Aluminium bromide catalysed transalkylations of a Texas lignite coal

Texas lignite coal was treated at a variety of reaction times and temperatures with water-activated AlBr₃ in the presence of either m-xylene or diphenyl ether. Reactions with m-xylene resulted in increases in coal weights, probably due to incorporation of xylene into the coal structure, whereas reactions with diphenyl ether resulted in weight losses in the treated coal. The solubility in pyridine of the coal recovered from these reactions was increased significantly, reaching a maximum of 50% in one reaction with diphenyl ether. Suggestions are made for processes that may explain both the weight increases and the greater pyridine solubility. Support for the occurrence of transalkylation of alkyl groups from lignite to diphenyl ether was provided by g.c.-m.s. analysis of an ether extract in which diphenyl ether molecules substituted with C₁–C₁₃ alkyl groups could be identified. Also of interest was the observation of the compound phenoxathin among the products of transalkylation.     

Alkyl aryl ethers in lignite solubilization: 2. Analysis of oil fractions

The FT-i.r. and ¹H n.m.r. spectroscopic analyses of oils or maltenes from a Spanish lignite (Utrillas, Teruel), are reported. These oils were obtained by depolymerization with alkyl aromatic ethers (anisole, 3-methylanisoleand 1,3-dimethoxybenzene) catalyzed by Lewis acids ZnCl₂, AlCl₃, SbCl₃and BF₃ (as boron trifluoride etherate), at atmospheric pressure and temperatures <220 °C. Bands due to aromatic ethers in the i.r. and n.m.r. spectra of the oils obtained by depolymerization indicate solvent incorporation. Oils obtained by direct lignite extraction showed 25% aromatic H and some H_α (≈3%) without OH groups. These appeared in some oils obtained by depolymerization with AlCl₃ and were due to secondary reactions with the aromatic extract. Oils derived from processes with good yields showed increases in aromaticity. The extent of substitution of aromatic rings in oils obtained by depolymerization was less than for oils directly extracted. All the oils studied show a low degree of condensation.     

The composition of the bases in a supercritical gas extract

Average structure data for the basic fraction from a supercritical toluene extract of Liddell coal are reported based on ¹³C- and ¹H-n.m.r. spectroscopy combined with elemental, functional group and molecular weight analyses. This data indicated an average aromatic ring size of two condensed rings with about a third of the possible aromatic sites substituted. The ¹³C-n.m.r. spectrum showed the presence of unsubstituted alkyl chains >C₈. A number of nitrogen heterocycles, ranging from one to five condensed rings, were identified by g.c.-m.s. and fluorescence and spectroscopy.     

Wettability modification of lignite by adsorption of alkyltrimethylammonium bromides with different alkyl chain length

To overcome the problem of moisture re-adsorption of dried lignite with common evaporation drying methods, a set of linear alkyl quaternary ammonium surfactants (C₁₀TAB, C₁₂TAB, and C₁₆TAB) were used to modify lignite surface, and the effects of alkyl chain length on the adsorption characteristics of surfactants and wettability of lignite surface were evaluated. Pseudo-first and pseudo-second-order kinetic models and Langmuir model were, respectively, used to simulate adsorption kinetics and adsorption isotherms. The results showed that three surfactants gradually formed double-layer adsorption on lignite surface and the loading of surfactant increased with the length of alkyl chain. X-ray photoelectron spectroscopy analysis showed that C₃H₉N⁺ moiety of the surfactants would preferentially interact with O?C?O groups of lignite. Results of wetting heating and moisture re-adsorption showed that three surfactants obviously decreased hydrophilicity and restrained moisture re-adsorption of lignite, but with the formation of double-layer adsorption, hydrophilic headgroups of surfactant faced outward, which caused increase in hydrophilicity of lignite. As a result of two opposite effects of surfactant chain length on lignite wettability, the effect of C₁₂TAB on decreasing hydrophilicity was the best among the three chosen surfactants.     

Identification of straight-chain fatty acids associated with metallic cations in coals

Straight-chain fatty acids and associated cations, such as Ca²⁺, Mg²⁺ and Fe³⁺, in the solvent extracts from the humic substances of Joban lignite and Taiheiyo coal were analysed after treatment with hydrochloric acid. Gas chromatographic analyses showed the most abundant presence of C₁₆ in the C₁₄ to C₃₂ straight-chain fatty acids. The amount of Ca²⁺ bonded to the fatty acids was calculated to be about 20 ppm of the humic substances.     

