Support-Dependent Activity and Thermal Stability of Ru-Based Catalysts for Catalytic Combustion of Light Hydrocarbons
Hangqi Xia, Yuting Bai, Qiang Niu, Biao Chen, Feng Wang, Biao Gao, Lilin Liu, Xingyi Wang, Wei Deng, Qiguang Dai
Abstract
Ru-based catalysts are the most promising and concerned candidates for catalytic combustion of propane as one of light hydrocarbons (LHs). In this work, different supports such as SiO 2, Al 2 O 3, CeO 2, and Co 3 O 4 were investigated to unravel the nature of high activity for catalytic combustion of LHs, and effects of Ru content, high-temperature aging, high weight hourly space velocity, and H 2 O were focused on. The pristine CeO 2 was lowly active for catalytic combustion of methane, ethane, and propane ( T 90C3 > 400 °C), while the pristine Co 3 O 4 and doped Co 3 O 4 presented high activity ( T 90C3 < 200 °C), the loading of Ru sharply improved the activity of CeO 2 especially for ethane and propane ( T 90C3 < 150 °C) and observably depended on the Ru content, and the promotion of RuO x to Co 3 O 4 -based supports was inconspicuous. However, Ru/CeO 2 catalysts were inferior to catalytic combustion of methane and lowly resistant to the high-temperature aging compared with Ru/Co 3 O 4 catalysts. Based on characterization results and comparison with SiO 2 supports with different surface areas, the Ru–O–M interface or highly dispersed RuO x species were determined as the main active sites for catalytic combustion of LHs and as follows: Ru–O–Ce interface > Ru–O–Co interface ≈ Co 3 O 4 > highly dispersed RuO x ≫ CeO 2 . Ru-supported Co 3 O 4 and doped Co 3 O 4 especially Ce-doped Co 3 O 4 demonstrated superior versatile activity, stability, and resistance to high temperature and H 2 O under harsh conditions close to the real full-scale applications, which showed the potential to eliminate the industrial VOC emissions. By contrast, Ru/CeO 2 was considered to be promisingly practiced in the portable NMHC detection/monitoring system due to the huge difference in catalytic combustion of ethane/propane and methane. This work was considered to be attributed to the further understanding of the activation of C–H bonds, the optimization of Ru-based catalysts for catalytic combustion of LHs, and the rational screening of potential catalysts for different practical application scenarios.