Purification of regenerated sulfuric acid from crude-benzole-fraction washing

At the present stage of development in chemical technology, any newly developed and operated process must not only have high technical and economic performance indices but also ensure that no toxic wastes are produced to pollute the environment. From this point of view, the future of the sulfuric-acid process for refining aromatic hydrocarbons and naphthalene hinges on the problem of eliminating its waste products (acid sludge and spent sulfuric acid). The recycling of spent sulfuric acid does more than merely overcome an environmental pollution problem, since it lowers the costs of ammonium sulfate production in proportion to the price ratios: sulfuric acid accounts for 28-32 percent of the total production costs for ammonium sulfate. Research has shown that various sulfo-acids can be extracted from spent sulfuric acid by salting out and extraction with aliphatic alcohols. A closed-cycle flowsheet is proposed for the purification of regenerated acid.