Comparison of the chemical structure of coal hydrogenation products,athabasca tar sand bitumen and Green River shale oil

Coal hydrogenation products, Athabasca tar sand bitumen, and Green River shale oil produced by retorting were analyzed by the Brown—Ladner method and the Takeya et al. method on the basis of elemental analysis and ¹H-NMR data, by ¹³C-NMR spectroscopy and by FT-IR spectroscopy. Structural characteristics were compared.The results show that the chemical structure of oils from Green River shale oil and Athabasca tar sand bitumen, and the oils produced in the initial stage of hydrogenation of Taiheiyo coal and Clear Creek, Utah, coal is characterized as monomers consisting of units of one aromatic ring substituted highly with C_3–6 aliphatic chains and heteroatom-containing functional groups. The chemical structure of asphaltenes from Green River shale oil and Athabasca tar sand bitumen is characterized by oligomers consisting of units of 1–2 aromatic rings substituted highly with C_3–5 aliphatic chains and heteroatom-containing functional groups. The chemical structure of asphaltenes from coal hydrogenation is characterized by dimers and/or trimers of unit structures of 2 to 5 condensed aromatic rings, substituted moderately with C_2–5 aliphatic chains and heteroatom-containing functional groups.The close agreement between fa(¹H-NMR) and fa(¹³C-NMR) for Green River shale oil derivatives and Athabasca tar sand derivatives indicates that the assumption of 2 for the atomic H/C ratio of aliphatic structures is reasonable. For coal hydrogenation products, a value of 1.6–1.7 for the H/C ratio of aliphatic structures would be more reasonable.     

Alkylation of mixed micro‐ and nanocellulose to improve dispersion in polylactide

Nanocellulose tends to be aggregated due to the hydrogen bonding between three of the hydroxyl groups in each repeat unit, resulting in poor dispersion in non‐polar polymer matrices. In this research, to improve the dispersion of cellulose particles in a polymer matrix, a long hydrophobic alkyl chain was substituted for hydrogen in the hydroxyl group of cellulose via a bimolecular nucleophilic substitution (S_N2) reaction with alkyl bromide. Octyl (? C₈H₁₇) and dodecyl (? C₁₂H₂₅) groups were applied in this reaction, which is faster and simpler than other substitution reactions. The chemical structures of octyl and dodecyl ether cellulose were identified using Fourier transform infrared and NMR analyses. The contact angle with water and methylene iodide was measured to calculate the surface energy of alkyl nanocellulose. The surface energy was decreased by the substituted alkyl chain. The thermal properties, morphology and crystal structure of octyl and dodecyl ether cellulose were also investigated to determine the possibility of use as a reinforcement. Furthermore, polylactide/alkyl ether cellulose composites were prepared to make certain of sufficient dispersion of the alkyl ether cellulose in the polylactide matrix. The thermal and mechanical properties of the polylactide composite films were investigated. The optical transmittance of the polylactide composites was measured to confirm the relative dispersity. © 2014 Society of Chemical Industry     

Correlation of chemical constitution and boiling point with separation behaviour during distillation of coal liquid

The separation behaviour of coal hydrogenation liquids during distillation was clarified using correlations between chemical structural factors (R_a, R_n and C_al) and boiling points of narrow cut distillation fractions. The separation order according to chemical structure at given distillation temperatures was represented on a three-dimensional R_aR_nC_al diagram. In this diagram, one axis represents the number of aromatic rings in the structure of a compound (R_a), one represents the number of naphthenic rings (R_n), and the third axis represents the number of alkyl carbons (C_al). This diagram is believed to be an appropriate way to handle the analysis of molecules in coal liquids, which are extremely complicated mixtures. Kerosene, light oil and heavy oil from coal liquid were also characterized on this diagram. The distribution ranges of components during separation in distillation agree fairly well with their corresponding distillation temperature range on the R_a R_nC_al diagram proposed. The distillation curve was predicted from the structural analyses with h.p.l.c./g.c.-m.s. and constitution-boiling point correlation as shown in the R_aR_nC_al diagram.     

