Ni/Al_(2)O_(3)催化剂输送床甲烷化反应特性

Methanation reaction characteristics of Ni/Al_(2)O_(3) catalysts in transport bed

采用浸渍法制备了三种NiO含量的催化剂,即αNi/Al_(2)O_(3),并对其在输送床反应器中的甲烷化特性进行了实验研究,考察了操作气速、松动风速、气体预热温度等操作条件对颗粒循环速率和催化性能的影响。结果表明,提高松动风速可以增加提升管内催化剂颗粒浓度,从而促进CO的转化;操作气速提高同样可以增加颗粒循环速率,但同时大大缩短气体在反应器内的停留时间,从而导致反应器出口CO转化率降低;催化剂的催化活性随着气体预热温度的升高显著提高,15Ni/Al_(2)O_(3)催化剂在气体预热温度为500℃,表观气速为2.1 m/s时,CO转化率仍高达83%;20Ni/Al_(2)O_(3)催化剂在气体预热温度为450℃,表观气速为2.1 m/s时,CO转化率高达98.7%;10Ni/Al_(2)O_(3)催化剂在气体预热温度为500℃,表观气速低于1.2 m/s时,CO转化率也可达95%,说明输送床甲烷化反应工艺适用较低活性组分含量的Ni基催化剂。

Three kinds of Ni/Al_(2)O_(3) catalysts with different Ni O contents(namelyαNi/Al_(2)O_(3))were prepared with impregnation,and the methanation characteristics in transport bed reactor were studied.The effects of operating conditions such as superficial gas velocity,aeration gas velocity and inlet gas temperature on particle cycle rate and catalytic performance were investigated.The results show that that increasing the aeration gas velocity can increase the concentration of the catalyst particles in the riser,so as to promote the conversion of CO.And the increase of aeration gas velocity can also increase the particle circulation rate,but at the same time,it can greatly shorten the residence time of gas in the reactor,resulting in the decrease of CO conversion at the outlet of the reactor.With the increase of the gas preheating temperature,the activity of the catalysts are obviously improved.The CO conversion of 15Ni/Al_(2)O_(3) is still as high as 83%when the gas preheating temperature is 500℃and the superficial gas velocity is 2.1 m/s.When the gas preheating temperature is 450℃and the superficial gas velocity is 2.1 m/s,the CO conversion of 20Ni/Al_(2)O_(3) is up to 98.7%.And the CO conversion of 10Ni/Al_(2)O_(3) is also up to 95%when the gas preheating temperature is 500℃and superficial gas velocity is less than 1.2 m/s.Therefore,the transport bed methanation reaction process is suitable for the Ni based catalyst with lower active component content.