煅烧还原一步制备 Ni 基催化剂及在CH4-CO2重整反应中的应用

摘要

The Ni/C‐SiO2 series catalysts were prepared by the method of soybean oil grinding ,and were applied in the CH4‐CO2 reforming reactions .These catalysts were characterized by the XRD , TG‐DTG ,BET ,H2‐TPR ,CO2‐TPD and chemical properties of the catalysts were measured by the fixed bed continuous reactions .The results showed that the nickel elements in the catalyst were fully transformed into Ni0 after calcining in inert atmosphere N2 for catalyst precursor prepared by grinding method ,thus realizing the preparation of the mesoporous Ni‐based catalysts by one‐step of the calcination and the reduction .There were two types of carbon on the catalyst after the CH4‐CO2 reforming reactions ,one was the residual carbon source in the prepared catalyst ,and another causing catalyst deactivation was the carbon deposition produced in the process of the reforming reaction .The influences of the promoters , such as CeO2 , ZrO2 and La2 O3 on the catalyst properties were investigated .T he results indicated that the particle diameter of the Ni 0 in the Ni‐CeO2/C‐SiO2 ,Ni‐ZrO2/C‐SiO2 and Ni‐La2 O3/C‐SiO2 catalysts was decreased ,the reaction activity of the Ni‐CeO2/C‐SiO2 and Ni‐La2 O3/C‐SiO2 catalysts was enhanced ,and the carbon deposition on the Ni‐ZrO2/C‐SiO2 and Ni‐La2 O3/C‐SiO2 was reduced after the reaction compared to these of the Ni/C‐SiO2 catalyst .The promoter La2 O3 not only improved the activity of the catalyst ,but also reduced the amount of the carbon deposition on the catalyst . The total carbon conversion reached 52% for the CH4‐CO2 reforming reaction using the Ni‐La2 O3/C‐SiO2 catalyst .%采用大豆油研磨法制备了 Ni／C‐SiO2系列催化剂，并用于CH4‐CO2重整反应。通过XRD、TG‐DTG、BET、H2‐TPR、CO2‐TPD等对催化剂进行了物理性能表征，利用固定床连续反应对催化剂进行了催化性能测试。结果表明，研磨法制得的催化剂前驱体在惰性气氛N2中煅烧后，催化剂上的镍元素全部转变成了Ni0，实现了煅烧还原一步制备中孔Ni基催化剂。CH4‐CO2重整反应后的催化剂上存在两种炭，一种是催化剂制备时残留的碳源炭，另一种是重整反应过程中产生的可致催化剂失活的积炭。考察了助剂CeO2、ZrO2、La2 O3对催化剂性能的影响，结果表明，与 Ni／C‐SiO2催化剂相比， Ni‐CeO2／C‐SiO2、Ni‐ZrO2／C‐SiO2、Ni‐La2 O3／C‐SiO2催化剂中 Ni0的粒径降低了，Ni‐CeO2／C‐SiO2、Ni‐La2 O3／C‐SiO2催化剂的反应活性提高了，反应后Ni‐ZrO2／C‐SiO2、Ni‐La2 O3／C‐SiO2催化剂上的积炭减少了。助剂La2 O3不仅提高了催化剂活性，而且降低了催化剂上的积炭量，使用Ni‐La2 O3／C‐SiO2催化剂进行CH4‐CO2重整反应，总碳转化率达到了52％。