Oligomerization of Ethylene SHOP Process

Long-chain a-olefins are of major industrial importance in the production of detergents, plasticizers, and lubricants. Today such a-olefins are mainly produced by oligomerization of ethylene (Eq. 3-9). Numerous homogeneous transition metal catalyst on the basis of Co, Ti, and Ni have been described for this reaction. 

The nickel-catalyzed Shell higher olefin process (SHOP) is of major industrial importance [9,11]. Ethylene is converted to a-olefins with a statistical distribution in which the lower oligomers are favored (so-called Schulz Flory distribution). This is carried out at 80-120 °C and 70 140 bar in the presence of a nickel catalyst with phosphine ligands such as Ph2PCH2COOK. The product mixture is separated into C4 io, C12-18, and C20+ fractions by distillation. 

The C12-18 fraction contains a-olefins with the desired chain length for the detergent industry. The top and bottom olefins are subjected to a combination of doublebond isomerization and metathesis. Isomerization gives a mixture of inner olefins with a statistical distribntion of the double bond, metathesis of which gives a new mixture of iimer olefins from which the Cio-14 olfins can be separated by distillation. The process is depicted schematically in Equation 3-10. 

however, the inner olefins are cleaved with ethylene over heterogeneous catalysts (e. g., Re207/Sn(CH3)4/Al203), a mixture of unbranched terminal olefins is ob- 

The combination of isomerization and metathesis with distillation and recycling offers a unique technology for obtaining a desired carbon-number distribution [7]. 

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