Pyrolysis Of Scrap Tires Research Articles

Scrap tyre pyrolysis: Modified chemical percolation devolatilization (M-CPD) to describe the influence of pyrolysis conditions on product yields

This paper attempts to develop a modified chemical percolation devolatilization (M-CPD) model that can include heat transfer, primary pyrolysis and the secondary cracking reactions of volatiles together to describe the pyrolysis of waste scrap tyre chip, as well as to examine the influence of operating conditions on the scrap tyre pyrolysis product yields. Such a study has yet to be conducted in the past, thereby leading to a large knowledge gap failing to understand the pyrolysis of the coarse feedstock appropriately. To validate the developed model, a number of operating parameters including reactor configurations, carrier gas compositions (argon and argon blended with CO2 and/or steam), scrap tyre chip size (0.5–15.0 mm), terminal pyrolysis temperature (400–800 °C) and heating rate (10 °C/min and 110 °C/min) were examined in a lab-scale fixed-bed pyrolyser, with a particular focus on the secondary cracking extents of the liquid tar. Through both experimental investigation and modelling approach, it was found that significant secondary cracking extent occurred upon the increase in the feedstock size, heating rate and residence time. Upon the fast pyrolysis, the average temperature gap between the centres of the coarse particle and reactor wall could reach a maximum of 115 °C for the tyre chips of 6–15 mm. Consequently, its primary volatiles underwent the secondary cracking reaction at an overall extent of 17% at a terminal temperature of 600 °C and a fast heating rate of 110 °C/min. Consequently, the yield of light gases including methane was increased remarkably. The flow rate of inert carrier gas was also influential in the secondary cracking, in which a maximum tar yield (54 wt%) was reached at a carrier gas flow rate of 1.5 L/min. This indicates the occurrence of secondary cracking has been largely minimised. At a pyrolysis temperature of 600 °C, the addition of CO2 in the carrier gas had an insignificant effect on the product yield distribution under the slow heating scheme. In contrast, the addition of steam resulted in a slight increase of carbon monoxide, presumably due to the occurrence of gasification reaction.

Liquefaction of natural rubber to liquid fuels via hydrous pyrolysis

In this study, the natural rubber (NR) was liquefied to produce liquid fuels using hydrous pyrolysis technique. The study was performed in the autoclave batch reactor at different temperatures (300–400 °C), with different water to natural rubber mass ratios (1:1–5:1) and different reaction times (15–75 min). The effect of different parameters then was evaluated on the liquid product in term of quantity and quality. The results showed that the highest liquid yield of 76 wt% was obtained at temperature, H2O/material mass ratio and time of 375 °C, 3:1 and 30 min respectively. Among the parameters, temperature was found to be the most important parameter, showing a notable positive effect on the liquid oil quality and quantity. The characterization results showed that the oil had high energy density, low oxygen and sulfur contents, and non-acidic. The GC–MS analysis showed that the obtained oil was dominated by alkenes, aromatics and alkyls. From all characteristic results it showed that the oil from NR was more suitable to be used as fuel compare to the oil derived from scrap tire, where the study on hydrous pyrolysis of scrap tire was also provided in this manuscript as comparative study. In addition, the production of oil from the hydrous pyrolysis of NR in Malaysia could add to the energy potential about 15 PJ/year or equivalent to 2.5 million barrels of oil per year.

Clean pyrolysis oil from a continuous two-stage pyrolysis of scrap tires using in-situ and ex-situ desulfurization

Abstract Scrap tire pyrolysis was conducted to produce low sulfur oil (below 0.45 wt%), which is strongly demanded for reduction of SOx emissions. In the experiments, a continuous two-stage pyrolyzer consisting of an auger reactor and fluidized bed reactor and various additives (CaO, Fe, FeO, calcined olivine) and fluidizing media (product gas and N2) were tested for the in-situ desulfurization. The auger reactor operated at ∼340 °C yielded a liquid with 3–5 wt.% of pyrolysis oil. The content of DL-limonene in this liquid product was ∼51 wt% and increased further to ∼76 wt% through subsequent ethanol extraction. The fluidized bed reactor (∼510 °C) produced pyrolysis oils with yields around 30–37 wt%. N2 reduced the sulfur content in pyrolysis oil more effective than product gas, due to its dilution effect. The majority of tested desulfurizing additives reduced the sulfur content in pyrolysis oil, and the application of FeO powder and N2 in particular produced pyrolysis oil with the lowest sulfur content (0.39 wt%). Two ex-situ desulfurization methods (ethanol extraction and oxidation/ethanol extraction) were tested to further reduce the sulfur content. The oxidation/ethanol extraction method decreased the content of sulfur in pyrolysis oil to 0.17 wt%.

