## 2 Experimental Section
### Data Process  
During the toluene conversion, toluene would be converted into H\({}_{2}\), coke, C\({}_{1}\) (CO, CO\({}_{2}\), and CH\({}_{4}\)), and high hydrocarbon. The content of non-condensable high hydrocarbon content was maintained at a low level, and it was neglected. Therefore, the outlet gas flow could be calculated using the N\({}_{2}\) balance method with known inlet N\({}_{2}\) flow. H\({}_{2}\) yield \(Y_{\rm H2}\) was defined as the amount of actual hydrogen production with the respect to the theoretical hydrogen from toluene. The C\({}_{1}\) yield \(Y_{\rm C1}\) was also similarly defined. The coke formation during the toluene step would be oxidized to form carbonaceous gas (CO and CO\({}_{2}\)) during  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Test** &
\begin{tabular}{c} **Oxygen** \\ **Carrier** \\ \end{tabular} & **Toluene** & **Steam** & **Temperature** & **Purpose** \\ \hline  & & **g/min** & **S/C** & \({}^{\circ}\)**C** & \\ \hline
1 & None & 0.286 & - & 750–1000 & Reference condition \\  & LaM (M = Fe, & & & \\
2 & Ni, Mn, Co and Cu) & 0.286 & - & 900 & Evaluate the effect of transition \\
3 & LaFe\({}_{1-x}\)Ni\({}_{x}\) (x = 0–1) & 0.286 & - & 900 & Optimize the ferrite with Ni substitution to enhance catalytic effect \\
4 & LaFe\({}_{1-x}\)Ni\({}_{x}\) (x = 0–1) & 0.286 & 0.8 & 900 & Promote yield of C\({}_{1}\) and H\({}_{2}\) by steam addition \\
5 & LaFe\({}_{0,6}\)Ni\({}_{0.4}\) & 0.286 & 0.8–2 & 800–950 & Optimize S/C and temperature, and evaluate oxygen carrier stability \\ \hline \hline \end{tabular}
\end{table}
Table 1: Main experiment parameters for toluene conversion.  
Figure 2: The diagram of the fixed bed for the chemical looping conversion of toluene.  
the following step. Therefore, the coke yield \(Y_{\text{C}}\) was defined as the amount of carbonaceous gas in the air step with respect to the amount of carbon in the toluene.  
\[F_{\text{out,fuel}}=\frac{1.2}{1-\sum W_{\text{i,fuel}}}\;(\text{i}=\text{CO}, \text{ CO}_{2},\text{ CH}_{4}\text{ and H}_{2}) \tag{1}\]  
\[Y_{\text{CI}}=\frac{92.14\times\int_{0}^{\text{t}}F_{\text{out,fuel}}\times(W_ {\text{CO,fuel}}+W_{\text{CO}_{2}\text{fuel}}+W_{\text{CH}_{4}\text{fuel}})}{22.4 \times 7\times 10\times F_{\text{toluene}}} \tag{2}\]  
\[Y_{\text{H2}}=\frac{92.14\times\int_{0}^{\text{t}}F_{\text{out,fuel}}\times W_ {\text{H}_{2}\text{fuel}}}{22.4\times 4\times 10\times F_{\text{toluene}}} \tag{3}\]  
\[F_{\text{out,air}}=\frac{1.2}{1-\sum W_{\text{i,air}}}\;(\text{i}=\text{CO}, \text{ CO}_{2},\text{ and O}_{2}) \tag{4}\]  
\[Y_{\text{C}}=\frac{92.14\times\int_{0}^{\text{t}}F_{\text{out,air}}\times(W_ {\text{CO,air}}+W_{\text{CO}_{2}\text{air}})}{22.4\times 7\times 10\times F_{ \text{toluene}}} \tag{5}\]  
where \(F_{\text{out,fuel}}\) and \(F_{\text{out,air}}\) represent the outlet gas flow during the toluene step and air step, respectively. The inlet N\({}_{2}\) flow is 1.2 L/min and \(W_{\text{i,fuel}}\) and \(W_{\text{i,air}}\) are the concentration of composition i (i = CO, CO\({}_{2}\), CH\({}_{4}\), and H\({}_{2}\)) in the toluene step and j (i = CO, CO\({}_{2}\), and O\({}_{2}\)) in the air step. The inlet toluene flow \(F_{\text{toluene}}\) is 0.286 g/min, and molar weigh of toluene is 92.14 g/mol. \(Y_{\text{CI,j}\text{ns}}\) and \(Y_{\text{H2,j}\text{ns}}\) were defined as the instantaneous yield of C\({}_{1}\) and H\({}_{2}\), respectively.  
\[Y_{\text{CI,ins}}=\frac{92.14\times F_{\text{out,fuel}}\times(W_{\text{CO,fuel }}+W_{\text{CO}_{2}\text{,fuel}}+W_{\text{CH}_{4}\text{fuel}})}{22.4\times 7 \times F_{\text{toluene}}} \tag{6}\]  
\[Y_{\text{H2,ins}}=\frac{92.14\times F_{\text{out}}\times W_{\text{H}_{2}\text {,fuel}}}{22.4\times 4\times F_{\text{toluene}}} \tag{7}\]