Carboxylation of <Emphasis Type="Italic">o</Emphasis>-, <Emphasis Type="Italic">m</Emphasis>-, and <Emphasis Type="Italic">p</Emphasis>-chlorophenols with sodium ethyl carbonate

The possibility for the synthesis of 5-chloro-2-hydroxybenzoic, 4-chloro-2-hydroxybenzoic, and 3-chloro-2-hydroxybenzoic acids via regioselective carboxylation of p-, m-, and o-chlorophenols, respectively, with sodium ethyl carbonate has been demonstrated. Simple and convenient procedures developed in this study for the synthesis of chlorohydroxybenzoic acids can be used for their preparative and industrial synthesis.     

Conversion of <Emphasis Type="Italic">n</Emphasis>-butane to isoparaffins over modified mordenite-zirconia catalysts

The catalytic properties of modified mordenite-zirconia catalysts in the conversion of n-butane to isoparaffins have been investigated. It has been shown that the modification with nickel, cobalt, and sulfate ions increases the activity of the mordenite-zirconia catalysts, thereby making it possible to lower the temperature of the process to 190–220°C. At lower temperatures, dilution with hydrogen retards the formation of isoparaffins.     

Oxidative transformations of <Emphasis Type="Italic">p</Emphasis>-chloro- and <Emphasis Type="Italic">p</Emphasis>-fluorostyrene epoxides in the presence of <Emphasis Type="Italic">p</Emphasis>-toluenesulfonic acid

Mild oxidation of two halogenated styrene epoxides, 2-(4-chlorophenyl)oxirane (CSE) and 2-(4-fluorophenyl)oxirane (FSE), was studied in the presence of p-toluenesulfonic acid (TSA). Hydrogen peroxide and p-chlorobenzaldehyde are the products of CSE oxidation. The kinetics of the overall CSE consumption and oxidation of CSE and FSE are identical to those revealed earlier for the oxidation of styrene epoxide (SE). The consumption and oxidation rates do not depend on the epoxide concentration (zero order) and are proportional to the TSA concentration. At 343 K, the oxidation rate of CSE and FSE are higher than that for SE by factors of 2 and 7, respectively. The introduction of the halogen atoms in the p-position on the phenyl ring accelerates the oxidation.     

Oxidation of isopropylbenzene to hydroperoxide in the presence of <Emphasis Type="Italic">N</Emphasis>-hydroxyphthalimide

The features of the aerobic oxidation of isopropylbenzene to hydroperoxide have been studied using N-hydroxyphthalimide as the catalyst in different devices: recycle flow, bubble, and model reactor units, using both chemically pure and technical-grade isopropylbenzene. A computer model of the isopropylbenzene oxidation and hydroperoxide recovery units has been created as applied to coproduction of phenol and acetone. The technological parameters for isopropylbenzene oxidation in the absence of catalyst (industrial process) and in the presence of N-hydroxyphthalimide have been calculated.     

Hydroisomerization of <Emphasis Type="Italic">n</Emphasis>-octane on platinum-containing micro-mesoporous molecular sieves

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.     

Selecting an optimum catalyst for producing <Emphasis Type="Italic">para-tert</Emphasis>-butylphenol by phenol alkylation with <Emphasis Type="Italic">tert</Emphasis>-butanol

Results of testing various heterogeneous catalysts in the synthesis of p-tert-butylphenol via phenol alkylation with tert-butyl alcohol are presented. It has been shown that all other conditions being equal, zeolite beta produced by the Angarsk catalyst and organic synthesis plant possesses the highest catalytic activity and selectivity for the desired product.     

Investigation on the Effect of Microalgae <Emphasis Type="Italic">Chlorella</Emphasis> sp. and <Emphasis Type="Italic">Spirulina</Emphasis> on Biodiesel Production

The aim of this study is to investigate the production of biodiesel from two kinds of microalgae Chlorella sp. and Spirulina platensis. Various items such as culture, lipid extraction and the production of biodiesel have been studied. The results showed that the rapid growth of Chlorella sp. from 0.2 to 0.5 gr per liter productivity biomass of cultivation is more suitable than Spirulina microalgae with slow growth of 0.1 to 0.3 gr per liter for the productivity biomass of culture. In comparison to 26.2% lipid content of microalgae Chlorella sp., Spirulina microalgae lipid content and the amount of 14.3 indicate a significant difference. Biodiesel output value was 28.2% by direct transesterification method. According to the results, it could be argued that microalgae Chlorella sp. features make the most suitable microalgae species for biodiesel production. These features include: rapid growth and high productivity, biomass and suitable lipid contents, environmentally easier cultivation rather than other species, suitable fatty acid profiles, having the most common fatty acids compounds (as C14:0, C16:0 and C18:0) in biodiesel. Extraction method had the best performance of extraction by the biomass Bligh and Dyer method.     

