Process for Reducing the Light Oligomer Content of Polypropylene Oils
Disclosed herein are catalyst systems containing an alpha-diimine nickel halide complex, a chemically-treated solid oxide, and an optional co-catalyst. These catalyst systems can be used to reduce the light oligomer content of propylene oligomer streams, for instance, by oligomerizing olefin feedstocks containing C 6 to C 27 propylene oligomers to produce oligomer compositions having higher molecular weights.
1 . A process comprising:
contacting an olefin feedstock comprising C 6 to C 27 propylene oligomers with a catalyst composition comprising (i) an alpha-diimine nickel halide complex, (ii) a chemically-treated solid oxide, and (iii) optionally, a co-catalyst, to produce an oligomer composition, wherein a number-average molecular weight (Mn) of the oligomer composition is greater than that of the olefin feedstock.
2 . The process of claim 1 , wherein the Mn of the oligomer composition is greater than that of the olefin feedstock by from about 5% to about 100%.
3 . The process of claim 1 , wherein a ratio of a total of C 18 to C 27 oligomers to a total of C 6 to C 15 oligomers of the oligomer composition is greater than that of the olefin feedstock by from about 25% to about 2500%.
4 . The process of claim 1 , wherein:
the catalyst composition comprises a co-catalyst; and
the chemically-treated solid oxide comprises a fluorided solid oxide and/or a sulfated solid oxide.
5 . The process of claim 4 , wherein the co-catalyst comprises an organoaluminum compound.
6 . The process of claim 1 , wherein the chemically-treated solid oxide comprises fluorided alumina, sulfated alumina, fluorided silica-alumina, sulfated silica-alumina, fluorided silica-coated alumina, fluorided-chlorided silica-coated alumina, sulfated silica-coated alumina, or any combination thereof.
7 . The process of claim 1 , wherein the alpha-diimine nickel halide complex comprises an alpha-diimine nickel chloride complex.
8 . The process of claim 1 , wherein the alpha-diimine nickel halide complex comprises an alpha-diimine nickel bromide complex.
9 . The process of claim 1 , wherein the alpha-diimine nickel halide complex has formula (I):
wherein:
each R independently is H, a halide, a C 1 to C 36 hydrocarbyl group, a C 1 to C 36 halogenated hydrocarbyl group, a C 1 to C 36 hydrocarboxy group, or a C 1 to C 36 hydrocarbylsilyl group;
R 1 and R 2 independently are H, a halide, a C 1 to C 36 hydrocarbyl group, a C 1 to C 36 halogenated hydrocarbyl group, a C 1 to C 36 hydrocarboxy group, or a C 1 to C 36 hydrocarbylsilyl group, or R 1 and R 2 are linked to form a ring or ring system; and
each X independently is a halide.
10 . The process of claim 9 , wherein:
each R independently is H or a C 1 to C 8 alkyl group;
R 1 and R 2 independently are H or a C 1 to C 18 hydrocarbyl group; and
each X independently is Cl or Br.
11 . The process of claim 9 , wherein:
each R independently is H or a C 1 to C 8 alkyl group;
R 1 and R 2 are linked to form a cycloalkyl ring or ring system or an aromatic ring or ring system; and
each X independently is Cl or Br.
12 . The process of claim 1 , wherein a weight ratio of the chemically-treated solid oxide to the alpha-diimine nickel halide complex is in a range from about 10:1 to about 200:1.
13 . The process of claim 1 , wherein:
the catalyst composition comprises the co-catalyst and
a weight ratio of the co-catalyst to the alpha-diimine nickel halide complex is in a range from about 5:1 to about 75:1.
14 . The process of claim 1 , wherein:
a weight ratio of the C 6 to C 27 propylene oligomers to the alpha-diimine nickel halide complex is in a range from about 100:1 to about 2500:1.
15 . The process of claim 1 , wherein:
the oligomer composition is produced at an oligomerization temperature in a range from about 10° C. to about 50° C.; and
the olefin feedstock contains at least about 50 wt. % of the C 6 to C 27 propylene oligomers.
16 . The process of claim 1 , wherein:
the oligomer composition is produced at an oligomerization temperature in a range from about 15° C. to about 35° C.; and
the olefin feedstock contains at least about 95 wt. % of the C 6 to C 27 propylene oligomers.
17 . The process of claim 1 , wherein the process further comprises a step of combining the oligomer composition with a heavy propylene oligomer comprising C 30 + propylene oligomers to form an oligomer blend composition.
18 . The process of claim 17 , wherein the oligomer blend composition comprises less than or equal to about 20 wt. % of the oligomer composition.
19 . The process of claim 17 , wherein the process further comprises a step of hydrogenating the oligomer blend composition to form a hydrogenated oligomer blend composition.
20 . The process of claim 19 , wherein the hydrogenated oligomer blend composition is characterized by:
a flash point in a range from about 140 to about 260° C.;
a viscosity index in a range from about 85 to about 130; and
a pour point in a range from about −10 to about −40° C.