Interactions of NiO particles with polycyclic aromatic hydrocarbons and acetylene generated from the pyrolysis of a model fuel

Experiments have been conducted to study the effects of NiO, a prevalent form of nickel in combustion-generated ash particles, on polycyclic aromatic hydrocarbons (PAH) and other hydrocarbons in it fuel product mixture. The fuel product mixture is generated from the gas-phase pyrolysis, in N-2, of the model fuel catechol in a quartz tube reactor at 1100 K and 5 s, a condition that ensures full conversion of the catechol and produces a mixture-of PAH, hydrocarbon gases, and oxygen-containing species-that is representative of the products of practical liquid and solid fuels in pyrolysis and fuel-rich combustion environments. Once formed, the product mixture is passed, at the same temperature, through a bed of ultrafine NiO particles held in-place by quartz wool, in the contact zone of the reactor, The products exiting the reactor are-quenched collected and analyzed by non-dispersive infrared analyzers, gas chromatography, and high-pressure liquid chromatography with diode-array ultraviolet-visible absorbance detection. The results from the experiments at 1100 K show that compared to the case of no inorganics in the contact zone-when NiO is present: PAH-yields are reduced 86% (from 10.8% to 1.48% fed carbon); all of the highly mutagenic 5- and 6-ring PAH are eliminated; and all of the acetylene, the highest-yield hydrocarbon product when NiO is absent, and other hydrocarbons with carbon-carbon triple bonds are eliminated from the gas phase phase. Most of the surface-bound carbon is released: as CO Similar experiments at 1275 K show that-except for the release of the surface-bound carbon as CO-the selective surface effects of NiO bring about similar results at higher temperature: 89% reduction in PAH yield, elimination Of mutagenic 5- and 6-ring PAH, removal of acetylene and acetylenic species, as well as a decrease in the production of solid carbon (not formed at 1100 K). (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.