Hydrogen Donor Solvent Research Articles

Co-liquefaction of enriched coal maceral constituents and sawdust : Wang, Y. et al. Guocheng Gongcheng Xuebao, 2002, 2, (2), 156–160

Co-liquefaction of coal and sawdust was studied in the presence of hydrogen-donor solvent, tetralin. Coal samples were prepared through floatation of the Xinwen coal, followed by enrichment of maceral constituents. Sample I was rich in vitrinite and Sample II fusinite. Effects of reaction temperature, time and initial cold H2 pressure were studied on conversion, yield, especially oil yield, through comparison between these two samples. Because it is more difficult to be liquefied, Sample II, is greatly affected by changes in temperature and time. However, it is almost independent of change in initial cold H2 pressure, owing to the role of tetralin as hydrogen vehicle. Certain product(s) formed from thermolysis of sawdust can help hydrogenation of the intermediate (asphaltene and preasphaltene) in further forming oil products.

Preparation and photoreaction of organogels based on benzophenone

In this paper, first photoreactive low-molecular weight organogels are described. Benzophenone derivatives functionalised with two long alkylamides 1a–c were designed and synthesized as photoreactive gelator molecules. The compounds formed organogels in several hydrogen donor solvents, e.g. 2-propanol and 1,3,5-triisopropylbenzene. Microstructures of the gels by scanning electron microscopy (SEM) revealed a 3D fibrous network and spherical aggregation. Compound 4 based on isopropylbenzene having an octadecylamide, which was designed as a photochemical hydrogen donor molecule, occurred gelation in a variety of organic solvents. In the case of a 1:1 mixture of 1c and 4 in several solvents, each component independently caused gelation to give a simple mixture of different gels. Irradiation of the gel of 1a in 2-propanol decomposed gradually the gel into solution to give pinacol as a main product. Similarly, photoreaction of the 1:1 two-component gel of 1c and 4 in benzene afforded corresponding pinacol.

Fundamental Study on FRP Recycling using Several Solvent

The recycling of carbon fiber reinforced plastics (CFRP: including 37wt% of matrix epoxy resin) using tetralin (hydrogen donor solvent), decalin (nondonor solvent), alcohols and light cycle oil (LCO) was carried out in a small autoclave at 350-440°C with a reaction time of 1h under 2MPa of initial nitrogen atmosphere. For the reaction using tetralin, decalin and alcohols, the gaseous product was small of 0.2-4wt%, while the gaseous product increased to 9.4wt% using LCO. Conversion of resin varied with reaction temperature and solvent. Conversion of resin by the use of tetralin at 440°C showed more than 95wt% and enough tensile strength of recovered monofilament was observed.Similar high conversion and high grade quality of the recovered monofilament were also obtained by the use of cyclohexanol and other higher alcohols with sodium carbonate catalyst at 440°C. In these cases, phenol and alkylphenols were detected with 3.8-5.1wt%/CFRP (10.3-13.8wt%/resin) in the liquid product. This indicates that the degradation of thermosetting epoxy resin proceed effectively to produce monomer compounds with small gas production. However conversion of resin and tensile strength of the recovered monofilaments decreased at the lowering reaction temperature and the other solvent use.

Decomposition of a Multi-Peroxidic Compound: Triacetone Triperoxide (TATP)

The thermal decomposition of triacetone triperoxide (TATP) was investigated over the temperature range 151 to 230 °C and found to be first order out to a high degree of conversion. Arrhenius parameters were calculated: activation energy, 151 kJ/mol and pre-exponential factor, 3.75×1013 s−1. Under all conditions the principle decomposition products were acetone (about 2 mole per mole TATP in the gas-phase and 2.5–2.6 mole per mole in condensed-phase) and carbon dioxide. Minor products included some ascribed to reactions of methyl radical: ethane, methanol, 2-butanone, ethyl acetate; these increased at high temperature. Methyl acetate and acetic acid were also formed in the decomposition of neat TATP; the former was more evident in the gas-phase decompositions (151 °C and 230 °C) and the latter in the condensed-phase decompositions (151 °C). The decomposition of TATP in condensed-phase or in hydrogen-donating solvents enhanced acetone production, suppressed CO2 production, and slightly increased the rate constant (a factor of 2–3). All observations were interpreted in terms of decomposition pathways initiated by OO homolysis.

