Non-donor Solvents Research Articles

Mechanism Studies of Coal Liquefaction in a Nondonor Solvent Using 14C-Labeled 1-Methylnaphthalene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism Studies of Coal Liquefaction in a Nondonor Solvent Using 14C-Labeled 1-MethylnaphthaleneBirbal Chawla, Hossein A. Dabbagh, and Burtron H. DavisCite this: Energy Fuels 1994, 8, 2, 355–359Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://doi.org/10.1021/ef00044a010RIGHTS & PERMISSIONSArticle Views73Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Deuterium incorporation during coal liquefaction in donor and nondonor solvents

Deuterium is selectively incorporated into the ring positions of 1-methylnaphthalene from gaseous deuterium, and the distribution of deuterium in the rings is essentially the same in the presence or absence of coal. Incorporation is under kinetic control. Ring exchange appears to be due to catalysis by the walls of the reactor. Incorporation in the methyl position does not occur to an appreciable extent at 385 or 450 °C in the absence of coal, but extensive incorporation does occur in the presence of coal. The pattern of ring substitution of deuterium precludes, or places severe restrictions on, the role of hydrogen shuttling by 1-methylnaphthalene as an explanation for the observation of higher coal conversion in this nondonor solvent than in a donor solvent, tetralin

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

CPMAS 13C NMR and pyrolysis-GC-MS studies of structure and liquefaction reactions of Montana subbituminous coal

This paper reports on the application of solid-state CPMAS 13C NMR and flash pyrolysis-GC-MS for characterization of the macromolecular network of a Montana subbituminous coal and its residues from temperature-programmed and non-programmed liquefaction (TPL and N-PL) at final temperatures ranging from 300 to 425°C in H-donor and non-donor solvents. The combined use of 13C NMR and Py-GC-MS revealed that this coal contains significant quantities of oxygen-bearing structures, corresponding to about 18 O-bound C per 100 C atoms and one O-bound C per every five to six aromatic C's. The oxygen-bearing components in the coal include catechol-like structures, which seem to disappear from the liquefaction residues above 300°C; carboxyl groups, which almost disappear after 350°C; and phenolic structures, which are most important in the original coal but diminish in concentration with increasing temperature. These results point to the progressive loss of oxygen functional groups and aliphatic-rich species from the macromolecular network of the coal during programmed heat-up under TPL conditions. The higher conversions in TPL runs in H-donor tetralin (relative to the conventional N-PL runs) suggest that the removal of carboxylic and catechol groups from the coal and the capping of the reactive sites by H-transfer from H-donors at low temperatures (≤350°C) have contributed to minimizing the retrogressive crosslinking at higher temperatures. Quantitative calculation of NMR data and mathematical correlation were also attempted in this work. For 24 liquefaction residues derived under significantly different conditions, linear correlations between C-distribution and reaction temperature (≥ 300°C) have been found, which can be expressed by a simple equation, C i = αf i + βT, where f i and C i, represent content of aromatic, aliphatic, or oxygen-bound carbons in the original coal and residue, respectively; T stands for the reaction temperature; α and β are constants.

Effect of solvents on thermal cracking of model compounds typical of coal

Conversions of bibenzyl and dibenzyl ether as coal models depend on the nature of the solvent. When solvents that were poor hydrogen donors, but their dehydrogenated radicals were more stable than donors, were used, bibenzyl and dibenzyl ether conversion were markedly enhanced. Positive effects wee observed by the mixing of tetralin with nondonor solvents. However, negative effects by such mixing were observed in the case of dibenzyl ether. In this paper, the importance of radical-induced decomposition on cracking of coal model compounds is suggested.

Roles of nondonor solvent in the hydrogen-transferring liquefaction of Australian brown coal

Roles of nondonor solvent in the hydrogen-transferring liquefaction of Australian brown coal

Perkin communications. 4,4′-Dimethoxytrityl and 4-monomethoxytrityl tetrafluoroborate: convenient reagents for the protection of primary alcohols including sugars

In a non-donor solvent (e.g. acetonitrile) and in the presence of 2,6-di-t-butyl-4-methylpyridine, the readily prepared 4-methoxytrityl tetrafluoroborate (3) and 4,4′-dimethoxytrityl tetrafluoroborate (2) are highly effective reagents for the methoxytritylation and dimethoxytritylation, respectively, of primary alcohols including sugars.

