Catalytic Cracking of n-Decane over Monometallic and Bimetallic Pt–Ni/MoO₃/La–Al₂O₃ Catalysts: Correlations of Surface Properties and Catalytic Behaviors

Abstract

Catalytic cracking of n-decane was performed over monometallic and bimetallic Pt–Ni catalyst supported La–Al2O3 modified by MoO3 (MLA), aiming to investigate the effects of acidity, active phase dispersion, and synergistic effect between Pt and Ni on catalytic performance of the catalysts. The catalysts were characterized by the techniques of Brunauer–Emmett–Teller (BET), hydrogen temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD), X-ray photoelectron spectroscopy (XPS), CO chemisorption, and transmission electron microscopy/energy-dispersive spectroscopy (TEM/EDS) mapping. The results showed that catalytic cracking activities over catalysts were heightened compared with MLA, especially bimetallic catalyst. Meanwhile, bimetallic catalyst exhibited the best high-temperature stability. Otherwise, cracking activity over regenerative bimetallic catalyst nearly approached that of the fresh one. The most effective findings of properties of bimetallic catalyst presented as follows: the unique acidity, higher resistance against sintering of active phases, and finely dispersed actives due to enhanced metal–support interaction and synergistic effect between Pt and Ni can be responsible for its stable catalytic activity and thermal stability, and capable regeneration.

Synthesis of a High-Stability Nanosized Pt-Loaded MgAl2O4 Catalyst for n-Decane Cracking with Enhanced Activity and Durability

“…The catalysts were characterized by some analytical techniques, including N 2 adsorption–desorption, XRD, NH 3 -TPD, and CO chemisorption according to the procedures described in our previous works. − The micro-morphological characteristics of fresh PMA and PMA-V catalysts were observed using a Talos F200x (FEI, USA) transmission electron microscope (TEM). In this work, the Pt particle size was obtained by counting 100 Pt particles in 5–10 TEM images.…”

“…Appropriate catalysts can increase the heat-absorption capacity by improving the selectivity of preferred products (like low-carbon alkenes) and conversion. Based on related literatures, − two kinds of catalysts, including pseudo-homogeneous catalysts − and wall-coated catalysts, − are broadly studied for the EHF cracking reaction.…”

“…Wall-coated catalysts are another kind of commonly used catalysts in EHF cracking at present, and the coatings are mainly concentrated in zeolites and composite oxides. − On the one hand, Liu et al, Ji et al., Sang and Li, Konno et al, and Diao et al . all found that ZSM-5 and modified ZSM-5 zeolites had a good catalytic effect on EHF cracking.…”

“…On the other hand, Pt- or/and Ni-based composite oxide catalysts with a large specific surface area and adjustable acidity have also become a research hotspot in this field; meanwhile, the light alkenes selectivity can be improved by adjusting the acidity and acid sites distribution. − Our group has studied the effects of various composite oxides catalysts, such as Pt/CeO 2 –Al 2 O 3 , Pt/WO 3 –ZrO 2 , Pt/ZrO 2 –TiO 2 , Pt­(MoO 3 )/ZrO 2 –TiO 2 –Al 2 O 3 , − and Pt–Ni/MoO 3 –La 2 O 3 –Al 2 O 3 on the cracking of RP-3 jet fuel and n -decane. Pt-based composite oxides significantly enhanced the heat sink, which is much better than thermal cracking (the highest heat sink is 3.93 MJ/kg at 750 °C), as well as can run stably for 20 min under high temperature, high pressure, and large flow rate conditions (750 °C, 3.5 MPa, 1.0 g/s).…”

“…Pt-based composite oxides significantly enhanced the heat sink, which is much better than thermal cracking (the highest heat sink is 3.93 MJ/kg at 750 °C), as well as can run stably for 20 min under high temperature, high pressure, and large flow rate conditions (750 °C, 3.5 MPa, 1.0 g/s). However, the decrease of available active sites resulting from the sintering of active components under high temperature and carbon deposition coverage is the main reason for the gradual deactivation and stability decline of catalysts. , Therefore, improving the coking inhibition ability of catalysts and preventing the sintering of active components have become the focus of our research in recent years, in order to improve the running time and heat-absorption ability at a high temperature.…”