Synthesis And Application Explore New Ethylene Oligomerization Catalyst

In the catalytic system of ethylene selective oligomerization, Chromium catalysts are currently widespread concerned research emphasis due to their high activity and selectivity characteristics for preparation of 1-octene by ethylene tetramerization. In such field, the breakthrough processes are currently focused on the following two directions. One is to change the structure and electron donor of diphosphinoamine ligand, in order to give the main catalyst and Cr(III) a better coordination environment to enhance the activity of the catalyst system and selectivity of product; Second is to investigate the effects of various promoters on the catalytic system, in order to find promoters with low-cost and good effect in place of expensive methylaluminoxane(MAO) to promote industrial production.In the study of this issue, linear organic amines, organic amines with benzene and pyridine compounds reacted with diphenyl phosphorus trichloride respectively. As a result, we synthesized six new diphosphinoamine ligands for ethylene oligomeriztion. The structures of the ligands are determined by 1HNMR and IR spectroscopy. According to the polymerization mechanism of the ethylene tetramerization, the catalytic system in composed of corresponding ligand, promoter and Cr(III) has been studied in order to select the catalyst with best performance. According to the polymerization mechanism of the ethylene tetramerization, the catalytic system in composed of corresponding ligand, promoter and Cr(III) has been studied in order to select the catalyst with best performance. Also, we investigated effects of the reaction conditions on the activity of the catalytic system and product selectivity of oligomerization, and determined the best process conditions.Oligomerization product are specifically analyzed through gas chromatography/mass spectrometry.The results showed that: Under the condition of the reaction temperature is 55℃, Al/Cr was 300:1, ligand 1/Cr was 1.5:1 and the polymerization pressure is 3.0MPa, in catalytic system in composition of the new diphosphinoamine(PNP) ligand 1, Cr(III) and methylaluminoxane(MAO), the catalyst activity is up to 5.45×106gPE/(mol Cr·h), the selectivity of 1-octene is up to 61.29% and the total selectivity of 1-hexene and 1-octene is up to 64.92%.