Study On Reduction-Hydrogen Production Of CeO₂-modified Iron-based Oxygen Carrier Using Bio-oil Heavy Fraction

With the environmental pollution and the depletion of fossil fuels becoming more seriously, hydrogen is acknowledged as an ideal alternative energy source due to its non-polluting characteristic. Up to now, there are a variety of technologies proposed and applied to produce hydrogen, including traditional water electrolysis, steam-methane reforming and chemical looping hydrogen generation (CLHG) process. Among them, CLHG process could extract CO2 while making highly purified H2 in an efficient and environmental-friendly way and therefore has attracted great attention in past decades.Iron-based oxygen carrier with high oxygen transfer capacity has always been the key point in CLHG process. In this study, CeO2-modified iron-based oxygen carriers with the porous reticular structure were prepared by sol-gel method. XRD, SEM and BET were used to study the performance of the samples which was affected by different preparation parameters. Then, samples were tested in thermogravimetric analyzer (TGA) to study their reduction reaction performance and select the samples with excellent reducibility and strong resistance to carbon deposition or Fe3C formation. Finally, the candidates were tested in lab-scale fixed-bed reactor to evaluate their capacities of continuous hydrogen production under different gas concentration and different reaction temperature. The results confirmed that iron-based oxygen carriers modified by CeO2 could effectively inhibit carbon deposition or Fe3C formation. Samples prepared under the preparation conditions of Fe2O3/CeO2/Al2O3= 65/5/30 and C6H8O7·H2O/PEG00=3 stood out from all candidates by virtue of its highest hydrogen production efficiency and the excellent recycle ability in CLHG process. The sample at the optimal reducing atmosphere (CO/H2/N2=40/30/30 and the steam oxidation reaction at 900?) showed the best performance with the highest hydrogen yield (274.2mL/g and hydrogen concentration is almost 98%). The deactivation was not occurred during 20 redox cycles, indicating that the sample has high cycling stability.