Hydrogenation and Ring Opening of Aromatic and Naphthenic Hydrocarbons Over Noble Metal (Ir,Pt, Rh)/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts

Abstract  

The hydrogenation and ring opening of model hydrocarbons and of naphtha was studied over commercial noble metal (Ir, Pt, Rh)/Al₂O₃ catalysts. The experiments were performed in a fixed bed reactor at temperatures between 220 and 350 °C and pressures of 1.1 and 5.0 MPa, respectively. The product distribution was determined and the cetane number was calculated. The Pt catalyst is very active for hydrogenation of aromatics but does not catalyse the ring opening of naphthenes. The Ir and Rh catalysts are active for both hydrogenation of aromatics and ring opening of naphthenes. Experiments with toluene, m-xylene, propyl-benzene, and methylcyclohexane indicate that ring opening follows a selective mechanism, where the cleavage of bisecondary carbon bonds is favoured. This results in predominant formation of branched paraffins. The product distribution as well as cracking of long-chain hydrocarbons, which increase at temperatures above 260 °C, lead to an insignificant boost in the cetane number, as confirmed by experiments using real naphtha as feedstock.     

Aufklärung der Molekülstruktur von Rohölinhaltsstoffen durch NMR-Spektroskopie. IV. Strukturtypen- und Strukturgruppenanalyse von Erdölfraktionen durch 1H-NMR-Spektroskopie

Elucidation of the Molecular Structure of Petroleum Constituents by N.M.R. Spectroscopy. IV. Analysis of Petroleum Fractions with Respect to Types of Structure and Structural Groups by ¹H N.M.R. Spectroscopy An improved method is presented which permits a quantitative analysis of crude oil products with a final boiling point below 400°C by means of the data of the ¹H n.m.r. spectrum and the average boiling point of the petroleum fractions. The types of aromatic structures are distinguished with respect to mono-, bi-, and tricyclic aromatics, and additionally, further structural group information is obtained.     

Influence of metal‐oxide‐supported bentonites on the pyrolysis behavior of polypropylene and high‐density polyethylene

In this article, we report on the pyrolysis of polypropylene (PP) and high‐density polyethylene (HDPE) in the absence and presence of plain and metal‐oxide‐impregnated bentonite clays [BCs; acid‐washed bentonite clay (AWBC), Zn/AWBC, Ni/AWBC, Co/AWBC, Fe/AWBC, and Mn/AWBC] into useful products. Thermal and catalytic runs were performed at 300°C in the case of PP and at 350°C in the case of HDPE for a contact time of 30 min. The effects of different catalysts and their concentrations on the overall yields and the yields of liquid, gas, and residue were studied. The efficacy of each catalyst is reported on the basis of the highest liquid yields (in weight percentage). The derived liquid products were analyzed by Fourier transform infrared spectroscopy and gas chromatography–mass spectroscopy; this confirmed the presence of paraffins, olefins, and naphthenes. The results indicate the catalytic role of impregnated BCs compared to plain BC with the optimum efficiency shown by Co/AWBC in the case of PP and Zn/AWBC in the case of HDPE toward the formation of liquid products in a desirable C range with the enrichment of olefins and naphthenes in the case of PP and paraffins and olefins in the case of HDPE compared to the thermal run. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41221.     

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.     

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     

Polyamides obtained by direct polycondesation of 4‐[4‐[9‐[4‐(4‐aminophenoxy)‐3‐methyl‐phenyl] fluoren‐9‐YL]‐2‐methyl‐phenoxy]aniline with dicarboxylic acids based on a diphenyl‐silane moiety

