Catalytic co-pyrolysis of oil sludge with HDPE to obtain paraffinic products over HUSY zeolites prepared by dealumination and desilication

[Display omitted] •The performance of Y zeolites on co-pyrolysis of oil sludge with HDPE has been investigated.•Modified zeolites promote the generation of diesel oil fraction rich on paraffines.•Textural and acidic properties of zeolites have been the main parameters of oil quality. Oil sludge is a waste from the oil industry with a complex composition and its treatment is still a challenge. In addition, polyolefin waste is becoming a problem due to its accumulation and slow degradation. In this study, catalytic co-pyrolysis was used to treat oil sludge and high density polyethylene (HDPE) at 450 °C and at an atmospheric pressure for 15 min to generate paraffin-rich oily products. Y zeolites were obtained by dealumination and desilication processes which were characterized by XRD, N2 adsorption, FTIR, 29Si and 27Al NMR, TG and NH3 TPD. Pristine and modified zeolites were evaluated in the co-pyrolysis in order to assess their performances through the quality of the obtained pyrolytic oil (GC–MS and SimDis). The modificated zeolites presented higher mesoporosity than the original solid as so lower total acidity. Amidst the tested catalysts, Mod-Si-10 and Mod-Al presented the best performances showing high yield of liquid fraction, rich in parafinic light hydrocarbons, probably due to their moderate acidity and improved mesoporosity. Consequently, these two zeolites presented outstanding catalytic characteristics alongside high selectivity to paraffinic hydrocarbons in the diesel fraction from co-pyrolisis of the oil sludge waste with HDPE.