Solar thermal production of zinc and syngas via combined ZnO-reduction and CH4-reforming processes
Solar thermal production of zinc and syngas via combined ZnO-reduction and CH4-reforming processes
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DOI：
10.1016/0360-3199(95)00016-7
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发表时间：
1995-10
影响因子：
7.2
通讯作者：
A. Steinfeld;A. Frei;P. Kuhn;D. Wuillemin
中科院分区：
文献类型：
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作者：
A. Steinfeld;A. Frei;P. Kuhn;D. Wuillemin
ZnO 的热还原和 CH4 的重整联合进行了热力学和动力学研究。 ZnO + CH4 系统在 1200 K 和 1 atm 下的化学平衡组成由含有 Zn（蒸气）的单一气相和 H2 与 CO 的 2:1 混合物组成。总反应可表示为： ZnO(s) + CH4= Zn(g) + 2H2+ CO。在不同温度和还原剂 CH4 浓度下对 ZnO 粉末进行热重测量。 气体。获得的表观活化能为 146 kJ mol−1。通过应用收缩粒子模型，发现反应机理是由斯托克斯状态下的气膜扩散控制的。该反应也在太阳能炉中进行了研究，使用集中辐射作为高温过程热的能源（ΔH∘1200K= 440 kJ mol−1）。论证了其技术可行性。太阳能接收器由与复合抛物面聚光器耦合的流化床管式石英反应器组成。直接辐照的 ZnO 颗粒在 CH4 中流化，充当吸热器和化学反应物，而产生的 Zn 蒸气则被捕获在冷指冷凝器中。所提出的太阳能联合热化学工艺提供了从氧化锌和天然气同时生产锌和合成气的可能性，而不向大气排放温室气体和其他污染物。此外，它还为回收锌空气电池或通过水分解方案生产氢气提供了一条环境清洁的途径。
The combined thermal reduction of ZnO and reforming of CH4has been thermodynamically and kinetically examined. The chemical equilibrium composition of the system ZnO + CH4at 1200 K and 1 atm consists of a single gas phase containing Zn (vapor) and a 2:1 mixture of H2and CO. The overall reaction can be represented as: ZnO(s) + CH4= Zn(g) + 2H2+ CO. Thermogravimetric measurements on ZnO powder were conducted at various temperatures and CH4concentrations of the reducing gas. The apparent activation energy obtained was 146 kJ mol−1. By aplying a shrinking-particle model, the reaction mechanism was found to be controlled by gas film diffusion in the Stokes regime. The reaction was also studied in a solar furnace using concentrated radiation as the energy source of high-temperature process heat (ΔH∘1200K= 440 kJ mol−1). Its technical feasibility was demonstrated. The solar receiver consisted of a fluidized-bed tubular quartz reactor coupled to a compound parabolic concentrator. Directly irradiated ZnO particles, fluidized in CH4, acted as heat absorbers and chemical reactants, while the Zn vapor produced was trapped in a cold-finger condenser. The proposed solar combined thermochemical process offers the possibility of simultaneous production of zinc and synthesis gas from zinc oxide and natural gas, without discharging greenhouse gases and other pollutants to the atmosphere. Furthermore, it provides an environmentally clean path for either recycling Zn-air batteries or producing H2in a water-splitting scheme.