Polyamides (PAs) containing fluorene, oxyether, and diphenyl‐silane moieties in the repeating unit were synthesized in > 85% yield by direct polycondesation between a diamine and four dicarboxylic acids. Alternatively, one PA was synthesized from an acid dichloride. The diamine 4‐[4‐[9‐[4‐(4‐aminophenoxy)‐3‐methyl‐phenyl]fluoren‐9‐yl]‐2‐methyl‐phenoxy]aniline ( 3 ) was obtained from the corresponding dinitro compound, which was synthesized by nucleophilic aromatic halogen displacement from p‐chloronitrobenzene and 9,9‐bis (4‐hydroxy‐3‐methyl‐phenyl)fluorene ( 1 ). Monomers and polymers were characterized by FTIR and ¹H, ¹³C, and ²⁹Si‐NMR spectroscopy and the results were in agreement with the proposed structures. PAs showed inherent viscosity values between 0.14 and 0.43 dL/g, indicative of low molecular weight species, probably of oligomeric nature. The glass transition temperature (T_g) values were observed in the 188–211°C range by DSC analysis. Thermal decomposition temperature (TDT_10%) values were above 400°C due to the presence of the aromatic rings in the diamine. All PAs showed good transparency in the visible region (>88% at 400 nm) due to the incorporation of the fluorene moiety. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Aufklärung der Molekülstruktur von Rohölinhaltstoffen durch NMR-Spektroskopie. I. Struktur der Isoparaffine des Rohöls

Elucidation of the Molecular Structure of Petroleum Constituents by NMR Spectroscopy. I. Structure of Branched Paraffins in Petroleum Crude A correlation between the ¹³C resonance peaks and possible structural elements of branched paraffins of petroleum fractions is given. New information concerning the structure of branched paraffins of petroleum crude is provided.     

Untersuchung zur Ringöffnungspolymerisation von 2-Phenoxymethyl-1,4,6-trioxa-spiro-[4,4]-nonan

Investigation of Ring-Opening Polymerization of 2-Phenoxymethyl-1,4,6-trioxa-spiro[4,4]-nonan Under the conditions of a radical induced cationic ringopening-polymerization the spiro ortho ester 1b can be polymerized with diphenyliodoniumtetrafluorborat/benzpinacol (1:1). The optimal initiator concentration is 2–2.5 mol-% Ph₂I⁺BF₄⁻. The average molecular weight is 6000, Tg = −4°C. Polymerization of 1b in presence of BF₃ · Et₂O produced identical results. The structure of polymer 2b was indicated by its analysis as well as its infrared spectra.     

Catalytic dehydrochlorination of the solid poly(vinyl chloride) in the presence of aluminium chloride (friedel-crafts) catalyst: Studies of the structure by spectroscopical methods

Catalytic dehydrochlorination (100%) of solid poly(vinyl chloride) (PVC) in the presence of AlCl₃ at 200°C gives a product which has a similar structure to the product of catalytic dehydrochlorination of 1,2-dichloroethane in the presence of AlCl₃ at 60°C. Both products have brown-black color, are completely insoluble, thermally resistant up to more than 400°C, and exhibit conductivities in the range 10^?6 S cm^?1 (after doping with FeCl₃ or I₂ conductivities: 10^?5 S cm^?1). Different spectroscopical methods such as UV/VIS, IR, Raman, ESCA, and ¹³C-NMR were employed to the structure study of both products, which are crosslinked polyenes with a number of aromatic rings.     

Selektive Härtung von Fetten und Fettsäuren mit Sulfiden der Übergangsmetalle als Katalysatoren

Selective Hydrogenation of Fats and Fatty Acids with Sulfides of Transition Metals as Catalysts Sulfides of some transition metals are suitable as catalysts for the selective hydrogenation of fats and fatty acids. Ni₃S₂, a stoichiometrically, thermally and crystallographically defined compound is especially active. Also mixed catalysts containing tungsten sulfide and molybdenum sulfide besides Ni₃S₂ are sufficiently active. The same is true for cobalt sulfide catalysts, whereas molybdenum sulfide and tungsten sulfide exhibit considerably lower activities. The conditions of hydrogenation are essentially the same as customary: temperature range 180° to 210°C for fats, 200° to 220°C for fatty acids, hydrogen pressure 2–25 kg/cm², catalyst concentration 0.05 to 2 parts by weight of metal sulfide per 100 parts of fat or 0.5–5 parts by weight of metal sulfide per 100 parts of fatty acids. Using the above catalysts, the selectivity of S₃₁ or S₂₁ attained in the steps triene (polyene → monoene or diene → monoene is over 75. The remaining double bonds in the hydrogenated product possess almost exclusively the trans configuration. The above catalysts are resistant to sulfur compounds and they exhibit exceptional longevity. The regeneration can be performed with ease. Consequently, the pretreatment of the material to be hydrogenated can be limited to washing and drying.     

