Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

OP-III-1CATALYTIC REACTOR FOR N 2 O ABATEMENT IN ADIPIC ACIDPRODUCTIONChumachenko V.A., Ovchinnikova E.V., Klenov O.P., Noskov A.S.Boreskov Institute of Catalysis SB RAS, pr. Akademika Lavrentieva, 5, Novosibirsk, 630090,Russia; e-mail: vachum@catalysis.ru , ph.: +7 383 3269412Commercial processes currently employed for the production of adipic acid (AA) arebased on oxidation of a mixture of cyclohexanone and cyclohexanol (KA oil) in excess ofstrong nitric acid. Nitric acid is reduced mainly to nitrous oxide, but also to nitrogen, to nitricoxide, and to nitrogen dioxide. Effluents of NO x are recovered as nitric acid or removed in allAA plants. However, N 2 O emission has not been regulated for many years.In 1991 it was pointed out in [1] that N 2 O from AA production is harmful to theenvironment and should be strictly controlled. The only commercial process in use for N 2 Oremoval is non-catalytic incineration of effluents with added fuel under reducing conditions at1200-1500°С, which results in nitrous oxide decomposition to nitrogen and oxygen. Due tothe high worldwide prices for natural gas, this process is rather expensive; specific NGconsumption reaches as much as 500 m 3 per 1 ton of N 2 O.Very limited information is available on catalytic methods for N 2 O decomposition. Ledby DuPont, chemical companies BASF, Asahi, Bayer, ICI and Rhone-Poulenc in cooperationwith catalyst companies are searching for an economical way of N 2 O catalytic removal. Twooptions are usually considered: (1) selective oxidation of nitrous oxide to higher nitrogenoxides followed by its recovering as nitric acid; and (2) decomposing of nitrous oxide tomolecular nitrogen and oxygen. Up to present, no commercial implementation of catalytictechnologies has been reported.The 1997 Kyoto Protocol declared nitrous oxide as one of the main greenhouse gaseswith global warming potential equal to 310. New catalysts and catalytic processes for N 2 Oremoval at moderate temperatures are expected to solve this serious environmental challenge.In this work, a catalytic technology for N 2 O abatement from AA tail-gases is proposed.Typical composition of tail-gases after NО x absorption tower in AA production plant is (invol. %): 11-13 N 2 О; 0.1-0.3 NО x ; 0.06-0.12 СО; 14-15 О 2 ; 3-5 H 2 О; N 2 – balance. Weconsider a two-stage technological system. At the 1 st stage, nitrous oxide is converted tonitrogen and oxygen over BIC proprietary cobalt-zeolite catalyst. At the 2 nd stage nitrogenoxides are selectively reduced by ammonia over commercial vanadium-alumina catalyst.93