###### Abstract  
In quest of a substantial reduction in potentially toxic gas emissions into the air from industrial plants, dry flue gas desulfurization (FGD) systems offer several advantages, such as reduced operational costs, adaptability, ease of use, and the elimination of liquid waste. This study describes the development of a laboratory-scale pilot system for conducting SO\({}_{2}\) abatement experiments using a fixed-bed reactor. To validate the experimental setup, the reactor was equipped with a control system for measuring and monitoring relative humidity, temperature, and total flux composition. The study utilized two standards, slaked lime and 13X zeolite, under identical experimental conditions to ensure comparability. This research will significantly advance the understanding of adsorbent materials for capturing low SO\({}_{2}\) concentrations by measuring adsorption kinetics and equilibrium data. The findings highlight the impact of distinct morphological, chemical, and crystallographic properties on the efficiency of dry FGD systems. desulfurization; zeolite; portlandite; sulfur dioxide; FGD +
Footnote †: journal: applied sciences  
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in the United States and China, where the limits for new plant installations are 350 and 90 ppm, respectively [5]. Flue gas desulfurization (FGD) technologies used to mitigate SO2 emissions in flue gases can be classified into three principal categories: wet, semi-dry, and dry systems. The classification is based on the physical condition of the adsorbent and of the waste product, which can be in the form of liquid, slurry, or ash. Wet FGD systems, which employ liquid-phase adsorbents such as limestone solutions, have historically dominated the market due to their high efficiency, achieving SO2 removal rates of 85-95%. However, SO2 residual concentrations of up to 150-450 ppm can still result in significant emissions from conventional FGD systems, contributing to dozens of megatons of global anthropogenic SO2 emissions annually from energy-related sources [6]. Furthermore, wet FGD technology sustainability is limited by high water consumption, low byproduct utilization rates, and the generation of secondary liquid waste [7]. Semi-dry FGD systems represent a cost-effective alternative, eliminating the need for reheating energy and wastewater treatment [8]. Since the 1980s, these systems have been commercially available, with the spray-drying process being the most suitable for the transformation of pre-existing power plants. Nevertheless, semi-dry systems are generally less efficient than wet systems [8]. For these reasons, it is expected that the global flue gas desulfurization market will experience the adoption of new strategies by leading players [9; 10]. Among these, dry FGD systems are emerging as the market's fastest-growing technology [6]. Indeed, they offer several advantages, including lower operational costs, adaptability, ease of use, and the absence of liquid waste (which can be disposed of alongside fly ash) [6]. In comparison to other dry FGD systems, the dry fixed-bed FGD process facilitates straightforward testing of novel adsorbents. This process has already found industrial applications in two steel companies with SO2 intake concentrations ranging from 250 to 800 ppm [11]. In one case, the temperature in the smelter off-gas was between 80 and 150 \({}^{\circ}\)C [11]. In addition to being proposed as an alternative treatment to wet FGD, the dry fixed-bed FGD can be suggested as a complement to the latter approach to entirely remove the exiting SO2.