Abstract:

Cotton stalk-based activated carbons were prepared by phosphoric acid activation of cotton stalks (CS) in a fluidized bed. The Co-B catalysts supported on cotton stalk-based activated carbon were generated by the impregnation-chemical reduction method. Meanwhile, the prepared activated carbons and catalysts were characterized by nitrogen physisorption, FTIR, XRD and SEM. The effects of activation reaction parameters, reaction temperature and recycle times on hydrogen generating performance of the activated carbons supported Co-B catalysts were investigated. The optimal activation temperature, activation time and amount of activator (m_H3PO4/m_CS) for activation of cotton stalk were 500℃, 1 h and 0.75, respectively. Under these conditions, the as-prepared Co-B/C catalyst with 14.5% (mass) Co exhibited the best hydrogen generating performance with an average rate of hydrogen generation up to 12.06 L·min^-1·(g Co)^-1 at 25℃. Activation energy of hydrogen generation reaction on such catalyst was estimated to be 44.61 kJ·mol^-1. After five cycles, the catalyst retained 54% initial activity, exhibiting high activity and stability.

Key words: activated carbon, catalyst support, activation condition, Co-B/C catalyst, sodium borohydride, hydrogen production

摘要：

采用棉杆生物质废弃物为原料、H₃PO₄为活化剂, 在流化床中化学活化制备棉杆活性炭, 并将其作为载体负载Co-B组分, 制备了棉杆活性炭基Co-B催化剂(Co-B/C)。以该催化剂应用于硼氢化钠水解制氢, 系统考察了活性炭活化条件(活化温度、活化时间、活化剂用量m_H3PO4/m_CS)、水解反应温度及催化剂循环使用次数对催化产氢性能的影响。同时, 使用N₂物理吸附、FTIR、XRD和SEM等技术对活性炭载体及催化剂进行了表征。结果表明:在活化温度500℃、活化时间1 h、m_H3PO4/m_CS为0.75条件下制得的活性炭载体, 负载14.5%Co的催化剂表现出最佳催化性能:反应温度为25℃时, 平均产氢速率可以达到12.06 L·min^-1·(g Co)^-1, 催化剂表现了较高活性。催化产氢反应的活化能为44.61 kJ·mol^-1。循环使用5次后, 催化剂仍保持初次活性的54%。

关键词: 活性炭, 催化剂载体, 活化条件, Co-B/C催化剂, 硼氢化钠, 制氢