New aspects of the mechanism for the thermal hydrocracking of indan and tetralin

Abstract

Thermal cracking of indan and tetralin in the gas phase was carried out in a flow reactor at 500°C and 8 MPa pressure in the presence of hydrogen and nitrogen. The primary reactions are ring cracking and dehydrogenation, regardless of the nature of the second component. Ring cracking, however, is strongly enhanced by the presence of hydrogen. This enhancement becomes less significant with increasing concentration of the hydrocarbon in the gaseous reaction mixture and also with a decreasing ratio of hydrogen to hydrocarbon. At hydrocarbon concentrations larger than approximately 0.5 g.mol/L and Hz-to-HC molar ratios of 1 or lower, conversion rates are almost equal in hydrogen and in nitrogen. Ring cracking exhibits different kinetic behavior in nitrogen than in excess of hydrogen. This illustrates the occurrence of two complementary cracking mechanisms, each of which can dominate in certain concentration ranges. The Hz-initiated ring cracking is gradually transformed into a hydrogen-donor mechanism as the leading reaction scheme when the concentration of indan or tetralin is increased.

Thermolysis of 1,3,8-Nonatriyne: Evidence for Intramolecular [2 + 4] Cycloaromatization to a Benzyne Intermediate

“…At 650 °C, the product ratio was 60:40, which suggests that indene is predominantly a secondary product of indan dehydrogenation. This has literature precedent and was confirmed by pyrolysis of indan under the same conditions.

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Thermal Decomposition of Jet Fuel Model Compounds under Near-Critical and Supercritical Conditions. 2. Decalin and Tetralin

“…Reaction Mechanisms for the Thermal Decomposition of Tetralin. The product distributions obtained from the thermal decomposition of Tetralin can be rationalized by the reactions shown in Scheme . ,,, The source of initiating radicals is not clear and the trace impurities present in original Tetralin may be crucial . Penninger 13 proposed that the initiation can occur by a reactor-wall-catalyzed cleavage of the α carbon−hydrogen bond to form a 1-tetralyl radical and a hydrogen atom.…”

“…It should be mentioned that under high-pressure supercritical conditions, the interconversion between the 1-tetralyl radical and the 2-tetralyl radical (eq 24) could also occur . The formation of n -butylbenzene can be explained by the hydrogen atom addition to Tetralin, followed by decomposition and subsequent hydrogen abstraction (eq 25). , …”

“…The ring-opening and -cracking reactions are always less important at temperatures below 850 °C. It should be mentioned that the ring-opening reactions are markedly accelerated in the presence of hydrogen. , …”

Tritium as a tracer in coal liquefaction. 1. Hydrogen mobility of Tetralin under coal liquefaction conditions

“…In such processes, it is important to study the thermal behavior of tetralin. Recently, much attention has been focused on the mechanism of thermolysis of tetralin in the absence and presence of coal (Cronauer et al, 1978(Cronauer et al, ,1979Hooper et al, 1979;Benjamin et al, 1979;Franz and Camaioni, 1980a,b;Penninger, 1982;McPherson et al, 1985;Vlieger et al, 1984; Poutsma et al, 1982; Yen et al, 1976 and references cited therein). For example, Hooper et al re-ported that tetralin did not disproportionate to naphthalene and decalin between 300 and 450 °C (Hooper et al, 1979).…”