In situ immobilization of CO₂ from coal-to-hydrogen off-gas to co-produce calcium carbonate nanoparticles using a modified membrane reactor

A continuous production multistage staggered-flow membrane reactor for the in situ fixation of CO₂ from coal hydrogen exhaust gas with the co-production of nano-sized calcium carbonate was designed. The optimal reaction parameters were determined using one-way experiments and response surface analysis, resulting in a CO₂ concentration of 90 %, CO₂ gas flow rate of 1.00 L/min, Ca(OH)₂ mass fraction of 1.55 %, Ca(OH)₂ flow rate of 0.60 L/min, CaSt₂ additive mass fraction of 5 %, maintaining the temperature at 25 °C, and using modified membrane tubes with two-stage staggered flow. The in situ CO₂ fixation rate was >99 % and the resulting calcium carbonate nanoparticles were formed with particle sizes in the range of 50–100 nm. After XRD, TGA and FTIR analysis, the generated calcium carbonate nanoparticles have good physicochemical properties. The in situ immobilization of CO₂ from coal hydrogen exhaust gas using a two-stage staggered-flow membrane reactor had a good effect and the resulting calcium carbonate nanoparticles met the requirements of rubber additives.