Understanding the influence of microwave on the relative volatility used in the pyrolysis of Indonesia oil sands

In this paper, pyrolysis of Indonesian oil sands(IOS) was investigated by two different heating methods to develop a better understanding of the microwave-assisted pyrolysis. Thermogravimetric analysis was conducted to study the thermal decomposition behaviors of IOS, showing that 550 °C might be the pyrolysis final temperature. A explanation of the heat–mass transfer process was presented to demonstrate the influence of microwave-assisted pyrolysis on the liquid product distribution. The heat–mass transfer model was also useful to explain the increase of liquid product yield and heavy component content at the same heating rate by two different heating methods. Experiments were carried out using a fixed bed reactor with and without the microwave irradiation. The results showed that liquid product yield was increased during microwave induced pyrolysis,while the formation of gas and solid residue was reduced in comparison with the conventional pyrolysis. Moreover, the liquid product characterization by elemental analysis and GC–MS indicated the significant effect on the liquid chemical composition by microwave irradiation. High polarity substances(ε N 10 at 25 °C), such as oxyorganics were increased, while relatively low polarity substances(ε b 2 at 25 °C), such as aliphatic hydrocarbons were decreased, suggesting that microwave enhanced the relative volatility of high polarity substances. The yield improvement and compositional variations in the liquid product promoted by the microwave-assisted pyrolysis deserve the further exploitation in the future.     

Pyrolysis and thermo‐oxidative degradation of polycyclopentadiene

Thermal degradation of polycyclopentadiene polymer (PCPD) was investigated by pyrolysis gas chromatography (PGC) in the temperature range of 500–950°C. The nature and composition of the pyrolyzates at various temperatures are presented, and the mechanism of degradation is explained. The activation energy of decomposition (E_a) was obtained from an Arrhenius‐type plot using the concentration of the product ethylene (C₂) at different pyrolysis temperatures and the value was found to be 138 kJ mol⁻¹. Thermo‐oxidative degradation of PCPD in the presence of ammonium perchlorate (AP), the most commonly used oxidizer for polymeric fuel binders, was studied at a pyrolysis temperature of 700°C. The compositions of the products with varying amounts of AP are given, and the exothermicity of oxidative decomposition reactions is evaluated. The energetics of the degradation processes are compared with those of polybutadiene type polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 635–641, 2000     

New method for evaluation of kinetic parameters and mechanism of degradation from pyrolysis–GC studies: Thermal degradation of polydimethylsiloxanes

Thermal degradation of polydimethylsiloxane (PDMS) polymers having hydroxyl (PS) and vinyl (PS‐V) terminals was studied by pyrolysis‐gas chromatography (PGC) in the temperature range from 550 to 950°C. The degradation products were primarily cyclic oligomers ranging from trimer (D₃) to cyclomer D₁₁ and minor amounts of linear products and methane. The product composition varied significantly with pyrolysis temperature and extent of degradation. A new method was developed to derive a mass loss‐temperature curve (pyrothermogram, PTG) and to determine the kinetic parameters of decomposition (k, n, and E_a) from sequential pyrolysis studies. It was shown that isothermal rate constants can be derived from repeated pyrolysis data. Good agreement between the rate constants derived from the two methods validates the methodology adopted. This was further confirmed from thermogravimetric studies. The E_a values for the decomposition of PS and PS‐V derived from sequential pyrolysis were 40 ± 2 and 46 ± 2 kcal mol⁻¹, respectively. Various mechanisms for the degradation of PDMS were reviewed and discussed in relation to the PGC results. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 441–450, 1999     

Polysiloxane‐Derived Ceramics Containing Nanowires with Catalytically Active Tips

By direct foaming of a Pt‐containing polysiloxane precursor, macroporous ceramics were generated by pyrolysis at 1400°C under nitrogen or argon. The growth of nanowires was induced via a vapor–liquid–solid mechanism in which the Pt particles acted as deposition site for the decomposition gases released upon pyrolyzing the preceramic polymer. SEM, HR‐SEM, TEM/EDX, and XRD investigations revealed that pyrolysis under argon atmosphere leads to short SiC nanowires of only a few micrometers length and under nitrogen atmosphere Si₃N₄ nanowires evolved, with length of several 10 μm. In both cases the tips of the nanowires mainly consisted of PtSi. In contrast to samples pyrolyzed at 600°C, the components after higher temperature pyrolysis showed moderate‐specific surface areas of 55–67 m²/g. In CO oxidation experiments, a good catalytic activity was found for the Pt silicide particles, suggesting that despite their relatively large size, their location at the tips of the nanowires affords them good reactivity.     

