A shock tube study of pyrolysis of tetrahydrothiophene at elevated temperatures

A single pulse shock tube has been used to study the pyrolysis of a hydrogenated sulphur compound, tetrahydrothiophene over the temperature range 1686–1885 K and pressures between 2.4 and 3.5 bars. Product yield and composition was determined using capillary column gas‐chromatography with flame ionization detection and flame photometric sulphur selective detection. The principal hydrocarbon products at all temperatures were C₂H₄ and C₂H₂. Other hydrocarbon reaction products were CH₄, C₂H₆, C₃H₄, C₃H₆, C₄H₃, C₄H₆, C₄H₁₀, C₄H₄, C₆H₆, C₄H₂ and some traces of C₅ and C₆H₅ species. The sulphur compounds identified were hydrogen sulphide, carbon disulphide, thiophene and traces of ethyl mercapton. The pyrolysis experiments indicated that at lower temperatures the hydrogenated thiophene molecule reacts in two unimolecular channels to form C₂H₄+(CH₂)2–S in the major faster channel which may be the route for other products. However, a second lower route may be the formation of C₃H₆+CH₂S. The rate constant obtained for tetrahydrothiophene pyrolysis calculated for this study was k_dis(C4H8S)=1.26×10¹³ exp (316.9 kJ mol^?1) s^?1. Copyright © 2004 John Wiley & Sons, Ltd.     

Dry and steam reforming of biomass pyrolysis gas for rich hydrogen gas

Biomass pyrolysis gas (including H₂, CO, CH₄, CO₂, C₂H₄, C₂H₆ and etc.) reforming for hydrogen production over Ni/Fe/Ce/Al₂O₃ catalysts was presented in this study. This study investigated how the operating conditions, such as the calcinations temperature of catalysts, the reaction temperature, the gas hourly space velocity (GHSV) and the ratio of H₂O/C, affect the conversion of CH₄ and CO₂ and the selectivity of hydrogen from dry and steam reforming of pyrolysis gas. The experimental results indicated that, under the conditions: the reaction temperature of 600 °C, the GHSV of 900 h⁻¹ and H₂O/C of 0.92, the reaction efficiency is the optimal. Especially, the concentration of H₂, CO, CH₄, CO₂, and C₂H_n (C₂H₄ and C₂H₆) were 36.80%, 10.48%, 9.61%, 42.62%, 0.49% respectively. The conversion of CH₄ and CO₂ reached 45.9% and 51.09%, respectively. There were all kinds of reactions during the processing of reforming of pyrolysis gas. And the main reactions changed with the operation condition. It was due to the promoting or inhibiting interaction among different constituents in the pyrolysis gas and the different activity of catalysts in the different operation condition.     

Entrained flow gasification of straw- and wood-derived pyrolysis oil in a pressurized oxygen blown gasifier

Fast pyrolysis oil can be used as a feedstock for syngas production. This approach can have certain advantages over direct biomass gasification. Pilot scale tests were performed to investigate the route from biomass via fast pyrolysis and entrained flow gasification to syngas. Wheat straw and clean pine wood were used as feedstocks; both were converted into homogeneous pyrolysis oils with very similar properties using in-situ water removal. These pyrolysis oils were subsequently gasified in a pressurized, oxygen blown entrained flow gasifier using a thermal load of 0.4 MW. At a pressure of 0.4 MPa and a lambda value of 0.4, temperatures around 1250 °C were obtained. Syngas volume fractions of 46% CO, 30% H₂ and 23% CO₂ were obtained for both pyrolysis oils. 2% of CH₄ remained in the product gas, along with 0.1% of both C₂H₂ and C₂H₄. Minor quantities of H₂S (3 vs. 23) cm³ m⁻³, COS (22 vs. 94) cm³ m⁻³ and benzene (310 vs. 532) cm³ m⁻³ were measured for wood- and straw derived pyrolysis oils respectively. A continuous 2-day gasification run with wood derived pyrolysis oil demonstrated full steady state operation. The experimental results show that pyrolysis oils from different biomass feedstocks can be processed in the same gasifier, and issues with ash composition and melting behaviour of the feedstocks are avoided by applying fast pyrolysis pre-treatment.     

