Development of Clean Catalyst for Alkylation of Isobutane with 2-butene PDF Download

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Book Description
The alkylation of isobutane with light olefins is a reaction of considerable interest and plays an important role in the petroleum industry, since it produces branched C 8 paraffins that inherently possess higher octane number. However, current processes with HF and H 2 SO 4 have been limited due to their toxic nature. For this reason, the replacement of these catalysts with clean catalyst is favorable. One of clean catalysts, ZSM-12 zeolite was prepared using TEA + as organic template. Among the various parameters that affect the crystallization of ZSM-12, aluminum content of the gel, OH-/SiO 2 and TEA + /SiO 2 ratios were the important determinants. Aluminum rich ZSM-12 with Si/Al ratio of 30 was successfully synthesized. Alkylation of isobutane with 2-butene was carried out over large pore zeolites with various pore structures. Under identical reaction conditions, Beta and ZSM-12 were shown to outperform other zeolites. This higher stability is believed to be a result of their specific pore architecture. For the selectivity toward the individual TMP and DMH compounds, pore architecture also plays a significant role in determining these selectivities. The influence of Si/Al ratios has been studied using directly synthesized beta zeolites. The zeolites prepared possess comparable structural properties but differ in acid site density. In contrast to the common belief that a higher aluminum content zeolite is more stable, optimum Si/Al ratios of beta was observed. This unpredicted result could be attributed to the existence of an optimal level of acidity, which minimizes the formation of coking materials. The deactivation pathway of one-dimensional zeolites, namely LTL and ZSM-12, has been investigated. During the reaction, both zeolites displayed different product distribution with loss of catalytic activity. The results supported the fact that LTL deactivated mainly by pore blockage but ZSM-12 deactivated due to site coverage. A study of the alkylation in ionic liquid has been conducted using in 1-alkyl-3-methylimidazolium halides-aluminum chloride encompassing various alkyl-group (butyl-, hexyl- and octyl- ) and halides (Cl, Br and I) on its cation and anion, respectively. Among the ionic liquids, [C 8 mim]Br-AlCl 3 showed outstanding catalytic performance, due to the higher inherent acidity and solubility relative to others.