Fe对Ni/SBA-16催化CO低温甲烷化促进作用的研究

Research on promotion of Fe in Ni/SBA-16 catalyzing CO methanation at low temperature

为了提高Ni/SBA-16催化剂在低温下CO甲烷化中的活性,通过引入Fe助剂制备了Ni-Fe/SBA-16双金属催化剂。对催化剂进行XPS、XRD、HRTEM及EDS-mapping表征的结果表明,Fe的加入与Ni形成了Ni_(3)Fe合金,减小了金属颗粒尺寸,使得还原后金属颗粒平均粒径从60 nm降低到30 nm左右。同时H_(2)-TPR的结果表明,Ni_(3)Fe合金的形成增强了金属Ni与载体之间的相互作用,从而能够减弱Ni颗粒在还原过程及反应过程中的团聚。最后,由CO-TPD和H_(2)-TPD的测试结果可知,Ni_(3)Fe合金的形成促进了催化剂对反应气体CO和H_(2)的解离,从而提高了催化剂在低温下的CO甲烷化活性。当空速为150000 h^(-1)、压力为0.1 MPa、V(H_(2))∶V(CO)∶V(N_(2))=3∶1∶1时,CO最低完全转化温度可以从300℃降低到250℃,同时CH_(4)的选择性保持在90%。

To improve the activity of Ni/SBA-16 catalyst in CO methanation at low temperature,Ni-Fe/SBA-16 bimetallic catalyst was prepared by introducing Fe promoter.The results of XPS,XRD,HRTEM and EDS mapping characterization of the catalyst show that the addition of Fe forms a Ni_(3)Fe alloy with Ni,which reduces the size of the metal particles and reduces the average particle size of the metal particles from 60 nm to about 30 nm after reduction.Meanwhile,the H_(2)-TPR results showed that the formation of Ni_(3)Fe alloy strengthened the metal-support interaction,which would weaken the agglomeration of metal particles during the process of reduction and reaction.Finally,the analysis of CO-TPD and H_(2)-TPD indicated that the formation of Ni_(3)Fe alloy promoted the dissociation of reactant gas(CO and H_(2)),thus enhancing the catalytic activity of CO methanation catalyst at low temperature.As a result,the CO minimum complete conversion temperature was lowered to 250℃ from 300℃ with a CH_(4) selectivity of 90%eventually at the condition of space velocity 150000 h^(-1),P=0.1 MPa,V(H_(2))∶V(CO)∶V(N_(2))=3∶1∶1.