ENGR339:Team03

Team 03: Process Design for Diesel Fuel Production

from Waste Plastic via Pyrolysis

Project Proposal and Feasibility Study

Jacob Dornan, ChE

YoungJae Jo, ChE

David Wierenga, ChE

ENGR 339: Senior Design

12/12/16

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Executive Summary

This report entails a feasibility study in the production of diesel fuel derived from waste plastic. waste

plastic comes from a variety of sources and is plentiful and inexpensive. There are more than 33 million

tons of plastic discarded each year in the US; only 7% is recycled and 8% is combusted for energy; The

rest of the waste plastic is put into landfills or makes its way into the oceans. This means that about 25

million tons of plastic reaches the end of its life after single use, which is a waste of resources [1]. Our

project intends to address the issue of plastic waste by extending its life by depolymerizing plastic to

diesel fuel.

The conversion of waste plastic into fuel is a process that is not widely used on an industrial scale yet

there are several companies that are using this technology commercially. One of the processes available

to convert waste plastic into fuel is called pyrolysis, which uses high heat to decompose polymers. In the

case of synthetic polymers, the feed is typically heated to 400-500°C in the absence of oxygen. The high

heat will cause the polymer chains to break into smaller carbon chains of varying length.

The chemical reactions involved in pyrolysis are not well-defined because multiple reactions occur

randomly depending on the feed composition. However, some kinetic data for the pyrolysis of an

equimolar mixture of polypropylene, polyethylene, and polystyrene was available to model our reaction.

The use of catalysts will also be considered.

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Table of Contents

Executive Summary………………………………………………………………………………………...2

Table of Contents…………………………………………………………………………………………...3

1. Introduction……………………………………………………………………………………......5

1.1 Project Description…………………………………………………………………….…...5

1.1.1 Problem Definition……………………………………………………………...5

1.1.2 Solution to Problem…………………………………………………………….5

1.1.3 Market Analysis……………………………………………………...…………5

1.1.4 Scope of Project………………………………………………………………...6

1.1.5 Project Proposal………………………………………………………………...6

1.2 Team Members and Advisors……………………………………………………………...6

1.2.1 Jacob Dornan – Member………………………………………………………..6

1.2.2 YoungJae Jo – Member………………………………………………………...6

1.2.3 David Wierenga - Member……………………………………………………..7

1.2.4 Prof. VanAntwerp - Advisor…..……………………………………………….7

1.2.5 Sam Cooper - Industrial Mentor………………………………………..............7

1.2.6 Calvin College Engineering…………………………………………………….7

2. Project Management……………………………………………………………………………….8

2.1 Team Organization………………………………………………………………...............8

2.2 Schedule……………………………………………………………………………………8

2.3 Budget……………………………………………………………………………...............9

2.4 Method of Approach…………………………………………………………….................9

3. Research Review…………………………………………………………………………………...9

3.1 Introduction.……………………………………………………………………………....9

3.2 Thermal Pyrolysis………………………………………………………………………..10

3.3 Catalytic Pyrolysis……………………………………………………………………….11

3.4 Summary………………………………………………………………………................13

4. Background…………………………………………………………………………..…………...14

4.1 Plastics………….………………………………………………………………………,..14

4.2 Plastic Recycling…………………………………………………………………………15

4.2.1 Conventional Methods of Plastic Recycling………………………………….15

4.2.2 Limitations to Plastic Recycling……………………………………………....15

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4.3 Properties of Conventional Diesel Fuel………...………………………………………...15

4.3.1 Introduction……………………………………………………………………15

4.3.2 No. 2 Diesel Fuel……………………………………………………………...16

4.3.3 No. 1 Diesel Fuel……………………………………………………………...16

4.3.4 Properties of Diesel Fuel………………………………………………………17

4.3.5 Diesel Derived from the Pyrolysis of Plastic Polymers……………………….18

5. Design Variables…………………………………………………………………………………..19

6. Design Norms……………………………………………………………………………………..19

7. Conclusion.......................................................................................................................................20

8. Citations…………………………………………………………………………………………...22

9. List of Figures……………………………………………………………………………………..25

10. List of Tables……………………………………………………………………………………...30

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1. Introduction

1.1 Project Description

Annual diesel fuel consumption in the US amounts to over 60 billion gallons [2] and is projected to increase

by 29 million gallons per day over the next 25 years [3]. Diesel fuel is traditionally produced by the refining

of crude oil, however, several alternative feed stocks have been investigated in recent years including

biomass [4], coal [5], algae [6] and waste plastic [7]. The use of waste plastic as a feed stock is of particular

interest due to its additional utility as a method of recycling plastic. There are two primary methods

currently under investigation for converting plastic into diesel fuel; gasification and pyrolysis. The

gasification of waste plastic produces a syn-gas that can be converted into a fuel oil via the Fischer-Tropsch

process [8]. Pyrolysis of waste plastic yields gas, oil and char products. The oil product is then further

refined into a liquid fuel [9]. The design of a commercial scale plant using pyrolysis to convert waste plastic

in to diesel fuel is the goal team 3. The feasibility of this design is reported herein.

1.1.1 Problem Definition

Plastic waste poses a huge environmental risk, especially in an age when most products are packaged with

plastic. In 2014, annual production of plastic in the United States reached 33.25 million tons, of which,

75.5% was returned to landfills. [1] This is a tremendous waste of resources since plastics have a heating

value comparable to that of many fossil fuels and could be very valuable if converted into a usable form.

1.1.2 Solution to Problem

The lifetime of non-recycled plastics can be extended by converting plastics to fuel. Our group will be

investigating the feasibility of catalytic pyrolysis as a method of decomposing plastics into an oil that

could be refined into a liquid fuel. Catalytic pyrolysis produces three products, a light gas, an oil, and a

char. A portion of the energy required to operate this plant can be made up by combusting the light gasses

to heat the reactor. Ultimately, plastic is kept from entering landfills and a useful commodity is produced

in the meantime.

