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

Abstract

The spark-discharge plasma, generated between tubular and rotary-disc electrodes using a sine-wave high voltage with 5 kHz frequency, was explored for CO 2 reforming of CH 4 . Based upon the investigation on the effects of specific energy input and CO 2 / CH 4 ratio, the energy costs (EC) and fuel-production efficiencies (g) at various CO 2 / CH 4 ratios (r) in the same conversion range were compared and accordingly their sequences were given: EC CH 4 (r ¼ 0.5) and EC CO 2 (r ¼ 3) are the lowest; g(r ¼ 0.5) is the highest. Compared with other nonthermal discharge techniques, the kilohertz spark discharge exhibits low EC and high fuel-production efficiency, especially at high total-carbon conversions. Preliminary investigation on partial oxidation and CO 2 mixed reforming at (O 2 þ CO 2 )/CH 4 ¼ 0.5 exhibited high H 2 /CO ratio (nearly 2) and low total-carbon EC (0.59-0.96 MJ/mol, 58-77% of total-carbon conversion, and O 2 /(CO 2 þ O 2 ) ¼ 0.8).

Optimized mixed reforming of biogas with O2 addition in spark-discharge plasma

“…Â 3 m length). As described in our previous papers [5,16], the conversions of CH 4 ðX CH4 Þ; CO 2 ðX CO2 Þ; O 2 ðX O2 Þ, total-carbon ðX TC Þ and the carbon-based (C-based) selectivities of COðS CO Þ, C 2 H 2 ðS C2H2 Þ and the carbon balance (B C ) can be briefly stated as follows.…”

“…1 shows a diagram of the experimental setup. The detailed plasma reactor configuration and experimental procedures were described in detail in our previous papers [5,16,23]. Briefly, a stainless steel tube (as the high-voltage electrode) and a rotary stainless steel disc (as the ground electrode) with a 9-mm gap were placed into a quartz cylinder to compose the plasma reactor.…”

“…Among the reforming methods, the conventional catalytic method has the disadvantages of the high temperature required and the rapid deactivation of catalysts. A promising alternative is the nonthermal plasma, which is characterized by very high electron temperature but relatively low gas temperature, offering high reactant conversions at low temperatures without catalyst [5,7,8,16]. However, strongly endothermic dry reforming reaction would inevitably result in the high-energy cost.…”

Post-plasma catalytic oxidative CO2 reforming of methane over Ni-based catalysts

“…The H 2 /CO ratio reduced gradually from 1.5 to 1.1 with increasing the temperature from 600 to 1000 • C. At CH 4 :O 2 :CO 2 = 1:0.3:0.4, the temperature increased from 600 to 800 • C, X CH 4 , X CO 2 , X TC and C H 2 +CO increased rapidly from 49%, 10%, 39% and 56% to 91%, 90%, 91% and 95%, respectively; as temperature further increased to 1000 • C, they all increased slightly to 99%. Obviously, X CO 2 , X TC and C H 2 +CO were improved significantly with the addition of more CH 4 . The H 2 /CO ratio was almost kept at 1.4-1.5 in the temperature range of 600-1000 • C.…”

“…Dry reforming of methane (DRM) via simultaneous conversion of CH 4 and CO 2 has been proposed to produce syngas (H 2 + CO) [1][2][3][4][5]. However, it is strongly endothermic and suffers from high energy cost.…”