Fig. 3 illustrates the yields of liquefaction products (bio-oil and SR) at 573 K with different S/L ratios (5–15%). It is clearly shown in the figure that lower S/L ratio had positive impacts on the bio-oil yield. As the S/L ratio increased from 5% to 15%, the corresponding bio-oil yield decreased from 24.24% to 19.06%. Meanwhile, the SR yield increased with the increase of S/L ratio firstly, and then declined with the further elevation of S/L ratio.