Olivier-Bourbigou, H; Chodorge, JA; Travers, P
Homogeneous catalysis entered a new era with the recent discovery of the excellent activities and selectivities of tailor-made metallocene complexes associated with alkylaluminoxanes for light olefin polymerization reactions. Although it is generally poorly represented in the refining industry, it is used mainly in the production of large-scale chemical intermediates and in fine chemicals. Three homogeneous catalytic processes have attained commercial operation, cyclohexane, Dimersol and Alphabutol, and recently, two new processes, AlphaSelect and Difasol were announced. Since 1979, cyclohexane process has accounted for over 80% of new benzene hydrogenation capacity put on stream throughout the world. In 1981, the selective dimerization of ethylene, the Alphabutol process, to produce 1-butene, which is currently the most popular key ethylene co-monomer for manufacturing of linear low-density polyethylene (LLPDE), was launched using soluble titanium-triethylaluminum complex. Today, 20 Alphabutol units were licensed having a combined 1-butene capacity of 330,000 ton/yr and almost 50% of the world's 1-butene incorporated as co-monomer in LLPDE. The Dimersol technology, the dimerization and oligomerization of light olefins, is now used in three different processes, Dimersol-E, Dimersol-G, and Dimersol-X. These processes offer an attractive means to upgrade light olefins in addition to gasoline or ethylene and propylene and still satisfy the market requirements of motor fuels or petrochemicals. The catalyst system results from the reaction, in dilute medium, of two components: a catalyst precursor mixture containing a nickel salt and an aluminum-based co- catalyst. At present, 35 Dimersol units were licensed corresponding to an overall processing capacity of over 4.5 million ton/yr of feed and more than 25 of these units are now in operation to produce octane booster additives for gasoline with a total processing capacity of 3.4 million ton/yr. The commercial success of the Alphabutol process and the demand for new grades of polyethylene prompted the development of a new process, the AlphaSelect process, to produce linear α-olefins by ethylene oligomerization. This process maximizes C4-C10 α-olefins using the Alphabutol technology. The use of Difasol technology extends the field of application of the Dimersol-X process, which produces octenes by butenes dimerization, to less reactive feeds such as C5 olefins, allowing for the production of nonenes and decenes through co-dimerization of C4 and C5 olefins.