Designed Synthesis of Mesoporous Solid-Supported Lewis Acid-Base Pairs and Their CO Adsorption Behaviors.

Conventional amines and phosphines, such as diethylenetriamine, diphenylpropylphosphine, triethylamine, and tetramethylpiperidine, were grafted or impregnated on the surface of metalated SBA-15 materials, such as Ti-, Al-, and Zr-SBA-15, to generate air-stable solid-supported Lewis acid-base pairs. The Lewis acidity of the metalated materials before and after the introduction of Lewis bases was verified by means of pyridine adsorption-Fourier transform infrared spectroscopy. Detailed characterization of the materials was achieved by solid-state C and P MAS NMR spectroscopy, low-temperature N physisorption, X-ray photoelectron spectroscopy, and energy-dispersive X-ray mapping analyses. Study of their potential interactions with CO was performed using CO adsorption isotherm experiments, which provided new insights into their applicability as solid CO adsorbents. A correlation between solid-supported Lewis acid-base pair strength and the resulting affinity to CO is discussed based on the calculation of isosteric enthalpy of adsorption.