Catalytic Thermal Cracking of Postconsumer Waste Plastics to Fuels. 2

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Catalytic Thermal Cracking of Postconsumer Waste Plastics to Fuels. 2. Pilot Scale Thermochemical Conversion Bidhya Kunwar, Sriraam R Chandrasekaran, Bryan R. Moser, Jennifer L Deluhery, Pyoungchung Kim, Nandakishore Rajagopalan, and Brajendra K. Sharma Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.6b02996 • Publication Date (Web): 15 Feb 2017 Downloaded from http://pubs.acs.org on February 19, 2017

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Catalytic Thermal Cracking of Postconsumer Waste Plastics to Fuels. 2. Pilot Scale Thermochemical Conversion Bidhya Kunwar1, Sriraam R. Chandrasekaran1, Bryan R. Moser2, Jennifer Deluhery1, Pyoungchung Kim3, Nandakishore Rajagopalan1, and Brajendra K. Sharma1* 1

Illinois Sustainable Technology Center, Prairie Research Institute, University of Illinois, Urbana

Champaign, Illinois-61820, USA 2

United States Department of Agriculture, Agricultural Research Service, National Center for

Agricultural Utilization Research, Bio-Oils Research Unit, Peoria, Illinois 61604, USA 3

Center for Renewable Carbon, University of Tennessee, 2506 Jacob Dr. Knoxville, TN 37996,

USA

ABSTRACT: Synthetic gasoline and diesel fuels were prepared via catalytic and non-catalytic pyrolysis of waste polyethylene and polypropylene plastics followed by distillation of plastic crude oils. Reaction conditions optimized using a 2 L batch reactor were applied to pilot-scale production of plastic crude oil from polypropylene. The optimum conditions on pilot-scale system were a reaction temperature of 500°C and a residence time of 4.7 min. Plastic crude oil yields at pilot-scale were comparable to the batch-scale (70-80%). Plastic crude oils obtained from pyrolysis were distilled into boiling point range of motor gasoline, diesel #1, gas oil, and vacuum gas oil range fractions. The elemental composition of the crude oil and its distillates were similar to the starting plastic material. Fuel properties were studied for both neat and in blends (5% and 20%) with ultra-low sulfur diesel fuel (ULSD). Excellent low temperature 1 ACS Paragon Plus Environment

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properties were obtained for some of the samples, as indicated by a pour point of < -74°C and cold filter plugging point of (CFPP) < -50°C. Oxidative stabilities and kinematic viscosities of plastic diesel-range samples were found to be within the limits prescribed in American (ASTM D975) and European (EN 590) petroleum standards, where applicable. In addition, the plastic diesel-range samples yielded greater energy content than ULSD. Three plastic diesel-range samples were selected for further evaluation as blend components in ULSD, as these were determined to have the best combination of fuel properties relative to the other diesel range samples. The 5 & 20% blends exhibited superior low temperature performance relative to ULSD. In addition, oxidative stability was not negatively affected by blend ratio. All blends provided oxidative stabilities and kinematic viscosities within the ranges specified in the petrodiesel standards. Density decreased slightly and energy content increased with increasing concentration of plastic diesel-range sample in ULSD. In summary, our results demonstrated that plastic dieselrange sample prepared from pilot-scale pyrolysis of waste plastics followed by distillation can be used as drop-in or as blend components with ULSD without negatively affecting fuel properties of ULSD. Keywords: Pyrolysis, waste plastics, pilot-scale, diesel, distillation

*Corresponding authors: [email protected] (Brajendra K. Sharma) and [email protected] (Bidhya Kunwar)

2 ACS Paragon Plus Environment

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1.