An h.p.l.e. and m.s. analysis of distillate fractions of neutral oil from hydrogenated Akabira coal to elucidate chemical structures

Akabira coal-derived neutral oil was separated into 25 narrow boiling range fractions covering 183–423 °C, and subsequently separated into compound class fractions : alkanes, monoaromatics, naphthalene-type diaromatics, fluorene-type diaromatics and tri- and/or tetraaromatics, by high performance liquid chromatography (h.p.l.c.). The compound type analyses of the distillate/h.p.l.c. fractions were performed using electron impact mass spectroscopy (e.i.m.s.) or field ionization mass spectroscopy (f.i.m.s.). Aromatic/hydroaromatic compound types and the alkyl side-chain carbon distribution of the distillate/h.p.l.c. fractions were clarified, based on the separation behaviour of h.p.l.c. and the type analyses according to Z value by m.s. By the distillation/h.p.l.c./m.s. method, coal-derived oil was characterized in terms of the distribution of the numbers of aromatic rings, naphthenic rings and carbons of alkyl groups attached to these rings. The variations in chemical structure in a compound class with distillation temperature are discussed in terms of these chemical structural factors.     

Semicoking of Kansko-Achinsk lignite and applications of tar fractions

The semicoking of regular lignite from the Berezovsk field in Kansko-Achinsk Basin (moisture content 1.6–19.6 wt %) at 450–550°C in a reactor with solid heat carrier is studied. The products are semicoke (up to 68.1%), tar (up to 9.5%), gas (up to 31.9%), and pyrogenetic water. The composition of the semicoking gas is quantitatively determined. Its main components are hydrogen (up to 71.7%) and methane (up to 17.2%). The heat of combustion of the semicoking gas is 12.39–16.25 MJ/m³. The yield of phenolic fractions in the semicoking tar, consisting of phenol and its alkyl derivatives with one or two short substituents (C₁–C₃), is 10.5–14.6%. After hydraulic purification of the gasoline fraction in the semicoking tar (below 180°C), gasoline with octane rating 75.8 (by the motor method) is obtained. It consists of aromatic, saturated, and unsaturated hydrocarbons (C₅–C₈). The diesel fuel derived from tar fractions distilled off at temperatures up to 350°C are of good quality, except for their low cetane rating. The high-boiling tar fractions may be used to produce lignite pitch and pitch coke. The semicoke obtained is a very effective reducing agent in the production of phosphorus. It may also be used as a lean additive in coking batch and as a component in enriched domestic coal briquets.     

Group structure characteristics of the liquid thermolysis products of vitrinites of different ranks

The results of the group structure analysis of asphaltenes, resins, and hydrocarbons in the liquid products obtained upon the thermolysis of vitrinites of different ranks are presented. The molecular weights of components decreased with the degree of vitrinite conversion: aromatic structures were predominant among ring compounds, and the lengths of alkyl substituents decreased. The molecules of asphaltenes predominantly consisted of two-block structures, whereas tars and oils mainly exhibited a single-block organization; in all cases, the alkyl substituents of aromatic rings had a length of C₁–C₄.     

Color improvment of C9 hydrocarbon resin by hydrogenation over 2% Pd/γ‐alumina catalyst: Effect of degree of aromatic rings hydrogenation

Color improvement of commercial C₉ hydrocarbon resin (c‐C₉HR) and prepared C₉ hydrocarbon resin (p‐C₉HR) has been investigated under various hydrogenation conditions over 2% Pd/γ‐alumina catalysts. The degrees of aromatic rings hydrogenation (DHs) and molecular structure of resin were determined from nuclear magnetic resonance of ¹H and ¹³C (¹H‐NMR and ¹³C‐NMR) and Fourier transform infrared spectroscopy (FTIR) analyses. The starting c‐C₉HR presented in yellow color (Gardner color No. 8.4). Under the hydrogenation conditions used (H₂ pressure 70 bar, 250°C, and 8 h), the ethylenic proton in c‐C₉HR was completely removed, but the aromatic rings content remained unaltered and very little change in resin color was observed (Gardner color No.8.1). On the other hand, the starting p‐C₉HR contained only unsaturated aromatic proton with Gardner color No.17.1. Under similar conditions, aromatic rings in p‐C₉HR were converted to alicyclic rings, and its color was reduced to Gardner color No.5.7. By varying the DH of aromatics in p‐C₉HR, two‐step decolorization was observed in which at lower DH (≤10%) the color decreased sharply from 17.1 to 9.3, while further color reduction to 5.7 was obtained when the DH was increased to 94%. It is suggested that both color body and aromatic rings were the main sources contributing to C₉HR color. Nevertheless, color stability of the resin during heat treatment was significantly improved by hydrogenation especially at DH ≥ 50%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Analysis of coal-derived liquid obtained by mild hydrogenation: 1. Neutral oil distilling at 186–343 °C

