Über die katalytische Oxidation von Ammoniak bei der industriellen Salpetersäure‐Herstellung

Holzmann, H.

doi:10.1002/cite.330390206

“…This phenomenon can have manifold causes, including interaction with impurities that can result in the creation of some volatile constituents, or some substances which make the catalyst surface mechanically weak. The formation of noble metal oxides that occurs during the usual forming process follows the same trend (Falbe and Hasserodt 1978;Holzmann 1967Holzmann , 1968McCabe et al 1974McCabe et al , 1986 and are intensified by the difficult working conditions. Most of the above-mentioned undesirable changes in the catalyst surface occur frequently and increase in severity during the operating period, finally leading to deactivation (Zabrzeski 1987).…”

Section: Introductionmentioning

confidence: 71%

Investigation of unusual inactivity of industrial platinum‐rhodium catalyst gauze

Lomic

¹

,

Kis

²

,

Grabovac

³

et al. 2002

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Summary:The aim of this work was to obtain information about the causes of unusual lack of activation of fresh, unused, 90% platinum-10% rhodium catalyst gauze that was detected after the activation process in an industrial ammonia oxidation plant. To reach the usual efficiency, it was necessary to regenerate the catalyst immediately after the activation procedure by using an acid bath. To avoid future unexpected shutdowns in the ammonia oxidation plant, the possible sources of impurities accumulated on the catalyst surface were investigated by an analysis of the experimental results and technological processes. The absence of accumulation on the unused catalyst surface eliminates the possibility of contamination during the preparation, while the composition of the impurities indicates that it cannot result from the reactor construction material. In mixed feedstock, detectable amounts of the poisons mentioned were not detected either after filtration or before the reactor. All these considerations imply that the time when the catalyst contamination occurred must have been before the contact with the gas mixture. From data obtained, it is hypothesized that the origin of this substance is from the polluted air in the industrial area where the ammonia oxidation plant is located and that the accumulation probably took place during the preparation of the catalyst pad.

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Nitric Acid

Clarke¹,

Mazzafro²

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Nitric acid is a strong acid, a powerful oxidizing compound, and a nitrating agent. These properties make it an important basic chemical compound that is used in the production of many important chemicals such as fertilizers, polyurethanes, organic chemical intermediates, pharmaceuticals, synthetic fibers, dyes, insecticides, fungicides, and explosives. Nitric acid is produced through the oxidation of ammonia to nitrogen oxides, which are then absorbed by water to produce nitric acid. Weak nitric acid processes produce nitric acid in the concentration range of 50–65 wt %. The two main types of weak acid process are the monopressure process and the dual‐pressure process. The monopressure process operates at either moderate (0.3–0.6 MPa) or high pressure (0.7–1.2 MPa). The dual‐pressure process performs the conversion of ammonia at atmospheric or moderate pressures (0.3–0.6 MPa) and the absorption of nitrogen oxides at high pressure (1.1–1.5 MPa). Nitrogen oxides in the tail gas leaving the process are reduced to below environmental regulatory limits by either extended absorption or catalytic abatement. Strong nitric acid of 98–99 wt % is produced by either extractive distillation or direct strong nitric acid process. The extractive distillation process uses either magnesium nitrate or sulfuric acid as a dehydrating agent to surpass the maximum boiling azeotrope of nitric acid. The direct strong nitric acid process is similar to the weak nitric acid process, but has additional processing steps that bypass the azeotrope to produce strong nitric acid. Information on the chemical and physical properties, manufacturing processes, materials of construction, uses, safety and health, analytical methods, and process licensors of nitric acid is included.

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Nitric Acid

Clarke¹,

Mazzafro²,

Staff³

2005

Kirk-Othmer Encyclopedia of Chemical Technology

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Nitric acid is a strong acid, a powerful oxidizing compound, and a nitrating agent. These properties make it an important basic chemical compound that is used in the production of many important chemicals such as fertilizers, polyurethanes, organic chemical intermediates, pharmaceuticals, synthetic fibers, dyes, insecticides, fungicides, and explosives. Nitric acid is produced through the oxidation of ammonia to nitrogen oxides, which are then absorbed by water to produce nitric acid. Weak nitric acid processes produce nitric acid in the concentration range of 50–65 wt %. The two main types of weak acid process are the monopressure process and the dual‐pressure process. The monopressure process operates at either moderate (0.3–0.6 MPa) or high pressure (0.7–1.2 MPa). The dual‐pressure process performs the conversion of ammonia at atmospheric or moderate pressures (0.3–0.6 MPa) and the absorption of nitrogen oxides at high pressure (1.1–1.5 MPa). Nitrogen oxides in the tail gas leaving the process are reduced to below environmental regulatory limits by either extended absorption or catalytic abatement. Strong nitric acid of 98–99 wt % is produced by either extractive distillation or direct strong nitric acid process. The extractive distillation process uses either magnesium nitrate or sulfuric acid as a dehydrating agent to surpass the maximum boiling azeotrope of nitric acid. The direct strong nitric acid process is similar to the weak nitric acid process, but has additional processing steps that bypass the azeotrope to produce strong nitric acid. Information on the chemical and physical properties, manufacturing processes, materials of construction, uses, safety and health, analytical methods, and producers of nitric acid is included.

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Über die katalytische Oxidation von Ammoniak bei der industriellen Salpetersäure‐Herstellung

Cited by 11 publications

References 10 publications

Investigation of unusual inactivity of industrial platinum‐rhodium catalyst gauze

Investigation of unusual inactivity of industrial platinum‐rhodium catalyst gauze

Nitric Acid

Nitric Acid

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