INTRODUCTION In our previous pyrolysis study, all process variables such as temperature, time, nitrogen

flow rate, and particle size that affected pyrolysis were screened in a rapid fashion using a statistical design of experiments approach and optimized using thermogravimetric analysis (TGA).1,2 The results predicted by the models developed using TGA were validated using a bench scale reactor for polypropylene1 and polyethylene2, and the obtained crude oils and their corresponding distillates were characterized for chemical and fuel properties. The present study demonstrates application of these results to the pilot-scale pyrolysis of polypropylene corrugated black plastic (used for advertisement) while identifying the challenges during the scale up processes. Operational difficulties and modifications need to be made when moving from batch scale to large scale production. Pilot-scale studies expose the obstacles that will be encountered as production rates increase and is an important step to bridge gap between batch-scale and continuous large-scale pyrolysis.3 The key point for industrial scale operation is to increase the capacity of the pyrolysis unit to increase the commercial viability of the process.4 Miskolczi et al.4 investigated the catalytic degradation of polyethylene (PE) and polypropylene (PP) at 520°C in a pilot scale reactor. Their product differed between batch- and pilot-scale runs yield and composition. Milne et al.5 found that these differences are due to the residence time of the plastic in the reactor. The pilot-scale study by Li et al.3 showed an oil yield of 42.9-45 wt% for scrap tire pyrolysis at 450 – 650°C on a rotary kiln reactor; whereas, the batch scale study by Berrueco et al.6 showed the oil yield to be 30-43 wt% for tire pyrolysis in a static-bed batch reactor at 400 – 700°C. Commercial pilot-scale reactors used for plastics pyrolysis are fluidized beds, vacuum moving beds, two-stage moving beds, ablative beds, and rotary kilns.3 Yield and product


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composition depends on plastics type, reactor type, operating temperature, heat distribution and residence time.7 Short residence times and high operating temperature in pilot scale pyrolysis favors the conversion of plastic into 90 wt.% gas with total olefin yields as high as 75 wt.%.5 Crude oil yield from tire pyrolysis in a vacuum moving bed reactor was reported between 43 – 56% at 485 – 550°C.8 Crude oil yield from mixed plastics pyrolysis in fluidized beds was between 32 and 50% at 680 – 790°C.9 The oil yield reached a maximum value of 45.1 wt% from scrap tire pyrolysis in a rotary kiln reactor at 500°C.3 Catalytic pyrolysis is the most common technique as it lowers the energy required to break large polymers into small hydrocarbons in batch-scale reactions.1,7 ZSM-5 catalyst (5 wt.%) use for pyrolysis of plastic waste resulted in gasoline and light oil yields of 20-48% and 17-36% respectively depending on process parameters.4 However, the use of catalysts is problematic in pilot-scale pyrolysis because of presence of some elements (N, S, P, and Ca) in mixed plastic waste from agricultural and packaging sectors, which may affect catalyst performance. Catalyst might accumulate in the residue or coke and removal of deactivated catalyst from the product is another issue.10 The objectives of this study were to (1) conduct a comparative pyrolysis study of PP corrugated black plastic in batch and pilot-scale reactors using a previously optimized method;1,2 (2) distill plastic crude oil (PCO) into different boiling range fractions corresponding to diesel and gasoline and characterize the fractions; and (3) study the fuel properties of the resulting synthetic diesel fractions along with their blends with ultra-low sulfur (< 15 ppm S) diesel (ULSD) fuel. The study focused on maximizing the efficiency of plastic crude oil production through pilot-scale pyrolysis by studying the effects of temperature and time on the yield and quality of fuel fractions and comparing these with fuels from batch pyrolysis runs.


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The study also compared the fuel properties of synthetic diesel fuel made using pilot scale and batch pyrolysis of various waste plastics. The waste plastics included corrugated black plastic (PP), medicine bottles (PP) and high density PE (HDPE) green plastic storage boxes. Synthetic diesel blends were prepared by mixing diesel range fraction from PP and PE to simulate mixed plastic waste, and their fuel properties were determined. Lastly, fuel properties of blends (5 & 20%) of synthetic diesel with ULSD were also prepared and the resultant fuel properties measured.

2.

