Boosting the catalytic performance of metal–zeolite catalysts in the hydrocracking of polyolefin wastes by optimizing the nanoscale proximity

Abstract

Hydrocracking polyolefins using bifunctional metal-zeolite catalysts is a pivotal strategy for catalytic upcycling of plastic waste to produce value-added fuels, while the macro-molecular size and stable C-C bond of polyolefins...

Hierarchical FAU Zeolites Boosting the Hydrocracking of Polyolefin Waste into Liquid Fuels

“…For hexane, all four Y zeolites (Y, Y-M, Y-L, and Y–H) show a similar conversion rate of 6.5 g·g Y –1 ·h –1 . Since hexane has a kinetic diameter smaller than the pore size of Y (0.74 nm), it can readily diffuse into the micropore networks and undergo a cracking reaction. , As the substrate increases to octane, the conversion rate increases as the external and mesoporous surface areas and volumes increase. The rising trend becomes even more pronounced for octadecane and tetracosane, whose kinetic diameters significantly exceed the Y micropore size.…”

“…Notably, the high ratio of isomers to normal alkanes (iso/ n = 4.3) ensures a superior octane number for the produced liquid fuel. , Additional analysis of the liquid product by 1 H NMR and 13 C NMR reveals that it mainly consists of paraffins, while little aromatics and olefins are observed. Moreover, it is also confirmed by gas chromatography–mass spectrometry (GC–MS) that iso -paraffins (with one to three branches) are the dominant composition in the paraffins (Figures S8 and S9), which is consistent with the GC analysis (Figure B) and our previous report …”

“…Moreover, it is also confirmed by gas chromatography−mass spectrometry (GC−MS) that iso-paraffins (with one to three branches) are the dominant composition in the paraffins (Figures S8 and S9), which is consistent with the GC analysis (Figure 4B) and our previous report. 21 3.4. Optimization of Catalyst's Synthesis and Reaction Conditions.…”

“…20 Pt/USY prepared by the colloidimmobilization method with Pt nanoparticles exclusively located on the surface of USY is a superior catalyst compared to its analogues that have Pt inside or away from USY crystalline, reaching a yield of gasoline of over 85%. 21 Catalysts containing 1 wt % Pt deposited on ZSM-5, HY, and HMCM-41 were employed for the hydrocracking of PE, yielding paraffins, olefins, and alkyl aromatics. Notably, catalysts with larger pore structures favored the formation of heavier volatile paraffins, following the trend Pt/HMCM-41 > Pt/HY > Pt/ HZSM-5.…”

“…Zeolites with different pore sizes and topologies were also used for hydrocracking polyolefins in combination with metal, such as ZSM-5, Y, β, and mesoporous zeolites. − A 5 wt % cobalt supported on ZSM-5 catalyzes the solvent-free hydrogenolysis of PE and PP into propane with selectivity in the gas phase over 80 wt % after 20 h at 250 °C and 4 MPa H 2 . Pt/USY prepared by the colloid-immobilization method with Pt nanoparticles exclusively located on the surface of USY is a superior catalyst compared to its analogues that have Pt inside or away from USY crystalline, reaching a yield of gasoline of over 85% . Catalysts containing 1 wt % Pt deposited on ZSM-5, HY, and HMCM-41 were employed for the hydrocracking of PE, yielding paraffins, olefins, and alkyl aromatics.…”