Antiwear and extreme pressure properties of <Emphasis Type="Italic">N</Emphasis>-substituted dithiazacycloalkanes in mineral oils

Antiwear and extreme pressure properties of N-substituted 1,3,5-dithiazinane and 1,5,3-dithiazepanes obtained via the cyclothiomethylation of amines (monoethanolamine, propylamine) with formaldehyde and SH acids (H₂S, 1,2-ethanedithiol), taken in an amount of 3 wt %, in mineral oils have been studied.     

Isomerization of <Emphasis Type="Italic">n</Emphasis>-hexane over bifunctional Pt/SO<Subscript>4</Subscript>/ZrO<Subscript>2</Subscript> catalysts

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.     

Influence of the metal atom nature on the efficiency of ethylbenzene oxidation inhibition by Copper(II), Cobalt(III), and Lead(II) <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethyldithiocarbamates mixed with amines

The joint inhibiting effect of heavy metal N,N-diethyldithiocarbamates M(dtc) _n , where M = Cu(II), Co(III), or Pb(II), and three aromatic amines (1: 1) in the initiated oxidation of ethylbenzene with oxygen at 75°C has been examined. The synergistic inhibitory effect of 1: 1 M(dtc) _n -amine pairs strongly depends on the nature of the metal atom and the chelate unit structure of the metal dithiocarbamate. For most couples, the formation of new Cu(II), Co(III), and Pb(II) complexes of the [M(dtc) _n -amine] type in chloroform via coordination of the amine donor atom to the metal has been proved spectrophotometrically. Possible routes of oxidation chain termination by the newly formed complexes have been established.     

Catalytic Cracking of <Emphasis Type="Italic">n</Emphasis>-Hexane and <Emphasis Type="Italic">n</Emphasis>-Heptane over ZSM-5 Zeolite: Influence of SiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Ratio

The performance of two types of ZSM-5 zeolite catalysts (MFI-type zeolite, SiO₂/Al₂O₃ = 50 and 300) was studied in the catalytic cracking of n-hexane and n-heptane as a model compound of light naphtha for production of light olefins at 500, 550, and 600°C. The physicochemical properties of ZSM-5 catalysts were characterized by means of XRD, BET, SEM and NH₃-TPD. The influence of SiO₂/Al₂O₃ molar ratio was investigated on conversion and product selectivity. ZSM-5 zeolite yielded higher conversion in the cracking of n-hexane compared to n-heptane and maximum conversion was achieved over ZSM-5(50) at 600°C. ZSM-5(50) showed higher alkane selectivity rather than olefins. It was found that ZSM-5(300) was more desirable in terms of having significant selectivity to light olefins as well as producing high propylene to ethylene ratio. The maximum propylene to ethylene ratio of 2.7 and 2.48 was observed over ZSM-5(300) at 500°C for n-hexane and n-heptane cracking, respectively.     

Direct synthesis of <Emphasis Type="Italic">N</Emphasis>-acylpyrrolidines from tetrahydrofuran and nitriles of aliphatic and aromatic acids on zeolite catalysts under supercritical conditions

The tetrahydrofuran-nitrile (CH₃CN, n-C₄H₉CN, C₆H₅CN)-zeolite (faujasites, mordenite, beta, pentasils) system and its transformations under supercritical conditions were studied. The feasibility of direct synthesis of the corresponding N-acylpyrrolidines from THF and nitriles of aliphatic and aromatic acids was shown for the first time. The dependence of the THF reaction with nitriles on the temperature, the reaction time, the nature of the exchanged cations in zeolite, the type of zeolite, and the catalyst pretreatment conditions was revealed. Acid zeolites were shown to exhibit a high catalytic activity. The yield of N-acylpyrrolidines at 350°C in the presence of the most active catalysts (HNaY and HCaLnY) was 10–40% at a selectivity of up to 80%. The key role of H₂O was found, and a two-step scheme of the process, including the hydrolysis of nitrile to amide and the reaction of the latter with tetrahydrofuran resulting in the formation of N-acylpyrrolidine, was proposed.     

Heterogeneous catalytic conversion of glycerol with <Emphasis Type="Italic">n</Emphasis>-butyl alcohol

The etherification of glycerol with n-butyl alcohol at 140°C in the presence of sulfonated cation-exchange resins and zeolite catalysts in an autoclave reactor has been studied. It has been shown that styrene—divinylbenzene ion-exchange resins are effective catalysts for the production of glycerol n-butyl ethers: the glycerol conversion is about 98% with an n-butyl ether selectivity of about 88 mol % (140°C, 5 h, 5 wt % Amberlyst 36 catalyst, and 10 wt % glycerol in n-butanol). Zeolites Y and β in the H⁺ form exhibit comparable specific activity (glycerol conversion of no more than 25% under similar conditions) in combination with high selectivity for glycerol di-n-butyl ethers (up to 28%).     

