A comparative study on three reactor types for methanol synthesis from syngas and CO2

In this study, a comparative study was conducted on the three reactor types (the adiabatic, water-cooled and gas-cooled reactor) employed for the traditional syngas to methanol (STM) process to investigate their potential applications to the STM process with the CO ₂-rich feed gas or the CO ₂ hydrogenation to methanol (CTM) process. The temperature profiles in the axial and radial directions particularly the hot-spot temperatures, operating conditions and methanol yields for the reactors have been investigated using the thermodynamic analysis, the CFD method and the pseudo-homogeneous model. The capital costs for CTM process with the three reactor types have also been evaluated. Compared with the traditional STM process, the STM process with the CO ₂-rich feed gas and CTM process exhibited reduced hot-spot temperatures. The simulation results showed that the single-bed adiabatic (without internal cooling) reactor and the gas-cooled reactor exhibited potentials for the CTM process, where the hot-spot temperatures the hot-spot temperatures in the reactors can be within the typical operating temperature range (e.g., 220–280 °C) for the catalyst. Regarding the comparison of the three reactor types for the CTM process, the water-cooled reactor showed advantages in terms of efficient heat removal, low hot-spot temperature and relatively wide range of inlet temperature for control. The adiabatic reactor and the gas-cooled reactor demonstrated a relatively low and medium performance, and also a relatively low and medium capital cost, respectively, which indicates the potentials of the two reactor types in a small-scale CTM process.