Experimental Investigation of the Hydrate-Based Gas Separation of Synthetic Flue Gas with 5A Zeolite

Xiaoya Zang,Xuebing Zhou,Deqing Liang,Na Zhang,Lihua Wan

doi:10.3390/en13174556

Abstract

Coal combustion flue gas contains CO2, a greenhouse gas and driver of climate change. Therefore, CO2 separation and removal is necessary. Fortunately, 5A zeolites are highly porous and can be used as a CO2 adsorbent. In addition, they act as nuclei for hydrate formation. In this work, a composite technology, based on the physical adsorption of CO2 by 5A zeolite and hydrate-based gas separation, was used to separate CO2/N2 gas mixtures. The influence of water content, temperature, pressure, and particle size on gas adsorption and CO2 separation was studied, revealing that the CO2 separation ability of zeolite particles sized 150–180 μm was better than that of those sized 380–830 μm at 271.2 K and 273.2 K. When the zeolite particles were 150–180 μm (type-B zeolite) with a water content of 35.3%, the gas consumption per mole of water (ngas/nH2O ) reached the maximum, 0.048, and the CO2 separation ratio reached 14.30%. The CO2 molar concentration in the remaining gas phase (xCO2gas) was lowest at 271.2 K in the type-B zeolite system with a water content of 47.62%. Raman analysis revealed that CO2 preferentially occupied the small hydrate cages and there was a competitive relationship between N2 and CO2.

Highlights

Various greenhouse gases, emitted by human activities, cause global warming, which continues to worsen
The CO2 emissions of coal-fired power plants account for 40% of total greenhouse gas emissions
Decreasing the CO2 emissions in the flue gas of power plants is critical to achieving CO2 emission reduction goals

Summary

Introduction

Various greenhouse gases, emitted by human activities, cause global warming, which continues to worsen. CO2 is the largest contributor to the greenhouse effect [1,2,3]. The CO2 emissions of coal-fired power plants account for 40% of total greenhouse gas emissions. Decreasing the CO2 emissions in the flue gas of power plants is critical to achieving CO2 emission reduction goals. Depending on the type of power plant, there are three main technologies for decreasing CO2 emissions: pre-combustion capture, oxy-fuel combustion, and post-combustion capture [4,5,6]. Based on the advantages and disadvantages of these three technologies, the most widely used, at present, is post-combustion capture. Post-combustion capture refers to the capture and separation of CO2 after coal has been burned. The main components of the flue gas are CO2 and N2.

Methods

Results

Conclusion