Solar pyrolysis of scrap tire: optimization of operating parameters

Pyrolysis of scrap tire using concentrated solar radiation is a novel way to upgrade feedstock. In this investigation, best operating condition for maximizing pyro-oil yield was determined. The parameters varied were the temperature of the reactor, flow rate of nitrogen gas and size of the feed particles. The maximum pyro-oil yield was 52 wt% at 400 °C of reactor temperature and nitrogen flow rate of 6 lpm for a feed size of 4 cm3. The pyro-oil and char were characterized according to ASTM standards. This research showed the feasibility of converting scrap tire into pyro-oil by using solar energy via pyrolysis and analysis showed the potential of pyro-oil and char as a valuable source of chemicals.

Characteristics of limonene formation during microwave pyrolysis of scrap tires and quantitative analysis

Using the test system for the microwave pyrolysis of scrap tires, the effects of different factors on the production characteristics of limonene in oils were investigated. The results showed that the optimum processing parameters for the production of limonene were the specific microwave power of 15 W/g, the weight hourly space velocity of 3.75 h−1, the tire particle size of 0.6 mm, and the absence of steel wires. The yield of limonene in the pyrolysis oil under this set of conditions was up to 23.4%. According to the pyrolysis process and the product composition, the mechanism of limonene production under microwave pyrolysis conditions was predicted. The content of limonene in the pyrolysis oil was quantitatively analyzed by an external standard method (ESM) and the peak area normalization method (PANM) separately. The numerical values of the test results obtained by multiplying PANM by the calibration factor of 1.5 equal the corresponding results obtained using the ESM method. Compared with conventional pyrolysis, the microwave pyrolysis of waste tires has a higher yield of limonene under optimized conditions. The results provide an important reference for the high-value utilization of waste tires and the utilization of resources, especially the subsequent production of limonene.

Characterization and controlled combustion of carbonaceous deactivating species deposited on an activated carbon-based catalyst

The composition of the carbonaceous deactivating species (coke) deposited on a Pt and Pd supported P-containing activated carbon catalyst has been studied. These deactivating species were deposited on the catalyst during the hydrocracking of scrap tire pyrolysis oil at 400–500°C, and it has been selectively characterized by means of temperature-programmed oxidation (TPO), temperature-programmed desorption/gas chromatography (TPD/GC) and laser desorption-ionization/mass spectroscopy (LDI/MS). In addition, the evolution of the textural properties and the acidity of the deactivated catalysts have been evaluated. The high thermal and oxidation resistance of the catalytic support has allowed to combust the coke in the TPO and calculate its intrinsic activation energy as a function of the extent of the combustion. Combined TPO and LDI/MS results have shown that an increase in the hydrocracking temperature attenuates the catalyst deactivation due to the hydrocracking of coke precursors. Coke aging, by evolving towards a more condensed structure, is also favored at higher hydrocracking temperatures. The combustion of the most condensed coke requires of higher temperatures than 375°C, which hinders the complete regeneration of the activated carbon-based catalyst.

