High-Temperature and Low-Concentration Deep Flue Gas Desulfurization with Low-Si/Al (∼5)-Ratio Zeolite Na-SSZ-13

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Deep flue gas desulfurization (FGD) and sulfur dioxide (SO2) recovery require highly stable porous materials due to SO2's corrosive nature.
• Existing porous materials often struggle with stability and efficiency in demanding FGD scenarios.

Purpose of the Study:

• To synthesize and evaluate the performance of a stable microporous zeolite, Na-SSZ-13, for SO2 adsorption and recovery.
• To investigate the SO2 adsorption mechanism and assess its suitability for deep FGD under challenging conditions.

Main Methods:

• Synthesis of low-Si/Al-ratio Na-SSZ-13 zeolite.
• Systematic evaluation of dynamic SO2 adsorption performance, including stability (water, thermal, chemical) and selectivity.
• Column breakthrough experiments, GCMC simulations, DFT calculations, and in situ DRIFT analyses.

Main Results:

• Na-SSZ-13 exhibits exceptional water, thermal, and chemical stability.
• High SO2 affinity, adsorption kinetics, and extraordinary SO2/CO2 selectivity (2673 at zero coverage).
• Exceptional low-concentration SO2 adsorption capacity (4.6/2.7 mmol g⁻¹ at 0.1/0.002 bar) and efficient capture from flue gas mixtures at high temperatures (323–423 K).
• Achieved 96.5% SO2 purity during regeneration with excellent cycling stability.

Conclusions:

• Na-SSZ-13 is a highly stable and effective material for deep flue gas desulfurization and SO2 recovery.
• The Na+ counter-cations play a crucial role in selective SO2 adsorption via cation···SO2 interactions.
• This zeolite-based material shows significant promise for high-temperature, low-concentration SO2 capture applications.