Kinetics of carbon dioxide reforming of methane via nonequilibrium plasma reactions

Summary form only given. CO₂ reforming of CH₄ not only eliminates two greenhouse gases but also yields syngas which is preferable feedback for synthetic fuel. The conversions of reactants realized via corona plasma reactions were obviously higher than the equilibrium conversions at atmospheric pressure, and the plasma reactions were always rapid. Experimental results reflect the unique kinetics of nonequilibrium plasma reactions. Within nonequilibrium plasma, the temperature of energetic electrons (T_e) is far higher than the temperature of other particles (T). The dissociation reactions of energetic electrons with molecules, e + A rarr products, play an important role, so the kinetics of nonequilibrium plasma reactions should be different with that of gas reactions usually explained by the classical collision theory. According to the collision theory, the rate for gas reaction, A + B rarr products, is given by (-d C_A/d t) = K₁middotC_AmiddotC_B, and the rate constant K_c is calculated by K₁ = (8RT_e/pim_e)^0.5middotsigma₀ middot(1+E₁/RT)middotexp(-E₁/RT) where T is the reaction temperature, sigma is the collision cross section, and E₁ is the threshold energy. m_AB = (m_A+m _B)/(m_Amiddotm_B), m_A and m _B are the molar masses of A and B. We deduced the rate constant K₂ of the dissociation reaction in non-equilibrium plasma which may be expressed as K₂ = (8RT_e/pim _e)^0.5middotsigma₀middot(1+E₀ /RT_e)middotexp(-E₀/RT_e). Due to T_e being far higher than T and the molar mass of electron m _e being far lower than m_AB, K₂ is far larger than K₁ even if sigma₀, the col- ision cross section for the dissociation reaction, is some less than sigma. So the dissociation reactions are very prompt, and the CO₂ reforming via nonequilibrium can be rapid and may realize higher conversions. Using our experimental data resulted from CO₂ reforming via AC corona plasma reactions, we drew a macroscopic kinetics model expressed as -d C_CH4/d t = 0.10 exp (-11.72/W)C_CH4 ^0.53C_CO2 ^1.1 where the W is the input power during the plasma reactions