EXPERIMENTAL

2.1

Materials. PP corrugated black plastic (BP) and medicine bottles (MB) and HDPE green

plastic (GP) were shredded into particles of ~5 mm diameter using an AEC Nelmor shredder (Blade machinery Co., Inc, Elk Grove Village, IL) before pyrolysis. Summer-grade ultra-low sulfur (< 15 ppm S) diesel (ULSD) fuel was provided by a commercial petrochemical company that wishes to remain anonymous. With the exception of conductivity and corrosion inhibitor additives, the ULSD contained no performance-enhancing additives. All other chemicals were obtained from Sigma-Aldrich Corp (St. Louis, MO). All materials were used as received. 2.2

Thermochemical conversion.

Batch scale pyrolysis: Pyrolysis of black plastic was conducted for two hours in a 2 L batchscale reactor at 450 and 500°C as described in earlier studies.1,2,11 The plastic crude oils produced from batch-scale pyrolysis at 450 and 500°C are referred to as BP450 and BP500 respectively. The numbers in the sample ID represent the temperature at which pyrolysis was conducted. MB450 is plastic crude oil from pyrolysis of PP medicine bottles (MB) at 450°C as described in a paper by Chandrasekaran et al.1 while GP/MgCO3 is plastic crude oil from catalytic pyrolysis


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of HDPE green plastic at 450°C in presence of MgCO3 as described by Kunwar et al.2 The details of these samples along with pyrolysis conditions are listed in Table 1. Pilot-scale pyrolysis of polypropylene plastic: Pilot scale validation of plastic pyrolysis was conducted using a semi-pilot-scale continuous auger pyrolysis system (CAPS) located at the Center for Renewable Carbon in the University of Tennessee (Knoxville, TN). The CAPS consisted of a feeding system, rectangular auger reactor, three condensers in series for oils, and a collector for solids. A detailed description of the auger pyrolysis system is provided elsewhere.12,13 The feeding system included a feedstock hopper that can handle feeding rates of 3 - 20 kg/h. The auger pyrolysis reactor has an electrical resistance furnace system (10W × 10H × 250L cm) with controllable furnace temperature throughout the 2 x 2 furnace zone (zone 1 at start and zone 2) with operating temperatures ranging from 100 to 1100 °C, and an internal dual augers controlling the speed of sample transport through the reactor and an operation temperature ranging from 100 to 1100°C. The auger speed (rotations per minute, rpm) controls the residence time of the feedstock ranging from 15 seconds to 7 minutes. The furnace is also equipped with a fine particle precipitator (20 cm diameter ×100 cm length) located between the reactor and the first condenser. The pyrolytic vapor was collected in three different condensers (20 cm in diameter and 100 cm long) which were cooled to 20°C using a water cooling circulation system (7 L/min, Chiller, Polyscience Inc.). The solid residue was collected into a drum using an ash auger at the exit of the furnace. The reactor maintained a nitrogen environment for pyrolysis with a continuous flow of nitrogen gas at 20 L/min. Pilot Scale Optimization: Polypropylene black plastic, pre-shredded into particles of approx. 5 mm diameter, was added in the feed hopper and then transferred by a feed auger into the reactor heated to either of these three temperatures (500, 525, or 550°C). Oven dual augers, maintained


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at approximately 3 rpm, allowed for a sample residence time of approx. 4.7 min. Based on batch pyrolysis runs, pyrolysis temp of 450°C was tested and found that this temperature was low for pilot scale system to completely depolymerize the plastics. This run resulted in melted plastic blocking rotation of the dual augers in the reactor. Thus, optimization was conducted at temperatures of 500, 525, and 550°C for 4.7 min sample residence time. The optimized conditions of 500°C and sample residence of approx. 4.7 min were then used for converting black plastic to 43kg of crude oils. The plastic crude oil produced from pilot-scale pyrolysis at 500°C is referred to as BP500 PS, where the numbers represent the temperature at which pyrolysis was conducted and PS refers to pilot scale. This PCO sample (BP500 PS) was then analyzed and compared with PCOs obtained from batch scale pyrolysis of black plastic (BP450 and BP500) for their chemical and fuel properties. Distillation: Plastic crude oils obtained from batch and pilot scale pyrolysis were distilled in an automated 36-100 spinning band distillation system (BR instrument, Easton, MD) as described earlier.2 Plastic crude oils were separated into six fractions : 62), thereby suggesting that this sample contained the highest concentrations of linear and longer-chain hydrocarbons. Furthermore, without exception, samples that yielded pour point < -74°C and CFPP < -50°C also provided DCNs < 40. High DCN of synthetic diesel from GP w/MgCO3 (PE) was one reason to blend it with other polypropylene derived synthetic diesel (MB450 and BP450) to study how this blending will increase calculated DCN and affect low temperature flow properties and oxidation stability. It was found that calculated DCN can be improved to meet ASTM D975 specifications. Cold flow properties were also found to be better than ULSD. Oxidation stability of blends was better than synthetic diesel of GP w/MgCO3, but still did not meet the stricter EN specification. Synthetic diesel blend of MB450 and GP w/MgCO3 didn’t meet viscosity specifications, but 1:1 blend of BP450 and GP w/MgCO3 did meet both ASTM and EN specifications for viscosity. Therefore, two more blend ratios (1:3 and 3:1) of BP450 and GP w/MgCO3 were prepared.


