Study On Novel Cocatalysts And Ligand For Ethylene Tetramerization

Liner a-olefin(LAO) is a very important raw material and widely used in many fields. There are many production methods in which the ethylene oligomerization method is the most important way to produce LAO, and its production accounts for 94.1% of the total.There is no application of ethylene oligomerization in our country. Comonomers such as 1-octene and 1-decene almost completely depend on importing. Because these importation is very expensive and most industries couldn't sustain, the development of the catalysts and techniques of synthesis 1-octene by ethylene tetramerization with patented right seems especially important and urgent. Since Cr(III)/PNP/MAO ternary catalytic system was firstly used in ethylene tetramerization reported by the Sasol, synthesis of 1-octene by ethylene tetramerization has become a hot spot of academic research, and the development of new catalytic system has made new progress.In this study, through the reaction of alkyl aluminum respectively and polyols, carboxylic acids, water, three types(seven kinds in total) of novel cocatalyst and mixed cocatalysts were synthesized. In addition, we has synthesized a new trinuclear structure of bisphosphonate amine (PNP) ligand.In the Cr(â…¢)/PNP/new cocatalysts ethylene tetramerization catalyst system, we investigated the influences of different Al/Cr mole ratio on catalytic activity and 1-octene selectivity,and the catalytst system was compared with that of AlEt3 and Al(i-Bu)3 as cocatalys.Also the influences of the Cr(â…¢)/new trinuclear structure of bisphosphonate amine(PNP) ligand/MAO cocatalyst system on catalytic activity and 1-octene selectivity were studied. We can got conclusion:when the acids and alcohols cocatalyst catalyzed the reaction of ethylene tetramerization, catalytic activities were lower than that with AlEt3 and Al(i-Bu)3 as cocatalyst, while the 1-octene selectivities were the opposite, among the rest, the performances of glycerol-based cocatalyst and oxalic acid-based cocatalyst were optimal.When the water-based cocatalyst catalyzed the reaction of ethylene tetramerization, catalytic activity and 1-octene selectivity of water-based cocatalyst were higher than that with AlEt3 and Al(i-Bu)3 as cocatalyst. After water (free water, crystal water) and alkyl aluminum (AlEt3,Al(i-Bu)3) synthesized cocatalysts, the influences of different aluminum/water molar ratio on catalytic activity and 1-octene selectivity were investigated, finaly the best aluminum/water molar ratio was determined.The cocatalyst that the best aluminum (triethyl aluminum)/water (crystal water) molar ratio catalyzed the reaction of ethylene tetramerization, catalytic activity and 1-octene selectivity were higher than that with cocatalysts which free water respectively AlEt3 and Al(i-Bu)3 reacted. When new trinuclear structure of bisphosphonate amine(PNP) ligand was used in the reaction of ethylene tetramerization, the catalytic activity is high under the lower Al/Cr molar.Through the mixing of EAO and MAO experiment, we could draw a conclusion:when the mixure of MAO and 30% of EAO as cocatalyst catalyzed the reaction of ethylene tetramerization, the catalytic activity and 1-octene selectivity still were high.