Tire Char Research Articles

Synergetic Effect of Steam and Activated Tyre Char on the Selective Production of Levoglucosan-Rich Bio-Oil from Catalytic Pyrolysis

Synergetic Effect of Steam and Activated Tyre Char on the Selective Production of Levoglucosan-Rich Bio-Oil from Catalytic Pyrolysis

Effect of Pyrolysis Atmosphere on the Gasification of Waste Tire Char

The aim of the study is to assess the influence of the atmosphere during pyrolysis on the course of CO2 gasification of a tire waste char. Two approaches were used: the pyrolysis step was carried out in an inert atmosphere of argon (I) or in an atmosphere of carbon dioxide (II). The examinations were carried out in non-isothermal conditions using a Rubotherm DynTherm thermobalance in the temperature range of 20–1100 °C and three heating rates: 5, 10 and 15 K/min. Based on the results of the gasification examinations, the TG (Thermogravimetry) and DTG (Derivative Thermogravimetry) curves were developed and the kinetic parameters were calculated using the KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa) methods. Additionally, the CO2 gasification of tire chars reaction order (n), was evaluated, and the kinetic parameters were calculated with the use of Coats and Redfern method. Tire waste char obtained in an argon atmosphere was characterized by lower reactivity, which was reflected in shift of conversion and DTG curves to higher temperatures and higher mean values of activation energy. A variability of activation energy values with the progress of the reaction was observed. For char obtained in an argon atmosphere, the activation energy varied in the range of 191.1–277.2 kJ/mol and, for a char obtained in an atmosphere of CO2, in the range of 148.0–284.8 kJ/mol. The highest activation energy values were observed at the beginning of the gasification process and the lowest for the conversion degree 0.5–0.7.

Assessment of the catalytic effect of various biomass ashes on CO2 gasification of tire char

The aim of this study was to determine the effect of various biomass ashes, comprising catalytically active components, on tire char reactivity during the CO2 gasification process. Ashes from the combustion of corn cobs, beet pulp, sunflower husks and beech chips were selected for the research. Moreover, industrial fly ash from a coal-fired power plant was used as a reference. The tire char-ash blends with different ash contents (0–15 wt%) were gasified in the CO2 atmosphere under non-isothermal conditions using dynTHERM Rubotherm thermobalance. Based on the n-order Coats and Redfern method, gasification reactivity indicators and kinetics parameters were calculated. The results showed that the addition of biomass ashes enhanced reactivity of tire char, and the magnitude of these changes depended on both the quantity and type of the additive. With the increase in the amount of added biomass ashes, the catalytic effect increased, and their efficiency can be ranked as follows: sunflower husk ash > corn cobs ash ≅ beet pulp ash > beech chips ash. In turn, reference fly ash from a power plant slightly affected the CO2 gasification of tire char, regardless of its amount. Moreover, a statistically significant correlation between the reactivity indicator and the amount of K2O, MgO and P2O5 in ashes analysed has been proved (reactivity indicator improved with an increase in these components amount). The performed analysis provides valuable information regarding the composition of catalysts characterised by high catalytic activity in the tire char gasification process.

Thermal properties of a cement composite containing phase change materials (PCMs) with post-pyrolytic char obtained from spent tyres as a carrier

This work examines the possible use of post-pyrolysis char made from spent vehicle tyres as a carrier for phase change materials (PCM), which could be used as an additive to cement mortar. Because of the ability of PCM to accumulate heat, the cement composite obtained from it, apart from its structural and strength properties, will acquire an additional energy storage function, which can be very important for energy-saving construction.In the development of the new cement composite, Rubitherm RT22 was used as a PCM. Rubitherm's phase change temperature is within the range (ca 17–25 °C) of temperature fluctuations in buildings. Systematic comparative tests were carried out in order to evaluate the thermal properties of the new cement composite containing 0.67, 2.00, 3.33, 4.67 and 6.67% of char, which contains 32% PCM, i.e. the maximum amount that can be permanently absorbed without activation. These tests included calorimetric measurements of the influence of the composite's composition on the cumulative specific heat, and took phase change effects into consideration.The results of the experiments showed that the use of tyre char as a PCM carrier in cement mortars is not only possible, but also thermodynamically advantageous.

