Pd/HZSM-5 coating catalyst for supercritical cracking of endothermic fuel

Pd/HZSM-5 coating was prepared on the inner wall of φ3 tubular reactor by gas-aided fluid displacement and electroless plating technologies. The coating was characterized by means of SEM, XRD, and XPS. The coating surface was flat without flaws, with thickness of 12–16 μm and catalyst particle of size 1–5 μm. Metallic Pd particles were uniformly dispersed on the coating surface. The coating was used as the catalyst for the supercritical cracking of n-dodecane, a typical model compound of endothermic fuel. With the temperature of 640°C, pressure of 4 MPa, and resident time of 10 s, Pd/HZSM-5 showed very high cracking ratio of 55.5%, hydrogen yield of 3.1%, and heat sink of 3470 kJ/kg, which were increased by 8.5%, 58.7%, and 10.5% compared with HZSM-5 coating, respectively. Furthermore, they were 17.3%, 78.1%, and 13.5% higher than the case of thermal cracking reaction, respectively.