Warm Plasma Application in Tar Conversion and Syngas Valorization: The Fate of Hydrogen Sulfide

Abstract

Warm plasma techniques are considered a promising method of tar removal in biomass-derived syngas. The fate of another problematic syngas impurity—hydrogen sulfide—is studied in this work. It is revealed that processing simulated syngas with a microwave plasma results in hydrogen sulfide conversion. For different gas flow rates (20–40 NLPM) and hydrogen sulfide concentrations ranging from 250 ppm to 750 ppm, the conversion rate varies from ca. 26% to 45%. The main sulfur-containing products are carbon disulfide (ca. 30% of total sulfur) and carbonyl sulfide (ca. 8% of total sulfur). Besides them, significantly smaller quantities of sulfates and benzothiophene are also detected. The main components of syngas have a tremendous impact on the fate of hydrogen sulfide. While the presence of carbon monoxide, methane, carbon dioxide, and tar surrogate (toluene) leads to the formation of carbonyl sulfide, carbon disulfide, sulfur dioxide, and benzothiophene, respectively, the abundance of hydrogen results in the recreation of hydrogen sulfide. Consequently, the presence of hydrogen in the simulated syngas is the main factor that determines the low conversion rate of hydrogen sulfide. Conversion of hydrogen sulfide into various sulfur compounds might be problematic in the context of syngas purification and the application of the right technique for sulfur removal.

Role of Experimental, Modeling, and Simulation Studies of Plasma in Sustainable Green Energy

“…Toluene, being a model compound, decomposes in Ni/SiO 2 catalyst for syngas production. According to Wnukowski and Moro ń, the conversion of toluene in a microwave plasma generates heavy aromatic by-products, such as phenylethyne, indene, naphthalene, and acenaphthylene [26]. Moreover, tar removal from a real producer gas has also been attempted using microwave atmospheric plasma [77].…”

“…Furthermore, gasification using CO 2 is an interesting way of using captured CO 2 for energy purposes [23]. However, one of the most significant problems of gasification is related to byproducts of gasification-tars [24][25][26]. Tars are typically defined as a complex mixture of hydrocarbons with a molecular weight greater than the molecular weight of benzene [9].…”

Pioneering the Future: A Trailblazing Review of the Fusion of Computational Fluid Dynamics and Machine Learning Revolutionizing Plasma Catalysis and Non-Thermal Plasma Reactor Design

“…Byeon et al [39] investigated the removal of gaseous toluene and submicron aerosol particles using a dielectric barrier discharge reactor and reported toluene removal efficiencies ranging between 29% and 46%, depending on the applied voltage, frequency, upstream toluene concentration, and residence time. Nonetheless, caution is needed in such applications since the conversion of toluene in NTP could generate heavy aromatic byproducts, such as phenylethyne, indene, naphthalene, and acenaphthylene, as shown by Wnukowski and Moro ń for microwave plasma [40]. NTP plasma has been used for various applications related to gasification technologies, especially concerning gasification of waste [41] and removal of tars from producer gas [42], which is critical from the point of view of the maintenance and uninterrupted operation of gasifiers [43,44].…”

Advancing Sustainable Decomposition of Biomass Tar Model Compound: Machine Learning, Kinetic Modeling, and Experimental Investigation in a Non-Thermal Plasma Dielectric Barrier Discharge Reactor

“…Tar can be removed by primary and secondary methods [18][19][20][21]. In primary methods, tars are removed within the gasifier, while secondary methods involve post-gasifier treatment [22][23][24]. Thermal cracking, which is one of the methods of decomposition of tars, requires a relatively high reaction temperature of 800 • C [25], which leads to large energy consumption [24,26].…”