Fixed sulfuric acid

And indeed when Stahl fixed sulfuric acid (made it a solid by allowing it to react with potassium hydroxide), then heated it with charcoal, he obtained liver of sulfur ( 2, potassium polysulfide). This is the same dark brown amorphous mass obtained when pure sulfur is fused with potassium hydroxide, so he concluded that he had his sulfur back, and the phlogiston theory worked. 

Barium sulfate [7727-43-7] BaSO, occurs as colorless rhombic crystals, mp 1580 °C (dec) sp gr 4.50 solubihty 0.000285 g/100 g H2O at 30°C and 0.00118 at 100°C. It is soluble in concentrated sulfuric acid, forming an acid sulfate dilution with water reprecipitates barium sulfate. Precipitated BaSO is known as blanc fixe, prepared from the reaction of aqueous solutions of barium sulfide and sodium sulfate. 

An advanced solution to the problem of decreasing the free mobility of the electrolyte in sealed batteries is its gel formation. By adding some 5-8 wt.% of pyrogenic silica to the electrolyte, a gel structure is formed due to the immense surface area (-200-300 m2 g ) of such silicas, which fixes the sulfuric acid solution molecules by van der Waals bonds within a lattice. These gels have thixotropic properties i.e., by mechanical stirring they can be liquefied and used to Filled into the... 

A component in a mixture is a substance of fixed composition that can be mixed with other components to form a solution. For thermodynamic purposes, the choice of components is often arbitrary, but the number is not. Thus, aqueous sulfuric acid solutions consist of two components, usually designated as H2S04 and H20. But SO3 and HiO could also be considered as the components since SO3, H2SO4, and H2Q are related through the equation... 

Chlorinating the aqueous waste sludge suspension (to oxidize the chromium) at temperatures of 20 to 80°C and pH values between 4 and 13. The chlorinated sludge is then acidified with sulfuric acid to a pH of 1.0 to 3.0. The insoluble components are then separated, followed by the separation of the chromium(VI) from the solution using a fixed-bed anion exchanger (at pH values of <3). 

Fixed Bed Reactors. In its most basic form, a fixed bed reactor consists of a cylindrical tube filled with catalyst pellets. Reactants flow through the catalyst bed and are converted into products. Fixed bed reactors are often referred to as packed bed reactors. They may be regarded as the workhorse of the chemical industry with respect to the number of reactors employed and the economic value of the materials produced. Ammonia synthesis, sulfuric acid production (by oxidation of S02 to S03), and nitric acid production (by ammonia oxidation) are only a few of the extremely high tonnage processes that make extensive use of various forms of packed bed reactors. 

Industrial scale production of sulfuric acid is dependent on the oxidation of sulfur dioxide to sulfur trioxide in fixed bed catalytic reactors. 

Centaur A process for reducing sulfur dioxide emissions from sulfuric acid plants. An activated caibon with both absorptive and catalytic properties is used. The technology uses fixed beds of Centaur carbon to oxidize sulfur dioxide to sulfuric acid in the pores of the carbon. The sulfuric acid is recovered as dilute sulfuric acid, which is used a make-up water in the sulfuric acid production process. Developed by Calgon Carbon Corporation in the 1990s. Calgon Carbon and Monsanto Enviro-Chem operated a Centaur pilot plant at an existing sulfuric acid facility in 1996. 

In a fixed-bed catalytic reactor for a fluid-solid reaction, the solid catalyst is present as a bed of relatively small individual particles, randomly oriented and fixed in position. The fluid moves by convective flow through the spaces between the particles. There may also be diffusive flow or transport within the particles, as described in Chapter 8. The relevant kinetics of such reactions are treated in Section 8.5. The fluid may be either a gas or liquid, but we concentrate primarily on catalyzed gas-phase reactions, more common in this situation. We also focus on steady-state operation, thus ignoring any implications of catalyst deactivation with time (Section 8.6). The importance of fixed-bed catalytic reactors can be appreciated from their use in the manufacture of such large-tonnage products as sulfuric acid, ammonia, and methanol (see Figures 1.4,11.5, and 11.6, respectively). 

The scission reaction was carried out with a fixed addition of 1.50g of the dry resin, 10 mg of ferrous sulfate heptahydrate and 50 ml of 3% w/v hydrogen peroxide in a round Pyrex flask. The evolved carbon dioxide was vented to the atmosphere through serial traps containing sulfuric acid followed by a soda lime sorption tube. The magnetically stirred reaction flask was submerged in an oil bath heated with an immersed electrical coil and a magnetic stirrer positioned below the bath. The temperature was maintained at 50 +/- 1 C. After varied times 1.0 ml samples of liquid were withdrawn. There were fewer than six withdrawals in a given reaction sequence. 

