Sodium nitrite and ammonium chloride are the most widely
used thermochemicals
in the oil and gas industry. The kinetics of this reaction when activated
with acids or acid precursors were the subject of extensive research
by several researchers. The activation of such a highly spontaneous/vigorous
reaction by heat is considered a promising reaction control. In this
work, a kinetic study was carried out for the reaction of sodium nitrite
and ammonium chloride salt activated by heat at 1–5 M and temperatures
of 50–90 °C. The study was carried out in both closed
and open systems, with the monitoring of gas evolution and generated
pressure. The study showed a relatively higher order for ammonium
chloride than sodium nitrite. The excess amount of ammonium chloride,
a weak acid, enhanced the reaction as it could be catalyzed by both
heat and acid. The obtained kinetics of the nitrogen generating reaction
is given as d
c
/d
t
= −7.66
× 10
11
C
o
2.45
e
(−91.44 kJ/mol)/
RT
. The reaction kinetics in this study differs from what is
reported in the literature regarding the order of NH
4
Cl,
which was reported to be higher than that of NaNO
2
under
examined conditions. This study has practical significance for controlling
the reactivity of the NH
4
Cl/NaNO
2
nitrogen/heat
generating system and calculating/optimizing nitrogen generation for
a specific field application.