Negative CO2 emissions through iG-CLC of pinus residue in a continuous unit of 0.5 kWth using a natural Mn-based oxygen carrier

The use of renewable fuels, as biomass, in the chemical looping combustion process becomes an attractive solution to bioenergy technology with CO 2 capture (BECCS). In this work, a manganese ore from Brazil (MnT1000) was evaluated as an oxygen carrier to promote the conversion of a pine residue biomass by the in-situ Gasification-Chemical Looping Combustion ( i G-CLC) technology in a 0.5 kW th continuous experimental unit installed at ICB-CSIC. The main parameters studied were the influence of fuel reactor temperature, air excess, and oxygen-to-biomass ratio on the performance of the MnT1000 evaluating CO 2 capture efficiency and total oxygen demand. Under all experimental conditions, CO 2 composition was higher than 84% at the fuel reactor outlet gas on a dry N 2 -free basis. The unburned gases such as CH 4 , CO and H 2 were present in low concentration, attributed to the high reactivity that MnT1000 has with H 2 , CO and CH 4 . In general, higher temperatures, higher oxygen excess ratio and lower oxygen-to-biomass ratio reduced the total oxygen demand, with no great influence on CO 2 capture efficiency. Most of the experiments showed capture efficiency above 90%, and a total oxygen demand in between 5.9 and 13.7% for the experimental conditions studied with low specific solid inventories (760 – 833 kg MW −1 ). The amount of tar quantified in this study was low, corresponding to a total of 1.32 g Nm −3 , composed mainly of naphthalene and phenanthrene. In all experimental conditions, MnT1000 showed promising behavior, its reactivity remained high and constant throughout whole operation and no agglomeration problems were observed. • MnT1000 has high reactivity with H 2 , CO, and CH 4 . • MnT1000 kept its integrity and reactivity after 36 h of continuous operation. • i G-CLC process with MnT1000 showed CO 2 capture efficiency higher than 87%. • Experiments highlighted low tar formation at 900 °C. • With low specific solids inventory, low oxygen demand and low tars were achieved.