Comparison of activities of cracking catalysts containing ZSM-5 and Y-zeolite

Studies on the catalytic cracking of diesel oil fraction with the boiling range of 493–603 K on H-ZSM-5 and RE, H-Y zeolites has been carried out. The results show that in the presence of H-ZSM-5 zeolite no significant increase in the yield of gasoline is observed. Higher percentage of unsaturated hydrocarbons in the gasoline and gases indicates that the hydrogen transfer activity of H-ZSM-5 containing catalyst is lower than that of RE, H-Y zeolites.

---

H-ZSM-5 RE, H-Y , 493–603 . H-ZSM-5 . , , H-ZSM-5 , RE, H-Y .

     

Estimation of nonlinear relaxation of catalytic reactions

Nonlinear relaxation time has been considered as a differential characteristic determined by the reciprocal value of the relative decrease in the deviation rate of the current concentration vector of intermediates from that of their steady-state concentrations. This characteristic is used for the analysis of some model reactions.

---

, , .

     

Kinetics of perborate oxidation of quinol

The perborate oxidation of quinol in aqueous acetic acid is first order with respect to perborate, zero order with respect to quinol, and first order with respect to H⁺. The oxidation is faster than H₂O₂ oxidation. Breakdown of protonated perboric acid is suggested as the rate-limiting step.

---

, H⁺. . , , , .

     

Ethylene hydroformylation over a nafion-supported rhodium catalyst

Ethylene hydroformylation over a Nafion-supported rhodium catalyst has been studied under atmospheric pressure in the temperature range of 100–135 °C, using the transient response method.

---

, , 100–135°C, .

     

Calculation of the rate of SO2 oxidation to SO3

Approximate equation to calculate the effectiveness factor of catalyst for SO₂ oxidation to SO₃ has been derived. Calculated data agree well with those predicted by a quasi-homogeneous model.

---

. .

     

Collisional energy transfer in the decomposition of 2-methyloxetane and 3-methyloxetane, I. Gas/gas collisions

The pressure dependence of the unimolecular rate constants for the thermal decomposition of 2-methyloxetane and 3-methyloxetane has been studied. The average energy transferred downward in gas-gas collision was determined by the application of RRKM theory and a stepladder model of energy transfer.

---

2- 3-. , - , .

     

Studies on the Fe2(MoO4)3-V2O5 system

The phase equilibria established in solid state in the whole range of component concentrations in the Fe₂(MoO₄)₃-V₂O₅ system were studied by DTA and X-ray powder diffraction. This system is not a real two-component system.

---

Zusammenfassung Im gesamten Konzentrationsbereich der Komponenten des Systems Fe₂(MoO₄)₃-V₂O₅ wurde das im festen Aggregatzustand festgestellte Phasengleichgewicht mittels DTA und Pulverröntgendiffraktionsverfahren untersucht. Dieses System ist kein wirkliches Zweikomponentensystem.

---

F₂(₄)₃-V₂O₅ . , .

     

Effect of substituent on the mechanism of oxidation of anilines by acidic iodate. A kinetic study

The nature of the substituent is found to exhibit a profound influence on the mechanism of oxidation of anilides by iodate. The process appears to be smooth with electron-releasing groups, while it involves consecutive reactions with electron-withdrawing groups. Azobenzenes and quinones are obtained as the major products with electron-releasing and withdrawing groups, respectively.

---

. - , - . -, .

     

Methanol-based synthesis of hydrocarbons on bifunctional Y-type zeolites

The directions of methanol conversion on Pt, Pd, Zn, Ni metals and Y zeolites and on bifunctional metal-Y-zeolite catalysts have been studied. The increase of the hydrogenation activity of bifunctional catalysts enhances the rate of methanol conversion and decreases the selectivity of hydrocarbon formation.

---

- Y, - Y.

     

Thermogravimetric characterization of Quayarah heavy crude oils

Five heavy crude oil samples from the Quayarah field were thermally evaluated using two modes of thermogravimetry (TG): dynamic and programmed TG with heating and hold-up periods at 350 and 550°. The light and medium volatility fraction (L+M) appeared directly proportional to the metal content. In contrast, the heavy fraction (H) (350–550°) was inversely proportional to the metal content. This contradiction was attributed to the autocatalytic degradation of some of the heavy fraction into lighter species, which upgrades the crude with respect to the (L+M) fraction at the expense of the heavy fraction. The crudes were identical with regard to the ratio (L+M) to (H+R), whereR=residue, as a consequence of their identical API gravity and sulphur contents.The rate of degradative volatilization of the heavy fraction was measured by DTG, which indicated a direct correlation with the vanadium content as regards the onset temperatures and the DTG peak maximum.

