Doctor of Philosophy (PhD)
Double-bond isomerization of internal C16-C18 olefins is a necessary step in the production of paper sizing agents. In this work, the properties that enable long-lasting solid acid catalysts (both commercial and lab-synthesized) were identified, the efficacy of regenerated solid acid catalysts was tested, and the feasibility of organometallic chain-walking catalysts (both homogeneous and polymer-supported) for olefin isomerization was evaluated. Hexadecene isomerization was investigated using perfluorinated ion exchange resins (Nafion®) supported on SiO2 or Al2O3, sulfonated poly(styrene-co-divinylbenzene) resins (PS-DVBs), tungstated zirconias, and acidic zeolites. Selected catalysts underwent lifetime studies. Oversulfonated PS-DVBs (e.g., Amberlyst 35) were reasonably selective with long lifetimes, only gradually deactivating due to poisoning by surface oligomers. Amberlyst® 70, Amberlyst® XN1010, ZSM-35 and SAPO-11 were evaluated because of their lower acid site densities and degree of crosslinking (for the PS-DVBs). None of these catalysts were optimal for various reasons. Both beneficial and harmful effects arising from the cooperativity of acid sites in close proximity were observed. Enhanced acid strength was associated with multiple adjacent sites, but at the expense of more rapid deactivation due to olefin oligomerization. Used SAC-13 catalysts were regenerated by solvent extraction. Nonpolar m-xylene was the most effective in reopening pore volume. The catalysts regenerated by ethanol were active in octadecene isomerization, but deactivation was relatively rapid. Small pores volumes and a small fraction of surface sites resulted in both a diffusion limitation within the catalyst and enhanced deactivation from fewer oligomerization events. Homogeneous Fe(CO)5 was an extremely effective catalyst capable of highly selective double bond isomerization (100% selective) with a high (80%) conversion of alpha olefins to internal olefins. The optimal batch reactor conditions to isomerize 2 L of 1-hexadecene were 500 ppm of Fe(CO)5 at 180°C for 1-4 h. Iron pentacarbonyl was also immobilized on a functionalized PS-DVB. Iron carbonyls were detected on the surface, though it was unclear whether they were physisorbed or bonded to surface groups. The catalyzed reactions of octadecenes were slow with a very low conversion and internal olefins were being removed from the product. Therefore, the heterogeneous iron carbonyls synthesized here were ineffective for generating internal double bonds.
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Bruno, James Edward, "Catalysts for the Positional Isomerization of Internal, Long-Chain Olefins" (2015). LSU Doctoral Dissertations. 278.