| Abstract | Višeslojna plastična ambalaža sastoji se od dva ili više tipova polimera. Pruža dobra mehanička svojstva uz barijeru protiv vlage, svjetla i kisika kako bi se osigurala duža trajnost proizvoda. Međutim, zbog raznolikosti sastava ambalaže, izazovno je provesti mehaničku ili kemijsku oporabu tih materijala, što rezultira ili njihovim odlaganjem na odlagališta otpada ili zbrinjavanje u postrojenjima za spaljivanje otpada. Piroliza je prepoznata kao alternativna termokemijska tehnologija za oporabu mješovitog plastičnog otpada i polimernih materijala koji su izazovni za proces mehaničkog recikliranja. Stoga se piroliza pojavljuje kao obećavajuća, ekološki prihvatljiva metoda obrade višeslojnoga plastičnog otpada. Glavni produkti pirolize su ulje, plin i ugljenizirani ostatak.
Karakterizacija sastava uzorkovanog višeslojnoga plastičnog otpada (VSPO) provedena je infracrvenom spektroskopijom s Fourierovom transformacijom (FTIR) u sprezi s mikroskopijom. Fizikalno-kemijska svojstva VSPO ispitana su neposrednom (sadržaj vlage, hlapivih tvari i pepela) i posrednom (elementnom analizom te kalorimetrijom). Neizotermna termogravimetrijska analiza je korištena za istraživanje kinetike i mehanizma toplinske razgradnje VSPO. Rezultati dobiveni ovom analizom korišteni su za planiranje radnih uvjeta (temperatura, vrijeme zadržavanja, omjer katalizatora i polimera) u reaktoru za pirolizu u laboratorijskom mjerilu. Provedena je eksperimentalna valorizacija VSPO u pirolitičkom laboratorijskom reaktoru s upotrebom i bez upotrebe katalizatora te je napravljena analiza dobivenih produkata. Analitičke metode korištene za analizu produkata su infracrvena spektroskopija s Fourierovom transformacijom, nuklearna magnetska rezonancija (NMR), plinska kromatografija sa spektrometrom masa (GC-MS) i kalorimetrija. Rezultati NMR analize su pokazali kako svi uzorci u većinskom udjelu sadrže alifatske ugljikovodike (alkane i alkene), zatim aromatske ugljikovodike te u manjem udjelu aldehide, vinil i -OH skupine što se slaže s rezultatima FTIR analize. GC-MS analizom je potvrđeno uklanjanje spojeva s kisikom koji nisu poželjni u gorivima u uzorcima dobivenim s katalizatorom. Kalorimetrijska analiza je pokazala da pirolitički produkti imaju relativno visoku gornju ogrjevnu vrijednost, od 45,2 MJ kg-1 do 46,8 MJ kg-1. Provedena je tehno-ekonomska analiza idejnog rješenja pirolitičkog postrojenja te se investicija pokazala isplativom, što je vidljivo iz dobivene vrijednosti interne stope povrata koja je iznosila 15,54% nakon provedene analize. |
| Abstract (english) | Multi-layered plastic packaging consists of two or more types of polymers. It provides good mechanical properties with barriers against humidity, light and oxygen to ensure a longer shelf life of the products. However, due to a variety in packaging composition, it is challenging to perform mechanical or chemical recycling of these materials, which leads to landfill or incineration plant. Pyrolysis has been found as an alternative thermochemical recovery technology for mixed plastic waste and polymer materials that are challenging for recycling. Therefore, pyrolysis arises as a promising, environmentally friendly method of multi-layered plastic waste (MPW) treatment. Main products of pyrolysis are oil, gas and char, which can be further used to produce fuels, energy and chemicals.
The composition characterization of sampled MPW was conducted using Fourier-transform infrared spectroscopy (FTIR) coupled with microscopy. The physicochemical properties of MPW were examined through proximate (moisture content, volatile matter, and ash content) and ultimate (elemental) analysis, as well as calorimetry. Non-isothermal thermogravimetric analysis was used to investigate the kinetics and mechanism of thermal degradation of MPW. The results obtained from this analysis were used to plan operational conditions (temperature, residence time, catalyst-to-polymer ratio) in a pilot-scale pyrolysis reactor. Experimental valorization of MPW was carried out in a pyrolytic laboratory reactor, both with and without catalyst usage, followed by analysis of the obtained products. Analytical methods employed for product analysis included Fourier-transform infrared spectroscopy, nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and calorimetry. NMR analysis results indicated that the majority of the samples consisted of aliphatic hydrocarbons (alkanes and alkenes), followed by aromatic hydrocarbons, and in smaller proportions, aldehydes, vinyl groups, and -OH groups, consistent with FTIR results. GC-MS analysis of catalyst-treated samples confirmed the removal of oxygenated compounds that are undesirable in fuels. Calorimetric analysis demonstrated that pyrolytic products possessed relatively high higher heating values, ranging from 45.2 MJ kg-1 to 46.8 MJ kg-1. A techno-economic analysis of the conceptual pyrolysis plant solution for the selected real-world case study revealed the investment to be cost-effective, as evidenced by the obtained internal rate of return value, which was 15.54% after the analysis. |
