| 摘要 |
<p>Alkanes or alkenes of 6-12 carbon atoms are aromatized, under pressure and in the presence of hydrogen, at 400-600 DEG C. with catalysts containing chromium oxide and alumina in molecular ratios (60-20) : (40-80), and a potassium compound equivalent to 1-8 per cent by weight of potassium based on the mixture of oxides. The oxides may be obtained from the mixed hydroxides prepared by precipitation with ammonia from dilute solutions of the salts, e.g. nitrates. The potassium compound is preferably free from halogen and may be added as the hydroxide, carbonate or nitrate. Pressures of 2-10, preferably 3-6 atmos. are generally used, and 5-20, preferably 10-15 mols. of hydrogen per mol. of hydrocarbon. With feed hydrocarbons such as gasoline fractions containing non-hydroaromatic naphthenes, the latter should first be removed as by isomerizing with aluminium chloride. Alkenes in the product may be converted to alkanes by passing the product over the same or similar catalysts at 400-500 DEG C. High boiling products should be removed before recycling of the product over the same or additional catalyst. Catalyst regeneration is effected with steam and, if desired, hydrogen, preferably at about 650 DEG C. In an example, a 90-10 per cent by weight n-heptane-methylcyclopentane mixture is passed over a catalyst comprising Al2O3 and Cr2O3 in 60 : 40 mol. per cent ratio, and 3 per cent by weight potassium in the form of KOH, at 540 DEG C. and 4 atmos. Specification 534,236 is referred to. The Specification as open to inspection under Sect. 91 comprises additional examples, wherein gasolines containing alkanes, aromatics, and 5 and 6 carbon naphthenes are treated to give highly aromatic products. The alkene content is reduced by recycling over the regenerated catalyst with hydrogen at 400 DEG C. Heptane is aromatized at 525 DEG C. This subjectmatter does not appear in the Specification as accepted.</p> |
