OLIGOMERIZATION OF BUTENES 248

2-Butenes (after separation of l-butene) can be oligomerized in the liquid phase on a heterogeneous catalyst system to yield mainly C₈ and C_l2 olefins. The reaction is exothermic, and requires a multitubular carbon steel reactor. The exothermic heat is absorbed by water circulating around the reactor shell. Either a single- or a two-stage system is used.

The process can be made to produce either more linear or more branched oligomers. Linear oligomers are used to produce nonyl alcohols for plasticizers, alkyl phenols for surfactants, and tridecyl alcohols for detergent intermediates. Branched oligomers are valuable gasoline components. Figure 1.1 shows the Octol oligomerization process.

Figure 1.1. The Octol Oligomerization process for producing C₈’s and C₁₂’s and C₁₆’s olefins from n-butenes: (1) multitubular reactor, (2) debutanizer column, (3) fractionation tower.

A typical analysis of A-type oligomers (branched) is shown in Table 1.1.

Table 1.1: Typical analysis of branched oligomers (Type A)