Showing papers in "Petroleum Chemistry in 2009"

Binder-free syntheses of high-performance zeolites A and X from kaolin

Abstract: The crystallization behavior of metakaolin (Al2Si2O7) at 25–100°C in solutions of sodium hydroxide and sodium silicate with different concentrations was studied, and the conditions for its conversion into finely divided, high-crystallinity zeolites of types A and X were determined. On the basis of the product zeolites and kaolin, procedures were developed for the preparation of pelleted, binder-free materials as polycrystalline accretions of zeolites A and X, which do not rank below pelleted zeolites obtained from synthetic feedstock.

Petroleum acids and corrosion

Abstract: The current state of research in petroleum acid corrosion of metals is surveyed. It is shown that the corrosion of refinery equipment caused by petroleum naphthenic acids is a multifactor process. The general characteristics of the acid content in crude oils and the acid number give quite a rough evaluation of the corrosive power of oils, and the determining factors useful for evaluation are the type, structure, and functionality of petroleum acids. Effective ways of preventing petroleum acid corrosion of metals are comprised of the demineralization and careful alkali treatment of crude oil, the use of organic corrosion inhibitors, and improvement in the metal quality by alloying with anticorrosive additives. Methods for simulation of the metal corrosion processes caused by petroleum acids are becoming of substantial importance.

Conversion of dimethyl ether into C2-C4 olefins on zeolite catalysts

Abstract: The effect of the nature of the metal introduced into HZSM-5 on the properties of the catalysts for the synthesis of olefins from dimethyl ether was studied. By means of the ammonia temperature-programmed desorption technique, it was shown that a decrease in the total amount of acid sites increases the selectivity for lower olefins. As the ratio of the medium to strong acid sites increases, the yield of olefins increases. The effect of the nature of gaseous additives in the feedstock on the selectivity for lower olefins was studied at T = 340°C, p = 0.1 MPa, and ν0 = 2000 h−1.

Effect of various sono-oxidation parameters on the desulfurization of diesel oil

Abstract: The influences of ultrasonic intensity, H2O2 concentration, ratio of H2O2 to oil and the addition of Fenton reagent on the oxidative desulfurization of diesel oil under ultrasonic irradiation were investigated. It was observed that the oxidative desulfurization of diesel oil fitted pseudo-first-order kinetics under our experimental conditions. Increasing the ultrasonic intensity increased the oxidative desulfurization efficiency of diesel oil. The addition of H2O2 enhanced the ultrasonic oxidative desulfurization efficiency of diesel oil. The sono-oxidation treatment in combination with Fenton reagent showed a synergistic effect for diesel oil desulfurization. The catalytic oxidative desulfurization process under ultrasonic irradiation process on diesel oils is an efficient and promising method.

Isomerization of n-hexane over bifunctional Pt/SO4/ZrO2 catalysts

Abstract: The catalytic properties of model Pt/SiO2 and Pt/Al2O3 catalysts and their physical mixtures with SO4/ZrO2 in the reaction of n-hexane isomerization have been studied. Significant effects of the influence of the platinum state on the characteristics of isomerization on the catalysts and their physical mixtures with SO4/ZrO2 have been revealed. The observed changes in catalytic performance of the mixed catalysts have been explained from the position of a bifunctional mechanism with the participation of ionic platinum promoting the formation of hydride ions, which play an important role in the activation of transformations of intermediates in isomerization reactions.

New model calculates solubility of light Alkanes in triethylene gycol

Abstract: New model, which cover the full range of dehydration-plant operating conditions and wide range of experimental data results, estimate the amount of CH4, C2H6 and C3H8 absorbed per volume of triethylene glycol (TEG) circulated vs. the reduced partial pressure of light Alkanes and the absorber reduced temperature. TEG has a tendency to remove the hydrocarbons. Hydrocarbon solubility is a major factor when considering the use of a physical solvent. Quantifying this amount of absorption is critical in order to minimize hydrocarbon losses or to optimize hydrocarbon recovery. This article provides comparisons with experimental data.

Catalytic hydrogenation of dicyclopentadiene to dicyclopentene in the liquid phase

Abstract: A new use for dicyclopentadiene has been proposed in the area of preparation of oxygen-containing compounds, including those with a cage structure, the key stage of which is the selective liquid-phase hydrogenation of dicyclopentadiene to dicyclopentene with hydrogen over finely divided hydrogenation catalysts based on platinum group metals. The process proceeds under mild conditions at atmospheric pressure. Conditions providing a yield of 92% for the desired product with an almost complete conversion of the reactant dicyclopentadiene have been determined in the study of the hydrogenation reaction in both a volumetric device of the closed type and a continuous-flow system.

