Synergistic decarbonization and desulfurization of blast furnace gas via a novel magnesium-molybdenum looping process

Abstract

In this work, a novel system for synergistic decarbonization and desulfurization of blast furnace gas (BFG) was proposed via a magnesium-molybdenum looping process (MMLP): MgO ↔ MgCO3 and MoO3 ↔ MoS2. The system is comprised of a desulfurization/decarbonization reactor (DDR) and a carbon–sulfur carrier regeneration reactor (CRR). The simulation was conducted for feasibility verification and parameter optimization with applied ASPEN Plus software. Four carbon–sulfur carriers, MgO-MoO3, MgO-Fe2O3, MgO-MnO2, and MgO-SnO2, were preliminary investigated for screening. Results indicate that MgO-MoO3 performs superior capability of synergistic decarbonization and desulfurization. Both water–gas shift and COS/CS2 hydrolysis can be promoted in the presence of MgO via the CO2 absorption and the sorption-enhanced organic sulfur hydrolysis. The effects of MgO/C and 2MoO3/S mole ratios, temperature, pressure, O2 flow rate, and H2O flow rate were intensively discussed. Excessive temperature (>240 °C) in DDR leads to a decrease in carbon removal efficiency. A suitable amount of H2O is beneficial for CO2 capture, organic sulfur hydrolysis, and water gas shift reaction while excessive H2O decreases the organic sulfur hydrolysis efficiency and increases the system energy consumption. Carbon removal efficiency (CRE) of 99.70%, sulfur removal efficiency (SRE) of 100.00%, and H2 yield at 0.276 kmol/h (BFG flow rate = 1 kmol/h) can be obtained under the typical conditions of MgO/C = 2MoO3/S = 1.1, temperature = 240 °C, pressure = 1 atm and H2O/(CO + COS + CS2) = 1.2, providing theoretical guidance for the synergistic removal of sulfides and COx of BFG.