1.1.3 Market Analysis

The project is primarily focused towards the design of the processes required to produce diesel fuel from

plastic using catalytic pyrolysis. This process is designed to be capable of operating all year. The process

will be designed to be a flow system. The feed, waste plastic, will be sourced from waste management

facilities and landfills which are readily available anywhere in continental US. The process is not meant to

be implemented in an independent manner because economies of scale suggests the plant will not be cost

efficient. The processing plant must either be subsidized by the government or implemented on an

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existing fuel refinery for oil companies that seek to produce fuel in a more environmentally conscious

manner.

1.1.4 Scope of Project

The project is mainly concerned with the design of pyrolyzing plastics to fuel. We will be focusing on

designing the reactor and subsequent separation and purification processes. Designing the reactor will

focus on defining the feed stream and reaction conditions such as temperature and the presence of

catalyst. Separation and purification processes will involve designing a flash separation tank to separate

the gaseous products and liquid products. A series of distillation columns will also to be designed to

purify the liquid products to diesel fuel.

1.1.5 Project Proposal

We propose to design a process for the production of diesel fuel from waste plastic in a continuous reactor

with a target production rate of 1 billion gallons of diesel fuel per year. The design will include a design

of the reactor, the distillation column and the flow systems contained therein as well as a cost analysis of

these components and the material consumed and produced in the system. For this project to be deemed

feasible it must be able to annually produce a billion gallons of diesel fuel under constraints of cost to run

and a standard payback cost to build the plant.

1.2 Team Members and Advisors

1.2.1 Jacob Dornan (Member)

Jacob Dornan is Chemical Engineering student at Calvin College. He has interned at two companies not

far from his home in Rockford, MI. Throughout 2015 he interned at Kellogg Company’s Grand Rapids

Pop Tart plant and during the summer of 2016 at Amway Corporation world headquarters in Ada, MI.

He spends most of his free time invested in restoring his 1967 Jeep Super Wagoneer and woodworking

with his father.

1.2.2 YoungJae Jo (Member)

Young Jae is a chemical engineering student at Calvin College. He has had an internship in Boehringer-

Ingelheim Co. KG, a pharmaceutical company, at the German headquarters during the summer of 2016

focusing on scale-up and process development. He enjoys traveling during his free time—most likely

influenced by growing up in Korea, Ethiopia, Turkey, and Canada.

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1.2.3 David Wierenga (Member)

David Wierenga is a chemical engineering student at Calvin College. He has three years of experience as

a certified welder and pipe fitter serving the agricultural industry near his home in Central California. He

also has two years of organic chemistry research experience, gained while working in the Calvin College

Chemistry department.

1.2.4 Jeremy vanAntwerp (Advisor)

Jeremy VanAntwerp is a Professor of Engineering at Calvin College who teaches introduction to

thermodynamics, fluid dynamics and heat transfer, control systems engineering, and senior design. He is

on the editorial board for the IEEE Control Systems Magazine and has several publications of his own.

He holds a United States Patent and is passionate about helping students understand Engineering through

hands on engagement and a Christian mindset. Most importantly (to Team 3) he is our Advisor for Sr.

Design.

1.2.5 Sam Cooper (Industrial Mentor)

Sam Cooper serves at the Team’s Industrial Mentor. He is a Calvin graduate who started his career with

Siemens Oil and Gas in Houston, TX. He is currently living in Chicago and loves hunting and shooting

shotguns on his farm in Rockford, MI.

1.2.6 Calvin College Engineering Program

Calvin College offers undergraduate programs in engineering. Students who complete the requirements will

earn their BSE in Engineering with one of four concentrations: Chemical, Civil and environmental,

Mechanical, or Electrical and computer. The Calvin College Engineering program is ABET (Accreditation

Board for Engineering and Technology) certified.

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2 Project Management

To successfully complete any project, time management and team management is key. Weekly meetings

are held with the team’s advisor, Jeremy VanAntwerp to ensure good progress is being made and that the

project remains on track. Alignment between team and advisor is always good and this time is never

taken for granted. In addition to team/advisor meetings there were also weekly team meetings to ensure

all team mates understood his individual duties.

2.1 Team Organization

Each member of Team 3: Plastic Power has specific roles responsible. The technical work of the project

remains a team endeavor but each member has an area they are primarily responsible for.

Jacob Dornan:

Jacob is the teams Webmaster and is responsible for the upkeep of the team’s website. In addition to

Webmaster he is responsible for keeping the team moving forward and ensuring that important deadlines

are met.

YoungJae Jo:

Young Jae is the UNISIM guru and leads the team through the many complications of this great design

software. He also ensures enough research is done on a matter to ensure sufficient understanding of the

idea or operation at hand.

David Wierenga:

David leads the team meetings and is responsible for all communication on behalf of the team. David is

also responsible for documenting and managing all the research done by the team.

2.2 Schedule

A work breakdown schedule is used to document the tasks and deadlines that are pertinent to the team. It

is accessible to every member of the team via Microsoft OneDrive so that it can be continually edited by

each member to reflect the most recent change in scheduling. Microsoft Outlook is the basis for

scheduling and communication within the team.

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2.3 Budget

The team project budget will likely remain untouched as the team is developing a theoretical design of a

process in the production of diesel fuel and is not physically creating or purchasing a reactor or even a

single separation column.

