Ni改性Mo_(2)C/γ-Al_(2)O_(3)催化剂在逆水气变换反应中的应用

Application of Ni modified Mo_(2)C/γ-Al_(2)O_(3) catalyst in reverse water-gas shift reaction

以掺杂Y型分子筛的γ-Al_(2)O_(3)为载体,七钼酸铵(AMT)、六次甲基四胺(HMT)为原料,Ni CO_(2)·2Ni(OH)_(2)·4H_(2)O为改性助剂,通过共浸渍和程序升温炭化法制备了Mo_(2)C/γ-Al_(2)O_(3)(MCAS)和Ni改性的Ni-Mo_(2)C/γ-Al_(2)O_(3)(MNCAS)催化剂。采用XRD、ICP、N;吸附-脱附、TEM和EDS对其进行了表征,考察了其在逆水气变换反应中的催化性能。结果表明,MNCAS催化剂出现了Ni_(3)Mo_(2)N的特征衍射峰,Ni的加入有效改善了Mo_(2)C的聚集现象,并且该催化剂具有良好的介孔结构。MCAS催化剂对逆水气反应有较高的催化活性,300℃时CO选择性为93.87%,MNCAS-8催化剂[n(AMT)∶n(HMT)=1∶8,Mo和Ni的理论负载量分别为30%和5%,实际负载量分别为28.52%和4.51%]倾向于将CO_(2)转化成CH_(4),在低温段CH_(4)选择性达到84.37%,生成的Ni_(3)Mo_(2)N有利于提高CH_(4)的选择性。

Mo_(2)C/γ-Al_(2)O_(3)(MCAS)and Ni modified Ni-Mo_(2)C/γ-Al_(2)O_(3)(MNCAS)catalysts were prepared via co-impregnation and temperature-programmed carbonization usingγ-Al_(2)O_(3)doped Y molecular sieve as carrier,ammonium heptadolybdate(AMT)and hexamethylenetetramine(HMT)as raw materials,and Ni CO_(2)·2Ni(OH)_(2)·4H_(2)O as modifying agent.The synthesized catalysts were characterized by XRD,ICP,N;adsorption-desorption,TEM and EDS,and their catalytic performances in reverse water-gas shift reaction were further investigated.The analyses revealed that MNCAS catalysts displayed the characteristic diffraction peaks of Ni_(3)Mo_(2)N with a good mesoporous structure,in which aggregation caused by Mo_(2)C was effectively improved by the addition of Ni.Moreover,MCAS catalyst exhibited high catalytic activity for the reverse water-gas shift reaction at 300℃with CO selectivity of 93.87%.Meanwhile,MNCAS-8 catalyst[n(AMT)∶n(HMT)=1∶8,the theoretical and actual loading amount of Mo were 30%and 28.52%respectively,and those of Ni were 5%,and 4.51%,respectively]showed a conversion tendency of CO_(2)into CH_(4),the CH_(4)selectivity reached up to 84.37%at low temperature range,which could be attributed to Ni_(3)Mo_(2)N generated after Ni addition.