LEV-zeotype magnesium aluminophosphates with variable Mg/Al ratios

Dalton Trans. 2012 Jun 14;41(22):6855-60. doi: 10.1039/c2dt12106a. Epub 2012 Mar 12.

Abstract

By using two different organic amines, n-methylpiperidine and 1,2-diaminocyclohexane (DACH), as the structure-directing agents (SDAs), two magnesium aluminophosphate molecular sieves |(C(6)H(14)N)(2)|[Mg(2)Al(7)(PO(4))(9)] and |(C(6)H(14)N(2))(1.4)(H(2)O)(2)H(2)|[Mg(2)Al(5)(PO(4))(7)], denoted as MgAPO-CJ67(a) and MgAPO-CJ67(b), have been synthesized under hydrothermal conditions. They are the first example of Mg incorporated aluminophosphates with the LEV-zeotype structure. The magnesium and aluminum atoms co-occupy the same crystallographic positions in the frameworks of MgAPO-CJ67(a) and MgAPO-CJ67(b), but with different Mg/Al ratios of 1 : 3.5 and 1 : 2.5, respectively. MgAPO-CJ67(a) exhibits higher thermal stability upon calcination than MgAPO-CJ67(b), and its framework keeps intact after the removal of occluded organic SDAs. The N(2) adsorption on the calcined MgAPO-CJ67(a) sample gives the BET surface area of 386 m(2) g(-1). NH(3)-temperature programmed desorption (NH(3)-TPD) analysis shows that MgAPO-CJ67(a) has a medium acidity.