Taiheiyo coal (77% C) was hydrogenated under mild conditions to preserve the unit structure of the parent coal as far as possible. The n-hexane-solubles (yield, 49.8 wt% daf coal) were washed with acid and base and the neutral material separated into 7 fractions by vacuum distillation. The three lower boiling fractions, DS01 (7.3 wt% neutral oil), DS02 (3.6 wt%) and DS03 (4.8 wt%), were further separated by liquid chromatography into hydrocarbon subfractions which were analysed by g.c. and g.c.-m.s. Saturates are most abundant, especially the n-alkanes which comprise ≈9–13 wt% of each fraction. The saturates also contain isoprenoids (C₁₅, C₁₆, C₁₈, C₁₉ and C₂₀), branched alkanes, n-alkyl cyclohexanes, terpanes and others. With increasing boiling point, smaller amounts of monoaromatic ring hydrocarbons and more di- or triaromatic ring hydrocarbons are found. The alkyl side-chains of aromatic nuclei have a large carbon number, especially in the smaller rings. The existence of phenyltetralin or phenylnaphthalene shows a feature of bonding between aromatic nuclei.     

The chemical nature of material released from coal-derived asphaltenes by reprecipitation and cyclohexane extraction

The yields and chemical nature of n-pentane solubles released from three coal-extract asphaltenes by reprecipitation with n-pentane and cyclohexane extraction have been investigated. With increasing concentration of n-pentane solubles in the original coal liquid, the yield of oils obtained by reprecipitation increases, as also does the tendency for their structures to resemble those of the original n-pentane solubles. No alkanes below C₄₀ were released from the asphaltenes by extraction with cyclohexane and therefore the long alkyl chains (10% of the total carbon in the lignite asphaltenes) must be bound to aromatic, carboxyl or heteroatomic groups.     

Chemical structure of heavy oil from coal hydrogenation 1. Hydrogenation with zinc chloride catalyst

Oil product from the hydrogenolysis of a high-volatile bituminous coal was separated by solubility, fractionated by gel permeation chromotography and characterized by structural analysis. The average structural unit in the hexane-soluble, aromatic oil fraction consists of 1–3 aromatic rings with 0.3-0.5 of the ring carbons substituted by alkyl groups and oxygen containing groups. Molecular weights vary from 200 to 500. The larger molecular weight fractions have longer alkyl chains and lower carbon aromaticities. The molecules are mainly of single unit structures. The average structural units in asphaltene fractions contain from 2.5-4 aromatic rings, are of higher carbon aromaticities and contain shorter alkyl groups. The asphaltene molecules consist of two or more structural units, crosslinked together, and have molecular weights of 300–1400. The oxygen content of the fractions decreases with decreasing molecular weight. Increasing the amount of ZnCl₂ catalyst during hydrogenolysis resylts in an increased yield of lower-molecular-weight material, but no change in the structural properties of the product. This is interpreted to mean that ZnCl₂ is active in the scission of covalent bonds between structural units during liquefaction and that the hydrogenolysis reaction is mostly cleavage of crosslinks between structural units with minimal reaction of the units themselves.     

Study of structural parameters on some petroleum aromatic fractions by 1H n.m.r./i.r. and 13C, 1H n.m.r. spectroscopy

¹H n.m.r. and i.r. spectroscopy were used to derive molecular parameters of petroleum fractions. Relative amounts are estimated of methylene and methyl groups in substituted alkyl side chains bonded to the aromatic ring system. The resolution of equation combinations leads to estimation of $\text{H}{}_{\mathrm{s}}\text{C}{}_{\mathrm{s}}\text{(=x)}$, which is an important parameter for structural analysis. Several petroleum fractions were characterized in terms of hypothetical average molecular structures using ¹H n.m.r./i.r. procedures, ¹³C coupled proton n.m.r. and Brown—Ladner methods. It is proposed that the ¹H n.m.r./i.r. method gives more precise average molecular parameters than the Brown-Ladner method with the most precise analytical procedure, up to date, being ¹³C coupled proton n.m.r. analysis. The Brown-Ladner method is especially suitable for structural analysis of low aromaticity molecular structures with long straight-chain alkyl substituents.     

