## 2 Materials and Methods
### Experiments  
Before the start of the experiment, two mixing methods were used to mix the catalyst with OS, including mechanical dry mixing and wet mixing. The dry-mixed sample was obtained by mixing 2 g of chloride with 20 g of OS powder and then shaking for 10 min in an oscillator, which was recorded as DMOS + C (DMOS + AlCl3\(\cdot\)6H2O, DMOS + MnCl2\(\cdot\)4H2O, DMOS + CrCl3\(\cdot\)6H2O, and DMOS + MoCl5). The wet-mixed sample was obtained by the following steps: First, 40 mL of deionized water was mixed with 2 g of catalyst powder to completely dissolve it. Then, 20 g of OS powder was added to the solution and heated and stirred for 30 min to fully mix. Finally, a wet-mixed sample, denoted as WMOS + C (WMOS + AlCl3\(\cdot\)6H2O, WMOS + MnCl2\(\cdot\)4H2O, WMOS + CrCl3\(\cdot\)6H2O, and WMOS + MoCl5), was obtained by drying the mixed solution at 80 \({}^{\circ}\)C for 10 h and then grinding it into powder below 80 mesh. The experimental apparatus used is shown in Figure 1, and the experimental steps are as follows. First, the raw OS (20 g), DMOS + C, or WMOS + C were placed inside a quartz retort (inner diameter of 50 mm and height of 140 mm), respectively. Next, the samples were heated from ambient temperature (30 \({}^{\circ}\)C) to the target temperature (400/520 \({}^{\circ}\)C) with a heating rate of 10 \({}^{\circ}\)C/min by an external heater in an N2 atmosphere and then held for 2 h. The nitrogen flow rate was maintained at 100 mL/min by a flow control device, which \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Proximate Analysis (wt.\%, ad)** & **Sd** & **Ultimate Analysis (wt.\%, d)** & **Sd** \\ \hline Moisture & 1.12 & 0.22 & C & 31.59 & 0.07 \\ Volatile matter & 43.24 & 0.26 & H & 3.99 & 0.03 \\ Ash & 54.26 & 0.14 & N & 0.30 & 0.02 \\ Fixed carbon & 1.38 & 0.21 & S & 0.79 & 0.01 \\ Calorific value (MJ/kg) & 12.02 & 0.08 & O & 9.06 & 0.02 \\ \hline \hline
**Fischer assay analysis (wt.\%, ad)** & & & & & \\ \hline Shale oil & 18.31 & 0.18 & & & \\ Water & 3.79 & 0.09 & & & \\ Residue & 67.39 & 0.18 & & & \\ Gases + loss & 10.51 & 0.15 & & & \\ \hline \hline \end{tabular} Note. ad: air dried; d: dried. Sd: Standard deviation.  
\end{table} 
Table 1: The proximate, ultimate, and Fischer assay analyses results of the raw Huadian OS. could effectively carry the oil and gas products out and avoid the temperature fluctuation caused by heat absorption. During the experiment, an ethylene glycol aqueous solution was used to condense the liquid products in a condensation tank at a temperature of \(-10\)\({}^{\circ}\)C. Additionally, the shale gas samples were taken at 0, 0.5, and 1 h after reaching the target temperature, respectively. After the experiment, the liquid products and OS residues were successively collected when the apparatus had naturally cooled down to ambient temperature. The obtained oil-water mixture was weighed and subsequently separated by a toluene-water azeotrope for assessment of their yields. For stability and repeatability, each experiment was repeated at least 3 times under the same conditions. Then, the results with a difference of less than 5% among the three groups were chosen, and the average value obtained was the final yield. The yield of shale oil is calculated as follows:  
\[\eta=\frac{m}{m_{0}} \tag{1}\]  
where \(\eta\) is the yield of shale oil; \(m\) is the final mass of shale oil, g; \(m_{0}\) is the initial mass of OS, \(m_{0}=20\) g.  
It should be noted that MnCl\({}_{2}\), CrCl\({}_{3}\), AlCl\({}_{3}\), and MoCl\({}_{5}\) have boiling points of about 1190 \({}^{\circ}\)C, 1300 \({}^{\circ}\)C, 180 \({}^{\circ}\)C, and 270 \({}^{\circ}\)C, respectively. So, the pyrolysis temperature will exceed the boiling point of some catalysts during the heating process. However, the solutions of the above catalyst are acidic when mixed by wet mixing. Carbonate minerals such as calcite in OS react in acidic solutions, and the reaction products are further transformed during the subsequent heating process, as experienced in the following Equations (2)-(9).