---

Zusammenfassung Fünf vom Quayarah-Feld stammende schwere Rohöle wurden mittels dynamischer und programmierter TG mit konstanten Perioden bei 350 und 550 °C charakterisiert. Der Anteil der leicht- und mittelflüchtigen Fraktion (L+M) schien proportional, der der schwerflüchtigen Fraktion (H) (350 550°) dagegen umgekehrt proportional dem Metallgehalt zu sein. Dieser Widerspruch wurde dem autokatalytischen Abbau einiger der schwerflüchtigen Komponenten zu leichteren Spezies zugeschrieben, der zu einer Erhöhung des Anteils der (L+M)-Fraktion auf Kosten der schwerflüchtigen Fraktion führt. Die Rohöle waren wegen der gleichen API-Schwere und gleicher Schwcfclgehalle hinsichtlich des Verhältnisses von (L+M) zu (H+R) identisch (R=Rückstand). Die Geschwindigkeit der degradaliven Verflüchtigung der schweren Fraktion wurde mittels DTG gemessen, wobei sich eine direkte Korrelation zwischen dem Vanadingehalt einerseits und der Einsatztemperatur bzw. dem DTG-Peakmaximum andererseits ergab.

---

350 550°. (+ ) , () (350–550°) — . , . + +, — , . . , , .

     

X-ray study of palladium catalysts. Influence of thermal treatment in hydrogen on the phase composition

The thermal treatment of Pd catalysts in a reducing atmosphere of hydrogen leads to interaction of supported metal and support to form solid solutions.

---

, .

     

The measurement of meaningful activation energies

The uncertainty surrounding the significance of the measured kinetic parameters of solid state decomposition reactions is discussed briefly. Some suggestions are made about what precautions should be taken in order to favour the measurement of undistorted results. Some criteria are proposed for deciding whether a measuredE value can be considered to have its usual meaning. The results of a series of experiments aimed at measuring the activation energy of the decomposition of calcium carbonate using a variety of methods, sample sizes and experimental conditions are presented. These results are compared with results found in the literature and it is concluded that it is possible to measure a reproducible value forE and it is tentatively proposed that this value is meaningful in terms of the energy barrier model of chemical reaction kinetics.

---

Zusammenfassung Die sich auf die Signifikanz gemessener kinetischer Parameter von Zersetzungsreaktionen fester Stoffe beziehende Unsicherheit wird kurz diskutiert. Es werden einige Vorschläge hinsichtlich der Vorkehrungen unterbreitet, die zu treffen sind, um unverfälschte Meßergebnisse zu erhalten. Einige Kriterien werden vorgeschlagen, die geeignet sind zu entscheiden, ob ain gemessenerE-Wert die übliche Bedutung hat. Ergebnisse einer Reihe von Experimenten werden angegeben, die ausgeführt wurden, um die nach verschiedenen Methoden, bei Anwendung unterschiedlicher Probenmengen und unter verschiedenen Versuchsbedingungen für die Aktivierungsenergie der Zersetzung von CaCO₃ erhaltenen Werte zu vergleichen. Es wird gefolgert, daß es möglich ist, den Wert vonE reproduzierbar zu messen, und versuchsweise vorgeschlagen, diesen Wert als sinnvoll für das Energiebarrierenmodell der chemischen Reaktionskinetik anzusehen.

---

. , . , E . , , . . , .

     

51V NMR studies of systems V2O5-KHSO4 and V2O5?K2SO4

Systems V₂O₅–KHSO₄ and V₂O₅–K₂SO₄ have been studied by the⁵¹V NMR method. The first system demonstrates the same states of vanadium as the previously studied V₂O₅–K₂S₂O₇, in this system a compound with an equimolar ratio of components has been found. In V₂O₅–K₂SO₄ the state of vanadium differs from the above systems and the formation of a compound with V/K=4 is observed.

---

⁵¹V KHSO₄–V₂O₅ K₂SO₄–V₂O₅. , K₂S₂O₇–V₂O₅, . K₂SO₄–V₂O₅ V/K4.

     

Homogeneous decomposition of formaldehyde induced by a carbon dioxide laser

The homogeneous pyrolysis of formaldehyde has been studied under laser heating. At temperatures of 950–1000 K H₂CO decomposition is shown to be a radical chain reaction. Methanol formation in formaldehyde pyrolysis is a homogeneous reaction.

---

. , H₂CO 950–1000° . .

     

Valence states and solubility limits in ternary iron-tin-antimony mixed oxide catalysts

The electrical conductivity study of a series of ternary Fe–Sn–Sb mixed oxides with 5 at. % Fe has shown that iron dissolves in the structure of SnO₂ as ferric ions and, consequently creates acceptor centers which compensate the doping effect of Sb⁵⁺ ions simultaneously dissolved, thus increasing the maximum dissolution of pentavalent antimony and shifting thereby the apparition limit of Sb³⁺ ions towards higher Sb contents.

---

Fe–Sn–Sb c 5 . %- Fe , SnO₂ , , Sb⁵⁺, . , Sb³⁺ Sb.

     

Deactivation of reforming catalysts. Coke formation on metallic and acidic centers

To check coke formation on metallic (Pt^o) and acidic (Al₃₊) centers of Pt/Al₂O₃ and Pt–Sn/Al₂O₃ catalysts, the application of IR spectroscopy of adsorbed CO for detecting Pt^o–CO (2070 cm^–1) and Al³⁺–CO (2190 cm^–1) bonds has been substantiated. Decrease in the number of active Pt^o and Al³⁺ centers is shown to correlate with that in the dehydrogenation rate of cyclohexane and in the isomerization rate of heptane, respectively.

