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Biomass-based Fischer–Tropsch paraffin mixtures, having C 16 –C 46 and C 11 –C 45 carbon number range, were hydrocracked over platinum-supported beta, ZSM-5, and mordenite catalysts. The aim of the study was to investigate the effects of the feedstock composition, the process parameters, and the catalyst properties (acidity and zeolite structure) on the C 21 + conversions, the product yields, and the isoparaffin contents. It was stated that lower C 21 + conversions and higher JET and diesel fuel yields can be obtained for feedstock comprising C 11 –C 45 hydrocarbons. Under identical reaction conditions, the activity order of the catalysts was Pt/H-beta > Pt/H-ZSM-5 > Pt/H-mordenite. This order corresponds to the relative number of accessible acid sites. Among the tested catalysts, platinum-supported beta zeolite showed the highest hydroisomerization activity; meanwhile, in the pores of Pt/ZSM-5 and Pt/H-mordenite, diffusion constraints were observed. As the product of hydrocracking valuable gasoline, JET and diesel fuels having high hydrogen content and excellent burning properties were produced.

In this study, pyrolysis of municipal sewage sludge samples from different sources including cattle and chicken manure as well as brook mud, was investigated using a thermogravimetric analysis coupled with a Fourier transform infrared spectrometer (TG-FTIR) at different heating rates (25, 50 and 100 °C/min). In order to determine the kinetic parameters, Arrhenius, model-free Kissinger–Akira–Sunose (KAS), as well as Friedman and Flynn–Wall–Ozawa (FWO) methods were compared. The thermogravimetric results revealed that pyrolysis involved different stages, and that the main decomposition reactions took place in the range of 200–600 °C. In this range, decomposition of biodegradable components (e.g., lipids and polysaccharides), proteins and carbohydrates occurred; meanwhile, there were samples (e.g., cattle manure, brook mud) in which the decomposition step could be observed even at temperatures above 700 °C. According to the Arrhenius method, the activation energies of the first decomposition stage were between 25.6 and 85.4 kJ/mol, while the activation energies of the second and third stages were in the ranges of 11.4–36.3 kJ/mol and 20.2–135 kJ/mol, respectively. The activation energies were also calculated by the KAS, Friedman and FWO methods, which were in the range of 100–300 kJ/mol for municipal sewage sludge or distillery sludge, and ranged between 9.6 and 240 kJ/mol for cattle manure, chicken manure and brook mud samples.

In this study, Fischer-Tropsch paraffin mixture, heavy residue of waste polyethylene pyrolysis, shredded and crashed agricultural polyethylene waste and their combinations were pyrolysed both thermally and catalytically in a two-stage reactor system. During the experimental work, yields and compositions of pyrolysis products were studied as function of feedstock composition and catalyst placement. It was found that the average molecular weight of feedstocks and the presence of ZSM-5 catalyst also have significant effects on the product yields and the compositions. Feedstocks with high concentration of Fischer-Tropsch paraffin and real waste polyethylene resulted in deeper fragmentation in both thermal and thermo-catalytic pyrolysis. Due to the deeper fragmentation, they seemed to be suitable feedstocks for the production of C6-C9 and C10-C14 hydrocarbons. Meanwhile, for production of C15-C21 hydrocarbons, the use of a higher concentration of heavy residue of waste polyethylene pyrolysis in the feedstocks is recommended. From the point of view of liquid hydrocarbon and isomer production, the placement of the catalyst into the 1st reactor proved to be more advantageous. When the catalyst was placed into the 2nd reactor, the product formation shifted to the more volatiles, isomers took part in secondary cracking reactions and aromatics formed in higher concentrations.