Durability analysis of a single cylinder DI diesel engine operating with a non-petroleum fuel

Tyre pyrolysis oil (TPO) derived from pyrolysis of scrap tyres has been proven as a source of heat energy. Earlier investigations indicated that, a blend (JMETPO20) comprising of 20% TPO and 80% Jatropha methyl ester (JME) was found to be the optimum blend, when tested in a diesel engine. A comparative study reported in this paper is aimed to examine the durability issues of a direct injection diesel engine run on the JMETPO20 blend and diesel. For this purpose, the engine operated with the JMETPO20 blend and diesel was run for 100h, which consist of 14 test cycles of 7h each as per the IS 10000 standards. Visual examination of the vital parts of the engine components such as cylinder head, piston crown, and nozzle injector tip, etc. was also carried out to find the carbon deposit after the durability test. After the durability test, several tribological characteristics of the used lubricating oil were evaluated after every 25h of engine operation in order to analyze the consequence of fuel chemistry on the life of the lubricating oil. Measurement of different metal debris concentrations present in the lubricating oil samples drawn from the JMETPO20 blend and diesel operated engine was carried out by the atomic absorption spectroscopy.

Novel Catalytic Systems for Waste Tires Pyrolysis: Optimization of Gas Fraction

In this paper, catalyzed pyrolysis of scrap tires was studied in order to identify the influence of catalysts on gas composition during the main thermal range of the decomposition process. The aim is related to gas fraction optimization in terms of yield, composition, and distribution during the pyrolysis process. This is an original work using for the first time powder catalysts (MgO, Al2O3, CaCO3, and zeolite ZSM-5) uniformly distributed on a single layer of oyster shells (OSs) particles. The catalyst/tires mass ratio was kept for all the tests at 1/30. Depending on used catalyst, pyrolysis products yields ranged from 39 to 42 wt.% for char, from 26 to 38 wt.% for oils, and from 16 to 30 wt.% for gas. Compared to the thermal pyrolysis, it was found that the liquid yield increases in the presence of MgO/OS, while the use of Al2O3/OS decreases it significantly. The gas yield grows in the presence of Al2O3/OS ranging from 24.6 wt.% (thermal pyrolysis) to 30.6 wt.%. On the other hand, ZSM-5/OS and CaCO3/OS did not bring significant changes in products yield, but there are considerable influences on the evolution of gas composition during the tires decomposition. Also, two important advantages of using these new catalytic systems are identified. These relate to the formation of gaseous species throughout the waste decomposition, thus harmonizing the calorific value for the entire thermal range, and the disappearance of heavy molecules in liquid fractions, simplifying or canceling further upgrading processes.

Scrap tire pyrolysis using a new type two-stage pyrolyzer: Effects of dolomite and olivine on producing a low-sulfur pyrolysis oil

Scrap tire pyrolysis was performed using a two-stage pyrolyzer consisting of an auger reactor and a fluidized bed reactor to produce a low-sulfur pyrolysis oil. In the experiments, the effect of the residence time of the feed material in the auger reactor was investigated at ∼300 (auger reactor) and 500 °C (fluidized bed reactor). In addition, natural dolomite and olivine and calcined dolomite and olivine were used as the fluidized bed materials to examine their effects on reducing the sulfur content of pyrolysis oil. In the experiments, the yields of the oil from the auger reactor were 1.4–3.7 wt%, and it was enriched with dl-limonene whose content in the oil was 40–50 wt%. The yields of the oil from the fluidized bed reactor were 42–46 wt%. The optimum residence time of the feed material in the auger reactor turned out to be 3.5 min. Calcined dolomite and olivine significantly decreased the sulfur content of pyrolysis oil. Metal oxides of the additives appeared to react with H2S to form metal sulfides. The sulfur content of pyrolysis oil obtained with calcined olivine was 0.45 wt%.

Physico-chemistry properties of fuel blends composed of diesel and tire pyrolysis oil

