Catalytic activities of binary molten salts composed of ZnCl2 and metal chlorides for hydrocracking of phenanthrene

Phenanthrene, a coal model compound, was hydrocracked in a batch autoclave at 400 °C for 3 h with an initial hydrogen pressure of 9.8 MPa and equimolar concentrations of molten salts. Binary salts composed of ZnCl₂ and metal chlorides, such as CuCl, MoCl₅CrCl₃, NiCl₂, and PdCl₂, etc., showed superior catalytic activity to pure ZnCl₂ (MCI_x/ZnCl₂ molar ratio was fixed to $\text{1}\text{4}$). The isomerization of cyclohexene and H₂?D₂ exchange reactions were also examined to estimate acid-catalytic and hydrogen-activation abilities, respectively. Both activities were found to increase with the addition of metal chloride to ZnCl₂, indicating synergistic catalytic activity. Phenanthrene conversions (as a measure of hydrocracking activities of the salts) over some catalysts correlated rectilinearly with yields of isomerized products of cyclohexane.     

Structural study of hexane-soluble products from hydroliquefaction of three Yallourn brown coal lithotypes over molten salt catalysts

The hexane-soluble fractions of hydroliquefied products from three Yallourn brown coal lithotypes have been separated into five fractions by combined silica-alumina packed column chromatography. Analyses of various fractions by g.c.-m.s. permitted the identification of ≈50 components in the saturate fraction and 40 components in the diaromatic fraction, together with 30 components in the monoaromatics. The components identified were quite similar among hexane-soluble portions of all three lithotypes. A marked predominance of even carbon number alkane (C₂₃-C₂₉) was observed in the hydrocarbon fractions from pale lithotype over $\text{ZnCl}{}_2\text{KCl}$, and medium light lithotype over both pure ZnCl₂ and $\text{ZnCl}{}_2\text{KCl}$. However, medium dark lithotype over both melt catalysts produced a saturate fraction with an odd carbon number(C₂₂-C₂₈) preference. Based on spectral methods, Soxhlet extracts obtained from untreated lithotypes (hexane and benzene solubles) were characterized as complex mixtures of higher molecular weight(300–1000) aliphatic hydrocarbons, which were supposed to be a precursor of the saturates produced from the corresponding lithotype in the catalytic hydroliquefaction.     

Effectiveness of both ZnCl2- and SnCl2-containing molten salt catalysts for hydrogenation of Big Ben coal in the absence of a solvent

Hydrogenation of Big Ben coal (Australian bituminous coal) with 9.8 MPa H₂ for 3h at 400 °C has been carried out using a batch autoclave system in the presence of a molten salt catalyst such as ZnCl₂, SnCl₂, ZnCl₂-KCl-NaCl (3:1:1 mol ratio) and SnCl₂-KCl (3:2). The hexane-soluble (HS) yield decreases in the order: SnCl₂-KCl, SnCl₂, ZnCl₂-KCl-NaCl, ZnCl₂. The use of SnCl₂-containing melt is characterized by higher yields of both HS and benzene-soluble (BS) fractions and the suppression of gas yield compared with the use of ZnCl₂. The average aromatic unit and the molecular weight of HS increase in the order: ZnCl₂, ZnCl₂-KCl-NaCl, SnCl₂, SnCl₂-KCl. Chromatographic separation of HS fractions indicates that the saturate content is lowest and polar-material content is highest with the SnCl₂-KCl melt: this fact coupled with the structural parameters suggests that HS material with SnCl₂-KCl melt has, on average, a reasonably-high-molecular-weight skeleton which has more alkyl chains and heteroatoms. Micrographs of resulting benzene-insoluble (Bl) materials clearly indicated that the Bl particles were larger when ZnCl₂ was used than when the other melts were used, the Bl particles in these cases being of similar size. Lewis acidity and the viscosity of the molten salt appear to be related, in part, to the size of the Bl particles.     

