# Influence of CeO\({}_{2}\) Addition to Ni-Cu/HZSM-5 Catalysts on Hydrodeoxygenation of Bio-Oil
## 3 Results and Discussion
### Effect of CeO\({}_{2}\) on the Catalytic Yield
#### 3.1.2 Main property of bio-oil  
The property of bio-oil after HDO is an important index for evaluating catalytic activity. Table 1 lists the main properties of bio-oil and upgrading oil at 270 \({}^{\circ}\)C for 1 h with different catalysts. Compared with those of the bio-oil, the main properties of the upgrading oil with different catalysts improved in varying degrees. The water and oxygen contents decreased significantly with significantly increasing high heating value. When the CeO\({}_{2}\) content was 15%, the oxygen content reached the lowest (21.7%), indicating that the HDO effect was at the optimum at this time. At 15% CeO\({}_{2}\), the water content of the oil phase was slightly high and the high heating value was slightly low, but the difference was negligible. Considering the oil yield and the effect of HDO, the Ni-Cu/15% CeO\({}_{2}\)-HZSM-5 catalyst appears to be suitable for the HDO process.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Properties**} & \multirow{2}{*}{**Bio-Oil**} & \multicolumn{4}{c}{**Upgrading Oil**} \\ \cline{3-6}  & & **Ni-Cu/** & **5\% CeO\({}_{2}\)–Ni–Cu/** & **15\% CeO\({}_{2}\)–Ni–Cu/** & **20\% CeO\({}_{2}\)–Ni–Cu/** \\  & & **HZSM-5** & **HZSM-5** & **HZSM-5** & **HZSM-5** \\ \hline Moisture content (wt\%) & 31.3 & 2.4 & 2.4 & 2.5 & 2.4 \\ High heat value (MJ/kg) & 13.0 & 33.1 & 33.2 & 33.0 & 33.1 \\ Oxygen content (wt\%) & 56.8 & 23.0 & 22.5 & 21.7 & 22.5 \\ \hline \end{tabular}
\end{table}
Table 1: The properties of bio-oil and upgrading oil with different catalysts at 270 \({}^{\circ}\)C for 1 h.  
Figure 1: The yield (\(\gamma\)) with different catalysts at 270 \({}^{\circ}\)C for 1 h.  
Figure 2: The yield (\(\gamma\)) of 15% CeO\({}_{2}\)–Ni–Cu/HZSM-5 under different reaction temperatures.  
The effect of HDO increased with the rise of reaction temperature, and the water and oxygen contents decreased with the increase of temperature (Table 2), indicating that the HDO effect of bio-oil gradually increased with temperature. However, the amount of coke deposited on the catalyst after the reaction increased rapidly at the reaction temperature from 270 to 300 \({}^{\circ}\)C. The coke content on the surface of the catalyst in the bio-oil HDO process was measured by TG analysis. The weight losses of the 15% CeO\({}_{2}\)-Ni-Cu/HZSM-5 catalyst at 250, 270, 300, and 330 \({}^{\circ}\)C for 1 h were 7, 15, 48, and 54%, respectively (Figure 3). The carbon depositions on the 15% CeO\({}_{2}\)-Ni-Cu/HZSM-5 catalyst were 7%, 15%, 48%, and 54% (wt%) after reactions at 250 \({}^{\circ}\)C, 270 \({}^{\circ}\)C, 300 \({}^{\circ}\)C, and 330 \({}^{\circ}\)C for 1 h, respectively. Temperature is one of the main factors affecting coke deposition, and it causes the deactivation of the catalyst. Y decreased rapidly between 270 \({}^{\circ}\)C and 300 \({}^{\circ}\)C. From the energy utilization perspective, 270 \({}^{\circ}\)C is the suitable temperature for HDO when the CeO\({}_{2}\) content is 15% of the Ni-Cu/HZSM-5 catalyst.