Decomposition of Toluene in Coupled Plasma-Catalytic System

Abstract

The study of toluene conversion, in a gas such as the one obtained during the pyrolysis of biomass, was conducted at atmospheric pressure in homogeneous and in coupled plasma-catalytic systems. The effects of discharge power, initial concentration of toluene, and the presence of the bed of NiO/Al2O3 - G-0117 (industrial catalyst for methane water shift) on the conversion of C7H8, the composition of the outlet gas, and its calorific value have been investigated. The gas flow rate was 1000 Nl/h and the initial gas composition was CO (0.13), CO2 (0.12), H2 (0.25), and N2 (0.5). The initial toluene concentration was in the range of 2000–4000 ppm. The obtained results show that the conversion of toluene increases with discharge power and the highest one was obtained in the coupled plasma-catalytic system. It was higher than that in the homogeneous system of gliding discharge plasma. The composition of gas changed within the range of a few percent. In the outlet gas acetylene, ethylene and ethane were observed. Trace amounts of toluene were reduced to benzene and formed C3 and C4 hydrocarbons. In an extended process, the reduction of NiO to metallic nickel, methanation reaction of carbon oxides, and an increase of the conversion of toluene were observed. The conversion of toluene in the extended process was 92%. The catalytic activity of G-0117 in a coupled system increased during the study conducted for about 40 min. The use of G-0117 catalyst led to an increase in the calorific value of the outlet gas. In every examined system, it was above the minimal level demanded by engines and turbines. After the process, carbon deposits were present.

Plasma-Catalytic Process of Hydrogen Production from Mixture of Methanol and Water

“…Various plasma-catalytic systems are used. A catalyst may be located in a plasma zone [1][2][3][4][5][6][7], an electrode may be the catalyst [8,9], and often the catalyst is located outside the plasma zone [1,[10][11][12][13][14][15][16][17][18]. This way of placing the catalyst prevents the destruction of the catalyst by plasma and the disturbance of the discharge.…”

Decomposition of Tars on a Nickel Honeycomb Catalyst

“…The total gas flow rate was 1000 Nl/h. The reactor described in [4] was used for this study. The discharge power was in the range of 1500-2700 W. The gas upstream and downstream of the reactor was analyzed using gas chromatography.…”

“…Tar is a complex mixture containing carcinogenic, mono-and polycyclic aromatic hydrocarbons, which can condense in gas pipes and cause corrosion. The composition and concentration of tars in the gas depend on the type of biomass, its size, and the gasification conditions [2][3][4][5]. After processing, tars can be an additional source of gaseous fuels such as H 2 , CO, and CH 4 .…”

“…The use of pyrolysis gas as a fuel obtained from biomass requires its purification since gas engines require fuel of a specific purity. According to different sources, the concentration of tar substances cannot exceed the value of 50-100 mg/m 3 , and their content after gasification can reach up to 180 mg/m 3 [3][4][5].…”

Nickel catalyst in coupled plasma-catalytic system for tar removal

“…In previous studies, commercial catalysts were used in plasma-catalytic system. High toluene conversion was obtained (up to 99%) but large amount of soot was formed on catalysts surface 19, 20 . Amount of coke formed during tar cracking process increases with active phase concentration 21 .…”