Abstract: One disclosed embodiment concerns an aqueous inorganic coating precursor solution comprising a mixture of water, polynuclear aluminum hydroxide cations, and polyatomic ligands selected from nitrate (NO3?), nitrite (NO2?), or combinations thereof. In certain embodiments, the composition has a molar concentration ratio of polyatomic ligands to aluminum of less than 3; an aluminum cation concentration of from about 0.01 M to about 3.5 M; and/or a polyatomic anion concentration of from about 0.1 to about 2.5 times the aluminum cation concentration. Embodiments of a method for forming the precursor solution also are disclosed. For example, certain embodiments comprise adding a metal having a sufficient reduction potential to reduce nitric acid to an aqueous solution comprising aluminum nitrate (Al(NO3)3).

Abstract: By a method and a device for preventing corrosion on and in the region of a gas inlet nozzle during nitric acid condensation, contact of the condensing gas with the nozzle and with the surroundings of the nozzle are supposed to be minimized. This is achieved in that the gas inlet nozzle has a sleeve on the inside in the transition region to the interior of the condenser, by which sleeve a gas inlet orifice in the form of an annular gap is formed, whereby the annular space is provided with at least one feed opening for secondary air, so that an enveloping flow of secondary air is produced around the entering NO gas.

Abstract: A process for producing nitric acid of a concentration in the range of 68 to 76% by weight, using the mono-pressure or the dual-pressure process in which the ammonia feedstock is combusted with the aid of compressed process air. The water vapour content of the process air used for combustion and/or stripping and imported from outside the system, is reduced in this process.

Abstract: A method process to convert inhibited red fuming nitric acid (IRFNA) and/or nitrogen tetraoxide to either dilute or concentrated (98%+) nitric acid. The method describes a process to remove all of the normal inhibitors (if required), that have been reported to been used in IRFNA. The process described will provide nitric acid free of contaminates which are undesirable when using the nitric acid in reactions to produce other products.

Abstract: The present invention describes a process for converting vapor streams from sources containing at least one nitrogen-containing oxidizing agent therein to a liquid fertilizer composition comprising the steps of: a) directing a vapor stream containing at least one nitrogen-containing oxidizing agent to a first contact zone, b) contacting said vapor stream with water to form nitrogen oxide(s) from said at least one nitrogen-containing oxidizing agent, c) directing said acid(s) as a second stream to a second contact zone, d) exposing said second stream to hydrogen peroxide which is present within said second contact zone in a relative amount of at least 0.

Abstract: Nitric oxide is removed from a gas stream by contacting the gas stream with oxygen in the presence of a metal-cation exchanged zeolite, thereby oxidizing the nitric oxide to nitrogen dioxide, then contacting the resulting nitrogen dioxide-containing gas stream with ozone, thereby converting the nitrogen dioxide to nitric acid, nitric acid precursors or mixtures thereof, then contacting the gas stream with an aqueous liquid, thereby scrubbing the nitric acid, nitric acid precursors or mixtures thereof from the gas stream. Contact of the gas stream with oxygen in the presence of a zeolite is carried out at a temperature above the temperature at which significant adsorption of nitrogen dioxide occurs, and the aqueous liquid used as scrubbing agent preferably has a pH greater than 7.

Abstract: The present invention describes a process for converting vapor streams from sources containing at least one nitrogen-containing oxidizing agent therein to a liquid fertilizer composition comprising the steps of:a) directing a vapor stream containing at least one nitrogen-containing oxidizing agent to a first contact zone,b) contacting said vapor stream with water to form nitrogen oxide(s) from said at least one nitrogen-containing oxidizing agent,c) directing said acid(s) as a second stream to a second contact zone,d) exposing said second stream to hydrogen peroxide which is present within said second contact zone in a relative amount of at least 0.

Abstract: A process is described for the removal of nitrogen oxides from waste gases with the recovery of nitric acid or a nitrate solution. The waste gas is reacted with hydrogen peroxide in an amount appropriate to the desired degree of removal of nitrogen oxides, on a catalyst, at a temperature of less than 800.degree. C., preferably in the range of 20.degree. to 100.degree. C., to give the valuable product, nitric acid or a nitrate solution. This may be done in accordance with the invention by bringing the hydrogen peroxide as a solution, i.e., in the liquid phase, into contact with the catalyst through which the waste gas is flowing. The reaction product is either utilized in a gaseous form or processed to nitric acid or a nitrate solution. Alternatively, the hydrogen peroxide may be introduced in a gaseous form, using a honeycombed catalyst, and wherein the hydrogen peroxide is present in at least one half of the stoichiometrically determined amount.

