Syngas evolution and energy efficiency in CO2 assisted gasification of ion-exchanged pine wood

Abstract

In this study, the effect of ion-exchange sodium concentration on gasification process was first studied in a semi batch rector at 1073 K. In addition, four specific temperatures from 973 to 1223 K were further examined during gasification, with focus on the amounts of syngas components’ yield, energy yield, energy efficiency as well as the CO2 consumption for the raw and ion-exchange samples. Results showed that pine wood with higher ion-exchange sodium resulted in higher CO and syngas yield, while the acid washed sample provided the lowest syngas yield. Presence of ion-exchange sodium showed a strong catalytic effect on gasification, which enhanced the syngas yield and energy generation. Besides, the increase in gasification temperature led to enhanced syngas yield, cold gas efficiency and CO2 consumption, mainly due to its promotional effect on Boudouard reaction. Highest energy yield of 7.18 and 19.88 kJ/g, cold gas efficiency of 40.66% and 112.65%, and CO2 consumption of 0.74 and 1.75 g/g were found for the ion-exchange sample at 973 K and 1223 K, respectively. Overall energy efficiency showed a trend of first an increase followed by a decrease with time. The peak value of the ion-exchange sample was shifted to longer reaction time as compared to the raw sample. A maximum overall energy efficiency of 50.52% was obtained at 26.3 min for the ion-exchange sample at 1223 K. Therefore, temperature also offers a promotional effect on energy efficiency, which is of significant value in practical applications. This research provides a new insight to achieve maximum energy yield and efficiency with the help of ion-exchange species, in addition to the advantages of effective CO2 utilization.