Boron-containing catalysts active and selective for isobutene production

R. A. COMELLI

Cancún, México

Simposio; XVII IMRC - International Materias Research Congress, Symposium on New Catalytic Materials, Symposium 22; 2008

Academia Mejicana de Ciencia de Materiales

Potassium ferrierite (K-FER) and alumina (Al) are inactive materials for the linear butene skeletal isomerization. By impregnating boron species on both materials, catalytic activity in that reaction was promoted. Catalysts were prepared by wet impregnation, using boric acid as boron precursor. The linear butene reaction was measured at 450ºC, atmospheric pressure, and 0.10 atm 1-butene partial pressure. Both catalysts display similar catalytic performances. Butene conversion reaches 25-28%, being the isobutene selectivity 81-90%, and the isobutene yield 22-25%. The isobutene yield is higher than two times the corresponding one obtained with the acid ferrierite (H-FER); the isobutene selectivity is also significantly higher than the H-FER’s one. Then, boron species impregnated on both potassium ferrierite and alumina generate and/or promote active sites having the adequate acidity to produce isobutene without favoring undesirable side reactions. The main by-products are propene and pentenes, appearing only small differences between both catalysts. Porous structure influences both by-product distribution and formation of carbonaceous deposits. Another characteristic of these catalysts is their high stability reached, because of they remain active and selective after 24 h under reaction conditions. This behavior is quite different to the characteristic one of H-FER which display a conversion decrease and a selectivity increase after some minutes-on-reaction. In this way, the carbonaceous deposit formed on B-K-FER is only 0.9% after 24 h-on-stream meanwhile it reaches 7-8% on H-FER after 30 min under reaction conditions. Regeneration of B-K-FER and B-Al is possible, displaying activity after 200 h-on-stream. Boron species impregnated on potassium ferrierite and alumina are responsible of the catalytic activity in the isobutene production.