Plasma catalytic degradation of BTX over ternary perovskite type La1 x(Co, Zn, Mg, Ba)xMnO3 nanocatalysts
Abstract Volatile organic compounds, as an emerging group of organic pollutants, have significant harmful effects on both human health and the environment. BTX, which consists of benzene, toluene and xylene, is the most important kind of these compounds, which is extensively produced in the oil and gas industry. To date, various treatment methods have been used to remove volatile organic compounds. Among them, the non thermal plasma technology has attracted more attention as an efficient technology for the removal of VOC compounds due to its numerous advantages. perovskite type metal oxides have recently been found to be effective catalysts for the total oxidation of VOCs. This research has been conducted in two steps. In the first step, a series of La0.8A0.2MnO3 (A: Co, Zn, Mg, Ba) nano catalysts were synthesized by sol gel method and then their catalytic activity for removal of BTX compounds were investigated in a non thermal hybrid plasma system with the dielectric reactor, among which La0.8Zn0.2MnO3 was the most active catalyst. In the next step, further studies focused on zinc doped perovskite nanocatalysts. The catalytic activity of La1 xZnxMnO3 (x 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) nanocatalysts was investigated where La0.8Zn0.2MnO3 catalyst showed highest removal efficiency by degradation 89.73% of benzene, 88.98% of toluene and 88.66% of xylene. It should be noted that product analysis was performed using GC analyzer. The effect of operating parameters such as plasma voltage, activation time, the amount of catalyst loading on optimal sample catalyst and air flow rate were further evaluated. The results exhibited that increasing plasma voltage, activation time and the amount of catalyst loading and PDC use will develop degradation percentage, reduce air flow rate and increase the process time. The physical and chemical properties of perovskite nanocatalysts were evaluated using XRD, SEM, EDX, FTIR, DRS, BET, TEM and SAED analyses. The XRD results suggested that all the samples demonstrated a typical pure perovskite phase. SEM analysis results confirm the formation of nanostructured catalysts and EDX analysis exhibited a good dispersion of elements in optimal photocatalyst. The FTIR results showed that all the characteristic absorption peaks of perovskite were present in synthesized samples. The EDX analysis exhibited a good dispersion of elements in optimal photocatalyst and the BET analysis also revealed that the optimal catalyst had higher specific surface area. Topography and morphology was determined by TEM analysis and the SAED results showed the catalyst structure. The reaction rate equations were also calculated.