Evaluation of two different scrap tires as hydrocarbon source by pyrolysis

The main objective of the present study is to investigate the effect of the polymer types in scrap tires on the pyrolysis products. Two different types of scrap tires (passenger car tire, PCT and truck tire, TT) have been pyrolyzed in a fixed bed reactor at the temperatures of 550, 650 and 800 °C under N₂ atmosphere. Pyrolysis products (gas, oil and carbon black) obtained from PCT and TT were investigated comparatively. The gaseous products were analyzed by GC–TCD. The psychical and chemical properties of pyrolytic oils were characterized by means of GC–FID, GC–MS, ¹H NMR. In addition, boiling point distributions of hydrocarbons in pyrolytic oils were determined by using simulated distillation curves in comparison with commercial diesel fuel. The production of activated carbon from pyrolytic carbon blacks (CBp) was also carried out. The composition of gaseous products from pyrolysis of PCT and TT were similar and they contained mainly hydrocarbons (C₁–C₄). Pyrolytic oils were found lighter than diesel but heavier than naphtha. The physical properties of pyrolytic oils from PCT and TT were similar at the same temperature. However, the composition of aromatic and sulphur content from pyrolysis of PCT was higher than that of TT. Furthermore, TT derived pyrolytic carbon black was found more suitable for the production of activated carbon due to its low ash content.     

Characterization of sucrose polyesters-triacylglycerols mixtures

High-performance size-exclusion chromatography (HPSEC) and thin-layer chromatography/flame-ionization detection (TLC/FID) have been used for the characterization of mixtures of either monoacid sucrose octaesters with triacylglycerols (TAG) or sucrose polyesters (SPE) prepared from oils with natural oils. In mixtures of monoacid sucrose octaesters/TAG, no significant differences were found between the values obtained by either HPSEC or TLC/FID and the actual component proportions. Additionally, components could be separated by TLC, which was confirmed by fatty acid composition data of each fraction. Analysis of SPE/oil mixtures was attainable by HPSEC, but alternative quantitation by TLC/FID required previous silylation. Likewise, fatty acid composition could be determined only in the total mixture and in the sucrose octaester fraction. A formula derived for calculation of oil fatty acid composition, based on analytical data, showed the validity of the approach used in this study to determine component proportions in functional SPE/oil mixtures.     

Pyrolytic characteristics of Jatropha seedshell cake in thermobalance and fluidized bed reactors

Pyrolytic kinetic parameters of Jatropha seedshell cake (JSC) were determined based on reaction mechanism approach under isothermal condition in a thermobalance reactor. Avrami-Erofeev reaction model represents the pyrolysis conversion of JSC waste well with activation energy of 36.4 kJ mol^?1 and frequency factor of 9.18 s^?1. The effects of reaction temperature, gas flow rate and feedstock particle size on the products distribution have been determined in a bubbling fluidized bed reactor. Pyrolytic bio-oil yield increases up to 42 wt% at 500 °C with the mean particle size of 1.7 mm and gas flow rate higher than 3U _mf , where the maximum heating value of bio-oil was obtained. The pyrolytic bio-oil is characterized by more oxygen, lower HHVs, less sulfur and more nitrogen than petroleum fuel oils. The pyrolytic oil showed plateaus around 360 °C in distribution of components’ boiling point due to high yields of fatty acid and glycerides.     

The thermoplasticity of coal and the effect of K2CO3 addition in relation to the reactivity of the char in gasification

The thermoplastic properties of a medium-volatile and a high-volatile A bituminous coal have been studied by means of high-pressure dilatometry as a function of the heating rate (10 and 65 K min⁻¹), particle size (< 44 μm, < 75 μm, 106–200 μm and 212–400 μm) and gas pressure (1–28 bar). The thermoplastic properties of the coals are significantly different at elevated pressures from those at atmospheric pressure. At atmospheric pressure the volume swelling increases strongly with increasing heating rate and, at 10 K min⁻¹, with increasing particle size. At a pressure of 28 bar however, the swelling is nearly independent of heating rate and particle size. The effect of addition of K₂CO₃ (20% by weight) was investigated at 65 K min⁻¹ and turned out to depend on the gas pressure and particle size. At atmospheric pressure, K₂CO₃ reduces the dilatation of the coals almost completely. This reduction decreases with increasing pressure, especially for the larger particle size fraction (212–400 μm). A detailed mechanism for the interaction of alkali metal carbonates with the coal is suggested. The softening and swelling of coal particles has consequences for the available and accessible surface area of the char formed and thus for the reactivity of the char in gasification. Results of reactivity measurements in a CO₂ atmosphere in a thermobalance that illustrate this effect are presented and related to the morphology of the char.     

