Pyrolysis Of Toluene Research Articles

Pyrolysis behaviors of biomass tar-related model compounds catalyzed by Ni-modified HZSM-5 molecular sieve

To study the pyrolysis process and path of biomass tar, this paper took toluene as the biomass tar model compound, elected Ni-modified HZSM-5 molecular sieve as the catalyst, and established the catalytic pyrolysis process of toluene. By optimizing the process conditions of HZSM-5 catalyst modification and catalytic pyrolysis process of toluene, and comprehensively considering the indicators of catalyzing pyrolysis of toluene as biomass tar model compound, the pyrolysis behavior of aromatic tar model compounds catalyzed by Ni-modified HZSM-5 catalyst was deeply analyzed. Finally, the stability of the Ni-modified HZSM-5 catalyst was investigated with a pyrolysis time of 8 h. The best process conditions of Ni-modified HZSM-5 catalyst were obtained: SiO2/Al2O3 of 25, Ni loading of 8 wt%, and pyrolysis temperature of 700 ℃. The catalytic pyrolysis path of toluene as biomass tar model compound was clarified for the cracking and reforming of toluene for gas production, condensation and reforming reaction of liquid phase, and action of carbon deposition. The Ni-modified HZSM-5 molecular sieve shows excellent catalytic properties and application prospects, providing theoretical reference and data support for further designing and enhancing the structure of such catalysts and promoting tar removal efficiency.

Impact of Methanol and Butanol on Soot Formation in Gasoline Surrogate Pyrolysis: A Shock-Tube Study.

The influence of methanol and butanol on soot formation during the pyrolysis of a toluene primary reference fuel mixture with a research octane number (RON) of 91 (TPRF91) was investigated by conducting shock-tube experiments. The TPRF91 mixture contained 17 mol % n-heptane, 29 mol % iso-octane, and 54 mol % toluene. To assess the contribution of individual fuel compounds on soot formation during TPRF91 pyrolysis, the pyrolysis of argon diluted (1) toluene, (2) iso-octane, and (3) n-heptane mixtures were also studied. To enable the interpretation of the TPRF91 + methanol and TPRF91 + butanol experiments, the influence of both alcohols on soot formation during the thermal decomposition of toluene and iso-octane was also investigated in a separate series of measurements. Pyrolysis was monitored behind reflected shock waves at pressures between 2.1 and 4.2 bar and in the temperature range of 2060-2815 K. Laser extinction at 633 nm was used to determine the soot yield as a function of reaction time. For selected experiments, the temporal variation in temperature was also measured via time-resolved two-color CO absorption using two quantum-cascade lasers at 4.73 and 4.56 μm. It was found that soot formed during TPRF91 pyrolysis is primarily caused by the thermal decomposition of toluene. Adding methanol to TPRF91 results in a slight reduction of soot formation, whereas admixing butanol results in shifting soot formation to higher temperatures, but in that case, no overall soot reduction was observed during TPRF91 pyrolysis. Measured soot yields were compared to simulations based on a previous and an updated version of a detailed reaction mechanism from the CRECK modeling group [Nobili, A.; Cuoci, A.; Pejpichestakul, W.; Pelucchi, M.; Cavallotti, C.; Faravelli, T. Combust. Flame 2022; 10.1016/j.combustflame.2022.112073]. Rate-of-production analyses for reactions involving BINS at different experimental conditions were carried out. Although in the case of TPRF91 and toluene pyrolysis, no quantitative agreement was obtained between the experiment and simulation, the comparison nevertheless shows that the new version of the CRECK mechanism is a significant improvement over the previous one. In the case of n-heptane decomposition and iso-octane pyrolysis with and without alcohols, the updated reaction mechanism shows excellent agreement between simulation and measured soot yields.

