Amine-functionalized fumed silica for CO2 capture through particle molecular layer deposition

[Display omitted] •Molecular Layer Deposition synthesizes amine adsorbents for CO2 capture.•Adsorption capacity increased with increasing MLD cycle numbers.•MLD adsorbents demonstrate highly active surfaces and robust regeneration.•First demonstration of tri-functional amine precursor used for MLD. Solid adsorbent materials for CO2 capture have received increasing attention due to the high regenerative energy requirements and physical limitations of traditional liquid systems. Supported amines have become widely-researched materials due to their ambient adsorption capabilities and low regeneration temperatures. Here, Particle Molecular Layer Deposition (MLD) is introduced as a novel loading method for amine functionalization to improve the regeneration stability and adsorption capacity of supported amine sorbents. This paper confirms two MLD chemistries: (3-aminopropyl)triethoxysilane (APTES) and N1-(3-trimethoxysilylpropyl)diethylene triamine (TMPTA). Both precursors were deposited at 150 °C in a binary reaction with water. Adsorption capacity of the amine functional groups increased to ~0.005 mmol/m2 as the number of MLD cycles increased. Low sorbent regeneration temperatures and stable regeneration of active sites over 25 cycles were demonstrated by both the APTES and TMPTA functionalized sorbent. This is the first demonstration of an MLD process used to functionalize a sorbent for CO2 capture. This is also the first use of TMPTA for MLD.