Preparation of an olefin oligomerization catalyst

A process for trimerizing an olefin in the presence of a catalyst system:

• the catalyst system comprising;
• 1) a chromium(III) C3-C25 carboxylate composition that is
• i) characterized as having a KBr pellet infrared spectrum with a υasym (CO2) peak infrared absorbance peak within 110 cm−1 of the υsym (CO2) infrared absorbance peak and having an infrared absorbance peak height ratio of a υasym (CO2) infrared absorbance peak at 1516±15 cm−1 to infrared absorbance peak located at 700±50 cm−1 greater than or equal to 3:1,
• ii) characterized as having a goodness of fit test value, R2, of at least 0.6 when comparing high-energy X-ray diffraction g(r) data points of the chromium(III) C3-C25 carboxylate composition to calculated high energy X-ray diffraction g(r) data points of a theoretical model of mononuclear chromium(III) acetate over an r range from 1.3 Angstroms to 4 Angstroms, wherein atomic coordinates of the theoretical model of mononuclear chromium(III) acetate have been optimized to the following values
• Atom
• X
• Y
• Z
• Cr
• 0
• 0
• 0
• C1
• 1.843475
• −0.40852
• −1.43058
• O1
• 0.738585
• −1.038881
• −1.567619
• O2
• 1.90289
• 0.461636
• −0.494039
• C2
• 3.026757
• −0.697968
• −2.303537
• H1
• 3.586188
• 0.221029
• −2.49448
• H2
• 2.70492
• −1.158746
• −3.239287
• H3
• 3.689716
• −1.395002
• −1.777323
• O3
• −0.772555
• 1.631901
• −0.909192
• O4
• −0.481341
• 1.511899
• 1.249048
• C4
• −1.400219
• 3.584765
• 0.389991
• C3
• −0.872192
• 2.190556
• 0.236797
• H4
• −1.932477
• 3.891686
• −0.511821
• H5
• −2.054935
• 3.640368
• 1.263653
• H6
• −0.55862
• 4.266381
• 0.559197
• O5
• 0.288007
• −1.521043
• 1.29563
• O6
• −1.664703
• −1.059059
• 0.43961
• C5
• −0.959016
• −1.79628
• 1.210803
• C6
• −1.568434
• −2.912588
• 2.003767
• H7
• −2.492313
• −3.252317
• 1.531746
• H8
• −1.803373
• −2.543365
• 3.009177
• H9
• −0.856348
• −3.735188
• 2.10.2561
• and wherein R2=1−(SSerr/SStot) where Serr is a calculated high energy X-ray diffraction g(r) data points for a theoretical model of the mononuclear chromium carboxylate and Stot is a summation of the squares of the differences between a high energy X-ray diffraction g(r) data points of the chromium carboxylate composition and a mean of the high energy X-ray diffraction g(r) data points of the chromium carboxylate composition, or
• iii) produced by a process comprising
• contacting under substantially anhydrous and substantially acid-free conditions
• (1) a chromium(III) precursor having a formula CrX3Llwhere each X independently is a halide, each L independently is a C2-C10 ether, a C2-C10 thioether, a C2-C5 nitrile, a C1-C30 amine, or a C3-C30phosphine, or any combination thereof, and l ranges from 0 to 7,
• (2) a Group 1 or Group 2 metal C3-C25 carboxylate, and
• (3) a first solvent,
• wherein the chromium(III) C3-C25 carboxylate composition produced by the process has a KBr pellet infrared spectrum having a υasym (CO2) infrared absorbance peak at 1516±15 cm−1 and the υasym (CO2) infrared absorbance peak is within 110 cm−1 of the υsym (CO2) infrared peak;
• 2) a pyrrole compound;
• and
• 3) a metal hydrocarbyl compound;
• and
• the process comprising contacting an olefin comprising ethylene, the chromium(III) C3-C25 carboxylate composition, the pyrrole compound, and the metal hydrocarbyl compound to produce a trimerization product.