Pyrolysis of scrap tires has been pointed out as an alternative to the incorrect disposal of tire wastes. Pyrolysis processes can produce tire-derived oils that may be used as fuel or added to conventional fuels, producing fuel blends with improved properties and reduced cost. The pyrolysis process can contribute to remove tire residues of inadequate sites and it can be a sustainable process to produce alternative fuels. In this work, the properties of blends between petroleum diesel and pyrolytic oil obtained from the thermal degradation of tire waste were investigated.The liquid obtained from the tire waste pyrolysis was black oil, possessing a distinctive, unpleasant and strong odor. The compositional analysis of pyrolytic oil describes the liquid as a complex mixture, composed mainly of aromatic compounds and olefins. The oil specific gravity was 0.93gcm−3, while gasoline and diesel showed 0.74 and 0.84gcm−3, respectively. The Research Octane Number (RON) for the pyrolytic oil was found to be similar to the RON for Premium gasoline (higher than 100). Its Motor Octane Number (MON) was found to be slightly lower than the MON for gasoline and very higher than those to diesel fuel. The pyrolytic oil showed also higher detonation resistance in relation to the conventional fuels investigated. The oil has the High Heat Value (HHV) in-between than that for gasoline and diesel fuel, achieving 42kJg−1. The tire pyrolysis oil was miscible with diesel in the entire concentration range. Pyrolysis oil/diesel blends showed properties that make them able to be applied as fuel. However, blend properties highlight the complexity of the chemical interactions between the fuels, which need consideration before their applications.

Derived oil production by catalytic pyrolysis of scrap tires

Scrap tires were pyrolyzed in a continuously stirred batch reactor in the presence and absence of catalysts. The maximum yield of derived oil was up to 55.65 wt% at the optimum temperature, 500 °C. The catalytic pyrolysis was performed using 1.0 wt% (on a scrap tire weight basis) of catalysts based on ZSM-5, USY, β, SAPO-11, and ZSM-22. The oil products were characterized using simulation distillation, elemental analysis, and gas chromatography-mass spectrometry. The results show that using a catalyst can increase the conversion of scrap tires to gas and decrease char by-products; the yield of derived oil remains unchanged or a little lower. The oils derived from catalytic pyrolysis had H/C ratios of 1.55–1.65 and contained approximately 70–75 wt% light oil, 0.3–0.58 wt% S and 0.78–1.0 wt% N. Catalysts with high acid strengths and appropriate pore sizes, such as ZSM-5, USY, β, and SAPO-11, increased the amount of single-ring aromatics in the light-middle-fraction oil to 45 wt%. The derived oil can therefore be used as a petrochemical feedstock for producing high-value-added chemical products or fuel oil.

Optimization of Heat Transfer Characteristics in a Scrap Tire Pyrolysis Reactor using Computational Fluid Dynamics

Optimization of Heat Transfer Characteristics in a Scrap Tire Pyrolysis Reactor using Computational Fluid Dynamics

Non-catalytic pyrolysis of scrap tires using a newly developed two-stage pyrolyzer for the production of a pyrolysis oil with a low sulfur content

The aim of this work was to reduce the sulfur content of pyrolysis oil derived from the scrap tire pyrolysis. In this respect, a series of pyrolysis experiments was conducted in both a fluidized bed reactor (one-stage pyrolysis) and a newly developed two-stage pyrolyzer consisting of an auger reactor and a fluidized bed reactor in series (two-stage pyrolysis). The one-stage pyrolysis was carried out at ∼500 and 600°C with different fluidizing gases (N2 and product gas). In the experiments, the pyrolysis oil obtained at ∼500°C had a lower sulfur content than that produced at ∼600°C. N2 was better at producing a low-sulfur pyrolysis oil than product gas. The sulfur contents of the oils obtained from the one-stage pyrolysis ranged from 0.75 to 0.92wt.%. The two-stage pyrolysis was conducted using product gas as the fluidizing medium at different auger reactor temperatures (∼230–450°C) and at a constant fluidized bed reactor temperature (∼510°C). A pyrolysis oil containing only 0.55wt.% of sulfur could be produced at the temperatures of the auger reactor of ∼330°C and fluidized bed reactor of ∼510°C. Moreover, the two-stage pyrolysis could produce an oil with a low nitrogen content (0.28wt.%). A pyrolysis oil obtained from the auger reactor contained dl-limonene up to 50wt.%.

