Waste-to-energy: Kinetic and carbonation-decarbonation studies of solar calcined eggshells and their application as a catalyst in the pyrolysis of brewer’s spent grain
Year: 2025
Type: article
Abstract: Brewer’s spent grain (BSG) was subjected to pyrolysis using calcium oxide (CaO) derived from eggshells calcined via concentrated solar energy (Fresnel lens), offering an environmentally benign and low-carbon route for catalyst synthesis. A kinetic study using the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods determined the activation energy ranging from 284 kJ/mol for BSG to 176 kJ/mol for BSG/EG, indicating that CaO reduces the energy barrier for thermal decomposition. CO 2 capture performance of calcined eggshells was evaluated through multiple carbonation-regeneration cycles, showing reduced sorption capacity, mainly due to the sintering effect, yet maintaining acceptable cyclic stability for reuse. Despite having lower efficiency than commercial CaO, eggshell-derived material represents a sustainable and cost-effective strategy for CO 2 mitigation and catalytic applications. Central composite design (CCD) was used to evaluate the influence of pyrolysis temperature and catalyst loading on vapor composition. Highest hydrocarbon yields (∼50 %) were obtained at temperatures of 750 and 791 °C, using catalyst mass fractions of 74 % and 50 %, respectively. Lower relative yields occurred at 501 °C or the lowest catalyst loading amount (16 %). Catalytic tests at 550 °C produced similar hydrocarbon profiles to non-catalytic tests at 750 °C, indicating that the catalyst reduced the activation energy of the reaction. Increasing temperature and catalyst loading promoted deoxygenation, reducing multi-oxygenated compounds and enriching mono-oxygenated species, upgrading vapor quality. Overall, integrating solar-driven calcination with catalytic pyrolysis establishes a closed-loop waste-to-energy route that converts BSG into hydrocarbon-rich products while recycling eggshell waste into multifunctional CaO, advancing the circular economy and sustainable energy generation.
Source: Waste Management
Institution: Universidade Federal de Uberlândia
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,450
Funders: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Universidade Federal de Uberlândia, Ministério da Ciência, Tecnologia e Inovação, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Financiadora de Estudos e Projetos, Fundação de Amparo à Pesquisa do Estado de Minas Gerais
OpenAlex ID: W7116656883