The present disclosure provides a catalyst system that is capable of selectively hydrogenating (2,3)/(4,5) and (2,3)/(5,6) dienones with hydrogen gas. Specifically, the present disclosure provides catalysts capable of providing high selectivity for the reduction even in the absence of catalyst poisons such as pyridine, pyrazine, quinoline, and quinoxaline

A method of making a catalyst for use in oligomerizing an olefin comprising a chromium-containing compound, a pyrrole-containing compound, a metal alkyl, a halide-containing compound, and optionally a solvent, the method comprising contacting a composition comprising the chromium-containing compound and a composition comprising the metal alkyl, wherein the composition comprising the chromium-containing compound is added to the composition comprising the metal alkyl.

The present invention relates to a ligand compound, a catalyst system for ethylene oligomerization, and a method for ethylene oligomerization using the same. The catalyst system for ethylene oligomerization according to the present invention not only has excellent catalytic activity but also shows more improved liquid olefin selectivity, and enables more effective preparation of an alpha-olefin through the oligomerization of ethylene because it is particularly possible to control the selectivity to 1-hexene or 1-octene.

A method of making a catalyst for use in oligomerizing an olefin comprising a chromium-containing compound, a pyrrole-containing compound, a metal alkyl, a halide-containing compound, and optionally a solvent, the method comprising contacting a composition comprising the chromium-containing compound and a composition comprising the metal alkyl, wherein the composition comprising the chromium-containing compound is added to the composition comprising the metal alkyl.

The present invention describes a novel catalytic composition comprising at least one nickel complex, said complex being obtained from a mixture comprising at least one nickel precursor A with at least one imino-imidazole ligand B and a method of oligomerization of olefins using said catalytic composition.

Systems and methods for catalyst activation in ethylene reactions are described. Systems and methods may include pre-mixing at least one ligand and at least one chromium source in at least one solvent to form a pre-mixed composition; activating the pre-mixed composition with an activator to form an activated composition; and supplying the pre-activated composition to a reactor.

A process for the oligomerization of ethylene to predominantly 1-hexene or 1-octene or mixtures of 1-hexene and 1-octene includes contacting ethylene with a catalyst under ethylene oligomerization conditions. The catalyst comprises a source of chromium, a diphosphine ligating compound, and optionally an activator. The diphosphine ligating compound includes at least one optionally substituted fused cyclic structure including at least two rings, the optionally substituted fused cyclic structure including a 5- to 7-membered aromatic first ring bonded to a phosphorus atom, the aromatic first ring being fused to a 4- to 8-membered heterocyclic second ring, the heterocyclic second ring including a heteroatom which is separated by two ring atoms along the shortest connecting path from the phosphorous atom that is bonded to the first aromatic ring.

A process for the oligomerization, preferably the tetramerization, of ethylene to predominantly 1-hexene or 1-octene or mixtures of 1-hexene and 1-octene includes contacting ethylene with a catalyst under ethylene oligomerization conditions. The catalyst comprises a source of chromium, a diphosphine ligating compound, and optionally an activator. The diphosphine ligating compound includes at least one substituted aromatic ring bonded to a phosphorous atom. The substituted aromatic ring is substituted at a ring atom adjacent to the ring atom bonded to the respective phosphorous atom with a group Y, where Y is of the form AR.sup.EWG, A being O, S or NR.sup.5, where R.sup.5 is a hydrocarbyl, heterohydrocarbyl or organoheteryl group, and R.sup.EWG is an electron withdrawing group.

Catalyst systems suitable for tetramerizing ethylene to form 1-octene may include a catalyst including a chromium compound coordinated with a ligand and a co-catalyst including an organoaluminum compound. The ligand may have a chemical structure according to Formula (1), wherein R.sup.1 is a (C.sub.3-C.sub.20) substituted or unsubstituted hydrocarbyl group; R.sup.2, R.sup.3, R.sup.4, and R.sup.5 are independently chosen from (C.sub.1-C.sub.50) hydrocarbyl groups; and R.sup.1 and N are in a cis configuration.

A method for reducing fouling in an oligomerizing reactor that includes upgrading C.sub.2 to C.sub.4 hydrocarbons within the oligomerizing reactor in the presence of a fouling inhibitor having a particle size D.sub.50 of less than 100 m and forming linear alpha olefins and polymer during the oligomerizing, wherein the fouling inhibitor changes the morphology of the polymer.