Selective hydrogenation of eggshell/clamshell to methane with the assistance of the alkaline earth and transition metals at room temperature

Abstract

Producing clean fuel using shell wastes (eggshell and clamshell) can eliminate food waste and alleviate the energy shortage. Mechanochemical hydrogenation of eggshell/clamshell was investigated at room temperature. The results show that the alkaline earth metals can effectively assist the hydrogenation of shell wastes to CH4. The calcium metal has a better effect, and the methane yield for the calcium-assisted hydrogenation of clamshell and eggshell reaches 45.04% and 33.30% with 100% CH4 selectivity. At the same time, the calcium-assisted methanation of shell wastes in the presence of transition metals (Fe, Co, Ni, Ru) was investigated. By doping Ru, the methane yield of clamshell and eggshell was improved to 52.62% and 54.76%, respectively. The milling time, rotating speed, hydrogen pressure, and the species of the doped transition metals influence the calcium-assisted methanation of shell wastes. This study provides an alternative method to eliminate shell wastes and produce clean CH4 fuel at room temperature.