A. V. Topchiev

Transformations of cycloalkenes over aluminum silicates

1. A study was made of the catalytic transformations of cyclohexene over aluminum silicates. 2. At 300–350° at atmospheric pressure, about 60% of the cyclohexene is isomerized into methylcyclopentenes, which are then partially hydrogenated to methylcyclopentane. About 40% of the cyclohexene is dimerized, and the dimer is isomerized into hydrocarbons of the decalin and octalin series; subsequent isomerization, hydrogenolysis, and dehydrogenation of these lead to the formation of tetraalkylbenzenes and dialkylnaphthalenes as end products. 3. On the basis of the study of the transformations of cyclohexene it is suggested that in the processing of petroleum products over aluminum silicates, together with other aromatization reactions, the transformations of unsaturated cyclic compounds play an important part. 4. Of the hydrogen consumed in the course of the transformations of cyclohexene, 50–55% is accounted for by the polymeric compounds transformed in the process into aromatic and naphthalene hydrocarbons, and 45% is accounted for by coke-forming condensation products.

Chromium oxide catalysts for the polymerization of ethylene

1. The activity of the catalyst depends on the relative amounts of CrVI and CrIII and on the extent of the dehydration of the aluminum silicate. The deactivation of the catalyst is due to the more complete removal of active oxygen occurring either at too high a temperature or when the supply of air is inadequate. 2. In the course of the thermal treatment of the catalyst aluminum oxide enters into chemical reaction with CrO3, and this retards the reduction of CrVI to Cr111. No interaction is observed between silicon oxide and CrO3. 3. The activation of the catalyst at high temperatures is necessary only for the dehydration of the aluminum silicate, as the maximum amount of CrVI is present before the heating and the interaction between Cr compounds and alumina starts at low temperatures (103–108°). 4. The chromium catalyst investigated has high sorptive power and is readily reduced to Cr111 under the action of high temperature and hydrocarbons. 5. Spent catalysts can be regenerated.

Synthesis of alkylindans

1. Reaction between indan and olefins, namely propene and 1-butene, in presence of anhydrous aluminum chloride proceeds with formation of high yields of the corresponding monoand di-alkylmdans substituted in the aromatic nucleus. Under the same conditions isopropylindan and propene give triisopropylindan. 2. Reaction between indan and 2-methyl-2-butene under the same conditions proceeds with much greater difficulty. The yield of the alkylindan is much lower. Higher alkylation products are not formed. Reaction between these hydrocarbons in presence of BF3.H3PO4 as catalyst proceeds analogously. 3. Isopropyl-, diisopropyl-, triisopropyl, sec-butyl-, di-sec-butyl-, and amyl-indans, each having their substituents in the aromatic nucleus, were prepared. With the exception of isopropylindan, all these hydrocarbons were prepared for the first time.

Some organosilicon compounds containing siloxane-carbon, silthiane-carbon, and silazane- carbon groupings in the chain

Some organosilicon compounds containing siloxane-carbon, silthiane-carbon, and silazane-carbon groupings in their main chains were synthesized, and their physical and chemical properties were determined.

Demethylation and isomerization of pseudocumene on aluminosilcates

1. The dealkylation of pseudocumene accompanied by the conjugated alkylation of benzene and toluene was investigated at different temperatures and pressures in the presence of aluminosilicates. 2. Application of pressures in the range of 5–10 atm at temperatures of 450–480° expedited the reactions mentioned above. As a result of a single treatment of a mixture of pseudocumene with toluene, a yield of xylenes comprising approximately 30% of the catalyzate was obtained. 3. In the absence of benzene and toluene, pseudocumene was subjected to dismutation with the formation of a mixture of isomeric xylenes and tetramethylbenzenes. 4. Application of vacuum suppressed to a considerable extent the transfer of methyl groups and had the effect of channeling the reaction in the direction of the isomerization of pseudocumene.

Preparation of polypropylene over a chromium oxide catalyst

The yield of highly crystalline polypropylene was considerably increased by polymerization of propylene on a chromium oxide catalyst in the presence of small amounts of i-(C4H9)3Al.

Polymerization of ethylene over a chromium oxide catalyst at at mospheric pressure in absence of solvent

Polyethylene was prepared by the gas-phase polymerization of ethylene over a chromium oxide catalyst at ordinary pressure in absence of solvent at 110–180°.

Catalytic transformations of individual naphthene hydrocarbons and cyclohexene in presence of benzene

1. An investigation was made of the transformations of some individual naphthene hydrocarbons and of cyclohexene in presence of benzene over synthetic aluminum silicates. 2. At 525–530° and 10–15 atm, the transformations of these cyclic hydrocarbons in presence of benzene are directed mainly toward the formation of aromatic hydrocarbons of low molecular weight: toluene, xylenes, and others. The presence of benzene has a favorable effect on the aromatization of cyclohexanes and cyclohexene. 3. In the catalytic treatment of naphthenes, aromatization is accompanied, to some extent, by the destructive alkylation of benzene and by the cracking and isomerization of the original cycloalkanes.

Catalytic transformations of individual paraffins and olefins in the presence of benzene over synthetic aluminum silicates

1. An investigation was made of the catalytic transformations of heptane, 2,2,4-trimethylpentane, hexadecane, octene, and a mixture of amylenes in presence of benzene over synthetic aluminum silicates. 2. At 500–525° and 15 atm the catalytic transformations of these aliphatic hydrocarbons in presence of benzene are directed mainly toward the formation of toluene, xylenes, and other alkylbenzenes of low molecular weight. 3. The presence of benzene in the mixture favors the aromatization of the original hydrocarbons, Other reactions which occur to some extent are destructive alkylation of benzene, isomerization, hydrocracking, and autodestructive alkylation of aliphatic hydrocarbons and their decomposition products.

Preparation of aromatic hydrocarbons by the catalytic treatment of the products of the coking of coal and of the pyrolysis and thermal cracking of petroleum

1. An investigation was made of the catalytic aromatization of thermal-cracking distillates and the dealkylation of the hydrocarbons of coal-tar distillate in presence of toluene and of the crude toluene fraction of light pyrolysis oil. 2. Under optimum conditions the use of somewhat elevated pressure (3–15 atm) accelerates the reactions of aromatization, dealkylation, and alkylation of the original hydrocarbons and directs the process toward the maximum formation of xylenes. Depending on the composition of the raw material, the yield of xylene fraction on the amount of material consumed in one passage varies in the range 37.5–38%, that of benzene in the range 14–27.2%, that of light gasoline in the range 2.2–8.5%, and that of the alkylbenzene fraction of b.p. 149–180° in the range 14.4–20.6%. 3. The presence of toluene in the mixture favors the aromatization of the hydrocarbons of cracking distillate with appreciable suppression of coke- and gas-formation processes. In the formation of xylenes, in addition to the aromatization of the original hydrocarbons, the dealkylation of polyalkylbenzenes and the conjugated alkylation of toluene are of great importance. The xylene fractions of the catalyzates consist mainly of a mixture of the three isomeric xylenes and are notable for their low contents of ethylbenzene.