CH4-CO2重整反应能实现CH4和CO2两种气体的利用，对控制温室效应、保护环境具有重要意义。开发低成本、高活性和高稳定性的重整催化剂是研究焦点。分别采用浸渍法和研磨-晶化法制备了负载型Ni/Q10(孔径10 nm的无定形SiO2)和嵌入型Ni@S1(Silicalite-1)催化剂，并用于CH4-CO2重整反应。采用XRD、BET、IR、H2-TPR、NH3-TPD、XRF、XPS、SEM、TEM和TG技术手段对催化剂结构进行了表征。研究发现，研磨-晶化法能有效调控Ni@S1催化剂中活性金属Ni的粒度和分散度，增强活性金属相与载体的相互作用。嵌入型结构能减少催化剂积碳，在700 ℃反应6 h后，5% Ni@S1催化剂的积碳量仅为5% Ni/Q10催化剂的46.83%。采用微型固定床连续反应对催化剂进行了活性评价（CH4/CO2/Ar=44.0/47.2/8.8、进料流速Fin=40 mL/min、反应温度T=700 ℃），发现反应6 h后，CH4在5% Ni@S1和5% Ni/Q10催化剂的瞬时转化率分别为72.82%和67.24%，与初始转化率相比分别降低了1.05%和7.99%；CO2瞬时转化率分别为79.06%和76.69%，与初始转化率相比分别降低了1.16%和4.54%。嵌入型Ni@S1催化剂在CH4-CO2重整反应中的活性和稳定性优于负载型Ni/Q10催化剂。

CH4-CO2 reforming reaction can realize the utilization of CH4 and CO2,which is of great significance to curb the greenhouse effect and environmental protection. Developing the reforming catalysts with low cost,high activity and high stability is of critical importance. Supported Ni/Q10(amorphous SiO2 with 10 nm pores) and embedded Ni@S1(Silicalite-1) catalysts were prepared by impregnation method and grinding-crystallization method,respectively,and they were used in CH4-CO2 reforming reaction. The structure of the catalyst was characterized by XRD,BET,IR,H2-TPR,NH3-TPD,XRF,XPS,SEM,TEM and TG. It is found that the grinding-crystallization method can effectively control the particle size and dispersion of active metal Ni in Ni@S1 catalyst,and enhance the interaction between active metal phase and carrier. The intercalation structure can reduce the carbon deposition of the catalyst,after reacting at 700 ℃ for 6 h,the carbon deposition of 5% Ni@S1 catalyst is only 46.83% of that of 5% Ni/Q10 catalyst. The activity of the catalyst was evaluated in a continuous fixed-bed reactor (CH4/CO2/Ar=44.0/47.2/8.8,Fin=40 mL/min,T=700 ℃). It is found that the instantaneous conversion of CH4 over 5% Ni@S1 and 5% Ni/Q10 catalysts are 72.82% and 67.24%,respectively,which decreases by 1.05% and 7.99% compared with the initial conversion rates.The instantaneous conversion rate of CO2 are 79.06% and 76.69% respectively,which are 1.16% and 4.54% lower than the initial conversion rates.The activity and stability of embedded Ni@S1 catalyst for CH4-CO2 reforming reaction are superier to those of supported Ni/Q10 catalyst.

0 引言

1 试验

   1.1 催化剂制备

   1.2 催化剂活性评价

   1.3 催化剂表征

2 结果与讨论

   2.1 催化剂的物相分析

   2.3 催化剂的红外分析

   2.4 催化剂的还原性分析

   2.5 催化剂的酸性分析

   2.6 催化剂的X射线荧光光谱分析和X射线能谱分析

   2.7 催化剂的形貌分析

   2.8 Ni含量对催化活性影响

   2.9 反应后催化剂积碳分析

3 结论