89.2%) was achieved at 400 °C, although the maximum yield of oils (56.9%) was obtained at 450 °C. Kangal, in the presence of ATTM, gave maximum conversion (87.7%) at 400 °C; the corresponding oil yield (49.6%) was not much less than that obtained at 450 °C (49.9%). Some retrogressive reactions toward the formation of aromatics were observed during liquefaction at 450 °C in the presence of AHM or ATTM with both coals. Also, using these catalyst precursors results in effective hyd...

Ductile deformation of garnet in mylonitic gneisses from the Münchberg Massif (Germany)

Mylonitic gneisses from the Münchberg Massif contain single grains (type I) and polycrystalline aggregates (type II) of garnet displaying a distinct elongation parallel to a macroscopic lineation which is interpreted as the result of ductile deformation. Lattice-preferred orientations of quartz (textures) symmetrical to the macroscopic foliation and lineation and the lack of rotational microfabrics indicate that the bulk deformation was pure shear at least during the latest strain increments. Garnet textures measured by EBSD together with microprobe analyses demonstrate that these two structural types of garnet can be related to two different processes of ductile deformation: (1) For the single grains stretching can be attributed to diffusion creep along grain boundary zones (Coble creep). The related mass transfer is indicated by the fact that primary growth zones are cut off at the long faces of the grains while the related strain shadow domains do not show comparable chemical zoning. Pressure solution and precipitation suitable to produce similar structures can be largely ruled out because retrogressive reactions pointing to the presence of free hydrous fluids are missing. (2) For the polycrystalline garnet aggregates consisting of cores grading into fine-grained mantles, dislocation creep and associated rotation recrystallization can be assumed. Continuous lattice rotation from the core to the outer polycrystalline rim allow a determination of the related dominant slip systems which are {100}<010> and equivalent systems according to the cubic lattice symmetry. The same holds for garnets which appear to be completely recrystallized. For this type of fine-grained aggregates an alternative nucleation model is discussed. Due to penetrative dislocation glide in connection with short range diffusion and the resulting lattice rotation, primary growth zones are strongly disturbed. Since for the considered rock unit of the Münchberg Massif peak metamorphic temperatures between 630 and 670 °C can be assumed, this study clearly demonstrates that the inferred processes of ductile garnet deformation can occur not only in HT regimes as often suggested in the literature even if embedded within a matrix of “low-strength” minerals like quartz, feldspars and micas.

Hydrogen Transfer in the Formation and Destruction of Retrograde Products in Coal Conversion

The conversion of coals to volatiles or liquids during pyrolysis and liquefaction is notoriously limited by the formation of retrograde products. Analysis of literature data for coals with grafted structures and for polymeric coal models demonstrates that the formation of volatile products from these materials does not correlate primarily with the weakness of the original bonding but correlates with the facility for retrogressive reaction. This analysis suggests further that simple recombination of resonance-stabilized radicals does not tend to yield true retrograde products, except in the case of aryloxy radicals. For pure hydrocarbon structural elements, radical addition to aromatic systems appears to be a key class of retrograde reactions, where the key factor is the kinetics of radical or H-atom loss from a cyclohexadienyl intermediate. We have used a mechanistic numerical model with a detailed set of radical reactions and thermochemically based kinetic parameters operating on a limited set of hydrocarbon structures to delineate important factors in mitigating retrograde processes. The modeling results show (1) how the "better" radical scavengers may reduce retrograde reaction at short reaction times but actually tend to increase it at longer times; (2) that the beneficial effects of H2 pressure at short reaction times are not primarily due to lowering of harmful radical concentrations by scavenging, nor to the maintenance of donor content; (3) that the benefit is due to the small population of free H-atoms thus produced, which are very active in causing increased scission of strong bonds; and (4) that under some conditions retrograde products are actually generated faster with added H2, but at longer reaction times and higher temperatures this temporary disadvantage of H2 is overcome by increased hydrogenolysis of those earlier-produced retrograde products. Thus, not only the cleavage of critical bonds in the original coal structures but also the net prevention of retrogression may be due to the H-transfer-induced cleavage of strong bonds.

