Ni/Al_2O_3催化剂上CH_4/CO_2重整的脉冲反应研究

CH 4/CO 2 Reforming Reaction over a Ni/Al 2O 3 Catalyst Using a Pulsed Flow Microreactor

报道了用脉冲反应研究Ｎｉ／Ａｌ２Ｏ３催化剂上ＣＨ４／ＣＯ２重整反应的结果．脉冲反应显示，在还原的Ｎｉ／Ａｌ２Ｏ３催化剂上，ＣＨ４在６７３Ｋ就开始发生分解，并有Ｃ２Ｈ６、Ｃ２Ｈ４生成．１０２３Ｋ下，ＣＨ４几乎完全分解．单纯的ＣＯ２则很难在还原的催化剂上发生反应，在９７３Ｋ以上的高温下才会有少量ＣＯ２分解生成ＣＯ．ＣＨ４／ＣＯ２的脉冲反应表明，当ＣＨ４在较低温度（约６７３Ｋ）下开始分解时，ＣＯ２也会发生分解，并生成ＣＯ．脉冲反应结果提出的ＣＨ４／ＣＯ２重整反应机理可能是：高温下，ＣＨ４首先在催化剂表面分解形成ＣＨＸ（Ｘ＝１－３）和积炭，并释放出氢．吸附在催化剂表面的ＣＯ２直接与表面ＣＨＸ或积炭反应，生成ＣＯ和／或氢．

The dry reforming of methane over a Ni/Al 2O 3 catalyst was studied using pulsed flow microreactor. Temperature programmed desorption of CO 2 and n C 4H 9 NH 2 showed that the catalyst surface is strongly acidic. Temperature programmed pulse reaction (TPPR) over the reduced catalyst indicated that CH 4 started to decompose at a lower temperature of 673 K with the formation of ethane and ethylene, and completely decomposed at 1023 K. However, pure CO 2 is difficult to decompose on the reduced catalyst, only small amount of CO was detected when CO 2 pulse reactions was carried out at 973 K. CH 4/CO 2 TPPR revealed that CO 2 easily reacted with the fragments of CH X(x=0-3) decomposed from CH 4 at temperatures higher than 673 K, and gave out CO and hydrogen. The mechanism of CH 4/CO reforming reaction is suggested in which CH 4 decomposes at high temperatures to form surface CH X(X=0-3), then CO 2 reacts with the CH X species to synthsis gas.