The annual output of vanadium in China is 84,000 tonnes in 2017, accounting for 57% of the global output. It brought huge amount of vanadium slag, which caused serious pollution to soil and groundwater. Meanwhile, the emission of global CO2 has reached up to 37.15 billion tonnes by 2018, so the carbon emission reduction is still a big challenge. Cyclic CO2 capture with Ca-based sorbent has been considered to be an acceptable method, for its low cost and high efficiency. However, due to the sintering of traditional CaO sorbent under high temperature, the activity of sorbent would be rapidly reduced after several cycles. In this work, we proposed an easy and low-cost synthesis route to enhance both the cyclic stability and the sorption kinetics of Ca-based sorbent, through the dry-mixing of various calcium precursors and vanadium slag (containing 84.20% SiO2). Under the mild cyclic sorption conditions (calcination under pure N2), the as-synthesized sorbent (90%CaAc2+V-slag) reached a CO2 uptake of 0.46 g(CO2) g(sorbent)-1 in the first cycle after a short 5-min carbonation (at 700°C in pure CO2), and it showed a slight decline of 1.03% per cycle in the following 29 cycles. Even under severe conditions (calcination under pure CO2), “90%CaAc2+V-slag” still possessed a relatively high CO2 uptake of 0.28 g(CO2) g(sorbent)-1 after 30 cycles. Based on the characterization of XRD, SEM and TEM, it was concluded that the inert support in “90%CaCO3+V-slag” was larnite (Ca2SiO4). The stable larnite was formed by the reaction of CaO and vanadium slag, and thus could prevent the sintering of CaCO3 under high temperature. This new route to Ca-based sorbent could not only facilitate the recycling of vanadium slag, but also improve the cyclic stability and sorption kinetics for CO2 capture.

Novel synthesis of high-stable Ca-based sorbent for CO2 capture: Stabilizing effect of vanadium slag

2019 Fall National Meeting

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