Synthetic coal chars for the elucidation of NO heterogeneous reduction mechanisms

In the present work, the mechanisms involved in NO–char heterogeneous reduction have been studied using a synthetic coal char (SC char) as carbon source. Another synthetic char (SN char) without nitrogen in its composition has also been employed in these studies. Isothermal reduction tests at different temperatures have been carried out. Two temperature regimes were considered: low temperature (T < 250 °C) where NO chemisorption takes place and high temperature (T > 250 °C) where NO–C reaction occurs. Step response experiments combining consecutive reaction stages with NO and ¹⁵NO were performed in order to determine the role of nitrogen surface complexes, C(N), in the reduction process. The results revealed N₂ and CO₂ to be the main reduction products under the experimental conditions employed in this work. NO chemisorption at lower temperatures results in N₂ emission and surface complexes (mainly oxygenated) formation, while char gasification by NO involves a direct NO attack on the char surface to form surface complexes. As a consequence of desorption of these complexes new sites of reaction are created.     

The pyrolysis of scrap automotive tyres: The influence of temperature and heating rate on product composition

Shredded automotive tyre waste was pyrolysed in a 200 cm³ static batch reactor in a N₂ atmosphere. The compositions and properties of the derived gases, pyrolytic oils and solid char were determined in relation to pyrolysis temperatures up to 720 °C and at heating rates between 5 and 80 °C min⁻¹. As the pyrolysis temperature was increased the percentage mass of solid char decreased, while gas and oil products increased until 600 °C after which there was a minimal change to product yield, the scrap tyres producing approximately 55% oil, 10% gas and 35% char. There was a small effect of heating rate on the product yield. The gases were identified as H₂, CO, CO₂, C₄H₆, CH₄ and C₂H₆, with lower concentrations of other hydrocarbon gases. Chemical class composition analysis by liquid chromatography showed that an increase in temperature produced a decrease in the proportion of aliphatic fractions and an increase in aromatic fractions for each heating rate. The molecular mass range of the oils, as determined by size exclusion chromatography, was up to 1600 mass units with a peak in the 300–400 range. There was an increase in molecular mass range as the pyrolysis temperature was increased. FT-i.r. analysis of the oils indicated the presence of alkanes, alkenes, ketones or aldehydes, aromatic, polyaromatic and substituted aromatic groups. Surface area determination of the solid chars showed a significant increase with increasing pyrolysis temperature and heating rate.     

Copyrolysis of scrap tires with waste lubricant oil

Two different types of scrap tires, passenger car tire (PCT) and truck tire (TT) with waste lubricant oil (WLO) were copyrolyzed in a fixed bed reactor at the temperatures of 550, 650 and 800 °C under nitrogen atmosphere. Copyrolysis products were investigated comparatively. The gaseous products were analyzed by GC–TCD. The physical and chemical properties of copyrolysis oils were characterized by means of ASTM methods, GC–FID, GC–MS, and ¹H NMR. In addition, boiling point distributions of hydrocarbons in copyrolysis oils were determined by using simulated distillation curves in comparison with commercial diesel. An increase in the temperature had no effect on the product distributions of copyrolysis and the composition of copyrolysis oils. However, the types of scrap tires strongly effected the product distributions and compositions of copyrolysis oils. Copyrolysis of PCT/WLO produced less amount of liquid and more amount of solid residue than that of copyrolysis of TT/WLO. However, the naphtha and aromatic content in oils from copyrolysis of PCT/WLO was found more than that of TT/WLO. The amount of aromatic content in copyrolysis oils found to be less than that of scrap tire derived oils. By comparing the copyrolysis oils with commercial diesel, copyrolysis oils contained lighter fraction than that of commercial diesel whereas the specific gravities and viscosities of copyrolysis oils were higher than that of commercial diesel.     

