Mechanisms of molecular product and persistent radical formation from the pyrolysis of hydroquinone

作者：Truong Hieu; Loranicki Slawo; Dellinger Barry^*

来源：Chemosphere, 2008, 71(1): 107-113.

DOI：10.1016/j.chemosphere.2007.10.007

• biomass combustion
• hydroquinone
• semiquinone
• combustion by-products
• cyclopentadiene
• phenoxyl radical

Hydroquinone is considered to be one of the major, potential molecular precursors for semiquinone-type radicals in the combustion of complex polymeric and oligomeric structures contained in biomass materials. Comprehensive product yield determinations from the high-temperature, gas-phase pyrolysis of hydroquinone in two operational modes (rich and lean hydrogen conditions) are reported at a reaction time of 2.0 s over a temperature range of 250-1000 degrees C. Below 500 degrees C, p-benzoquinone is the dominant product, while at temperatures above 650 degrees C other products including phenol, benzene, styrene, indene, naphthalene, biphenylene, phenylethyne, dibenzofuran and dibenzo-p-dioxin are formed. Hydrogen-rich conditions initially inhibit hydroquinone decomposition (below 500 degrees C) but promote product formation at higher temperatures. The decomposition process apparently proceeds via formation of a resonance stabilized p-semiquinone radical. Detailed mechanisms of formation of stable molecular species as well as stable radicals are proposed.

• 出版日期2008-3