Investigation of modifying anti-sintering and oxygen uncoupling performance of CuO/TiO2 by MgO addition: Novel oxygen carrier

Abstract

Copper-based oxygen carrier is a strong candidate for commercial-scale chemical looping technology due to its high reactivity. In contrast, it has poor attrition and sintering resistance. Several supports have been used so far; however, they suffered from a high attrition rate under continuous operation. TiO2 has not been tested under continuous operation due to its poor sintering resistance, although it has the highest crushing strength. The novelty of this study is to use CuO/TiO2 and look to enhance its anti-sintering by MgO addition. Incipient wet impregnation method was used to synthesize 60 wt%CuO/40 wt%support (support:40 %TiO2, 30 %TiO2/10 %MgO, 20 %TiO2/20 %MgO, 10 %TiO2/30 %MgO, and 40 %MgO) calcinated at 890 °C for 7 h. XRD, XPS, SEM, and BET surface area have been used to characterize oxygen carriers. Oxygen uncoupling performance has been tested on a TGA at 920 °C through 10 cycles. The oxygen uncoupling capacity of all samples was around the theoretical value (6%); results also showed better uncoupling reactivity with a higher load of TiO2, while the sintering was also higher, as disclosed by SEM and BET. A fixed bed system was used for additional investigation; its results were almost identical to TGA. The results ascribed to high oxygen vacancies and copper concentration on the surface with a higher load of TiO2. So, all oxygen carriers have additionally calcinated for 48 h at 920 °C and tested again in a fixed bed, then the effect of sintering was dominant, and the reactivity was uniformly better with a higher load of MgO and sintering resistance.