The co-pyrolysis of flame retarded high impact polystyrene and polyolefins

The co-pyrolysis of brominated high impact polystyrene (Br-HIPS) with polyolefins using a fixed bed reactor has been investigated, in particular, the effect that different types of brominated aryl compounds and antimony trioxide have on the pyrolysis products. The pyrolysis products were analysed using FT-IR, GC–FID, GC–MS, and GC–ECD. Liquid chromatography was used to separate the oils/waxes so that a more detailed analysis of the aliphatic, aromatic, and polar fractions could be carried out. It was found that interaction occurs between Br-HIPS and polyolefins during co-pyrolysis and that the presence of antimony trioxide influences the pyrolysis mass balance. Analysis of the Br-HIPS + polyolefin co-pyrolysis products showed that the presence of polyolefins led to an increase in the concentration of alkyl and vinyl mono-substituted benzene rings in the pyrolysis oil/wax resulting from Br-HIPS pyrolysis. The presence of Br-HIPS also had an impact on the oil/wax products of polyolefin pyrolysis, particularly on the polyethylene oil/wax composition which converted from being a mixture of 1-alkenes and n-alkanes to mostly n-alkanes. Antimony trioxide had very little impact on the polyolefin wax/oil composition but it did suppress the formation of styrene and alpha-methyl styrene and increase the formation of ethylbenzene and cumene during the pyrolysis of the Br-HIPS.     

Study of products yield of bagasse and sawdust via slow pyrolysis and iron-catalyze

In this paper, the via slow pyrolysis behavior of the bagasse and sawdust were studied at the different heating rates, the different iron-containing blend pyrolysis and the treatment temperature, the further understood for the pyrolysis of agricultural residues. The distribution of the products yield of the slow pyrolysis process, it is typically performed at temperature between 200 and 600 °C, the pyrolysis temperature increased, the bio-liquids and gas yields tended to increase, which at 400 °C was able to achieve maximum bio-liquids yields, the biochar yields tended to downward. For different heating rate, in the heating rate ranges for 80–100 W, the bio-liquids products yield curve increased from 44.5 wt% to 46.5 wt% for bagasse; the sawdust products yield increased from 41 wt% to 42.75 wt%. Iron-catalysts blend pyrolysis (0, 10, 25, 40 and 50 wt%), the bagasse bio-liquid yields respectively 56.25 wt% in the presence 50% iron-catalysts blend pyrolysis; the sawdust bio-liquid yields respectively 52.5 wt% in the presence 40% iron-catalysts blend. The pyrolysis process were calculated according to the kinetic mechanism were examined, the pyrolysis activation energy was between 6.55 and 7.49 kcal/mol for bagasse. Sawdust the pyrolysis activation energy was between 11.52 and 11.76 kcal/mol. Therefore, in this study a pyrolysis model of bagasse and sawdust thermal treatment may provide both agricultural and forestry transformation importance of resources.     

Measurement and calculation of phase equilibria in the system n-pentane + poly(dimethylsiloxane) at 308.15–423.15 K

Vapor–liquid phase equilibria in the binary system n-pentane+poly(dimethylsiloxane) (PDMS) have been investigated experimentally at temperatures ranging from 308.15 to 423.15 K. The experiments have been performed at pentane mass fractions in the liquid phase ranging from 0 to 80% using the static method. PDMS with average molecular weights of 26 500 g/mol and 103 000 g/mol has been used. The data are in good agreement with several literature data by other researchers, mostly obtained by the use of inverse gas chromatography. The experimental data could be correlated well using the Flory–Huggins activity coefficient model for the polymer phase and the Peng–Robinson equation of state for the gas phase. Using statistical associating fluid theory (SAFT), it was only possible to reproduce the experimentally determined equilibria after adjusting the pure-component parameters of the polymer to the binary equilibria.Further, experimental data have been obtained for the R22 (difluorochloromethane)+PDMS system at 298.15 and 343.15 K.     

