Formation of NOx precursors during the pyrolysis of coal and biomass. Part VI. Effects of gas atmosphere on the formation of NH3 and HCN

Liping Chang, Zongli Xie, Ke Chang Xie, Kerry C. Pratt, Jun Ichiro Hayashi, Tadatoshi Chiba, Chun Zhu Li

Research output: Contribution to journalArticle

72 Citations (Scopus)

Abstract

Our results indicate that the gas atmosphere surrounding coal/char particles can greatly affect the formation of NH3 and HCN through its influence on the availability of H radicals. Based on our results, it is believed that the chemisorption of CO2 on the nascent char surface can consume H radicals or block the access of N-sites by H radicals for the formation of NH3 and HCN. For the chars whose thermal cracking generates little H radicals, the gasification of char by CO2 can also generate additional H radicals, enhancing the formation of NH3. However, even gasification of char in CO2 at 950 °C does not lead to the formation of HCN. The oxidation of coal with 4% O2 at low temperatures (400-600 °C) leads to the formation of HCN as well as NH3 due to the enhanced formation of (H) radicals. The gasification of coal with 15% H2O drastically enhances the formation of NH3 due to the greatly enhanced availability of H as an intermediate between the reactions of H2O and char. These results support our reaction mechanisms proposed previously, emphasising the importance of H on the formation of NH3 and HCN during pyrolysis, which can also be extended to the conversion of coal-N during gasification.

Original languageEnglish
Pages (from-to)1159-1166
Number of pages8
JournalFuel
Volume82
Issue number10
DOIs
Publication statusPublished - Jul 1 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry

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