Boronation and galliation of zeolites β in an alkaline medium

Zeolite β (with a Si/Al ratio of 15.20) was boronated or galliated in an alkaline solution containing boron or gallium species. The boronated or galliated samples were characterized by XRD, FTIR, MAS NMR and N2 sorption measurement and the process for boronation/galliation was understood upon the characterization. By comparing with the alumination process, a difference between boronation/galliation and alumination was shown, i.e., boron or gallium atoms insert into the framework with more difficulty than aluminum atoms, resulting in a limited degree of introduction of the heteroatoms and a modification of the porous property of zeolite under the conditions similar to those for alumination. In combination with the deformability of beta framework, the state and the stability of boron atom in the framework were also discussed. The poor stability of boron or gallium atom in the framework and their unsuitable atomic sizes should be responsible for the low level of boronation or galliation.