Free Resources

Introduction

The thermochemical decomposition of organic materials in the absence of oxygen is termed “Pyrolysis” (Soltes and Elder, 2018). This process allows for normal process conditions including a comparatively low process temperature (Song et al., 2020). It also gives off little or no pollutants into the atmosphere. It involves breaking down polymeric chains into smaller ones in the presence of heat, and occurs during a relatively short period of time (Leng et al., 2019). A notable pyrolysis’ trait is that, new product molecules are formed. These products possess superior properties to the original feedstock (Al-Salem et al., 2017).

Pyrolysis is basically the thermal degradation of residues in the absence of air. It is an endothermic process that gives off products with high calorific values as outputs (Miandad et al., 2019). These products are usually in the forms of liquid (oil), gases that can not be condensed (Methane, Hydrogen, Carbon(IV)oxide, Carbon(II)oxide), and charcoal. The oil is usually extracted after a cooling of the process has taken place (Qureshi et al., 2020).

At around 500?C, the amount of oil that could be extracted from the process is usually around 80-85 wt% (Sharuddin et al., 2017). The process is also quite flexible, as the process conditions could be tweaked to optimize various products’ yields (Fivga and Dmitriou, 2018).  The various products from the pyrolysis process have numerous applications as energy fuels in the industry (Anene et al., 2018).

There are various applications of pyrolysis which include biomass pyrolysis, sludge pyrolysis, plastic pyrolysis, tires and rubber pyrolysis (Auxilio et al., 2017). The oil produced from biomass pyrolysis has received positive notice as a more environmentally friendly fuel because it contributes to reducing the amount of CO₂ in the atmosphere (Sharuddin et al., 2018). Plastic pyrolysis results in greatest production of syngas at high calorific values, which is a key element of efficient waste to energy process aimed at the production of electricity, steam and heat (Mahari et al., 2018).

Plastics play major roles in our daily lives, as they show applications in numerous sectors. This explains the exponential rate in the global production of plastics (Bonten, 2019). Plastics are basically synthetic polymers with the ability of being modified into various strengths and shapes, under the proper thermochemical conditions (majorly heat and pressure). Various plastics have shown significant degrees of plasticity; the properties of materials which imparts them with malleability without breakage (Osswald et al., 2019).

Majority of plastics are usually disposed off after use, this leads to a large accumulation of plastic wastes in the environments and also in the oceans (Phillips, 2017).  As a result of yearly improper disposals of these plastic wastes, the environment suffers from pollution threats (Gallo et al., 2018).

The highest amounts of disposed plastics end up affecting life negatively, while a less significant amount is recycled with the remainder being utilized for energy recovery (Tanaka et al., 2018).

The aforementioned gives an implication that large areas of various geographical regions on earth are littered with plastic wastes (Hurley and Nizzetto, 2018). The retarded degradation rate of plastics also implies that the disposal of plastic wastes intensely impacts the environment negatively (Shafqat et al., 2020).

In order to overcome the concerns faced with environmental pollution, converting the plastic wastes into valuable energy resources which have significant calorific values has been an innovative way to fully utilize the waste in order to satisfy the increased global energy demand (Quesada et al., 2020). This conversion can be made feasible through various innovative thermal treatments technologies such as gasification, pyrolysis, plasma process and incineration (Banu et al., 2020). Among all these technologies, pyrolysis is the most efficient and effective process since the initial large amounts of the waste is significantly reduced, more energy can be recovered from the plastic waste by producing varieties of products, requires lower decomposition temperature and low capital cost (Lee et al., 2021). Pyrolysis brings significantly large values to common materials and waste which makes it an essential process in the global energy industry (Owusu et al., 2018).

Problem statement

Plastics made from materials such as cellulose, coal, natural gas, salt and crude oil through a polymerization or condensation process pose a huge threat to the environment at large as a lot is being produced and used on a daily basis but disposed into the landfills and the ocean body which adversely affects humans and wildlife (Awoyera and Adesina, 2020). Plastics that are pollutants are categorized into micro, meso or macro debris based on size. The chemical structure of plastics however makes them resistant to natural processes of degradation (Ru et al., 2020).

Plastic pollution is a significant global concern that threatens both man and animals – ocean life deterioration and carcinogenic concerns for terrestrial life (Anjana et al., 2020).

Efforts need to be made to curb plastic use and enable its recycling into other more globally tolerable resources in a more renewable and sustainable manner. This would significantly aid in combating water and land pollution (Alabi et al., 2019).

Aim and Objectives

The aim of this study is targeted at deriving an optimum polymer-catalyst ratio in order to obtain a proper selectivity and maximum yield of liquid fuel from the pyrolysis process which would be carried out under optimal process conditions.

These are the objectives;

• Objective 1: Obtaining an optimum yield for the resultant liquid fuel from the pyrolysis process
• Objective  2: Ensuring the pyrolysis process occurs under optimal process conditions.

Research Questions

The identified research questions for this project are provided below:

• How do we carry out the pyrolysis process?
• What is the optimum polymer-catalyst ratio for the optimal selectivity and synthesis of liquid fuel from the pyrolysis process?
• What are the optimum process conditions for the pyrolysis process?

Methodology

This project focuses on secondary research, laboratory experiments and process analysis, and they are discussed below:

Secondary research

The secondary research in this project will utilize a systematic approach (Johnson et al., 2016) to review the works of literature. The steps involved in the systematic review of the literature are provided below:

• Step 1: Identify the research questions that can be used for the project.
• Step 2: Identify the keywords that should be used to research the works of literature.
• Step 3: Extract the journals and books that are appropriate for this project.
• Step 4: Write the literature review chapter.

Laboratory experiments

The laboratory experiments would cover a large chunk of this project. They would be carried out in stages, and as such described below;

• Stage 1:  Sourcing for the required feedstock (plastic wastes), the chosen catalyst and other required raw materials.
• Stage 2:   Characterization of the various feedstock.
• Stage 3:  Developing an appropriate process route and optimal equipment arrangement for an efficient process setup
• Stage 4:  Fabrication of the chosen efficient process route for the production of liquid fuel from the pyrolysis unit by adjusting the factors that influence product yield at optimum process conditions.
• Stage 4:  Carrying out the process reaction.
• Stage 5:  Analyzing the process reaction.
• Stage 6:  Carrying out the phase separation.
• Stage 7:  Characterization of the resultant liquid fuel.
• Stage 8:  Results Testing.

Process Analysis

The totality of the process reaction would be analyzed and this would also occur in stages;

• Stage 1:  Process Testing
• Stage 2:  Process Control
• Stage 3:  Process Optimization

Evaluation

The risk assessment conducted for this project is provided in the table below:

Table 1:  Risk assessment