Copyrolysis of scrap tires with waste lubricant oil

Two different types of scrap tires, passenger car tire (PCT) and truck tire (TT) with waste lubricant oil (WLO) were copyrolyzed in a fixed bed reactor at the temperatures of 550, 650 and 800 °C under nitrogen atmosphere. Copyrolysis products were investigated comparatively. The gaseous products were analyzed by GC–TCD. The physical and chemical properties of copyrolysis oils were characterized by means of ASTM methods, GC–FID, GC–MS, and ¹H NMR. In addition, boiling point distributions of hydrocarbons in copyrolysis oils were determined by using simulated distillation curves in comparison with commercial diesel. An increase in the temperature had no effect on the product distributions of copyrolysis and the composition of copyrolysis oils. However, the types of scrap tires strongly effected the product distributions and compositions of copyrolysis oils. Copyrolysis of PCT/WLO produced less amount of liquid and more amount of solid residue than that of copyrolysis of TT/WLO. However, the naphtha and aromatic content in oils from copyrolysis of PCT/WLO was found more than that of TT/WLO. The amount of aromatic content in copyrolysis oils found to be less than that of scrap tire derived oils. By comparing the copyrolysis oils with commercial diesel, copyrolysis oils contained lighter fraction than that of commercial diesel whereas the specific gravities and viscosities of copyrolysis oils were higher than that of commercial diesel.     

Comparative investigations of coal pyrolysis under inert gas and H2 at low and high heating rates and pressures up to 10 MPa

Five German hard coals of 6–36 wt% volatile matter yield (maf) were pyrolysed at pressures up to 10 MPa, using two different apparatuses, which mainly differ in the heating rates. One consists of a thermobalance where a coal sample of ≈ 1.5 g is heated at a rate of 3 K min ^?1 under a gas flow of 3 I min^?1. The other apparatus is constructed for rapid heating (10²?10³ K s^?1) of a small sample of ≈10 mg of finely-ground coal distributed as a layer between the folded halfs of a stainless-steel screen, heated by an electric current. The product gas composition was determined by quantitatively analysing for H₂, CH₄, C₂H₄, C₂H₆, CO, CO₂ and H₂O. The amounts of tar and char were measured by weighing. The heating rate, pressure and gas atmosphere were varied. Under an inert gas atmosphere, high heating rates result in slightly higher yields of liquid products, e.g. tar. The yields of light hydrocarbon gases remain the same. With increasing pressure, the thermal cracking of tar is intensified resulting in high yields of char and light hydrocarbon gases. Under H₂, pyrolysis is influenced strongly at elevated pressure. Additional amounts of highly aromatic products are released by hydrogenation of the coal itself, particularly between 500 and 700°C. This reaction is less effective at higher heating rates because of the shorter residence time and diffusion problems of H₂. The yield of light gaseous compounds CH₄ and C₂H₆ increases markedly under either heating condition owing to gasification of the reactive char.     

Activated carbon from solid wastes using a pilot-scale batch flaming pyrolyser

Activated carbon has been prepared from solid wastes carbonised in a pilot-scale batch flaming pyrolyser. Wood furniture waste (chipboard and plywood), scrap tyres, urban sewage, and straw were selected as pollutant solid wastes for this study. Burn-off levels, porosity, and BET surface were determined. From furniture waste derived char, a highly microporous solid was obtained at 850°C with a BET surface area of 855 m²/g. A medium surface area (431 m²/g) activated solid was obtained from tyre derived char at 1000°C. An FT-IR spectroscopic study of activated tyre and furniture derived chars showed different chemical structures and a higher water adsorption capacity for furniture derived solids than for those derived from tyres. The low cost flaming pyrolyser can produce, at pilot scale, chars suitable for activation from furniture wastes and tyres.     

Active carbon from scrap tyres

The possibility of producing active carbon by activation at 850 °C of the char obtained from the pyrolysis (at 450 and 600 °C) of scrap tyres has been studied. The activated char showed good adsorbing characteristics, similar to those of typical commercial grades. The yield and the desired adsorbing capacity depend on the activation time. However, the ash content and friability are quite high; therefore the activated char is suitable for applications in powder form in which the ash does not cause problems.     