Invisible active sites of Ni-Co alloy to toluene pyrolysis and hydrogen production at ultra-low temperature

Environmental problems caused by the utilization of fossil energy are becoming more and more serious, so now more attention has been paid to the use of renewable energy. Pyrolysis of biomass is a method that convert biomass energy into hydrogen, but this method is subject to the performance of the catalyst for the pyrolytic reaction. In this study, NiCo2O4 was synthesized by coprecipitation method and examined by microstructure and textual characterizations. The ability of NiCo2O4 to pyrolyze toluene and produce hydrogen was evaluated by temperature-programmed experiment and lifetime test. It was found that the sample could pyrolyze toluene at the concentration of 1500 ppm at 300 °C with a hydrogen production of 0.6%, suggesting toluene was completely pyrolyzed. In the longevity test, toluene can be completely pyrolyzed for at least 5 h at 400 °C, with a high hydrogen yield of above 80% maintained during the pyrolysis process. As the pyrolysis reaction progresses, NiCo2O4 was gradually reduced to nickel-cobalt alloy by hydrogen from the pyrolysis of toluene, indicating the actual active site of nickel-cobalt alloy. This study gives a hint for developing a good catalyst for the ultra-low temperature biomass pyrolysis to produce hydrogen.

Synergistic modification of Ca/Co on Ni/HZSM-5 catalyst for pyrolysis of organic components in biomass tar

This study used ultrasonic-assisted over-impregnation method to prepare Ni/HZSM-5 catalysts modified by Ca/Co for pyrolysis of toluene. The results showed that the additive Ca promoted the grain refinement of metallic nickel, and interacted with Ni to form the NiO-CaO solid solution, which enhanced anti-sulfidation and anti-coking properties of catalysts and improved the reforming reaction of tar. For Ni-Ca catalysts, the highest yields of H2 and CH4 were 40.2 mL/g and 69.3 mL/g, the toluene conversion was 86.2% and the liquid yield was 35.3% at 800 ℃. In order to reduce the liquid yield and further improve the gas yield, the additive Co was supported on Ni-4 wt%Ca/HZSM-5 catalyst with the loading of 0.1–2 wt%. Ni-Co solid solution alloys with small particle size and uniform distribution were formed on the surface of HZSM-5 carrier, which made the reforming reaction move to the low temperature direction and promoted the reduction of Ni species. And during the loading process, the two additive metals, Ca and Co, were combined with each other in the form of oxides, further improving the mechanical strength and reaction stability of catalysts. The Ni-4 wt%Ca-0.1 wt%Co/HZSM-5 catalyst showed the best pyrolysis performance. The liquid recovery rate was decreased by 14.6% and the yields of H2 and CH4 were increased by 17.7% and 8.9% at 800 ℃. Most importantly, with the increase of pyrolysis temperature from 700 °C to 900 °C, the yield of pyrolysis gases and toluene conversion increased significantly. Especially, at 900 °C, the yields of H2 and CH4 produced over Ni-4 wt%Ca-0.1 wt%Co catalyst were 120.3 mL/g and 107.4 mL/g, and toluene conversion reached 98.6%. Ni-4 wt%Ca-0.1 wt%Co still maintained high catalytic activity after secondary regeneration at 900 °C.

Particle volatility, size distribution and PAH/alkyl-PAH profiles during toluene pyrolysis in a flow reactor

Particle volatility, size distribution and PAH/alkyl-PAH profiles during toluene pyrolysis in a flow reactor

Catalytic pyrolysis of toluene as biomass tar model component using Ni/HZSM-5 modified by CeO2 and MgO promoters