New routes for the manufacturing of isoparaffins as environmentally friendly, high-octane components of motor gasoline

Abstract: Toughening the quality standards for petroleum fuels suggests a substantial reduction in the amount of aromatic hydrocarbons in these fuels; in particular, the benzene content should not exceed 1.0%. Securing these requirements by legislation forces oil refiners to revise the hydrocarbon-group composition of motor gasolines and, hence, the engineering basis of their manufacture. The main world tendency for the hydrocarbongroup composition of motor gasoline is to increase the proportion of isoparaffins from 20 to 45%, which is equivalent to a reduction in the amount of aromatic hydrocarbons from 42 to 25%. The designing of a new industrial process for isobutane alkylation with olefins and the discovery of the new reaction of reductive dehydration of alcohols yielding isoparaffinic and, in particular, alkylcyclopentane hydrocarbons contribute to the production of alternative, environmentally safe motor fuels.

Biomarkers in the pyrolysis products of asphaltenes from ancient crude oils of East Siberia as indicators of source rock depositional environment

Abstract: The hydrocarbon composition of the pyrolysis products of asphaltenes isolated from ancient crude oils of East Siberia was determined by the gas chromatography-mass spectrometry technique and was compared with that for Oman oils. The study resulted in the conclusion that the source rocks of both East Siberia and Oman had been deposited under identical facial conditions with similar compositions of source biota.

The Role of N-hydroxyphthalimide in the oxidation reactions of alkylarenes with molecular oxygen

Abstract: The kinetics of the liquid-phase oxidation of alkylarenes with molecular oxygen in the presence of the initiators azobisisobutyronitrile and benzoyl peroxide and the catalyst N-hydroxyphthalimide (NHPI) was studied. It was found that the rate of oxidation of alkylarenes depended on the partial pressure of oxygen, an effect that is explained by its involvement in the reaction with NHPI resulting in the initiation of the oxidation chain.

Kinetic Parameters and Geometry of the Transition State in the Unimolecular Degradation of Alcohols

Abstract: Experimental data on the unimolecular degradation of structurally different alcohols, alkanols into water and an olefin and alkenols into a carbonyl compound and an olefin, were analyzed in terms of the method of crossing parabolas. The kinetic parameters characterizing such decomposition were calculated and factors that affect the activation energy of the reaction (the cycle strain energy, the steric factor, and the effect of π electrons neighboring the reaction center) were determined. The activation energies and the rate constants were calculated for 30 alcohol degradation reactions. The enthalpies, the activation energies, and the rate constants of degradation of unsaturated alcohols were compared for two different degradation routes yielding a carbonyl compound and an olefin or resulting in water and an olefin. Quantum-chemical calculations of the transition states for three model reactions were performed. The activation energies and the rate constants were obtained for the first time for 13 reverse reactions of the addition of carbonyl compounds to olefins.

Liquid-phase oxidation of benzene and phenol on MCM-41 mesoporous molecular sieves modified with iron and cobalt compounds

Abstract: Nanostructured (I) Fe2O3 and Co3O4 stabilized in the mesopores of an MCM-41 sieve and immobilized (II) FeCl2, Fe(acac)3, and FePc on the surface of an MCM-41 sieve functionalized with 3-aminopropyltriethoxysilane (3-APTES) were synthesized and examined. The materials were characterized by elemental analysis, H2 -TPR, X-ray diffraction analysis, IR and electronic absorption spectroscopy, as well as by low-temperature N2 adsorption. The catalytic activity was evaluated in the reaction of liquid-phase oxidation of benzene and phenol with hydrogen peroxide. Catalysts I showed a low activity in benzene oxidation, whereas catalysts II were active in the oxidation of phenol.