Catalytic pyrolysis of Phragmites (reed): Investigation of its potential as a biomass feedstock

In this paper, thermogravimetry, TG, and pyrolysis are used for the thermochemical evaluation of the common reed (Pragmites australis) as a candidate biomass feedstock. The TG analysis indicated that the material loses 4% of its weight below 150 °C through dehydration. The main decomposition reaction occurs between 200 and 390 °C. The rate of weight loss, represented by the derivative thermogravimetric, DTG, signal indicated a multi-step reaction. Kinetic analysis helped in the resolution of the temperature ranges of the overlapping steps. The first step corresponds to the degradation of the hemi-cellulosic fraction and the second to the cellulosic fraction degradation. The TG and DTG signals of reed samples treated with increasing concentration of potassium carbonate (0.6–10 wt%) indicated a catalytic effect of the salt on reed decomposition. The temperature of maximum weight loss rate, DTGmax, exponentially decreased with increasing catalyst content, whilst the initial temperature of the decomposition decreased linearly. The pyrolysis studies were carried out in a Pyrex vertical reactor with sintered glass disc to hold the sample and to aid the fluidization with the nitrogen stream flowing upwards. The reactor was connected to a cyclone and condenser and a gas sampling device. Tar and char are collected and weighed. The gas chromatographic analysis of the evolved gases demonstrated the effect of pyrolysis temperature (400, 450, and 500 °C) on their composition. The temperature increase favors the yields of hydrocarbons, carbon monoxide and hydrogen at the expense of methanol and carbon dioxide. Similarly, reed samples treated with K2CO3 at 10 wt% were pyrolyzed and analyzed. Comparisons for the various parameters (yields, gas composition and carbon–hydrogen recovery) between the untreated and catalyzed reed conversion were also made.     

The effect of storage duration on bio-oil properties

Bio-oil produced by fluidized fast pyrolysis of yellow poplar wood (Liriodendron tulipifera) was stored in sealed glass bottles at 23 °C for 2, 4, 6, 8, or 10 weeks to investigate the effect of storage time on bio-oil properties. Bio-oil viscosity increased with increasing storage duration, while pH, water content and heating value remained unchanged. Thirty-three components were identified in the bio-oils and were classified into five sub-groups: aldehydes and ketones from carbohydrates, aliphatic phenols, phenolic aldehydes, and phenolic ketones from lignin. The concentrations of the sub-groups, especially the carbohydrate-derived ketones and lignin-derived compounds, gradually decreased with prolonged storage. In contrast, the yield of pyrolytic lignin extracted from bio-oils increased with storage duration from 13.2 wt% (fresh bio-oil; control) to 24.3 wt% (10 weeks). The average molecular weight of pyrolytic lignin also increased from 872 (control) to 1161 g mol⁻¹ (10 weeks). The amounts of phenolic hydroxyl and methoxyl groups decreased from 11.2 wt% (control) to 8.0 wt% (10 weeks) and 11.9 wt% (control) to 8.6 wt% (10 weeks), respectively. The observations strongly indicate that the low molecular weight components could participate in the re-polymerization with pyrolytic lignin, and the plausible polymerization reactions could be predicted to esterification, oxidation, hemiacetal/acetal formation and olefinic condensation.     

Catalytic effects of copper(II) chloride and aluminum chloride on the pyrolytic behavior of cellulose

