Open AccessStable isotope fractionation of nitrous oxide during thermal decomposition and reduction processes
Author(s) -
Ogawa Mitsuteru,
Yoshida Naohiro
Publication year - 2004
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jd004652
Subject(s) - nitrous oxide , isotopomers , chemistry , thermal decomposition , decomposition , analytical chemistry (journal) , oxide , inorganic chemistry , organic chemistry , molecule
Kinetic isotope effects in nitrous oxide thermal decomposition and reduction reactions were investigated in flowing N 2 O/He and N 2 O/He/H 2 systems. The intramolecular distribution of stable isotopes, isotopomer, was measured and evaluated using an isotope ratio mass spectrometer equipped with a modified collector system. Thermal decomposition and reduction of nitrous oxide were carried out using a flow tube reactor made of quartz glass in the temperature range of 1173–1373 K. Both thermal decomposition and hydrogen reduction of nitrous oxide proceeded by first‐order kinetics. Isotopomer ratios (δ 15 N bulk , δ 15 N α , δ 15 N β , and δ 18 O) of residual nitrous oxide were found to follow a Rayleigh model based on batch distillation. Residual nitrous oxide was depleted slightly in 15 N during thermal decomposition but slightly enriched in 15 N during hydrogen reduction. Regarding the nitrogen isotopomers, results showed that the central nitrogen atom, N α , was enriched in 15 N during both destruction reactions of nitrous oxide. Although the N 2 O destruction reactions proceeded at high temperature, large isotopic fractionations of nitrogen isotopomers were observed. Enrichment factors for nitrous oxide as a result of thermal decomposition and reduction reactions were evaluated.