110th Anniversary: Syngas Production Enhancement Using Calcium- and Potassium-Impregnated Chars

Syngas production enhancement via catalytic methane cracking onto metal-loaded chars, with a specific focus on the activity of two inherent alkali and alkaline earth metals (AAEMs), Ca and K, was investigated. Chars produced from the gasification of poplar wood pellets were heated to 700 °C in an inert atmosphere and then tested as catalysts for methane cracking at 700 °C. Methane is one of the most abundant biomass gasification byproducts. The cracking of this component is relevant in increasing the syngas production and yield. The syngas production was increased by a factor 1.9–2.7 using metal-loaded chars. Results were explained by the catalytic effect of AAEMs on both the desorption of oxygenated functional groups and on the catalytic methane cracking. AAEMs promoted methane molecule combination with the active sites such as oxygenated groups available at the surface of the chars enhancing both H2 and CO production. It was observed that potassium-loaded char (K-char) showed the best performance. The calcium-loaded char (Ca-char) was less efficient, due to a higher amount of silicon that interacted with calcium to form silicates. No synergetic effect was observed on the syngas production with the Ca+K-char.