Nitric Acid → Nitric Acid

Participants

Reaction Steps

In carrying out the process of the invention, an aqueous nitric acid solution containing about 1/11 to about 1/1.3 and preferably about 1/6 to about 1/2 by weight nitric acid is introduced into reactor 2 through line 10. The nitric acid solution is evenly distributed across the top of the reactor to establish a uniform flow of nitric acid downwardly through column 2. At the same time, gaseous sulfur dioxide is introduced into the bottom of column 2 through line 12. The sulfur dioxide flows through a gas distributor (not shown) positioned in the bottom of column 2, to establish an even flow of sulfur dioxide upwardly through column 2. The nitric acid and sulfur dioxide enter column 2 at a nitric acid to sulfur dioxide molar ratio of at least 0.7 to 1, and these reactants preferably enter at a molar ratio of at least 1 to 1. As the reactants pass through column 2 they come into intimate contact and react to produce nitric oxide product gas. Because the ratio of nitric acid to sulfur dioxide everywhere in column 2 is significantly greater than the stoichiometric ratio, very little or no nitric acid is reduced to nitrous oxide or nitrogen. Furthermore, the ratio of water to sulfur dioxide entering column 2 is sufficient to minimize nitrogen dioxide formation during the reaction stage of the process. Sulfuric acid waste, together with excess nitric acid and water leave column 2 via line 16 and are sent downstream to a spent acid treatment facility (not shown).

Provenance & Evidence