Han-Qing Chen,Zhan-Kuo Guo,Shu-Xiang Xiang,Hui-Lin Jiang,Yun-Lei Teng
Directly converting metal oxide-adsorbed CO2 to CH4 at low temperatures is a more energy-saving method for achieving carbon capture and utilization. In this study, an Al2O3-supported Ni/CaO composite was greenly prepared by a mechanochemical method. It is found that CO2 capture and selective methanation can be realized over the Ni/CaO/Al2O3 composite at as low as 200 °C under static pressure conditions. The methane yields over the 10Ni/10CaO/γ-Al2O3 composite reach 70.05 and 388.5 μmol CH4 per g at 200 and 350 °C with approximately 100% selectivity to CH4. The experimental results show that the reaction time and temperature obviously affect the methanation yield over the Ni/CaO/Al2O3 composite. This work provides a facile energy-saving strategy for converting CO2 to CH4 at low temperatures.
A strategy of in-stack dry reforming of methane (DRM) is proposed by using La 0.6 Sr 0.2 Cr 0.85 Ni 0.15 O 3-δ -loaded Ni foam (LSCrN@NF) as a CH 4 –CO 2 reformer, fuel gas distributor, and anode current collector in a SOFC stack. The prepared LSCrN exists as a single phase in a perovskite structure ; its reduced form contains exsolved Ni nanoparticles embedded on the surface of the LSCrN substrate. Introduced into an NF, the reduced LSCrN@NF demonstrates high DRM activity that increases with the increase of LSCrN amount to an optimum of about 42%. With the LSCrN@NF in-stack DRM, the conversions of CH 4 and CO 2 into CO and H 2 increase. Thus, the electrode polarization resistance, including the cathode and anode , decreases to 0.62, 1.07, and 3.93 Ω cm 2 at 800 °C, 750 °C, and 700 °C, respectively. Consequently, the peak power density (PPD) of the cell using 45% CH 4 -45% CO 2 –10% N 2 as fuel is 1.17, 0.94, and 0.47 W cm −2 , significantly higher than that of the cell without LSCrN@NF in-stack DRM. In addition, the voltage of the cell with LSCrN@NF in-stack DRM is stable on a level between 0.81 and 0.82 V at 400 mA cm −2 and 750 °C for 270 h without detected carbon deposition in the Ni–Y 2 O 3 stabilized ZrO 2 anode. This LSCrN@NF in-stack DRM strategy is also adopted with a large-scale (13 × 13 cm 2 ) single cell, which shows an extrapolated PPD of 428.3 mW cm −2 at 750 °C and is operated for 40 h at 400 mA cm −2 without noticeable performance degradation .
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