Kinetic Modeling of the Hydrotreating and Hydrocracking Stages for Upgrading Scrap Tires Pyrolysis Oil (STPO) toward High-Quality Fuels

The upgrading of scrap tires pyrolysis oil (STPO) has been studied in order to produce high-quality alternative fuels, conceived as the second and third stage of an industrially orientated valorization pathway for tires: pyrolysis, hydrotreating, and hydrocracking. The experiments have been carried out in a fixed-bed reactor under the following experimental conditions: (i) for hydrotreating: NiMo/Al2O3 catalyst; time on stream (TOS), 0–8 h; 300–375 °C; 65 bar; H2:oil ratio, 1000 (v/v); space time, 0–0.5 gcat h gfeed–1; and (ii) for hydrocracking: PtPd/SiO2–Al2O3 catalyst; TOS, 0–6 h; 440–500 °C; 65 bar; space time, 0–0.28 gcat h gfeed–1; H2:oil ratio, 1000 (v/v). From the results, lump-based kinetic models have been established for both stages, considering the reactions of (i) hydrodesulfurization (HDS), (ii) hydrocracking (HC), and (iii) hydrodearomatization (HDA) in each one of them. Catalyst deactivation is insignificant in the hydrotreating stage but important for the hydrocracking stage. Therefore, d...

Use of recovered fuel in a piston engine under engine control module modulation in self-fuzzy mode

This study analyses the fundamental characteristics of recovered fuel derived from pyrolysis of scrap tyres. It investigates the differences between diesel and recovered fuel and between their performance characteristic curves. A plug-in engine control module is used in addition to the original engine control module to correct the curves to optimise performance. The feasibility of replacing diesel by recovered fuel is analysed and evaluated. The optimum combustion conditions for mixtures of recovered fuel and conventional diesel and biodiesel are determined. The results of this study can provide a basis for the design of electromechanical regulation systems to allow the use of recovered fuel in future diesel engines.

Analysis of pyrolysis liquid obtained from whole tyre pyrolysis with molten zinc as the heat transfer media using comprehensive gas chromatography mass spectrometry

Pyrolysis of scrap tyres is a promising technology to recover valuable materials such as pyrolysis liquids, carbon black and steel. Pyrolysis liquids are complex mixtures of organic compounds and may represent a valuable source for chemicals. And because pyrolysis liquids are complex mixtures, high resolution analytical methods are required to accurately characterize these liquids. In this study comprehensive gas chromatography mass spectrometry (GC×GC–MS) using a reversed column setup (polar×apolar) was used for the analysis of a pyrolysis liquid. The tyre pyrolysis liquid analyzed was obtained from a process which places whole tyres onto molten zinc (460–480°C) providing direct heat transfer and hence rapid pyrolysis. The results show, that the pyrolysis liquid is a complex mixture of acyclic and cyclic, aliphatic, unsaturated and aromatic hydrocarbons and several heteroatomic compounds. Compared to a normal column setup (apolar×polar), the reversed column setup separates structurally similar acyclic and cyclic hydrocarbon compounds with different degree of unsaturation better. A quantification was performed for a set of 40 compounds. A qualitative and quantitative evaluation of the compounds found, that the composition of the pyrolysis liquid is typical for tyre pyrolysis liquids. Nevertheless, comparably high amounts of limonene of 6.6% (w/w) and low amounts of monocyclic aromatic compounds were found. This is attributed to the very high heating rate of this process due to the direct heat contact of the tyres with molten zinc.

Prospects for Obtaining High Quality Fuels from the Hydrocracking of a Hydrotreated Scrap Tires Pyrolysis Oil

The hydrocracking of hydrotreated scrap tires pyrolysis oil (HT-STPO) has been studied aiming at high-quality refinery blends for alternative automotive fuels. The hydrocracking runs have been carried out with a PtPd/SiO2-Al2O3 catalyst in a fixed-bed reactor at 440–500 °C, 65 bar and space time of 0.16 h. The catalyst has been characterized by inductively coupled plasma optical emission spectroscopy, N2 adsorption–desorption isotherms, and tert-butylamine adsorption–desorption (TPD), while coke has been studied both quantitatively and qualitatively by thermogravimetric-temperature-programmed oxidation (TG-TPO), Fourier transform infrared-TPO, and Raman spectroscopy. During the first two hours of reaction and at temperatures above 480 °C, we have been able to (1) reach ultra low sulfur levels lower than 15 ppm; (2) remove almost completely the less interesting fraction—boiling points higher than 350 °C, named as the gasoil fraction—with remaining amounts lower than 1 wt %; (3) obtain a paraffinic and isop...