Thermochemical conversion technology is a promising chemical method for removal of biomass tar. In this study, Ni/HZSM-5 catalyst modified by CeO2 and MgO promoters were prepared by ultrasonic-assisted excessive impregnation method. Toluene was selected as the representative model component of biomass tar, and the pyrolysis experiments were carried out in a tubular fixed bed reactor. Fresh and reacted catalysts have been characterized. The results revealed a similar initial activity for different loadings of same promoter. The stability of Ni-Ce catalysts increased gradually with increasing of Ce loading. In particular, Ni-4%Ce/HZSM-5 catalyst has the best catalytic activity with the toluene conversion of 94.5%, the yield of total gas of 107 mL/g, the gaseous efficiency of 68 wt.%. The BET surface areas as large as 206.9 m2/g with an average pore size of 3.2 nm assisted NiO particles dispersed on the surface of HZSM-5 support. Although the performance of Ni-4%Ce/HZSM-5 catalyst was better, the surface of its also formed char with an elongated fiber. However, the low-catalytic performance of Ni-Mg/HZSM-5 was due to the instability of active center NiO-MgO solid solution. This study revealed the influences of promoter types, promoter loadings, and the potential mechanism of similar catalytic performance on the preparation process of Ni-based catalysts.

Pyrolysis of biomass Tar model compound with various Ni-based catalysts: Influence of promoters characteristics on hydrogen-rich gas formation

This paper studied the conditions and mechanism of hydrogen-rich gas produced from catalytic pyrolysis of toluene by various Ni-based catalysts in a fixed-bed reactor. We specifically focused on the effect of different promoters and promoter characteristics on the physicochemical properties of Ni/HZSM-5 -based catalyst. The results revealed that, a similar initial activity for Ni-catalysts modified different promoters was tested with toluene conversion higher than 85%. The Fe-modified Ni/HZSM-5 catalyst has the most effective catalyst for hydrogen-rich gas production with the gaseous efficiency of 63.4 wt%, mainly gas (H2, CH4) yield of 118.6 mL/g-toluene, H2 yield of 53.4 mL/g-toluene at 800 °C pyrolysis for 40 min. The smaller crystal particles (3.1 nm), high surface area (219.5 m2/g), and sufficient loading quality (4 wt%) for Ni–Fe catalysts provided efficient active sites and promoted the pyrolysis process of toluene. The activity and stability of catalysts were also improved by Ce-modified Ni/ZSM-5 catalyst with the highest gaseous efficiency of 68.0 wt%, but the H2 yield of 40.3 mL/g-toluene was lower. However, Ni–Mg/HZSM-5 catalyst has lowest activity and stability. The catalyst deactivation is associated with nickel sintering and coke formation. After the Ni–Fe/HZ5 catalyst was regenerated twice, it still maintained high catalytic activity.

Influences of propylene/propyne addition on toluene pyrolysis in a single-pulse shock tube

To explore the potential interactions between toluene/benzyl and the common C3 combustion intermediates, toluene-propylene and toluene-propyne co-pyrolysis is studied in the current work by taking neat toluene pyrolysis as a reference. Experiments are carried out at a nominal pressure of 20 bar over a temperature range of 1050−1700 K, using a single-pulse shock tube facility coupled to the gas chromatography-mass spectrometry speciation diagnostic technique. Temperature-dependent mole fraction profiles are obtained for numerous species ranging from small-molecule products to three-ring polycyclic aromatic hydrocarbons (PAHs). A kinetic model, which has been under development in our serial works, is extended by including the interplays between toluene/benzyl and propylene/propyne chemistry. The updated model can satisfactorily predict the measurements, regarding the absolute mole fractions as well as the variation trends brought by different initial fuel compositions. Increased reactivity is observed in the conversion of toluene with the presence of propylene or propyne, while the consumption rates of the studied C3 fuels are barely influenced by toluene. Benzene formation is facilitated by the C3+C3 reactions introduced by the C3 fuels. The pyrolysis of propylene (or propyne) significantly enhances the level of C1−C3 molecules/radicals that further react with aromatic species. For instance, the reactions of benzyl+propyne result in much higher mole fractions and lower speciation temperature windows of indene and naphthalene in toluene-propylene (or propyne) co-pyrolysis. The reactions with small hydrocarbons result in reduced levels of benzyl and other C7 radicals in the reaction system in toluene- propylene (or propyne) co-pyrolysis. Consequently, for the PAHs which are mainly formed through C7+C7 reactions, such as bibenzyl and phenanthrene, the mole fractions are lowered by the addition of propylene (or propyne). Propyne has more obvious influences on the species pool of toluene pyrolysis than propylene, because the effective C7C3 interactions are mostly through the reactions between toluene/benzyl and propyne/propargyl in both cases of toluene-propylene and toluene-propyne co-pyrolysis.

