Catalytic pyrolysis of brewer's spent grain in spouted bed reactor using calcium oxide for upgrading oil

This study investigates the potential of brewer's spent grain as a fuel source through fast pyrolysis in a spouted bed reactor, aiming to contribute to sustainable fuel alternatives and the mitigation of the environmental consequences of fossil fuel consumption. Both non-catalytic and catalytic tests evaluated the effects of temperature, biomass feed rate, and catalyst concentration on yields and hydrocarbon composition. The intermediate temperature (550 degrees C) and biomass feed rate (960 g/h) were optimal for non-catalytic tests, favoring oil production. Additionally, the oil yield was enhanced with the use of CaO as a catalyst during the pyrolysis process. An optimization study identified conditions maximizing both liquid yield and hydrocarbon content. While catalytic tests showed a modest increase in oil yield compared to non-catalytic tests, the addition of CaO significantly improved oil quality by increasing hydrocarbon concentration and facilitating deoxygenation. Under optimal conditions, non-catalytic pyrolysis achieved a 41% liquid yield with 15% hydrocarbon content. For catalytic pyrolysis, optimal conditions yielded 43% oil with a hydrocarbon content of 33% and low water content. Moreover, the resulting oil exhibited a higher heating value (HHV) of 25.7 MJ/kg compared to the spent grain's 19.8 MJ/kg. Utilizing the CaO catalyst further increased the HHV value to 28.2 MJ/kg, highlighting its efficiency in enhancing liquid product quality. The solid products resembled mineral coals with higher energy density compared to the feedstock. This study highlights the potential of brewer's spent grain for fuel production in a spouted bed reactor and the CaO catalyst's effectiveness in improving liquid product quality.