The pyrolytic conversion of methane for the production of hydrogen and carbon was investigated over nonporous $\alpha$-Al₂O₃ surfaces in the range of 900 - 1300 °C. Two devices were used: i) a single particle reactor to determine the carbon deposition rate at various temperatures and ii) a fixed bed in which both methane conversion and carbon deposition were measured.

It was observed that at 1000 °C and below, the selectivity towards carbon (and hydrogen) was initially low over fresh $\alpha$-Al₂O₃ (e.g. 38% at 250 s reaction time), increasing to 100% over time. Methane conversion was constant at 20% during this period. These observations point towards the presence of an activation process for the formation of carbon and hydrogen from the intermediates products (e.g. benzene) of methane pyrolysis. A temperature dependent maximum in carbon loading was observed. When this maximum carbon loading was reached, methane conversion also stopped completely, indicating 100% selectivity towards carbon and hydrogen.

Two kinetic models for carbon deposition were derived and applied. After parameterization of these models using single particle data, they were able to predict carbon growth and CH₄ conversion as function of temperature, specific bed area, carbon loading and gas composition in the new data set from the fixed bed.

甲烷热解制氢和碳的研究 $\alpha$-Al ₂ O ₃表面在 900 - 1300 °C 范围内。使用了两种设备：i) 单粒子反应器，用于确定不同温度下的碳沉积速率，以及 ii) 固定床，其中测量甲烷转化率和碳沉积。

据观察，在 1000 °C 及以下，对碳（和氢）的选择性最初低于新鲜 $\alpha$-Al ₂ O ₃（例如，在 250 秒反应时间内为 38%），随时间增加至 100%。在此期间，甲烷转化率恒定为 20%。这些观察表明存在从甲烷热解的中间产物（例如苯）形成碳和氢的活化过程。观察到碳载量的温度依赖性最大值。当达到该最大碳载量时，甲烷转化也完全停止，表明对碳和氢的选择性为 100%。

推导出并应用了两种碳沉积动力学模型。在使用单粒子数据对这些模型进行参数化后，他们能够预测作为温度、比床面积、碳负载和来自固定床的新数据集中的气体成分的函数的碳生长和 CH ₄转化。