Detailed experimental and kinetic modeling study of toluene/C2 pyrolysis in a single-pulse shock tube

Abstract A combined experimental and kinetic modeling study is carried out to explore the influences of acetylene and ethylene addition on the species formation from toluene pyrolysis. Experiments are conducted separately with four different argon-diluted binary toluene/C2 mixtures in a single pulse shock tube at a nominal pressure of 20 bar over a temperature range of 1150−1650 K. All the experimental mixtures contain about 100 ppm toluene and different amounts of C2 fuels (50, 216, 459 ppm acetylene and 516 ppm ethylene). Species concentrations as a function of the temperature are probed from the post-shock gas mixtures and analyzed through the gas chromatography/gas chromatography-mass spectrometry techniques. A kinetic model is developed, which successfully predicts the absolute species concentration measurements as well as the changes brought by the varied fuel compositions. With the neat fuel decomposition profiles as a reference, both fuel components exhibit increased reactivity in the pyrolysis of all studied binary mixtures, indicating the existence of obvious synergistic effects. In particular, such effects become more remarkable when increasing the initial acetylene concentration. This essentially results from the addition-elimination reaction of a toluene fuel radical and a C2 fuel molecule leading to a C9 molecule and a hydrogen atom. Indene is identified as the predominant C9 product in all studied cases, and its peak concentrations sharply increase with the initial acetylene contents in toluene-acetylene pyrolysis. On the other hand, indane, produced from the addition-elimination reaction between benzyl and ethylene, is only detected at trace levels in toluene/ethylene pyrolysis. This indicates a relatively weaker interaction between benzyl and ethylene, compared to that of benzyl and acetylene. Apart from the increased concentrations of hydrogen atoms and C9 aromatics, interactions between toluene and C2 fuels also directly result in a reduced level of C7 radicals in the reaction system. Overall, PAH species can be divided into two groups according to the way their peak concentrations varying with the initial fuel compositions. For those largely depending on benzyl reactions, such as bibenzyl, biphenylmethane, fluorene and phenanthrene, the peak concentrations decrease with the added C2 fuels. In contrast, increasing trends are observed in the peak concentrations of the PAHs which rely on indenyl as a precursor, including naphthalene, methyl-indene, benzofulvene and acenaphthalene.

Unraveling synergistic effects on pyrolysis reactivity and indene formation in co-pyrolysis of toluene and acetylene

Synergistic effect is one of the most important interactions between different fuel components and is very influential on combustion characteristics such as polycyclic aromatic hydrocarbon (PAH) and soot emissions, pyrolysis/oxidation reactivity and so on. In order to explore the potential synergistic effects between aromatics and open-chained fuels, pure toluene pyrolysis, pure acetylene pyrolysis and co-pyrolysis of toluene and acetylene were investigated in a flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry at 1057–1340 K and 1 atm. Mole fractions of fuels and key products including both stable and reactive ones were evaluated. The experimental results indicate that in the co-pyrolysis of toluene and acetylene, the decomposition of both fuels is greatly stimulated and the formation of indene is significantly improved compared to the pyrolysis of pure toluene and pure acetylene. As a result, remarkable synergistic effects can be observed on pyrolysis reactivity and indene formation. A kinetic model for co-pyrolysis of toluene and acetylene was updated from our previous toluene model and was validated against the new data. The modeling analysis reveals that the unimolecular decomposition reaction of toluene producing benzyl radical and H atom is the chain-initiation reaction in both pure toluene pyrolysis and co-pyrolysis of toluene and acetylene. In the pure toluene pyrolysis, the self-combination reaction forming bibenzyl dominates the consumption of benzyl radical and results in strong chain termination. In the co-pyrolysis of toluene and acetylene, instead of the chain-termination reaction, a circulating reaction sequence initiating from the reaction between benzyl radical and acetylene continuously converts toluene and acetylene to indene and H2, which can explain the observed synergistic effects on pyrolysis reactivity and indene formation in the co-pyrolysis of toluene and acetylene.