The cellulose without and with catalyst (CuCl₂, AlCl₃) was subjected to pyrolysis at temperatures from 350 to 500 °C with different heating rate (10 °C/min, 100 °C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 37–84 wt% depending on the temperature, the heating rate and the amount of metal chloride. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil. The mixing cellulose with both metal chlorides results with a significant decrease of the liquid product. The non-catalytic pyrolysis of cellulose gives the highest mass yield of levoglucosan (up to 11.69 wt%). The great influence of metal chloride amount on the distribution of bio-oil components was observed. The copper(II) chloride and aluminum chloride addition to cellulose clearly promotes the formation of levoglucosenone (up to 3.61 wt%), 1,4:3,6-dianhydro-α-d-glucopyranose (up to 3.37 wt%) and unidentified dianhydrosugar (MW = 144; up to 1.64 wt%). Additionally, several other compounds have been identified but in minor quantities. Based on the results of the GC–MS, the effect of pyrolysis process conditions on the productivity of selected chemicals was discussed. These results allowed to create a general model of reactions during the catalytic pyrolysis of cellulose in the presence of copper(II) chloride and aluminum chloride.     

Characterization of the different fractions obtained from the pyrolysis of rope industry waste

A study of the possibilities of pyrolysis for recovering wastes of the rope's industry has been carried out. The pyrolysis of this lignocellulosic residue started at 250 °C, with the main region of decomposition occurring at temperatures between 300 and 350 °C. As the reaction temperature increased, the yields of pyrolyzed gas and oil increased, yielding 22 wt.% of a carbonaceous residue, 50 wt.% tars and a gas fraction at 800 °C. The chemical composition and textural characterization of the chars obtained at various temperatures confirmed that even if most decomposition occurs at 400 °C, there are some pyrolytic reactions still going on above 550 °C. The different pyrolysis fractions were analyzed by GC–MS; the produced oil was rich in hydrocarbons and alcohols. On the other hand, the gas fraction is mainly composed of CO₂, CO and CH₄. Finally, the carbonaceous solid residue (char) displayed porous features, with a more developed porous structure as the pyrolysis temperature increased.     

Composition of the liquid product by pyrolysis of dried distiller's grains with solubles

Presently, dried distiller's grains with solubles (DDGS) are mainly used as the livestock feed. However, the high fiber content in DDGS limits its use as the diet for animals. Therefore, with increasing production of DDGS in recent years, it is desirable to find some new uses of DDGS for fuels and/or for high value chemicals. In this paper, experiments on pyrolysis of DDGS by spouted-entrained bed and by fixed bed are carried out, and the pyrolytic liquids are analyzed by GC/MS. It was found that the composition of the liquid by pyrolysis of DDGS in 490–570 °C by spouted-entrained bed is rather complex, and varies with pyrolytic temperature. However, the pyrolysis of DDGS material is not quite suitable to the process by spouted-entrained bed, due to a severe clogging problem inside the reactor. By fixed bed, the composition of the oil phase of the liquid obtained in 490–610 °C is much simpler, mainly phenol derivatives, fatty acids and their esters. When pyrolyzed at 570 °C with catalyst of CaO, aliphatic and aromatic hydrocarbons are generated more, while fatty acids and their esters are much reduced.     

Kinetic study of low-temperature conversion of plastic mixtures to value added products

Batch-mode pyrolysis of 200.0 g samples of polymers was studied at low temperature. The cracking reaction was carried out in a stainless-steel autoclave with reaction temperatures of 360, 380, 400 and 420 °C, initial pressure of 6.325 kPa (absolute pressure) and reaction times of 0–240 min. Based on the experimental results, a four-lump kinetic model has been developed to describe the production distribution of the light fractions, middle distillates and heavy fraction. This model reasonably fitted the results in each reaction of operation conditions. It was also found that the pyrolysis kinetics of separated plastic, mixed plastic and mixed plastic containing additives can be described by the same kinetic model. The plastic additives have not had a great influence on the product distribution and kinetics of the mixed plastic pyrolysis. Finally, the optimum conditions of low-temperature conversion of plastic mixtures to value-added products were established. The formation of heavy fractions from HDPE was as high as 70 wt% at 380 °C at a reaction time of 250 min. During the thermal degradation of plastic mixtures, the heavy fractions yielded up 50 wt% for 30 min reaction time at 400 °C. The total activation energies for the conversion of HDPE and the plastic mixtures were estimated to be 217.66 kJ mol⁻¹ and 178.49 kJ mol⁻¹, respectively.     

