Synthesis and characterization of a novel boron-containing aluminium basic chloride

Abstract

A novel boron-containing aluminium basic chloride [B-C(1)] has been hydrothermally synthesized in the system B₂O₃–Al₂O₃–M_xO–H₂O (M = Li, Na, K, Mg, Ca, Ba; x= 1 or 2) and characterized by X-ray diffraction (XRD), inductive coupled plasma-analysis (ICP), scanning electron microscopy (SEM), infrared spectroscopy (IR), magicangle spinning nuclear magnetic resonance spectroscopy (MASNMR) and thermal analysis techniques. There are significant effects due to pH, temperature and type of ion in the reaction mixture on the crystallization products. Chemical analysis shows that B-C(1) has a composition of B_0.15Al_9.85O₉(OH)₁₀Cl₂. The crystal is indexable on an orthorhombic unit cell with a= 19.27 Å, b= 14.80 Å, and c= 8.55 Å. B-C(1) may undergo thermal transformation sequences involving γ-, δ-, θ-, and α-aluminas at different temperatures. IR spectroscopy and temperature-programmed desorption of NH₃(NH₃-TPD) reveals that there are predominantly Lewis acid sites of medium strength on the surface of B-C(1). It can be shown that B-C(1) is an excellent catalyst for the selective synthesis of but-2-ene from ethanol.