2.4 Method of Approach.

Each team member has specific duties. Each team member whose duties do not fall within a certain area

are not exempt from that work and therefore each team member will in some way be tied to each and

every part of the project. Each team member will lead the others when work is performed in his area of

guidance but overall each member will participate in all aspects of the project. Out of the required work

research needs to be performed first, after enough understanding of the process is attained the reactor will

be designed. The design of a reactor is one of the two major requirements of a chemical engineering

design project. After the reactor is designed we will have a specific product stream and a separation will

be required. Separations is the other requirement of any chemical engineering design project. Once the

separations are determined an economic analysis of the project. To ensure an organized approach to the

project each team member will work together in the completion of all 4 of these major parts of the project.

3.0 Research Review

3.1 Introduction

To proceed with a discussion of the research behind this study, a few terms and concepts must first be

addressed, starting with pyrolysis. Pyrolysis is broadly defined as a chemical decomposition initiated by

high temperature. This is often described as thermal decomposition, thermal degradation, or thermal

cracking. The first two terms, while often used interchangeably, are not the same and an important

distinction must be made to avoid confusion. The ASTM definitions will be followed in this report

regarding decomposition and degradation. Thermal decomposition “is a process of extensive chemical

species change caused by heat”. [10] [11] Thermal degradation is “a process whereby the action of heat or

elevated temperature on a material, product, or assembly causes a loss of physical, mechanical, or

electrical properties”. [10] [11] In the case of polymer pyrolysis, plastic is first melted and then continues

to decompose into monomers and oligomers of varying length. These products are the result of C-C bond

scission that takes place along the length of polymer chains and can occur via 4 mechanisms, as shown in

fig. 1. Bond scission can occur along the main chain of a polymer or within a side chain, either at the end

producing a monomer, or in the middle producing an oligomer. These mechanisms all depend on the

formation of a free radical to initiate the reaction, figure 2. The distribution of these mechanisms is highly

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dependent on the structure of the polymer and, along with temperature, determines the relative yields of

gas, oil, and char products, Table. 1.

3.2 Thermal Pyrolysis

The use of pyrolysis in the production of diesel fuel from waste plastic can be divided into two general

categories; thermal and catalytic [9]. Thermal pyrolysis relies solely on heat to provide the energy for C-C

bond scission and is an endothermic reaction. This method has been studied extensively and has proven to

be effective in producing relatively high yields of the oil product, using primarily polypropylene (PP),

high density polyethylene (HDPE), low density polyethylene (LDPE), and polystyrene (PS) as feed stocks

[9]. As a point of reference, complete thermal pyrolysis of PP and PE occurs at temperatures exceeding

700°C, yielding primarily light gases of C1-C4 and simple aromatic compounds (benzene, toluene,

xylene). The low thermal conductivity of plastics, in addition to the endothermic nature of the desired

reactions, would require a tremendous amount of energy to sustain reactor conditions at 700°C or more.

Therefore, research into the production of fuel from waste plastic is primarily focused on milder reaction

conditions (400°C to 550°C) where the products are distributed between gas, oil and char fractions.

The effect of temperature on the yield of these products is discussed below.

In 2009, Onwudili, Insura, and Williams published a comprehensive summary of the thermal pyrolysis of

PS and LDPE, including temperature and residence time effects in a batch reactor [12]. They observed

that PS completely decomposed into char, oil, and gas products at 350°C. At this temperature, the

resulting oil accounted for 98 wt.% of the total plastic feed, while the gas and char products represented

only 2 wt.%. Their preliminary studies ranged from 350°C - 500°C and reflected a negligible increase in

the production of light gases over this temperature range. The oil and char products, however, changed

significantly starting at about 450°C. It was observed that after 450°C, the quantity of oil reduced

dramatically in favor of the char. Unfortunately, this reduction in the oil product did not come at an

appreciable increase in the quality of the oil, table 2. At 500°C, thermal pyrolysis of PS resulted in yields

of about 2.5 wt.% gas, 67 wt.% oil, and 30.5 wt.% char. The optimal case for thermal pyrolysis of PS

occurred at 400°C. Williams includes a residence time study at this temperature. This study indicates that

increased residence time allows the styrene monomer that to react into toluene, ethylbenzene, and

cumene, table 3.

This same study conducted by Onwudili, Insura, and Williams also included data on LDPE. They report

the minimum temperature for complete decomposition of LDPE to be 425°C, producing 10wt.% gas, 89.5

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wt.% oil, and negligible char. As temperature increased, secondary reactions caused a portion of

condensable compounds to crack into light gases, reducing the yield of oil and increasing the gas

production. Measurable char formation occurred at 450°C with yields of 25 wt% gas, 72.4 wt% oil, and

1.75 wt% char. Further increase in temperature continued to favor the formation of char and gas at the

expense of oil. Additionally, as temperature increased, the aliphatic nature of the oil shifted dramatically

to a primarily aromatic nature, table 4. A residence time study, performed at 450°C, illustrated the same

trend favoring formation of aromatic compounds at longer residence times, table 5, [12]. The dependence

of oil yield on reactor temperature is confirmed by many other studies, including that of van Grieken,

Serrano, Aguado, Garcia, and Rojo in 2001, figure 3 [13].

These results are consistent with a similar study published by Marcilla, Beltran and Navarro in 2009,

investigating the composition of products that result from the thermal pyrolysis of LDPE and HDPE [14].

This study reports the highest combined yields of both gas and oil products at temperatures between

469°C and 494°C for LDPE and between 490°C and 515°C for HDPE. This difference is likely due to the

greater degree of branching in LDPE compared to HDPE. This branching favors the formation of free

radicals (which are necessary for any of the bond scission mechanisms, figure 2) and accounts for the

lower thermal stability observed in LDPE relative to HDPE [15]. However, since the chemical formulas

of the HDPE and LDPE are identical, the composition of the oil and gas produced from their thermal

pyrolysis is also nearly identical and, for the purposes of this report, will be considered interchangeable

[14].

