Sorption of n-butylamine by dodecatungstosilicic acid

Sorption of n-butylamine by dehydrated crystalline H4SiW12O40 (SiW) was stu died by sorption from vapour phase, thermometric titration, FTIR as well as C-13 NMR spectroscopy. It has been shown that in the first stage rapid sor ption occurs resulting in the formation of protonated n-butylamine C4H9NH3. In the second stage the kinetics of sorption is governed by the diffusion equation (D=1.3(10(-14) cm(2)s(-1)). Also, in the sorption of n-butylamine from the solution in toluene, two distinct stages were observed: the initi al one was characterized by sorption heat of 102.8 +/- 1.7 kJ/mol H+ and in the subsequent stage it decreased to 30-40 kJ/mol H+ It has been concluded that the former one corresponds to the formation of C4H9NH3+ cation and th e latter one is the heat of addition of further n-butylamine to C4H9NH3+ mo nomer thus forming larger protonated clusters.