Comparative investigation on CO2 uptake performance of limestone-derived sorbents with different supports synthesized by impregnated layer solution combustion method

Abstract

Calcium looping is an effective post-combustion technology for CO2 separation from flue gas due to its low-cost and highly accessible sorbent raw material (i.e., limestone). However, limestone easily occurs serious sintering during multiple high-temperature carbonation/calcination cycles. Here, three types of modification mode, including acetic acid acidification, wet and dry solution-impregnated cigarette butts-assisted combustion methods, were adopted to enhance the cyclic stability of limestone. The impregnated layer solution combustion mode is superior to acid acidification, which is mainly ascribed to the heat released from the combustion of cigarette butt playing the role of thermal pretreatment, thereby stabilizing the pore structure of limestone-derived sorbents. Incorporating different inert supports can further enhance the cyclic stability of limestone-derived sorbents synthesized by wet solution-impregnated cigarette butts-assisted combustion. The effectiveness of several inert supports in improving the cyclic stability of limestone-derived adsorbents is listed as follows: CaZrO3 > MgO > Ca12Al14O33 > CaMn2O4. Moreover, the loading content of CaZrO3 within limestone-derived sorbents was further optimized, and it was found that 10 wt% of CaZrO3 sufficiently provides stable framework to inhibit high-temperature sintering (∼0.525 g-CO2/g-sorbent after 20 cycles). The uniformly dispersed CaZrO3 support at the nanocrystalline scale effectively inhibiting sintering is responsible for the excellent cyclic CO2 capture capability of CaZrO3-supported sorbents.