Adsorption of pharmaceuticals in a fixed-bed column using tyre-based activated carbon: Experimental investigations and numerical modelling

Magnetic tyre char (MTC), activated tyre char (ATC) and commercial activated carbon (CAC) were used as packing materials in lab-scale column study for the adsorption of three pharmaceuticals: propranolol (PRO), ciprofloxacin (CIP) and clomipramine (CLO), from aqueous solution. The obtained breakthrough curves (BTCs) suggest that, lower flow rate, greater bed height, higher pH and nano particle size led to increased adsorption of PRO. The lowest adsorption capacity was observed for CIP either from single or ternary solution while it was significantly higher for CLO. Surface area of ATC increased nearly twelve-fold (38.17 to 453.81 m2/g), after thermal and chemical activation and adsorption capacity was comparable to commercial activated carbon. The suitability of Hydrus-1D model incorporating chemical non-equilibrium process to simulate the pharmaceutical transport and fit experimental BTCs was demonstrated (97.29 <R2 <99.22) in comparison to other common models (Adams–Bohart, Thomas and Yoon–Nelson). The modelling suggests the existence of non-equilibrium conditions and rate-limited sorption sites and the effect of dispersion and mass transfer mechanisms in the solute transport under dynamic conditions. The cost analysis showed that unit cost for treatment of wastewater using fixed-bed columns of tyre char was calculated to be 1.57 US$/m3 which can be deemed as commercially feasible.

Waste tyre char-catalysed in-situ deoxygenation of volatile vapours and production of hydrogen-rich syngas during the pyrolysis of lignite

This paper examined the catalytic performance of tyre char, a waste-derived product on the catalytic pyrolysis of lignite at 600-900 °C, upon the use of different gas environment (i.e. argon versus steam) and different catalyst to lignite mass ratio. All the resultant products (solid, gas and liquid) and spent catalysts have been characterised intensively to elucidate the specific catalytic role of tyre char and the respective mechanisms. As has been confirmed, the tyre char rich in zinc sulphide is a strong Lewis acid that is able to catalyse the upgrading of lignite volatiles via decarbonylation and steam-reforming of the volatile vapours. The former reaction mainly refers to the conversion of aldehydes to alkanes, whilst the latter one is preferentially implemented for the long-chain heavy hydrocarbons that are prone to deposit on the tyre char surface. The presence of steam in the pyrolysis gas environment promotes the steam-reforming of volatiles and steam-gasification of char, but also enhances the acidity strength for the formation of intermediate SO active site that is responsible for the adsorption of O-bearing volatiles and the dissociation of steam. The enhancement of Lewis acid on catalyst surface is also highly sensitive to the mass of catalyst and the extent of its exposure to the O-bearing species including steam and volatile vapours. The use of large quantity such as three times larger than the lignite are essential for the tyre char to remain highly active upon cyclic usage. An extra activation is also essential after each use. In addition, it is confirmed that the catalytic effect of tyre char is profound for the upgrading of volatile vapours released from fast heating of lignite above 700 °C. At 800 °C, the resultant synthesis gas from lignite is also highly rich in H2 and CO than that reported from the upgraded biomass volatiles based on the use of tyre char. A larger H2 yield was also confirmed for the lignites tested here, due to the abundance of long-chain heavy hydrocarbons derived from them.

Application of high-grade carbon produced from tyre waste using advanced thermo-chemical technology

Abstract Advanced thermo-chemical treatment in inert environment (also known as pyrolysis) of end of life tyres results into generation of oil, non-condensable gases and carbonized product termed as char. Solid char accounts to 35–45 wt% of the total products depending upon the process conditions. The present study is directed towards evaluating the suitability of tyre char for certain commercial applications. Char contains additives (inorganics) which are used to enhance certain properties of commercial tyres. Characterization of char confirms the presence of 19% inorganics that constitutes of elements such as Zn, S, Mg, Si and Ca. The other characterization techniques such as Raman, SEM and TGA have assisted in examining the surface characteristics and stability of tyre char. Raman analysis has emphasized on the presence of graphitized carbon structure with lesser defects. TGA analysis has showed suitable thermal stability at higher temperatures. The direct application of tyre char without further treatment has been undertaken based on these analyses. Char obtained from tyre pyrolysis was evaluated in Styrene Butadiene Rubber based compounding formulation at a dose of 50 parts per hundred gram of Rubber in comparison with a standard carbon black grade of Semi Reinforcing type of carbon black with equivalent dose. It was found that the increase in tensile strength and associated properties of vulcanization of char sample and the char can be utilized in rubber products formulation without any negative impact. Significant improvement was observed on tear strength properties while adding the char or carbon black which proves that there exists the reinforcing characteristics of the char like standard carbon black. Based on these studies, it has been concluded that there is need for further upgradation of tyre char for application in dyes, coatings and activated carbon industries.