Experimental and kinetic modeling study on methylcyclohexane pyrolysis and combustion

Methylcyclohexane is the simplest alkylated cyclohexane, and has been broadly used as the representative cycloalkane component in fuel surrogates. Understanding its combustion chemistry is crucial for developing kinetic models of larger cycloalkanes and practical fuels. In this work, the synchrotron vacuum ultraviolet photoionization mass spectrometry combined with molecular-beam sampling was used to investigate the species formed during the pyrolysis of methylcyclohexane and in premixed flame of methylcyclohexane. A number of pyrolysis and flame intermediates were identified and quantified, especially including radicals (e.g. CH₃, C₃H₃, C₃H₅ and C₅H₅) and cyclic C6- and C7-intermediates (benzene, 1,3-cyclohexadiene, cyclohexene, toluene, C₇H₁₀ and C₇H₁₂, etc.). In particular, the observation of cyclic C6- and C7-intermediates provides important experimental evidence to clarify the special formation channels of toluene and benzene which were observed with high concentrations in both pyrolysis and flame of methylcyclohexane. Furthermore, the rate constants of H-abstraction of methylcyclohexane via H attack, and the isomerization and decomposition of the formed cyclic C₇H₁₃ radicals were calculated in this work. A kinetic model of methylcyclohexane combustion with 249 species and 1570 reactions was developed including a new sub-mechanism of MCH. The rate of production and sensitivity analysis were carried out to elucidate methylcyclohexane consumption, and toluene and benzene formation under various pyrolytic and flame conditions. Furthermore, the present kinetic model was also validated by experimental data from literatures on speciation in premixed flames, ignition delays and laminar flame speeds.     

Shock-tube pyrolysis of chlorinated hydrocarbons: Formation of soot

Soot formation in pyrolysis of chlorinated methanes, their mixtures with methane, and chlorinated ethylenes were studied behind reflected shock waves by monitoring the attenuation of an HeNe laser beam. An additional single-pulse shock-tube study was conducted for the pyrolysis of methane, methyl chloride, and dichloromethane. The experiments were performed at temperatures 1300–3000K, pressures 0.4–3.6 bar, and total carbon atom concentrations (1–5) × 10¹⁷ atoms/cm³. The amounts of soot produced in the pyrolysis of chlorinated hydrocarbons are larger than that of their nonchlorinated counterparts. The sooting behavior and product distribution can be generally explained in terms of chlorine-catalyzed chemical reaction mechanisms. The pathway to soot from chlorinated methanes and ethylenes with high H : Cl ratio proceeds via the formation of C₂H, C₂H₂, and C₂H₃ species. For chlorinated hydrocarbons with low H : Cl ratio, the formation of C₂ and its contribution to soot formation at high temperatures becomes significant. There is evidence for the importance of CHCl radical and its reactions in the pyrolysis of dichloromethane.     

An experimental study of fuel-rich 1,3-pentadiene and acetylene/propene flames

Fuel-rich laminar premixed flat flames of an acetylene/propene (1:1) mixture and of 1,3-pentadiene were investigated at 50 mbar in order to compare their flame chemistries for identical C/H (0.625) and C/O (0.77) ratios; under these conditions, observed differences in the reaction pathways should be related to fuel structure. Concentrations of the most important species for benzene formation were obtained by molecular beam mass spectrometry (MBMS). Temperature was measured with laser-induced fluorescence (LIF) of seeded NO. The burnt gas temperatures in both flames were similar with maximum values of 2250 K and 2100 K, respectively. The data were analyzed with respect to the formation of C₆ species, in particular to that of benzene as a key species in the soot formation mechanism. As a consequence of different fuel-specific primary decomposition reactions, the two flames show a strikingly different pattern of intermediate compounds, enhancing different possible benzene formation pathways. Relative reaction flows were also calculated from the experimental results which confirm this observation; however, large uncertainties in some important rate coefficients are noted. While the C₃H₃ recombination reaction contributes an important fraction of benzene formed in each flame, the contribution of e.g. C₄H₅ + C₂H₂ cannot be overlooked in the 1,3-pentadiene flame, C₄H₅ being an important pyrolysis product of 1,3-pentadiene. The present results can also be compared to those obtained under similar conditions in pure acetylene and pure propene flames as well as in flames burning further C₅ fuels including 1-pentene and cyclopentene. The consistent data sets provided here as part of this series of systematic investigations should be valuable for testing flame models that include the fuel-rich chemistry of higher hydrocarbons.     