Effect of Rapid Preheating on the Coking Behavior of Bituminous Coals: Retrogressive Reactions and Extract Yields

Mechanisms underlying observed changes in the plastic properties and swelling ability of weakly coking coals, induced by rapid heating to 400−450 °C, have been investigated. The enhanced softening would allow the shifting of coke blend compositions toward weakly coking coals. A surge in extractables content was observed at heating rates of >500 °C/s. After rapid heating, 25%−28% more of the mass of the weakly coking coal could be extracted. At these low temperatures (∼400−450 °C), repolymerization rates of solvent-extractables seem to be negligible. Increases in the extractables content that were determined by rapid heating clearly improve coke strengths via the related increase in thermoplasticity. However, when a “prime coking coal” was tested under similar conditions, no measurable effect of heating rate on the extractable contents was observed. A third “coking” coal showed behavior that was intermediate between these two cases. Taken together, the data strongly suggest the sequential occurrence of (i) fast retrogressive recombinations between reactive free radicals formed during thermally induced covalent bond cleavage reactions during the heat-up process, and (ii) slower repolymerization/recombination reactions occurring between the more-stable free radicals, observable at >450 °C. The example of the prime coking coal suggests that more of the reactive free radicals might be stabilized (quenched) by locally available hydrogen, irrespective of the heating rate. Liquefaction in the presence of hydrogen donors shows that high conversions to extractables are possible during slow heating. However, for transitional coals (between weakly coking coal and prime coking coals), pyrolysis yields are clearly sensitive to changes in heating rate. Transitional coals thus seem to be those that are marginally deficient in donatable hydrogen.

Thermal hydrocracking of Cold Lake vacuum bottoms asphaltenes and their subcomponents

The thermal chemistry of bitumen and heavy oils is extremely complicated, mostly because of the complex nature and the unknown molecular structure of different components that are present in these materials. In order to understand the molecular transformation of bitumen during upgrading better, the following approach was adopted: separate the bitumen into different components (asphaltenes and maltenes), characterize them in detail and react each fraction separately. In the present work, the results of thermal reaction of asphaltenes and its subfractions (A1–A4) separated by column chromatography are presented. Thermal hydrocracking of asphaltenes derived from Cold Lake vacuum bottoms (CLVB) was investigated, neat and in a hexadecane solvent at 440 °C (30 min and 13.8 MPa H 2). The amount of coke measured as methylene chloride insolubles remained relatively constant at about 25 wt.%, whether the asphaltenes reacted neat or in hexadecane. Increasing asphaltenes concentration in hexadecane had little effect on coke formation. Results from the present study were compared with those reported previously from our laboratory for the same CLVB asphaltenes, which were thermal hydrocracked in CLVB maltenes and in decalin, and produced significantly less coke than in hexadecane. Unlike the reaction in hexadecane, changing the concentration of asphaltenes in maltenes had a significant effect on coke formation. The results from the previous study were rationalized in terms of competing reactions between maltenes and asphaltene-derived radicals for hydrogen, solvating effects of the media on coke formation, and viscosity effects on the radical–radical combination to form coke. Hexadecane as a solvent was relatively inert when compared to maltenes under the same severity conditions and did not stabilize the reactive radicals or prevent retrogressive reactions. The thermal hydrocracking of CLVB asphaltenes subcomponents (A1–A4) was also investigated in hexadecane. A better correlation was obtained between the coke yield and the molecular weight than either microcarbon residue or the aromaticity of the subcomponents. Based on the lack of additivity in coke yield, it was concluded that a synergistic effect among the subcomponents was most likely responsible for the reduced coke yield obtained from processing the asphaltenes feed.

Search for retrogressive reactions accompanying demineralization in native and air-oxidized coals

This solid state 13C NMR study confirms, for coals, and extends, for air-oxidized coals, the claim that the Bishop and Ward strong aqueous-acid coal demineralization procedure [M. Bishop, D.L. Ward, Fuel 37 (1958) 191.] does not lead to the formation of detectable levels of cross-links in the organic matrix of these materials. The study was prompted by the demonstration that polymerization accompanies strong acid demineralization in lignin, and the recognition that the chemical environment created in air-oxidized coals contains introduced reactive functionality similar to that in the lignin. In particular, both contain oxidized benzylic carbon functionality that can undergo acid-catalyzed polymerization reactions. For two coals of differing rank, no acid-induced cross-link formation has been observed in the pristine or air-oxidized coals, within the 5 parts per thousand (ppt) sensitivity of the NMR technique used in this study.