Thermal pyrolysis can be optimized to produce oil with yields exceeding 80%, at operating temperatures

around 400°C to 450°C. However, thermal decomposition occurs via radical mechanisms causing C-C

bond scission to take place at random along the length of a polymer chain. The resulting oil has a broadly

defined composition with a wide distribution in the number carbon atoms in the main chain of each

compound. Processing this oil into a fuel exhibiting the properties required by ASTM D975-16 for diesel

fuel would require extensive separation and refining.

3.3 Catalytic pyrolysis

The use of a catalyst in the pyrolysis of polymers offers three main advantages; tailorable selectivity of

the oil composition, sequestration of hetero-atoms from oil products, and increased rate of polymer chain

cracking, and therefore, reduced retention time. The catalysts used in this process are all acid catalysts

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and are of two main types; FCC catalysts and alumina-silica catalysts. Alumina-silica catalysts can be

amorphous or crystalline. Crystalline alumina-silica is known as Zeolite.

FCC, or fluidized catalytic cracking, catalysts are ubiquitous in petroleum refining and are used to crack

heavy components present in crude oil into smaller hydrocarbons suitable for producing gasoline and

diesel fuel. In general, FCC catalysts are made up of a matrix, a binder, a filler, and the active zeolite. The

matrix is the catalyst support unto which the binder, filler and zeolite are fixed. Amorphous alumina-silica

(Al2O3 SiO2) is typically used when an active matrix is required. An active matrix (compared to an

inactive matrix) is particularly important when long hydrocarbon chains are unable to diffuse into the

inner pores of the catalyst due to steric bulk. The surface if this amorphous catalyst contains both Lewis

acids sites that serve as proton acceptors, and Bronsted acid sites that provide a source of ionizable

hydrogen atoms. These acidic sites serve as the primary cracking sites. This allows large molecules near

the surface of the catalyst to be cracked into smaller molecules that can diffuse into the catalyst itself. The

filler and the binder are simply there to add physical integrity to the catalyst. The filler is almost always

kaolin clay while typical binders include silica sol and aluminum chlorhydrol. Zeolite is a porous and

crystalline alumina-silica (Al2O3-SiO2) mineral and the most active component of FCC catalysts.

Synthetic zeolites with varying crystalline structures are produced for a wide range of applications.

Synthetic zeolites also vary in their silica-alumina ratio, which alters the surface acidity. The two primary

types of zeolite used in FCC catalysts are Y-zeolite and X-zeolite. They have the same structure but

slightly different silica-alumina ratios. This ratio determines the surface acidity of the catalyst, and

therefore, it’s reactivity. When used in petroleum cat-crackers, the pores of FCC catalysts become

clogged with coke in less than one minute before having requiring regenerated under high heat. The

number of regeneration cycles a FCC catalyst pellet can endure is limited, and eventually it its utility in a

cat cracker is completely lost. [16] [17]

The FCC catalysts used in the pyrolysis of waste plastic are in fact spent cat-cracker catalysts from

petroleum refineries. In addition to being a cost-effective method of producing high quality pyrolysis oil,

the use of spent FCC catalyst has also proven to be very effective at increasing the yield of liquid oil. [18]

It has been shown that the optimal ratio for oil production using FCC catalysts is a 20 wt.%

catalyst/polymer ratio [19]. Furthermore, a series of reactions carried out by [20] illustrates the effects of

higher catalysts ration. All reactions in this study were carried out using 50/50 wt. ratio of spent FCC

catalyst to polymer. This study produced consistently high purity oils with minimal gas formation,

however, there is a significant reduction of liquid oil yield for these conditions. The results of these trials

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are summarized in tables 6,7, and 8. At catalyst ratios closer to the optimal 20 wt%, catalytic pyrolysis of

LDPE, HDPE, PP, and PS using FCC catalysts have resulted in oil yields between 80 – 90 wt% [21].

The second variety of catalysts under consideration are alumina-silica based. Amorphous alumina-silica is

the same compound used for the matrix in FCC catalysts, while crystalline Zeolite comprises the highly

actives site within FCC catalyst particles. As in an FCC matrix, the silica-alumina ratio determines the

surface acidity of the catalyst; this holds for both amorphous alumina–silica catalysts and zeolites. As the

surface acidity of the catalyst increases, so does the rate of polymer decomposition. Catalysts that are too

acidic will “over-crack” polymer chains producing high yields of light gases and very little oil. Therefore,

peak yield of liquid oil occurs at the optimal combination of surface acidity, operating temperature, and

residence time. [9] This point has been clearly illustrated in [22] through catalytic pyrolysis of HDPE

using SA-2 (amorphous catalyst) along-side ZSM-5 (synthetic crystalline zeolite with higher acidity). The

resulting oil was produced in 74.3 wt.% and 49.8 wt% yields respectively. Additionally, pyrolysis of PP

and HDPE was optimized at 500°C in a fluidized bed using the same alumina-silica catalyst. these

conditions produced oil yields of 90% and 85% for PP and HDPE respectively. [23]

3.3 Research Summary

Pyrolysis of plastics can be divided into two general methods, thermal and catalytic pyrolysis. Thermal

pyrolysis can produce very high yields of oil for a wide range of feed plastic, and relies only on heat to

initiate bond scission. These bond scission reactions occur via radical mechanisms and result in a broad

distribution of the length of carbon chains found in the oil produced using this method. Alternatively, acid

catalyzed pyrolysis using FCC, zeolite, or amorphous alumina-silica catalysts, can be used to increase the

selectivity of polymer chain cracking reactions. Catalysts with moderate to low surface acidity are allow

for high yields of oil and limited gas formation.

