Free-radical model for coal conversions. Effect of conversion level and concentration on thermolysis of bibenzyl

✍ Scribed by Marvin L. Poutsma

• Publisher: Elsevier Science
• Year: 1980
• Tongue: English
• Weight: 490 KB
• Volume: 59
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(80)90219-7

✦ Synopsis

The product distributions from thermolysis of bibenzyl at 366°C and 400°C have been determined as a function of conversion level and of bibenzyl concentration from the dilute gas to the neat liquid. At very low (l-3%) conversion levels, five primary products have been detected: toluene (21, stilbene (3). 1,2,3triphenylpropane (41, 1,2,3,4_tetraphenylbutane (51, and l,l-diphenylethane (6). Increasing the concentration of bibenzyl decreases the ratio 4:5 and increases the amount of rearrangement to 6. This product behaviour is interpreted by a multistep, nonchain, free-radical network involving initial formation of benzyl radicals by homolysis of bibenzyl, formation of 1,2-diphenylethyl radicals by hydrogen atom transfer, and subsequent coupling, disproportionation, and rearrangement of the radicals. At higher conversion levels, the primary product distribution is markedly perturbed because products 4 and 5 are inherently less stable than bibenzyl; additional, secondary products include diphenylmethane and phenanthrene.

* At much higher temperatures (=7OO"C) in the vapour phase, benzene and styrene have been observedt6, presumably derived from p-scission of radical 8