Nanotube arrays several microns in length can be fabricated using KF (or NaF with identical results) electrolytes of variable pH [22], a summary of which is presented in Table 5.3. Prior to KF addition, the desired pH was obtained by adding NaOH, sulfuric acid (pH 1-2), sodium hydrogen sulfate, or citric acid (pH 2.5-7.5). The F concentration was held fixed at 0.1 mol/L. In 0.1 mol/L F and 1 mol/L H2SO4 medium, the potential window for nanotube formation is 10-25V (Samples 01 to 08). Outside of this potential range no nanotubes were formed (Samples 01 and 08). In Sample... 

Marggraf then collected clays from various places in Germany, Silesia, and Poland, and distilled them with sulfuric acid, but obtained no satisfactory crystals of alum. When he added fixed alkali in the proper amount, however, he obtained beautiful, large crystals of it (74). 

Esprits acides acids Acide du sel marin hydrochloric acid Acide nitreux nitric acid Acide vitriolique sulfuric acid Sel alcali fixe carbonates of potassium and sodium... 

Fixed- or packed-bed reactors refer to two-phase systems in which the reacting fluid flows through a tube filled with stationary catalyst particles or pellets (Smith, 1981). As in the case of ion-exchange and adsorption processes, fixed bed is the most frequently used operation for catalysis (Froment and Bischoff, 1990 Schmidt, 2005). Some examples in the chemical industry are steam reforming, the synthesis of sulfuric acid, ammonia, and methanol, and petroleum refining processes such as catalytic reforming, isomerization, and hydrocracking (Froment and Bischoff, 1990). 

Run 5. Commercial nitrogen used was purified by passing it through an alkaline solution of pyrogallol and a series of concentrated sulfuric acid, silica gel, and anhydrous calcium chloride tubes. The flow rate of nitrogen was fixed at 40 ml./min. Unreacted cyclohexene and low boiling products were removed from the collected products at reduced pressure. 

The bomb contents are digested with concentrated hydrochloric acid, and material still undissolved is then digested with potassium hydroxide and hydrogen peroxide. A crude separation is made by a sulfide precipitation from the combined digestion solutions. The sulfides are dissolved in aqua regia, the solution is evaporated, and antimony in the residue is reduced to antimony (III) with hydroxylamine hydrochloride. The sample, in ammonium thiocyanate-hydrochloric acid medium, is loaded onto a Dowex 2 column (SCN" form). Arsenic and other impurities are eluted with aliquots of more dilute ammonium thiocyanate-hydrochloric acid solutions. Antimony is eluated with sulfuric acid and fixed in solution by addition of hydrochloric acid. The activity of the solution caused by the 0.56 MeV y-ray of 2.8-day 122Sb is counted. 

The current method (3, 4, 6, 22) involves steam distillation to separate the volatile (primarily acetic) acids from the non-volatile (fixed) acids. Special equipment has been devised for this separation (6). Sulfurous and sorbic acid content can be corrected, or the sulfurous acid may be removed (33). Carbon dioxide must be removed so that it does not interfere with the test (6, 33). An automated procedure is also available (34) which measures the volatile acids in the distillate at 450 nm using bromophenol blue. 

The surfactant, cetyltrimethylammonium bromide, was dissolved in water to obtain a clear solution, in which the first swelling agent (decane) was then added drop by drop with stirring. After ten minutes stirring at room temperature, the second swelling agent (TMB) was introduced. Sodium silicate was added to the obtained micellar solution and the pH value was adjusted with sulfuric acid. The pH value and surfactant/silicium molar ratio was fixed at 10 and 0.62 according to the protocol established previously for conventional MCM-41 synthesis... 

Traditionally, ethanol has been made from ethylene by sulfation followed by hydrolysis of the ethyl sulfate so produced. This type of process has the disadvantages of severe corrosion problems, the requirement for sulfuric acid reconcentration, and loss of yield caused by ethyl ether formation. Recently a successful direct catalytic hydration of ethylene has been accomplished on a commercial scale. This process, developed by Veba-Chemie in Germany, uses a fixed bed catalytic reaction system. Although direct hydration plants have been operated by Shell Chemical and Texas Eastman, Veba claims technical and economic superiority because of new catalyst developments. Because of its economic superiority, it is now replacing the sulfuric acid based process and has been licensed to British Petroleum in the United Kingdom, Publicker Industries in the United States, and others. By including ethanol dehydrogenation facilities, Veba claims that acetaldehyde can be produced indirectly from ethylene by this combined process at costs competitive with the catalytic oxidation of ethylene. 

To test for RDX, a few crystals of the material for test fixe placed in the indenture of a white spot plate and.l drop of test solution (lmg of DPhA in 10ml of 85% sulfuric acid) is added. A strong blue color in 1 minute indicates RDX. A blue color is obtd with HMX only after 5 mins or longer has elapsed (Ref 1)... 

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