Waste tire carbon in synergetic interaction with spent gamma radioactive source for efficient radiocatalytic degradation of organic dye

Enhanced degradation of organic dye was achieved using two different kinds of waste materials: waste tire granules and spent sealed radioactive sources. Waste tire granules were used as raw material for the production of waste tire char (WTC), which was further utilized as an adsorbent matrix for synergetic adsorption/irradiation degradation of organic dye. The spent radioactive sources were radiographic sealed sources that originate from the industry which generate the high energy radiation. Methylene Blue (MB) was used as an organic model compound. Synthesized WTC has turbostratic structure, irregular shaped particles and developed mesoporous surface. Complete degradation of 0.02 dm3 of 100 mg dm−3 MB solution, having WTC dose of 1.25 g dm−3, was achieved with delivered doze of only 60 Gy. The applied doses were 100 times smaller than those presented in the literature. Degradation pathway was determined: OH radicals that originate from radiolysis of water and from the surface of WTC played the crucial role in the radiocatalytic degradation of MB. Breakage of the aromatic ring of MB appeared by the scission of the double C‒S+˭C bond as a result of the attack of OH species on adsorbed and electronically reorganized MB molecule.

Selective deoxygenation of biomass volatiles into light oxygenates catalysed by S-doped, nanosized zinc-rich scrap tyre char with in-situ formed multiple acidic sites

In this paper, we report the unique properties and catalytic performance of scrap tyre char, an otherwise low-value waste derivative on the selective deoxygenation of biomass volatiles (derived from flash pyrolysis of lignocellulosic biomass at 500 °C) into value-added light oxygenates including furfural and phenol. Due to the inclusion of sulphur (S) and zinc oxide (ZnO) as additives during the prior tyre manufacturing process, the pyrolysis-derived tyre char is rich in both organically bound S and nano-sized zinc sulphide (ZnS) that are highly dispersed within the carbonaceous matrix. Detailed characterisations of the fresh and spent catalysts have been conducted to elaborate the unique mechanisms, upon the use of XPS, TEM-SAED, XAS, NEXAFS, Pyridine-FTIR, and NH3-TPD. As has been confirmed, multiple acidic sites are present in tyre char, including organically bound S serving as a weak Brønsted acid and nano-sized ZnS being a strong Lewis acid. The former acid is active for dehydration, whilst the latter one mainly catalyses the decarboxylation and decarbonylation reactions. Upon the interaction with adsorbed oxygen-bearing species and water molecules, the ZnS-centered active acid site can in-situ transform into a ZnSOx-centered super strong acid site, which is a Brønsted acid that is able to enhance the deoxygenation extent remarkably. More interestingly, the organic S enables an in-situ sulphidation of the less active ZnO on the catalyst surface, thereby enabling a continuous exposure of bio-oil vapour to the highly active ZnS and its sulphate derivative. This in turn enlarges the lifetime of the catalyst and its strong stability upon cyclic tests.

Investigation of synergy and inhibition effects during co-gasification of tire char and biomass in CO2 environment

