Significantly Enhanced Methane/Nitrogen Selectivity in EMT Zeolite via Tetramethylammonium-Exchange Modification

Adsorptive CH 4 /N 2 separation holds great promise, yet remains a challenging effort owing to the limited availability of effective adsorbents. In this study, a series of tetramethylammonium (TMA)-modified EMT zeolites (EMT-TMA) were developed via ion exchange for CH 4 /N 2 adsorption separation. The suitable pore and incorporated functional groups of EMT-TMA contribute to a pronounced increase in CH 4 adsorption capacity, accompanied by a significant decrease in N 2 adsorption, resulting in a substantial enhancement of CH 4 /N 2 selectivity. In particular, EMT-TMA-34% exhibits a selectivity of CH 4 /N 2 up to 5.4 at 298 K and 100 kPa, far surpassing that of the pristine EMT (1.8). Grand canonical Monte Carlo (GCMC) calculations indicate that introducing TMA markedly increases the difference for CH 4 and N 2 affinity on the adsorbent. Breakthrough experiments and pressure swing adsorption (PSA) simulation further confirm its outstanding CH 4 /N 2 separation performances. This study converts previously ineffective materials in this area into highly efficient CH 4 adsorbents, with significant potential for industrial coalbed methane (CBM) upgrading. Download: Download high-res image (245KB) Download: Download full-size image