Enhancing the performance of a PtPd/HY catalyst for HDPE/VGO hydrocracking through zeolite desilication. (1st December 2022)

• Record Type: Journal Article
• Authors: Vela, Francisco J.; Palos, Roberto; García, Juan Rafael; Sedran, Ulises; Bilbao, Javier; Arandes, José M.; Gutiérrez, Alazne
• Is Part Of: Fuel. Volume 329(2022)
• Publication Date: 2022-12-01
• Subjects: Hydrocracking -- Fuels -- Waste plastic -- Waste refinery -- Desilication -- Hierarchical structure; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.125392
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Pt-Pd catalysts supported desilicated HY zeolite were prepared. Desilication created mesopores at the same time that decreased acidity. Overcracking reactions were attenuated increasing the yield of naphtha. The formation of coke fractions was inhibited with desilicated catalysts. Abstract: The valorization of post-consumer waste plastic in a refinery is an attractive initiative to avoid environmental problems caused by the poor plastic waste management. The modification of a bifunctional PtPd/HY catalyst through desilication (using NaOH) of the ultrastable HY zeolite has been carried out to upgrade waste plastic (high-density polyethylene (HDPE)) dissolved in a secondary refinery stream (vacuum gas oil (VGO)) through hydrocracking. Three different catalysts have been studied: the parent (Cat-A), undergoing a desilication cycle (Cat-B), and subjected to two cycles of desilication (Cat-C). The characterization techniques employed have been: N2 adsorption–desorption, TEM, ICP-AES, tert- butylamine-TPD, pyridine FTIR, WDXRF, XRD and TPO. The hydrocracking tests have been carried out in a semi-batch reactor at: 440 °C; 80 bar; catalyst to feed ratio, 0.1 gcat (gfeed ) –1 ; HDPE to feed ratio, 0.2 gHDPE (gfeed ) –1 ; and reaction time, 2 h. The products have been fractioned according to their boiling point range in: gas, naphtha, light cycle oil, heavy cycle oil and coke. The composition of each fraction has been determined in terms of concentration of paraffins, olefins, naphthenes and (mono-, di- and poly-) aromatics. The results show that alkaline treated catalysts enhance the fuel production, with high HDPE and HCO conversions. The Cat-C (the one submitted to two desilication cycles) has displayed the greatest performance, reducing by half the gas yield and increasing the naphtha yield by 51 wt% respect to those obtained with the parent catalyst (Cat-A). Moreover, it has decreased the coke deposition and the coke formed has been less developed.