GB277394A - Improvements in the manufacture and production of organic compounds - Google Patents

Abstract

277,394. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). March 13, 1926. Aromatic hydrocarbons; phenols; alcohols.- Aromatic hydrocarbons or phenols or tar fractions containing them are converted into lower aromatic hydrocarbons or phenols by passing their vapour in admixture with more than twice their volume of water vapour at an elevated temperature over catalysts possessing both hydrating and dehydrogenating properties. The catlysts may be single substances possessing both properties or mixtures of substances, one of which possesses hydrating and other dehydrogenating properties ; nickel, cobalt, iron, copper. compounds of light metals (alkali, alkaline earth, and earth metals), zinc or its compounds, and difficulty reductible oxides of metals belonging to the fourth to seventh periodic groups, e.g. oxides of titanium vanadium, chromium, and manganese, are preferably present. The process is specially applicable to the treatment of fractions from coal tar, brown coal tar, and low-temperature tar, especially naphthalene and middle, oils, heavy benzol and creosote oil. which are transformed into benzene and its homologues. The starting materials, which are preferably freed from contact poisons such as sulphur, arsenic compounds, and metallic carbonyls, may be preliminarily hydrogenated. Temperatures of 300-700‹ C. and preferably 300-500‹ are employed; inert gases may be present. The gas mixtures obtained, which mainly comprise carbon dioxide and hydrogen are useful for the catalytic manufacture of alcohols. According to the examples, (1) o-cresol vapour and steam are passed over a catalyst prepared by soaking bauxite with copper nitrate and heating it in a current of hydrogen; a mixture of o-cresol and phenol is condensed; (2) naphthalene, freed from sulphur, is conducted in the vapour phase mixed with steam over a paste of nickel sesquioxide, alumina and china clay which has been reduced in hydrogen; on cooling the products an oil consisting of benzene and small quantities of its homologues separates out, whilst a mixture of carbon dioxide and hydrogen passes on; under other working conditions, homologues of benzene, e.g. toluene and o-xylene, may be obtained; (3) a mixture of naphthalene and phenols is vapourized and passed with hydrogen over a catalyst prepared by reducing a mixture of ammonium molybdate and zinc oxide; the resulting product is mixed, without cooling, with steam and passed over the catalyst described in the preceding example; the hydrocarbons formed during the first stage by reduction of the phenols become, converted, along with the naphthalene, into benzene and its homologues during the second stage.