(521bm) Renewable Activated Carbon Sorbents from Food Waste for the Adsorptive Desulfurization of Liquid Hydrocarbon Fuels

Adsorptive desulfurization (ADS) has shown the ability to produce sulfur free fuels under ambient conditions, avoiding the high energy requirements of the traditional hydrodesulfurization process. Using food waste derived activated carbons (FWAC) gives the added benefits of low sorbent cost and repurposing waste material. Carbon materials from other sources have previously been effective ADS sorbents.¹ FWAC materials have high surface area and a pore structure than can be tuned via the activation process to achieve the desired morphology ideal for ADS. To synthesize these sorbents, processed food waste was first washed to remove impurities and then dried, ground, and sieved for uniform particle size. The prepared food waste was pyrolyzed to produce biochar, which was steam activated to FWAC. By controlling the steam pressure, reactor temperature, and activation time, FWAC samples with different physical properties can be produced. Additionally, acid treatment with HNO₃ can modify the surface properties to improve adsorption. FWAC samples were characterized and fixed bed adsorption experiments measured their capacity for 4,6-dimethyldibenzothiophene (DMDBT) in octane model fuel consisting of 100 ppm sulfur with 1 wt% naphthalene. Breakthrough curves show that the highly mesoporous FWAC sorbents have exceptional capacity for DMDBT, surpassing ADS performance previously demonstrated by other materials.² This can be attributed to the presence of surface oxygen groups as well as large surface area and mesopore volume allowing for diffusion and adsorption of DMDBT. This technology is a promising solution to reduce the sulfur content of hydrocarbon fuels to below required limits at significant energy and cost savings compared to hydrodesulfurization. The use of renewable materials as sorbents in this process will further minimize the overall environmental impact.

1. Zhou, A.; et al. Catal. B Environ. 2009, 87, 190–199.
2. Lee, K. X.; et al. Eng. Chem. Res. 2019, 58, 18301–18312.