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甲烷催化部分氧化制合成气固定床反应器的热波研究
THE THERMAL WAVE IN A FIXED-BED REACTOR FOR CATALYTIC PARTIAL OXIDATION OF METHANE TO SYNGAS
【摘要】 研究了 甲烷部 分氧化( P O M) 反 应 在 固定 床 反应 器 中 轴向 的 温度 场 分 布( 或 热波 分 布) .催化剂 床层的 热波呈不 对称分布 ,入口段 温度高 于出口温 度,热波 峰值位于 入口偏下 处. 考察了空速、n( C H4 )/ n( O2 ) 比值、高 径比 等对 热波 分 布的 影响 ,结 果表 明: 相 同外 温 下,增 加 空速 导 致 热波峰温升 高; 随 着 n( C H4)/ n( O2) 值 的降低,目 标产物 H2 和 C O 的深度 氧化( 强放 热) 加强, 故热 波峰温升高 ; 适当 降低催 化剂床层 的高径 比有利于 降低热波 峰温和 提高反应 性能. 催化 剂用 载体 稀释后,由于 H2 和 C O 深度氧 化反应 的加强,导 致热波 峰温 升 高. 不同 高 度催 化剂 床 层的 热波 特 征揭示, P O M 反应 主要在入 口段一 薄层区域 内进行 ,此区域近 似呈等 温分布,说 明 P O M 反应遵 循直接氧化机 理
【Abstract】 The thermal wave in a fixed bed reactor for catalytic partial oxidation of methane (POM) to syngas was investigated under various conditions, such as furnace temperature, space velocity, n (CH 4)/ n (O 2) and diluted/undiluted catalyst beds. The peak temperature of the thermal wave became higher as the space velocity was increased. The decrease of n (CH 4)/ n (O 2) led to a considerable rise in peak temperature, which was caused by the strong exothermic side reactions of deep oxidation of both H 2 and CO. A large rise in peak temperature was observed as the catalyst bed was diluted with α Al 2O 3 supports of the same particle size as the NiCe/ α Al 2O 3 catalyst (20~40 mesh). By comparing the catalytic performance as well as the thermal wave of the catalyst bed with a 3 mm height and that with a 15 mm height, it was clearly revealed that the POM reaction primarily took place in the upper zone (height 3~4 mm) of the catalyst bed, which was an almost isothermal region, and that the decrease of the lower part of the wave implied not the strong endothermic reforming reactions but the characteristics of the heat transportation for the product gases, because the lower thermal wave was not associated with the presence of the catalyst. These results supported a direct oxidation mechanism for POM.
【Key words】 nickel catalyst; methane; partial oxidation; syngas; fixed bed reactor; thermal wave;
- 【文献出处】 催化学报 ,CHINESE JOURNAL OF CATALYSIS , 编辑部邮箱 ,1999年03期
- 【被引频次】17
- 【下载频次】121