Synthesis and reactivity of titanium/cobalt complexes with Ti-O-C-Co bridges

Reactions between titanium metallocene dicarbonyls and dicobalt octacarbonyl were investigated and found to give a variety of Ti/Co complexes depending on the reaction conditions. Reaction between Cp 2 Ti(CO) 2 and Co 2 (CO) 8 in nondonor solvents led to the formation of the known Cp 2 Ti[OCCo 3 (CO) 9 ] 2 via a novel redox/cluster-building process

Direct liquefaction of hydrolytic eucalyptus lignin in the presence of sulphided iron catalysts

The liquefaction of hydrolytic eucalyptus lignin has been studied in hydrogen donor and non-donor solvents in the presence of ferrocene and of ferrocene associated with sulphur or carbon disulphide. With the exception of tetralin, all reactions were carried out at supercritical conditions of the solvent. It was found that the yields of heavy oils increase significantly with the increase in hydrogen pressure in the non-donor solvents. The oil yields also increase with the density of the solvent but level out at densities higher than 0.30 g/ml. The consumption of molecular hydrogen is significant in the non-donor solvents; in the donor solvents the hydrogen is mostly transferred from the solvent itself. In the non-donor solvents, the oil yields depend strongly on the efficiency of the catalyst, but not in the donor solvents.

Synthesis, structure and properties of mononuclear and dinuclear molybdenum(III) bromide compounds. Ligand-induced, reversible breakage of a metal-metal bond in Mo 2Br 6(dppe) 2

MoBr 3(THF) 3 reacts with 1 equivalent of bis(diphenylphosphino)ethane (dppe) in THF to yield MoBr 3(dppe)(THF) ( 1). The THF ligand in the latter molecule can be easily replaced by MeCN to afford MoBr 3(dppe)(MeCN) ( 2). When treated in a non-donor solvent, 1 loses THF and dimerizes to one of two isomeric Mo 2Br 6(dppe) 2 molecules (green, 3, kinetic product; purple, 4, thermodynamic product) depending on experimental conditions. An X-ray analysis of 4 shows an edge-sharing bioctahedral structure and the presence of a MoMo bond. Both 3 and 4 can be reconverted to the parent compound 1 by warming in the presence of excess THF. Compound 2 can also be transformed into the dinuclear compound 4.

The influence of hydrogen donors on the pyrolysis of a bituminous coal as studied by in situ e.s.r. spectroscopy

The effect of hydrogen gas, a hydrogen donor solvent (tetralin) and a non-donor solvent (decane) on the pyrolysis (to 500 °C) of a bituminous coal, before and after extraction with chloroform, has been studied by in situ e.s.r. in a flowing gas cell at atmospheric pressure. It was found that hydrogen gas at 1 bar had an insignificant effect on the course of the reaction, as determined by free radical population measurements, compared with nitrogen gas. In contrast, both tetralin and decane change the free radical populations developed during pyrolysis, and the extent of the induced change varies upon chloroform extraction of the coal. These results are discussed with reference to current coal liquefaction models, and are interpreted in terms of the chemical and physical interactions of the solvent with the coal.

Effects of Lewis acids and bases on the carbotitanation of unsaturated hydrocarbons and ketones with η 3-allyl(di-η 5-cyclopentadienyl)titanium(III)

The carbotitanating action of η 3-allyl(di-η 5-cyclopentadienyl)titanium(III) toward ethylene and other unsaturated hydrocarbons, such as trimethyl(phenylethynyl)silane, and toward ketones has been shown to be promoted by Lewis acids strong enough to polarize the carbon-titanium bond, yet not so strong as to exchange the carbon group for halogen. Of the trio of acids, Me 3Al, Me 2AlCl and MeAlCl 2, only Me 2AlCl is able to activate the carbon-titanium bond and thus to promote the polymerization of ethylene and the carbotitanation of the phenylethynylsilane. Evidence is adduced that the activated reagent in both reactions is the complex, Cp 2Ti(allyl)-Me 2AlCl. By contrast, the carbotitanating activity of this complex is completely destroyed by addition of a Lewis base, such as THF. Towards ketones, the Cp 2Ti(allyl) reagent can behave either as a carbotitanating agent or as a reducing agent. Which of these reactions is favored again depends upon the presence or absence of Lewis acids and bases. With Lewis acids or in non-donor solvents the Cp 2Ti(allyl) reagent effects the addition of the allyl-titanium bond to the carbonyl group. On the other hand, in the presence of Lewis bases, such as THF, Cp 2Ti(allyl) causes the bimolecular reduction or monomolecular reduction of the ketone to yield the glycol or secondary alcohol. The significance of these results to polymerization mechanisms and to organic synthetic applications is briefly discussed.