The chemistry described in the research articles summarized above all takes place in the liquid phase and

the catalysts are in direct contact with the charge of melted plastic. This works fine as a method of

collecting reaction data, but a continuous process must have a different method of contacting polymer

constituents with the catalyst to prevent catalyst fouling. Most recently, research in this field has focused

on the use of fractionating towers for catalytic pyrolysis of plastics. This is a two-stage process where

plastic is charged to a stirred reaction vessel and initially undergoes thermal pyrolysis. The gas and vapor

produced from this process is then passed over a catalyst bed to reform compounds that are shorter than

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desired and crack molecules that are longer than desired. [24] [25] The general approach of this process

will serve as a starting point during the design phase in the spring semester.

4.0 Background

4.1 Plastics

Synthetic plastics comprise most materials we use in our lives—anything from Lego blocks we used to

play as children to the fabric used for spacesuits. There are two main categories of synthetics plastics:

thermosets and thermoplastics. Both thermosets and thermoplastics are molded initially. However,

thermosets cannot be remolded as the crosslinks in thermosets are irreversible. Thermoplastics, on the

other hand, can be remolded as heat will soften the polymer. Most commonly used plastics are all

thermoplastics which include polyethylene terephthalate (PET), high density and low density

polyethylene (LD/HD-PE), polyvinyl chloride (PVC), polypropylene (PP), and polystyrene (PS). The

monomers of these polymers are produced from hydrocarbons which are often derived from

petrochemicals and natural gas. In fact, 4% of global oil production was used in the feedstock of plastic

production as of 2010 [4].

Thermoplastics are typically lightweight, chemically inert, flexible, strong, and moldable. These

characteristics makes them easy to produce and handle which has revolutionized the manufacturing and

especially the packaging industry in the past century—34% of plastics produced are distributed to the

packaging industry [1]. The benefits of using synthetic plastics for packaging is in that energy

consumption and costs associated with logistics can be reduced as the total mass of packaged product is

decreased. The moldable characteristic of thermoplastics allows the packaging into any shape. However,

synthetic plastics are usually not biodegradable which poses an environmental risk for plastics in landfills

and especially for plastic pollution in the oceans. A recent report from the EPA reports that plastics

comprised 12.9% of municipal solid waste in 2014 which amounts to 33 million tons of plastics. Only

9.5% of total plastic waste was recycled, 15.0% was combusted and 75.5% was put into landfills [3].

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4.2 Plastic Recycling

4.2.1 Conventional Method of Plastic Recycling:

Recycling is a way to prolong the lifetime of plastics. The conventional way of recycling post-consumer

plastics is known as mechanical recycling. Mechanical recycling first involves sorting plastic according

to each resin type. Several measures exist to make recycling feasible. A common feature found in plastic

containers is the ASTM International Resin Identification Coding System (RIC). RIC indicates the type

of plastic resin and also assigns a number to the resin; this makes sorting plastic easier during the initial

stages of recycling. Several sorting techniques exist which make use of the density differences; these are

often easy and cheap to perform. However, they do not yield high selectivity in separation. Near infrared

spectroscopy can be performed to separate different resins with good selectivity in separation although

not suitable for dark colored plastics [http://waset.org/publications/11237/identification-and-

classification-of-plastic-resins-using-near-infrared-reflectance-spectroscopy]. After sorting, the plastic is

granulated, washed, and dried. Oftentimes a flotation test can be incorporated after the washing phase to

increase separation selectivity. The resulting pellets are used for producing plastic goods.

4.2.2 Limitations to Plastics Recycling:

The most commonly recycled plastic products are probably soda and water bottles. In theory, all

thermoplastics can be recycled however, in reality this is difficult. Economically, the low density of

plastics makes plastic collection costly because the mass of plastic transported is small considering the

volume transported. Even though plastic may consist of the same resin, the composition is not the same

because of the different additives used. Recycling different plastics together often yield lower quality

plastics when molded in the same mixture thus decreasing the value of the recycled plastic both in

applicability and economics. In some cases, the cost of recycling plastic is greater than the cost of

producing virgin plastic which is another factor of the low recycle rate of plastic.

4.3 Properties of Conventional Diesel Fuel

4.3.1 Introduction:

Conventional diesel fuel is available to the public in two main variants: number 1 diesel and number 2

diesel. Number 2 diesel is fuel intended for on road use and is the most widely consumed diesel fuel with

the highest number of people consuming this number 2 diesel. Anyone who drives a diesel truck or a TDI

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diesel such as a Volkswagen or Mercedes-Benz, purchases number 2 diesel fuel from the pump station

when they fill up their tank. Number 1 diesel fuel on the other hand is intended for off road use only and

is dyed a strong red color. This diesel fuel is not commonly sold at conventional pumping stations unless

the station is located near or in a farming town as this is the main diesel fuel used in tractors and farm

equipment.

4.3.2 Number 2 Diesel Fuel:

Number 2 diesel fuel has a higher heating value when compared to number 1 diesel fuel. Number 2 diesel

fuel has about 140,000 BTU/Gal for a heating value [26]. Because it has a higher heating value that number

1 diesel fuel, a vehicle that is running on number 2 diesel fuel can expect to produce more power than that

of the same vehicle running on number 1 diesel fuel. Similarly, this same vehicle would be able to travel

the same distance while using less fuel than if it were to be running on number 1 diesel fuel. Starting in

2006 the EPA issued a regulation on the sulfur content in diesel fuel. Prior to 2006, number 2 diesel fuel

contained and average of 2,000 ppm sulfur [26]. Diesel fuel produced after the EPA’s 2006 mandate must

contain less than 15ppm sulfur. This low sulfur diesel fuel is known as ultra-low sulfur diesel or ULSD.

Ultra-low sulfur diesel fuel has been the standard highway used diesel fuel since 2006 in every state except

for Alaska which transitioned to using ultra-low sulfur diesel fuel in 2010. ULSD fuel is now the standard

diesel fuel for diesel trucks and TDI cars.