Effect of the degree of crosslinking on penetrant transport in polystyrene

The effect of the degree of crosslinking of glassy polymers on the transport mechanism of penetrants was investigated using a series of divinyl benzene (DVB)-crosslinked polystyrenes of nominal crosslinking ratio X from 0.001 38 to 0.060 mol DVB/mol styrene. The number average molecular weight between crosslinks, $\text{M}\text{?}{}_{\mathrm{<mtext>c</mtext>}}$, was determined from equilibrium swelling experiments in cyclohexane. Dynamic swelling experiments with cyclohexane at 30°C showed that the mechanism of penetrant transport was anomalous. An overshoot in the penetrant uptake was observed, characteristic of macromolecular relaxations and of changing solubility of the cyclohexane in the continuously swelling polystyrene. Photographs of various samples during the swelling process showed that solvent crazing occurred predominantly in loosely crosslinked samples.     

Polycondensation of benzyl chloride catalysed by ArCr(CO)3

Arene chromium tricarbonyls were found to function as effective homogeneous catalysts for the polycondensation of benzyl chloride when they are thermally activated. The catalytic activity and induction period depended upon the nature of the arene attached to the metal. Their activity decreased and induction time increased with respect to the nature of the arene in the order: anisole, toluene, p-xylene and benzene. The alkylation products of a model reaction, catalysed by ArCr(CO)₃, were only ortho- and para-substituted. The degree of polybenzyl branching, determined by ¹H n.m.r. and DP, was found to increase with increasing reaction temperature and $\text{M}\text{?}{}_{\mathrm{n}}$. Although there is experimental evidence that in the initiation step the arene ring remains loosely attached to the metal, a mechanism similar to that of polymerization by a Lewis acid catalyst is proposed.     

Reductive Activation of Dioxygen in Catalytic Systems Including Platinum and Heteropoly Compounds: Oxidation of Cyclohexane

Thermal activation of clayzic catalyst has been thoroughly investigated by calcining anhydrous ZnCl₂ impregnated on Mont-K10 with different ZnCl₂ loadings (0.5-2.0 mmol g^-1) under static or flowing air at 270 °C and also under N₂ flow at different temperatures (150-400 °C). Depending upon the ZnCl₂ loading and calcination temperatures, an appreciable amount of HCl is evolved in the thermal activation, indicating an occurrence of reaction between the ZnCl₂ and the surface hydroxyl groups of the clay (- OH + ZnCl₂ - O - Zn - Cl + HCl), leading to formation of new Lewis acid sites (- O - Zn -Cl). The Cl/Zn ratio, surface area and catalytic activity (in the benzene benzylation by benzyl chloride at 80 °C) of the clayzic formed in the thermal activation are influenced markedly by the ZnCl₂ loading and calcination conditions (temperature and gas atmosphere). The maximum catalytic activity for the clayzic is observed at the optimum ZnCl₂ loading (about 1.0 mmol g^-1) and calcination temperature (about 270 °C). The thermal activation at 270 °C under flowing N₂ led to a most active clayzic catalyst for the benzene benzylation. A temperature-programmed evolution of HCl in the calcination of ZnCl₂/Mont-K10 with different ZnCl₂ loadings from 25 to 400 °C at a linear heating rate of 2 °C min^-1 has also been investigated.     

Solubility increase of coal by alkylation with various alcohols

A vitrinite concentrate of Taiheyio coat has been reacted with various alcohols using ZnCl₂ as a catalyst under nitrogen pressure. The reaction conditions such as the reaction time, reaction temperature, initial nitrogen pressure and the effect of other Lewis acids as catalysts have been examined using methanol. The product from the reaction with methanol at 400 °C is fully soluble in pyridine, 57% in benzene and 26% in straight-chain hexane. This result is similar to that obtained when coal is hydrogenated under 10 MPa hydrogen pressure. Higher temperature, higher initial nitrogen pressure and longer reaction times give increased solubility. ZnCl₂ and FeCl₃ are the best catalysts. Of the various alcohols, branched alcohols give better results.     

Hydroliquefaction of Kentucky 914 coal using bottoms recycle

Kentucky $\text{9}\text{14}$ bituminous coal has been liquefied in a batch reactor using blends of distillates and SRC or SRC fractions as the solvent. The most effective solvents contained either mildly hydrogenated SRC or the cyclohexane-soluble oil fraction of SRC. Approximately 65 wt% of Kentucky $\text{9}\text{14}$ coal was converted to C₄-700K liquids using these solvents. This yield can be compared to a yield of ≈40 wt% C₄-728K produced in the SRC-II process from Kentucky $\text{9}\text{14}$ coal.     