An experimental and theoretical study of toluene pyrolysis with tunable synchrotron VUV photoionization and molecular-beam mass spectrometry

An experimental study of toluene pyrolysis (1.24 vol.% toluene in argon) was performed at low pressure (1.33 kPa) in the temperature range of 1200–1800 K. The pyrolysis process was detected with the tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry (MBMS). Species up to m/z = 202 (C₁₆H₁₀), containing many radicals (CH₃, C₃H₃, C₅H₃, C₅H₅, C₇H₅, C₇H₇, C₉H₇, C₁₁H₇ and C₁₃H₉) and isomers, such as C₃H₄ (propyne and allene), C₄H₄ (vinylacetylene and 1,2,3-butatriene), C₅H₅ (cyclopentadienyl radical and pent-1-en-4-yn-3-yl radical), C₆H₄ (3-hexene-1,5-diyne and benzyne), C₆H₆ (benzene and fulvene), C₇H₈ (toluene and 5-methylene-1,3-cyclohexadiene) and so on, were identified from near-threshold measurements of photoionization mass spectra, and the mole fraction profiles of the pyrolysis products were evaluated from measurements of temperature scan. Experimental results indicate that the reaction C₇H₈ → C₇H₇ and the subsequent reactions are dominant at comparatively low temperature (<1440 K), while the reaction C₇H₈ → C₆H₅ and subsequent reactions gradually become competitive and important with increasing temperature. Furthermore the barriers of the decomposition pathways of toluene and benzyl radical determined by quantum mechanical calculation are in good agreement with the initial formation temperatures of the species. Based on the mole fractions and formation temperatures of the detected pyrolysis species, a simple reaction network is deduced. At relatively high temperatures, H-abstraction is prevalent and the mole fraction of C₂H₂ is so high that many aromatics are formed through the hydrogen-abstraction/C₂H₂-addition (HACA) mechanism. Moreover the reactions of benzyl with toluene/benzyl/phenyl/propargyl radicals to directly produce larger aromatics should play an influential role in PAH formation. Meanwhile the five-member-ring recombination mechanism also plays an indispensable role in the aromatics growth, as cyclopentadienyl radical (C₅H₅) was determined to be a major product of the decomposition of toluene.     

Combined experimental and theoretical study of acetylene semi-hydrogenation over Pd/Al2O3

The semi-hydrogenation of acetylene (C₂H₂ + H₂ = C₂H₄, ΔH = −172 kJ mol⁻¹) is a well-studied reaction that is important for purification of ethylene, C₂H₄, feed used in polyethylene production. Pd-based catalysts are most commonly used to remove acetylene from ethylene feed prior to Ziegler–Natta polymerization because acetylene is a poison for Ziegler–Natta catalysts. New applications of the analogous catalytic processes, with similar requirements for the conversion and selectivity, are considered for the storage of H₂ within the context of the H₂ economy. Here, a combination of experimental and theoretical studies was employed to explore the performance of synthesized Pd nanoparticles and the feasibility of using computational modelling for predicting their catalytic properties. Specifically, a model 5%Pd/Al₂O₃ nanocatalyst was successfully synthesized using high-throughput flame spray pyrolysis (FSP) method. As a catalyst for acetylene semi-hydrogenation, the material shows high conversion of 97%, a modest selectivity of 62%, and a turnover frequency of ethylene formation of 5 s⁻¹. The experimental data were further supported by computational modelling of catalytic properties. Results of microkinetic simulations, based on parameters obtained from DFT calculations, over a Pd₃₀/Al₂O₃(100) model system were correlated with experiments. The insights from this direct comparison of theory and experiments provide indications for future improvements of the theoretical predictions and for novel types of materials with improved catalytic properties.     

