CHE.09 – HDPE Waste In = Diesel Fuel Out

• Khalfan Almesmari
• Abdullah Amer
• Roxanna Mendoza
• Renata Swarbrick
• Bridget Talbot

Plastic wastes have posed serious threats to the environment, including the decrease of soil nutrient effectiveness and agricultural production as well as emergence of ecological instability. And increasing population leads to an increase in plastic waste, which is a big issue in every country. The dominant plastics produced worldwide are (29.6%) polyethylene, (18.9%) polypropylene, and others with smaller percentage significance. The plastic waste can be managed by landfill and incineration. But the disadvantage of landfills and incineration is carbon dioxide emission. Although plastic waste can be reused and recycled, in the end it will be garbage or become non-recyclable. In order to add value to plastic waste, the conversion of plastic waste to other products has received much attention. In this work, the thermal degradation of high-density polyethylene (HDPE) has been carried out using a fluidized bed reactor. A commercial FCC catalyst based on a zeolite active phase has been used for catalytic pyrolysis of HDPE. We investigated the influence of FCC catalyst, reaction temperatures, and catalyst to plastic ratio. This work also addresses the optimization of catalyst steaming and pyrolysis temperature in order to maximize the production of diesel-oil fraction. Both HDPE primary decomposition and wax cracking reactions take place inside the reactor. Secondary wax and tar reactions are small. The thermal degradation of the material, the product distribution and consequently the economics of the process are strongly influenced by the experimental conditions used. The influence of the operating parameters on the product distribution has been studied using various scientific literature. The catalytic pyrolysis produced liquid and gas fractions comprised of a wide range of hydrocarbons, mainly distributed within C1 to C17. This catalyst gives way to 8 wt% gas yield, 22 wt% medium hydrocarbon (gasoline) fraction, and a yield of 69 wt% C10+ (diesel) fraction. It was found that severe steaming of the catalyst at 816 °C for 8 hours resulted in a higher diesel product composition. In summary for our process, the pyrolysis of 2,000 metric tons of HDPE resulted in 9,916 barrels/day of diesel fraction, 2,798 barrels/day of medium fraction and 165.2 metric tons/day of gases. It can be noted that the results are estimates based on specific experimental data from similar processes in literature. Although there are a few experimental studies concentrated on catalytic pyrolysis of HDPE plastic waste, using theoretical calculation based on Aspen Plus simulation is an essential task. The obtained results can be guidelines in the real operation. A simulation of the whole process can provide the possibility of using this process in a real-world or large-scale application.