Waste oleaster seed-derived activated carbon mixed with coarse particles of fluid catalytic cracking as a highly-efficient CO2 adsorbent at low temperatures

Abstract

Activated Carbon (AC) derived from low-priced biomass materials has been identified as the efficient and cost-effective candidate for low-temperature CO2 adsorption technique performed, though suffering from limited CO2 capture capacity and heterogeneous fluidization in fluidized-bed systems have remained the main challenges for the industrialization of carbonaceous sorbents. Herein, for the first time, the novel, low-cost, and highly fluidizable carbonaceous sorbent derived from waste-based oleaster seed (OS) has been developed through mixing with cost-effective coarse fluid catalytic cracking (FCC) particles. Hydrophobic SiO2 nanoparticles (NPs) which are well-known as highly efficient assistant materials for enhanced fluidization of hard-to-fluidize particles was also tested for the comparison. To determine the best activator and activator/precursor weight ratio, AC sorbent obtained from the pyrolysis of OS was prepared with two disparate activators of KOH and ZnCl2, and the activator/precursor weight ratios of 2, 3, 4, and the outcomes reveal the highest average CO2 capture capacity of 2.78 mmol/g over three successive cycles for KOH-activated sorbent with activator/precursor weight ratio of 2. This great OS-derived sorbent was mixed with different wt% of coarse FCC and SiO2 NPs to boost its fluidity; for which, the bed expansion reached from 1.6 to 3.5, at the gas velocity of 5 cm/s by mixing with 2.5 wt% FCC, similar to 2.5 wt% SiO2 NPs-assisted sample. In addition to homogeneous fluidizability, a superior multicyclic stability of 95.5% during 25 multiple adsorption/desorption cycles was also assessed. The highly cost-effective FCC-mixed OS-derived activated carbon with both enhanced fluidity and multicyclic CO2 capture activity is introduced as the low-temperature CO2 capture candidate.