Alcohol formation from synthesis gas: A thermodynamic study

A thermodynamic study is presented for the simultaneous synthesis of C₁–C₄ alcohols from synthesis gas. The equilibrium composition was calculated for the gaseous mixture containing Co, H₂, CH₃OH, C₂H₅OH, C₃H₇OH, n-C₄H₉OH and H₂O. Operating industrial conditions were specifically considered.

---

C₁–C₄ -. , CO, H₂, CH₃OH, C₂H₅OH, C₃H₇OH, -C₄H₉OH H₂O. .

     

Oxidative dehydrogenation of n-butenes: Product effect in the reactions over tin-antimony mixed oxides

The addition of possible oxidation and/or isomerization products (butadiene, water, isomeric n-butenes) resulted in neither promotion nor inhibition in the oxidative dehydrogenation of n-butenes over tin-antimony mixed oxide catalysts. On the basis of these and other information on the influence of products an interpretation has been given to complete the reaction mechanism more realistic than those based on previous experimental results.

---

(, ) ( -) , . , , .

     

Effect of iron on the properties of supported Rh?Fe catalysts. Rh?Fe/SiO2 catalysts

The state of metals in Rh–Fe/SiO₂ catalysts has been examined. Iron is shown to form clusters with rhodium, whose size and composition depend on the metal ratio in the catalyst. The structure of active sites affects the amount and adsorption heat of hydrogen and carbon monoxide and their interaction mechanism.

---

Rh–Fe/SiO₂-. , , . , CO .

     

Thermal study of some sulphosuccinates

The thermal properties of some sulphosuccinates and their intermediates were studied by using combined dynamic thermal analysis and mass spectrometry. The temperature ranges were similar in the two methods, and a scheme of thermal decomposition of the compounds investigated was suggested. In the first temperature range of thermal decomposition of the sulphosuccinate a-rupture of the molecular ion occurs. In the second temperature range, the fragmentation proceeds in two directions: either-rupture of the ethoxylated nonylphenol, or-rupture of the acid residue of the sulphosuccinates.

---

Zusammenfassung Mittels einer Kombination von dynamischer Thermoanalyse und Massenspektroskopie wurden die thermischen Eigenschaften einiger Sulfosukzinate und deren Zwischenprodukte untersucht. Im ersten Temperaturbereich der thermischen Zersetzung des Sulfosukzinates findet eine-Spaltung des Molekülions statt. Im zweiten Temperaturbereich tritt auch ein alternativer Fragmentierungsweg auf: eine-Spaltung des Säurerestes des Sulfosukzinates.

---

- . . - -. : - - .

     

Novel evidence for the selective behaviour of tungsten carbide in liquid phase heterogeneous catalytic hydrogenation

Liquid (aqueous) phase catalytic hydrogenation of compounds containing two oxo-groups in -position (biacetyl, glyoxal, alloxan) was studied in the presence of tungsten carbide catalyst. It has been shown that only one of the oxo-groups is affected in the course of the process and is transformed into a >CH–OH group. Comparative studies carried out in the presence of platinum catalyst attest the selective behaviour of tungsten carbide.

---

- - (, , ). , >C=O >CH–OH, . .

     

Silylation of porous glass supported platinum catalysts

Effect of silylation with hexamethyldisilazane on adsorption and catalytic properties of porous glass-supported platinum catalysts has been studied. Catalytic activity decreases markedly with an increase in surface coverage by trimethylsilyl groups for all the following reactions examined: hydrogenation of benzene, dehydrogenation of cyclohexane and dehydrocyclization of n-hexane.

---

, . , : , -.

     

Selectivity of Fischer-Tropsch synthesis on supported nickel catalysts

Alumina supported Ni as well as Ni²⁺ exchanged CaNaX zeolites were used to study Fischer-Tropsch synthesis. Two significant selectivity effects can be distinguished, which are related to the different structures and acidities of the catalysts.

---

CaNaX, Ni, Ni⁺² , -. , .

     

The thermal properties of carbon-silica adsorbents (carbosils) prepared by methylene chloride pyrolysis

The thermal properties of complex carbon-silica adsorbents (carbosils) were investigated using differential thermal analysis. The adsorbents were prepared by pyrolysis of methylene chloride. Pyrolysis reaction on silica surface was carried out at different temperatures (400–700 °C) and at different pressures of CH₂Cl₂ vapours. Thermal analysis was carried out in air atmosphere. The following parameters characterizing the properties of the adsorbents were determined: carbon content, specific surface area, carbon layer thickness, pore volume, mean pore radius, differential of heats of adsorption ofn-hexane and benzene, and micrographs. The correlation between topography and morphology of carbon deposits (dependent on the parameters of the pyrolysis process) and the courses of DTA and TG curves corresponding to individual carbosils have been determined.

