SKELETAL ISOMERIZATION OF 1-BUTENE ON SYNTHETIC CLINOPTILOLITE ZEOLITE

A pure, highly crystalline clinoptilolite (CLI) zeolite with a Si/Al r atio of 5.8 has been synthesized using a small amount (1%) of seed cry stals and tested as a catalyst for the skeletal isomerization of I-but ene at 623-723 K at atmospheric pressure. The catalytic results are co mpared to those obtained from a ferrierite (FER) zeolite with a Si/Al ratio of 7.6. It is found that selectivity for isobutene is very high on CLI zeolite, but conversion was lower than for FER zeolite. The sim ulated distribution and calculated potential profile of I-butene molec ules in CLI zeolite pore 10-ring channels show that the spatial constr aints imposed by the pores are very severe. The exceptional selectivit y and the low conversion of CLI zeolite results from the strict restri ction of adsorption to very specific sites, inhibiting dimerization, a s well as from the high potential barrier which reduces mass transfer.