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Synthetic diesel blend (3:1) of BP450 and GP w/MgCO3 showed excellent low temperature flow properties, met viscosity specifications of ASTM and EN, good oxidation stability with IP of 8.6 h, and high calculated DCN value of 47.1. ASTM D975 does not contain a density specification, but EN 590 prescribes a range of 820 – 845 kg/m3 at 15°C. None of the synthetic fuel samples provided densities within the range specified in EN 590. In contrast, ULSD conformed to EN 590 with a density of 849 kg/m3. The lower densities relative to the ULSD of the samples may be due to the presence of aromatics in the ULSD. Aromatics exhibit higher densities than linear, branched and cyclic hydrocarbons that are more likely to comprise the synthetic samples.26 As mentioned previously, aromatics were not detected in the synthetic samples. Also measured was SG, which is not specified in the petrodiesel standards. As was the case with density, the SGs of the samples were lower than that of ULSD (0.841). Even though surface tension influences fuel atomization, it is not specified in either ASTM D975 or EN 590.27 The surface tensions of the synthetic samples (< 23.9 mN/m) at 40°C were below the value obtained for ULSD (25.1 mN/m). This observation is in agreement with the Macleod-Sugden parachor, which established a relationship between density and surface tension of a liquid in which lower densities lead to lower surface tensions and vice versa.27 The HHVs of the synthetic fuel samples (> 46.11 MJ/kg) were higher than ULSD (45.15 MJ/kg) indicating potential for use as liquid fuels. The higher HHVs of the samples relative to ULSD was attributed to the presence of aromatics in ULSD, as aromatics contain less energy than aliphatic constituents likely to comprise the synthetic samples. Therefore, the lack of aromatics in the synthetic samples versus ULSD causing lower density and SG may also be partially responsible for higher energy content. In addition, the synthetic sample yielding the highest energy content (GP w/ MgCO3; 46.46 MJ/kg) also provided the highest DCN, but poor


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cold flow properties amongst plastic derived synthetic diesels, but better than ULSD. Longerchain hydrocarbons not only increase DCN and melting point, but also contain greater energy content due to the presence of a larger number of energetic carbon-hydrogen bonds. Energy content is not specified in the petrodiesel standards. 3.6

Blends with ULSD. Three diesel like fractions with best fuel properties were selected as

blend component in ULSD at 5 and 20% level. Samples selected for blending were MB450, GP w/MgCO3 and a 1:1 mixture of MB450 with GP w/MgCO3, as these were determined to have the best combination of fuel properties relative to the other samples. Depicted in Table 8 are fuel properties of blends of selected PP, PE and blended PP +PE synthetic diesels with ULSD. Fuel properties determined for the blends were cold flow (CP and pour point), density, oxidative stability (IP), AV, HHV, KV, lubricity, and ST. Other properties such as CFPP, DCN and SG were not measured due to insufficient sample size. As the percentage of synthetic samples increased in blends with ULSD, pour point became progressively lower due to the superior low temperature performance of the samples relative to ULSD. However, CP increased on adding synthetic diesel in ULSD despite the fact that the CPs of the unblended samples were significantly lower than ULSD. A potential explanation for such a phenomenon may be that the samples become less soluble in ULSD at sub-ambient temperatures, thus facilitating crystallization. CFPP was not measured due to insufficient sample volume. Oxidative stability was not negatively affected as the percentage of sample increased in blends with ULSD, as nearly all 5 and 20% blends yielded IPs > 24 h. The lone exception was the 20% blend of GP w/MgCO3 in ULSD, which provided an IP of 21.5 h. This result was not