Optimization of dilute acid and enzymatic hydrolysis for dark fermentative hydrogen production from the empty fruit bunch of oil palm

Pretreatment of the empty fruit brunch (EFB) from oil palm was investigated for H₂ fermentation. The EFB was hydrolyzed at various temperatures, H₂SO₄ concentrations, and reaction times. Subsequently, the acid-hydrolysate underwent enzymatic saccharification under various temperature, pH, and enzymatic loading conditions. Response surface methodology derived the optimum sugar concentration (SC), hydrogen production rate (HPR), and hydrogen yield (HY) as 28.30 g L⁻¹, 2601.24 mL H₂ L⁻¹d⁻¹, and 275.75 mL H₂ g⁻¹ total sugar (TS), respectively, at 120 °C, 60 min of reaction, and 6 vol% H₂SO₄, with the combined severity factor of 1.75. Enzymatic hydrolysis enhanced the SC, HY, and HPR to 34.52 g L⁻¹, 283.91 mL H₂ g⁻¹ TS, and 3266.86 mL H₂ L⁻¹d⁻¹, respectively, at 45 °C, pH 5.0, and 1.17 mg enzyme mL⁻¹. Dilute acid hydrolysis would be a viable pretreatment for biohydrogen production from EFB. Subsequent enzymatic hydrolysis can be performed if enhanced HPR is required.     

Measurement and modeling of shock-tube ignition delay for propene

Propene ignition was studied behind reflected shock waves at postshock temperatures ranging from 1270 to 1820 K and postshock pressures from 0.95 to 4.7 atm. Reactant concentrations were varied from 0.8 to 3.2% propene and from 3.6 to 15.1% oxygen diluted in argon, giving equivalence ratios ranging from 0.5 to 2.0. The pressure-based ignition delay correlation equation τ(s) = 4.2 × 10⁻¹⁵ [C₃H₆]^0.378[O₂]^−1.043 exp(48800/RT₅) for mol/cm³ and cal units was derived. The data could be accounted for using a reaction mechanism with 463 elementary reactions.     

Experimental and theoretical study on propane pyrolysis to produce gas and soot

The pyrolysis gas and soot production characteristics of propane at different temperatures and residence time were studied experimentally. Based on the combustion mechanism of propane proposed by the University of California, San Diego and Appel mechanism, a new mechanism of propane pyrolysis and soot formation, SD-APP_MECH was established. The reaction paths and dominant controlling reactions of propane pyrolysis and soot production were investigated. According to the experimental results, the new mechanism was optimized to predict the processes of propane pyrolysis and soot formation accurately. The optimized mechanism of propane pyrolysis was named as C₃H₈_MECH. The results showed that propane begins to pyrolyse at around 970 K, the main components of the syngas are H₂, CH₄, C₂H₂ and C₂H₄. At the later stage of pyrolysis, C₂H₂ was generated from C₂H₄ dehydrogenation at 1150 K. When the temperature is below 1173 K, little soot was produced. However, the soot formation rate increased obviously when the temperature is higher than 1250 K. The soot diameter increased with the temperature increasing, and the amount of soot formation decreased with the residence time reducing. The mole fraction of dominant products in propane pyrolysis and soot formation rate calculated from the C₃H₈_MECH mechanism agreed well with the experimental values.     

Synthesis gas production by biomass pyrolysis: Effect of reactor temperature on product distribution

This paper describes mass, C, H, and O balances for wood chips pyrolysis experiments performed in a tubular reactor under conditions of rich H₂ gas production (700–1000 °C) and for determined solid heating rates (20–40 °C s⁻¹). Permanent gases (H₂, CO, CH₄, CO₂, C₂H₄, C₂H₆), water, aromatic tar (10 compounds from benzene to phenanthrene and phenols), and char were considered in the balance calculations. Hydrogen (H) from dry wood is mainly converted into CH₄ (more than 30% mol. of H at 900 °C), H₂ (from 9% to 36% mol. from 700 to 1000 °C), H₂O, and C₂H₄. The molar balances showed that the important yield increase of H₂ from 800 to 1000 °C (0.10 Nm³ kg⁻¹ to 0.24 Nm³ kg⁻¹ d.a.f. wood) cannot be solely explained by the analyzed hydrocarbon compounds conversion (CH₄, C₂, aromatic tar). Possible mechanisms of H₂ production from wood pyrolysis are discussed.     