Abstract: A process for oxidizing aqueous elemental phosphorus containing residues (sludges) to produce orthophosphate containing slurries suitable for subsequent reaction with ammonia to produce nitrogen- and phosphorus-containing fertilizer products. It comprises reacting aqueous elemental phosphorus containing residues with certain special mixtures of concentrated nitric acid and sulfuric acid to effect the conversion of the elemental phosphorus content of the residues into mostly orthophosphoric acid and very little orthophosphorous acid with the relative ratios of orthophosphoric acid to orthophosphorous acid produced being dependent upon the weight ratio H.sub.2 SO.sub.4 :HNO.sub.3 employed in the processing. The reaction is conducted at the boiling point of the resulting aqueous reaction medium.

Abstract: The mixture of aqueous nitric and nitrous acids which is produced by the absorption of nitrogen oxides with water in the manufacture of nitric acid is conducted to a closed vessel, where the acid mixture is reacted with oxygen, preferably under pressure, and is then returned to the absorber. This treatment has been found to enhance the absorption of the nitric oxide (NO) component of the gas mixture of NO and NO.sub.2 which is supplied to the absorber in the production of nitric acid. Normally, nitric oxide has a low solubility in the mixture of nitric and nitrous acids. Because nitric oxide oxidation is the controlling factor in the operation of nitric acid plants, this enhanced absorption provides for more efficient and economic nitric acid manufacture, as well as for the reduction of emissions of nitrogen oxides in the acid plant tail gases.The same invention is also applicable to the removal of nitrogen oxides from emissions generated in processes other than nitric acid manufacture.

Abstract: A method for regenerating an aqueous liquid comprising nitrous acid and/or oxides of nitrogen is characterized by feeding the liquid to a column such that the liquid descends through the column. An aqueous solution comprising nitric acid is heated to its boiling point such that the heated nitric acid refluxes into the packed column. An oxygen-containing gas is passed into the liquid, whereby the liquid is converted substantially to nitric acid as it descends in the column.

Abstract: An oxido-reduction process for nitrogen oxides contained in a gas stream also containing oxygen, in a countercurrent gas-liquid contact device. In this process,(a) for values of the ratio NO/NO.sub.2 greater than 1, in that section of the gas-liquid device where the NO.sub.x content in the gas stream is less than about 6000 vpm, the ratio K, which is the ratio of the liquid retention volume in m.sup.3 to the flow rate of the gas stream in Nm.sup.3 /hour, is increased so that the NO.sub.x are preferentially absorbed according to the reaction: NO+NO.sub.2 +H.sub.2 O.fwdarw.2HNO.sub.2 (liquid phase); and(b) oxidation is then induced, to reduce the value of the ratio NO/NO.sub.2 and to restore the conditions of stage (a).In practice, the operating point describes a curve A.sub.0 A.sub.2 B.sub.1 A.sub.3 B.sub.2 A.sub.4, as shown in FIG. 1.

Abstract: The present invention involves a process for removing nitrogen oxides from an off gas stream, such as nitric acid plant tail gas. The off gas is scrubbed with concentrated nitric acid to remove nitrogen oxides to a concentration below about 200 ppm. The nitric acid used in the scrubbing step is subsequently stripped of recovered nitrogen oxides which can be recycled back to a nitric acid plant. The oxidized nitric acid is recovered as concentrated nitric acid which can be used in the initial scrubbing step and/or recovered as product.

Abstract: To remove nitrous gases from gas mixtures there is needed a process and apparatus by which they can be eliminated quickly, without formation of secondary waste and as cheaply as possible. This is done by scrubbing the nitrous gases out of the gaseous mixture with 15-50% nitric acid solution and treating this solution additionally with gaseous oxygen, especially atmospheric oxygen.

Abstract: Intimate and efficient contacting of plural, physically disparate phases, e.g., a gas and a liquid, is achieved by contacting the phases cocurrently in a column. The gas phase is introduced at a velocity between its phase transition inversion point (T) and multiple critical point (M.sub.c) velocities, which velocity is sufficient to create a dispersion of the second phase, i.e., the liquid phase, in the gas and thereby establish at most the following zones, from bottom to top, in the column: a bottom zone of constant liquid concentration designated the emulsion zone, a zone of decreasing liquid concentration, and a zone of constant liquid concentration wherein the liquid exists in the form of droplets. The feed velocity of the liquid is adjusted accordingly to provide a mass liquid concentration value in the emulsion that is between the mass liquid concentration value transition inversion point and multiple critical point values.

