Carbon Dioxide Reforming Of Methane To Produce Syngas By Thermal Plasma

With the petroleum resources becoming increasingly exhausted, more and more attention has been focused on the exploitation of natural gas that is highly effective, clean and abundant worldwide. CH4 is a principal component of natural gas. Since both CH4 and CO₂ are major greenhouse gases and the plentiful sources of carbon. Therefore, how to utilize them is concerned not only to resource disposition in the future, but also to protection of the environment.Plasmas are defined as highly excited gases composed of electrons, ions, atoms, and molecules with different energetic states, which is the fourth state of matter. Plasma process offers a unique way to induce gas phase reaction, which is utilized in many chemical reactions. Depending on their energy level, temperature and electronic density, plasma state is usually classi?ed as a high temperature (or thermal) plasma and a cold (or non-thermal or non-equilibrium) plasma. Thermal plasma has many advantages such as high temperature, adjusted atmosphere and controllable magnetism etc. Thermal plasma with features of higher temperature and higher density of active particles could be more effective to implement the simultaneously conversion of methane and carbon dioxide. Compared with non-thermal plasma, thermal plasma enhanced methane conversion process could achieve higher conversions of reactants, as well as higher selectivity to the syngas.The effects of the molar ratio of CH₄/CO₂, total flux of feed gases and the plasma power were investigated. The results indicated that the reforming of CH₄ and CO₂ were performed by thermal plasma with a larger processing capacity, higher conversion of CH₄ and CO₂, and higher chemical energy efficiency and fuel production efficiency. When the molar ratio of CH₄/CO₂, the total flux of feed gases and the input electric power were CH₄/CO₂=1, 9.6m3/h and 3.4KW, respectively, the conversions of CH₄ and CO₂ were up to 92.2% and 88.3%. Under these optimal conditions, the other parameters were determined: the selectivies of H₂,CO and C2H₂ were also high to 66.2%,65.1% and 13.7%, and the chemical energy efficiency were 59.8%.Experiments of carbon dioxide decomposition, methane decomposition and carbon dioxide reforming of methane were investigated. The results show that the mutual promotion between carbon dioxide and methane in reforming process should be considered in order to obtain high conversion of CH₄ and CO₂.Experiments on synthesis gas preparation from reforming of methane by carbon dioxide with thermal plasma only and cooperation of thermal plasma with Ni-Ce/Al2O3 catalyst, which were packed in the post plasma zone, have been performed. No extra energy was needed to maintain the temperature of catalyst bed, the elevated temperature was maintained by the hot gases from plasma region. We investigated the effects of total flux on the conversions of reactants ,the selectivity of products, chemical energy efficiency and the catalyst coking rate; Besides, we discussed the role of Ce in the reforming reaction, when the molar ratio of CH₄ to CO₂, the nitrogen flow and the plasma power were 1/1, 0.8m3/h and 3.5KW. The results show that with the increase of total flux, the conversions of methane and carbon dioxide decreased gradually, the selectivity of H₂ and CO hardly changed except C2H₂, and the catalyst coking rate Rapidly increased. Respectively, Higher conversion of reactants, higher selectivity of H₂ and CO, higher chemical energy, and lower selectivity of C2H₂ of the process were achieved by plasma coupled with catalyst.Finally, the thermodynamic analysis of process of CO₂ reforming CH₄ to syngas by a thermal plasma was undertaken using the Aspen Plus simulation tool. It was found that the simulation results accord with the experiment results well.The experiments use CH₄ and CO₂ as stuff, which are very abundant in the nature, utilize thermal plasma reforming at normal temperature and pressure conversion of methane and carbon dioxide to syngas. It is important for providing a new source of chemical engineering raw material, reducing greenhouse gases exhaust, realizing the strategy of sustainable development.