Recycling polymeric wastes by means of pyrolysis

Different polymeric wastes, which include materials from the automobile industry, such as tyres, automobile shredder residues (ASR) and sheet moulding compound (SMC), and materials from municipal solid wastes (MSW), such as cardboard, tetrabrik and plastics (LDPE, PP, PS, PET and PVC), pure and mixed, have been pyrolysed in a 3.5 dm³ autoclave at 500 °C for 30 min in a nitrogen atmosphere. The amount and characteristics of the solid, liquids and gases obtained are presented. The suitability of the different materials for the pyrolysis recycling process is discussed. It is concluded that pyrolysis is a very promising technique for recycling tyres, SMC, one type of ASR (heavy ASR), and LDPE, PP and PS, either pure or mixed; with all of them valuable solid, liquid and gaseous products are obtained in pyrolysis. On the contrary, light ASR, tetrabrik and cardboard do not yield valuable products in the pyrolysis process and therefore their recycling by pyrolysis is not of interest, except as a way of volume reduction. PET and PVC turned out to be troublesome in the pyrolysis experiments; for a proper study of their recycling by pyrolysis other operating conditions and installations are required. © 2002 Society of Chemical Industry     

煤焦氧化对其结构和气化行为的影响

采用固定床反应器对煤焦进行部分氧化处理,然后测定氧化后煤焦在水蒸气和CO2中的气化行为,并用SEM,XRD和N2/CO2吸附对煤焦结构进行表征.结果表明,煤焦低温氧化处理可以显著改善煤焦的孔隙结构,大幅增加比表面积,降低煤焦的有序化和石墨化程度,从而提高其气化活性;并且随氧化程度( burnout)增加,煤焦气化活性不断增加.随氧化温度升高(＞600℃),氧化过程逐渐过渡到扩散控制,O2主要在煤焦外表面反应,因而氧化几乎不会改变煤焦的结构,表面积略有增加,对其后续气化活性无明显影响.     

Thermogravimetric study of the devolatilization of hydropyrolysis chars

The devolatilization of hydropyrolysis (HyPy) chars formed at 485–850 °C under 3 MPa and chars formed at 580 °C under 0–5 MPa of H₂ and 3 MPa He is investigated in a thermobalance coupled to two gas chromatographs. The H₂, CH₄ and CO₂ released are analysed every 4 min and all are analysed at the end of the experiment. The amount of residual volatile matter in the chars decreases rectilinearly with the HyPy temperature, whereas their decrease is asymptotic with the HyPy pressure. The char formed under He contains 45% more residual volatile matter than that formed in the same conditions under H₂. The HyPy temperature must be limited if the char is to be burned in a boiler. The CH₄ formation is strongly dependant of the HyPy temperature.     

碱金属Na对黑液水煤浆焦-CO2气化特性的影响

黑液中富含大量的碱金属Na及其化合物,这些碱金属将在黑液水煤浆焦气化过程中起到催化气化的作用.为了研究黑液水煤浆焦-CO2催化气化反应特性,采用XRD、SEM和热重分析技术对黑液水煤浆焦和普通水煤浆焦CO2催化气化实验进行分析,得到了焦炭表面孔隙分布情况、煤浆焦样和气化后残渣XRD分析结果,以及等温条件下气化反应时碳转化率数据.试验结果表明:黑液水煤浆焦表面密集分布很多"斑点"和微孔,说明碱金属Na盐在焦碳表面形成了活化中心点,它们在气化过程中起到催化作用;碱金属Na使焦样表面具有更强的反应位,削弱C-C键的强度,使气化反应更容易进行;同时由于碱金属催化剂在高温气化时将与煤中矿物质反应生成惰性物质,从而可能削弱催化效果.从黑液水煤浆与普通水煤浆XRD晶相分析中可以看出碱金属Na盐主要以氯化钠、硅酸钠形式存在,气化反应后生成的晶相组成主要是霞石和微斜长石.     

Catalytic Vicinal Diacylation of Epoxidized Triglycerides in Canola Oil

The epoxy ring opening and vicinal diacylation of fatty acids in vegetable oils was found to be promising reaction to synthesize stable biolubricants and bioplasticizers. The current research investigation is emphasized on the synthesis of a value added product vicinally diacylated canola oil by sulfated‐ZrO₂. The two‐step research approach employed includes: (i) epoxidation, and (ii) epoxy ring opening and vicinal diacylation of epoxidized triglycerides in the canola oil. Sulfated‐ZrO₂ was prepared and characterized to measure the physico‐chemical properties required for the effective catalysis. The Taguchi (L16 orthogonal array) statistical design method was employed to optimize the process conditions for the maximum formation of diacylated canola oil. Sulfated‐ZrO₂ demonstrated promising activity for the epoxy ring opening and vicinal diacylation of canola oil, and 99 % conversion was achieved at the optimum process conditions of temperature 130 °C, epoxy to acetic anhydride molar ratio (1:1.25), 16 wt% of catalyst loading and reaction time of 1 h which were inferred from the Taguchi analyses. The products were characterized and confirmed with FT‐IR, ¹H NMR and sodium spray mass spectroscopy. Spectroscopic analysis also confirmed the absence of intermediate products. The statistical analyses was undertaken to determine the order, rank and interactions among the process variables. The reaction followed Langmuir–Hinshelwood–Hougen–Watson type mechanism and the kinetic data was fitted in overall second order equation. Calculated apparent activation energy was 23.1 kcal/mol.     

