Sulfur Batch Processes

Processes for Triacetate. There are both batch and continuous process for triacetate. Many of the considerations and support faciUties for producing acetate apply to triacetate however, no acetyl hydrolysis is required. In the batch triacetate sulfuric acid process, however, a sulfate hydrolysis step (or desulfonation) is necessary. This is carried out by slow addition of a dilute aqueous acetic acid solution containing sodium or magnesium acetate (44,45) or triethanolamine (46) to neutrali2e the Hberated sulfuric acid. The cellulose triacetate product has a combined acetic acid content of 61.5%. 

The process options reflect the broad range of compositions and gas volumes that must be processed. Both batch processes and continuous processes are used. Batch processes are used when the daily production of sulfur is small and of the order of 10 kg. When the daily sulfur production is higher, of the order of 45 kg, continuous processes are usually more economical. Using batch processes, regeneration of the absorbant or adsorbant is carried out in the primary reactor. Using continuous processes, absorption of the acid gases occurs in one vessel and acid gas recovery and solvent regeneration occur in a separate reactor. 

In a batch process (176), a glass-lined jacketed iron vessel is charged with either sulfur monochloride or sulfur dichloride and about 1% of antimony trichloride as a catalyst. Chlorine is introduced into the reactor near the bottom. Liquid oleum is added to the reactor at such a rate that the temperature of the reaction mass is held at ca 25°C by the use of cooling water in the jacket. 

Later it was synthesized in a batch process from dimethyl ether and sulfur thoxide (93) and this combination was adapted for continuous operation. Gaseous dimethyl ether was bubbled at 15.4 kg/h into the bottom of a tower 20 cm in diameter and 365 cm high and filled with the reaction product dimethyl sulfate. Liquid sulfur thoxide was introduced at 26.5 kg/h at the top of the tower. The mildly exothermic reaction was controlled at 45—47°C, and the reaction product (96—97 wt % dimethyl sulfate, sulfuhc acid, and methyl hydrogen sulfate) was continuously withdrawn and purified by vacuum distillation over sodium sulfate. The yield was almost quantitative, and the product was a clear, colorless, mobile Hquid. A modified process is deschbed in Reference 94. Properties are Hsted in Table 3. 

The process for manufacture of a chloroprene sulfur copolymer, Du Pont type GN, illustrates the principles of the batch process (77,78). In this case, sulfur is used to control polymer molecular weight. The copolymer formed initially is carried to fairly high conversion, gelled, and must be treated with a peptising agent to provide a final product of the proper viscosity. Key control parameters are the temperature of polymerisation, the conversion of monomer and the amount/type of modifier used. 

The advance of sulfur trioxide as sulfating agent largely depended on advances in sulfonation/sulfation reactor development and changes in raw material quality. Undiluted sulfur trioxide cannot be used as a sulfating agent except in special cases where suitable equipment is used because of its violent nature. Sulfur trioxide diluted in an inert gas, usually air, when used in batch processes can cause excessive dehydration and dark-colored products. However, batch processes were used years ago and inert liquid solvents were often suggested or used to moderate the reaction. Inadequate reaction conditions lead to a finished product that can contain dialkyl sulfate, dialkyl ether, isomeric alcohols, and olefins whereas inadequate neutralization conditions can increase the content of the parent alcohol due to hydrolysis of the unstable acid sulfate accompanied by an increase of mineral sulfate. 

Den A batch process for making the fertilizer superphosphate. The den is the vat into which the mixture of phosphate rock and sulfuric acid is dumped after mixing. There is also a continuous-den process. Not to be confused with DEN [Deutsch - Englisch - Norwegische Gruppe], a fertilizer cartel operated in the three countries from which the name is derived from 1929 to 1930. See also Davison, Oberphos. 

