Mesoporous Organosilica with Amidoxime Groups for CO₂ Sorption

Abstract

Incorporation of basic species such as amine-containing groups into porous materials is a well-established strategy for achieving high uptake of acidic molecules such as CO₂. This work reports a successful use of the aforementioned strategy for the development of ordered mesoporous organosilica (OMO) with amidoxime groups for CO₂ sorption. These materials were prepared by two-step process involving: (1) synthesis of OMO with cyanopropyl groups by co-condensation of (3-cyanopropyl)­triethoxysilane and tetraethylorthosilicate in the presence of Pluronic P123 triblock copolymer under acidic conditions, and (2) conversion of cyanopropyl groups into amidoxime upon treatment with hydroxylamine hydrochloride under suitable conditions. The resulting series of amidoxime-containing OMO was prepared and used for CO₂ sorption at low (25 °C) and elevated (60, 120 °C) temperatures. These sorbents exhibited relatively high adsorption capacity at ambient conditions (25 °C, 1 atm) and remarkable high sorption uptake (∼3 mmol/g) at 60 and 120 °C. This high CO₂ uptake at elevated temperatures by amidoxime-containing OMO sorbent makes it a noticeable material for CO₂ capture