Synthesis gas obtained from biomass gasification (i.e. biosyngas, a mixture of CO, CO2, H2 and impurities) is pertaining to the wider societal agendas not only as a sustainable source of fuels and chemicals, but also as a mean for dealing with global warming challenge. A major barrier in the commercialization of biomass gasification is the presence of bio-impurities such as NH3, HCl, H2S and tars in the gas products that are detrimental to downstream processes. Two important downstream processes are the conversion of syngas through (i) methanation (MET) for synthetic natural gas production and (ii) Fischer-Tropsch synthesis (FTS) for higher hydrocarbons. The exact role and effects of biomass-derived impurities on the catalysts used for these reactions are poorly known. In this work, the effect of three N-containing compounds (i.e. acetonitrile, ammonia and nitric oxide, introduced at various concentrations 100-30000ppm) on FTS (using a cobalt-based catalyst) and MET (using a nickel-based catalyst) was investigated by operando diffuse reflectance FT-IR spectroscopy (DRIFTS) at atmospheric pressure.