Effect of basicity of metal doped ZrO2 supports on hydrogen production reactions

Abstract

The basicity of ZrO2 support was successfully controlled by doping La and alkaline earth metals. La doping significantly increased weak basic sites, and medium and strong basic sites appeared by the further increase of La doping. Mg and Ca doping on La doped ZrO2 increased weak and medium basic sites, respectively. Significant increase of total number of basic sites including strong basic sites was observed by Sr doping. In ammonia decomposition, turn over frequency (TOF) of ammonia over Ru supported ZrO2 and metal doped ZrO2 exhibited a good relation to the number of medium and strong basic sites. From TOF with different reaction temperature, it was supposed that the higher basicity is effective to recombinative desorption of nitrogen at lower reaction temperatures, whereas the number of medium basic sites would be effective at a high reaction temperature. Catalytic activity in dry reforming of methane was evaluated over Ru supported ZrO2 and metal doped ZrO2 as well. The catalytic activity was improved by metal doping to the supports. Both TOF of CO2 and methane showed a good relation to the total number of basic sites as well as the number of medium and strong basic sites. It was interestingly found that H2/CO was increased with an increase in the total number of basic sites. This implies the weak basic sites would have a positive impact on H2/CO.