Holst A batch process for making chlorine dioxide by reducing sodium chlorate with sulfur dioxide in the presence of sulfuric acid. The sodium hydrogen sulfate byproduct can be used in the Kraft papermaking process. Developed by Moch Domsjo in Sweden, in 1946. Partridge, H. de V., in Chlorine, Its Manufacture, Properties, and Uses, Sconce, J. S., Ed., Reinhold Publishing, New York, 1962, 275. 

H3C.C(CH20N02)3, (Metriol Trinitrate, MtrTN). A slightly turbid, heavy explosive oil developed before WWII by the SA Bombrini Parodi-Delfino (BPD) and manufd at the Colloferro-Roma Plant. It was obtd in 92% yield by nitrating trimethylolmethylmethane in a batch process using mixed nitric-sulfuric acid of zero water. The processes similar to that used for prepn of NG, except that high ratios of acids are used. A detailed description of prepn is... 

The ground mixture is heated to about 750 °C under reducing conditions, normally in a batch process. This can be done in directly fired kilns with the blend in lidded crucibles of controlled porosity, or muffle kilns. The heating medium can be solid fuel, oil, or gas. The sodium carbonate reacts with the sulfur and reducing agent at 300 °C to form sodium polysulfide. At higher temperatures the clay lattice reforms into a three-dimensional framework, which at 700 °C is transformed to the sodalite structure, with entrapped sodium and polysulfide ions. 

Apart from these synthetically impractical examples of hydrolysis of chloro-fluorocarbons, there are useful applications converting some chlorofluorocarbons to fluonnated carboxylic acids. As an alternative to the use of the highly corrosive fuming sulfuric acid, normally used in batch processes, a continuous hydrolytic process for converting 1,1,1-trichlorotrifluoroethane (CFC-113a), available by isomerization of CFC-113 [44], to trifluoroacetic acid has been developed [45] (equation 45). It uses metal chloride catalysts deposited on high-surface-area supports Unreacted CFC-113a can be recycled. 

USP 5717 (1866) (Accdg to Explosivst 1962, 215 246-R these patents described two original methods of prepg NG, one of them, known as the "warm method was a continuous process as for as nitration was concerned, while the other, known as the "cold method, was a batch process. In the "warm method, the cooled nitric-sulfuric acid was allowed to flow together with the glycerin into a lead funnel with perforations at its lower half. 

The high pentose yields obtained in the current study are favorable when compared to those previously reported for dilute-acid hydrolysis in batch processes (28-31). However, the hemicellulosic sugar yield reported in the literature is often expressed as xylose equivalents, which is difficult to compare to monosaccharide recovery. The highest monosaccharide recovery was obtained with low CS values, which is in agreement with previous findings for sulfuric acid-catalyzed steam explosion, in which also better hemicellulosic sugar recoveries were obtained at relatively low severities (28,32) of <2.2 (22). 

The sulfate process has, in some cases, been supplanted by the chloride process because of by-product character and disposal. However, a continuous process that uses relatively dilute sulfuric acid (25 to 60%) to temper the violent, original reaction and to reduce the amount of water-vapor-entrained particulates is available. As the process uses more dilute acid than the older batch process, more of the spent acid can be recycled. 

Achieving the required degree of desulfurization dictated electrothermal heating. Fixed-bed electrothermal furnaces of the Acheson type were initially considered for use directly with granular coke but the test results were disappointing. The product of the Acheson furnace was not uniform in its sulfur content. Adaptation of the Acheson Process, which is a batch process, presented problems in materials handling that were considered very difficult to resolve at the 10,000 tons per year capacity determined to be the... 

Cellulose acetate is manufactured by a batch process (see Fig. 12.9). There has been mention in the patent literature of a continuous system, but its utilization as a production process has not been announced. The charge of cellulose, purified, bleached, and shredded, is of the order of 800-1500 lb. It is pretreated with about one third its weight of acetic acid and a very necessary amount of water, about 6 percent of its weight. If it is too dry at the time of use, more H20 must be added to the acetic acid. A small amount of sulfuric acid may be used to assist in swelling the cellulose and to make it accessible to the esterifying mixture. 

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