Effects of alkali and alkaline earth metals (K, Na, Ca and Mg) of inherent minerals on Fe-catalyzed pyrolysis akuammiline alkaloids residue

In this study, the effects of inherent minerals K, Na, Ca, and Mg on the preparation of gas fuel and bio-oil by Fe-catalyzed pyrolysis were examined. Gas collection was conducted using a fixed-bed reactor, while bio-oil was detected using an online Py-GC/MS device. The results from the gas experiments demonstrated that the catalytic activity of the minerals adhered to the principle that alkali metals outperform alkaline earth metals (Na > K > Mg > Ca). Physicochemical characterization revealed that alkali and alkaline earth metals (AAEMs) facilitated the reduction and dispersion of the Fe catalyst, thereby reducing the average particle size. SEM analysis showed that Ca, which is resistant to removal by acid washing, encapsulated the Fe, whereas the addition of K, Na, Ca, and Mg diminished the interaction between Fe and Ca, thereby exposing more Fe active sites and enhancing the performance of the catalyst, it is only K and Na that have a stronger weakening effect than Ca and Mg. Furthermore, activity tests and kinetic analyses indicated that the incorporation of K, Na, Ca and Mg into the Fe-based catalyst promoted the max rate of biomass pyrolysis and reduced the apparent activation energy required for the reaction.