碳捕集转化一体化工艺能利用CO2转化过程同步实现CO2富液再生,有望降低碳捕集转化整体成本。为评价生物甲烷化与碳捕集耦合的可行性,首先,在填料塔中考察了以4.2g/LNaHCO3、6g/LNa2CO3、微生物营养液配制的弱碱性吸收剂(pH=10)对模拟烟气中CO2的吸收性能;其次,在厌氧瓶内利用生物甲烷化过程对CO2富液开展5个周期的循环再生试验。结果表明,填料塔气体流量≤1.0L/min时,随液体流量增加,所有试验组CO2去除率逐渐上升并能稳定在80%以上,该填料塔液体流量宜≤0.9L/min;不同气体流量(0.4~1.2L/min)下填料塔体积总传质系数基本稳定在17~19mol/(h·kPa·m3);CO2吸收导致吸收液中NaHCO3增加、Na2CO3减少,二者变量比值在1.2~1.9。气体流量为0.6L/min、液体流量为0.7L/min时,在维持80%以上CO2去除率的前提下,该弱碱性吸收剂可循环使用6次,此时活性组分CO2-3利用率达89.5%,形成的CO2富液中总无机碳量为0.127mol/L,pH为8.82,能为生物甲烷化微生物提供适宜的生长环境。CO2富液循环生物再生试验表明,每次再生后的吸收剂CO2吸收量基本稳定在69.6~78.6mmol/L,且再生期间CH4产生过程具有良好的重复性;再生试验后,Firmicutes、Actinobacteriota等耐碱性门水平细菌得到一定富集;氢营养型产甲烷菌在再生前后古菌属中占比均接近99%,但再生试验期间弱碱性环境导致Methanobrevibacter相对丰度降低了19.5%,unclassified_f_Methanobacteriaceae增加了18.7%。初步证实了碳捕集耦合生物甲烷化工艺的可行性。

It is expected that integrated carbon capture and conversion (iCCC) will reduce the overall cost of carbon capture & conversionby leveraging the CO2 conversion process to simultaneously regenerate CO2-rich solutions. To assess the feasibility of coupling biomethanation and carbon capture, the absorption performance of a slightly alkaline absorbent (pH = 10) prepared with 4.2 g/ L NaHCO3, 6 g/ LNa2CO3 and a microbial nutrient solution for CO2 in simulated flue gas in a packed column was investigated. Second, the CO2-rich solution was subjected to a five-cycle regeneration experiment using the biomethanation process in anaerobic bottles. The results show that inthe flow-through mode, when the gas flow rate of packed column is≤ 1.0 L/ min, with the increase of liquid flow rate, CO2 removal ratesof all experimental groups gradually increase and can be stabilized above 80%, and the liquid flow rate of this packed column is suitable tobe ≤ 0.9 L/ min. Overall volumetric mass transfer coefficients of the packed column at different gas flow rates (0.4-1.2 L/ min) are generally stable between 17- 19 mol/ ( h·kPa·m3 ). As a result of CO2 absorption, NaHCO3 in the absorption solution increases andNa2CO3 decreases, with a ratio between 1.2 and 1.9. Under the condition that the CO2 removal rate is greater than 80%, the slightly alkaline absorbent can be recycled 6 times at a gas flow rate of 0.6 L/ min and liquid flow rate of 0.7 L/ min. The utilization rate of the active component CO2-3 reaches 89.5%, and the total inorganic carbon(TIC) of the formed CO2 -rich solution is 0.127 mol/ L at a pH of8.82, creating an environment conducive to the growth of biomethanation microorganisms. The results of the cyclic experiments on the bioregeneration of the CO2-rich solution reveal that the absorbed CO2 of the absorbent is basically stable in the range of 69.6-78.6 mmol/ Lafter each regeneration and the CH4 production is reproducible during the regeneration process. As a result of the regeneration experiment,alkali-resistant bacteria at the phylum level, such as Firmicutes and Actinobacteriota, are somewhat enriched. Approximately 99% of archaeal genera are dominated by hydrogenotrophic methanogens before and after regeneration, but the slightly alkaline environment duringregeneration results in a 19.5% decrease in the relative abundance of Methanobrevibacter and a 18.7% increase in the relative abundanceof unclassified_f_Methanobacteriaceae, respectively. In conclusion, the above experimental results indicate the feasibility of biomethanation combined with carbon capture.

0 引言

1 试验

   1.1 试验材料

   1.2 试验过程

   1.3 分析与计算方法

2 结果与讨论

   2.1 流通吸收性能

   2.2 循环吸收性能

   2.3 CO2吸收富液生物再生性能

3 结论