Fig. 1. Concentration of acetic acid, eucalyptol, and the N-containing organics versus the residence time and reaction temperatures. ‘‘Original’’ in the x-axis means the
mixture of bio-oil with methanol at room temperature. ‘‘Mix’’ means the mixture of bio-oil, methanol, and Amberlyst 70 at room temperature. ‘‘0 min’’ means that the
temperature just reached the required reaction temperatures. Experimental conditions: catalyst loading: 5 wt.%; methanol/bio-oil mass ratio: 1.4.