Synthetic natural gas by hydrothermal gasification of biomass Selection procedure towards a stable catalyst and its sodium sulfate tolerance

摘要

Catalyst stability and tolerance towards dissolved inorganics are the main challenges for successful hydrothermal gasification of wet biomass.A continuously operating catalyst test rig was built.Synthetic liquefied wood(phenol,anisole,ethanol,formic and acetic acid)was chosen to represent real biomass.After initial screening in a batch reactor,the most promising skeletal nickel catalysts and Ru/C_(granular)were tested in the new rig,under demanding conditions(high feed concentrations,10-20 wt%,and high space velocities,2-34g_(organics)(g_(catalyst)h)~(-1))at 30MPa and around 400 °C.Skeletal nickel catalysts sintered rapidly but Ru/C was stable during 220 h of testing.The inorganic salt tolerance was examined by co-feeding Na2SO4.Ru/C deactivated over time;a possible mechanism was identified as irreversible sulfate bonding to Ru~(III)being formed in the redox cycle of biomass gasification.