Skeletal Isomerization ofn-Butene

Shape Selectivity of HFER Zeolites as Responsible for the Positive Effect of Their Si/Al Ratio on the Selectivity to n-Butene Isomerization into Isobutene

“…However, the positive effect that the HFER Si/Al ratio [10,19,20] and the decrease in n-butene pressure [10,13,21,22] have on the selectivity to isobutene of fresh HFER is in favour of this proposal. Indeed, it could be expected that the rate of bimolecular reactions is more affected than that of monomolecular reactions by a decrease in acid site density or in n-butene pressure.…”

“…Thus, the higher the n-butene pressure the greater the number of successive reactions undergone by n-butene molecules along a 10-MR channel hence, the lower the selectivity to isobutene as shown by several authors [10,13,21,22]. Furthermore, the smaller the crystallite size hence the smaller the length of the 10-MR channels, the higher the selectivity to isobutene.…”

New insights into the reaction mechanism and the rate-determining step of n-butane hydroisomerisation over reduced MoO3 catalystsElectronic supplementary information (ESI) available: experimental details. See http://www.rsc.org/suppdata/cc/b3/b304978g/

“…A schematic representation of the various equilibria and the rate-determining step taking place over the reduced MoO 3 at steady-state conditions is given below (see Scheme 1). The addition (as a mechanical mixture or as a support) of selective butene isomerisation catalysts such as the zeolite FER or CoAPO-11 14 could lead to much increased reaction rates. This possibility is currently under investigation.…”

Tungsten catalysts supported on activated carbonI. Preparation and characterization after their heat treatments in inert atmosphere

“…The acid surface properties of these catalysts are of major importance to determine their catalytic behavior (67). The acidic character of the tungsten oxide is well known (68,69), and its acid strength is the highest among the metal oxides from groups 4, 5, and 6 of the Periodic Table and (68). Two types of acid sites are found on the surface of (69) and these are quite important in reactions such as catalytic cracking and in the skeletal isomerization of 1-butene to isobutene (67).…”

“…The acidic character of the tungsten oxide is well known (68,69), and its acid strength is the highest among the metal oxides from groups 4, 5, and 6 of the Periodic Table and (68). Two types of acid sites are found on the surface of (69) and these are quite important in reactions such as catalytic cracking and in the skeletal isomerization of 1-butene to isobutene (67). In general, it is accepted that NH 3 is an excellent molecular probe to measure the total surface acidity of catalysts, since due to its strong basicity and small molecular size, it allows the measurement of acid surface sites inside narrow pores (71)(72)(73)(74)(75).…”