Insight into an invisible active site presented in the low temperature pyrolysis of toluene by CoMn spinel catalyst

In this work, CoMn spinel (MnCo2O4+δ) was prepared from CoMn LDH and was applied as a catalyst toward toluene pyrolysis. Spinel samples with different degrees of crystallinity were evaluated by isothermal and stepwise heating experiments, as well as feeding toluene with different concentrations. Especially for the spinel with high degree of crystallinity, results exhibited a relatively low pyrolysis temperature of 400 °C, a high toluene conversion rate of ~ 100%, a large H2 production and an acceptable benzene formation. More importantly, by various characterization techniques, an invisible active site was detected and believed to be formed by the reaction of CoMn spinel with toluene, and was designated as manganosite-cobalt nanoparticles supported on carbon nanotubes (MnO-Co/CNTs), which significantly promoted the degradation and carbonization reactions in the low temperature pyrolysis of toluene.

Probing PAH formation chemical kinetics from benzene and toluene pyrolysis in a single-pulse shock tube

Benzene and toluene were pyrolyzed under highly argon-diluted conditions at a nominal pressure of 20 bar in a single-pulse shock tube coupled to gas chromatography/gas chromatography–mass spectrometry (GC/GC–MS) diagnostics. Concentration evolutions of polycyclic aromatic hydrocarbon (PAH) intermediates were measured in a temperature range of 1100–1800 K by analyzing the post-shock gas mixtures. Different PAH speciation behaviors, regarding types, concentrations and formation temperature windows, were observed in the two reaction systems. A kinetic model was proposed to predict and interpret the measurements. Through a combination of experimental and modeling efforts, PAH formation patterns from species pools of benzene and toluene pyrolysis were illustrated. In both cases, channels leading to PAHs basically originate from the respective fuel radicals, phenyl and benzyl. Due to the higher thermal stability of benzene, the production of phenyl, and thus most PAH species, occur in higher temperature windows, in comparison to the case of toluene. In benzene pyrolysis, benzyne participates in the formation of crucial PAH species such as naphthalene and acenaphthylene. Phenyl self-recombination takes considerable carbon flux into biphenyl, which serves as an important intermediate leading to acenaphthylene through hydrogen loss and ring closure. The resonantly-stabilized benzyl is abundant in toluene pyrolysis, and its decomposition further produces other resonantly-stabilized radicals such as fulvenallenyl and propargyl. Barrierless addition reactions among these radicals are found to be important sources of PAHs. Fuel-specific pathways have pronounced effects on PAH speciation behaviors, particularly at lower temperatures where fuel depletion is not completed within the reaction time of 4.0 ms. Contributions from the commonly existing Hydrogen-Abstraction-Carbon-Addition (HACA) routes increase with the temperature in both cases.

Catalytic conversion of toluene over a biochar bed under an inert atmosphere – The comparison of chars from different types of wood and the role of selected metals

In this paper, toluene, a tar-representing compound, was used in pyrolytic conversion tests with a wood-derived char catalyst. The decomposition mainly occurred via two competing heterogeneous reactions; the favoured reaction led to coke formation on the catalyst bed. With char saturation of the carbon deposit, a second demethylation reaction gained significance, until selectivity towards benzene formation reached 12–16%. By-products of the secondary reaction (xylenes, ethylbenzene and styrene) were also detected; however, no gas-phase toluene decomposition occurred. The principles of toluene conversion were the same for all of the examined chars from the different tree species. However, a quantitative difference was observed between the chars from the wood from coniferous and deciduous trees. Pine yielded char with less mesopores and active sites and thus demonstrated a lower efficiency as a catalyst for toluene decomposition. An assessment of alkali and alkaline earth metals importance revealed that, while their presence in the char strongly enhances its oxidation rate, they did not affect the toluene pyrolysis.

