废轮胎热解炭黑与工业炭黑的粒径及化学组成

用激光粒度分析仪测定了废轮胎热解炭黑的粒径分布,用扫描电子显微镜、X-射线衍射法及X-射线光电子能谱法分析了热解炭黑和工业炭黑的形态、表面化学组成以及表面碳元素的结合状况。结果表明,热解炭黑的粒径分布是添加在轮胎中各种型号工业炭黑粒径分布的叠加。热解炭黑表面形态和组成接近于工业炭黑N660;热解炭黑的表面附着更多的有机物以及ZnO、ZnS等无机物,且随着热解温度的升高,附着的有机物含量减小,无机物中ZnO含量减小,ZnS含量增多。     

ESCA characterization of commercial carbon blacks and of carbon blacks from vacuum pyrolysis of used tires

Pyrolytic carbon blacks (CB_p) were obtained by vacuum pyrolysis of used tires in a batch reactor at a total pressure ranging from 0.3 to 20.0 kPa, and temperatures ranging from 420 to 700°C. CB_p differ from commercial carbon blacks used initially in the tire fabrication. A series of commercial carbon blacks with different surface areas and structures and CB_p obtained under different pyrolysis conditions were characterized using ESCA and SEM techniques to investigate the effect of the pyrolysis conditions on the chemical nature of the surface of CB_p.     

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.     

Acid-base method for the demineralization of pyrolytic carbon black

The carbon black material used as reinforcing filler in tires was recovered by vacuum pyrolysis at a temperature of 500°C and a total pressure of 20 kPa. The pyrolytic carbon black obtained (CBp) was contamined by various additives of the original tire. Contaminants were also produced by chemical reactions occurring in the pyrolysis reactor. The contamination is reflected by the high content of ash and gritty materials (coke) present in the CBp. A characterization of the recovered carbon black was performed and a possible reduction of the ash content by sulfuric acid and sodium hydroxide treatment was investigated. The variables which were studied included the ratio of reactant to carbon black, the reactant concentration, the treatment temperature and the reaction time. Properties of the commercial carbon black filler grade N539 were compared to those of the CBp recovered before and after the demineralization treatment.     

废轮胎回转窑中试热解炭中碳元素化学形态

应用X射线光电子能谱（XPS）对废轮胎回转窑中试热解炭（PCB）中C元素的化学形态进行分析.荷电效应及背景校正后,分别应用“非对称性Gaussian-Lorentzian线性和函数”与“Gaussian函数”对非对称与对称峰进行拟合.结果发现,热解温度≥500 ℃时,热解充分,热解炭本体中C元素的化学形态类似商用炭黑（CCB）N660,而热解炭表面吸附沉积物中C元素的化学形态不同于本体,随热解温度升高,表面吸附物中类石墨质C有所增加;450℃时,热解不充分,热解炭本体中类石墨质C含量少,表面吸附物少;热解炭按粒径存在一定的分布,热解炭颗粒越小,石墨质C含量越低;热解炭表面吸附、沉积物厚度的近似数量级为0.2 mm,热解炭本体中C元素的化学形态并未受到表面吸附、沉积层太大的影响.     

Pyrolysis of scrap tyres

Cross-section samples (2–3 cm wide), representative of a whole car tyre, have been pyrolysed under nitrogen in a 3.5 dm³ autoclave at 300°C, 400°C, 500°C, 600°C and 700°C. The whole solid, liquid and gaseous products generated during each pyrolysis were collected and characterised. No significant influence of temperature on the amount and characteristics of pyrolysis products was observed over 500°C. Tyre-pyrolysis liquids are a complex mixture of C₅–C₂₀ organic compounds, with a great proportion of aromatics. They have high gross calorific values, GCV (∼42 MJ kg⁻¹) and N and S contents (0.4% and 1.2%, respectively) within those specified for certain heating fuels. About 30 wt.% of such liquids is an easily distillable fraction with boiling points (70–210°C) in the range of commercial petrol, and about 60 wt.% of them have the boiling point range (150–370°C) typical of diesel oil. Pyrolysis gases are composed of hydrocarbons of which C₁ and C₄ are predominant, together with some CO, CO₂ and SH₂; they have very high gross calorific values (68–84 MJ m⁻³). Tyre-pyrolysis residues have equal dimensions as the original tyre portion and are easily disintegrable into black powder and steel cords. The black powder has surface areas comparable to those of commercial carbon blacks, but it has a great proportion of ash and impurities (∼12 wt.%), which are the inorganic fillers added to tyre rubber; it may have a potential use as semireinforcing or nonreinforcing carbon black.     