---

Zusammenfassung Mittels DTA wurden die thermischen Eigenschaften von komplexen Kohlenstoff-Silikaadsorptionsmitteln (Carbosil) untersucht. Die Adsorptionsmittel wurden durch Pyrolyse von Methylenchlorid gefertigt. Die Pyrolyse wurde an der Oberfläche von Silika bei verschiedenen Temperaturen (400–700 °C) und bei verschiedenen CH₂Cl₂-Drücken durchgeführt. Die Thermoanalyse geschah in Luftatmosphäre. Folgende Parameter zur Charakterisierung der Eigenschaften der Adsorbenten wurden ermittelt: Kohlenstoffgehalt, spezifische Oberfläche, Kohlenstoffschichtdicke, Porenvolumen, Porendurchmesser, Ableitung der Adsorptionswärme vonn-Hexan und Benzol sowie Oberflächenmikrogramme. Es konnte der Zusammenhang zwischen Topografie und Morfologie der Kohlenstoffablagerungen (abhängig von den Parametern des Pyrolysevorganges) sowie dem Verlauf der DTA- und TG-Kurven der entsprechenden Carbosile festgestellt werden.

---

- (). . (400–700°) . . : , , , , - , . , , .

     

Thermal analysis of poly(methyl methacrylate)-copper composite

Thermal characteristics of the composites of poly(methyl methacrylate) and copper are reported, including the order of reaction and activation energy of the major second stage of pyrolysis. The randomly-distributed metal particles in the polymer matrix can form paths for heat transfer which determine the mechanism of thermal degradation.

---

Zusammenfassung Die thermischen Charakteristika der Verbindungen von Polymethylmethacrylat mit Kupfer werden zusammen mit der Reaktionsordnung und der Aktivierungsenergie der grösseren zweiten Stufe der Pyrolyse beschrieben. Die zufallsbestimmt verteilten Metallpartikel in der Polymermatrix können Wege des Wärmetransfers formen, welche den Mechanismus der thermischen Zersetzung bestimmen.

---

Résumé On décrit les caractéristiques thermiques de composites du polyméthylméthacrylate avec le cuivre, parmi lesquelles l'ordre de réaction et l'énergie d'activation de la seconde étape de la pyrolyse qui est la principale. Les particules du métal distribuées au hasard dans la matrice du polymère peuvent constituer des voies pour le transfert de chaleur qui déterminent le mécanisme de la dégradation thermique.

---

, . , .

     

Analysis of thermal desorption spectra of oxygen desorbed from rhodium

Thermal desorption spectra of oxygen desorbed from rhodium have been analyzed in terms of models accounting for the effect of lateral interactions between adsorbed particles and of their diffusion into the bulk of metal on the desorption kinetics of O₂. Complex configuration of these spectra is ascribed to the processes of formation/decomposition of surface Rh oxides and the diffusion of particles into the near-surface layers of metal and back to the surface.

---

- , O₂ . - O₂ Rh - .

     

Исследование роли фосфиновых комплексов никеля различных степеней окисления в каталитической димеризации олефинов

Ni(II), Ni(I) Ni(O) . , , , Ni(O) Ni(I) - Ni(I) Ni(II) Ni(O).

---

The interaction of organoaluminium compounds with phosphine complexes of Ni(II), Ni(I) and Ni(0) has been studied under the conditions of catalytic propylene dimerization. The active complexes are formed from Ni(II) compounds, the regeneration of the latter is ensured by repeated reduction, oxidation of Ni(0) to Ni(I), and by disproportionation of Ni(I) into Ni(II) and Ni(0).

     

Acid properties and stability of operation of vanadium catalysts in benzene oxidation to phenol

Catalytic properties of V₂O₅/SiO₂ in benzene oxidation by N₂O were examined. Sodium additive was shown to affect the catalyst operation stability.

---

V₂O₅/SiO₂ N₂O. .

     

Kinetics of deuterium isotope exchange between thiophenol or t-butylthiol and i-propylthiol

The rate constants and activation energies of bimolecular deuterium exchange in the systems: C₅H₅SD+i-C₃H₇SH and t-C₄H₉SD+i-C₃H₇SH in dilute C₆H₁₂ solutions have been established. The concerted H-transfer inside the cyclic dimer with two H-bonds formed in these systems is probably the rate-limiting step. The rate constant for H-transfer inside the cyclic dimer is independent of the acidic properties of the thiols.

---

: C₆H₅SD+i-C₃H₇SH -C₄H₉SD+i-C₃H₇SH C₆H₁₂. -, , , . .

     

m-Xylene conversion over dealuminated Y zeolites studied by the pulse method

m-Xylene conversion was studied over dealuminated Y type zeolites in hydrogen forms, SiO₂ to Al₂O₃ ratios were varied from 4.86 to 12.95.

---

- . SiO₂/Al₂O₃ 4,86 12,95.

     

Le calcul des parametres cinetiques des Reactions de Decomposition thermique a l'aide des donnees de l'analyse thermique differentielle

Résumé On a modifié la méthode différentielle pour le calcul des paramètres cinétiques des réactions de décomposition thermique du type: A_(s) B_(s) + C_(g), en utilisant les données de l'analyse thermodifférentielle. En effectuant le calcul des paramètres cinétiques des réactions de déshydratation de l'oxalate de calcium monohydraté et de décomposition du carbonate de calcium on obtient des résultats qui concordent d'une manière satisfaisante avec ceux obtenus par d'autres méthodes.