---

(Pt^o) (Al³⁺) Pt/Al₂O₃ Pt–Sn/Al₂O₃ - CO Pt^o–CO (2070 ^–1) Al³⁺–CO (2190 ^–1). , Pt^o , Al³⁺- .

     

La and Zn promotion of Ru Fischer-Tropsch catalysts

An investigation of the use of La- and Zn-promoters for Ru/SiO₂ F-T catalysts has been carried out. It was found that, while the use of a La-promoter did not result in any improvement over the use of a K one, Zn-promotion resulted in much higher yields of olefins. The CH₄ and olefin selectivities of the Zn-promoted Ru/SiO₂ were essentially insensitive to temperature over the range 250–320 °C. The Zn-promoted catalyst was found to have many of the same catalytic properties previously found for Ru/ZnO, but was much more active. Thus, it is possible to achieve certain interesting catalytic properties for Ru by the use of Zn-promotion without having to make use of the low surface area support ZnO.

---

La Zn- Ru/SiO₂ F-T. , , La- - , Zn- . CH₄ Zn- Ru/SiO₂ , -, 250–320°C. Zn- , Ru/ZnO, . Ru, Zn- ZnO .

     

Double dimethylammonium sulphates of Tb,Dy, Ho,Er, Tm,Yb, Lu and Y

Double sulphates of rare earths with dimethylammonium, with empirical formula (CH₃)₂NH₂Ln(SO₄)₂·4H₂O (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu and Y), were studied by means of thermogravimetry, derivative thermogravimetry and differential thermal analysis from 20 to 700°. Quantitative gravimetric analysis was used for the determination of rare earths and sulphate. The mechanism of thermal decomposition is also suggested.

---

Zusammenfassung Doppelsulfate der seltenen Erden mit Dimethylammoniumionen der empirischen Formel (CH₃)₂NH₂Ln(SO₄)₂·4H₂O (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu und Y) wurden mittels TG, DTG und DTA im Temperaturbereich von 20–700° untersucht. Die Seltenen Erden und Sulfat wurden gravimetrisch bestimmt. Ein Mechanismus der thermischen Zersetzung wird vorgeschlagen.

---

, 20–700° (₃)₂N₂Ln(S₄)₂·4₂, Ln=Tb, Dy, , Er, Tm, Yb, Lu Y. . .

     

Theory of differential thermal analysis taking into account heat exchange between the specimen and reference cells

A basic formula of differential thermal analysis is evolved for the case when the heat transfer coefficient between the specimen cell and the reference cell is not zero. The more general formula obtained differs from the classical formula by including the parameters of the reference cell and the heat transfer coefficient between the cells. It indicates that utilization of the classical formula is not correct if heat exchange occurs between the cells. To utilize the generalized formula, additional measurements of the temperature changes of the reference material are required. However, if the time constants of the two cells are identical, the formula can be changed to assume the form of the classical formula for DTA if a correction factor is introduced which takes into account the effect of heat exchange between the cells.

---

Zusammenfassung Für den Fall, dass der Übertragungskoeffizient zwischen der Proben- und der Referenzzelle nicht Zero ist, wurde eine Grundformel der Differentialthermoanalyse entwickelt. Die entstandene Formel, die vielmehr allgemein ist, weicht von der klassischen dadurch ab, dass sie auch die Parameter der Referenzzelle, und den Wärmeübertragungskoeffizient zwischen den Zellen enthält. Sie deutet darauf hin, dass die Anwendung der klassischen Formel in dem Fall nicht einwandfrei ist, wenn ein Wärmeaustausch zwischen den Zellen zustande kommt. Zur Anwendung der verallgemeinerten Formel sind weitere Messungen des Temperaturaustausches vom Referenzmaterial erforderlich. Sind aber die Zeitkonstanten der zwei Zellen identisch, kann die Formel so geändert werden, dass sie die Gestalt der klassischen DTA-Formel annimt, wenn ein, mit der Wirkung des Wärmeaustausches zwischen den Zellen rechnender Korrektionsfaktor eingeführt wird.

---

, . , , . . , , , , .

     

Systems of supported Pt as catalysts in the isomerization of dimethylcyclohexanes

We report on results obtained for the isomeratization of the different dimethylcyclohexanes over diverse systems of supported Pt. As support systems AIPO₄, SiO₂–AlPO₄ and AlPO₄–Al₂O₃ have been used. The reactions have been carried out in a pulse reactor coupled to a gas chromatograph. The process of isomerization, within the temperature interval studied (393–543 K), requires the presence of hydrogen and of the metallic catalyst, and the results obtained highlight the influence on the selectivity by the temperature, the support used for the deposition of the metal, and the relative stability of the reaction products.

---

, . AlPO₄, SiO₂–AlPO₄ and AlPO₄–Al₂O₃. , . , (393–543 ), . , , , , .