Allylbenzene isomerisation over as-synthesized MgAl and NiAl containing LDHs: Basicity-activity relationships

摘要

Isomerisation of allylbenzene to β-methyl styrene (cis + trans) has been successfully carried out over Mg and Ni containing as-synthesized hydrotalcites (HTs). The samples screened by varying the M(Ⅱ)/Al atomic ratio showed that MgAl4-HT and NiAl4-HT (M(Ⅱ)/M(Ⅲ) atomic ratio is around 4.0) exhibited a maximum conversion of 99% and 95% respectively at 160 ℃ using DMF as solvent in 6 h. Studies were done to discern the surface basicity of these samples through CO_2 temperature programmed desorption and phenol adsorption. Both measurements gave reasonable correlation with isomerisation activity. This reaction can be studied as a model reaction for assessing basicity of as-synthesized HTs augmenting the earlier results of Aramendia et al. for calcined HTs (Aramendia, 2002, 2004).