Polymerization of alkyl acrylates and alkyl methacrylates with starch

A series of C₄-C₁₂ alkyl acrylates and methacrylates was polymerized with starch by irradiating starch–monomer mixtures with ⁶⁰Co. Homopolymers were extracted with cyclohexane. The amounts of insoluble versus soluble synthetic polymer in polymerization run with alkyl acrylates varied less with the chain length of the alkyl substuent than in the polymerizations run with alkyl acrylates varied less with the chain length of the alkyl substituent than in the polymerizations run with alkyl methacrylates; and the poly(alkyl acrylate) contents of cyclohexane-insoluble fractions were all in the 38–45% range. Synthetic polymer contents of the products from butyl, hexyl, and decyl methacrylates were also close to this range. Octyl and lauryl methacrylate, however, gave high conversions to cyclohexane-soluble poly(alkyl methacrylate) along with little or no unextractable synthetic polymer in the starch-containing fractions. Poly(lauryl methacrylate) could be rendered insoluble by incorporating a small amount of tetramethylene glycol dimethacrylate in the polymerization mixture. In a series of polymerizations run with hexyl acrylate and hexyl methacrylate, lower irradiation doses led to more cyclohexane-soluble polymer and less synthetic polymer in the starch-containing fractions. Enzymatic digestion of starch-soluble polymer and less synthetic polymer in the starch-containing fractions. Enzymatic digestion of starch-containing polymers gave synthetic polymer fractions that were largely insoluble in cyclohexane. Crosslinking is, therefore, probably taking place during these polymerizations; however, we could not eliminate the possibility that reduced solubility was caused by small amounts of residual carbohydrate in these polymer fractions. Ceric ammonium nitrate-initiated polymerizations of butyl acrylate, hexyl acrylate, and butyl methacrylate with starch gave cyclohexane-insoluble polymers that contained 33–39% synthetic polymer. The higher alkyl acrylates and methacrylates produced little or no polymer under these conditions. Starch-containing fractions were tested as absorbents for hydrocarbons. Products prepared from decyl acrylate and lauryl acryle acrylate absorbed about 9 g of isooctane per 1 g of polymer, whereas the lowrer alkyl monomers gave polymers with lower absorbency.     

Aliphatic hydrocarbons in a low-temperature tar

The total aliphatic hydrocarbons from a low-temperature tar were separated into four groups, each consisting of a similarly wide range of molecules (approximate boiling range of each, 175°–500°): (a) n-alkanes; (b) branched-chain alkanes and cycloalkanes; (c) straight-chain alkenes; and (d) branched-chain alkenes and cycloalkenes. In (a), n-alkanes, and in (c), alk-1-enes, trans-alk-2-enes and cis-alk-2-enes from C₁₀ to C₃₇ were identified and quantitatively estimated. Group (b) contained pristane and phytane among the few predominant branched-chain species present, and molecules with isopropyl groups and single and condensed saturated rings. Group (d) was predominantly mono-olefinic, the double bonds probably being in the terminal position in alkyl chains; isopropyl groups were also present.     

A 13C n.m.r. study of the sulphonation of novolacs

A parameter scheme has been devised for predicting the ¹³C shifts of atoms in the aromatic rings of phenols substituted with SO^?₃, CH₂Ar and CH₃ in an alkaline medium, from the measured shifts of 30 different substituted benzene rings. The application of the scheme to novolacs is considered before the scheme is used to interpret the changes of chemical shift that occur upon sulphonation of one such sample. In the aromatic carbon region the sites of substitution on the rings are identified. In the upfield region of the spectrum a substantial alteration to the pattern of shifts from the bridging methylene groups was noted: once a ring had been sulphonated the methylene bridge might break to yield methylol groups, which then to a large extent reformed as methylene and dimethylene ether (CH₂OCH₂) links, but with an increased proportion of abutments on sites para with respect to the phenolic group.     

Reactivity of poly(chlorotrifluoroethylene) (PCTFE) oil and PCTFE derivatives with phenyllithium and phenyl Grignard reagents

Summary Poly(chlorotrifluoroethylene) (PCTFE) oil upon reaction with phenyllithium at-78°C formed functionalized products that could be isolated in three fractions by solvent extraction with pentane, ether, and tetrahydrofuran (THF). At-125°C crosslinking of polytrifluoroethylene (PF₃E), and Kel-F 800, a co-polymer of 72% chlorotrifluoroethylene and 28% vinylidene fluoride, with phenyllithium or phenylmagnesium bromide formed glassy black insoluble products. Infrared spectroscopy showed aromatic functional groups had been introduced in all the products. However, alkyl peaks were also evident in the infrared spectra of the lithiated products. Size exclusion chromatography of soluble Kel-F 800 reaction products indicated cracking to lower molecular weight material.