This study investigates the co-gasification of tire char (TC), as a low-quality side-product of scrap tire pyrolysis, and rambutan peel (RP). The objective of this study was to comprehend any synergistic/antagonistic effects during the co-gasification of TC/RP. For this, co-gasification of TC and RP (85:15, 70:30, 50:50, 30:70, and 15:85 wt% of TC:RP) was conducted in CO2 environment by non-isothermal thermogravimetric method. The samples were heated (15 K/min) under N2 to 923 K and then under CO2 to 1400 K. Comparison of the observed and theoretical results indicated the incidence of antagonism in blends with high proportion of TC (e.g., 85%TC–15%RP and 70%TC–30%RP), possibly attributing to the high content of acid oxides (SO3 (30.1%) and SiO2 (24.8%)) in the TC-ash which could inhibit the gasification by formation of inactive silicates in the presence of alkali/alkaline earth metal-rich biomass. In blends with higher content of biomass (e.g., 30%TC–70%RP and 15%TC–85%RP), the actual gasification rates were higher than the theoretically predicted ones showing the presence of a synergism associated with the natural catalysts (K2O (40.6%) and CaO (42.3%)) in RP-ash. Activation energy and thermodynamic studies confirmed the profound effect of biomass on enhancing the reactivity of TC in reaction with CO2. These promoting effects of biomass were associated with its considerably higher alkali index (133.4) than tire (5.6), its less graphitic structure with more structural defects, and imperfections compared with TC. According to the results, the inherently low reactivity of TC in gasification can be accelerated by co-feeding of biomass with TC.

An Investigation into the Applicability of Pyrolyzed Tyre Char and Tyre Crumb for the Recovery of Gold from Acidic Solutions

The present study has assessed the performance of pyrolytic tyre char and tyre crumb as cheap adsorbents for gold recovery from acidic solutions. The performances of the aforementioned cheap adsorbents, prior to and after undertaking demineralisation operations, were also investigated. Demineralisation of the adsorbents was undertaken via the application of 1 M sodium hydroxide and 1M nitric acid at a temperature of 90 °C for a duration of 24 h with changes in BET surface areas (SBETs) and adsorption performances, subsequently evaluated. Initial investigations established that the pH value of 2 constituted the preferred pH at which adsorption was enhanced, thus this pH was maintained while undertaking subsequent kinetic and equilibrium adsorption experiments. Based on the experimental investigations, it was demonstrated that the kinetics and adsorption of gold ions (Au3+) as AuCl4− anions from acidic solutions was best described using pseudo second order kinetic and Langmuir equilibrium isotherm models, respectively. Even though the demineralisation process resulted in a notable increase in BET surface areas (SBETs) for both char (23%) and crumb (984%), it was found to negatively influence adsorbent loading of Au3+ ions onto the adsorbents. It was therefore suggested that sulphur removal via demineralisation may explain the reduced adsorbent loading since there is typically an affinity of gold ions (Au3+) for localised elemental sulphur. This affinity causes sulphur to be oxidised into solution and the gold ions (Au3+) to be reduced to elemental gold on the adsorbent surface. The present study was therefore able to demonstrate the preference for untreated of pyrolytic tyre char and to a lesser extent, untreated crumb, as alternative low-cost adsorbents for gold recovery from acidic solutions.

Effect of Tire-Char Ash on the Extent of Synergy during CO2 Cogasification with Hydrochar from Potassium-Rich Coconut Fiber

The influence of inherent tire-char ash during cogasification with coconut hydrochar prepared at different intensities was investigated by thermogravimetric analysis to ascertain the extent to which synergistic interaction, reactivity, and activation energy reduction were altered. High-ash tire tread (TT) and low-ash sidewall (SW) both exhibited enhanced synergy, reactivity, and activation reduction upon cogasification with hydrochars; however, the extent of promotion was more pronounced in SW–hydrochar blends. This difference was caused by the inhibiting nature of TT inherent ash, particularly the role of Si-containing compounds. Inhibition in TT–hydrochar blends was mainly due to the promotion of alkaline and alkaline earth metal transformation into inactive silicates and, to a lesser extent, the mass transfer effect caused by accumulated ash, especially at conversions higher than 70%. The extent of enhancement correlated well with the concentration of available alkaline and alkaline earth metals. The findings may be useful in justifying the exclusion of high-ash tire char as gasification feedstock to mitigate ash-related problems.

Analysis of selected mineral and waste sorbents for the capture of elemental mercury from exhaust gases

Abstract Several mineralogically, chemically and texturally diverse minerals and waste materials were selected for the testing of elemental mercury capture in exhaust gas, namely tyre char resulting from the burning of pyrolytic rubber tyres, class C fly ash, mesoporous material type MCM-41 and glauconite. Each material’s mineralogical, chemical and textural characteristics were explored. In order to conduct experiments in conditions similar to those during the contact of sorbent with real coal exhaust fumes at a temperature of about 110-120°C, the experiments were carried out using a test device consisting of a furnace for burning powdered coals, a thermostatic cage for sorbent reactors and mercury gas analysers, which are able to measure and compare the effects of individual sorbents with exhaust gas. The study found that the best results for mercury sorption in the exhaust atmosphere were obtained for class C ash resulting from brown coal combustion.