The Behavior of Free Radicals in Coal at Temperatures up to 300 °C in Various Organic Solvents, Using in Situ EPR Spectroscopy

In situ electron paramagnetic resonance (EPR) spectroscopy was used to investigate the behavior of free radicals in a lignite Banko coal (%C: 71.3%) that was heated to 300 °C at a rate of 10 °C/min in a hydrogen-donating solvent 1,4,5,8,9,10-hexahydroanthrancene (HHA), a polar solvent N-methyl-2-pyrrolidinone (NMP), and mixtures of the two solvents (NMP/HHA). With HHA, the radical intensity increased slightly as temperature increased from 60 to 200 °C, and then decreased greatly as it increased to 300 °C, due to the stabilization of radicals by hydrogen transferred from HHA. In contrast, the radical intensity in NMP increased greatly from 60 °C to 260 °C and then decreased slightly. NMP, an aprotic polar solvent, might interact with the free radicals and prevent the radical molecules from recombining and taking part in addition reactions. When NMP/HHA mixtures were used, changes in the radical intensity was dependent on the proportion of HHA. Moreover, the EPR spectra were deconvoluted to narrow and broa...

Hydrogen Transfer Cracking of Arabian Residua in Tetralin - I

Heavy Arabian vacuum residua were hydrocracked non-catalytically using tetralin as a hydrogen donor solvent. A bolted closure packless high temperature/high pressure autoclave with a magnedrive assembly was used batchwise for this purpose. The effects of temperature, pressure, and reactants ratio on the performance of the system were studied. The products were analyzed both qualitatively and quantitatively. Methods of analysis included: hydrocarbon group analysis using an HPLC, simulated distillation using a GC, sulfur determination and API gravity, asphaltene and carbon residue determination according to ASTM standards. Tetralin proved to be an effective donor for Arabian residua. HPLC and simulated distillation analysis showed that heavy compounds of the residuum were converted into lighter ones. When a ratio of tetralin to residuum less than 1/1 by weight was used coke formed in amounts proportional to tetralin. For ratios greater than 1/1 no coke formation was observed. A ratio of 2/1 was found to be a suitable ratio and was used in all runs. It was found that a minimum initial pressure of nitrogen gas (0.5 MPa) was sufficient to keep the reactants in the liquid state. Otherwise, pressure had no effect on the conversion. As the temperature was increased the conversion to lighter products increased. The relative percentage change of both asphaltenes and carbon residue increase with temperature. Degree of desulfurization also increased with temperature. This preliminary study was limited to use a maximum temperature of 435 °C. Increasing the temperature beyond this limit causes gas venting, and thus a loss of gaseous products. The system will be modified to work at higher temperatures by the method of rapid injection.

Coal liquefaction at early stage through a single reactor operation of the NEDOI process. A 1 t/d process supporting unit (PSU)

The 150-t/day NEDOL coal liquefaction pilot plant (PP) has validated the superior technical features with a highly active liquefaction catalyst and hydrogen donor solvent. The operation runs without any serious trouble and was successfully executed from March 1997 to September 1998. The results were integrated as a “technical package” and the R&D is transferred to a commercializing phase.

Effect of polystyrene addition on the monomer recycling of phenol novolac

The liquid-phase cracking of two different types of phenol novolacs, the precursors to commonly used crosslinked resins, was studied using a 200-ml autoclave at 430–450 °C under an initial nitrogen pressure of 2.0 MPa. Both phenol novolacs gave almost 100 wt.% conversion with a hydrogen-donor solvent (tetralin), and about 85 wt.% yield of oil product, including 43–76 wt.% of monomer compounds such as phenol and cresols. Phenol novolac containing >90 mol% of ortho–ortho and ortho–para bonds could be cracked in a non-hydrogen-donor solvent (decalin) with formation of only a small amount of coke. However, novolac containing >26 mol% of para–para bonds could not be degraded in decalin and produced a large amount of coke. When polystyrene was added to the latter novolac, an enhanced conversion of 51.1 and a 43.6 wt.% yield of distillable oil were obtained at 440 °C without a large amount of coke formation. Hydrogen gas at pressures >5 MPa also enhanced cracking reactivity.

Thermal reduction of 7H-benz[d,e]anthracen-7-one and related ketones under hydrogen-transfer conditions.