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surprising, as neat GP w/MgCO3 yielded a low IP (1.3 h). Comparison to the IP specification listed in EN 590, all of the blends were above the minimum limit of 20 h. Lower KVs were noted as the concentration of synthetic samples increased in blends with ULSD. In addition, all blends provided KVs lower than that of unblended ULSD. Comparison of these results to ASTM D975 and EN 590 revealed that all blends were within the limits prescribed in the petrodiesel standards. Progressively shorter wear scars were observed as blend ratio increased due to the enhanced lubricities of the synthetic samples relative to ULSD. With the exception of the 5% GP w/MgCO3 blend, all blends yielded lubricities that were below the maximum limits specified in ASTM D975 and EN 590. It was not surprising that the GP w/MgCO3 blends exhibited the longest wear scars, as unblended GP w/MgCO3 provided the longest wear scar of the synthetic samples blended with ULSD. Density decreased as the percentage of sample increased in blends with ULSD. All blends provided densities that fell within the range specified in EN 590. In addition, all blends did not contain a detectable amount of acids, as determined via AV. Such a result was expected, as the unblended synthetic samples also had low AVs, as discussed in the previous section. Lastly, energy content of the blends increased with increasing concentration of synthetic fuel in ULSD. This was expected, as the synthetic samples provided higher HHVs than ULSD. The highest increases were noted for GP w/MgCO3 blends, which was because GP w/MgCO3 contained the greatest energy content of the synthetic samples studied in this project.

4.

CONCLUSIONS


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Synthetic gasoline and diesel fuels were prepared via pilot and batch scale pyrolysis of waste PE and PP plastics followed by distillation. Reaction conditions were optimized using a bench-scale (2 L) batch reactor and then applied to pilot-scale production of PCO. The optimum pilot-scale conditions were a reaction temperature of 500°C and a residence time of 4.7min. Similar yields of 70 – 80% PCO were noted at batch- and pilot-scale. In general, PCO yield decreased and syn-gas production increased with higher reaction temperatures. Gasoline- and diesel-range fractions were obtained from batch and pilot-scale PCO by distillation. Elemental analyses of intact plastics, PCOs and the distillates were similar and showed a large percentage of carbon (85 – 86%) with the remainder consisting of hydrogen (14%) and a negligible amount of nitrogen with no oxygen, thereby resulting in a calculated higher heating value of approximately 50 MJ/kg. Synthetic diesel from batch-scale PCOs (BP450, BP500) and pilot scale PCO (BP500PS) yielded a pour point of < -74°C and CFPP < -50°C, indicating excellent low temperature performance. The oxidative stabilities of MB450 (20.8 h), BP500 (22.7 h) and BP500PS (> 24 h) were above the minimum limit (110°C) of 20 h prescribed in EN 590. KVs for most of the samples were within the ranges specified by ASTM D975 and EN 590. Energy content was higher than ULSD. MB450, GP w/MgCO3 and 1:1 MB450/ GP w/MgCO3 were selected for further evaluation as blend components in ULSD, as these were determined to have the best combination of fuel properties relative to the other samples. The blends exhibited superior low temperature performance relative to ULSD. In addition, oxidative stability was not negatively affected by blend ratio. All blends provided IPs above 20 h. The KVs of the blends were also within the ranges specified in the petrodiesel standards. Density decreased with increasing concentration of synthetic diesel in ULSD. HHV increased with increasing amount of sample in ULSD. In summary, our results demonstrated that synthetic diesel prepared from


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pyrolysis and distillation of waste plastics can be used neat or as blend components with ULSD without negatively affecting fuel properties of ULSD.