Kinetics and Physicochemical Morphology Evolution of Low and High-Ash Pyrolytic Tire Char during CO2 Gasification

The heterogeneity of waste tire pyrolytic char associated with ash composition and distribution is explored to understand the effect of ash on gasification. In this paper, high-ash tire tread (TT) ...

Kinetics underpinning the C-CO2 gasification of waste tyre char and its interaction with coal char upon co-gasification

This study includes a thorough investigation of the char structure, the potential catalytic influence of minerals, the carbon conversion rate, the kinetic behavior and parameters of the CO2 – gasification reaction for waste scrap tyre char and its blends with coal chars. Kinetic modelling was also attempted based on the two classical methods, random pore model (RPM) and grain model (GM) using the isothermal gasification results collected from thermogravimetric analysis (TGA). As has been found, tyre char is characterised with a macroporous structure with a very low reactivity. The catalytic role of the inherent minerals within tyre char is only influential at lower temperatures below ~1373 K. As opposed to the generally assumed first order reaction, the tyre char exhibits a reaction order between 0.62 (for an intrinsic reaction at 1273 K) and 0.92 referring to a dominant diffusion control at 1573 K. The slow intrinsic reaction rate of tyre char was also found to be comparable with the gas diffusion rate, thereby exhibiting a large activation energy of 174.87 kJ/mol that is considerably higher than coal chars. The coal char – tyre char blends displayed declining reactivity with increasing tyre char content, due to the enhanced ash melting and diffusion against the inward gas diffusion towards the unreacted carbon that is encapsulated inside. This was further explained by the experiments of blending tyre char ash with coal chars, and the observation of ash residues collected from the gasification of blends. Furthermore, the grain model was found more suitable to fit the blending conversion data, agreeing with the hypothesised molten ash layer surrounding the unreacted char blend.

Removal of mixture of phenolic compounds from aqueous solution by tire char adsorption

The article presents the results of the pyrolysis products from waste tires. Pyrolysis was meted out at (400-800°C) for 2 hr in absence of oxygen. The yield of char range from (0.479 - 0.3104). By chemical treatment of char with NaOH solution the modified char was produced. The physical and chemical properties were studied (optimum temperature, proximate analysis and Boehm titration for surface functional groups) for original and modified chars. Isotherm for pure and multicomponent system for three components (phenol, 4-aminophenol and 4-chlorophenol) were studied. The Langmuir and Freundlich models were used to describe the sorption of phenolic compounds for single-solute isotherms and the modified extended Langmuir and extended Freundlich gave information results for competitive system. Langmuir model was the best fit for experimental results. The capability of the studied char to adsorb phenols were in the order: 4-chlorophenol > 4-aminophenol > phenol.

Investigation of synergism and kinetic analysis during CO2 co-gasification of scrap tire char and agro-wastes

Tire char (TC), the by-product of waste tire pyrolysis, suffers from low reactivity in CO2 gasification reaction due to high content of acid oxides in its ash and its graphitic structure, with low degree of structural conformations. To address this limitation, TC was co-gasified with several biomass residues including cattle manure (CM), palm empty fruit bunch (EFB), almond shell (AS) and rubber seed shell (RSS). The CO2 gasification reactivity of the TC/biomass blends was investigated at different heating rates by non-isothermal thermogravimetric method. Results signified the incidence of synergy during CO2 gasification of TC/biomass blends where the reactivities of blends were superior to that of individual TC. This was attributed to the inherent alkali and/or alkaline earth metals of biomass fuels acting as natural catalysts to enhance the gasification rate of TC. Several isoconversional kinetic methods also confirmed the occurrence of synergism in blends where the activation energy of all blends in CO2 gasification reaction was lower than sole TC (238 kJ/mol), with TC/CM blend (172 kJ/mol) leading other combinations. Thermodynamic studies also revealed that blending of TC with biomass was effective to improve the reaction rate of TC with CO2 and favorability of the reaction.

