Highly efficient catalytic degradation of low-density polyethylene using a novel tungstophosphoric acid/kaolin clay composite catalyst

In order to take advantage of Bronsted acidity of tungstophosphoric acid(TPA) and Lewis acidity of kaolin, TPA loaded kaolin catalysts with varying percentages of TPA (10-50wt%) have been prepared by wet impregnation method. Fourier Transform Infra-Red Spectrometer, X-ray diffractometer, Brunauer-Emmett-Teller surface area analyzer, and Scanning Electron Microscope characterizations were performed to confirm the successful loading of TPA onKaolin. Catalytic cracking of low-density polyethylene (LDPE), by employing our TPA loaded Kaolin as the catalyst, produced a higher percentage of fuel oil (liquid and gaseous hydrocarbons) with negligible amount of semisolid wax (1.0 wt.%), significantly lower compared to the thermal cracking which produced ~22wt.% solid black residue. Moreover, GCMS analysis of oil showed that thermal cracking produces mainly higher hydrocarbons(C22) as compared to the catalytic cracking where larger fraction oflowerhydrocarbons were obtained. We purpose that the higher performance of our catalysts was due to the presence of both Bronsted and Lewis acid sites, which increase their catalytic efficiency and degraded the LDPE at the relatively lower temperatures. Our results suggest that prepared materials were effectivecatalysts with low cost and easily scalable production method; suitable for large-scale highperformance catalytic cracking of LDPE based materials

Synthesis and catalytic performance of cesium and potassium salts of aluminum substituted tungstoborate for pyrolysis of polyethylene waste to petrochemical feedstock

Polyoxometalates have gained considerable attention as a catalyst. Herein, we are reporting tungstoborate based catalysts for the conversion of waste polyethylene to liquid fuel. Novel cesium and potassium salts of aluminum substituted tungstoborate Keggin compounds were synthesized by a simple one-pot method and successfully characterized by FTIR, SEM-EDX, thermal analysis, NMR and single-crystal XRD. Catalytic cracking of waste polyethylene by using our prepared aluminum substituted catalysts (CsAB) showed 97% polymer conversion producing80 wt% of liquid hydrocarbons with a negligible amount of solid residue (∼3 wt%), significantly lower compared to thermal cracking where 22 wt% residue was produced. The oil collected at optimum reaction conditions (0.5 catalyst/polymer ratio and 3 h reaction time) was subjected to GC-MS analysis. The results showed that oil produced in catalytic cracking has a high selectivity to gasoline range hydrocarbons while thermal cracking showed selectivity to higher hydrocarbons (C13–C26). Olefin selectivity was also more prominent in catalytic cracking. Hence cesium and potassium salts of aluminum substituted tungstoborate are excellent catalysts for acid-catalyzed polymer cracking reactions to produce value-added petrochemicals

Highly efficient catalytic pyrolysis of polyethylene waste to derive fuel products by novel polyoxometalate/kaolin composites

This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.We report here alumina-substituted Keggin tungstoborate/kaolin clay composite materials (KAB/kaolin) as polyethylene cracking catalysts. KAB/kaolin composites with varying concentrations of KAB (10–50 wt.%) were synthesized by the wet impregnation method and successfully characterized by Fourier-transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis and scanning electron microscopy with energy dispersive X-ray spectroscopy analytical techniques. Use of KAB loaded kaolin composites as the catalyst for low-density polyethylene (LDPE) cracking exhibited a higher percentage of polymer conversion (99%), producing 84 wt.% of fuel oil and negligible amount (˂ 1 wt.%) of solid residue while thermal cracking produced ~22 wt.% residue. Furthermore, gas chromatography–mass spectrometry analysis of oil obtained by non-catalytic cracking exhibited a high selectivity to high molecular weight hydrocarbons (C13–C23) compared to the catalytic cracking where 70 mol.% of gasoline range hydrocarbons (C5–C12) were produced. We propose that higher cracking ability of our prepared catalysts might ensue from both Brønsted and Lewis acid sites (from KAB and kaolin respectively), which enhanced the yield of liquid fuel products and reduced the cracking temperature of LDPE. These findings suggest that the prepared composites were cost-effective and excellent cracking catalysts that could be recommended for highly efficient conversion of waste plastic materials to petrochemicals at an industrial scale

Fe-POM/ attapulgite composite materials: efficient catalysts for plastic pyrolysis

This article describes the catalytic cracking of low-density polyethylene over attapulgite clay and iron substituted tungstophosphate/attapulgite clay (Fe-POM/attapulgite) composite materials to evaluate their suitability and performance for recycling of plastic waste into liquid fuel. The prepared catalysts enhanced the yield of liquid fuel (hydrocarbons) produced in cracking process. A maximum yield of 82% liquid oil fraction with a negligible amount of coke was obtained for 50% Fe-POM/attapulgite composite. Whereas, only 68% liquid oil fractions with a large amount of solid black residue was produced in case of non-catalytic pyrolysis. Moreover, Fe-POM/attapulgite clay composites showed higher selectivity towards lower hydrocarbons (C5–C12) with aliphatic hydrocarbons as major fractions. These synthesised composite catalysts significantly lowered the pyrolysis temperature from 375°C to 310°C. Hence, recovery of valuable fuel oil from polyethylene using these synthesised catalysts suggested their applicability for energy production from plastic waste at industrial level as well as for effective environment pollution control