A chromium precursor for the Phillips ethylene trimerization catalyst: (2-ethylhexanoate)₂CrOH

Abstract

The conventional Phillips ethylene trimerization catalyst prepared by reacting Cr(EH)3 (EH = 2-ethylhexanoate), 2,5-dimethylpyrrole (Me2C4H2NH), Et3Al, and Et2AlCl in an aromatic hydrocarbon solvent was improved to obtain a congener composed of a new chromium precursor (EH)2CrOH, (Me2C4H2N)AlEt2, and Et3Al·ClAlEt2. Reaction of CrCl3 with 3 equiv. Na(EH) in water did not generate Cr(EH)3, but unexpectedly produced (EH)2CrOH. In comparison with the erratic catalytic performance of the original Phillips system, due to the ill-defined nature of the Cr(EH)3 source (16 or 6.8 × 10(6) g per mol-Cr h depending on the source), the improved system exhibited consistently high activity (54 × 10(6) g per mol-Cr h). Reaction of (EH)2CrOH with (Me2C4H2N)AlMe2·OEt2 afforded the dimeric Cr(II)-complex (6) coordinated by (η(5)-Me2C4H2N)AlMe2(NC4H2Me2) and μ2-κ(1):η(2)-Me2C4H2N ligands. 6 provided highly active species when activated with Et3Al·ClAlEt2.

Extremely Active Ethylene Tetramerization Catalyst Avoiding the Use of Methylaluminoxane: [iPrN{P(C6H4‐p‐SiR3)2}2CrCl2]+[B(C6F5)4]−

“…[8] The activity attained is also more than 4 times higher than the commercially used Chevron Phillips trimerization catalyst (1 000 Kg/g-Cr/h). [13] 4 ] À further supported that the bulky R 3 Si-substituents are crucial not only to achieve extremely high activity but also to minimize the generation of the problematic side product PE. X-ray crystallographic studies revealed that the prepared [(PNP)-CrCl 2 ] + [B (C 6 F 5 ) 4 ] À species existed as a dinuclear Cr III complex sharing the chloride ligand and coordinated by an additional CH 3 CN donor.…”

“…Ethylene was purified by contact with molecular sieves and copper for more than 12 h under 48 bar pressure. 1 H NMR (600 MHz), 13 C NMR (150 MHz), and 31 P NMR (243 MHz) spectra were recorded using a JEOL ECZ 600 spectrometer. Continuous wave X-band EPR spectra were collected at 5 K on a Bruker EMX plus 6/1 spectrometer with the experimental parameters of 1 mW microwave power, 10 G modulation amplitude, and 5 scans at KBSI Western Seoul Center Korea.…”

“…[8][9][10] Phillips discovered the ethylene trimerization catalyst in the early 1990s, which was commercialized in the early 2000s. [11][12][13] Another type of Cr-based catalytic system that generates 1-octene as the main product was also discovered at Sasol in the early 2000s. [14] While the Phillips trimerization catalyst is constructed with (2-ethylhexanoate) 3 Cr (III), 2,5-dimethylpyrrole, and inexpensive Et 3 Al·ClAlEt 2 working at a high temperature above 90°C, the original Sasol tetramerization catalyst is composed of Cr(acac) 3 , iPrN(PPh 2 ) 2 (abbreviated as PNP ligand), and expensive modified-methylaluminoxane (MMAO), which works best at a relatively low temperature of 60°C.…”

Exploring Basic Components Effect on the Catalytic Efficiency of Chevron-Phillips Catalyst in Ethylene Trimerization

“…Typically, ethylene oligomerization is conducted in a solvent media at both industrial and laboratory scales, using the Chevron-Phillips catalytic system. Typical oligomerization solvents employed in both academic laboratories and industrial settings are either toluene or some saturated alkanes, such as methylcyclohexane [24][25][26]. For this reason, the effect on the catalytic cycle of the two most widely used solvents, methylcyclohexane and toluene, was studied.…”

Exploring Basic Components Effect on the Catalytic Efficiency of Chevron-Phillips Catalyst in Ethylene Trimerization

“…saturated alkanes such as methylcyclohexane [24,25,26]. For this reason, the effect of two 280 most widely used solvents, methylcyclohexane and toluene, on the catalytic cycle was 281 studied.…”