Recently there have been growing concerns that anthropogenic carbon dioxide ($CO_2$) emissions cause the global warming problem. Therefore, the cutting-edge technologies for the reduction, separation and collection of the $CO_2$ are very important to alleviate this problem. The best methods for reducing the $CO_2$ emission are to increase the energy efficiency and to remove it from the power plant. The $CO_2$ absorption from the syngas in the integrated gasification combined cycle (IGCC) might increase the energy efficiency of the power generation systems, which also contribute to mitigate the global warming. In this study, the suspensions of nanoparticles in methanol (called the nanofluid) are developed and estimated to apply it to absorb $CO_2$ gas in the IGCC systems. The nanofluids are prepared by the ultrasonic treatment and show the good stability. It is found that the $CO_2$ absorption rate by the nanofluid is enhanced up to ~8.3% compared to the pure methanol.