One-step synthesis of porous Li4SiO4 pellets by polyvinyl alcohol (PVA) method for CO2 capture

Li4SiO4 has shown great prospects for cyclic high-temperature CO2 capture due to its excellent stability, high capacity and low regeneration temperature. However, dense morphology and attrition problem are the main obstacles that lie in its way to the practical applications. This work, for the first time, proposed a simple polyvinyl alcohol (PVA) technique for the one-step preparation of porous spherical Li4SiO4 pellets. The produced pellets exhibited a uniform diameter distribution of 2.5-3.5 mm and high capacity of 0.320 g CO2/g sorbent. Besides, the PVA method-derived Li4SiO4 pellets also presented excellent cyclic stability in the extended sorption/ desorption operations of 30 cycles. It has been indicated that the enhancement of CO2 sorption capacity is ascribed to the formation of abundant pore channels and cavities resulted from the burning out of the well -dispersed polyvinyl alcohol. Moreover, the influence of CO2 presence at desorption stage on the sorbent per-formance was also investigated. It was indicated that the existence of CO2 at desorption stage caused sintering, which in turn resulted in the reduction of CO2 sorption capacity. In addition, the mechanical property of the pellets was tested. The weight loss was lower than 9 wt% over 2400 rotations in the anti-attrition ability test. In general, the high CO2 sorption capacity and satisfying mechanical property of the Li4SiO4 pellets via PVA route endows this method with promising prospects for the granulation of Li4SiO4 sorbents for realistic CO2 removal.