4.3.3 Number 1 Diesel Fuel:

Number 1 diesel fuel has a lower heating value when compared to number 2 diesel fuel. Number 1 diesel

fuel has a heating value of about 125,000 BTU/Gal. Number 1 diesel fuel is very similar to kerosene and

is named as the number 1 fuel oil as it is the first draw of the middle distillate during the refining process.

As of 2016, number 1 diesel fuel still contains a substantial amount of sulfur compared to its on-road

counterpart at an average of more than 500ppm sulfur [26]. The advantage using high sulfur diesel fuel is

the lubricity increases with added sulfur concentration in the fuel. High sulfur fuel today contains

substantially less sulfur than it did even 15 years ago yet still contains about 30 times more sulfur than is

found in ULSD. Most diesel trucks and farm equipment are older than the 2006 EPA sulfur regulation and

therefore were built to operate on the high sulfur variety of fuel. The lubricative properties of the sulfur in

number 1 diesel fuel help these trucks and farm equipment run properly. For this reason, many diesel

owners are forced to put fuel additives into their vehicles to increase the lubricity of the fuels so their

engines run smoothly.

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4.3.4 Properties of Diesel Fuel:

Pure conventional number 2 diesel gels at around 5 degrees Fahrenheit below zero. Number 1 diesel fuel

does not gel until about 60 degrees Fahrenheit below zero. Gelling of a fuel is a structural transformation

similar to water freezing into ice. When Diesel fuel gels, it turns into a fluid with a consistency similar to

Jell-O. Gelling of diesel fuel prevents the fuel pump from effectively moving the fuel to the engine and the

engine cannot run. For this reason, vehicles that operate on diesel fuel that are subject to cold climate

conditions must be careful with the fuel type they are choosing. Winter blends of diesel fuel use

approximately a 50/50 mixture of un-dyed number 1 diesel and number 2 diesel fuels. This mixture

substantially lowers the gel transition temperature over conventional number 2 diesel to allow use in colder

climates without the worry of the fuel gelling up.

The measure of the overall performance of gasoline is the octane number. The higher the octane rating of

the fuel the slower it will burn and the higher its overall effectiveness in ability to tune the ignition to the

proper timing on the engine. Diesel fuel has a similar measure for effectiveness of a particular blend of

fuel to ignite. Cetane number or the cetane rating is the measure of the combustion speed and required

compression for a particular blend of diesel fuel. Cetane number is effectively the inverse of the Octane

number. The higher the cetane rating the quicker the fuel will ignite. A high cetane rating is more desirable

than a low rating because diesel engines run on compression ignition rather than spark ignition like a

gasoline engine does. Cetane numbers range from 0 to 100 with typical diesel engines operating on fuels

with a cetane number of between 45 and 55. Low speed diesel engines such as towing trucks or farm

equipment can better handle the lower cetane number as a lower number of revolutions per minute allows

more time for the fuel to completely burn. The opposite is true for high RPM diesel engines like a typical

TDI engine as a higher cetane number allows less time for complete ignition to cycle. Some common

additives to raise the cetane number of a fuel, to compensate for the loss of lubricity that the sulfur content

used to provide, and to reduce the gel transition temperature are 2-ethylhexyl nitrate and di-tert-butly

peroxide [27].

Typical carbon numbers for diesel fuels produced from refining crude oil range from 9 to 23 carbon atoms

in length. With molecules with carbon number of 14 to 18 having at or above 10 mass percent each in the

final composition of diesel fuel [26]. This data is for number 2 diesel fuel, however, number 1 diesel fuel

is similar. The data follows a bell curve with the peak being at a carbon number of 16 and decreasing in a

fairly uniform manner at any number of carbons above or below this value. About 1 percent by mass has

9 or fewer carbons or 23 or greater carbons per molecule. These extremes amount to about 2 percent by

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mass of the total distribution found in number 2 diesel fuel. A distribution histogram can be seen in

appendix.

4.3.5 Diesel Derived from the Pyrolysis of Plastic Polymers:

As mentioned above the thermal process that breaks down polymer chains into smaller sizes is called

pyrolysis. Catalytic pyrolysis of waste plastics yields similar carbon chain lengths as that of conventional

number 2 diesel with a peak in concentration found at C16. In a US patent whose inventor is Gary Baker,

a mixture of polyethylene (PE), polypropylene (PP) and polystyrene (PS) was used as the waste plastic

feed. His mixture of 55% PE, 28% PP and 17% PS by mass yielded the desired carbon chain frequency

peak of 16 carbons [25]. Baker’s process yielded an upper limit to of frequencies similar to that of

conventional diesel with C23 and above at essentially zero. The low molecular weight carbon chains held

more of a substantial weight percentage with a higher number of C5 and C6 as well as C13. Apart from

the higher than normal levels of some of the lighter molecules begin present in the fuel it is very similar to

conventional diesel fuel after it gets condensed back into a liquid. This crude product could be refined

further into pure diesel fuel with the exact proportions of each carbon chain number. A distribution

histogram can be seen in appendix.

Green plastic pyrolysis has been used by several companies whose main goal has been to recycle waste

plastic into diesel fuel. The properties of the resulting diesel fuel of one of these groups can be found in

the appendix. The paper in question uses a Y-Zeolite catalyst and utilized feed of HDPE plastics. Both

Diesel number 1 and diesel number 2 were obtained from this experiment. The weights of these fuels

were the standard diesel weights and it was noted that the Y-Zeolite catalyst was a huge benefit to the

properties being such [28]. The Y-Zeolite catalyst significantly lowered the cloud point or the gel

transition temperature to below the detection limit of their equipment which was able to handle down to

50°C below zero. The flash point was at 77 and 74 for two of their runs which was higher than the

required 52°C in standard diesel fuel.