Herstellung und Eigenschaften von niedermolekularen epoxydierten aromatischen Polyäthern

The synthesis of low molecular weight epoxidated aromatic polyethers from oligomers with phenolates of alkali metals as terminal groups with epichlorohydrin in anhydrous aprotonic, polar solvents is presented. The oligomers having ? ONa or ? OK terminal groups have been synthesized by condensation of alkali metal salts of bisphenols with chlorobisphenyl compounds containing bivalent electronacceptor groups between the aromatic rings. The molar ratio of chlorobisphenyl compounds to bisphenol was in the range of 0,5:1 to 0,9:1. The dependence of reactivity of the above mentioned epoxidated oligomers in the curing reaction with diaminodiphenylsulfone (DDS) on the molecular weight and type of bisphenol has been investigated. Thermal and thermomechanical properties of these resins have been determined. The degradation temperature of the uncured resin (mw 800) obtained on the base of polysulfone oligomer was 325°C (1,5 wt.-% weight loss). The resin cured by means of DDS had a glass transition temperature of 160°C, and a tensile strength of 160–190 kg/cm², measured as adhesive between aluminium plates.     

Polymerization of acrylated epoxidized soybean oil with phenol furfural resins via repeated forward and retro diels–alder reactions

In this work, the Diels–Alder reaction between the acrylate groups of acrylated epoxidized soybean oil and the furan rings of p‐tertiary butyl phenol furfural resin (TBPF) is described. The reaction was carried out at 110°C in presence of FeCl₃ catalyst, and tough polymers were obtained in 1 h. Surprisingly, samples that were heated and cooled 5, 10, and 20 times to 140°C and room temperature had better mechanical properties than samples that were kept at 140°C for the same total duration. This unexpected behavior is attributed to a series of forward and retro Diels–Alder reactions between the functional groups. To prove this hypothesis, a model reaction between TBPF and n‐butyl acrylate was studied. At 100°C, ¹H‐nuclear magnetic resonance signals of the furan ring protons disappeared, only to reappear at 140°C. Thermogravimetric analysis of the adduct showed a weight loss at 140–150°C, which was in quantitative agreement with the amount of butyl acrylate. Infrared analysis showed that furan rings were not completely consumed by extended heating at 110°C. After five heating and cooling cycles of much shorter duration at 140°C, the furan absorption in the infrared disappeared. The storage modulus of acrylated epoxidized soybean oil‐TBPF samples after 20 heating cycles was 1.15 GPa. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polymerisation von Vinylchlorid bei Atmosphärendruck 1. Polymerisationssysteme zur Herstellung von U-PVC

A method for polymerization of vinylchloride (VC) at atmospheric pressure is described, in which the gaseous monomer is polymerized with K₂S₂O₈ as an initiator at 45°C to 60°C. The amount of the polymer formed (so-called U-PVC) as a function of the reaction time depends on the rate of monomer flow. The reaction rate increases with higher initiator concentration as well as with increasing temperature. It is also possible to initiate the polymerization with the redox-system K₂S₂O₈/Na₂SO₃/Cu²⁺ within the range of 0°C to 20°C. By means of transmission electronmicroscopic (TEM) investigations the particle size and particle size distribution as a function of polymerization time and temperature was determined.     

