Ammonium nitrite prodn. by absorption under pressure - using aq. basic ammonium cpd. soln. and gas contg. nitric oxide, nitrogen di:oxide and oxygen

摘要

prodn. by absorption of a gas contg. NO, NO2, O2 and min. 65 vol.% inert gas in an aq. absorption soln. contg. a basic NH4 cpd. (I), using a gas with a NO:NO2 molar ratio of min. 0.10, pref. min. 0.60, w.r.t. (I), is carried out at a pressure of 0.14-1.76, pref. 0.35-1.41 at.g. (2-25, pref. 5-20 psig.). NH4NO2 is used (in aq. soln.) in the mfr. of hydroxylamine cpds., which are in large amts. for the prodn. of caprolactam via cyclohexanone-oxime. Operation within the stated pressure range allows the prodn. of high yields and greatly reduces NOx losses in the waste gas. In an example, absorption of a gas contg. 8.25% NO, 0.92% NO2 and 5.96% O2 in an aq. soln. contg. 5.5% NH4HCO3 and 16.4% (NH4)2CO3 was carried out at (a) atmos. pressure, (b) 0.70 at.g. In (b), pt. of the gas was pre-oxidised, to increase the NO2 content in the final stage. The NOx content of the waste gas was (a) 1.2, (b) 0.06 vol.%.