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5.0 Design Variables

There are two types of pyrolysis used to break down plastics into smaller compounds: catalytic and thermal

pyrolysis. After extensive research, catalytic pyrolysis has proven to be a much more effective method of

producing an oil with a composition in the desired range for diesel fuel production. The variety of catalyst

used will be a key design variable in the next phases of this design. The choice of catalyst will directly

affect the limits on the composition of the oil obtained from the feed plastics. As the team moves forward

into the next phase of this project, catalyst optimization will be a key variable

In addition to the reaction process that will be used, the reactor itself must be of a suitable design for

handling a feed of waste plastic. Current plastic recycling methods rely on large shredders to grind the

incoming supply of waste plastic into a homogeneous blend of plastic flakes that can then be re-extruded.

A similar grinder can be used to prepare the waste plastic before entering the reactor. Most research on

waste plastic pyrolysis is carried out on a small scale in stirred batch reactors where the shredded or

pelletized plastic is loaded into the reactor beforehand. However, some small companies have already

implemented a continuous flow process that uses a large baffled rotating drum as the reactor. Alternatively,

a spouted bed reactor has been proposed as a possible method for agitating the mixture of shredded waste

plastic and catalyst with compressed inert gas. Further research is required before continuing with the

design of the reactor.

6.0 Design Norms

As inhabitants of the Earth and stewards of creation as Christians, it is important to maintain and improve

environment for all creatures in the world. We believe that our project will achieve the design norm as

stewards of creation as our process will decrease space occupied by landfills. Stewardship goes beyond

the notion of simply taking care of things. We are called by God in the second chapter of the Bible to

have dominion over the earth and to take care of it. God has given us the responsibility to steward the

resources we have authority over. As Chemical Engineers we deal with a large amount of materials and

we strongly believe it of importance to use the materials we have control over in the most efficient way

possible. A secondary added benefit of this is there will likely be a monetary advantage to the proper use

of materials and resources.

Transparency is a design norm that should be addressed as some people might think that converting

plastic to fuel does not necessarily help conserve the environment. We should address possible

environmental impacts of pyrolysis and plant failure (e.g. reactor failure, leakage of impure stack gas) but

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also improvements from pyrolysis (e.g. less plastic waste circulating in the environment). It is imperative

that those who would potentially have a problem with our process and that think the plant offers a hugely

negative impact on the environment, understand the process enough to make a proper judgement call as to

its actual impact. It is never possible to make someone learn some aspect of a project, plant, process, or

field of study if they are not willing. It is for this reason we will strive to be transparent in our design.

Transparency indicates an innate desire to be truthful as to what we are doing and our intentions behind

our methods. We will aim to give everyone a clear picture of how this process takes waste plastic from

being put into landfills or into the ocean and heats it up really hot and ‘melts’ it into something useful:

Diesel fuel.

7. Conclusion

In the Cultural Mandate, Genesis 1:28, God commands us to "subdue the earth". Nancy Pearcey, in her

book Total Truth, says "this is what we might call the first job description...this means harness the natural

world: plant crops, build bridges, design computers, and compose music". As a team, we seek to fulfill the

cultural mandate by designing a plant to convert waste plastic into diesel fuel. From the research

summarized above, we believe that this project is feasible. More research will be carried out, particularly

with regards to the reactor type, as the team moves forward into the next phase of design.

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Citations

[1] Environmental Protection Agency, “Advancing Sustainable Material Management: 2014 Factsheet,”

November, 2016.

[2] U.S. Energy Information Administration, "Fuel oil and kerosene sales 2015," pg 7, December 2016

[3] U.S. Energy Information Administration, "Annual energy outlook 2016," MT-28, August 2016

[4] U.S. Department of Energy, "Production of gasoline and diesel from biomass via fast pyrolysis,

hydrotreating, and hydrocracking; a design case," February 2009

[5] C, White, D. Gray, "Production of zero sulfur diesel from domestic coal," DOE/NETL-2012/1542,

December 2011

[6] A. Milbrandt, C. Kinchin, R. McCormick, "Feasability of producing and using biomass-based diesel

and jet fuel in the united states," NREL/TP-6A20-58015, December 2013

[7] S.L. Wong, N. Ngadi, T.A.T. Abdullah, I.M. Inuwa, "Current state and future prospects of plastic

waste as source of fuel: a review," Renewable and Sustainable Energy Reviews, vol. 50, pp. 1167-1180,

2015.

[8] Gershman, Brickner & Bratton, Inc., “Gasification of non-recycled plastics from municipal solid

waste in the united states,” august 2013

[9] R. Miandad, M.A. Barakat, A. S. Aburiaziaza, M. Rehan, “Catalytic pyrolysis of plastic waste: a

review”, Process Safety and Environmental Protection, vol. 102, pp. 822-838, 2016

[10] ASTM E 176, “Standard terminology of tire standards,” Annual Book of ASTM Standards, vol. 4.07,

American Society for Testing and Materials, Conshohocken, PA

[11] C.L. Beyler, M.M. Hirschler, “Thermal decomposition of polymers,” The Society of Fire Protection

Engineers Handbook 3rd Ed., New York, Springer 2016

[12] J.A. Onwudili, N. Insura, P. Williams, “Composition of products from the pyrolysis of polyethylene

and polystyrene in a closed batch reactor: effects of temperature and residence time,” Journal of

Analytical and Applied Pyrolysis, vol. 86, pp. 293-303, 2009

[13] R. van Grieken, D.P. Serrano, J. Aguado, R. Garcia, C. Rojo. “Thermal and Catalytic Cracking of

Polyethylene Under Mild Conditions,” Journal of Analytical and Applied Pyrolysis, vol. 58-59, pp. 127-

142, 2001

[14] A. Marcilla, M.I. Beltran, R. Navarro, “Evolution of products during the degradation of polyethylene

in a batch reactor,” Journal of Analytical and Applied Pyrolysis, vol. 86, pp 14-21, 2009