Gasification of Municipal Solid Waste Using Tyre Char as Catalyst

Gasification is raised as the most promising technologies of municipal solid waste (MSW) removal as well as energy recovery. The principal problem related with the gasification process is the high amount of tar released during the gasification process that causes environmental and operational problems. The purpose of this study is to investigate the performance of MSW gasification using tyre char as an alternative option for catalytic gasification to produce tar free clean gas. Catalytic performance of tyre char was compared with performance of MSW gasification alone without the tyre char in a bench scale downdraft reactor. The waste tyre char removed 80% of tars in syngas at 700 °C. Analysis of the syngas compositions indicated that concentration of H2 and CO were significantly increased. Therefore, it was concluded that chars especially tyre char can be an effective and inexpensive catalyst for tar removal and syngas production of MSW gasification.

Catalytic performance of scrap tyre char for the upgrading of eucalyptus pyrolysis derived bio-oil via cracking and deoxygenation

Catalytic pyrolysis of biomass is one of the potential routes to convert lignocellulose material to high-value bio-fuels. In this paper, we explored the use of Zn-rich scrap tyre char, a low-value byproduct from the pyrolysis of waste scrap tyre as a catalyst for in-situ upgrading of crude bio-oil derived from the pyrolysis of eucalyptus. Experiments were performed in a two-stage fixed-bed reactor at 500 °C with a catalyst loading of 0–80 wt% on the mass basis of biomass. The characteristics of catalyst and bio-oils were conducted extensively by different facilities, including Karl Fischer titration, XRF, CHNS, FTIR, solvent extraction, and synchrotron C K-edge XANES. A removal of 40.3% oxygen in the form of H2O, CO2 and CO was confirmed upon the loading of 80 wt% scrap tyre char. Simultaneously, the bio-oil yield decreased from 33.4 wt% to 21.1 wt%. The acid-soluble inorganic species in scrap tyre char preferentially cracks the heavy hydrocarbons, thereby decreasing the yields of heavy pitch and coke. The catalyst loading is critical, triggering a rapid increase in the cracking/deoxygenation extent upon increasing the catalyst loading to 40 wt%. Afterwards, the change on the extent of deoxygenation is marginal. Based on the gaseous products, the content of CO2 is the highest, confirming the preferential decarboxylation catalysed by scrap tyre char. In contrast, the amount of CO derived from decarbonylation reaction is nearly unchanged, suggesting an insignificant effect of scrap tyre char on this deoxygenation reaction. The catalytic performance of tyre char was also found comparable to and even slightly better than the zeolitic catalysts tested under the similar conditions in the literature. However, its catalysis mechanism is fully unknown. The abundant ZnS within tyre char has yet to be reported as a catalyst for bio-oil deoxygenation. This inorganic species is even deeply embedded and inaccessible to acid washing within the tyre char. Investigation on its detailed structure and transformation for the catalysis reactions with bio-oil are underway.

Hydrogen-rich syngas production and tar removal from biomass gasification using sacrificial tyre pyrolysis char

Carbonaceous materials have been proven to have a high catalytic activity for tar removal from the syngas produced from biomass gasification. The simultaneous reforming and gasification of pyrolysis gases and char could have a significant role in increasing the gas yield and decreasing the tar in the product syngas. This study investigates the use of tyre char as a catalyst for H2-rich syngas production and tar reduction during the pyrolysis-reforming of biomass using a two stage fixed bed reactor. The biomass sample was pyrolysed under nitrogen at a pyrolysis temperature of 500°C, the evolved pyrolysis volatiles were passed to a second stage with steam and the gases were reformed in the presence of tyre char as catalyst. The influence of catalyst bed temperature, steam to biomass ratio, reaction time and tyre ash metals were investigated. The influence of the catalytic activity of tyre ash minerals on composition of syngas and tar decomposition during the steam reforming of biomass was significant as the removal of minerals led to a decrease in the H2 yield. Raising the steam injection rate and reforming temperature resulted in an increase in H2 production as steam reforming and char gasification reactions were enhanced. The maximum H2 content in the product syngas of 56vol.% was obtained at a reforming temperature of 900°C and with a steam to biomass mass ratio of 6 (g/g). Further investigation of the influence of the biomass:steam ratio on syngas quality showed that the H2:CO molar ratio was increased from 1.8 (steam: biomass ratio; 1.82gg−1) to 3 (steam: biomass ratio; 6gg−1).