Two alternative mechanisms of aromatization of light hydrocarbons on Ga/ZSM-5 and Zn/ZSM-5 zeolites

Abstract: By means of IR diffuse reflectance spectroscopy, it was shown that aromatization of light paraffins on the GaZSM-5 and ZnZSM-5 catalysts occurs through different routes. The first step of transformation on GaZSM-5 is the oxidative addition of paraffin molecules to Ga+ ions resulting in homolytic dissociation and the appearance of particles [H-Ga-R]+, whereas dehydrogenation on zinc-containing high-silica zeolites results from heterolytic dissociative adsorption on acid-base pairs yielding Bronsted acid centers and alkyl groups bonded to zinc. The subsequent degradation of the alkyl fragments leads to the formation of zinc hydrides or gallium dihydrides and olefins. The oligimerization of olefins in the case of ZnZSM-5 can occur on both acidic hydroxyl groups produced via paraffin dissociation and on the Zn2+ cations per se already at ambient temperature. In the case of GaZSM-5, the appearance of Bronsted sites in the catalyst is achieved via incomplete replacement of OH groups with gallium cations.

Polymeric inhibitors of hydrogen sulfide corrosion

Abstract: The aggregation properties of hydrophobized polyethyleneimines and their inhibitory activity in hydrogen sulfide and carbon dioxide corrosion of iron were studied. The critical association concentrations, the radii of polymer aggregates formed in aqueous and aqueous alcohol solutions of polyethyleneimines, were determined. It was shown that these polymers at a concentration of 10–25 mg/l display a high inhibiting activity in the reaction of hydrogen sulfide corrosion of iron.

IR and 1H NMR assessments of the biodegradation of oil

Abstract: Comparative estimates of the degree of biodegradation of soil-polluting petroleum hydrocarbons with the use of IR and 1H NMR spectroscopy are given.

Hydroalkylation of benzene and ethylbenzene over metal-containing zeolite catalysts

Abstract: The hydroalkylation reaction of benzene and ethylbenzene over BEA zeolites with a Si/Al ratio of 9–190, MOR with Si/Al = 48, and MFI with Si/Al = 25 containing ruthenium, rhodium, platinum, or palladium was studied, as well as over the Ru/BEA zeolites with Si/Al = 42 doped with a second metal: nickel, cobalt, or rhodium. The catalytic experiments were conducted under flow conditions in the temperature range 130–190°C, a pressure of 1 MPa, a feed weight hourly space velocity of 2–64 h−1, and a stoichiometric reactant ratio. It was shown that the main reaction routes are the complete hydrogenation of benzene and ethylbenzene yielding cyclohexane and ethylcyclohexane, respectively; hydroalkylation yielding cyclohexylbenzene, para- and meta-ethylcyclohexylbenzenes, and diethylcyclohexylbenzenes; and alkylation resulting in dicyclohexylbenzenes and ethyldicyclohexylbenzenes. The ruthenium-promoted (1 wt %) zeolite BEA with Si/Al = 42 displayed the highest activity and selectivity in the benzene and ethylbenzene hydroalkylation reactions. Doping of the catalyst with cobalt and rhodium did not improve its catalytic properties, presumably, owing to the fact that the dopant metals largely occur in the cationic form according to the IR data for adsorbed CO. An admixture of nickel (0.5 wt %) to the catalyst increases the catalyst operation stability without reducing the yield of ethylcy-clohexy lbenzenes.

The features of the catalytic synthesis of methanethiol from dimethyl sulfide

Abstract: The characteristic features of methanethiol synthesis from dimethyl sulfide and H2S in the presence of Al2O3 at atmospheric pressure and T = 320–500°C have been studied. It has been shown that the yield of methanethiol increases with an increase in the temperature, the H2S-to-dimethyl sulfide ratio, and the contact time, attaining equilibrium values. The methanethiol formation rate is proportional to the dimethyl sulfide partial pressure raised to a power of 0.4 and the H2S partial pressure raised to a power of 0.8. An increase in the specific surface area and the volume of transport pores and a decrease in the particle sizes of Al2O3 facilitate the augmentation of the catalyst activity in methanethiol formation. At T ∼ 400°C, a low H2S concentration, and a long contact time, the side reaction of dimethyl sulfide cracking occurs to result in the release of methane and the deposition of sulfur-containing and carbonaceous compounds on the surface, which lower the activity of alumina. The deactivated catalyst can be regenerated by oxidation.

Decalin ring opening reactions on ruthenium-containing zeolite MCM-41

Abstract: Ruthenium catalysts supported on the mesoporous carrier MCM-41 were synthesized and characterized. It was found that the presence of the metal markedly accelerated decalin ring opening reactions as compared to the acid support alone, and it increases the selectivity owing to inhibition of protolytic cracking. It was shown that activity of ruthenium catalytic systems is lower than that of platinum catalysts supported on MCM-41 and much lower than the activity of platinum on zeolites. The low activity of catalytic systems based on the mesoporous support MCM-41 is due to its substantially lower acidity in comparison with zeolites beta and Y. Thus, it is concluded that the use of MCM-41 in decalin ring opening reactions is limited even in the presence of the metal, first of all, because of the low acidity of the support.