Catalytic pyrolysis of tyres: influence of catalyst temperature

Two stage pyrolysis–catalysis of used tyres was undertaken to upgrade the derived oil to a highly aromatic oil suitable to be used as a chemical feedstock rather than a liquid fuel. The tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a secondary fixed bed reactor containing zeolite catalyst. The pyrolysis reactor was maintained at 500 °C and the influence of catalyst temperature between 430 and 600 °C on the yield and composition of the derived oils was examined. Two zeolite catalysts were examined; a Y-type zeolite catalyst and zeolite ZSM-5 catalyst of differing pore size and surface activity. The influence of the catalyst was to reduce the yield of oil with a consequent increase in the gas yield and formation of coke on the catalyst. Single ring aromatic hydrocarbons, benzene, toluene and xylenes present in the oils showed a marked increase in the presence of the catalyst. Naphthalene and alkylated naphthalenes were also analysed and showed a similar marked increase in the concentration when a catalyst was present. The Y-type zeolite catalyst of larger pore size and higher surface activity was found to produce higher concentrations of aromatic compounds compared to the ZSM-5 catalyst. Increasing the catalyst temperature resulted in significant changes in the concentration of benzene, toluene, xylenes, naphthalene and the alkylated naphthalenes.     

Pyrolytic carbon: factors controlling in-rubber performance

Abstract

Pyrolysis of waste tyres not only tackles the environmental issues associated with disposal, but also enables the recovery of valuable products such as oils and carbon fillers for elastomeric materials. This study was instigated to benchmark the in-rubber properties of pyrolytic carbon (often referred to as pyrolysis carbon black, pCB) and to understand the compositional parameters that dictate performance. Colloidal properties suggest the pCB materials to have a reinforcing potential between that of N330 and N550 carbon blacks, whereas physical property data suggest that they are more akin to the N700 series. Fundamentally, this disparity in performance appears to be the result of carbonaceous residues on the pCB surface, which both reduce surface activity and dispersability of the recyclate. Both thermogravimetric and dynamic mechanical analyses confirmed a number of pCB samples to have the same specific surface activity, regardless of the pyrolysis process or feedstock utilised.     

THERMAL REGENERATION OF ACTIVATED CARBONS

The thermal regeneration of activated carbons loaded with p-nitrophenol (PNP) and other aromatic compounds was studied using a thermal balance. After pyrolysis of the adsorbates in nitrogen at 700°C, the residues were gasified with oxygen at 415 to 500°C or with steam at 840 to 920°C. Residues from PNP were several times more reactive to oxygen than the base carbons and also showed greater chemisorption of oxygen. For steam gasification, only small differences between spent and fresh carbons were found.     

Structure and performance of soy hull carbon adsorbents as affected by pyrolysis temperature

Soy hulls were evaluated as a source of adsorbent carbon for vegetable oil processing. Soy hull carbon was prepared by burning ground soy hulls (<100 mesh) at 300, 400, 500, or 700°C in a muffle furnace. The structure of the soy hull carbon was studied by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Crude soy oil was processed with the soy hull carbon products at 2% (w/w) in the laboratory under commercial bleaching conditions. Free fatty acids (FFA), peroxide value, phospholipid phosphorus (PLP), and lutein content of the treated samples were determined. SEM of the samples revealed particle size ranging from 1 to 2 mm. Increasing the pyrolysis temperature resulted in expansion and disruption of cellular structure. FTIR spectra of the carbon samples showed major differences in peak intensities at 3600 to 3200, 1600, and 1450 cm⁻¹ due to pyrolysis temperature. XRD revealed a predominantly amorphous structure with increasing pyrolysis temperature, which also resulted in an increased alkaline surface. Soy hull carbon decreased the FFA content of oil samples compared to that of crude oil, with the exception of carbon that was prepared at 300°C (P<0.05). A similar trend was observed in the adsorption of peroxides; however, no trends were observed in the adsorption of PLP or lutein. Higher pyrolysis temperature decreased randomness of the carbon and imparted a certain degree of structural order. This may be beneficial in providing physical access of the adsorbate molecule to the adsorbent surface.     

Identification of the surface characteristics of carbon blacks by pyrolysis GC-MASS

Subtle differences in surface characteristics on carbon blacks are investigated by using Curie-point Pyrolysis Gas Chromatography Mass Spectrometry (CP-PGC-MASS). The PGC-MASS diagrams of carbon blacks are assigned as the fingerprints for distinguishing differences in surface properties. For carbon black-N220 pyrolyzed below 445°C, only one aromatic ring hydrocarbons are found in PGC-MS diagrams, whereas, when pyrolyzation temperatures exceed 445°C, two ring aromatic hydrocarbons are also found. Toluene Sohxlet extraction of the carbon blacks will not cause a significant change of surface properties, however toluene will remain as a contaminant on the surface even for those samples dried for 24 h at 200°C before PGC-MASS measurements. A new surface structure model of carbon black is proposed based on the PGC-MASS results.     

