Co₃O₄ Nanosheet Wrapped Commercial HZSM-5 for Promoting Catalytic Cracking of n-Decane and Anticoking Activities

Abstract

Endothermic hydrocarbon fuel has many advantages as a cooling medium in hypersonic aircraft; however substantial application has been greatly hindered due to easy coking, uncontrollable gas products, and low heat sink issues. Catalytic cracking of hydrocarbon fuel has been regarded as one of the most effective ways to improve the heat sink via modulating the cracking pathway. The incipient-wetness impregnation method was selected to load Co salts in commercial ZSM-5 in a large-scale manner; subsequent calcination in Ar gas resulted in Co 3 O 4 nanosheet wrapped HZSM-5 composites. Salinization treatment was adopted to facilitate the dispersion of catalyst in a nonpolar solvent. The ratio of Bronsted/Lewis acidity decreased from 8.00 to 2.79 after modification by Co 3 O 4 nanosheets. The synergistically catalytic effect between Co 3 O 4 nanosheets and ZSM-5 was beneficial to the generation of a larger gas production rate with higher content of alkene, and thus resulting in a higher heat sink than benchmarked fuels. Catalytic cracking of n-decane (C10) in the presence of 0.1 wt % Co 3 O 4 nanosheets@ZSM-5 could yield a heat sink as high as 4.64 MJ/kg at 758 °C, much higher than those of bare ZSM-5 (2.99 MJ/kg at 687 °C) and thermal cracking of C10 (3.77 MJ/kg at 728 °C). Meanwhile, the smart combination of Co 3 O 4 nanosheets and commercial ZSM-5 could effectively suppress the coke deposition on the external surface of composites, thus resulting in efficient catalytic cracking at elevated temperatures for obtaining a higher heat sink.

Taming the Redox Property of A0.5Co2.5O4 (A = Mg, Ca, Sr, Ba) toward High Catalytic Activity for N2O Decomposition

“…Figure A shows the Co 2p spectra of A 0.5 Co 2.5 O 4 . Two characteristic diffraction peaks attributable to Co 2p 1/2 and Co 2p 3/2 are noted at around 793.5 and 778.5 eV. − The Co 2p 3/2 spectra were divided into Co 2+ and Co 3+ characteristic peaks of valence states, and the fitting results are listed in Table . Note that the binding energy of the Co 2p 3/2 peak of the Co 3 O 4 catalyst is at 779.1 eV.…”

New Strategy for High-Performance Integrated Catalysts for Cracking Hydrocarbon Fuels

“…Catalytic dehydrogenation/cracking of hydrocarbon fuels, which can significantly accelerate the cracking rate and change the reaction path, is an effective method to achieve a high heat absorption capacity. − In view of the particularities of the microchannels (1–2 mm) of the aircraft cooling structure, the widely used loading method of heterogeneous catalysts, such as fixed-bed, is impractical . Additionally, the limitations imposed by the wall-coating technology on fuel flow and heat transfer, as well as the rapid deactivation of the catalyst at high temperatures, cannot be neglected. − …”

Pyrolysis and Coke Deposition of JP-10 with Decalin in Regenerative Cooling Channels

“…Previous research studies proposed that the endothermic ability of hydrocarbon fuels was mainly caused by significant formation of unsaturated hydrocarbons in gaseous products, − such as alkenes. Meanwhile, the consistence between heat sink and the production of light alkenes was proposed in the research studies of Sun et al and Zhou et al to illustrate the heat absorption capacity of hydrocarbon fuels. Hence, the content of light alkenes (ethylene, propene, and butylene) in the gaseous pyrolysis products was investigated to demonstrate the connection between heat sink and light alkenes in the pyrolysis of JP-10 with decalin.…”