Carboxylation of organic compounds with metal alkyl carbonates (review)

Abstract: Published data on the carboxylation of organic compounds with salts of alkyl carbonic acids (metal alkyl carbonates) are surveyed.

Catalysis of limonene oxidation by cationic surfactants in combination with transition metal acetylacetonates

Abstract: The joint action of cationic surfactants and transition metal acetylacetonates on the oxidation of limonene (1-methyl-4-isopropenyl-1-cyclohexene) was studied. All mixed compositions exhibited a synergistic effect, i.e., the oxygen absorption rate in the presence of both components was several times the sum of the rates of oxidation catalyzed by the surfactant alone and the transition metal compound alone. The strongest synergistic effect was observed for the CTABr-Co(II) and CTACl-Cu(II) combinations. A detailed study of the limonene oxidation kinetics in the presence of CTABr and Co(acac)2 has shown that the synergy mechanism consists in that Co(acac)2 and the primary oxidation product hydroperoxide form mixed micelles in which hydroperoxides are activated and Co(acac)2 is concentrated.

Assessment of the competitiveness of the radical and nonradical mechanisms in the acid-catalyzed oxidation of styrene epoxide

Abstract: The oxidizability value of styrene epoxide as the ratio k 2/√k 6, where k 2 and k 6 are the propagation and termination rate constants of the epoxide oxidation chain, respectively, was calculated from experimental data on the oxidation of neat styrene epoxide with oxygen in the presence of the initiator dicumyl peroxide in a quartz reactor of a manometric unit. Alternative calculations of the oxidizability value with the use of two procedures and two experimental setups yielded close values of k 2/√k 6 = 0.333exp(−22.5 kJ mol−1/RT) and k 2/√k 6 = 0.18exp(−22.1 kJ mol−1/RT)(l/(mol s))1/2 (393–413 K), which characterize a quite high stability of styrene epoxide toward oxidation by peroxide radicals. With allowance for the new data, it was concluded that the radical mechanism is unfeasible under the conditions of the earlier-studied mild acid-catalyzed oxidation of styrene epoxide (333–348 K).

Catalytic transformations of mono- and bis-silyl substituted norbornadienes

Abstract: Transformations of 2-trimethylsilylnorbornadiene-2,5 (SNBD) and 2,3-bis(trimethylsilyl)norbornadiene-2,5 (DSNBD) under metathesis and addition polymerization conditions were studied. In the presence of the WCl6/1,1,3,3-tetramethyldisilacyclobutane-1,3 and Cl2(PCy3)2Ru=CHPh catalysts, high-molecular-mass silicon-substituted poly(cyclopentylidene vinylene)s were obtained with yields up to 98%. Under addition polymerization conditions, SNBD and DSNBD dimerized on the nickel(II) naphthenate-methyl alumoxane catalyst to give pentacyclic dimers. Three dimers were detected in the case of SNBD, whereas the exo-trans-exo-cyclodimer alone was exclusively produced from DSNBD. Being inactive in addition homopolymerization, both SNBD and DSBND take part in addition copolymerization with norbornene.

Selective hydrogenation on palladium-containing catalysts of byproduct phenylacetylene present in industrial fractions of styrene

Abstract: The process of liquid-phase hydrogenation of the phenylacetylene byproduct in the industrial styrene fractions formed in different styrene manufacture stages at OAO Salavatnefteorgsintez was studied on specimens of the palladium-containing G-58E, APKGS-20E2, and KSVK catalysts. It was found that the KVSK catalyst, which is a silica glass-fiber matrix containing 0.2 wt % of dispersed palladium, was the most effective in the selective hydrogenation at atmospheric pressure and temperatures of 20–30°C of phenylacetylene present in the industrial fractions of styrene. It was shown that the minimal loss of styrene is attained in the case of phenylacetylene hydrogenation in the hydrocarbon condensate fraction.

Comprehensive analysis of diesel hydrotreating feedstock

Abstract: Comprehensive analysis of the physicochemical properties of petroleum fractions, components of hydrotreater feedstock for manufacturing diesel fuel, was performed. Twenty two fractions, of which 14 are straight-run oil distillates, six are products of thermal and thermocatalytic processes, and two fractions represent mixed hydrogen-treatment feedstock, were studied. The fractional composition, the density, the refractive index, the sulfur content, the total concentration of aromatic hydrocarbons, and the amounts of sulfonatable compounds and aromatic hydrocarbons of different classes were determined. The group composition of sulfur compounds in feedstock sources and in the mixed hydrotreater feedstock was determined. The influence of the quality of hydrotreating feedstock on the residual sulfur content in the hydrogenation product was shown for industrial conditions.