Disclaimer Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture (USDA). The USDA is an equal opportunity provider and employer.

Notes The authors declare no competing financial interest.

ACKNOWLEDGEMENTS The authors thank the Environmental Research and Education Foundation (EREF) and HWRF of ISTC for financial support. Benetria Banks (USDA ARS NCAUR) is acknowledged for technical assistance. The authors also thank the Microanalysis Lab and the Material Research Lab at the University of Illinois at Urbana-Champaign, and the Southwest Research Institute for technical assistance.

SUPPORTING INFORMATION Figure S1 shows FT-IR of motor gasoline and diesel fractions obtained from the pyrolysis of black plastic in comparison to petroleum gasoline and diesel.


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(16) Dawood, A.; Miura, K. Catalytic pyrolysis of γ-irradiated polypropylene (PP) over HYzeolite for enhancing the reactivity and the product selectivity. Polym. Degrad. Stab. 2002, 76 (1), 45–52. (17) Dawood, A.; Miura, K. Pyrolysis kinetics of γ-irradiated polypropylene. Polym. Degrad. Stab. 2001, 73 (2), 347–354. (18) Bagri, R.; Williams, P. T. Catalytic pyrolysis of polyethylene. J. Anal. Appl. Pyrolysis 2002, 63 (1), 29–41. (19) Pinto, F.; Costa, P.; Gulyurtlu, I.; Cabrita, I. Pyrolysis of plastic wastes. 1. Effect of plastic waste composition on product yield. J. Anal. Appl. Pyrolysis 1999, 51 (1–2), 39–55. (20) Pinto, F.; Costa, P.; Gulyurtlu, I.; Cabrita, I. Pyrolysis of plastic wastes: 2. Effect of catalyst on product yield. J. Anal. Appl. Pyrolysis 1999, 51 (1–2), 57–71. (21) Harries, M. E.; Kunwar, B.; Sharma, B. K.; Bruno, T. J. Application of the Advanced Distillation Curve Method to Characterize Two Alternative Transportation Fuels Prepared from the Pyrolysis of Waste Plastic. Energy Fuels 2016, 30 (11), 9671–9678. (22) Knothe, G.; Steidley, K. R. Kinematic viscosity of biodiesel fuel components and related compounds. Influence of compound structure and comparison to petrodiesel fuel components. Fuel 2005, 84 (9), 1059–1065. (23) Knothe, G.; Steidley, K. R. Lubricity of components of biodiesel and petrodiesel. The origin of biodiesel lubricity. Energy Fuels 2005, 19 (3), 1192–1200. (24) American Society for Testing and Materials (ASTM). Standard specification for diesel fuel oils; 2014. (25) Knothe, G.; Matheaus, A. C.; Ryan, T. W. Cetane numbers of branched and straight-chain fatty esters determined in an ignition quality tester. Fuel 2003, 82 (8), 971–975.


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Energy & Fuels

(26) Moser, B. R. Efficacy of specific gravity as a tool for prediction of biodiesel-petroleum diesel blend ratio. Fuel 2012, 99, 254–261. (27) Ejim, C.; Fleck, B.; Amirfazli, A. Analytical study for atomization of biodiesels and their blends in a typical injector: surface tension and viscosity effects. Fuel 2007, 86 (10), 1534–1544.


Energy & Fuels

80 Particle Condenser Condenser 1 Condenser 2 Condenser 3 From Auger Leak

60

% Yield

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 40

40

20

0 500 Degree C

525 Degree C

550 Degree C

Temperature

Figure 1. Plastic crude oil yields from pilot scale optimization runs at various temperatures.


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Energy & Fuels

Figure 2. Fractional yield from pilot scale pyrolysis at temperature of 500 °C.