Synthesis and characterization of some aromatic polyimides

The diamine 2‐methyl‐1,3‐bis(4‐aminophenyloxy)benzene was prepared via a nucleophilic substitution reaction and was characterized with Fourier transform infrared, elemental analysis, and ¹H‐ and ¹³C‐NMR spectroscopy. The prepared diamine was also characterized with single‐crystal analysis. The geometric parameters of C₁₉H₁₈N₂O₂ were in the usual ranges. The dihedral angles between the central phenyl ring and the two terminal aromatic rings were 88.9 and 91.6°. The crystal structure was stabilized by N? H···N hydrogen bonds. The diamine was then polymerized with 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 3,4,9,10‐perylenetetracarboxylic acid dianhydride, and pyromellitic dianhydride by either a one‐step solution polymerization reaction or a two‐step procedure. These polymers had inherent viscosities ranging from 0.61 to 0.85 dL/gm. Some of the polymers were soluble in most common organic solvents even at room temperature, and some were soluble on heating. The degradation temperatures of the resultant polymers fell in the range of 260–500°C in nitrogen (with only 10% weight loss). The specific heat capacity at 200°C ranged from 1.0 to 2.21 J g^?1 K^?1. The temperatures at which the maximum degradation of the polymer occurred ranged from 510 to 610°C. The glass‐transition temperatures of the polyimides ranged from 182 to 191°C. The activation energy and enthalpy of the polyimides ranged from 44.44 to 73.91 kJ/mol and from 42.58 to 72.08 kJ/mol K, respectively. The moisture absorption was found in the range of 0.23–0.71%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Intrinsic viscosity–molecular weight relationship for low molecular weight nylon 6

Samples of nylon 6 have been prepared by the hexamethylene diamine-initiated polymerization of ?-caprolactam at 220°C. Fractionation of these with m-cresol–diethyl ether at 26°C yielded 15 amino-terminated fractions of M?_n of 337–10,940 determined conductometrically. Below M?_n = 4,306 the Mark-Houwink parameters in m-cresol at 30°C are K = 3.0 × 10^?3 dl/g and v = 0.53 ± 0.02. Thereafter v exhibits a pronounced increase. The value of K is similar to the values of Kθ derived from Stockmayer-Fixman plots of published data in good solvents. The findings thus corroborate a current hypothesis that fractionated, low molecular weight polymers in good solvents tend to behave viscometrically, as if they were under θ conditions (i.e., K = K_θ and v = 0.50).     

Preparation,characterization, and retarding mechanism of high temperature resistant amphoteric ion polymer oil well cement retarder Poly-AAMD for HTHP application

The amphoteric ion polymer cement retarder Poly-AAMD was synthesized by aqueous solution polymerization, the chemical structure, molecular weight, and thermal stability was studied. As a result, the M_n and M_w are 1.3 × 10⁴ and 4.7 × 10⁴ g/mol, respectively, and the initial decomposition temperature is 260°C. Then, the effects of retarder Poly-AAMD on the application performance of cement slurry, such as settlement stability, thickening time, compressive strength, and rheological properties, were investigated. Especially, the thickening time of cement slurry with 1.2 and 1.5 wt% retarder Poly-AAMD is 312 and 316 min at 220°C, the compressive strength is larger than 14 MPa at 24 h. Compared to conventional retarders, the temperature resistance has been improved to 220°C. Simultaneously, the initial hydration process of cement slurry was studied by low field NMR based on the T₂ value. Moreover, the hydration products of cement slurry with retarder Poly-AAMD were analyzed depends on the qualitative and quantitative analysis methods, the type and content of hydration products were confirmed by the methods of X-ray diffraction analysis (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TG), and differential thermal analysis (DTG). Finally, the retarding mechanism of retarder Poly-AAMD was further studied depends on the results of adsorption amount and Zeta potential.     