Production of Oil and Char by Intermediate Pyrolysis of Scrap Tyres: Influence on Yield and Product Characteristics

Abstract Scrap tyres represent a severe environmental problem that must be solved by developing technologies allowing the processing of high quantities of this residue. This work presents the results of pyrolysis oil and pyrolytic char production by intermediate pyrolysis of rubber recovered from scrap tyres. The influence of process variables such as particle size, temperature and reaction time on the characteristics of the products obtained was analysed. Maximal yields of 52.56 and 39.50 wt% of pyrolysis oil and pyrolytic char, respectively, were obtained, under operational conditions that favoured the production of pyrolysis oil. The products obtained were a pyrolytic char with a maximal surface area of 85.16 m2/g and fixed carbon content of 78.55 wt%; and pyrolysis oil with a higher heating value of 42.94 MJ/kg, real density of 0.948 g/mL, viscosity 2.29×10−3 Pa s and acidity between 0.39 and 1.57 mg KOH/g. The highest total aromatics (benzene, toluene, xylenes and ethylbenzene) yield in pyrolysis oil was obtained at a temperature of 466°C and volumetric gas flow of 155 NmL/min. In addition, at these conditions, the pyrolysis oil having the maximum aromatic yield showed the lowest acidity. Nevertheless, it was observed that the highest pyrolysis oil yield does not necessarily lead to a higher yield of aromatics.

Upgrading model compounds and Scrap Tires Pyrolysis Oil (STPO) on hydrotreating NiMo catalysts with tailored supports

The upgrading of Scrap Tire Pyrolysis Oil (STPO) has been studied in order to remove undesired sulfur, nitrogen and unsaturated compounds while improving the properties of its different fractions (naphtha, diesel and gasoil) toward being used as a potential blend in the refinery. The studied catalysts are NiMo supported on 5 porous materials: γ-Al2O3 (ALM catalyst), SiO2–Al2O3 (ASA), SBA-15 (SBA), MCM-41 (MCM) and an equilibrated FCC catalyst (FCC). The hydrotreating runs have been carried out in a fixed bed reactor at 275–375°C and 65bar. The catalysts were characterized by ICP-AES, N2 adsorption–desorption isotherms, H2 chemisorption, XRD, XPS, TPR and terc-butylamine adsorption–desorption (TPD). A preliminary catalyst screening with a model mixture of representative STPO compounds has been performed for selecting the most active catalysts: ALM, ASA and MCM catalysts ensured the 99.9% removal of sulfur. Secondly and in the hydrotreating of STPO, our results point the suitability of ASA catalyst for obtaining the highest proportion of naphtha (25wt%) and diesel (57wt%), ALM catalyst for increasing the yield of paraffins and the cetane number in diesel, and the promising performance of MCM catalyst for facilitating internal mass transfer.

Analysis of high molecular weight compounds in pyrolysis liquids from scrap tires using Fourier transform ion cyclotron resonance mass spectrometry

Liquids from the pyrolysis of scrap tires are known to be mixtures of a huge variety of organic molecules ranging from low to high boiling compounds. While the low to medium boiling fraction has been investigated using gas chromatography, virtually no information exists regarding high molecular weight compounds. Although size exclusion chromatography has been used to prove their existence no structural information has been obtained yet. In this study Fourier-transform ion-cyclotron-resonance mass-spectrometry (FT-ICR-MS) using laser desorption ionization (LDI) was applied to analyze the high molecular weight fraction of pyrolysis liquids from a fixed bed reactor. Samples were prepared as graphite slurry on conventional steel target plates and mass spectra were compared to those obtained from preparations without graphite. The influence of the graphite to sample ratio and the impact of laser fluence were examined. Using graphite as support during laser desorption increased the spot capacity and enabled the acquisition of a multitude of scans which significantly increased S/N ratios and led to the identification of a range of hydrocarbon and heteroatomic molecular formulas. Molecular formulas of highly unsaturated hydrocarbon compounds with 35–70 carbon atoms and compounds of the type CcHhOoNnSs with o = 0,…,2, n = 0,…,1 and s = 0,…,1 could be identified.