Energy & Fuels

>350 C 290-350 C 185-290 C 350 C

35-185 C 185-350 C >350 C

35-185 C 185-350 C >350 C

BP450

BP 500

BP 500 PS

Distillation fractions of crude oil (ᵒC) < 185 ᵒC

185-195 ᵒC

195-290 ᵒC

290-350 ᵒC

>350 ᵒC

Figure 4. Boiling point distribution (using simulated distillation) of the fractions (35-185ºC, 185-350 ºC, and 350 ºC +) obtained from distillation of PCO resulting from pilot (PS) and batch scale pyrolysis at 450 and 500 ºC.


Energy & Fuels

0.25 0.25

BP 450 Diesel #2

0.20

BP 450 MG

0.20

0.15 0.15 0.10 0.10 0.05 0.05 0.00 0.00 4000 4000 0.25

3500

3000

2500

2000

1500

1000

BP 500 MG

0.15

0.10

0.10

0.05

0.05

0.00

2500

2000

1500

1000

500

1000

500

1000

500

BP 500 Diesel #2

0.00 3500

3000

2500

2000

1500

1000

500

0.25

4000

3500

3000

2500

2000

1500

0.25

BP 500 PS MG

0.20

BP 500 PS Diesel #2

0.20

0.15

0.15

0.10

0.10

0.05

0.05

0.00 4000

3000

0.20

0.15

4000

3500

500 0.25

0.20

Absorbance

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 32 of 40

0.00 3500

3000

2500

2000

1500

1000

500

4000

3500

3000

2500

2000

1500

Wavenumber

Figure 5. FT-IR showing the presence of alkanes and alkenes in motor gasoline and diesel fractions obtained from the pyrolysis of black plastic.


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Energy & Fuels

Table 1. Plastic crude oils obtained through non-catalytic and catalytic pyrolysis processes Plastic

Plastic type

Pyrolysis temp (ºC)

Process

Catalyst

Black plastic

PP

450

Batch scale

None

BP450

Black plastic

PP

500

Batch scale

None

BP500

Black plastic

PP

500

Pilot scale

None

BP500 PS

Green plastic

HDPE

450

Batch scale

MgCO3

Medicine bottle

PP

450

Batch scale

None


Plastic to catalyst

10:1

Abbreviation

GP/w MgCO3 MB450

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Table 2. Properties of polypropylene (black corrugated plastic) and its plastic crude oil produced at various conditions Plastic (BP) Pyrolysis yield (wt.%) CHN Analysis % HHV (MJ/kg) Molecular weight distribution

Plastic crude oil Residue gas C H N

85.1 14.6 0.3 49.5

Mn Mw PDI

BP450 83.6 3.00 13.4 85.5 14.5 0.00 49.5 351 409 1.30


BP500 86 0.60 13.4 85.6 14.4 0.00 49.5 588 699 1.20

BP500 PS 73.7 0.3 26 85.0 14.6 0.00 49.5 774 912 1.20

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Energy & Fuels

Table 3. Molecular weight distribution of distillate fractions in the range of motor gasoline, diesel #2 and VGO range fractions obtained from pilot and batch scale pyrolysis of PP Black Plastic at 450 and 500°

Fuel fraction (Boiling Point) Motor Gasoline (35-185°C) Diesel #2 (185-350°C) VGO (350°C +)

Sample 1. BP 450 2. BP 500 3. BP 500 PS 4. BP 450 5. BP 500 6. BP 500 PS 7. BP 450 8. BP 500 9. BP 500 PS

Mn

Mw

PDI

59.5 66.3 50.3 180.7 200.7 196.0 680 866 1017

81.0 84.3 73.0 246 270 301 771.7 988.3 1144

1.36 1.27 1.43 1.36 1.35 1.54 1.13 1.14 1.12


Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Table 4. Elemental composition and higher heating value of motor gasoline, diesel #2, and vacuum gas oil range fractions obtained from pyrolysis of batch and pilot scale PCOs

Fuel fraction (Boiling Point) Motor Gasoline (35-185°C) Diesel #2 (185-350 °C) Vacuum gas oil (350 °C +)

