Sulphuric acid process improvement

The raw material has to be washed to remove impurities. Diluted sodium hydroxide allows the removal of phenols and benzonitrile, and diluted sulphuric acid reacts with pyridine bases. The resulting material is distilled to concentrate the unsaturated compounds (raw feedstock for coumarone-indene resin production), and separate and recover interesting non-polymerizable compounds (naphthalene, benzene, toluene, xylenes). Once the unsaturated compounds are distilled, they are treated with small amounts of sulphuric acid to improve their colour activated carbons or clays can be also used. The resulting material is subjected to polymerization. It is important to avoid long storage time of the feedstock because oxidation processes can easily occur, affecting the polymerization reaction and the colour of the coumarone-indene resins. 

The use of maleic anhydride as a compatiblizer between wood particles and bisphenol A-based polyesters resins has been investigated (Han etal., 1991). In this study, the MA was added directly to the composition of woody matrix filler and resin rather than by pre-modification of the wood. It was found that composite properties were improved by addition of MA, probably due to esterification of the wood occurring during the kneading process. The modification of sawdust using maleic anhydride has been performed in order to provide a compatible filler for polyester resins (Marcovich etal., 1996). Modification was performed at room temperature using a solution of maleic anhydride in acetone, in some cases catalysed with sulphuric acid. It was claimed that bonding occurred under these mild conditions from IR spectroscopic evidence only. 

Conversion of substituted nitrobenzenes to the arylhydroxylamine is easily achieved by reduction in neutral or slightly acid solution. In the first classical experiments, Haber [35] used a platinum cathode and ammonia ammonium chloride buffer and die process was improved by Brand [57] using either a nickel or silvered copper cathode in an acetate buffer. The hydroxylamine can also be obtained from reduction in dilute sulphuric acid provided tire temperature is kept below 15° C to suppress furtlier reduction [58]. This electrochemical route to arylhydroxylamines due to Brand is superior to the chemical reduction using zinc dust and ammonium chloride solution. The latter process is known to give variable yields depending on... 

Having followed the manufacture to this point, one must now pass on to another step, from the intermittent to the continuous process, as practised at present. It is easy to see that had Dr. ROEBUCK burned his sulphur in a properly constructed apparatus, and introduced the resulting sulphurous acid into his chamber at one end, drawing oft the residual gases at the other, he would have improved his method, and escaped many inconveniences. 

Proposed Improvements in Mamfaetwring Sulphuric Acid.—The efforts of inventors in connection with sulphuric acid, would appear to have been directed to the substitution of some apparatus of smaller bulk, and less costly In construction, than the leaden chambers ordinarily employed. Perhaps the simplest process embodying the above idea is that of Messrs. M Douoall and Eawsonj who included it in a patent obtained by them in 1848, It consists essentially In passing a stream of sulphurous acid gas through nitric acid by which sulphuric add and binoxido of nitrogen — NOj—are obtained as follows —... 

CANDLE.—Read, in connection with the processes described at pages 430,431 —The operations of saponification of the fat, and decomposition of the lime-soap by sulphuric acid, have been hitherto effected in open vessels, under the ordinary pressure of the atmosphere. An improvement on this plan has been recently proposed by M, Delapchiek, of Besangoo, who substitutes dose vessels in Order to saponify the fat. Wash and decompose the lime-soap under a pressure of about twenty-two pounds to the square inch, by which the operations are considerably facilitated, and their duration shortened. The products by this process are said to be superior to those obtained in open vessels, and a considerable economy of flaid is effected. The apparatus consists essentially of a horizontal boiler, with a man-hole and two safety valves at the top, The heat is furnished by a large steam-pipe, running in a depression along the bottom of the boiler. The... 

A special focus of the development regarding solar thermochemical processes is the high temperature endothermic decomposition of sulphuric acid. The solarisation of this step was part of the R D activities of the European project HYTHEC (HYdrogen THErmochemical Cycles) with an emphasis on components development and process improvement (Noglik, 2009). 

The major availability consumptions are in combustion furnace, uaste heat boiler and absorption sections. It is not possible to eliminate these consumptions in sulphuric acid plant for the process system being folloued presently. Houever marginal improvements can be achieved by high temperature combustion system, use of gas turbines, generation of high pressure superheated steam and cocurrent absorption system. 

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