Manufacturing of alkylate gasoline on the polycation-decationated form of nickel-and cobalt-promoted zeolite Y

Abstract: The synthesis of alkylation catalysts based on ultrastable zeolites Y in the polycation-decationated form promoted with the transition metals nickel and cobalt is described, and the results of catalyst testing in the alkylation of the recycle fraction for the manufacturing of oligomer gasoline are presented.

Effect of photoirradiation on the antioxidant properties of secondary resins and asphaltenes

Abstract: The consequences of photoirradiation of resins and asphaltenes from the heavy catalytically cracked gas oil fraction of a vacuum distillate and heavy pyrolysis tar of straight-run gasoline from Baku crude oil were studied by IR spectroscopy. It was found that exposure to light results in intramolecular rearrangement, leading to the formation of stable polycondensed aromatic functional quinonoid and phenolic structures which exhibit an antiradical activity. The effect of enhancement of the inhibiting activity of resins and asphaltenes as a result of photoirradiation is illustrated by the model test reaction of polystyrene oxidation.

Aluminosilicate-supported cobalt catalysts in the Fischer-Tropsch synthesis

Abstract: Cobalt catalysts supported on SIRAL aluminosilicates have been prepared and tested in hydrocarbon synthesis from CO and H2. It has been shown that the state of the cobalt metal on the catalyst surface is determined by both the cobalt content and the support nature, in particular, by the phase composition on its surface. The reaction rate on cobalt crystallites 3–6 nm in size is lower than that on 8–13-nm crystallites. It has been found that promotion with cerium oxide considerably increases the catalyst activity, although the selectivity for C5+ hydrocarbons slightly decreases.

Synthesis of ethylbenzene on zeolite catalysts

Abstract: Scaling of the process for zeolite-catalyzed ethylbenzene synthesis used as an example is shown, and the catalyst characteristics and product yields are given. The properties of the catalysts and their stability were studied in laboratory, micro-pilot, pilot, and demonstration units with reactor volumes of 0.01, 1, 100, and 1000 dm3, respectively, a sequence that, in combination with the selection of an optimal catalyst, made it possible to determine more exactly the role of each scaling level. The design of the last reactor was practically identical to that of the industrial reactor. The results of the experiments showed that the product quality and the catalyst service life were the same in the pilot and demonstration reactors operating at identical temperatures, feedstock compositions, and olefin space velocities. To confirm the results under conditions identical to those of an industrial reactor and to devise a mathematical model of the process, the pilot and demonstration units used were designed in such a manner that the basic engineering principles of the industrial reaction could be verified. As a result, the domestic technology of industrial-scale ethylbenzene production on heterogeneous catalysts was implemented.

Esterification of petroleum naphthenic acids with acetylenic alcohols

Abstract: The reversible esterification reaction of petroleum naphthenic acids with acetylenic alcohols in the presence of homogeneous and heterogeneous acid catalysts was investigated. The optimal parameters of the process were determined and its kinetic features were investigated. It was found that propargyl alcohol is more reactive than its dimethylated analog. It was shown that propargyl esters of petroleum naphthenic acids can be used as anticorrosive additives for motor oils.

Hydroisomerization of n -octane on platinum-containing micro-mesoporous molecular sieves

Abstract: The hydroisomerization reaction of n-octane at atmospheric pressure and a temperature of 230°C on platinum-containing catalysts with a combined micro-mesoporous structure synthesized on the basis of MOR and BEA zeolites was studied. The influence of the nature of zeolite, the relative amount of micropores, the platinum content, and the Si/Al ratio on the catalytic activity was examined. The microporous materials showed a considerably higher n-octane conversion and a higher isomerization selectivity as compared to both starting zeolites and mesoporous catalysts. It was found that the BEA-based micro-mesoporous materials are more active and selective than mordenites. An increase in platinum loading from 0.2 to 0.7 wt % leads to a rise in the yield of octane isomers, and a further increase in the platinum content does not result in a substantial change in the characteristics of the processes. It was shown that a change in the Si/Al ratio has a considerable effect on the formation of polybranched C8 isomers.