Influence of temperature on ICCU-DRM using K-Li4SiO4 -Ni/Al2O3

Dual functional materials, containing K-Li4SiO4 sorbent as the sorbent and 10 wt% Ni/Al2O3 as the catalyst, were investigated for ICCU-DRM, and the influence of temperature (600, 625 and 650 °C) was focused ( The following content was copied from the above reference.

“As CO2 desorption velocity is seriously affected by temperature, the duration of pre-breakthrough stage is different under various temperatures. At 650 °C as shown in Fig. 4(c), there is almost no pre-breakthrough stage in the in-situ conversion due to the rapid decrease of CO2 desorption velocity. At the beginning of the conversion, the amount of CO2 is much higher than CH4, causing the occurrence of a significant side reaction (CO2+H2→CO+H2O) and making the mount of produced H2 is less than that of CO. Gradually, the content of CO2 becomes lower due to the dramatic reduction of CO2 release velocity, resulting in methane decomposition (CH4→C+2H2) and a H2/CO ratio bigger than 1. When reaction temperature is set at 625 °C, as presented in Fig. 4(a), the release velocity of CO2 decreases gently, and the pre-breakthrough time is about 7 min in the in-situ conversion process. Within this stage, the ratio of H2/CO in product is stable in the range of 0.95–1.05 and the conversion of CH4 and CO2 is 95% and 81%, respectively. It should be noted that the continuous consumption of CO2 by in-situ DRM accelerates the desorption of CO2 from K-Li4SiO4 following Le Chatelier’s principle, and results in a much more release of CO2 in the pre-breakthrough stage during ICCU-DRM than that without the presence of catalyst. Therefore, the actual ratio of CO2/CH4 is higher than the pre-set value, which reduces the CO2 conversion rate significantly. Further decreased reaction temperature into 600 °C, the release of CO2 becomes more gradual, and the time of pre-breakthrough stage extends to 15 min. However, as the temperature is too low to efficient conversion of CH4, the conversion of CH4 and CO2 during the pre-breakthrough stage is only 75% and 85%, respectively. In conclusion, the optimal operating temperature of K-Li4SiO4 and Ni/Al2O3 is 625 °C in ICCU-DRM. When the temperature is at 650 °C, CO2 release velocity of K-Li4SiO4 drops too fast to be integrated with the reforming. On the other side, Ni/Al2O3 catalyst cannot efficiently convert CO2 and CH4 at 600 °C.”


“Fig. 4. ICCU-DRM at (a) 625 °C; (b) 600 °C; (c) 650 °C.”

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