Reforming of CO2-Containing Natural Gas Using an AC Gliding Arc System: Effect of Gas Components in Natural Gas

Abstract

The objective of the present work was to study the reforming of simulated natural gas via the nonthermal plasma process with the focus on the production of hydrogen and higher hydrocarbons. The reforming of simulated natural gas was conducted in an alternating current (AC) gliding arc reactor under ambient conditions. The feed composition of the simulated natural gas contained a CH 4 :C 2 H 6 :C 3 H 8 :CO 2 molar ratio of 70:5:5:20. To investigate the effects of all gaseous hydrocarbons and CO 2 present in the natural gas, the plasma reactor was operated with different feed compositions: pure CH 4 , CH 4 /He, CH 4 /C 2 H 6 /He, CH 4 /C 2 H 6 /C 3 H 8 /He and CH 4 /C 2 H 6 /C 3 H 8 /CO 2 . The results showed that the addition of gas components to the feed strongly influenced the reaction performance and the plasma stability. In comparisons among all the studied feed systems, both hydrogen and C 2 hydrocarbon yields were found to depend on the feed gas composition in the following order: CH 4 /C 2 H 6 /C 3 H 8 /CO 2 > CH 4 /C 2 H 6 /C 3 H 8 /He > CH 4 /C 2 H 6 /He > CH 4 /He > CH 4 . The maximum yields of hydrogen and C 2 products of approximately 35% and 42%, respectively, were achieved in the CH 4 /C 2 H 6 /C 3 H 8 /CO 2 feed system. In terms of energy consumption for producing hydrogen, the feed system of the CH 4 /C 2 H 6 / C 3 H 8 /CO 2 mixture required the lowest input energy, in the range of 3.58 · 10 À18 -4.14 · 10 À18 W s (22.35-25.82 eV) per molecule of produced hydrogen.

Reforming of CO2-Containing Natural Gas Using an AC Gliding Arc System: Effects of Operational Parameters and Oxygen Addition in Feed

“…Several reports have revealed that the addition of oxygen to a CH 4 -CO 2 feed gas mixture is one of the possible solutions for minimizing both the carbon formation and energy consumption for the CO 2 reforming reaction of methane [29][30][31][32][33]. Hence, in this present study, as the continuation of our previous work [28], the plasma reforming of CO 2 -containing natural gas coupled with partial oxidation was investigated using gliding arc discharge at different voltages, frequencies, and hydrocarbons (HCs)-tooxygen feed molar ratios. A comparative study between adding pure oxygen and adding air in the feed stream for the reforming of natural gas under gliding arc discharge was also conducted.…”

“…1. The details of the gliding arc reactor configuration and the discharge system were described in the previous paper [28]. The gliding arc reactor is made of a glass tube with a 9 cm OD and an 8.5 cm ID, and has two diverging knife-shaped electrodes that were fabricated from stainless steel sheets with a 1.2 cm width for each electrode.…”

“…The applied voltage and input frequency were adjusted by using a function generator. It should be noted that the voltage and current were measured at the low voltage side instead of at the high voltage side across the electrodes since the plasma generated is nonequilibrium in nature [28]. In addition, the optimum operational conditions obtained from the investigation of the effects of applied voltage and input frequency were used in the subsequent experiments of the combined plasma reforming and partial oxidation of the simulated CO 2 -containing natural gas.…”

“…In our previous work [28], the challenging concept of the direct utilization of raw natural gas with a high CO 2 content was investigated systematically. The study was carried out to observe the effect of feed gas components (CH 4 , C 2 H 6 , C 3 H 8 , CO 2 , and helium as the dilute gas) on natural gas reforming under non-thermal AC gliding arc discharge with the focus on the production of hydrogen and higher hydrocarbons at different feed flow rates.…”

Carbon dioxide reforming of methane in kilohertz spark‐discharge plasma at atmospheric pressure

“…15 Generally, gliding arc discharge showed lower energy cost (EC) than corona discharge, microwave discharge, or DBD. 16 However, the conversions of CO 2 and CH 4 in gliding arc discharges are relatively low.…”