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.     

Catalytic conversions of <Emphasis Type="Italic">n</Emphasis>-hexane and hydrocarbon mixtures on modified shungite rock

Using model catalytic reactions of n-hexane conversion and the conversions of both narrow and wide fractions of actual hydrocarbon mixtures, straight-run gasoline and gas condensate, as an example, it has been shown that modified type-III shungite rock (carbon content of 20–35%) from the Zazhogino deposit of Karelia at certain temperatures exhibited catalytic activity in the isomerization reaction of hydrocarbons with or without the insignificant formation of environmentally hazardous aromatic compounds. In the case of n-hexane and, especially, straight-run gasoline, the octane rating of the product increases.     

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.     

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.     

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.     

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.     

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.     

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.     

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%).     

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.     

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.     

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.     

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.     

Distribution of high-molecular-weight <Emphasis Type="Italic">n</Emphasis>-alkanes in paraffinic crude oils and asphaltene-resin-paraffin deposits

Paraffinic and high-paraffin oils and asphaltene-resin-paraffin (ARP) deposits of Samara oblast have been investigated by differential scanning calorimetry (DSC) and GLC techniques. High-paraffin oils have been found to contain n-alkanes with the number of carbon atoms of C₁₅-C₆₀ and higher forming a crystalline phase with the mp ∼30–40°C. The ARP deposits from high-paraffin oils almost do not contain highmolecular-weight n-alkanes with the number of carbon atoms >55. This is due to the peculiarities of the crystallization and cocrystallization processes of high polydispersity n-alkanes in crude oils.     

Distribution of <Emphasis Type="Italic">n</Emphasis>-Alkanes in the Products of Electric Dewaxing of Diesel Fuel

The distribution of n-alkanes in summer diesel fuel and products of its electric and urea dewaxing, dewaxed diesel (DWD) and slack wax, has been studied. Quantitative changes in the groups of low- C_7–14, middle- C_15–18, and high-melting C₁₉₊n-alkanes in the diesel, DWD, and slack wax have been shown. By the combination of the DWD yield, selectivity of removal of high-melting n-alkanes from the initial diesel fuel, and cold flow properties of DWD, electric dewaxing is a promising process.     

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.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-methylaniline over molecular sieve catalysts

The preparation of N-methylaniline in two various processes: alkylation of aniline with methanol and hydroalkylation of nitrobenzene with methanol has been studied. Bifunctional molecular sieves containing metal copper as the hydrogenating component and zeolites BEA, MOR, MFI, FAU (Y) and mesoporous material MCM-41 as an alkylating component were used as catalysts. It has been shown that the modification of samples with copper nitrate increases the number of Lewis acid sites and decreases the number of Brønsted acid sites as copper embeds into cation exchange positions. It has been determined that the catalyst modification with copper increases the activity and enhances the selectivity towards N-alkylated products.     

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.     

Effect of <Emphasis Type="Italic">n</Emphasis>-Paraffins on the Low-Temperature Properties of Aviation Diesel Fuel

Maximum depression of the cloud and solid points is attained as a result of reducing the content of high-boiling n-paraffins with the optimum content of low-boiling n-paraffins and monocyclic aromatic hydrocarbons. Addition of 10 wt. % kerosene to diesel fuel affects its low-temperature properties less than removal of the end cuts — above 360° C. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 28 – 31, November – December, 2005.