## 4 Modified Steel slag as Catalysts
### Transesterification
At the same time, although no research has been carried out on the preparation of biodiesel and glycerol for hydrogen production, the above analysis and summary show great potential, providing new guidance for solid waste utilization and synthesis of efficient heterogeneous catalysts. This will increase the additional utilization value of steel slag, reduce solid waste pollution, and further promote the development of renewable energy. In Table 2, we summarize the research of steel slag in the above catalytic fields in the current research stage. The results showed that the modified steel slag as catalyst has the advantages of low cost, environmental friendliness, high catalytic efficiency, and good reusability. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Catalysis Field** & **Raw Material** & **Modification Method** & **Reference** \\ \hline \multirow{4}{*}{Catalytic pyrolysis} & 1. Steel slag & 1. Physical modification & \\  & & 2. High-temperature activation modification & [39] \\ \cline{2-4}  & 1. Pine sawdust & Loaded with Ni by wet impregnation and high & [40] \\  & 2. Steel slag & temperature calcined & [40] \\ \cline{2-4}  & 1. Electric arc furnace slag & & \\  & 2. H\({}_{2}\)CO\({}_{4}\) and NaOH & Compound modification & [41] \\ \hline \multirow{4}{*}{Organic matter degradation} & 1. Steel converter slag (SCS) & 1. Physical modification & [44] \\  & 2. Methanol and salicylic acid (SAM) & 2. Acid modification & [44] \\ \cline{2-4}  & 1. Steel converter slag (SCS) & 1. Physical modification & \\  & 2. Methanol and salicylic acid (SAM) & 2. Acid modification & [26] \\ \cline{2-4}  & 3. Co(NO\({}_{3}\))\({}_{2}\) & & \\ \cline{2-4}  & 1. Steel slag & Compound modification & [46] \\ \cline{2-4}  & 2. Cu & & \\ \hline \multirow{4}{*}{Electrocatalysis} & 1. Steel slag & 1. Physical modification & \\  & 2. Clay & 2. High-temperature activation modification & [43; 51] \\ \cline{2-4}  & 3. Pore & & \\ \cline{2-4}  & 1. Steel slag & & \\ \cline{2-4}  & 2. Zeolite & Compound modification & [32] \\ \cline{2-4}  & 3. Pore-forming & & \\ \cline{2-4}  & 1. Kaolin & & \\ \cline{2-4}  & 2. Steel slag & Compound modification & [31] \\ \cline{2-4}  & 3. NaHCO\({}_{3}\) & & \\ \hline \multirow{4}{*}{light catalytic} & 1. LD slag & & \\  & 2. HCl & & \\ \cline{2-4}  & 3. Dimethylformamide & Acid modification & [24] \\ \cline{2-4}  & 4.erephthalatic acid & & \\ \cline{2-4}  & 1. Steel slag & & \\ \cline{2-4}  & 2. Industrial Titanium Liquid & Compound modification & [57] \\ \cline{2-4}  & 3. Ammonia and H\({}_{2}\)O\({}_{2}\) & & \\ \cline{2-4}  & 1. Steel slag & Alkali modification & [29] \\ \cline{2-4}  & 2. NaOH & & \\ \hline \multirow{4}{*}{Transesterification} & 1. Steel slag & 1. Acid modification & [62] \\ \cline{2-4}  & 2. HCl3 NaOH and Na\({}_{2}\)CO\({}_{3}\) & 3. High-temperature activation modification & [62] \\ \cline{2-4}  & 1. ladle furnace steel slag & 1. Alkali modification & [26] \\ \cline{2-4}  & 2. NaOH & 2. High-temperature activation modification & [26] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Application of modified steel slag as catalysts in five catalytic fields.