24-P-20-The use of ITQ-7 as catalyst for alkylation of isobutane with 2-butene

This chapter describes the usage of ITQ-7 as catalyst for the alkylation of isobutane with 2- butane. The catalytic behavior of aluminium (Al)-ITQ-7 zeolite, with a three-dimensional system of large pore channels, has been evaluated for the liquid phase alkylation of isobutane with 2-butene and compared to that of a Beta zeolite. In absence of deactivation, zeolite ITQ-7 gives a higher proportion of C5-C7/C5+, obtained by the cracking of C8, especially of the bulky C9+. However, the main differences are observed in the distribution of the trimethylpentane (TMP) isomers. Although zeolite ITQ-7 is more selective to TMP in the C8 fraction than Beta, the most abundant isomers are 2,3,3- and 2,3,4-TMP instead of the primary 2,2,3-TMP or the thermodynamically favored 2,2,4-TMP. This is a clear shape selectivity effect due to the smaller pore size of ITQ-7 as compared to Beta, and the fact that 2,3,3- and 2,3,4-TMP are the isomers with less restricted transition states and smaller diffusion problems.