Metal–Organic Framework Adsorbent for Practical Capture of Trace Carbon Dioxide

Abstract

Control of indoor CO2 concentration to a safe level is important to human health. Metal–organic-framework-based adsorbents show superior adsorption performance at moderate CO2 concentration compared to other solid adsorbents but suffer from low capacities and high regeneration temperature at indoor CO2 concentrations and poor humidity stability. Herein, we report epn-grafted Mg2(dobpdc) (epn = 1-ethylpropane-1,3-diamine) showing a CO2 capacity of 12.2 wt % at an acceptable concentration of 1000 ppm and a practically low desorption temperature of 70 °C, which surpasses the performance of conventional solid adsorbents under the given conditions. After poly­(dimethylsiloxane) coating, this material reveals a significant adsorption amount (∼10 wt %) in humid conditions (up to 98% relative humidity) with structural durability.

Shaping of a Metal–Organic Framework–Polymer Composite and Its CO2 Adsorption Performances from Humid Indoor Air

“…36 This result implies that the epn-incorporating beads follow the CO 2 insertion mechanism, as found in diamine-functionalized Mg 2 (dobpdc) systems. 27 To examine the water stability, the working capacities of all of the samples were measured upon exposure to 60% RH at 25 °C (Figure 5b). The relative working capacity after water vapor exposure for 4 weeks decreased to 44% for epn-MOF and 70% for epn-MOF/PVDF30.…”

“…After the completion of the reaction, the light purple powder was separated via filtration, and DMF was poured into the powder to wash the solid several times. The powder and fresh DMF (300 mL) were placed in a 500 mL one-neck round-bottomed flask and heated for 12 27 For the amine functionalization process of the MOF powder, DMF-MOF was soaked in MeOH for 72 h upon daily exchange with fresh MeOH. The powder soaked in MeOH was vacuum-dried for 6 h at room temperature to obtain MeOHcoordinated Mg 2 (dobpdc) (MeOH-MOF).…”

“…A series of amines, including diamines, cyclic diamines, polyamines, alcoholamines, and alkoxyalkylamines, were utilized to graft the open metal sites of the Mg 2 (dobpdc) platform, only in the powdered form, for improved CO 2 removal capacity and selectivity. − Diamine-functionalized Mg 2 (dobpdc) systems are one of the desirable adsorbents that can adsorb CO 2 even at low pressures, but the humidity instability issues of bare MOF powders remain problematic. For practical applications, formulating amine-functionalized Mg 2 (dobpdc) materials into the shaped form is required to overcome processing limitations due to pressure drop, dust, clogging, loss of mass, and difficulties in handling and transportation. − Moreover, adsorbents for IAQ improvement should have moisture tolerance, as the relative humidity (RH) of closed spaces ranges from 25 to 60% at ambient temperature . Therefore, framework stability upon exposure to ambient indoor conditions is a prerequisite for practical applications, together with the shaping of MOF powders.…”

Synthesis, Characterization and Application of Amine-Functionalized Hierarchically Micro-Mesoporous Silicon Composites for CO2 Capture in Flue Gas

“…Adsorbents are the foundation for the adsorption process. In recent years, many porous solid adsorbents have been investigated in order to capture CO 2 from flue gas, including carbon materials [ 14 , 15 , 16 ], zeolites [ 17 ], mesoporous silicon [ 18 ], pillared lamellar clays [ 19 ], and the metal-organic frameworks (MOFs) [ 20 , 21 ].…”

Design of an Intelligent Nanofiber-Based Solid Amine Adsorbent with High CO2 Capture Capacity and an Ultralow Regeneration Temperature

“…This type of material is beneficial for the high-pressure storage of CO 2 but is not beneficial for the adsorption and enrichment of the low concentration of CO 2 at normal pressure owing to its poor adsorption capacity. To further increase the CO 2 capture capacity of porous materials, amines were loaded onto porous materials and fibers by physical impregnation or chemical grafting to prepare porous-based − and fiber-based solid amine adsorbents , with higher CO 2 adsorption capacities (2–6 mmol/g). Zhang et al prepared three-dimensional disordered porous silica as the CO 2 adsorbent support and tetraethylenepentamine (TEPA) as the CO 2 adsorbent, and its CO 2 adsorption capacity was 5.09 mmol/g.…”