Ca调变Ni基催化剂甲烷部分氧化制合成气

Partial oxidation of methane to syngas over Ca modified Ni based catalyst(Ⅱ)

在固定床流动反应装置上考察了不同反应条件对Ｃａ 调变Ｎｉ 基催化剂反应性能的影响。结果表明，当空速＜ ２－０ ×１０５ｈ － １ 时，随空速增加，反应性能也增加；当空速＞ ２－０ ×１０５ｈ － １ 时，空速对反应性能的影响较小；当 Ｖ（ＣＨ４）／ Ｖ（Ｏ２） ＝ １－８ ～２－１ 时，Ｖ（ＣＨ４）／ Ｖ（Ｏ２） 比减小，甲烷转化率增加、ＣＯ 及Ｈ２ 选择性变化不大；当 Ｖ（ＣＨ４）／ Ｖ（Ｏ２） ＞ ２－１ 时，增加 Ｖ（ＣＨ４）／ Ｖ（Ｏ２） 比，反应性能很快下降。在催化剂床层入口端加入少量贵金属Ｒｈ 催化剂可显著地降低反应的引发温度，反应性能不受影响。合适的高径比有利于提高反应性能，当高径比为０－３ ～０－６ 时有最佳的反应性能，在空速为２－０ ×１０５ｈ － １ ，Ｖ（ＣＨ４）／ Ｖ（Ｏ２） ＝ ２－０ ，Ｔｍ ＝ ９００ ℃时，Ｘ（ＣＨ４） ＞ ９６ ％ ，Ｓ（ＣＯ） ＞ ９５ ％ ，Ｓ（Ｈ２） ＞ ９９ ％ 。

The effects of different reaction conditions on the catalytic performance have been investigated in a fixed bed flow reactor.When the space velocity was lower than 2 0×10 5 h 1 ,the activity would rise with increasing space velocity.When higher than 2 0×10 5h -1 ,the space velocity had little effect on the reaction performance.When the molar ratio of CH 4/O 2 was between 1 8 and 2 1,the decrease of CH 4/O 2 ratio could raise CH 4 conversion,but showed less effect on the selectivity of both CO and H 2.When the ratio of CH 4/O 2 exceeded 2 1,the catalytic performance declined rapidly with the increase of CH 4/O 2 ratio. Adding a thin layer of Rh catalyst at the inlet of the nickle catalyst bed could decrease signigicantly the ignition temperature,and the catalytic performance kept almost unchanged.The desirable H/D ratio was much beneficial for the catalytic performance. As the H/D ratio was in a range of 0 3 and 0 6,an optimal catalytic performance could be obtained over the Ni based catalyst.With a space velocity of 2 0×10 5h -1 ,CH 4/O 2 ratio of 2 0 and at 900℃,the conversion of methane was higher than 96%,CO selectivity was higher than 95% and H 2 selectivity was higher than 99%.