Thermogravimetric-Mass Spectrometric Study of the Pyrolysis Behavior of Shenmu Macerals Under Hydrogen and Argon

The pyrolysis characteristics of macerals separated from Chinese Shenmu coal were systematically investigated using TG-151 pressurized thermobalance coupling with mass spectrometer under 0.1 MPa of Ar and H₂, heating rate of 10°C/min and final temperature of 900°C. The TG/DTG results showed that vitrinite always had a higher volatile matter yield, larger maximum rate of weight loss, lower temperature of the maximum rate of weight loss than inertinite. Inertinite showed high response to the external hydrogen, especially at a higher temperature. The gases evolved during thermogravimetric analysis of macerals were analyzed on-line by mass spectrometer for the relative intensity of H₂O, C₁–C₄, and C₆H₆. An obvious difference in evolution curves could be observed. The content of all gases evolved from vitrinite was higher than those from inertinite in both atmospheres. The amount of H₂O and light hydrocarbons was higher in H₂ than that in Ar, indicating the hydrogenation of oxygen-containing functional groups and free radicals formed during pyrolysis. The evolution curves of H₂O and CH₄ had different peak distributions and evolution temperatures under H₂ and Ar, suggesting the different reaction mechanism during pyrolysis in different atmosphere. The evolution curves also revealed the different structural characteristics among vitrinite, inertinite and the parent coal.     

Computational and experimental study of the effects of adding dimethyl ether and ethanol to nonpremixed ethylene/air flames

Two sets of axisymmetric laminar coflow flames, each consisting of ethylene/air nonpremixed flames with various amounts (up to 10%) of either dimethyl ether (CH₃-O-CH₃) or ethanol (CH₃-CH₂-OH) added to the fuel stream, have been examined both computationally and experimentally. Computationally, the local rectangular refinement method, which incorporates Newton's method, is used to solve the fully coupled nonlinear conservation equations on solution-adaptive grids for each flame in two spatial dimensions. The numerical model includes C6 chemical kinetic mechanisms with up to 59 species, detailed transport, and an optically thin radiation submodel. Experimentally, thermocouples are used to measure gas temperatures, and mass spectrometry is used to determine concentrations of over 35 species along the flame centerline. Computational results are examined throughout each flame, and validation of the model occurs through comparison with centerline measurements. Very good agreement is observed for temperature, major species, and several minor species. As the level of additive is increased, temperatures, some major species (CO₂, C₂H₂), flame lengths, and residence times are essentially unchanged. However, peak centerline concentrations of benzene (C₆H₆) increase, and this increase is largest when dimethyl ether is the additive. Computational and experimental results support the hypothesis that the dominant pathway to C₆H₆ formation begins with the oxygenates decomposing into methyl radical (CH₃), which combines with C2 species to form propargyl (C₃H₃), which reacts with itself to form C₆H₆.     

On the effect of molecular and hydrocarbon-bonded hydrogen on carbon particle formation in C3O2 pyrolysis behind shock waves

The effect of H₂ and C₂H₂ addition on particle formation in the pyrolysis of C₃O₂/Ar mixtures was studied behind reflected shock waves. An existing reaction mechanism for the pyrolysis of highly-diluted C₃O₂ in argon was expanded to conditions with higher C₃O₂ concentrations (up to 33 volume%) at elevated pressures and high temperatures and was validated against experimental data. The simulations for the gas-phase chemistry were performed with the program CHEMKIN. The heterogeneous particle formation was modeled by post-processing using the program PREDICI relying on the Galerkin method. It was found that in C₃O₂/H₂/Ar pyrolysis, the induction times and rate constants of particle formation do not differ significantly from those of pure C₃O₂/Ar pyrolysis. However, the presence of H₂ reduced the particle volume fraction, the mean diameter of particles, the particle number density, and the maximum temperature rise of the mixture. Hydrocarbon-bonded hydrogen in C₃O₂/C₂H₂/Ar pyrolysis caused significantly increased induction times for particle formation, decreased particle volume fractions, and decreased temperature rises. The different reaction channels for carbon particle formation were identified in view of the role of hydrogen. An alternating reaction channel including C₂ species played an important role in forming polycyclic aromatic hydrocarbons (PAH) in the mixtures.     

The ReSER-COG process for hydrogen production on a Ni–CaO/Al2O3 complex catalyst

The reactive sorption-enhanced reforming process of simulated coke oven gas (ReSER-COG) was investigated in a laboratory-scale fixed-bed reactor with Ni–CaO/Al₂O₃ complex catalyst. Simulated coke oven gases that are free of or contain C2+ hydrocarbons (C₂H₄, C₂H₆, C₃H₆, C₃H₈) have been studied as feed materials of the ReSER process for hydrogen production. The effects of temperature, steam to methane molar ratio (S/CH₄) and carbon space velocity on the characteristics of ReSER-COG were studied. The results showed that the hydrogen concentration reaches up to 95.8% at a reaction temperature of 600 °C and a S/CH₄ of 5.8 under normal atmospheric pressure conditions. This reaction temperature was approximately 200 °C lower than that of the coke oven gas steam reforming (COGSR) processes used for the hydrogen production. The amount of H₂ generated by ReSER-COG was approximately 4.4 times more than that produced by the pressure-swing adsorption (PSA) method per unit volume of COG. The reaction temperature was 50 °C lower when simulated COG with C2+ was used, as opposed to when COG without C2+ was used. The complex catalyst has a better resistance of coking during the ReSER-COG process when C2+ gas is present.     

