Development of Adsorbents for Selective Carbon Capture: Role of Homo- and Cross-Coupling in Conjugated Microporous Polymers and Their Carbonized Derivatives

Abstract

Selective adsorption of CO2 from natural gas results in increased calorific value, decreased gas volume, and reduced corrosion. For this purpose, the development of high-performance adsorbents with regard to both adsorption capacity and CO2/CH4 selectivity receives great attention. Herein, two new conjugated microporous polymers (CMPs) were prepared by Yamamoto homocoupling and Sonogashira–Hagihara cross-coupling reaction. The significant role of homo- and cross-coupling in CMPs in selective CO2 separation was investigated. Notably, the cross-coupled CMP (NUT-15, NUT means Nanjing Tech University) shows CO2 uptake around twice that of homocoupled CMP (NUT-14) under the analogous conditions. Furthermore, the importance of KOH-activation and temperature-controlled carbonization in efficient CO2 capture was studied. For this, NUT-15 was further subjected to carbonization and highly active porous carbons (PCs) were obtained. It is noteworthy that PC-800 with high carbonization yield (78%) and suitable pore structure demonstrates excellent CO2 uptake (5.4 mmol·g–1) and selectivity (22.0) over CH4 at 273 K and 1 bar. Such CO2 uptake is higher than those of some benchmarks including activated carbon (2.8 mmol·g–1), PTz4 (3.6 mmol·g–1), and UTSA-50a (4.6 mmol·g–1) at 273 K and 1 bar. The high production yield, excellent CO2 uptake, and high selectivity make the present PCs promising candidates for selective CO2 separation from natural gas.