Sample

C%

H%

N%

O%

BP 450 BP 500 BP 500 PS BP 450 BP 500 BP 500 PS BP 450 BP 500 BP 500 PS

85.5 85.4 85.6 85.5 85.6 85.5 85.6 85.5 85.7

14.3 14.4 14.2 14.3 14.4 14.3 14.3 14.4 14.1

0.20 0.20 0.20 0.20 0.00 0.20 0.02 0.03 0.00

0 0 0 0 0 0 0 0 0.1


HHV (MJ/kg) 49.2 49.4 49.2 49.3 49.4 49.3 49.3 49.4 49.1

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Energy & Fuels

Table 5. Relative percentages of alkanes and alkenes in motor gasoline and diesel range fractions of pilot and batch scale PCOs from black plastic as determined by 1H-NMR spectroscopya Fuel fraction (Boiling Point) Motor Gasoline (35-185°C)

Sample

Alkanes proton %

Alkenes proton %

1. BP 450

89.7

10.3

2. BP 500

89.6

10.5

89

11.0

4. BP 450

93.4

6.6

5. BP 500

93.5

6.5

6. BP 500 PS

93.8

6.2

3. BP 500 PS Diesel #2 (185-350 °C)

a

Percentages determined using integration values obtained from 1H NMR spectra of signals corresponding to

chemical shifts indicative of the functionalities indicated (Alkenes: 4.5–6.5 ppm; Alkanes: 0.5–2.7 ppm).


Energy & Fuels

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Page 38 of 40

Table 6. Fuel properties of synthetic diesel fuels prepared under various conditions along with a comparison to ULSDa Units CP Pour point CFPP IP, 110 °C AV KV, 40 °C DCN Wear scar, 60 °C SG, 15 °C Density, 15 °C HHV

a

o

C C o C h mg KOH/g mm2/s o

µm kg/m3 MJ/kg

Methods

ULSD

MB450

ASTM D5773 ASTM D5949 ASTM D6371 EN 15751 AOCS Cd3d-63

-18 -20 (1) -16 > 24 N/D

-71 (1) < -74 < -50 20.8 (3.1) 0.38 (0.02) 1.96

ASTM D445 ASTM D6890 ASTM D6079 ASTM D4052 ASTM D6371 ASTM D4809

2.28 (0.01) 47.4 (0.9) 581 (5) 0.841 849 (1) 45.15 (0.19) 25.1 (0.2)

34.8 (0.6) 169 (2) 0.791 790 46.16 (0.26) 22.6 (0.1)

GP w/MgCO3 -23 (1) -27 (1) -27 (1) 1.3 (0.1) N/D 1.73 63.7 (1.3) 433 (22) 0.791 790 46.46 (0.08) 24.0 (0.1)

BP450

BP500

BP500 PS

-25 (1) < -74 < -50 17.1 (1.7) 0.30 (0.03) 2.42 (0.01) 38.2 (0.8) 229 (15) 0.797 797 46.11 (0.11) 23.1 (0.1)

-33 (2) < -74 < -50 22.7 (1.0) 0.37 (0.01) 2.49 (0.01) 38.6 (0.7) 202 (6) 0.798 797 46.20 (0.18) 23.4 (0.1)

-37 (1) 24 N/Db

-16 -33 (1) > 24 N/D

20% GP 5% GP w/MgCO3 w/MgCO3

-15 -29 (1) > 24 N/D

-16 -30 (1) 21.5 (1.5) N/D

5% 1:1 20% 1:1 MB450/ MB450/ GP GP w/MgCO3 w/MgCO3 -15 -29 (1) -26 -31 (1) > 24 > 24 N/D N/D

2.21 2.15 2.19 2.13 2.19 2.10 417 (8) 306 (9) 524 (3) 267 (11) 447 (6) 310 (5) 845 837 845 837 845 837 24.8 (0.1) 24.4 24.8 (0.1) 24.6 (0.1) 24.8 (0.1) 24.6 (0.1) 45.24 45.41 45.42 45.58 45.24 45.19 (0.20) (0.25) (0.28) (0.18) (0.13) (0.14) Values in parentheses represent standard deviations from the reported means (n=3).Where no value is indicated, standard deviation was zero. None detected.


Catalytic Thermal Cracking of Postconsumer Waste Plastics to Fuels. 2

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