Acetaldehyde removal and increased H₂/CO gas yield from biomass gasification over metal-loaded Kraft lignin char catalyst

Acetaldehyde removal tests were performed to compare the catalytic activity of the Kraft lignin char (KC), KOH-treated Kraft lignin char (KKC), and activated carbon (AC) along with their impregnation with Mn in a plasma reactor. The gasification characteristics (syngas content, and H₂/CO ratio) of yellow poplar were investigated using nickel catalysts supported on KC, KKC, AC, and γ-Al₂O₃ in a U-type quartz reactor. KKC and Mn/KKC improved significantly the surface area and contents of O and N functional groups over the raw char. In particular, Mn/KKC showed the highest acetaldehyde-removal efficiency. The catalytic activity of Ni-impregnated KC, KKC, AC, and γ-Al₂O₃ decreased in the order of Ni/KKC > Ni/AC > Ni/KC > Ni/γ-Al₂O₃ for the gas yield and Ni/γ-Al₂O₃ >Ni/KC > Ni/AC >Ni/KKC for the oil yield, respectively. The Ni/KKC provides a more conducive environment for gasification, resulting in larger amounts of syngas (H₂ and CO) in the product gases. Moreover, Ni impregnated with char may be the most inexpensive and effective solution for achieving maximum tar reduction and syngas generation.