In the presence of hydrogen donor solvents and at elevated temperatures, aromatic ketones can be selectively deoxygenated to the corresponding hydroaromatic compounds. The kinetics for reduction of 7H-benz[d,e]anthracen-7-one (benzanthrone, 6) into 7H-benz[d,e]anthracene (benzanthrene, 1) in 9,10-dihydroanthracene (3) solvent has been investigated in detail. The relatively slow hydrogenation of 6 is due to reversibility of the initial hydrogen-transfer step according to a reverse radical disproportionation (RRD). The dynamics could well be rationalized using the energetics of species computed by density functional theory (DFT). The application of hydrogen donors such as 1 as a hydrogen-transfer agent, although favorable in terms of a low benzylic carbon-hydrogen bond dissociation enthalpy, is limited due to the slow self-hydrogenation, which in case of 1 gives 5,6-dihydro-4H-benz[d,e]anthracene (7).

Effect of solvent swelling on liquefaction of Xinglong coal at less severe conditions

Xinglong coal, a sub-bituminous coal, was swollen with pyridine or tetrahydrofuran followed by liquefaction in a 70-ml autoclave apparatus. The experiments were carried out to investigate the effects of temperature, solvent, atmosphere and catalyst on the liquefaction of solvent-swollen coal and untreated coal. The results indicate that the conversion of coal could be effectively improved in the temperature range of 320–420°C by swelling pretreatment. Molecular hydrogen shows no contribution to coal conversion during the liquefaction of pyridine-swollen coal in the absence of a catalyst and in the presence of hydrogen donor solvent such as tetralin. With the addition of a catalyst, the liquefaction conversion of pyridine-swollen coal is higher in H 2 than that in N 2. The swelling pretreatment of coal can improve the liquefaction yields, weaken the dependence of the process on the presence of molecular hydrogen and the hydrogen donation ability of the solvent, and increase the conversion of coal liquefaction.

00/00716 Operation researches of 150-t/d pilot plant for bituminous coal liquefaction

Operation of the 150 t/d NEDOL bituminous coal liquefaction pilot plant (PP) had started in March 1997. Three coal-in operations, a total of 134 days, were successfully completed. During the operations, performance of the process was evaluated, and a variety of engineering data was acquired. High-activated liquefaction catalyst (pyrite fine powder) and hydrogen-donor solvent resulted in high oil yield (58 wt% of dry, ash-free coal basis). Characteristics of the catalyst and recycle solvent in the 150 t/d PP will be presented in this report.

Outline of NEDOL coal liquefaction process development (pilot plant program)

The 150-t/day NEDOL coal liquefaction pilot plant (PP) has validated the superior technical features with a highly active liquefaction catalyst and hydrogen donor solvent. The operation runs without any serious trouble and was successfully executed from March 1997 to September 1998. The results were integrated as a “technical package” and the R&D is transferred to a commercializing phase.

Advances in the study of hydrogen transfer to model compounds for coal liquefaction

The advances in the study of hydrogen transfer to model compounds for coal liquefaction are reviewed. The results from many model reactions indicate that molecular hydrogen promotes thermolysis, hydrogenation, and hydrocracking of model compounds, whereas hydrogen-donating solvents inhibit the reactions. Unlike metallic catalysts such as Fe, Pd, and Ni, their sulfides catalyze radical hydrogen transfer to model compounds. The reactivities of model compounds toward hydrocracking depend not only on their hydrogen-accepting abilities, but also on their adsorption strength on catalyst surface and the stabilities of the resulting leaving groups.

Intramolecular homolytic displacements. Part 29: induced decompositions of 4,5-ethylenic peroxyketals

Thermolysis of a free radical initiator in solutions of hydrogen donor solvents such as cyclohexane, 1,4-dioxane and methyl isobutyrate, generated radicals by hydrogen abstraction of the solvent that were capable of adding to the unsaturated bond of 4,5-ethylenic peroxyketals. The adduct radical obtained led to 2-alkoxytetrahydrofuran by an SHi on the O–O bond.

