Wet reduction

The Bio-FGD process converts sulfur dioxide to sulfur via wet reduction (10). The sulfur dioxide gas and an aqueous solution of sodium hydroxide are contacted in an absorber. The sodium hydroxide reacts with the sulfur dioxide to form sodium sulfite. A sulfate-reducing bacteria converts the sodium sulfite to hydrogen sulfide in an anaerobic biological reactor. In a second bioreactor, the hydrogen sulfide is converted to elemental sulfur by Thiobacilh. The sulfur from the aerobic second reactor is separated from the solution and processed as a sulfur cake or liquid. The process, developed by Paques BV and Hoogovens Technical Services Energy and Environment BV, can achieve 98% sulfur recovery. This process is similar to the Thiopaq Bioscrubber process for hydrogen sulfide removal offered by Paques. 

Ni Catalyst from Ni Formate (by Wurster) (Wet Reduction of Nickel Formate for Oil Hardening).42 A mixture of 4 parts oil and 1 part nickel formate is heated steadily to about 185°C at atmospheric pressure. At 150°C the initial reaction begins, and at this point or sooner hydrogen gas is introduced. The reaction becomes active at 190°C with the evolution of steam from the water of crystallization. The temperature holds steady for about 30 min until the moisture is driven off and then rises rapidly to 240°C. It is necessary to hold the charge at 240°C, or a few degrees higher, for 30 min-1 h to complete the reaction. The final oil-nickel mixture contains approximately 7% Ni. With equal weights of oil and nickel formate, the final oil-nickel mixture contains approximately 23% Ni. 

Qiersieden Schwedes, "Experiences with machines used for wet reduction in the Chemical Industry" Chemie Ingenieur Technik I982... 

Wet reduction of Pt/Al203 catalysts using sodium borohydride was found to be effective for the removal of chloride, thereby increasing the activity and dispersity as compared to catalysts prepared by impregnation and direct calcination. 

Two nickel catalyst manufacturing processes are in use wet reduction and dry reduction, with the latter being the one of greater importance today. 

Changes in the surface concentrations of the promoter elements are also dependent on the mode of reduction. Subsequent to wet reduction, potassium and aluminum are destributed at the surface, while their concentrations are lowered when dry hydrogen is used. Redispersion of aluminum occurred in samples of both catalysts that had been reduced in dry hydrogen during ammonia synthesis. The redispersion was complete within ca 30 hours of exposure to synthesis gas mixture and did not occur when the samples were kept at 790 K in pure hydrogen. 

It is interesting to note the large difference in potassium dispersion as indicated by the iron-to-potassium ratios. Wet reduction seems to support the formation of a potassium species which is dispersed over the surface of the catalyst. 

Under wet reduction conditions, the amount of zero-valent iron is much smaller than after dry reduction, which is in agreement with the UPS data. The peak maximum for the oxidized species lying between the typical binding energies of ferrous and ferric iron is not indicative of a special chemical state. This arises from a superposition of two asymmetric subspectra, each centered at the typical ferrous and ferric positions. Comparison of the sample spectrum with the spectrum of magnetite shows that the amount of ferrous ions in the catalyst is much larger... 

In Fig. 2.41, a raw data set from a wet reduction experiment is shown. The catalyst had, however, been stored in air for several years before it was used. Segregation of potassium compounds had led to a color change from black to gray. The reduction was carried out on such a gray surface, cut from the catalyst lump using a diamond saw. The left-hand side of Fig. 2.41 shows iron 2p data... 

The broadening of the spectrum upon treatment at 790 K is similar to observations made when calcium carbonate single crystals are subject to argon ion bombardment. The defects induced in the calcium oxide component of the catalyst cannot be caused by an initial reduction of the oxide, because calcium oxide is stable to hydrogen at 790 K. The defects may be indicative of the formation of a ternary calcium iron oxide since there is no observed increase in the dispersion of calcium, which would be associated with a disintegration of the CaO crystals. It should be pointed out that the other structural promoter element, aluminum, exhibits the same spectral changes in its A12 emission. The dispersion of the alumina increases, however, with reduction of the catalyst, particularly when the wet reduction method is applied (see Table 2.1). 

Wet reduction Insoluble nickel formate is precipitated by adding sodium formate to a strong solution of a nickel salt. Alternatively, formic acid can be added to precipitated nickel hydroxide or carbonate. The precipitate is filtered and washed with minimum water to remove impurities and dried. Catalyst is suspended in dry saturated oil and slowly heated first to about 200 C and then to about 250°C. The hydrate first decomposes at up to 180 C and finally the formate itself decomposes to produce finely divided nickel at about 200°C. Nickel can be filtered from the mixture and suspended in fresh oil. The suspension forms flakes as it solidifies and the catalyst is ready for use. 

Lattice models have been studied in mean field approximation, by transfer matrix methods and Monte Carlo simulations. Much interest has focused on the occurrence of a microemulsion. Its location in the phase diagram between the oil-rich and the water-rich phases, its structure and its wetting properties have been explored [76]. Lattice models reproduce the reduction of the surface tension upon adsorption of the amphiphiles and the progression of phase equilibria upon increasmg the amphiphile concentration. Spatially periodic (lamellar) phases are also describable by lattice models. Flowever, the structure of the lattice can interfere with the properties of the periodic structures. 

Sometimes the reaction stops suddenly it is then necessary to add a further 10 ml. of 20 per cent, sodium hydroxide solution and warm to the boiling point this causes the reaction to continue. Occasionally, the reduction becomes very vigorous a wet towel and a bath of ice water should be kept close at hand. 

Naphthalenesulfonic acids are important chemical precursors for dye intermediates, wetting agents and dispersants, naphthols, and air-entrainment agents for concrete. The production of many intermediates used for making a2o, a2oic, and triphenylmethane dyes (qv) involves naphthalene sulfonation and one or more unit operations, eg, caustic fusion, nitration, reduction, or amination. 

Framing. The framed bar process is by far the oldest and the most straightforward process utilized in the production of bar soaps. The wet base soap is pumped into a heated, agitated vessel commonly referred to as a cmtcher. The minor ingredients used in soap bars such as fragrance or preservative are added to the wet soap in the cmtcher or injected in-line after reduction of product stream temperature. The hot mixture is then pumped into molds and allowed to cool. 

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