Role of CO2 and H2O on NO Formation during Biomass Char Oxidation

Oskar Karlström,Daniel Schmid,Mikko Hupa,Anders Brink

doi:10.1021/acs.energyfuels.0c03471

Oskar Karlström, Daniel Schmid + Show 2 more

Open Access

https://doi.org/10.1021/acs.energyfuels.0c03471

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Abstract

We have investigated how CO2 and H2O influence NO release rates during char oxidation of biomass. In addition, the role of catalytic elements in these processes has been studied. NO release rates w...

Highlights

Combustion and gasification of biomass generate NOx emissions
Vol N is released as NH3, HCN, HNCO, NO, N2O, N2, and tar N.8−10 The N species distribution depends upon a range of factors, such as the nitrogen content of the fuel, volatile matter, heating rate, final temperature, surrounding gas atmosphere, metals with catalytic effects, such as Ca and Mg, and how nitrogen is bound to the biomass
Some N2O is formed during the char oxidation stage, but reported concentrations of N2O from biomass char combustion experiments are typically low compared to concentrations of NO, with some exceptions

Summary

INTRODUCTION

Combustion and gasification of biomass generate NOx emissions. For bound nitrogen biomass, (fuel-N).[1] most NOx originates from fuelCertain biomasses, such as pine or birch wood, have low nitrogen contents, while, for example, algae or annual crops may have high nitrogen contents.[2]. Vol N is released as NH3, HCN, HNCO, NO, N2O, N2, and tar N.8−10 The N species distribution depends upon a range of factors, such as the nitrogen content of the fuel, volatile matter, heating rate, final temperature, surrounding gas atmosphere, metals with catalytic effects, such as Ca and Mg, and how nitrogen is bound to the biomass. 7 0 10 0 further to NH3.20 Recently, it was suggested on the basis of density functional theory computations that NO is a primary reaction product in the reaction between char-N and CO2.21 For spruce bark, it has been shown that H2O reacts with charN, forming NH3.22 In many industrial combustion and gasification systems, CO2 and H2O concentrations can be adjusted, for example, via flue gas recirculation. To clarify how the ash-forming elements influence the NO formation chemistry, the biomasses were demineralized and the NO release rate experiments were repeated

EXPERIMENTAL SECTION

RESULTS AND DISCUSSION

CONCLUSION

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