Coal Dissolution by Heat Treatments in N-Methyl-2-pyrrolidinone, 1,4,5,8,9,10-Hexahydroanthracene, and Their Mixed Solvents: A Large Synergistic Effect of the Mixed Solvents

Heat treatments of coals of various ranks were carried out in a dipolar aprotic solvent of N-methyl-2-pyrrolidinone (NMP) and a strong hydrogen-donating solvent of 1,4,5,8,9,10-hexahydroanthracene (HHA) at 175−300 °C under N2 atmosphere. Dissolution yields were obtained using carbon disulfide/N-methyl-2-pyrrolidinone (CS2/NMP) mixed solvent (1:1 by volume) as an extraction solvent for the heat-treated coals. Considerable high dissolution yields were obtained for several coals even at temperatures as low as 175−300 °C. For the lower rank coals (C wt %, daf < 85 wt %) used, the dissolution yields in NMP and HHA increased with increasing temperature from 175 °C to 300 °C. The dissolution yields (38.2−78.1 wt %, daf) obtained in NMP were higher than those obtained in HHA. While, for Upper Freeport coal of higher rank (C% > 85 wt %, daf), a very high dissolution yield of 82.5 wt % was obtained in NMP at 175 °C, but it did not increase with increasing temperature to 300 °C and was lower than that in HHA. Similar results were observed for the other higher rank coal. NMP/HHA mixed solvents were found to show a large synergistic effect on the dissolution yields for all the coals used. An amount of 96.4 wt % of Banko coal was dissolved after the heat treatment in NMP/HHA mixed solvent (9/1 by weight) at 300 °C, which is much higher than 59.1 wt % in NMP and 44.5 wt % in HHA alone. It is also found that the extent of such synergistic effects is highly coal-rank-dependent. The mechanisms for the dissolution reaction in NMP, HHA, and NMP/HHA mixed solvents were discussed.

Lignin Depolymerization in Hydrogen-Donor Solvents

Summary The conversion of different types of lignin to monophenolic compounds has been studied between 500 and 650 K, under typical coal liquefaction conditions using 9,10-dihydroanthracene (AnH2) and 7H-benz[de]anthracene (BzH) as the hydrogen-donor solvents. The yield of phenolic compounds was found to increase with the capacity of the hydrogen donor. The application of a polar cosolvent appeared to be beneficial as well. The differences in product distribution could be related to the origin of lignin. The maximum yield amounted to 11 % after 4 h at 625 K using milled wood lignin in AnH2. It has been found that lignin itself is a hydrogen-donating substance and capable of cleaving aromatic ketones such as α-phenoxyacetophenone.

Liquefaction of sawdust for liquid fuel

Pressurized liquefaction of sawdust was carried out in an autoclave in the presence of solvent under cold hydrogen pressure ranging from 2.0 to 5.5 MPa at the temperature range of 150C–450°C. The reaction time varied from 5 to 30 min. Investigations were made on the effects of temperature, reaction time, cold hydrogen pressure and solvent on the liquefaction process. Results indicate that liquefaction of sawdust can start at a temperature of 200°C, much lower than that for coal in a hydrogen-donor solvent, e.g., tetralin which was used in this run of experiment. Oil yield increase with the rise either in temperature and in cold hydrogen pressure or with the longer reaction time.

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.

99/01888 Effect of precipitating some of the more intractable material from a hydrogen-donor solvent coal extract solution on its hydroprocessing behavior: Martin, S. C. et al. Energy Fuels, 1998, 12, (6), 1228–1234

99/01888 Effect of precipitating some of the more intractable material from a hydrogen-donor solvent coal extract solution on its hydroprocessing behavior: Martin, S. C. et al. Energy Fuels, 1998, 12, (6), 1228–1234

Upgrading of Alberta's Heavy Oils by Superacid-Catalyzed Hydrocracking

The HF.BF 3 superacid-catalyzed hydrocracking of tar sands bitumens and asphaltenes leads to deep-rooted chemical changes which affect both the aliphatic and aromatic constituents of the feedstocks even under mild experimental conditions, resulting in high yields of volatiles and liquid products. In contrast to conventional catalytic hydrocracking following free-radical mechanisms, the superacid-catalyzed reaction follows ionic mechanisms, yielding products very different from those following the free-radical reactions.When methylcyclohexane (MCH) is employed as a hydrogen-donor solvent, new products resulting from the oligomerization of MCH appear. MCH neat, without bitumen or asphaltene, does not oligomerize under identical conditions. These preliminary results point to the commercial potential of using the volatile HF.BF 3 superacid in the upgrading of bitumen and the oligomerization of cycloalkanes.