DEVELOPMENT AND CHARACTERIZATION OF SOLID SORBENT FOR CO2 CAPTURE USING DATE SEEDS IN THE UAE

Abstract

Development of novel solid materials for post combustion carbon capture has been an essential research theme to solve existing challenges of the conventional amine absorption. Activated carbon (AC) as a solid adsorbent has inherent benefits of high specific surface area, good pore characteristics and adsorption capacity. Cost effective biomass wastes such as date seeds have been used to produce activated carbons for industrial use, but there have been no published studies on the potentials of the sorbent for carbon capture. In this study, activated carbons were synthesized from seeds of popular local date fruits in the United Arab Emirates (UAE) and investigated for carbon dioxide (CO2) adsorption. Synthesis of activated carbon was completed by both physical and chemical procedures in the temperature range 600- 900°C. Physical synthesis involved furnace pyrolysis with nitrogen and activation with CO2. For chemical activation, two agents (potassium hydroxide- KOH and sulfuric acid- H2SO4) were mixed in varying ratios with raw samples and directly heated to activation. The yield was found to be inversely proportional to the activating temperature and impregnating ratio. Characterization studies included surface area and porosity measurements, infrared spectra, and scanning electron microscopic images. The Brunauer–Emmett– Teller (BET) specific surface area and micropore volumes revealed the effect of varying activating temperature and impregnation ratio during synthesis. Presence of microstructures indicated that pore development influential to adsorption capacity had taken place during synthesis. Further structural changes were interpreted by the infrared spectra with observed decrease in oxygen or hydroxyl group with activation. CO2 adsorption tests were carried out using a micro reaction calorimeter. Heats of adsorption tests were also reported in the study. Physically activated samples with greater pore characteristics had higher loading capacity at room temperatures, with a record maximum loading of 141.14 mgCO2/gAC. Sulfuric acid activated carbons showed good capture capability in the range 40-80 mgCO2/gAC while KOH- samples had low adsorption capacities (< 20mg/g). Further testing involved samples impregnated with diethanolamine (DEA), and chemisorption performance varied depending on sample. The date seed sorbents can be suitable for pressure swing adsorption systems, and extensive testing on a pilot scale is recommended.

Date of Award	May 2017
Original language	American English
Supervisor	Mohammad Abu Zahra (Supervisor)