Cloud-point curves of the polystyrene-cyclohexane system near the critical point

Cloud-point curves for solutions of five polystyrene samples, including three well-fractionated polystyrenes, in cyclohexane have been examined near their critical points. Even for a solution of polystyrene characterized by $\text{M}{}_{\mathrm{w}}\text{M}{}_{\mathrm{n}}\text{<1.03}$, the critical point determined by the phase-volume method is generally situated on the right hand branch of the cloud-point curve. The precipitation threshold concentration is appreciably lower than the critical concentration, while the threshold temperature slightly deviates from the critical temperature. The agreement of the precipitation threshold point with the critical point has been found for a solution of polystyrene characterized by M_w=20×10⁴ and $\text{M}{}_{\mathrm{w}}\text{M}{}_{\mathrm{n}}\text{<1.02}$ in cyclohexane. The η(φ) function derived from critical miscibility data is expressed by $\text{χ(φ) = 0.2798+}\text{67.50}\text{T}\text{+0.3070φ+0.2589φ}{}^2$, which yields θ of 33.2°C and ψ₁ of 0.22.     

Side-chain functionalization of polystyrene with maleic anhydride in the presence of lewis acids

Polystyrenes with different molecular weights were chemically modified with maleic anhydride by use of certain cationic catalysts of Lewis acid type (BF₃·OEt_2, AICI_3, TiCL_4, ZnCl_2, FeCl_3, and SnCl₄) in chloroform. The effects of molecular weight of polystyrene, as well as type of Lewis acid used, on properties and structure of products were investigated. The interrelation between the molecular weight of polystyrene and content of carboxyl groups in the products was made. A direct relationship between the activity of catalyst used and the number of carboxyl groups was found. For characterization of side-chain functionalized polystyrene, fractional precipitation was applied which yielded carboxyl groups in all fractions. The carboxyl group concentrations were found to be the highest in the case of BF₃·OEt_2. Modified polystyrene samples containing  CO CHCH COOH fragments in side chains are easily crosslinked at 140–150°C and by UV irradiation as proved by IR, DTA, and TGA analyses. Functionalized polymers obtained are characterized by their high thermostability, adhesion, and photosensitivity. © 1996 John Wiley & Sons, Inc.     

Synthesis and solution properties of comb polystyrenes

A new method for the synthesis of comb shaped polystyrenes of predetermined structure is described. Silicon-chlorine bonds are introduced into the backbone polystyrene by reaction of SiMe₂Cl₂ with hydrolysed styrene/vinyl acetate copolymers and coupled with polystyryl-lithium in benzene. From a common backbone polymer a series of comb polymers are prepared that have a constant number of branches but vary in branch length. The $\text{M}{}_{\mathrm{w}}\text{M}{}_{\mathrm{n}}$ of the whole comb polymers is about 1.3. The comb polymers with high branch density show θ (A₂) temperatures lower than that for linear polystyrene. The radius of gyration at θ (A₂) [〈S²〉_{θ (A2)}] is always larger than calculated from random flight statistics. For comb polymers with 20–30 branches increases with λ^?0.46 where λ is the fraction of polymer in the backbone. The intrinsic viscosities of the comb polystyrenes at θ (A₂) are equal to that of the parent backbone polymer when λ > 0.25 and increase only little when λ becomes equal to 0.1. Similar behaviour is found in toluene. Intrinsic viscosities in cyclohexane at 35°C show a complex pattern because of the θ-temperature variation.     

Determination of intrinsic viscosity of fractionated pitches and discussion on the shape and size of pitch molecules

Intrinsic viscosity η of fractionated petroleum pitches in benzene solution was measured by using a capillary viscometer of Ubbelohde type. Molecular weight fractionation of the pitch was successfully carried out by using non-polar solvents, benzene and n-hexane. The dependence of η on molecular weight ?M_n is found to be as ?M_n^{$\text{1}\text{10}$}, from which the shape of the pitch molecules is concluded to be three-dimensional, rather than planar. Some discussion of the hydrodynamically equivalent size and of the configuration of the pitch molecules is given.     

