A kinetic model for H2 production by plasmolysis of water vapours at atmospheric pressure in a dielectric barrier discharge microchannel reactor
A kinetic model for H2 production by plasmolysis of water vapours at atmospheric pressure in a dielectric barrier discharge microchannel reactor
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DOI：
10.1016/j.ijhydene.2012.08.113
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发表时间：
2012-12
影响因子：
7.2
通讯作者：
F. Rehman;J. Lozano-Parada;W. Zimmerman
中科院分区：
文献类型：
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作者：
F. Rehman;J. Lozano-Parada;W. Zimmerman
建立了常压下低温等离子体条件下水蒸气解离的动力学模型，并对水解离的不同途径、反应时间尺度和关键动力学步骤进行了分析。考虑了一股纯水蒸气流。包括不同的分解途径，如解离反应、电子解离附着、解离电离反应、电离反应和解离激发反应，沿着在等离子体中产生和消耗的不同物质的其他途径。解离反应被发现占主导地位的水蒸气的plasmicrowave其次是电子解离附着反应是另一个重要的动力学步骤。发现反应时间尺度和浓度与电子密度直接相关，并在最大电子密度（1021 m −3）时达到各自的最高值（H2浓度，[公式：见正文]和τ反应时间为10− 2 s）。发现达到99%的氢气产量（H2的稳态浓度）的时间尺度约为10− 2 s，这表明在微等离子体反应器中可以利用非常小的功率来生产H2，这与已发表的理论一致（Lozano-Parada JH，齐默尔曼WB.动力学在等离子体微反应器设计中的作用。Chemical Engineering Science 2010; 65（17）：4925-30）。当模型以解离吸附途径（反应（8））作为分解水蒸气的主要反应运行时，H2的浓度从16 mol/m3降低到4 mol/m3。然而，它额外地将H−自由基引入到系统中，随后通过电子分离控制H的产生。详细分析了影响水蒸气塑化反应动力学的主要步骤。发现H-H原子的氢化反应对H2的产生不显著。H2生成的关键步骤是H与HO 2的反应。最后，提出了一种与动力学重要步骤相一致的机制。
A kinetic model has been developed for water vapour dissociation flowing at atmospheric pressure under nonthermal plasma conditions and analysed for different pathways of water dissociation, reaction time scales and key kinetic steps for H2production. A stream of pure water vapour was considered. Different pathways of decomposition such as, dissociation reactions, electron dissociative attachment, dissociative ionisation reactions, ionisation reactions and dissociative excitation reactions were included along with other pathways for different species produced and consumed with in plasmolysis. Dissociation reaction was found to dominate the water vapour plasmolysis followed by electron dissociative attachment reaction being the other important kinetic step. Reaction time scales and concentration were found to be in direct relation with electron density and reached their respective highest values (concentration of H2, [Formula: see text] and τreaction≅10−2s) at maximum electron density (1021m−3). The time scale for reaching 99% of hydrogen produced (steady state concentration of H2) was found to be around 10−2s which showed H2could be produced utilising very little power in micro-plasma reactors, in agreement with published theory (Lozano-Parada JH, Zimmerman WB. The role of kinetics in the design of plasma microreactors. Chemical Engineering Science 2010; 65(17):4925–30). When the model was run as dissociative attachment pathway (Reaction (8)) being the primary reaction to break water vapour, concentration of H2was reduced from 16moles/m3to 4moles/m3. However, it additionally introduces the H−radicals into the system which subsequently control the production of H by electron detachment. A detailed analysis was done to find out the major steps influencing the overall kinetics of water vapour plasmolysis. Recombination reaction of H–H atoms was not found to be significant for the production of H2. The key step for the generation of H2was the reaction between H and HO2. Finally, a mechanism consistent with the kinetically important steps is proposed.