Influence of Degassing Temperature on the Performance of Carbon Molecular Sieves for Separations Involving O₂, N₂, CO₂, and CH₄

Abstract

The effect of thermal pretreatment on the diffusion of O 2 , N 2 , CO 2 , and CH 4 at 298 K in the commercial carbon molecular sieve Takeda 3A was studied. The results indicate that pore mouth barrier controls nitrogen transport. For oxygen and carbon dioxide, however, two mechanisms are present. Pore mouth barrier control determines the transport at lower temperature degassing, and micropore diffusion is present with a high temperature degassing. When the degassing temperature is increased, the adsorption as a function of contact time is almost constant for O 2 and CO 2 , is almost null for CH 4 , and increases significantly for N 2 between 373 and 653 K. The rates of diffusion also increase with increasing degassing temperature, but more appreciably for N 2 , which results in a significant decrease in selectivity for O 2 /N 2 and CO 2 /N 2 separations. These separations are therefore more efficient for Takeda 3A if it is only subjected to temperatures lower than 373 K. On the other hand, for CO 2 /CH 4 , the separation is more efficient if the Takeda 3A sample is first submitted to a degassing temperature around 673 K.

Probing the Mechanism of Water Adsorption in Carbon Micropores with Multitemperature Isotherms and Water Preadsorption Experiments

“…Yet the presence of these groups appears to have negligible effect upon carbon dioxide equilibrium in Takeda CMS, according to Cansado et al 51 Outgassing at 400 °C, which is believed to cause the removal of surface groups at the micropore entrance, causes a negligible change in total carbon dioxide uptake. 51 On the basis of these results, it is proposed that the presence of oxygenated functional groups…”

Porous Organic Polymers for Post‐Combustion Carbon Capture

“…It has been reported that the amount of excess CO 2 uptake is directly related to the total pore volume as well as the BET surface area. [51] PPN-4, with the highest surface area (6461 m 2 g -1 ), showed excellent CO 2 adsorption at high pressure (3.89 mmol g -1 at 295 K, 50 bar). [107] Thus, targeting high-surface-area polymers is an effective method to synthesize materials with high CO 2 capacity.…”

“…[29,30] Therefore, commercial amine systems have been developing other approaches to tackle the problems inherent involved with aqueous amine capture. [31][32][33][34][35][36] As an alternative, porous solid materials have been demonstrated as potential media for carbon capture, [37][38][39][40] including zeolites, [41][42][43][44][45][46][47][48] porous carbons, [49][50][51][52][53][54][55] and silica. [56][57][58][59][60] Carbon capture by traditional sorbents, such as zeolites and porous carbons, is much more energy efficient as compared to aqueous amine solutions.…”

Relationships between the Charge–Discharge Methods and the Performance of a Supercapacitive Swing Adsorption Module for CO2 Separation

“…An alternative carbon capture medium is porous sorbents, including porous carbons, − zeolites, and silica . Porous sorbents are nonvolatile and noncorrosive in nature.…”