Cinética da redução de NOx pelo ácido amino sulfâmico : modelagem e desenvolvimento

Abstract

Elevated levels of nitrogen oxides (NOX) from flue gases have recently become a major issue in industrial environment. This causes that the laws are becoming each time more demanding. The most employed reduction processes are: absorption by an aqueous acidic solution and catalytic gas-solid reduction. The nitrogen oxides absorbed into water leads to the formation of nitrous and nitric acid. The nitrous acid is unstable and hydrolyses into nitric acid and nitrogen monoxide which is more pollutant then than nitrogen oxides (NOX). But it may be absorbed by a sulfamic acid solution in a mechanically stirred closed reactor, where the products of this reaction are sulfuric acid and N2 which can then be directly released into the atmosphere. The present study performed the reduction of nitrous acid (0.00143 to 0.00333 kmolm-3) by an amimo sulfamic acid solution (0.00143 to 0.00500 kmolm-3). First the favorable operational conditions were analyzed (stoiquiometric ratio, agitator speed and temperature). From the results the apparent kinetic constant was obtained ( K = 0.00385 kmol.m-3.s-1) e the gasliquid mass transfer coefficients (kLa = 0.00508 s-1; 0.00738 s-1; 0.01272 s-1; 0.03093 s-1; 0.04706 s-1; 0.05272 s-1) varied with the respective agitation speed (200rpm; 300rpm; 400rpm; 600rpm; 700rpm), where the operational conditions were T = 301 K, M = 2.5 and pH = 2.0