Preferential oligomerization of isobutene in a mixture of isobutene and 1-butene over sodium-modified 12-tungstosilicic acid supported on silica

✍ Scribed by Jin Zhang; Mitsuru Kanno; Jiao Zhang; Ryuichiro Ohnishi; Kakeru Toriyabe; Hiromi Matsuhashi; Yuichi Kamiya

• Book ID: 103835231
• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 336 KB
• Volume: 326
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/j.molcata.2010.04.017

✦ Synopsis

Modification of 15 wt% H 4 SiW 12 O 40 /SiO 2 with Na + ions was investigated. Na-modified H 4 SiW 12 O 40 /SiO 2 showed higher selectivity for isobutene oligomerization in the preferential oligomerization of isobutene in an equimolar mixture of isobutene and 1-butene than the unmodified one and the selectivity increased with an increase in the Na + ion content. The highest selectivity (∼97%) was achieved by using Na 3 HSiW 12 O 40 /SiO 2 . The activity decreased with an increase in the Na + ion content. Unmodified H 4 SiW 12 O 40 /SiO 2 had two kinds of acid sites with different acid strengths (medium and strong acid sites) on the outermost surface as revealed by temperature-programmed desorption of benzonitrile. However, the strong acid sites were eliminated by modification with alkaline metal cations; for example, Na 3 HSiW 12 O 40 /SiO 2 had a negligible amount of strong acid sites. Thus, we concluded that the absence of strong acid sites on the outermost surface is the reason for the high selectivity. Li 3 HSiW 12 O 40 /SiO 2 and K 3 HSiW 12 O 40 /SiO 2 also exhibited high selectivity for isobutene oligomerization with activities comparable to that of Na 3 HSiW 12 O 40 /SiO 2 .