Thermal degradation of EVA and EBA—A comparison. I. Volatile decomposition products

This is the first in a series of papers in which structural changes during thermal degradation of ethylene-vinyl acetate (EVA) and ethylene-butyl acrylate (EBA) copolymers are compared. EVA, containing 11.4 mol% vinyl acetate (VA) and EBA, containing 5.4 mol% butyl acrylate (BA), were pyrolyzed at 280°C in nitrogen for 30 min. In another series of pyrolysis, EVA containing 1.2, 2.2, and 11.4 mol% VA were treated at 150–190°C for 3 h. The volatile decomposition products were collected in cooled traps respectively gas bags and then analysed with GC-MS and ion-chromatography. EVA is rather labile. The main volatile decomposition product is acetic acid. A linear decomposition rate was found already at the lowest investigated pyrolysis temperature, 150°C. After 30 min at 280°C every 15th of the acetate side groups had been eliminated. EBA is much more stable to pyrolysis. Thirty minutes at 280°C resulted in a decomposition of one out of 1500 BA groups. Butene is the main volatile decomposition product. Ester pyrolysis is supposed to account for the degradation of both types of polymers. The big difference in reactivity is presumably due to conformational differences. The ester pyrolysis mechanism will result in random unsaturations in EVA and carboxylic groups in EBA. To a minor extent acetaldehyde is formed when EVA is degraded. According to the mechanisms suggested, carbonyl groups remain in the main chain. Contrary to what is reported for poly(butyl acrylate), no alcohol was formed when pyrolysing EBA. This indicates that adjacent acrylate groups are needed for alcohol formation. For both types of polymer, scissions of the main chain results in hydrocarbon fragments mainly. In addition, acrylate containing fragments are observed when EBA is degraded. EVA, however, does not give any acetate-containing fragments.     

Thermal degradation mechanism of poly(ether imide) by stepwise Py–GC/MS

The thermal degradation of poly(ether imide) (PEI) was studied through a combination of thermogravimetric analysis and stepwise pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) techniques with consecutive heating of the samples at fixed temperature intervals to achieve narrow temperature pyrolysis conditions. The individual mass chromatograms of various pyrolysates were correlated with pyrolysis temperatures to determine the pyrolysis mechanism. The major mechanisms were two‐stage pyrolysis, involving main‐chain random scission, and carbonization. In the first stage, the scission of hydrolyzed imide groups, ether groups, and isopropylidene groups produced CO+CO₂ and phenol as the major products and was accompanied by chain transfer of carbonization to form partially carbonized solid residue. In the second pyrolysis stage, the decomposition of the partially carbonized solid residue and remaining imide groups formed CO+CO₂ as the major product along with benzene and a small amount of benzonitrile. The yield of CO+CO₂ was the largest fraction in the total ion chromatogram of the evolved gas mixtures. Hence, the thermal stability of the imide group was identical to the maximum thermogravimetry loss rates in the two‐stage pyrolysis regions. Afterward, carbonization dominated the decomposition of the solid residue at high temperatures. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1151–1161, 2001     

High-resolution thermogravimetry of liquid crystalline copoly(p-oxybenzoate–ethylene terephthalate–m-oxybenzoate)

Thermotropic liquid crystalline terpolymers consisting of three units of p-oxybenzoate (B), ethylene terephthalate (E), and m-oxybenzoate (M), were investigated through high-resolution thermogravimetry to evaluate their stability and kinetic parameters of thermal degradation in nitrogen and air. Overall activation energy data of the first major decomposition was calculated through three calculating methods. Thermal degradation occurs in three major steps in both nitrogen and air. Three kinds of degradation temperatures (T_d, T_m1, T_m2) are slightly higher and the first maximum weight-loss rates are slightly lower in nitrogen than in air, suggesting a higher thermostability in nitrogen. The thermal degradation temperatures range from 450 to 457°C in nitrogen and 441 to 447°C in air and increase with increasing B-unit content at a fixed M-unit content of 5 mol %. The temperatures at the first maximum weight loss rate range from 452 to 466°C in nitrogen and 444 to 449°C in air and increase slightly with an increase in B-unit content. The first and second maximum weight-loss rates are maintained at almost 9.2–10.8 and 4.0–6.1%/min in nitrogen (11.2–12.0 and 3.9–4.2%/min in air) and vary slightly with copolymer composition. The residues after the first major step of degradation are predicted on the basis of the complete exclusion of ester and ethylene groups and hydrogen atoms and compared with those observed experimentally. The char yields at 500°C in both nitrogen and air are larger than 42.6 wt % and increase with increasing B-unit content. However, the char yields at 800°C in nitrogen and air are different. The activation energy and ln(pre-exponential factor) for the first major decomposition are slightly higher in nitrogen than in air and increase with an increase in B-unit content at a given M-unit content of 5 mol %. There is no regular variation in the decomposition order with the variation of copolymer composition and testing atmosphere. The activation energy, decomposition order, and ln(pre-exponential factor) of the thermal degradation for the terpolymers are located in the ranges of 212–263 kJ mol⁻¹, 2.4–3.5, 33–41 min⁻¹, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2911–2919, 1999     