Conversion of the Estonian fossil and renewable feedstocks in the medium of supercritical water

Two different Estonian oil shales, peat, and willow biomass were submitted to supercritical water conversion at unified operating conditions. The yield and chemical composition of conversion products were investigated by chromatographic, FTIR-spectroscopic and ultimate analysis techniques. The results reveal significant difference in products yield and composition those depending on the feedstock origin and its chemical composition. Common and specific features in conversion of fossil and renewable matter were described. The maximum and the minimum oil yield per organic matter, 62.7 and 18.6%, respectively, were obtained in conversion of oil shales. Willow biomass conversion resulted in the highest yield of gas and water (50%). The solubility of oils despite original feedstock increases with solvents used in the raw: dimethyl ketone < water < benzene. The investigation on group composition of the benzene-soluble compounds demonstrated that various oxygen compounds dominate over hydrocarbons in all cases. The majority of hydrocarbons was represented by polycyclic aromatic ones. Aliphatic hydrocarbons, making 6–11% of the benzene-soluble oil were represented by n-alkanes up to C₃₃. Conversion gases, especially those of peat and willow were characterized by high carbon dioxide content. Supercritical water conversion can be used as an alternative method for the liquefaction and gasification of different feedstocks.     

Phase equilibria study of the (N-octylisoquinolinium thiocyanate ionic liquid + aliphatic and aromatic hydrocarbon,or thiophene) binary systems

Binary liquid + liquid phase equilibria for 8 systems containing N-octylisoquinolinium thiocyanate, [C₈iQuin][SCN] and aliphatic hydrocarbon (n-hexane, n-heptane), cyclohexane, aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene) and thiophene have been determined using dynamic method. The experiment was carried out from room temperature to the boiling-point of the solvent at atmospheric pressure. For the tested binary systems the mutual immiscibility with an upper critical solution temperature (UCST) for {IL + aliphatic hydrocarbon, or thiophene} were observed. The immiscibility gap with lower critical solution temperature (LCST) for the {IL + aromatic hydrocarbon} were determined. The parameters of the LLE correlation equation for the tested binary systems have been derived using NRTL equation. The phase equilibria diagrams presented in this paper are compared with literature data for the corresponding ionic liquids with N-alkylisoquinolinium, or N-alkylquinolinium cation and with thiocyanate – based ionic liquids. The influence of the ionic liquid structure on mutual solubility with aliphatic and aromatic hydrocarbons and thiophene is discussed.     

Feedstock recycling of synthetic and natural rubber by pyrolysis in a fluidized bed

An indirect heated fluidized bed process has been used for the pyrolysis of synthetic and natural rubber. The throughput capacity for the continuously running plant was 500–3000 g/h. The results are compared to a pilot plant for the pyrolysis of whole tires. Beside the recovery of oil and carbon black it was another goal of the study to investigate how much monomer material such as isoprene and isobutene can be obtained from synthetic and natural rubber. The pyrolysis parameters were optimized such as pyrolysis temperature, kind of fluidizing gas, and residence time of the gas in the pyrolysis reactor. Main products of the pyrolysis of tires are an aromatic-rich oil and carbon black, which can be reused. While it was possible to obtain only 2–4 wt% of isobutene, the isoprene content reached 22 wt% from natural rubber.     