Synthesis of soluble and thermally stable polyamides from diamine containing (quinolin‐8‐yloxy) aniline pendant group

A novel diamine monomer having pendant 4‐(quinolin‐8‐yloxy) aniline group was successfully synthesized via aromatic substitution reaction of 8‐quinolinol with p‐fluoronitrobenzene followed by Pd/C catalyzed hydrazine reduction, amidation reaction between 4‐(quinolin‐8‐yloxy) aniline and 3,5‐dinitrobenzoylcholoride followed by Pd/C catalyzed hydrazine reduction. The diamine monomer was fully characterized by using FTIR, ¹H‐NMR, ¹³C‐NMR, and elemental analysis. The diamine monomer was polymerized with various aromatic and aliphatic dicarboxylic acids to obtain the corresponding polyamides. The polyamides had inherent viscosity in the range of 0.30–0.41 dL/g and exhibited excellent solubility in the polar aprotic solvents such as DMAc, NMP, N,N‐dimethylformamide, Pyridine, and DMSO. The glass transition temperatures (T_g) of the polymers are high (up to 313°C) and the decomposition temperatures (T_i) range between 200 and 370°C, depending on the diacids residue in the polymers backbone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Chlorination of Pt–Re/Al2O3 during naphtha reforming

The reforming of a paraffinic naphtha was studied in order to determine the influence of chlorination during the run. Experiments were performed at 505°C, 15 kg cm⁻², WHSV = 4, H₂: HC= 4, and with or without an 8 h initial period of deactivation at 1 kg cm⁻². A commercial Pt–Re/Al₂O₃ (0·3% Pt, 0·3% Re, 0·04% S, 0·15% Cl) catalyst was chlorinated using naphtha feeds with different H₂O/Cl ratios. A model of the chlorination kinetics was developed and represents adequately the experimental results. The acid controlled reactions such as C₂–C₄ and production of C₅ paraffins, disappearance of C₉ paraffins and production of aromatics increase in parallel to the chlorination of the catalyst and the increase is independent of the amount of coke deposited on the catalyst. The sites of chlorine adsorption are different from the sites of coke deposition.     

Synthesis and characterization of aromatic/cycloaliphatic poly(amide‐ imide‐imide)s from bis(4‐amino‐ 3,5‐dimethylphenyl) cycloalkane derivatives

A series of novel aromatic diamines containing cycloaliphatic moieties was synthesized by the reaction of cycloalkanones like cyclohexanone and cycloheptanone with 2,6‐dimethylaniline. The tetrimide diacid was synthesized using the prepared diamine with 3,3′,4,4′‐benzophenonetetracarboxylic acid dianhydride/pyromellitic dianhydride and p‐aminobenzoic acid. The polymers were prepared by treating the tetrimide diacid with different aromatic diamines. The structures of the monomers and polymers were identified using elemental analysis and Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopy. The polymers show excellent solubility. The polymers are amorphous and have high optical transparency. They also show good thermal stability and their T_g value is found to be in the range 268–305 °C. Copyright © 2007 Society of Chemical Industry     

Phosphonitrilic chloride. XXVI. Synthesis of cyclophosphazene polymer by polycondensation reaction of tetrachlorodiphenyl triphosphazene and aromatic diamine compounds

Tetrachlorodiphenyl cyclotriphosphazene N₃P₃Cl₄(C₆H₅)₂ (TPC) has been synthesized by Friedel-Crafts reaction. The polycondensation of TPC with aromatic diamine compounds has been carried out in pyridine. The products obtained from the reaction of TPC with aromatic diamine compounds were slightly soluble in polar organic solvents. The molecular weights measured by the method of end group analysis were about 2800 to 10800. The products were amorphous, brown, yellow or white coloured solids. The softening points of all polycondensation products were found to be in the region of 100°C to 120°C. The electrical conductivity of the products obtained from TPC with p-phenylenediamine and p,p′-diaminodiphenyl sulfone was determined to 5 × 10¹² (Ωcm)^?1 and 1 × 10¹⁵ (Ωcm)^?1, respectively.