Structure–property relationship in copolymers of methacrylic acid esters. I. Thermal behavior

This article describes the synthesis and thermal characterization of copolymers of methyl methacrylate (MMA) and alkyl methacrylates. The copolymerization was carried out using different mol fractions (0.05–0.25) of alkyl methacrylates, i.e., octyl methacrylate (OMA)/decyl methacrylate (DMA)/lauryl methacrylate (LMA)/stearyl methacrylate (SMA), in the initial feed at 80°C. The copolymer composition was determined from ¹H-NMR. The thermal stability of the copolymers was investigated by thermogravimetric analysis and pyrolysis gas chromatography. A two/three-step degradation was observed in the copolymer samples. The monomers were the major product of degradation in most of the copolymers except in SMA/MMA copolymers where the product of side-group elimination was also observed. An attempt was also made to determine the yield of the monomers during degradation and then to evaluate the copolymer composition. © 1994 John Wiley & Sons, Inc.     

Über die Thermische Umsetzung von Mono-n-alkylbenzenen

Thermal Reaction of Mono-n-alkyl-benzenes The pyrolysis of ethyl-( 1 ), n-propyl-( 2 ), n-hexyl-( 3 ) and n-octylbenzene ( 4 ) has been studied under conditions of steam cracking (600 to 800°C) in a laboratory scale tubular reactor. The overall activation energies determined for ( 1 ) to ( 4 ) were found to be nearly identical (221 to 227 kJ · mol⁻¹) obviously caused by similar initial steps. The main liquid product observed was styren accompanied by ω-phenyl-1-alkenes and α-olefins. Benzene is an important side product of 1 . It might be formed mainly by a hydrogen assisted dealkylation via a cyclohexadienyl type radical as reactive intermediate.     

Zur Pyrolyse von 3-Ethylpent-2-en – Ein weiterer Hinweis auf eine Homoallyl-Umlagerung

Pyrolysis of 3-Ethylpent-2-ene — a Further Evidence for a Homoallylic-Rearrangement The pyrolysis of 3-ethylpent-2-ene has been studied under conditions of steam cracking in the temperature range 600—700°C in a laboratory scale tubular reactor. The main products of decomposition were methane, 2-ethylbutadiene and isoprene. The majority of products obviously arose from H abstraction and radical addition, typical for radical chain reactions in olefins decomposition including phenomena resulting from allylic resonance. The formation of isoprene, however, could only be explained by a reaction network including a homoallylic rearrangement.     

Bio-oil from olive oil industry wastes: Pyrolysis of olive residue under different conditions

Olive residues were pyrolysed in a fixed bed reactor under different pyrolysis conditions to determine the role of final temperature, sweeping gas flow rate and steam velocity on the product yields and liquid product composition with a heating rate of 7 °C/min. Final temperature range studied was between 400 and 700 °C and the highest liquid product yield was obtained at 500 °C. Liquid product yield increased significantly under nitrogen and steam atmospheres. Liquid products obtained under the most suitable conditions were characterised by elemental analyses, FT-IR and ¹H-NMR. In addition, column chromatography was employed and the yields of the sub-fractions were calculated. Gas chromatography was achieved on n-pentane fractions. The results show that it is possible to obtain liquid products similar to petroleum from olive residue if the pyrolysis conditions are chosen accordingly.     

Bio-oil from olive oil industry wastes: Pyrolysis of olive residue under different conditions

Olive residues were pyrolysed in a fixed bed reactor under different pyrolysis conditions to determine the role of final temperature, sweeping gas flow rate and steam velocity on the product yields and liquid product composition with a heating rate of 7 °C/min. Final temperature range studied was between 400 and 700 °C and the highest liquid product yield was obtained at 500 °C. Liquid product yield increased significantly under nitrogen and steam atmospheres. Liquid products obtained under the most suitable conditions were characterised by elemental analyses, FT-IR and ¹H-NMR. In addition, column chromatography was employed and the yields of the sub-fractions were calculated. Gas chromatography was achieved on n-pentane fractions. The results show that it is possible to obtain liquid products similar to petroleum from olive residue if the pyrolysis conditions are chosen accordingly.     