Pyrolysis of waste tyres: The influence of USY catalyst/tyre ratio on products

In this paper, an ultrastable Y-type (USY) zeolite was investigated with two-staged pyrolysis–catalysis of waste tyres. Waste tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a secondary catalytic reactor. The main objective of this paper was to obtain high concentration of certain aromatic hydrocarbons suitable to be used as a chemical feedstock rather than a liquid fuel, and the influence of catalyst/tyre ratio on the product yield and composition of derived oils. The light fraction (boiling point < 220 °C) was distilled from the derived oil prior to be analyzed with gas chromatography/mass spectrometry (GC/MS). It showed that the increase of catalyst/tyre ratio resulted in high yield of gas at the expense of the oil yield. The high catalyst/tyre ratio favored to increase the concentration of light fraction (<220 °C) in oil. Increasing the catalyst/tyre ratio resulted in significant changed in the concentration of benzene, toluene, xylenes and the alkyl aromatic compounds. For benzene and toluene, the highest concentration was obtained at the catalyst/tyre ratio of 0.5. The concentration of xylenes increased with the increasing of catalyst/tyre ratio.     

Conventional and microwave induced pyrolysis of coffee hulls for the production of a hydrogen rich fuel gas

This paper describes the conventional and microwave-assisted pyrolysis of coffee hulls at 500, 800 and 1000 °C. The influence of the pyrolysis method and temperature on the product yields and on the characteristics of the pyrolysis products is discussed. It was found that the pyrolysis of this particular residue gives rise to a larger yield of the gas fraction compared to the other fractions, even at relatively low temperatures. A comparison of microwave-assisted pyrolysis and conventional pyrolysis showed that microwave treatment produces more gas and less oil than conventional pyrolysis. In addition, the gas from the microwave has much higher H₂ and syngas (H₂ + CO) contents (up to 40 and 72 vol.%, respectively) than those obtained by conventional pyrolysis (up to 30 and 53 vol.%, respectively), in an electric furnace, at similar temperatures. From the pyrolysis fraction yields and their higher heating values it was found that the energy distribution in the pyrolysis products decreases as follows: gas > solid > oil. Moreover, the energy accumulated in the gas increases with the pyrolysis temperature. By contrast, the energy accumulated in the char decreases with the temperature. This effect is enhanced when microwave pyrolysis is used.     

Isobaric (vapour + liquid) equilibria of binary systems containing butyl acetate for the separation of methoxy aromatic compounds (anisole and guaiacol) from biomass fast pyrolysis oil

Developing value-added chemicals from pyrolysis oil has been gaining increasing attention. Thus effective separation and purification of the pyrolysis oil are important and the phase equilibrium data are essential for the design and simulation of the processes. In this study, isobaric vapour–liquid equilibrium (VLE) for the two binary mixtures (butyl acetate + anisole) and (butyl acetate + guaiacol) have been determined at 101.33 kPa, a knowledge of which is essential for the separation of methoxy aromatic compounds (anisole and guaiacol) from biomass fast pyrolysis oil using butyl acetate as a solvent. All the experimental values were confirmed to be thermodynamically consistent using the van Ness method. The NRTL, UNIQUAC, and Wilson activity coefficient models were applied to regress the experimental values. The calculated results agreed well with the measured values. Furthermore, the results were calculated by the UNIFAC (Do) method (modified UNIFAC model) in which aromatic methoxyl is treated as a group (ACOCH₃). The new interaction parameter (ACOCH₃–CH₃COO) was obtained and proved to be reliable. Based on the preceding results, a feasible separation process for the ternary mixture (butyl acetate + anisole + guaiacol) has been designed to obtain the required products.     

Bio-oil from fast pyrolysis of rice husk: Yields and related properties and improvement of the pyrolysis system

Rice husk was fast pyrolysed at temperatures between 420 °C and 540 °C in a fluidized bed, and the main product of bio-oil is obtained. The experimental result shows that the highest bio-oil yield of 56 wt% was obtained at 465 °C for rice husk. Chemical composition of bio-oil acquired was analyzed by GC–MS and its heat value, stability, miscibility and corrosion characteristics were determined. These results showed that bio-oil obtained can be directly used as a fuel oil for combustion in a boiler or a furnace without any upgrading. Alternatively, the fuel can be refined to be used by vehicles. Furthermore, the energy performance of the pyrolysis process was analyzed.     

