Abstract: The invention relates to process for dimerizing olefinic hydrocarbon feedstock, to hydrocarbon compositions and to fuel components produced by the process. According to the invention, fresh olefinic hydrocarbon feedstock is fed to a reaction zone of a system including at least one reaction zone and at least one distillation zone. The olefinic hydrocarbon feedstock is contacted with an acidic catalyst in the presence of an oxygenate at conditions in which at least a part of the olefins dimerizes. The effluent from the reaction zone is conducted to the distillation zone where dimerized reaction product is separated from effluent, and at least one flow comprising oxygenate is withdrawn from the side of at least one distillation column. The flow is circulated from distillation zone back to dimerization. The reaction mixture is recovered and optionally hydrogenated to form a parafinic reaction product.

Abstract: The present invention provides a new gasoline fuel composition, having in combination an octane value (R+M)/2 of at least 85; an aromatics content less than 25 vol. %; and a water-soluble ethers content of less than 1 vol. %. The composition has a content of olefins, at least 10 % of which is formed by heavy olefins having a boiling point above +90 “C. In particular, the composition contains up to 40 % olefins, and it contains less than 6 vol.-% of light olefins having a boiling point below +90° C., and at least 1 vol.-% heavy branched olefins having a boiling point above +90° C. Reductions in emissions of pollutants can be obtained by introducing into an automotive engine an unleaded gasoline having a composition according to invention, combusting the unleaded gasoline in said engine; introducing at least some of the resultant engine exhaust emissions into the catalytic converter; and discharging emissions from the catalytic converter to the atmosphere.