Thermal decomposition mechanisms of bis(2-fluoro-2,2-dinitroethyl) formal (FEFO) and bis(2-fluoro-2,2-dinitroethyl) difluoroformal (DFF) from simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) measurements

The simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) technique has been applied to measure the vapor pressures and evaluate the thermal decomposition chemistry of two energetic liquids, bis(2-fluoro-2,2-dinitroethyl)formal (FEFO) and bis(2-fluoro-2,2-dinitroethyl)difluoroformal (DFF). The resulting heat of vaporization (ΔH_vap) and vapor pressure at 25°C are 20.3 ± 0.2 kcal/mol and 0.4 ± 0.1 millitorr for FEFO, and 17.3 ± 0.2 kcal/mol and 5.1 ± 1.1 millitorr for DFF. The thermal decomposition of FEFO indicates there are six major pyrolysis pathways. The results suggest that FEFO initially decomposes at 150°C by rearrangement of the nitro group ( NO₂) to the nitrite group ( O NO), followed by loss of NO. Some NO₂ is also formed at 170°C. Between 200°C–300°C, further pyrolysis occurs. In one pathway, the FEFO backbone remains intact and a high molecular-weight product is formed. The other three pathways involve scission of the FEFO backbone; one yielding CO₂ (possibly N₂O), one yielding CH₂O and CO, and one yielding C₃H₂NOF. Differences in the thermal decomposition behaviors in the liquid and gas phases are observed. In the thermal decomposition of DFF, the formal fluorine atoms stabilize the backbone structure. Numerous minor thermal decomposition products are also reported.     

Energetics and Structure of Polymer‐Derived Si–(B–)O–C Glasses: Effect of the Boron Content and Pyrolysis Temperature

The structure and properties of polymer‐derived Si–(B–)O–C glasses have been shown to be significantly influenced by the boron content and pyrolysis temperature. This work determined the impact of these two parameters on the thermodynamic stability of these glasses. High‐temperature oxide melt solution calorimetry was performed on a series of amorphous samples, with varying boron contents (0–7.7 at.%), obtained by pyrolysis of precursors made by a sol–gel technique. Thermodynamic analysis of the calorimetric results demonstrated that at a constant pyrolysis temperature, adding boron makes the materials energetically less stable. While the B‐containing glasses pyrolyzed at 1000°C were energetically less stable than the competitive crystalline components, increasing the pyrolysis temperature to 1200°C led to their enthalpic stability. ²⁹Si and ¹¹B MAS nuclear magnetic resonance (NMR) spectroscopy measurements on selected samples confirmed a decrease in the concentrations of mixed Si‐centered SO_iC_4?i and B‐centered BO_jC_3?j bonds at the expense of formation of SiO₄ and B(OSi)₃ species (indicating a tendency toward phase separation) when the boron content and pyrolysis temperature increased. In light of the findings from calorimetry and NMR spectroscopy, we propose a structure–energetic relationship in Si–(B–)O–C glasses.     

Kinetics of the pyrolysis of cellulose in the temperature range 250–300°C.

Samples of α-cellulose, containing 0.11–0.14% ash, were isothermally pyrolyzed in a fluidized bath in a nitrogen environment at 250–298°C. Results were reported in terms of volatilization (based on weight-loss measurements) and decomposition (in term of glucosan loss). The findings show three distinct stages of pyrolysis: (1) an initial period of rapid decomposition and weight loss; (2) a range in which both the volatilization and decomposition are of zero order; (3) a region in which the volatilization follows a first-order rate, leaving a char deposit which does not undergo further pyrolysis. The degree of decomposition and volatilization occurring during the zero-order phase increases with increasing temperature. A single activation energy of 42 kcal./mole describes both the decomposition and volatilization rates in the zero-order phase over the entire 250–298°C. range.     

Mathematical modelling of lignin pyrolysis

Seven lignins from different sources were pyrolysed (i) isothermally in vacuum over the temperature range 300–1300 °C and (ii) at a constant heating rate of 30 °C min^?1 and a pressure of 0.1 MPa over the temperature range 150–900 °C. The mass fraction of each product—char, tar and gas species—and the elemental composition of the char and the tar were determined for the flash pyrolysis experiments. The evolution rates of the gas species and the tar versus the dynamic temperature of pyrolysis were determined for the constant heating rate pyrolysis experiments. Although the amount of each product species varied from lignin to lignin, the evolution rates were insensitive to the lignin source and the extraction process. To model the data, modifications were made to a recently developed model of coal pyrolysis. The model proved to be successful in simulating both the data from vacuum flash pyrolysis and constant heating rate pyrolysis of Iotech lignin.     

