Catalytic Cracking of Endothermic Fuels over Meso-HZSM-5/MCM-41 Coatings

Abstract

Novel structured catalysts of meso-HZSM-5/MCM-41 composite coatings were synthesized via a two-step process: washcoating HZSM-5 powder on the internal surface of a stainless steel tube and subsequently converting SiO2 binder into MCM-41 by sequential desilication and recrystallization. Additional Fe and Al species were incorporated into the MCM-41 framework for increasing the active sites. It was found that the adherence strength of composite coating was remarkably improved, as a result of encapsulation of HZSM-5 crystals into the successive MCM-41 network. Catalytic cracking of supercritical n-dodecane (500 °C and 4 MPa) was employed to test the catalytic performance of the coatings. The ZC-Al/Fe coating with both Fe and Al species incorporated into the MCM-41 framework showed an excellent catalytic performance, with the initial conversion of n-dodecane enhancement by 50.6%, the deactivation rate reduction by 64.5%, and the heat sink improvement by 14.5%, compared to the parent HZSM-5 coating. The performance enhancement for ZC-Al/Fe coating may result from the sequential precracking–cracking–dehydrogenation reaction process catalyzed by acid sites in MCM-41, acid sites in meso-HZSM-5, and redox sites in MCM-41, respectively.

Liquid Ammonia as a Potential High Heat Sink Fuel via Catalytic Decomposition over Ru/CeO2–Al2O3 Coatings

“…Before the washcoating process, the stainless-steel tubes (1 m, Ø3 mm × 0.5 mm) were first washed by acetone. Then, the inner wall surface was etched by using 10 wt % HNO 3 solution and NaOH solution, respectively, to enhance the adherence of the coating. − After that, the tube was washed by deionized water and anhydrous ethanol sequentially. Finally, the tubes were dried at room temperature for 2 days, which were ready for the washcoating step.…”

Catalytic Decomposition of H2O2 for NO Oxidation‐Removal over Hierarchical Fe‐ZSM‐5: Effect of Ethanol on Zeolite Performance

“…The peak intensity for HT-1 was higher than that for HT-0, implying that ethanol in synthesis gel facilitated the formation of long-range ordered mesopores. [24,31] However, the peak intensity decreased with further increasing the ethanol dosage, suggesting that excessive ethanol in synthesis gel retarded both the MFI crystallization and the mesopore formation.…”

Synthesis of mesoporous Pt@KIT−6/SAPO−11 VIA in situ encapsulation to catalyze the decarboxylation of oleic acid to C8–C17 alkanes

“…[10][11][12] Although MCM − 41 has a good pore structure, it is only weakly acidic and it exhibits low catalytic activity during hydrocracking and isomerization reactions. 13 In contrast, HY and ZSM − 5 molecular sieves have abundant strong acid sites and the acidic site density of HY is higher than that of HZSM−5. Therefore, both molecular sieves show strong activity during the cracking of long-chain alkanes and tend not to generate alkane products with medium or long carbon chains.…”

“…Typical supports with acidic sites include MCM − 41, HY, ZSM − 5, SAPO−11, and other zeolite molecular sieves 10‐12 . Although MCM − 41 has a good pore structure, it is only weakly acidic and it exhibits low catalytic activity during hydrocracking and isomerization reactions 13 . In contrast, HY and ZSM − 5 molecular sieves have abundant strong acid sites and the acidic site density of HY is higher than that of HZSM−5.…”