Kinetic evaluation of progress in coal liquefaction in the 1t/d PSU for the NEDOL process

A kinetic analysis of coal liquefaction in flow reactors of the 1t/d Process Supporting Unit (PSU) for the NEDOL Process is reported. The coal liquefaction section of the PSU consists of a preheater and three liquefaction reactors in series. Progress of coal liquefaction in PSU has been investigated, focussing mainly on the changes in coal derived insoluble components through the preheater and the reactors. Summing up those results, a reaction kinetic model of coal liquefaction with retrogressive reaction was established and a mechanism of coal liquefaction in the process was elucidated.

Hydrocracking of Tetralin over NiW/USY Zeolite Catalysts: For the Improvement of Heavy-Oil Upgrading Catalysts

The reaction mechanisms of tetralin as a model compound of heavy petroleum fractions were investigated with the aim of improving bifunctional USY zeolite-based catalysts for heavy-oil hydrocracking. The major reaction path in the initial period was found to differ from that later in the reaction. In the initial reaction period, over USY catalysts with and without NiW sulfide, the reaction began with the formation of phenylbutyltetralin from two tetralin molecules by electrophilic aromatic substitution. Phenylbutyltetralin subsequently decomposed into benzene and octahydro tricyclic aromatic compounds. These reactions were catalyzed without the involvement of gaseous hydrogen and very likely lead to coke formation by chain reactions. Later in the reaction, tetralin and the above-mentioned heavy compounds were gradually hydrocracked over the bifunctional USY-supported NiW catalyst. These results indicated that the hydrogen supply from NiW sulfide to the acid site was not fast enough to prevent retrogressive reactions of partially hydrogenated polycyclic aromatic compounds. It was inferred that a closer relationship between the active sites of hydrogenation and cracking was needed for the improvement of bifunctional catalysts in heavy-oil upgrading.

99/01073 Coliquefaction of coal and waste plastics under milder hydrogen pressures : Yamaguchi, H. et al. Koatsuryoku no Kagaku to Gijutsu, 1998 7, (Proceedings of International Conference — AIRAPT-16 and HPCJ-38 — on High Pressure Science and Technology, 1997), 1233–1235

This chapter discusses the synergistic effects of coprocessing originated from interactions between coal and heavy oil. In a study described in the chapter, mixtures of Japanese Taiheiyo coal and Athabasca oil sand bitumen (AOB) with different coal concentrations were used as feeds. The results of the coprocessing reactions of mixtures with different coal concentration are shown. Although the original AOB contained no benzene insoluble fraction (BI), BI was produced with 5 wt% yield after the reaction of pure AOB. A mixture containing 2 wt% coals produced larger amount of HS and smaller amount of BI than the reaction of pure AOB. The addition of a small amount of Taiheiyo coal to AOB resulted in synergistic oil production by suppressing retrogressive reactions, similarly to a mixture of Forestburg Subbituminous C coal and Cold lake vacuum bottoms. With an increase in the coal concentration, the hexane soluble yield decreased, accompanied by an increase in the BI yield. Degree of hydrogen consumption for mixtures containing less than 25 wt% coal was relatively small while a serious increase was observed for mixtures containing more than 30 wt% coal.

Liquefaction behaviour of a Spanish subbituminous A coal under different conditions of hydrogen availability

A Spanish subbituminous A coal was liquefied in a 250-ml autoclave for 1 h, at 17 MPa hydrogen pressure and 400 rpm stirring speed. The liquid products were fractionated into oils, asphaltenes, and preasphaltenes using pentane, toluene and THF as extractive solvents. The effect of hydrogen availability on liquefaction yields was explored using different tetralin:coal ratios under different temperatures. The results are compared with those obtained in earlier studies [1, 2], under different hydrogen pressures and tetralin:coal ratios, and with other solvents and with catalysts. Total conversion, asphaltenes, preasphaltenes and oils increase while gases decrease when the tetralin:coal ratio is raised, not observing further conversion over 2:1, 3:1, 4:1 and 6:1 ratios, at 400, 425, 450 and 475°C, respectively. Retrogressive reactions are produced at 475°C for tetralin:coal ratios under 4:1 but not for higher ones. In order to obtain the highest conversion (≈84%), which coincides with vitrinite+exinite content, 475°C and 6:1 or higher tetralin:coal ratios have to be used. Such or higher conversions, can be obtained with more appropriate operating conditions (425°C, 3:1 solvent:coal ratio) if better solvents or active catalysts are used.