摘要
分别以碳纳米球、碳纳米纤维和纳米石墨烯片为碳源,以七钼酸铵、硝酸镍和硝酸铜为原料,通过饱和浸渍程序升温碳化法分别制备了30%负载量的Mo2C/碳纳米球(Mo2C/A)、Mo2C/碳纳米纤维(Mo2C/B)、Mo2C/石墨烯(Mo2C/C)催化剂和1%Ni-Mo2C/碳纳米球(Ni-Mo2C/A)、1%Cu-Mo2C/碳纳米球(Cu-Mo2C/A)催化剂.通过XRD、CO-TPD、SEM对新鲜催化剂进行了表征,并考察了催化剂对逆水煤气反应的催化性能.结果表明,Mo2C/A催化剂与Mo2C/B、Mo2C/C催化剂相比有较高的CO2 转化率,但CO选择性略低于其他 2 种催化剂.通过将Ni-Mo2C/A、Cu-Mo2C/A与Mo2C/A对比研究可以发现,少量Ni和Cu的加入可显著提高Mo2C催化剂的逆水煤气反应活性,Ni对CO2 转化率提升大于Cu,但Ni的加入明显降低CO选择性,这说明Ni的加入更有利于CH4 的生成,尤其在低温段,300℃时Ni-Mo2C/A催化剂CO选择性仅为 85%,相反Cu-Mo2C/A催化剂有较高的CO2 转化率和CO选择性,因此Cu-Mo2C/A为较理想的逆水煤气反应催化剂.
Abstract
Carbon nanoballs,carbon nanofibers and graphene nanosheets were used as carbon sources,and ammonium heptamolybdate,nickel nitrate,and copper nitrate were used as raw materials,the catalysts of 30%supported Mo2C/carbon nanoballs(Mo2C/A),Mo2C/carbon nanofibers(Mo2C/B),Mo2C/graphene(Mo2C/C),and 1%Ni-Mo2C/carbon nanoballs(Ni-Mo2C/A),1%Cu-Mo2C/carbon nanoballs(Cu-Mo2C/A)were prepared by a saturated impregnation process and temperature-controlled carbonization method.The fresh catalyst was characterized by XRD,CO-TPD and SEM,and the catalytic performance of the catalyst was investigated.The experimental results indicated that Mo2C/A exhibited a higher CO2 conversion rate compared to Mo2C/B and Mo2C/C,yet its CO selectivity was marginally lower than that of the other two catalysts.Upon comparative study of Ni-Mo2C/A,Cu-Mo2C/A,and Mo2C/A,it was evident that the incorporation of minor amounts of Ni and Cu could significantly enhance the reverse water-gas shift activity of the Mo2C catalyst.While the addition of Ni enhanced the CO2 conversion rate more than Cu,the presence of Ni notably reduced the CO selectivity.This suggested that the incorporation of Ni was more favorable for the formation of CH4,especially at low temperatures.At 300℃,the CO selectivity of the Ni-Mo2C/A catalyst was only 85%.In contrast,the Cu-Mo2C/A catalyst exhibited both a higher CO2 conversion rate and CO selectivity.Therefore,Cu-Mo2C/A was considered the most desirable catalyst for reverse water-gas shift reactions.
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