Catalytic pyrolysis of waste polypropylene using Ahoko kaolin from Nigeria

Abstract

The aim of this study is to convert polypropylene waste into usable liquid fuel via pyrolysis technique using kaolin as a low-cost catalyst. Waste polypropylene was thermally and catalytically degraded in a chemical vapour deposition (CVD) horizontal glass reactor at a temperature of 450 °C, residence time of 30 min, and heating rate of 30 °C/min. The kaolin clay was characterized by XRF analysis while the ultimate and proximate analysis of the polypropylene feed carried out gave combustible materials content of 93.77 wt%, fixed carbon of 1.62 wt%, calorific value of 45.20 MJ/kg and elemental composition with carbon (83.65%), hydrogen (14.27%), oxygen (0.15%), sulphur (0.1%), chlorine (1.16%), and nitrogen (0.67%). Thermal cracking was carried out in the absence of catalyst and the process gave a yield of liquid, gaseous, and solid products of 67.48, 8.85, and 23.67 wt%, respectively. Furthermore, kaolin clay was employed as a catalyst in catalytic pyrolysis of the same feedstock for catalyst-to-plastic ratio of 1:1, 1:2, 1:3, and 1:4 at the same operating parameters as in thermal cracking. Optimum yield was obtained at a catalyst-to-plastic ratio of 1:3 with a yield of 79.85, 1.48, and 18.67 wt% for liquid, gaseous, and solid products, respectively. The liquid products obtained for both thermal and catalytic cracking at optimum conditions were characterized for their suitability as fuel. The properties determined were density, viscosity, flash point, fire point, pour point, and calorific value. The results suggest that catalytic pyrolysis produced liquid products, whose properties are comparable to conventional fuels (gasoline and diesel oil) than that produced through thermal pyrolysis. FTIR analysis of the liquid product from catalytic pyrolysis also shows that it contains hydrocarbons with different functional groups such as aromatics, olefins, carbonyl, amines, sulphides, and hydroxyl.

Catalytic Pyrolysis of a Residual Plastic Waste Using Zeolites Produced by Coal Fly Ash

“…Taking into account that CFA has a null cost and it is used without any preliminary treatment, it seems a suitable catalytic material, especially if compared to NaX/CFA. CFA composition causes a good cracking effect, as it was also observed by other authors with different materials, containing a significant amount of silica and alumina species and other metal oxides, e.g., Fe 2 O 3 [16,36]. Benedetti et al [39] found a noticeable improvement in the production of oil to the detriment of tar.…”

“…Catalysts 2020, 10, 1113 4 of 16 DSC experiments of all the samples were carried out simultaneously with TG ones. As observed for the degradation temperatures, significant differences were observed only for HX/CFA (Table 1), where the use of the catalyst induces a remarkable decrease in the decomposition heat (Q d ).…”

“…In particular, the introduction of acid zeolites during pyrolysis of polyolefins has been related to an increase of oil and gas production [13,14] and a decrease of degradation temperature [15]. Despite these technical advantages, these synthetic catalysts come with high cost of production, thus making catalytic cracking relatively expensive [16]. Furthermore, they have a relatively short life in the pyrolysis process, meaning that the economics of the process also depend on proper regeneration of the catalyst for its reuse [17].…”

Plastic wastes: environmental hazard and instrument for wealth creation in Nigeria

“…Also, leachates from landfills contains heavy metals including lead, cadmium, mercury, pesticides, disinfectants, pharmaceutical wastes, organics and chemicals substances that could contaminate the groundwater. While mixture of toxic substances and decomposing organic matter from landfill sites could also alter the structure and texture of soils, hence hindering good agricultural practices and subsequently impact negatively on biodiversity [20].…”

A Review Paper on Utilisation of used PPE Kits in a Sustainable Way

“…They conducted this experiment in various ratios of catalyst: polypropylene starting with 1:1 till 1:20 but the effect of catalyst was only pronounced till the ratio 1:4 and after that effect was almost negligible on the yield obtained. The yields obtained in the different states of 1:1, 1;2, 1:3 and 1:4 ratios are shown below in the pie chart [12]. The highest yield of liquid which is most useful as a biofuel is obtained in the ratio 1:3.SO, we concluded that the ratio 1:3 is the most useful ratio.…”