Pyrolysis oil from fast pyrolysis of maize stalk

Maize stalk was fast pyrolysed at temperatures between 420 °C and 580 °C in a fluidized-bed, and the main product of pyrolysis oil was obtained. The experimental results showed that the highest pyrolysis oil yield of 66 wt.% was obtained at 500 °C for maize stalk. Chemical composition of the pyrolysis oil acquired was analyzed by GC–MS and its heat value, stability, miscibility and corrosion characteristics were determined. These results showed that the pyrolysis oil could be directly used as a fuel oil for combustion in a boiler or a furnace without any upgrading. Alternatively, the fuel could be refined to be used by vehicles.     

Asymmetric addition of diethylzinc to aldehydes catalyzed by a camphor-derived β-amino alcohol

The asymmetric addition of diethylzinc to aromatic and aliphatic aldehydes, including linear aliphatic ones, catalyzed by 2 mol % of β-amino alcohol (1S, 2R)-7,7-dimethyl-1-morpholin-4-yl-bicyclo[2.2.1]heptan-2-ol 10 gave the corresponding secondary alcohols in high yields and with up to 94% ee at ambient temperature after 15 min.     

(Liquid + liquid) equilibria in the binary systems (aliphatic,or aromatic hydrocarbons + 1-ethyl-3-methylimidazolium ethylsulfate,or 1-butyl-3-methylimidazolium methylsulfate ionic liquids)

(Liquid + liquid) equilibria of 14 binary systems composed of n-hexane, n-heptane, benzene, toluene, o-xylene, m-xylene, or p-xylene and 1-ethyl-3-methylimidazolium ethylsulfate, [emim]EtSO₄, or 1-butyl-3-methylimidazolium methylsulfate, [bmim]MeSO₄, ionic liquids have been done in the temperature range from (293.2 to 333.2) K. The solubility of aliphatic is less than those of the aromatic hydrocarbons. In particular, the solubility of hydrocarbons in both ionic liquids increases with the temperature in the order n-heptane < n-hexane < m-xylene < p-xylene < o-xylene < toluene < benzene. Considering the high solubility of aromatics and the low solubility of aliphatic hydrocarbons as well as totally immiscibility of the ionic liquids in all hydrocarbons, these new green solvents may be used as potentials extracting solvents for the separation of aromatic and aliphatic hydrocarbons.     

Sub-critical water extraction of bitumen from Huadian oil shale lumps

Three sizes of Huadian oil shale lumps from 1 cm to 10 cm were extracted by sub-critical water at 350 °C and 16 MPa for 2–70 h. The oil shale lumps were fractured alone the shale texture in sub-critical water that greatly improved the extraction efficiency of bitumen from the large- and middle-sized sample. The extract yields of bitumen from different sized samples were similar when the extraction time is longer than 20 h and stabilized at about 18 wt.% (ad) after 50 h duration. With the increase of extraction time, asphaltene and preasphaltene extracts were gradually decomposed to maltene. The gas chromatography–mass spectrometry (GC–MS) analysis of the extracts showed that n-alkanes, n-alk-1-enes, isoprenoids, n-alk-2-ones and n-alkanoic acids were the major components. In contrast, aromatic extracts were rare and most of them were remained in the shale residue. The pyrolysis gas chromatography–mass spectrometry (Py-GC–MS) analysis of the spent shale showed that the final undecomposed organics in kerogen were some macromolecular linear hydrocarbon, n-alk-2-ones and n-alkanoic acids fragments. The comparison of the classical pyrolyzate and the sub-critical water extracts showed that the water extracts contained more long-chain alkanes than anhydrous pyrolysis and the alkene extracts could transform to alkanes in sub-critical water. Moreover, the n-alkanoic acids could be decomposed to short-chain compounds through the cleavage of carbon carbon bonds.