Abstract: Gum-free fuel components containing alkyl tert.-alkyl ethers have been found which can be prepared by reacting a crude hydrocarbon mixture containing gum-forming constituents and containing one or more tert.-olefins, simultaneously with alkanols and H.sub.2 on a certain exchanger in the H.sup.+ form containing one or more metals of sub-group VI, VII or VIII of the periodic table of the element in element form, in the liquid phase at 30.degree. to 140.degree. C.

Abstract: In the removal of pure aromatics from aromatic-containing hydrocarbon mixtures by liquid-phase extraction or extractive distillation using a selective solvent, the specific cost of separation can be reduced at the same yield of aromatics or the yield of aromatics can be increased at the same specific cost of separation if the liquid-phase extraction or the extractive distillation is carried out in the presence of a reactive solid. At the same time, substantially aromatic-free raffinates are obtained.

Abstract: Pure tert.-olefins are prepared from mixtures of hydrocarbons, which contain at least one such tert.-olefin, by reaction with an alkanol to give the corresponding alkyl tert.-alkyl ethers, and subsequent cleavage of these ethers back to the corresponding pure tert.-olefins and the alkanol, and the separation of the pure tert.-olefin from the alkanol. For this, the alkanol present after the cleavage of the ether is separated from the tert.-olefin to the extent of 60 to 99% by weight by distillation, and the residual amount of alcohol in the olefin fraction is removed by adsorption from this fraction onto a synthetic ion exchanger as an absorber resin. The admixture of the alkanol to the mixture of hydrocarbons with at least one tert.-olefin is carried out partly by using the alkanol fraction arising from the separating off of the pure tert.-olefin, and partly by desorption of the alkanol from the absorber resin with the aid of the mixture of hydrocarbons containing at least 1 tert.-olefin.