Concentration sulfuric acid

In the batch methylene chloride process, the sulfuric acid concentration can be as low as 1% and only limited desulfonation is required to reach a combined acetic acid content of 62.0%. With perchloric acid catalyst, the nearly theoretical value of 62.5% combined acetic acid is obtained. 

The Mn ion is so unstable that it scarcely exists in aqueous solution. In acidic aqueous solution, manganic compounds readily disproportionate to form Mn ions and hydrated manganese(IV) oxide, Mn02 2H20 in basic solution these compounds hydroly2e to hydrous manganese(III) oxide, MnO(OH). Sulfuric acid concentrations of about 400 450 g/L are required to stabilize the noncomplexed Mn ion in aqueous solutions. 

The principal reactions are reversible and a mixture of products and reactants is found in the cmde sulfate. High propylene pressure, high sulfuric acid concentration, and low temperature shift the reaction toward diisopropyl sulfate. However, the reaction rate slows as products are formed, and practical reactors operate by using excess sulfuric acid. As the water content in the sulfuric acid feed is increased, more of the hydrolysis reaction (Step 2) occurs in the main reactor. At water concentrations near 20%, diisopropyl sulfate is not found in the reaction mixture. However, efforts to separate the isopropyl alcohol from the sulfuric acid suggest that it may be partially present in an ionic form (56,57). 

In Germany and France the Baumii scale is calculated using 144.3 as the constant. The Baumii scale only includes the sulfuric acid concentration range of 0—93.19% H2SO. Higher concentrations are not included in the Baumh scale because density is not a unique function of concentration between 93% and 100% acid. The density of sulfuric acid versus temperature and concentration is shown in Figure 4 (50). 

Relatively high (typically 980—1200°C) temperatures are required to decompose spent acids at reasonable burner retention times. Temperatures depend on the type of spent acid. A wide variety of spent acids can be processed in this way, but costs escalate rapidly when the sulfuric acid concentration in spent acid (impurity-free basis) falls below about 75%. A few relatively uncontaminated spent acids can be reused without decomposition by evaporating the excess water in concentrators, or by mixing in fresh sulfuric acid of high concentration. Weak spent acids are frequently concentrated by evaporation prior to decomposition. 

Sulfuric Acid Concentrators. Concentrators for increasing the strength of dilute sulfuric acid by removing water have been used since the early days of the industry. A two-volume text on this subject was pubHshed ia 1924 (135) more recent discussions of the subject are also available (32,136-141). 

Typical specifications for several common types or grades of acid are shown in Table 13. Similar limits are generally used for other sulfuric acid concentrations, with the exception of turbidity values for high strength acids (and oleum) and SO2 and nitrate values in oleums. Because kon sulfate is relatively insoluble in concentrated acids, the turbidities of 98—99% H2SO4 and oleum may be higher than shown, even at acceptable total kon concentrations. 

In the reaction of ethylene with sulfuric acid, several side reactions can lead to yield losses. These involve oxidation, hydrolysis—dehydration, and polymerization, especially at sulfuric acid concentrations >98 wt % the sulfur thoxide can oxidize by cycHc addition processes (99). 

Tantalum is not resistant to substances that can react with the protective oxide layer. The most aggressive chemicals are hydrofluoric acid and acidic solutions containing fluoride. Fuming sulfuric acid, concentrated sulfuric acid above 175°C, and hot concentrated aLkaU solutions destroy the oxide layer and, therefore, cause the metal to corrode. In these cases, the corrosion process occurs because the passivating oxide layer is destroyed and the underlying tantalum reacts with even mild oxidising agents present in the system. 

Fig. 1. Aqueous solubility of copper ia copper sulfate as a function of sulfuric acid concentration at various temperatures. Reprinted with permission (37).

Hydration of Ethyl Ether. Using the same type of acid catalysts as in the hydration of ethylene to ethanol, ethyl ether can be hydrated to the alcohol. Catalysts that have been used for the hydration of ether include phosphoric acid (144), sulfuric acid (145,146), hydrochloric acid (147), metallic oxides (141,148,149) and sihcates (150). Sulfuric acid concentrations ranging from 5—25% at 200°C (144) to 63—70% at 110—135°C and 1.01—1.42 MPa (10—14 atm) (148) have been claimed. 

Sulfuric acid concentration [%] Relative humidity Manufacture [%] ml cone, sulfuric acid + ml water ... 

Table 8-4 compares sulfuric acid concentrations and the temperatures used for the sulfation of different light olefins. 

The sulfuric acid concentration should be at that required for the particular product application. Sources of sulfuric acid in LAS are as follows ... 

When primary nitro compounds are treated with sulfuric acid without previous conversion to the conjugate bases, they give carboxylic acids. Hydroxamic acids are intermediates and can be isolated, so that this is also a method for preparing them. Both the Nef reaction and the hydroxamic acid process involve the aci form the difference in products arises from higher acidity, for example, a difference in sulfuric acid concentration from 2 to 15.5 M changes the product from the aldehyde to the hydroxamic acid. The mechanism of the hydroxamic acid reaction is not known with certainty, but if higher acidity is required, it may be that the protonated aci form of the nitro compound is further protonated. 

FIGURE 28.2 Solubility of ferrous sulfate FeS04 as a function of temperature and sulfuric acid concentration. (From Eroglu, V. and Erturk, F., in Handbook of Industrial Waste Treatment, Wang, L.K. and Wang, M.H.S., Eds, Marcel Dekker, New York, 1991, pp. 293-306 Eroglu, V., Topacik, D., and Ozturk, I., Wastewater Treatment Plant for Cayirova Pipe Factory, Environmental Engineering Department, Istanbul Technical University, Turkey, 1989. With permission.)... 

The following data were obtained using identical sulfuric acid concentrations in both runs. 

BOSAC [Bofors Sulfuric Acid Concentrator] A process for recovering sulfuric acid from the production of nitro-compounds. Spent acid is concentrated by distillation, using a heat exchanger with externally heated silica tubes. Developed by Bofors Nobel Chemikur, Sweden. Douren, L., Making the Most of Sulfuric Acid, More, A. I., Ed., British Sulphur, London, 1982, 317. 

From rates of the solvolysis of 25c at different sulfuric acid concentrations in D20/CD3CN and H20/CD3CN (Fig. 13), the observed solvent KIE was found to be 0.44 (+0.02) confirming, therefore, that the transition state for solvolysis lies along... 

NOTE. The coefficient and exponent of the rate equation are strong functions of the sulfuric acid concentration. 

Ionic hydrogenation of the same bicyclic diene 382 by Et3SiH in the presence of CF3COOH at room temperature or at 80 °C via ions 387 and 388 is accompanied by transannular cyclizations (equation 139)192. The behavior of diene 382 under Ritter reaction conditions (MeCN, H2SO4) reveals new possibilities to control the transannular cyclizations (equation 140)193. Depending on the sulfuric acid concentration, the reaction temperature and the presence of a nucleophilic solvent, these transformations can be directed to the formation of either the bicyclic amides 389 and 390 having the precursor structure or the tricyclic products 391193. 

Flair tonic Unknown s Sulfuric acid Concentrated n... 

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