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Pentane Transformation over Silicaalumina/BCl3 Solid Superacid

Marczewski M., Dębowiak M., Marczewska H.

Polish Journal of Chemistry

2003

Vol. 77 / nr 5

737-747

Pentane transformation over SiO2(87%) - Al2O3/BCl3 superacid was studied. It was found that Brönsted superacid centres formed in the reaction between the carrier and BCl3 vapours are active in n-pentane low temperature transformation. Pentane is converted over them into carbenium ion (through intermediate carbonium ion), which either undergoes isomerization to form 2-methylbutane or reacts with a second molecule of the reactant forming 2-methylpropane and a longer surface carbenium ion. The latter acts as a secondary active centre for 2-methylpropane formation and also undergoes further transformation leading finally to coke.

Morphology and activity of zirconia-sulfate aerogels

Mrowiec-Białoń J., Pająk L., Marczewski M., Lachowski A., Jarzębski A.

Polish Journal of Chemistry

1999

vol. 73 nr 5

805-811

Zirconia-sulfate aerogels obtained from the process with the molar hydrolysis ratio r=4 are more porous and active than those synthesized with r=2. Sulfate ions markedly hinder sintering of zirconia and structure consolidation during heat treatment and this process depends on their concentration. At a higher sulfate load (20 mol% of SO2-4 in Zro2) zirconia is amorphous upon calcinations at 773 K, irrespective of the water content in the synthesis, while at a lower load it can be crystalline. XRD analysis indicates that the crystalline phase of calcined zirconia-sulfate is cubic and not tetragonal, as observed in conventional zirconia, and reported in previous studies. Acid strength of ZrO2- SO2-4 system appears comparable to that of AlCl3/Al2O3, but lower than that of SbF5/Al2O3.

Bronstedd and Lewis solid superacids of carrier/metal halide type

Marczewski M., Marczewska H., Juszczyk W.

Polish Journal of Chemistry

1999

vol. 73 nr 3

509-518

Superacid properties of alumina, silica-alumina and silica exposed to TiCl4 and HfCl4 vapour have been studied and compared with previously obtained results for catalysts containing BF3, SbF3, AlCl3 and ZrCl4. It was found that the reaction of the vapour of metal halides of Lewis nature (MeXn) with oxides like alumina, silica-aluminas and silica results in the formation of the Bronsted superacid centers if acid strength of hypothetical acid MeXn×XH is higher than that of sulphuric one. The Lewis superacid centers are formed in the reaction of carrier containing alumina phase with metal halide of strong electron acceptor ability.

N-pentane isomerization in the presence of BCl3 containing superacids

Marczewski M., Dębowiak M., Przerwa K.

Polish Journal of Chemistry

1998

Vol. 72, nr 9

2115-2126

New superacid catalysts have been obtained by the action of BCl3 vapours on silicaalumina (87% SiO2). The mechanism and kinetics of pentane isomrerization is discussed.