Abstract: Gas/liquid reactions are carried out in a downstream reactor in which the gas having a bubble diameter of 0.1 to 4 mm is injected into the liquid flowing downward at an empty tube velocity of 0.14 m/s to 0.5 m/s. The proportion by volume of liquid to gas should be greater than 8:1 and the residence time of the gas at least 6 second per meter of reactor length.

Abstract: Tritium formed in the treatment of spent nuclear fuel and during storage of liquid, radioactive waste products is retained by adding oxygen to said liquid, radioactive waste products, reducing in a subsequent stage the oxygen enriched with tritium and separating it from the tritium. The reduction can be carried out with NO. The higher nitrogen oxides formed can be reacted to nitric acid.

Abstract: The present invention relates to a process for obtaining nitric acid of a concentration higher than the azeotropic concentration by means of the absorption of nitrogen oxides in water or diluted nitric acid and the partial pressure of the nitrogen oxides before absorption is raised partly by compression of the gases that contain the nitrous gases and partly by means of a cycle of diluted nitric acid which is decomposed by the action of the NO contained in the gases, enriching them in NO.sub.2 and which subsequently reform by absorption of NO.sub.2 in water when the partial pressure of the nitrogen oxides is low.

Abstract: DISCLOSED IS A TWO STAGE process AND APPARATUS for preparation of NITRIC AICD characterized by efficient use of heat liberated by the conversion of NITROGEN OXIDES TO NITRIC ACID.

Abstract: Nitric acid having a concentration of at least 98% by weight is obtained from a gaseous stream resulting from catalytic oxidation of ammonia and containing nitrogen oxide and steam, by flowing said stream in an oxidation and condensation column in countercurrent with a stream of nitric acid at 40-60 wt.%, recovering nitrogen peroxide at the top of the column, liquefying said peroxide, bringing it into contact with aqueous nitric acid, oxygen and air in a chemical absorption stage, and distilling the resulting superazeotropic nitric acid. A part of the nitric acid discharged from the oxidation column is directly recycled and the remainder is recycled after distillation to give azeotropic acid and remove water, a part of the latter being used for the chemical absorption.

Abstract: Nitric acid having a concentration of at least 98 wt.% is prepared by recovering in liquid state nitrogen peroxide from a gaseous flow containing the same, by absorption in nitric acid, heating of the resulting solution and liquefaction of the gaseous peroxide evolved, followed by a first chemical absorption of a fraction of the liquid peroxide with nitric acid at 70-80% and air and distillation of the resulting concentrated nitric acid. The gaseous products discharged from said first absorption and comprising unreacted peroxide and air are contacted with nitric acid and water in a second chemical absorption stage, thereby to produce the nitric acid used in the first absorption. The remaining fraction of liquid peroxide is delivered to the distillation column, discharged at the top thereof and recycled to the liquefaction stage, while nitric acid is extracted at the bottom of the distillation column and recycled to the second absorption stage.

Abstract: Nitric acid having a concentration of at least 98 wt.% is produced from nitrogen peroxide by absorbing the latter in superazeotropic nitric acid, distilling the resulting solution so as to recover nitric acid at a concentration of at least 98 wt.% and nitrogen peroxide, liquefying the latter and reacting it in a first stage with aqueous nitric acid (70-80% wt.%) and air and delivering the resulting superazeotropic nitric acid, together with the solution, to the distillation column. Nitrogen peroxide and oxygen unreacted in the first stage are contacted with nitric acid at 68-75 wt.% in a second stage, thus to produce said aqueous nitric acid fed to the second stage. The said nitric acid at 68-75 wt.% and the superazeotropic acid used for the absorption are extracted from the bottom part of the distillation column.

Abstract: A process for reducing the level of nitrogen oxide contaminants in an industrial effluent gas comprises (a) oxidizing said gas to convert the contaminants substantially to a mixture of N.sub.2 O.sub.3 and NO.sub.2 and (b) passing the oxidized gas through an aqueous medium containing an amount of hydrogen peroxide maintained at a level just sufficient to oxidize the N.sub.2 O.sub.3 and NO.sub.2 to HNO.sub.3.

Abstract: A method for conducting a chemical reaction in acidic, basic, or neutral solution as required and then regenerating the acid, base, or salt by means of ion exchange in a closed cycle reaction sequence which comprises contacting the spent acid, base, or salt with an ion exchanger, preferably a synthetic organic ion-exchange resin, so selected that the counter ions thereof are ions also produced as a by-product in the closed reaction cycle, and then regenerating the spent ion exchanger by contact with the by-product counter ions. The method is particularly applicable to closed cycle processes for the thermochemical production of hydrogen.