Some reactions of phenylene-and polyphenylene-mercurials

Summary Cleavage reactions of six phenylene- and polyphenylene-mercury heterocycles with the mercuric halides and mercuric acetate in suitable refluxing solvents readily produce 1,2-C 6 X 4 (HgX) 2 ; 2,2′-C 6 H 4 C 6 H 4 (HgX) 2 and 2,2″-C 6 H 4 C 6 H 4 C 6 H 4 (HgX) 2 (X = Cl, Br, I or CH 3 CO 2 ). Addition of silver acetate to 2,2′-C 6 H 4 C 6 H 4 (HgBr) 2 gives 2,2′-C 6 H 4 C 6 H 4 (HgO 2 CCH 3 ) 2 which reacts with concentrated hydrochloric acid to form 2,2′-C 6 H 4 C 6 H 4 (HgCl) 2 . Treatment with sodium iodide, or in some cases simply the application of heat under vacuum, causes symmetrization of these cleavage products back to the original heterocycles in high yield. The terphenylenemercury dimer, (C 6 H 4 C 6 H 4 C 6 Hg) 2 , forms solvates with a wide variety of donor and non-donor solvents. Pyrolysis of mercuric 2,3,4,5-tetrafluorobenzoate at 190°C yields 2-mercurio-3,4,5,6-tetrafluorobenzoate and 2,3,4,5-tetrafluorobenzoic acid; at 300°C the former gives tetrafluorophenylenemercury, (C 6 F 4 Hg) 3 .

Catalytic hydroliquefaction of coal : about the methodology in batch experiments

The results of catalytic hyroliquefaction under batch conditions depend on a large number of variables. The present results concern a few of these variables, in particular the influence of the catalyst concentration, of the mode of sulfidation or(and) of introduction of the catalyst in the coal/solvent mixture, and of the nature of the model compound solvent. Our results indicate that increasing the concentration of catalyst increases the conversion of coal into toluene soluble products and the hydrogen consumption but has a small effect on oil formation. An inhibition of the first fractions of a NiMo/A1203 catalyst added is shown. Strong effects of the sulfiding mode of an iron oxide catalyst, and of the temperature of introduction of the iron oxide into the autoclave are observed relative to the hydrogenation activity of the iron catalyst, when at the same time there is no influence on coal conversions. The replacement of tetralin by a non-donor solvent, 1-methyl naphthalene, suggests that the direct hydrogen transfer process from molecular hydrogen to coal fragment radicals on the catalyst surface may be important.

Low temperature—long time, high temperature-short time liquefaction of coal: The Hokudai process

A Japanese cola was hydrogenated in wash oil with fine iron dust and sulphur as catalyst under a reaction pressure of 12–13 MPa at 420 °C for 2 h and then at 500 °C for 0–20 min. The liquid yield boiling up to 600 °C amounted to 55–66 wt%. Pyridine conversion was ≈ 100 wt%, benzene conversion 82–90 wt% and n-hexane conversion 53–70 wt%. Compared with direct hydrogenation at 500 °C for 10 min the low temperature-long time plus high temperature-short time liquefaction process (the Hokudai process) is a very effective method for obtaining high liquid yield under relatively low hydrogen pressure without coking, using disposable catalyst and non-donor solvent.

The effect of the solvent in stannous chloride catalysed hydrogenation of coal

Hydrogenation of the same coal in an autoclave using stannous chloride as the catalyst was carried out with donor and non-donor solvents and without solvent at 400° and 450°C. The conversion, product distribution and chemical nature of the oil and asphaltene were very similar with donor and non-donor solvents. However, in the absence of solvent the conversion and the liquid yield were lower, the gas yield higher and the liquid product was more aromatic. At 450°C the gas yield was higher, the asphaltene yield lower and both the oil and asphaltene were more aromatic than at 400°C, both with and without solvent. A possible explanation for the effect of solvent is given.

