A study on NO reduction by biomass tar-using phenol as a model compound of tar from updraft biomass gasification



The character of biomass tar to reduce nitric oxide (NO) under conditions relevant for the reburning process is investigated experimentally. Flow reactor experiments on reduction of NO by phenol, a model compound of tar from updraft biomass gasification, are conducted from fuel lean to rich conditions, covering temperatures of 1173–1573 K and equivalence ratio of 0.34–1.73. Under the oxygen rich conditions, with the temperature increased, the efficiency of NO reduction was first increased which may be caused by the increasing quantity of hydrocarbon and non-hydrocarbon radicals produced by cracking of phenol. With a further increase in temperature, the thermal crack of phenol was enhanced and less oxygen is needed. The crack products were consumed mostly through reacting with the rich oxygen, and inhibit the NO reduction reactions. Under the fuel rich conditions, the efficiency of NO reduction increased continuously with the temperature because the increased temperature promotes phenol decomposition as well as the reactions of NO reduction by the crack products. NO reduction efficiency decline with the decrease of phenol concentration. The different cracking and polymerization action by phenol and benzene presented the different NO reduction characters of tar. And comparing with other fuels shed light on the effect of tar on NO reduction. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 47–53, 2015