---

A modification of the differential method is presented in order to evaluate the kinetic parameters of thermal decomposition reactions of the type A _s B _s + +C_g, using differential thermal analysis (DTA) data. The kinetic parameters calculated for the dehydration and decomposition of calcium oxalate and carbonate agree satisfactorily with those mentioned in the literature.

---

Zusammenfassung Es wird über eine Abänderung der Differentialmethode zur Errechnung der kinetischen Parameter von thermischen Zersetzungsreaktionen des Typs A_(s) B_(s) + C_(g) mit Hilfe von differentialthermoanalytischen Daten berichtet. Die am Beispiel der Dehydratation des Calciumoxalat-Monohydrats und der Zersetzung des Calciumcarbonats erhaltenen Ergebnisse der auf angegebene Weise durchgeführten kinetischen Berechnungen stimmen gut mit den nach anderen Methoden erhaltenen Resultaten überein.

---

A_{(s) (s)} + C_(g), (). , , , .

     

Kinetic and mechanistic studies on the oxidation of sulfanilic acid by peroxomonophosphoric acid

Oxidation of sulfanilic acid to the corresponding azoxy derivative by peroxomonophosphoric acid (PMPA) has been studied in aqueous medium. The observed bell-shaped pH-rate profile has been rationalized on the basis of protonation of the amino group and ionization into different PMPA species and a suitable rate law has been proposed. The mechanism of oxidation involves the nucleophilic attack of nitrogen on the electrophilic peroxo oxygen.

---

- (PMPA) . pH— , PMPA . .

     

Formation of the active component of a vanadium complex catalyst for the oxidation of anthracene to anthraquinone

The phase composition in various stages of preparation of the active material coating the catalyst for the partial oxidation of anthracene to anthraquinone was studied. The presence of an active phase was evidenced in the final active material as well in a precursor.

---

, . , .

     

Thermal behaviour of melamine

Melamine undergoes condensation on heating with elimination of ammonia and formation of insoluble products. Thermogravimetry and infrared characterisation show that two products of successive condensation can be reproducibly obtained upon heating atT}<500 °C and then at 600 °C. Above 620 °C, the melamine condensate undergoes thermal degradation with quantitative formation of volatile products.

---

Zusammenfassung Melanin geht beim Erhitzen eine Kondensation unter Abgabe von Ammoniak und Bildung unlöslicher Produkte ein. Durch Thermogravimetrie und Infrarotspektroskopie wird gezeigt, daß beim Erhitzen zwei Produkte von aufeinanderfolgenden Kondensationsreaktionen beiT}<500 °C undT= 600 °C reproduzierbar erhalten werden. Oberhalb 620 °C wird das Melaminkondensat vollständig unter Bildung flüchtiger Produkte thermisch zersetzt.

---

. , . , 500°, — 600°. 620° .

---

---

The authors wish to thank Dr. N. Del Fanti of Mantefluos, Italy for most helpful discussion.

---

This work has been supported by the Consiglio Nazionale delle Ricerche through the Progetto Finalizzato Chimica Fine e Secondaria.     

Kinetics of thermal decomposition of pyrite in an inert atmosphere

The thermal decomposition of pyrite in an inert atmosphere was studied in order to obtain a detailed knowledge of the kinetics and mechanism of the reaction 2 FeS₂=2FeS+S₂, which is one of the methods of producing elementary sulphur. The process was studied under isothermal conditions at temperatures of 600, 660, 700, 750, 800 and 850 °C in a nitrogen atmosphere, by means of a thermobalance. The rate-controlling processes were determined and their kinetic parameters were calculated. The optimum temperature for the process was found to be 800 °C.

---

Zusammenfassung Es wurde die thermische Zersetzung von Pyrit in inerter Atmosphäre bestimmt, um detaillierte Informationen über Kinetik und Mechanismus der Reaktion 2 FeS₂=2FeS+S₂, einer der Darstellungsreaktionen von elementarem Schwefel zu erlangen. Der Vorgang wurde mittels einer Thermowaage unter isothermen Bedingungen bei Temperaturen von 600, 660, 700, 750, 800 und 850 °C untersucht. Es wurden die geschwindigkeitsbestimmenden Schritte bestimmt und deren kinetische Parameter errechnet. Als Optimumtemperatur für diesen Prozeß erwies sich 800 °C.

---

- 2FeS₂=2FeS + S₂, . 600, 660, 700, 750, 800 850 ° . , 800°.

     

Hydrogenation of xylenes over supported Pt catalysts. Influence of different variables on their catalytic activity

In this work we studied and compared the catalytic activity of various supported Pt systems on the gas-phase hydrogenation of o-, m- and p-xylene. We analyzed the influence of different catalyst preparation variables (solvent, precursor, salt, support and catalyst reduction temperature used) on the catalytic activity and selectivity towards the corresponding cis-and trans-dimethylcyclohexanes.

---

- o-, m- -. (, , ) - -.