Low‐Density Open Cellular Silicon Carbide Foams from Sucrose and Silicon Powder

Open cellular SiC foams with low densities were prepared by thermo‐foaming and setting (130°C–150°C) of silicon powder dispersions in molten sucrose followed by pyrolysis and reaction sintering at 1500°C. The bubbles generated in the dispersion by water vapor produced by the –OH condensation was stabilized by the adsorption of silicon particles on the air‐molten sucrose interface. The composition of a sucrose‐silicon powder mixture for producing SiC foam without considerable unreacted carbon was optimized. The sucrose in the thermo‐foamed silicon powder dispersion leaves 24 wt% carbon during the pyrolysis. The sintering additives such as alumina and yttria promoted the silicon‐carbon reaction. SiC nanowires with diameters in the range of 35–55 nm and length >10 μm observed on the cell walls as well as in the fractured strut region were grown by both vapor–liquid–solid and vapor–solid mechanisms. Large SiC foam bodies without crack could be prepared as the total shrinkage during pyrolysis and reaction sintering was only ~30 vol%. The relatively low compressive strength (0.06–0.41 MPa) and Young's modulus (14.9–24.2 MPa) observed was due to the large cell size (1.1–1.6 mm) and high porosity (93%–96%).     

Studies on the development of improved reverse osmosis membranes from cellulose acetate–acetone–formamide casting solutions

Improved membranes from cellulose acetate–acetone–formamide casting solutions have been prepared for low-pressure reverse osmosis applications. The film-casting details for one such type of membranes (Batch 400) are as follows. Casting solution composition: cellulose acetate (E-398-3), 17 wt-%, acetone, 56 wt-%, formamide, 27 wt-%; temperature of casting solution, 24°C; temperature of casting atmosphere, 24°C; casting atmosphere, ambient air in contact with 30 wt-% acetone in aqueous solution; solvent evaporation period, 30 sec; gelation medium, ice-cold water. Using aqueous feed solutions containing 3500 ppm of NaCl, the product rates obtained with the above membranes at 95, 90, and 60% levels of solute separation were 15.9, 22.1, and 58.7 gallons/(day ft²), respectively, at 250 psig under feed flow conditions corresponding to a mass transfer coefficient of 45 × 10^?4 cm/sec on the high-pressure side of the membrane. The effects of casting solution composition, presence of acetone in the casting atmosphere, evaporation period, evaporation rate constant, and the remoteness of casting solution composition from the corresponding phase boundary composition on membrane performance and shrinkage temperature profile were found to be similar to those reported earlier for membranes obtained from cellulose acetate–acetone–aqueous magnesium perchlorate casting solutions. The results illustrate the practical utility of the approach based on the solution structure–evaporation rate concept for creating more productive reverse osmosis membranes.     

Study on characterization of pyrolysis and hydrolysis products of poly(vinyl chloride) waste

Poly(vinyl chloride) PVC pyrolysis and hydrolysis are conducted in a fixed bed reactor and in an autoclave, respectively, under different operating conditions such as the temperature and time. The product distribution is studied. For the PVC pyrolysis process, the main gas product is HCl (55% at 340°C), there is 9% hydrocarbon gas (C₁–C₅), the liquid product fraction is about 5% (at 340°C), and the solid residue fraction is about 31% (at 340°C). For the hydrolysis process, the main gas product is HCl (55.8% at 240°C) and the solid residue is about 49.6% (at 240°C). The pyrolysis liquid product is analyzed by using gas chromatography with magic‐angle spinning. Aromatic hydrocarbons are the main class (90%), of which the major part is benzene (33%). The residue produced through pyrolysis and hydrolysis is investigated by high‐resolution solid‐state ¹³C‐NMR. These details revealed by the high‐field NMR spectra provide importmant information about the chemical changes in the PVC pyrolysis and hydrolysis process. The mechanism of PVC hydrolysis dechlorination is also discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3252–3259, 2003     

Pyrolysis of tetralin

The pyrolysis of tetralin has been studied at 500 °C. The pyrolysis products resulting from the decomposition of 1-¹³C-tetralin were analysed by ¹³C n.m.r. spectroscopy to determine the carbon redistribution in these substances. Some results were confirmed by experiments with ¹⁴C-labelled compounds. Under the conditions employed, carbon scrambling is observed only in the aliphatic portion of the products. The primary mode of decomposition of tetralin proceeds via homolysis of the 1–8a bond. No equilibrium between tetralin and naphthalene plus hydrogen takes place in the absence of a catalyst.