No abstract

Isobutene dimerization is an important route to properly utilize mixed C 4 and further produce isooctane with a high-octane number to replace MTBE in gasoline. A highly selective catalyst, which is effective for isobutene dimerization but ineffective for other olefins in the C 4 mixture, is necessary for industrial implementation. In this work, a series of supported metal sulfate catalysts Fe x Zn y /SiO 2 were prepared and characterized by XRD, SEM, N 2 physical adsorption-desorption, NH 3 -TPD, Py-FTIR, and XPS. Fe 0.2 Zn 1.8 /SiO 2 can achieve isobutene conversion up to 89 % with 0 % conversion of n-butene, and the selectivity of isooctenes (C 8 = ) product is 57 % (10 h on stream). Furthermore, isobutene conversion can sustain above 80 % after 50 h. It is found that these supported catalysts contain Zn 2 + , Zn + , Fe 3 + , and Fe 2 + species, and there is a synergetic effect between Zn 2 + and Fe 2 + . Zn 2 + is beneficial to improve the conversion of isobutene, and Fe 2 + facilitates the formation of C 8 = , resulting in a high C 8 = yield.