Plate reactor as an analysis tool for rapid pyrolysis of biomass

This work presents a study of the performance of the modified plate reactor by rapid pyrolysis experiments with different biomass samples (MDF, bark pine and Avicel cellulose). The use of the plate instead of a grid allowed us to achieve a more homogeneous temperature distribution across the plate and, therefore, biomass sample. The mass yields of the major pyrolysis products CO, CO₂, C₂H₂, CH₄, C₂H₄ and C₂H₆ are measured as a function of the holding time (from 0 to 50 s) for a number of the final temperatures (from 435 to 1100 C) using the novel approach to quantitative FTIR analysis of biomass pyrolysis spectra. Special care was taken to demonstrate the influence of the secondary tar cracking on the yields of the permanent gases. Yields of major permanent gases plotted versus each other on a logarithmic scale show two distinctive regions reflecting primary and secondary kinetic processes. The experiments show that the modified plate reactor can be used for studying the kinetics of the primary decomposition of the biomass at temperatures ≤600 C.     

Thermogravimetric and mass spectrometric analysis of powdered pine bark

Using thermal analysis and mass spectrometry, this study examined samples of powdered pine bark by subjecting them to: (a) complete combustion, (b) partial combustion, and (c) pyrolysis. For each of the examined samples, which heated at the rate of 30°C min^?1, temperature regions corresponded to moisture loss and the degassing process. Global and local maximum values of ionic currents representing H₂O, CO₂, CO, and additionally for hydrocarbons such as CH₄, C₂H₄, and C₂H₅ for pyrolysis were identified. Based on the recorded values of ionic currents of hydrocarbons in the helium atmosphere, C₂H₅ dominance was determined at T ≤ 415°C, and CH₄ dominance was determined at T > 415°C. Assuming first-order kinetics, thermogravimetric data were analyzed by the Arrhenius type model, and kinetic parameters were determined.     

Study of the Reaction Mechanisms of Hydrocarbons with Calcium Sulfate

In this article, thermal simulation experiments on the reactions in TSR process (CH₄-CaSO₄, C₂H₆-CaSO₄, and C₃H₈-CaSO₄) were carried out using autoclave at high temperature and high pressure. The gaseous and solid products were characterized by some advanced analytical methods. On the basis of the experimental results, the reaction mechanisms were tentatively investigated. It was found that three reactions can proceed to produce H₂S, H₂O, and CaCO₃ as the main products at the temperature range of 450–700°C. The high simulation temperatures also resulted in the production of undesired material. The results obtained in this article can provide important information for the investigation on the natural gas destruction in gas reservoirs.     

Experimental study of the pyrolysis of waste bitumen for oil production

This work focuses on bitumen slow pyrolysis. Mass and energy yields of oil, solid and gas were obtained from pyrolysis experiments using a semi-batch reactor in a nitrogen atmosphere, under three non-isothermal conditions (maximum temperature: 450 °C, 500 °C and 550 °C). The effect of temperature on the product yields was discussed. The gas compositions were analysed using gas chromatography (GC) and the heating value of oil and solid residue was also measured. Using a thermo-gravimetric analyser, kinetic parameters were evaluated through Ozawa-Flynn-Wall (OFW) method. Results showed that oil yield is maximum at 500 °C (50%). Moreover, gas yield increased with increasing pyrolysis temperature from 18% to 36%. On the other hand, solid yield showed an opposite trend: it decreased from 39% to 32%. As regard energy yields, they showed a similar trend with the mass ones. H_2, CH₄, C₂H₄, C₂H₆ and C₃H₈ are the main components of the produced gas phase. It has been noticed that the recovery of bitumen to liquid oil through pyrolysis process had a great potential since the oil produced had high calorific value comparable with commercial fuels.