Robust Immobilized Amine CO₂ Sorbent Pellets Utilizing a Poly(Chloroprene) Polymer Binder and Fly Ash Additive

Abstract

Pelletization of ca. 50 wt % amine/silica carbon dioxide sorbents was achieved with the novel combination of fly ash (FA) as a strength additive and hydrophobic poly(chloroprene) (PC) as a binder. The PC content and overall synthesis procedure of these materials were optimized to produce pellets, labeled as FA/E100‐S_(20/80)_12.2, with the highest ball‐mill attrition resistance (<0.5 wt % by fines, 24 h) and maximum CO2 capture capacity of 1.78 mmol CO2 g−1. The strength of the pellets was attributed to hydrogen‐bonding of the relatively homogeneous PC network with the interlocked FA and BIAS particles (DRIFTS, SEM‐EDS). The low degradation of 3–4 % in the pellet's CO2 capture capacity under both dry TGA (7.5 h) and practical fixed‐bed (6.5 h dry; 4.5 h humid,≈5 vol % H2O) CO2 adsorption–desorption conditions highlights the pellet's excellent cyclic stability. These robust pellet characteristics make PC/FA/sorbent materials promising for commercial scale, point‐source CO2 capture.

Steam-Stable Basic Immobilized Amine Sorbent Pellets for CO2 Capture Under Practical Conditions

“…Pelletized BIAS for CO 2 capture were prepared by 2 methods. Method (ii-a) involved pelletization of amine-functionalized silica particles using our previously reported method, , whereby a 50 wt % E100/SiO 2 particle sorbent (E100-S) was first prepared and then bound together with a PC latex polymer binder. E100-S was synthesized by first dissolving 5.0 g of E100 in 100.0 g of MeOH and mixing the resulting impregnation solution with 5.0 g of amorphous silica (CS 2129, D avg.…”

“…Attrition testing of the pellets via our previously reported ball mill method was conducted in parallel to crush testing for further examination of the pellets’ mechanical properties under dynamic conditions. Briefly, 2.0 g of pellets and 5.2 g of 3/16″ stainless steel ball bearings were placed into a 230 mL glass jar ( D = 7 cm, L = 9 cm) equipped with a baffle.…”

“…The inherently reduced surface area/volume ratio of the larger pellets could moderate thermal and oxidative sorbent degradation of the sorbent by limiting its contact with heated desorber walls. While the bulk of BIAS-related literature focused on particle sorbents, a collection of pellet-based works was produced. − …”

“…Pellets have been generally prepared by 2 approaches: (i) manual compression of a dry BIAS (or SiO 2 support)/binder/additive mixture , and (ii) wet mold-casting or extrusion of a related solvent/BIAS paste then drying. − ,, The superior method (ii) can be subdivided into 2 categories: (a) prefunctionalizedpelletization of amine-impregnated BIAS particles and (b) postfunctionalizedamine impregnation of pellet supports prefabricated from SiO 2 particles. Ubiquitous, commercial mixer-extruders make method (ii) materials desirable for scale-up through semicontinuous or continuous operation of the equipment.…”

“…Our previous work showed that method (ii-a) BIAS/FA/polyvinyl chloride or PC pellets were adhered through a network of Si–/Al–OH···Cl– and Si–/Al–OH···Cl– 2 HN–/HN– hydrogen bonds, mechanically interlocked by FA particles. , Pellets with the PC/FA network were physically robust; demonstrated good CO 2 capture, 1.7–2.0 mmol CO 2 /g-pellet; and were resistant to thermal and steam degradation under practical conditions. However, 2 critical drawbacks that prevent scale-up production of these pellets are the toxic and costly 1,4-dioxane binder solvent and the necessary milling of raw PC chips into micron-sized particles to facilitate their solvation.…”