Abstract: Propylene production processes are discussed herein. The propylene production processes may include contacting an olefin feed including butene with ethylene in the presence of a catalyst system including a metathesis catalyst under reaction conditions sufficient to form a product stream including propylene, wherein the metathesis catalyst includes molybdenum and the reaction conditions include a reaction temperature of less than 250° C.

Abstract: Propylene production processes are discussed herein. The propylene production processes may include contacting an olefin feed including butene with ethylene in the presence of a catalyst system including a metathesis catalyst under reaction conditions sufficient to form a product stream including propylene, wherein the metathesis catalyst includes molybdenum and the reaction conditions include a reaction temperature of less than 250° C.

Abstract: A class of bridged or unbridged metallocene compounds is disclosed, wherein the cyclopentadienyl ligands have two or four adjacent substituents forming one or two alkylenic cycles of from 4 to 8 carbon atoms. These metallocenes are useful as catalyst components for the polymerization of olefins, particularly for the (co)polymerization of ethylene and for the polymerization of propylene.

Abstract: Metallocene compounds having the general formula (I): R1 are hydrocarbon groups, R2 are hydrogen or hydrocarbon groups; M is a transition metal of group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table; M′ is a transition metal selected from those belonging to group 3 or to the lanthanide or actinide groups in the Periodic Table; X is a monoanionic ligand; p is an integer of from 0 to 3, being equal to the oxidation state of M minus two; q is an integer from 3 to 5; and n is an integer from 1 to 4, when the six-membered rings of formula (Ia) are not perhydrated, and is an integer of from 0 to 4, when the six-membered rings of formula (Ia) are perhydrated as well as in the compound of formula (Ib).

Abstract: A class of bridged or unbridged metallocene compounds is disclosed, wherein the cyclopentadienyl ligands have two or four adjacent substituents forming one or two alkylenic cycles of from 4 to 8 carbon atoms.

Abstract: It is disclosed a new class of bridged metallocene compounds of formula (I): wherein R1 and R2 can be hydrogen, alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl radicals; R3 and R4 form a condensed, 5- to 8-membered, aliphatic, aromatic or heterocyclic ring; M is a transition metal of groups 3, 4, 5, lanthanide or actinide; X is hydrogen, halogen, —R, —OR, —OSO2CF3, —OCOR, —SR, —NR2 or PR2, wherein R is an hydrocarbon substituent; and p is 0-3. Furthermore, a catalyst system for olefin polymerization based on the above bridged metallocene compounds and the ligands for their preparation are disclosed.

Abstract: A class of bridged or unbridged metallocene compounds is disclosed, wherein the cyclopentadienyl ligands have two or four adjacent substituents forming one or two alkylenic cycles of from 4 to 8 carbon atoms. These metallocenes are useful as catalyst components for the polymerization of olefins, particularly for the (co)polymerization of ethylene and for the polymerization of propylene.

Abstract: A process for preparing bis-cyclopentadienyl compounds bridged by a methylene group is reported, said process comprising reacting formaldehyde with a cyclopentadienyl compound in the presence of a base and of a solvent having a dielectric constant (.epsilon.), measured at 25.degree. C., higher than 7. The bridged compounds, obtainable in high yields with this simple single-step process, can be used to prepare ansa-metallocenes, active as catalyst components in the polymerization of olefins.