chemical physics of discharges - Argonne National Laboratory

Hydrazine Synthesis in A Silent dlectrical
Dischame.
Thornton J.D., Charlton W.D., SPeddina; P.L.
Department of Chemical bngineering, ,
University of Newcastle-upon-Tyne, Merz
Court, Claremont Road, Newcastle-upon-
Tyne 2. dngland.
IIU!HODlr CT ION.
The eynthesis of hydrazine from ammonia ursing the
eilent electric discharge was firet demonstrated by Beeson
in 1911 (1). Subsequent investigation ehowed that both
the electrical energy yield and percentage conversion
obtained were very low (2,3) and interest in trie procese
waned. Further work was introduced in the early 1950's
enabling substantial improveuents in yields to be obtained
in certain circumstaxcea and a better understanding of the
kinetic mechanisms in the discnarge to emera. Devine and
Burton (4) showed that significant hydrazine fornation only
took place in the positive column of a D.C. discharge. \
Moreover, they found that yields could be substantially
increased if tne atomic hydrogen concentration in the dis-
charge could be reduced by recombination. These general
observations were later confirmed b: Hathsack (5). As a
reeult mechanisms were proposed for hydrazine syntheeie baaed
I on the underlying premise that the hydrazine was fket
formed in the discharge and then degraded by back reactions.
kchi (6) enowed that yielde could be increased by reducing
the residence time of the hydrazine in the diechargo in
agreement with the general premise of hydr85ine dyradation
in the discharge. Subeequent work nas not been at variance
with thie finding (7,83.
Recently, I.C.I. of the U.K. have reported (9) that
removal of product hydrazine in a liquid absorbent give0 a
subetantial increase in yield and an improvement In p ep
centage conversion. Thia ie, of cour~e, a modification of
the general premise of hydrazine degraation in the diecharge
proposed by Devine and Burton (4) and Oucbi (6). Furthermore,
following on the pioneering work of Ouchi (61, and other.
(lo), I.C.I. apparently were able to achieve even better
yields by euitable modification of the waveform characterietice
of the discharge. In order to confirm their clair
and to help clarify the mechanisms taking place in the diecharge,
work wae commenced on this eyetem at the Univereity
of Newcastle-upon-Tyne in 1965. Thie ie a prelimiPary
statement of the reaulte obtained to date.
BXPrnIrt&rn&.
The main ah of thie work was to attempt to hCI=eaEe
hydrazine yielde by reducing the residence tine of the
product in the discharge. A concentric barrier dimcharge
reactor was employed with and without trie uee of a liquid
abeorbent. Reactant flow rate wae increaeed UP to the