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A novel industrial cleaning process (DEECOM®, B&M Longworth, Blackburn) hydrolyses polyethylene terephthalate (PET) on contaminated filters using superheated steam at elevated temperature and pressure (300°C and 3 barg). The technology is being adapted to depolymerise waste textiles. This study first involved an assessment of the current large-scale cleaning process’ PET conversion and yield of terephthalic acid (TPA). Then a zinc chloride homogenous catalyst, and, zinc and platinum loaded zeolite beta heterogeneous catalysts, were investigated using a laboratory-scale autoclave reactor to mimic the process. In addition, the industrial waste stream of crude terephthalic acid (TPA) was then purified, repolymerised into PET via the dimethyl terephthalate (DMT) synthesis route, characterised and compared with commercial PET data. Characterisation methods of the repolymerised PET include DSC, TGA, GPC. While still a work in progress, this shows proof-ofconcept in terms of closing the loop and moving to a circular economy. [ABSTRACT FROM AUTHOR]

Light olefins (ethylene and propylene) are essential building blocks of the chemical industry. Fluid catalytic cracking and steam cracking are the key technologies to produce light olefins. However, these technologies can no longer satisfy the current demand for light olefins. Previous studies have found the catalyst formulation (ZY, ZSM-5, and binder) increased production with the most outstanding results using the catalytic cracking process. This study reports catalyst formulations with different loading of ZSM-5 (5%,10%, and 20%). The performance of catalysts were tested in the catalytic cracking of n-heptane as a model compound of light naphtha for the production of light olefins at 500 °C and atmospherical pressure. The results of the tests showed high performance in terms of increased light olefins yield (24 - 64%) and improved C2 and C3 selectivity (35 %) over ZY/ZM/K/B(20:20:30:30) and ZY/ZM/K(20:20:60) with alkene/alkane= ~1.33 and reduction into the amount of undesired C1-C5 alkanes (3%). Therefore, adding ZSM-5 (20%) to catalyst formulation enhances the activity and shape selectivity of the catalytic cracking process onto the catalyst. [ABSTRACT FROM AUTHOR]

Polymers are extremely stable and with rising landfill costs, forthcoming extended producer responsibility tax and the drive towards a circular economy, there is an increasing need to redirect polymer waste from landfill/energy recovery towards enhanced recovery of the raw materials/feedstocks. The COVID pandemic has introduced a significant amount of personal protective equipment (PPE) single use plastics in the form of facemasks into our global ecosystem, which is increasingly becoming an environmental issue due to their increasing non-biodegradability and with declining landfill capacity, this makes plastic recycling a necessity. Chemical recycling stands out as a viable method of converting plastic waste into valuable products, especially liquid fuels (naphtha) and liquefied petroleum gas (LPG). Chemical recycling of plastics can also serve as a route to introduce circularity into the plastic supply chain. This research study is focused on investigating the use of heterogeneous catalysts (zeolites Beta and USY) for the conversion of polypropylene (PP) and single use facemasks into chemical feedstock using hydrocracking. Catalytic hydrocracking reactions were carried out between 270-330 °C at 20 bar hydrogen pressure for 30-60 minutes. The results indicates that USY zeolite was more effective than zeolite beta due to its higher selectivity to liquid products. Moreover, the presence of highly acidic catalysts can be used to suitably recycle polymers into useful hydrocarbons with C3-C16 product distributions. [ABSTRACT FROM AUTHOR]

Membrane surface coatings with 2D materials have been shown to exhibit antifouling properties for water-treatment applications; however, synthesis methods currently based on vacuum filtration are not easily scalable. This study describes a scalable method for coating membranes with a range of 2D materials including graphene oxide (GO), hexagonal boron nitride (hBN), molybdenum disulphide (MoS 2) and tungsten disulphide (WS 2). Isopropyl alcohol solutions containing each class of the 2D flakes were spray-coated onto commercial polyvinylidene fluoride (PVDF) using a pyrolyser. The nanomaterials were secured with polydopamine (PDA) as a crosslinker in a method that could easily be integrated into a scalable roll-to-roll process. Changes in morphology, surface roughness, hydrophobicity, mechanical durability and chemical composition were evaluated using scanning electron microscopy, atomic force microscopy, contact angle, tensile strength measurements and Fourier-transform infrared spectroscopy. The 2D nanomaterials-coated membranes were tested in membrane distillation (MD) experiments over 72 h and compared to pristine PVDF and PDA/PVDF membranes. Salt rejection and MD performance stability were evaluated using feedwaters with high concentrations of humic acid (150 ppm) and paraffin oil (200 ppm) simulating simple organic wastewater from oil and gas extraction. The flux decline ratio was measured in terms of percentage permeate loss per hour (%/h), to allow for future comparisons with studies with different experimental times. The pristine PVDF membrane failed after 10 h by pore-wetting due to fouling while the PDA/PVDF membrane had the largest flux decline ratio (0.3 %/h). The membranes coated with GO and hBN had flux decline ratios orders of magnitude lower (0.0021 ± 0.005 and 0.028 ± 0.01 %/h, respectively). All membranes had a high salt rejection (>99.9 %). The GO-coated membrane was the only membrane type that was able to treat both surfactant-containing and foulant-containing feedwaters. The improved performance is attributed to the decrease in both surface roughness and hydrophobicity, which reduces the adsorption of foulants onto the membrane surface. This work shows a facile, scalable method to overcome fouling limitations in MD. [Display omitted] • 2D flakes were deposited onto porous PVDF membranes via spray coating. • Membrane distillation performance was evaluated for GO, hBN, MoS 2 and WS 2 membranes. • GO and hBN membranes had very low fouling. • Deposition of GO also prevented pore wetting when surfactants were added. [ABSTRACT FROM AUTHOR]