Cobalt Carbide from Co–Mn Layered Double Hydroxide: Highly Efficient Catalyst for Toluene Pyrolysis

The cobalt carbide (Co2C) innovatively prepared from Co–Mn layered double hydroxide (CoMn LDH) has been investigated and evaluated toward its alternative synthesis conditions and different catalyti...

Toluene pyrolysis in an electric ARC: Products analysis

Toluene pyrolysis in a submerged carbon arc produced at least 72 different molecular species as detected by gas-chromatography coupled with mass spectrometry (GC-MS). The most abundant products found were bibenzyl (1,2-diphenylethane), naphthalene and biphenylene. Furthermore, also diethynylbenzene isomers, fluorene, diphenymethane, indene and biphenyl were produced in appreciable amounts. The formation mechanisms of these and other minor products are discussed mainly in the light of the benzyl radical and its decay into other products. Among polyynes, only 1,3,5,7-octatetrayne was produced above 1% relative yield. The results are discussed in comparison to the products detected in toluene pyrolysis under other experimental conditions, such as shock tube pyrolysis and toluene flames. Furthermore, a comparison with the products obtained from the benzene pyrolysis is reported.

Influence of aliphatic side chains of aromatic hydrocarbons on soot formation: Experimental and numerical investigation

The effect of aliphatic side chains in the feedstock on soot formation was studied with experimental and numerical simulation. Feedstocks of ethylbenzene, xylene, toluene, and benzene were pyrolyzed at different residence times and temperatures, and the particle size distribution (PSD) of the formed soot was measured. The initial nucleation rates of soot during ethylbenzene or toluene pyrolysis was high. However, after a long residence time, the amount of soot produced from benzene pyrolysis became higher than for these feedstocks. This result suggests that at long residence times, the growth rate of soot from benzene is higher than those of ethylbenzene and toluene. Numerical simulation for the pyrolysis of ethylbenzene, toluene, and benzene was conducted with the KAUST PAH Mechanism 2 (KM2) model, and the prediction accuracy was improved by adding some new reactions. The simulations were performed at two conditions similar to the experimental ones: The production rate of polycyclic aromatic hydrocarbons (PAHs) was very high at the beginning of reactions of ethylbenzene and toluene, indicating high rates of soot nuclei generation. In benzene pyrolysis, modification of the KM2 model led to a higher predicted PAH concentration than that with the original KM2. Most of the reactions we added to the KM2 model are those of PAH growth by phenyl addition (PA). Therefore, the PA mechanism would be an important reaction pathway for PAH growth in the pyrolysis of benzene.

Toluene decomposition on mesoporous templates to form carbon materials and residue characteristics

Santa Barbara Amorphous-15 (SBA-15) was selected as the template and Ni as the catalyst. The BET surface areas of SBA-15 and Ni-SBA-15 were 626 ± 55 and 458 ± 65 m2/g, respectively, and the pore sizes were 45 ± 5 and 48 ± 5 Å, respectively. These materials were identified as mesoporous and were composed of a series of small rods into organized bundles and an orderly hexagonal structure. Carbon material was synthesized at 750–950 °C using toluene as the carbon source on the templates. Results showed that the average pore diameter increased with a decrease in BET surface area and pore volume for the formation of carbon materials on SBA-15 and Ni-SBA-15. Only soot particles remained on the surface of SBA-15, but toluene accompanied by Ni-SBA-15 formed carbon nanotubes at 850 and 950 °C. There was less than 15% toluene to form carbon materials on the templates, and most of the toluene decomposed to form tar and exhaust gas. During toluene pyrolysis, benzene, ethyl toluene, toluene, and xylene were the main VOCs in the gas phase. Naphthalene and pyrene were the primary PAHs during toluene breakdown on SBA-15 and Ni-SBA-15. The work indicates that the Ni catalyst could decrease VOC concentration and enhance the formation of carbon materials.