Definition of fossil fuel-derived asphaltenes in terms of average structural properties

Molecular mass and polarity alone do not adequately explain the benzene solubility of all fossil fuel-derived asphaltenes. To account for the solubilities of a wide selection of asphaltenes in terms of average structural properties, it has been necessary to consider also the nature of the aromatic structures by deducing the proportion of internal (bridgehead) aromatic carbon to total carbon ($\text{C}{}_{\mathrm{INT}}\text{C}$). This takes account of both the amount and degree of condensation of aromatic nuclei. Three-dimensional plots of number average molecular mass, the % acidic OH (measure of polarity) and $\text{C}{}_{\mathrm{INT}}\text{C}$ give boundaries between benzene insolubles, asphaltenes and n-pentane solubles. An empirical solubility parameter has been defined which gives values for asphaltenes in the range 0.85-1.2, compared with ? 0.6 for n-pentane solubles and ? 1.25 for benzene insolubles.     

Conversion of bituminous coal in COH2O systems: 2. pH Dependence

Under $\text{CO}\text{H}{}_2\text{O}$ systems at initial pH values s> 12.6, an Illinois No. 6 coal, PSOC-26, was converted to a fully pyridine-soluble product, with benzene and hexane solubilities of 50% and 18%, respectively. The product gases were H₂ and CO₂. However, the expected $\text{H}{}_2\text{CO}{}_2$ ratio of 1.0 based on the water gas shift reaction was not observed, but the deficit in hydrogen was found in the increased hydrogen content of the coal product. 95% coal carbon recovery and good hydrogen balances were obtained, and the coal products were found to be very similar to those from conventional tetralin systems. The results suggest an efficient base-catalysed process, and that $\text{CO}\text{H}{}_2\text{O}$ systems are useful for coal studies.     

Properties of extremely high molecular weight polystyrene in solution

Extremely high molecular weight polystyrenes with a $\text{M}\text{?}{}_{\mathrm{w}}$ in the range 10.8 × 10⁶ to 2.2 × 10⁷ were prepared by emulsion polymerization initiated with a heterogeneous initiator at 30°C, which has a ‘living character’. Samples of polystyrene were characterized by light scattering and viscometry in toluene and benzene at 25°C, and in θ-solvent cyclohexane at 34.8°C. Also determined were the relationships of mean-square radius of gyration 〈s²〉 (m²) and the second virial coefficient A₂ (m³ mol kg^?2) on the molecular weight, which for toluene and benzene are described in equations: Toluene (25°C) $\text{〈s}{}^2\text{〉=1.59 × 10}{}^{\mathrm{?23}}\text{M}\text{?}{}_{\mathrm{w}}{}^{1.23}$; $\text{A}{}_2\text{=4.79 × 10}{}^{\mathrm{?3}}\text{M}\text{?}{}_{\mathrm{w}}{}^{\mathrm{?0.63}}$; Benzene (25°C) $\text{〈s}{}^2\text{〉=1.23 × 10}{}^{\mathrm{?22}}\text{M}\text{?}{}_{\mathrm{w}}{}^{1.20}$; $\text{A}{}_2\text{=2.59 × 10}{}^{\mathrm{?3}}\text{M}\text{?}{}_{\mathrm{w}}{}^{\mathrm{?0.59}}$. The parameters in the Mark-Houwink-Sakurada equation were established, for extremely high molecular weight polystyrene in toluene and in benzene, at 25°C into the form giving for $\text{[η] (}\text{m}{}^3\text{kg}{}^{\mathrm{?1}}\text{): [η] = 8.52 × 10}{}^{\mathrm{?5}}\text{M}\text{?}{}_{\mathrm{w}}{}^{0.61}$; $\text{[η] = 1.47 × 10}{}^{\mathrm{?4}}\text{M}\text{?}{}_{\mathrm{w}}{}^{0.56}$. The mentioned relations, as well as the obtained values of Flory parameter ?₀ and of ratio $\text{[η]}\text{M}\text{?}{}_{\mathrm{w}}{}^{0.5}$ were compared with solution properties of high molecular weight polystyrene with narrow molecular weight distribution prepared by anionic polymerization by Fukuda et al.     