[15] R.W.J. Westerhout, J. Waanders, J.A.M. Kuipers, W.P.M. van Swaaij, “Kinetics of the low-

temperature pyrolysis of polyethene, polypropene, and polystyrene modeling, experimental determination,

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and comparison with literature models and data,” Industrial Engineering Chemistry Research, vol. 36, pp

1955-1964, 1997

[16] R. Sadeghbeigi, Fluid Catalytic Cracking Handbook, Houston: Gulf Publishing, 2000

[17] J.S. Magee, M.M Mitchel Jr., Fluid Catalytic Cracking: Science and Technology, Amsterdam: Elsevier

Publishing, 1993

[18] T.F Degnan Jr., “Applications of zeolites in petroleum refining,” Topics in Catalysis, vol. 13, pp. 394-

356, 2000

[19] M.S. Abbas-adabi, M. Nekoomanesh, H. Yeganeh, A. McDonald, “Evaluation of pyrolysis process

parameters on polypropylene degradation products,” Journal of Analytical and Applied Pyrolysis, vol. 109,

pp. 272-277, 2014

[20] D.S. Achilias, C. Roupakias, P. Megalokonomos, A.A. Lappas, E.V. Antonakou, “Chemical recycling

of plastic wastes made from polyethylene (LDPE and HDPE) and polypropylene (PP),” Journal of

Hazardous Materials, vol. 149, pp. 536-542, 2007

[21] L. Kyong-Hwan, N. Noh, D. Shin, Y. Seo, “Comparison of plastic types for catalytic degradation of

waste plastics into liquid product with spent fcc catalyst,” Polymer Degradation and Stability, vol. 78, iss.

3, pp. 539-544, 2002

[22] Y. Sakata, M.A. Uddin, K. Koizumi, K. Murata, “Thermal degradation of polyethylene mixed with

poly(vinyl chloride) and poly(ethyleneterephthalate),” Polymer Degradation and Stability, vol. 53, iss. 1,

pp. 111-117, 1996.

[23] G. Lou, T. Suto, S Yasu, K. Kato, “Catalytic degradation of high density polyethylene and

polypropylene into liquid fuel in a powder-particle fluidized bed,” Polymer Degradation and Stability, vol.

70, pp. 97-102, 2000

[24] M. Heydariaraghi, S. Ghorbanian, A. Hallajisani, A. Salehhpour, “Fuel properties of the oils produced

from the pyrolysis of commonly used polymers: effect of fractionating column,” Journal of Analytical and

applied Pyrolysis, vol. 121, pp. 307-317, 2016.

[25] G. Baker, "Process and Plant for Conversion of Waste Material to Liquid Fuel" U.S. Patent

9,096.801, issued August 04, 2016.

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[26] Chevron. (2007). Diesel Fuel Tech Review. Huston, TX: Chevron Oil. [12]

[27] Ketal, D. (2005). PHLOX - Enhancing Efficiency with Fuel Additives. In Dorf Ket.

[28] Kunwar, Bidhya et al. "Catalytic and thermal depolymerization of low value post-consumer high

density polyethylene plastic." Energy, vol. 111, 2016, pp. 884-92

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Figure 1: Thermal decomposition of polymers happens via 4 primary mechanisms. The yield of oil, gas,

or char in polymer pyrolysis depends on the distribution of these mechanisms. (Courtesy of ASTM [10])

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Figure 2: The thermal decomposition of polymers proceeds through three primary mechanisms, each

requiring the formation of a free radical. a) intramolecular H transfer, b) intermolecular H transfer, c) end

chain de-polymerization, also known as “unzipping”. (Courtesy of ASTM [10]).

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Figure 3: Temperature dependence on the formation of gas (a), oil (b), and char (c) products resulting

from the thermal and catalytic pyrolysis of LDPE. (Courtesy of J. Anal, Appl, Pyrolysis [13])

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Figure 3: Normal distribution of carbon number and their corresponding mass percent in standard number

2 diesel fuel obtained from refinement of crude oil. [26]

Figure 4: Distribution by mass percent of various carbon chain number resulting from pyrolysis of plastic

in diesel fuel. Courtesy of Baker [25].

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Table 1: Monomer yield from the decomposition of various polymer of general form [CWX-CYZ]n.

(Courtesy of ASTM [10])

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Table 2: Composition of oil resulting from thermal pyrolysis of polystyrene at various temperatures

(courtesy of J. Anal. Appl. Pyrolysis [12])

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Table 3: Major components of oil resulting from thermal pyrolysis of polystyrene in relation to residence

time in a batch reactor at 400°C. (courtesy of J. Anal. Appl. Pyrolysis [12])

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Table 4: Composition of oil resulting from thermal pyrolysis of LDPE at various temperatures (courtesy

of J. Anal. Appl. Pyrolysis [12])

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Table 5: Major components of oil resulting from thermal pyrolysis of LDPE in relation to residence time

in a batch reactor at 450°C. (courtesy of J. Anal. Appl. Pyrolysis [12])

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Table 6: Product yield from the catalytic pyrolysis of LDPE, HDPE, and PP. (Courtesy of J. Haz Mat.,

[20])

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Table 7: Composition of the gaseous product derived from catalytic pyrolysis of virgin LDPE, HDPE.

(courtesy of J. Haz. Mat. [20])

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Table 8: Compounds identified in the liquid product of catalytic pyrolysis of virgin LDPE, HDPE, and PP.

(courtesy of J. Haz. Mat. [20])

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Table 9: Fuel properties of motor gasoline and diesel obtained from green plastics pyrolysis. (Courtesy of

Bidhya [28])

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Table 10: Composition and Properties of HDPE distillates. (Courtesy of Bidhya [28])