Hydropyrolysis of n-Hexane and Toluene to Acetylene in Rotating-Arc Plasma

Thermal plasma pyrolysis is a powerful technology for converting waste or low-value materials to valuable gaseous hydrocarbons. This paper presents for the first time the hydropyrolysis of n-hexane and toluene in a rotating-arc plasma reactor. Effects of the mole ratio of H/C in the feed, power input and magnetic induction were investigated to evaluate the reaction performance. A lower H/C ratio could lead to a lower yield of C2H2 and lower specific energy consumption, and there existed an optimum range of power input for both n-hexane and toluene pyrolysis within the investigated range. The yield of C2H2 in n-hexane and toluene pyrolysis could reach 85% and 68%, respectively, with respective specific energy consumption (SEC) of 13.8 kWh/kg·C2H2 and 19.9 kWh/kg·C2H2. Compared with the results reported in literature, the rotating-arc plasma process showed higher C2H2 yield and lower energy consumption, which is attributed to the better initial mixing of the reactant with the hot plasma gas and the more uniform temperature distribution.

Pyrolytic toluene conversion to benzene and coke over activated carbon in a fixed-bed reactor

The catalytic decomposition of tar compounds is an important issue in the cleaning and upgrading of gasification product gases. This work focuses on toluene pyrolysis in a quartz tube reactor with a fixed bed of activated carbon. A toluene to benzene and coke conversion mechanism is also proposed. Liquid decomposition products were analysed with GC-FID. The ash content in the spent carbon was measured, allowing for the determination of coke deposit growth on the carbon surface. Pyrolysis runs were performed at temperatures ranging from 650 to 800°C and with varying toluene feeding times. It was determined that toluene conversion is maintained above 90% for the first 20min of pyrolysis at 800°C. At this initial time, pronounced coking on the carbon surface was observed. Subsequently, toluene conversion decreased, coke deposition was hindered and benzene, a decomposition side product, yield was greatly enhanced. At lower temperatures coking is inhibited and toluene conversions were relatively low. For short, 10min feeding times and at low temperatures, the benzene share of overall converted toluene is significant. The toluene to benzene conversion model, necessarily based on both experimental results and the literature, shows that coke and benzene creation are competing reactions.

The effect of ZSM-5 catalyst support in catalytic pyrolysis of biomass and compounds abundant in pyrolysis bio-oils

Supported ZSM-5 is commonly used for in-situ biomass pyrolysis vapor upgrading in fluidized bed reactors. In this work, we investigate the effects of catalyst support on the pyrolysis product distribution by studying pyrolysis of woody biomass and bio-oil derived model compounds. Specifically, miscanthus, toluene and furan are catalytically pyrolyzed over bulk ZSM-5, supported ZSM-5 and a commercial Al2O3 support. The pyrolysis product distributions of biomass and each model compound are presented and discussed. The coke formed on the catalysts and support, which is also responsible for catalyst deactivation, is analyzed using temperature programmed oxidation (TPO). It is shown that pyrolysis of miscanthus, toluene and furan over supported ZSM-5 produces less liquid products, particularly mono-aromatic hydrocarbons, than over bulk ZSM-5, mainly due to the dilution of Brønsted acid sites by the catalyst support. The Lewis acidity of the Al2O3 support promotes alkylation and cyclization of propylene leading to enhanced benzene production. The Lewis acidity of the support also enhances coke production with a less condensed structure, while selectivity to poly-aromatics is deteriorated.