Viscometric behaviour of polystyrene in tetralin/cyclohexane mixtures

For solutions of polystyrene (M=10⁵–10⁶ g mol^?1), intrinsic viscosities [η] have been measured at 34.5°C, which is the θ temperature for the polymer in cyclohexane. The solvents comprised cyclohexane in admixture with a thermodynamically good solvent, 1,2,3,4-tetrahydronaphthalene (tetralin, TET) over the whole range of solvent composition. From an assessment of several extrapolation procedures, a value of 85 × 10^?3$\text{(±1 × 10}{}^{\mathrm{?3}}\text{)}\text{cm}{}^3\text{g}{}^{\mathrm{<mtext>?3</mtext><mtext>2</mtext>}}\text{mol}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was obtained for K_θ (in the relationship $\text{[η] = K}{}_{\mathrm{\theta }}\text{M}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{α}{}^3$, where α is the expansion factor), thus yielding $\text{0.681}\text{A}\text{?}\text{g}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}\text{mol}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, 2.25 and 10.2 for the unperturbed dimensions, steric factor σ and characteristic ratio C_∞ respectively. The value of K_θ was independent of solvent composition despite the finite excess free energy of mixing for the solvent components alone, which has been asserted elsewhere to affect K_θ. The present results, in conjunction with previous ones relating to 98.4°C, indicate a value of ?0.89 × 10^?3 deg^?1 for the temperature coefficient of the unperturbed dimensions.     

Effects of Lewis acid catalysts on the hydrogenation and cracking of three-ring aromatic and hydroaromatic structures related to coal

Little is known about the hydrogenation and cracking of fused aromatic nuclei during the liquefaction of coal under the influence of Lewis acid catalysts. This study was conducted to establish the effects of catalyst acidity on the activity and selectivity of Lewis acid catalysts, the sources of hydrogen involved in hydrogenation and cracking, and the relationships between reactant structure and reactivity. Three-ring aromatic and hydroaromatic compounds were used to simulate some of the structural units present in coal. The catalysts examined were ZnCl₂ and AlCl₃. It has been established that the rates of both processes are strongly influenced by the Brönsted acidity of the active catalyst, e.g. H⁺ (MX_nY)^?, and the Brönsted basicity of the aromatic portions of the reactant. The source of the hydrogen used for hydrogenation depends on the choice of catalyst. In the presence of AlCl₃, Scholl condensation of aromatic nuclei serves as the principal source of hydrogen. Molecular hydrogen is used exclusively, however, when hydrogenation is catalysed by ZnCl₂. The formation of reaction products and the trends in reactant reactivity are discussed on the basis of cationic mechanisms. The results of this study contribute to an understanding of the processes which occur during the liquefaction of coal using ZnCl₂ or AlCl₃.     

Investigation of the structure of poly(p-chlorophenyl glycidyl ether) by the 13C n.m.r. technique: tacticity and addition isomerism

The p-chlorophenyl glycidyl ether was polymerized in the presence of Al(OiPr)₃, ZnCl₂, SnCl₄, BuOK, KOH and by the Al(OiPr)₃ZnCl₂ 1:1 initiator system. Analysis of the ¹³C n.m.r. spectra of the poly(p-chlorophenyl glycidyl ethers) obtained has made it possible to determine their tacticity and the content of the head-to-tail and head-to-head linkages in the polymer chain.     

Effect of ZnCl2‐ and SiCl4‐doped TiCl4/MgCl2/THF catalysts for ethylene polymerization

In this research, ethylene polymerization was carried out in the presence of different additives (ZnCl₂, SiCl₄, and the combined ZnCl₂‐SiCl₄) on TiCl₄/MgCl₂/THF catalytic system. The presence of ZnCl₂‐SiCl₄ mixtures showed higher activity in ethylene polymerization when compared with the catalytic activity in the presence of single Lewis acids, ZnCl₂, or SiCl₄. The modified catalyst with ZnCl₂‐SiCl₄ demonstrated the highest activity, which was more than three times the activity of the system without Lewis acid modification. The enhanced activity can be attributed to the reduction in the peak intensity of MgCl₂/THF complexes with Lewis acid compounds as proven by XRD. This was reasonable because of some THF removal from the structure of MgCl₂/THF by Lewis acid compounds. In addition to the effect of modification with additives on the partial elimination of THF, the catalytic activities could be increased due to the titanium atoms that have been locally concentrated on the surface as seen by energy dispersive X‐ray spectroscopy measurement. On the basis of the in situ electron spin resonance measurement, the mixed metal chlorides (ZnCl₂‐SiCl₄) addition could promote the amount of Ti³⁺after reduction with triethylaluminum. It revealed that the modification of TiCl₄/MgCl₂/THF catalytic system with mixed metal chlorides (ZnCl₂‐SiCl₄) is very useful for ethylene polymerization. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1588–1594, 2013