Isomerization of <Emphasis Type="Italic">n</Emphasis>-hexane on binder-free shaped platinum-containing mordenite

A catalyst has been prepared as binder-free shaped MOR-type zeolite in the H form promoted with 0.5 wt % platinum, and n-hexane conversion over this catalyst has been studied. It has been found that the selectivity for C₄–C₆ isoparaffins on the new catalyst is about 90% at 300°C, a feed space velocity of 1.5 h^–1, and a hydrogen pressure of 3 MPa, with the hexane conversion being 80.0–83.0 wt % and the selectivity for isohexane making 83.0–86.0%. It has been shown that the new catalyst is stable for 50 h on-stream under these conditions.     

Conversion of higher <Emphasis Type="Italic">n</Emphasis>-alkanes under deep catalytic cracking conditions

The product distribution for the deep catalytic cracking of C₁₆-C₂₈ n-alkanes has been studied. Using the method of the temperature-programmed desorption of ammonia, the difference in the acid properties of HZSM-5 and ultrastable Y zeolites and the catalyst matrix components has been found. For the primary cracking of heavy hydrocarbon feedstock to occur, the catalyst matrix must have a high acidity. Bizeolite catalysts exhibit high selectivities for olefins with both normal and branched chains, which are due to a decrease in the contribution of the hydrogen redistribution reaction. For a bizeolite catalyst, the additivity of the selectivities for olefins and aromatic hydrocarbons, depending on the composition of the zeolite component, is observed.     

Catalytic reforming of <Emphasis Type="Italic">n</Emphasis>-heptane on platinum-tungsten supported on gamma-alumina

The mono-metallic and bi-metallic catalysts have been prepared by impregnating with solutions containing a compound of H₂PtCl₆, WO₃ and 1 ml HCl (0.1 mol). It should be noted that the catalysts’ activity and selectivity have been determined under these conditions: 450–500°C, and 15–25 atm by H₂. For converting n-heptane, the molar ratio H₂/C₇H₁₆ is 5, and LHSV is 1.5 ml/h. It has been proved that, under these experimental conditions, the conversion of n-heptane into branched aliphatic isomers is catalyzed by a bifunctional mechanism. The results indicate that in the presence of W, the catalysts have much higher selectivity and stability for isomerization reaction. At a given conversion, the bi-metallic catalysts produce much lower concentrations of cracked products. According to the tests, W modifies the support acidity resulting to the higher selectivity for isomerization and the lower one for cracking, and it also modifies the Pt properties.     

The catalytic properties of tungstated zirconia in <Emphasis Type="Italic">n</Emphasis>-heptane isomerization

The catalytic properties of zirconia modified with different amounts of tungstate anions in the hydroisomerization of n-heptane and its mixtures with benzene or toluene have been studied. It has been found that at a low temperature of 170°C, the yield of isoheptanes reaches 62.8% with a fairly high selectivity of 87.6% on the Pt/WO₄²⁻/ZrO₂ catalyst prepared by impregnation to contain 17.6 mol % tungstate anions. Under the same conditions, the yield of isoheptanes on a sulfated Pt/SO₄²⁻/ZrO₂ catalyst is as low as 14.0% with a selectivity of 20.3%. The hydroisomerization process effectively occurs on the tungstated catalyst in the presence of benzene or toluene.     

Thermal transformations of 4-<Emphasis Type="Italic">tert</Emphasis>-butylbiphenyl

The thermal stability of 4-tert-butylbiphenyl was studied in the range of 703–763 K. The competition of the cracking and isomerization reactions of alkyl substituents on the aromatic ring of the reactant and its products has been revealed. The kinetic characteristics of the complex of transformations occurring in the system have been determined. Recommendations are provided regarding the conditions for the determination of the critical parameters of 4-tert-butylbiphenyl and for the processing and use of compounds with a tert-butyl moiety in the molecule.     

Isomerization of <Emphasis Type="Italic">n</Emphasis>-hexane on platinum,palladium, and nickel catalysts deposited on columnar montmorillonite

Data on n-hexane hydroisomerization over Pt, Pd, and Ni catalysts deposited on aluminum-pillared Taganskoe montmorillonite are presented. The activity of the catalysts is compared with the acidity of the specimens and their physicochemical characteristics. It was shown that metals deposited on activated montmorillonite form metal-deposited systems with a uniform distribution of finely divided particles. The size of the palladium particles is about 1.5 times that of platinum.