Abstract: A method for dimerization of olefins with a number of carbon atoms of at most 10 which comprises intermixing, in a medium of solvents selected from the group consisting of hydrocarbon solvents and halogenated hydrocarbon solvents at a temperature ranging from -20.degree. to +100.degree. C under a pressure of from 1 to 45 atm, of at least one of said olefines with a two-component catalyst consisting of an organoaluminum compound of the formula R.sub.n AlX.sub.3-n, wherein R is an alkyl with a number of carbon atoms of at most 8, X is a halogen, n = 1 or 2, and a graft-copolymer, swellable in said solvents, of a rubber selected from the group consisting of natural, synthetic carbo-chain and vinyl-containing siloxane rubbers, with vinylpyridine; said copolymer containing 0.5 to 40% by weight of polyvinylpyridine fragments complexed with a nickel salt; molar ratio between said organoaluminum compound and said nickel salt ranging from 1:1 to 100:1.

Abstract: A method of purifying crude petroleum and primary refining products of their sulfur, sulfur compounds, nitrogen- and oxygen-containing compounds which comprises treating crude petroleum or virgin petroleum stocks with complexes or salts of transition metals (.pi. -complexes of transition metals), salts or .pi. -allylic complexes of platinum metals and carbonyl complexes of transition metals at a temperature of 80.degree.-120.degree. C, followed by separating the purified target product from the resulting reaction mixture. stabilityThe method of the invention makes it possible to effect petroleum product purification as a single-stage process and, in contrast to the available methods, dispenses with the employment of hydrogen, catalysts, and aqueous alkalies.