Direct comparison among the formation of terephthalate- and carbonate-intercalated Mg-Al-LDH: The influence of the high aluminum content

First principles calculations based on Density Functional Theory (DFT) were used to investigate the standard thermodynamic potentials and also structural and electronic properties of terephthalate (TA) and carbonate intercalated Layered Double Hydroxides (LDH) with molar ratios, x = Al3+/Al3+ +Mg2+, equal to 0.25, 0.33 and 0.50. Herein we discuss how the interlayer species and formation of the LDH are influenced by the layer charge. Mg-Al-CO3 with high Al3+ content, x over 0.33, is hard to be obtained by synthetic methods in its pure phase, and LDH with high molar ratio is desirable for several applications such as intercalation reactions and obtainment of mixed oxides with better synergistic effects. This structure profile is easily to be acquired by the use of terephthalate as counterion than carbonate. The reason for this behaviour was found to be the competition among water molecules and anions for the interlayer sites. The dehydration process was simulated with excellent agreement with experimental data and showed important structural changes of TA in the interlayer space.