Preparation of Pyrolytic Carbon Black from Scrap Tire Rubber Crumb and Evaluation in New Rubber Compounds

Summary: Pyrolytic carbon black (CBp) has been prepared by rubber crumb pyrolysis under nitrogen flow at 700 °C. The CBp obtained by this process had an average surface area of 81 m² · g^?1 and was obtained in 43% yield over the starting rubber crumb. Although the CBp surface area can be increased up to 109 m² · g^?1 by washing away the Zn‐ and Si‐based ashes with HF treatment, the CBp was tested in a standard NR/SBR‐based formulation without any purification and ash extraction. CBp was tested at increasing loading levels as partial or full replacement of a standard N339 furnace carbon black. CBp depresses the physical properties of the rubber compound in a way which is directly proportional to the amount added. The reason of this result and the limited reinforcing effect is discussed in terms of low surface area and low structure in comparison to N339 carbon black as well as in terms of low surface activity, the interference of the ashes and the poor dispersion. Ideas of further development works are outlined.

     

Fluorination of carbon blacks: an X-ray photoelectron spectroscopy study: IV. Reactivity of different carbon blacks in CF4 radiofrequency plasma

The effect of CF₄-plasma enhanced fluorination on the surface modification of carbon blacks has been examined using XPS. Three different types of carbon blacks have been studied: a thermal black, a furnace black and a high electrical conducting black. The analysis of the XPS spectra of fluorinated carbon black samples indicates that all fluorine atoms, fixed at the surface and in a subsuperficial zone of the particles, are covalently linked to carbon atoms. The influence of the physicochemical properties and morphology of these three types of carbon blacks on the fluorination reaction has also been investigated. The proportion of different types of fluorinated carbon atoms, i.e. on one hand CF_x surface and border groups of graphitic bulk domains for which the planar configuration of the graphene layers is preserved together with the sp² character of C, i.e. structures of type I, on the other hand polyalicyclic perfluorinated structures in which sp³C form puckered layers similar to those of covalent fluorographites, i.e. structures of type II, and also the F/C ratio of the fluorinated groups are related to the surface morphology and depend on the microstructural organization of particles. When the microstructure ordering and graphitic character of the carbon increase, the size of the ordered graphitic domain also increases. At the same time the density, the size of defects and proportion of protonated sp³C entities bridging the graphene layers decrease. As a consequence, the proportion of carbon atoms, potentially able to form perfluorinated CF₂ and CF₃ groups, decreases. The relative contribution of those groups is appreciably higher in fluorinated compounds which are derived from carbon blacks with a lower structural order.     

Nickel cuprate supported on cordierite as an active catalyst for CO oxidation by O2

The physicochemical, surface and catalytic properties of 10 and 20 wt% CuO, NiO or (CuO–NiO) supported on cordierite (commercial grade) calcined at 350–700 °C were investigated using XRD, EDX, nitrogen adsorption at −196 °C and CO oxidation by O₂ at 220–280 °C. The results obtained revealed that the employed cordierite preheated at 350–700 °C was well-crystallized magnesium aluminum silicate (Mg₂Al₄Si₅O₁₈). Loading of 20 wt% CuO or NiO on the cordierite surface followed by calcination at 350 °C led to dissolution of a limited amount of both CuO and NiO in the cordierite lattice. The portions of CuO and NiO dissolved increased upon increasing the calcination temperature. Treating a cordierite sample with 20 wt% (CuO–NiO) followed by heating at 350 °C led to solid–solid interaction between some of the oxides present yielding nickel cuprate. The formation of NiCuO₂ was stimulated by increasing the calcination temperature above 350 °C. However, raising the temperature up to ≥550 °C led to distortion of cuprate phase. The chemical affinity towards the formation of NiCuO₂ acted as a driving force for migration of some of copper and nickel oxides from the bulk of the solid towards their surface by heating at 500–700 °C. The S_BET of cordierite increased several times by treating with small amounts of NiO, CuO or their binary mixtures. The increase was, however, less pronounced upon treating the cordierite support with CuO–NiO. The catalytic activity of the cordierite increased progressively by increasing the amount of oxide(s) added. The mixed oxides system supported on cordierite and calcined at 450–700 °C exhibited the highest catalytic activity due to formation of the nickel cuprate phase. However, the catalytic activity of the mixed oxides system reached a maximum limit upon heating at 500 °C then decreased upon heating at temperature above this limit due to the deformation of the nickel cuprate phase.     