Solution studies of the asymmetric hydrogenation catalyst system derived from the [rhodium (1,2-bis(diphenylphosphino)-1-cyclohexylethane)] moiety

A solution 31P NMR study of the asymmetric hydrogenation catalyst derived from the [rhodium(1,2-bis(diphenylphosphino)-1-cyclohexylethane)] system was initiated to gain further insight into the solution chemistry of this catalyst. In polar, weakly coordinating solvents, the solution behavior is similar to that of previously studied hydrogenation catalysts. However, since this ligand imparts enhanced solubilities to the cationic rhodium complexes, it was possible to study the catalytic intermediates in non-donor solvents such as CH 2Cl 2. When the catalyst precursor complex [Rh(norbornadiene)-(Cycphos)](PF 6) is hydrogenated in CH 2Cl 2, a dimeric structure results. The 31P NMR of this complex formed in CD 2Cl 2 is complex and is interpreted as a mixture of different isomeric dimeric complexes. When the dimeric complex [Rh(Cycphos)] 2(PF 6) 2 is isolated as a crystalline solid and redissolved in CD 2Cl 2, the resultant 31P NMR spectrum is unusual. The spectrum is interpreted as arising from a single dimeric isomer showing novel long-range, non-bonded RhP couplings. This result and its implications to the mechanism of action of these chiral catalysts is discussed.

Stereochemistry of Bis[N-(2,6-diisopropylphenyl)salicylideneaminato]cobalt(II) Complexes

Abstract The compounds bis[N-(2,6-diisopropylphenyl)salicylideneaminato]cobalt(II) and analogous species with substituents at the 5-position of the salicyl moiety have been synthesized. They prefer the tetra-coordinate tetrahedral geometry in non-donor solvents, while some of them are forced into planar structures in the solid state. In pyridine, exclusively predominant species are five-coordinate complexes with the base bound with the cobalt(II) ion. Monopyridine adducts, which consist of five-coordinate complexes, have been isolated as crystals.

NICKEL(II) COMPLEXES EMPLOYING BIDENTATE LIGANDS DERIVED FROM 2-(β-KETOALKYL) HETEROAROMATIC COMPOUNDS

Abstract Ni(L)2 complexes, where L equals 2-(trifluoroacetyl) heteroaromatic anion have been prepared and characterized. 2-(Trifluoroacetyl)-picolinato anion (TFAP) gives a Ni(L)2 complex that appears to be a dimeric 5-coordinate square pyramid. The complexes Ni(4MeTFAP)2 and Ni(5MeTFAP)2 are square planar complexes while Ni(6Me-TFAP)2 is tetrahedral due to steric interference. In non-donor solvents, the complexes Ni(TFAP)2, Ni(4MeTFAP)2 and Ni(5MeTFAP)2 exhibit properties that indicate a polymer/monomer equilibrium. Ni(L)2 complexes undergo a unique gas-solid dissociation reaction with H2O and NH3 to give coordinated NH2 − and OH−.

The Effect of Steric Condition on the Structure of Cobalt(II), Nickel(II), and Copper(II) Complexes with Schiff Bases Obtained from Salicylaldehyde Derivatives and 9-Aminofluorene

Abstract Cobalt(II), nickel(II), and copper(II) complexes with N-(9-fluorenyl)salicylideneaminates (abbreviated as X-sal-fl) have been examined in relation to the effect of steric condition on the structure of the metal complexes. Compounds of the type M(X-sal-fl)2 and their pyridine adducts were isolated as crystals. Complexes of the type Cu(X-sal-fl)Cl were also obtained. Both in the solid state and in non-donor solvents, the complexes Co(X-sal-fl)2 have a tetrahedral configuration, and Ni(X-sal-fl)2 and Cu(X-sal-fl)2 have a square-planar configuration. Possible structures of the pyridine adducts are discussed. The results indicate that the steric hindrance caused by fluorenyl is greater than that by diphenylmethyl.