Synthetic fuel production from tea waste: Characterisation of bio-oil and bio-char

The pyrolysis of tea waste was studied for determining the main characteristics and quantities of liquid and solid products. Particular investigated process variables were temperature (673-973 K), heating rate (5-700 K min⁻¹) and nitrogen gas flow rate (200-800 cm³ min⁻¹). The maximum oil and char yields are 30.4 (773 K) and 43.3% (673 K), respectively. The liquid and its aliphatic sub-fraction were characterized by elemental analysis, FT-IR, ¹H NMR, and GC/MS. The char was characterized with elemental analysis, SEM, BET, and FT-IR techniques. The aliphatic sub-fraction of the obtained bio-oil contains predominantly n-alkanes and alkenes, and branched hydrocarbons. According to the experimental results the liquid products can be used as liquid fuels, whereas the solid product seems to be not suitable for adsorption purposes, due to having low surface areas.     

The characteristics of steam gasification of biomass and waste filter carbon

The carbon in a waste filter for water purification may be a new source of energy. The char of waste filter carbon and the char of wood chip have been gasified with steam in a thermobalance reactor under atmospheric pressure. The effect of gasification temperature (700-850°C) and partial pressure of steam (0.3-0.9 atm) on the gasification rate has been investigated. Several gas-solid reaction models have been compared for their prediction ability of the gasification reaction behavior. The modified volumetric reaction model was used to evaluate kinetic data. The gasification rate of waste filter carbon has been compared with the rates of coal and wood chip biomass. The activation energies of filter carbon and wood chip were determined to be 89.1 and 171.4 kJ/mol, respectively. The apparent reaction rate equation for waste filter carbon has been presented.     

Coal devolatilization and char conversion under suspension fired conditions in O2/N2 and O2/CO2 atmospheres

The aim of the present investigation is to examine differences between O₂/N₂ and O₂/CO₂ atmospheres during devolatilization and char conversion of a bituminous coal at conditions covering temperatures between 1173 K and 1673 K and inlet oxygen concentrations between 5 and 28 vol.%. The experiments have been carried out in an electrically heated entrained flow reactor that is designed to simulate the conditions in a suspension fired boiler. Coal devolatilized in N₂ and CO₂ atmospheres provided similar results regarding char morphology, char N₂-BET surface area and volatile yield. This strongly indicates that a shift from air to oxy-fuel combustion does not influence the devolatilization process significantly. Char combustion experiments yielded similar char conversion profiles when N₂ was replaced with CO₂ under conditions where combustion was primarily controlled by chemical kinetics. When char was burned at 1573 K and 1673 K a faster conversion was found in N₂ suggesting that the lower molecular diffusion coefficient of O₂ in CO₂ lowers the char conversion rate when external mass transfer influences combustion. The reaction of char with CO₂ was not observed to have an influence on char conversion rates at the applied experimental conditions.     

The CO2-gasification and kinetics of Shenmu maceral chars with and without catalyst

The CO₂ gasification of maceral chars was performed using CAHN TG-151 pressurized thermobalance under different conditions. The effect of mineral in macerals and catalyst on the gasification reactivity of maceral chars and the gasification kinetics were systematically investigated. The results showed that the apparent gasification rate of maceral chars depends on the temperature, pressure, BET surface area of chars and the gasification extent. With increasing temperature and pressure, the gasification rate of maceral chars all increase. After demineralization, the gasification reactivity of maceral chars all decrease. The gasification reactivity of maceral chars greatly increases with loading catalyst. And the loading method of catalyst has great effect on the gasification reactivity. The maceral chars loaded with catalyst by ultrasonic treatment have higher gasification reactivity than that by impregnation. The comparison of gasification reactivity of maceral charas demineralized maceral chars and maceral chars with and without catalyst showed that vitrinite chars always have higher gasification reactivity than inertinite chars. The kinetic results by distributed activation energy model showed that inertinite char has higher activation energy than vitrinite char, and the addition of catalyst greatly minimizes the activation energy and enhances the gasification rate.