Effects of carbon blacks on electrical properties of EPDM compounds

The correlations between mechanical and electrical properties of ethylene propylene diene terpolymer (EPDM) compounds and carbon black types and levels applied are studied. Tensile strength increases with an increase of the carbon black, especially for carbon black with higher surface area. Tracking resistance of EPDM compounds improves when a small amount of relatively nonconductive carbon blacks are added to EPDM compounds, whereas conductive carbon blacks decrease both dielectric properties and tracking resistance of EPDM compounds. Possible reasons for these results are discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2540–2546, 2000     

Catalytic characteristics of various rubber-reinforcing carbon blacks in decomposition of methane for hydrogen production

Carbon black has recently been reported to act as an effective catalyst for methane decomposition and to exhibit stable catalytic behavior despite carbon deposition, and thus it can be used for CO₂-free production of hydrogen from natural gas. In this work, various carbon blacks with different primary particle size were investigated with respect to methane decomposition under atmospheric pressure from 1123 to 1223 K. Catalytic characteristics, such as activity, activation energy and reaction order, were investigated and compared. It was observed that with decreasing primary particle size (or increasing specific surface area), the specific activity increased and the activation energy decreased. The reaction orders for various pelletized, rubber-reinforcing carbon blacks were 0.6–0.7, about the same regardless of the primary particle size, while they were near 1 for fluffy carbon blacks. Fluffy carbon black showed higher activity and activation energy than the pelletized carbon black of the same primary particle size. Changes of the surface morphology during carbon deposition were observed by TEM. Variations of the number of active sites were discussed in regard of the primary particle size, carbon deposition and binder. The presence of different types of active sites was also suggested.     

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.     

废旧轮胎裂解炭黑的改性及其应用进展

废旧轮胎作为对环境有害的固体废弃物，其组成包括炭黑、白炭黑和胶粉等多种有价值的资源。在现有回收技术中，废轮胎热裂解技术可有效回收裂解油、炭黑和钢丝等，在国内获得了广泛应用。相对于已经普遍利用的热解油和钢丝来说，热解炭黑含有质量分数14-21%的灰分和胶质层，它的高价值利用是实现废旧轮胎循环回用的关键。很多研究者开展了热解炭黑不同的改性处理工艺研究，改性后的热解炭黑可被应用于多个领域。该文主要概括了热解改性炭黑在橡胶生产中的补强作用、改性活性炭吸附剂、电池材料、以及沥青和油墨填料等方面的应用，综述了上述应用领域内热解炭黑的处理和改性方法，并指出今后热解炭黑高价值回用的方向和改性方法。     

Preparation and characterization of superhydrophobic conductive fluorinated carbon blacks

Superhydrophobic conductive carbon blacks were prepared by covalent bonding of perfluorocarbon and perfluoropolyether chains on the conductive carbon black surface. Perfluorodiacyl and perfluoropolyether peroxides were used as reagents for the chemical treatment. Their thermal decomposition produced respectively, perfluoroalkyl and perfluoropolyether radicals that directly bonded the polycyclic aromatic structure of carbon black surface. Measurements of contact angles with water on molded pellets made with carbon black powder demonstrated that water droplets were enduringly stable on the treated carbon blacks. Contact angle values were significantly high, exceeding the superhydrophobicity threshold. On the contrary, the droplets were adsorbed in few seconds by the native carbon black. Conductivity measurements showed that the covalent linkage of fluorinated chains weakly modified the electrical properties of the conductive carbon black, even if the surface properties changed so deeply. The relationship between the linkage of fluorinated chains and the variations of physical–chemical properties were studied combining electron spectroscopy, resistivity measurements, X-ray diffraction, scanning electron microscopy, surface area analysis and thermal gravimetric analysis. The superhydrophobic conductive carbon blacks were compared with a superhydrophobic carbon black obtained by direct fluorination of conductive carbon black with elemental fluorine, F₂.     

Chemical transformations during pyrolysis of Rundle oil shale

Rundle shale (Queensland, Australia) was pyrolysed at 12.5 K min⁻¹ to 350–500 °C for 10–240 min. The structures of the liquid products and pyrolysis residues were investigated by a number of n.m.r. spectroscopic techniques including cross-polarization and dipolar dephasing. N.m.r. provided a simple method for detecting nitrile carbon and measuring terminal and internal olefinic hydrogen in shale oil. It was found that the ratio of terminal olefinic hydrogen to internal olefinic hydrogen in shale oil increases by a factor of three over the range 350–500 °C. Moreover, the results suggest that aromatic rings in Rundle shale residues are not highly substituted and hence that aromatic ring condensation reactions are not important during pyrolysis. From elemental, yield and n.m.r. data, the conversion of aliphatic carbon to aromatic carbon during pyrolysis was found to be as high as 25% at 500 °C.