Formation Of Solid Products Research Articles

Effect of Different Anions Upon the WO₃ Morphology and Structure.

In this study the effects of various anions (SO2-₄, ClO-₄ and PO3-₄) were investigated on the hydrothermal treatment of WO₃ from Na₂WO₄ and HCl at 180 and 200 °C. The products were analyzed by XRD and SEM. With the usage of SO2-₄ the obtained product was hexagonal (h-) WO₃ in the form of nanorods at both temperatures. Applying ClO-₄ resulted in a mixture of WO₃·0.33H₂O and small amount of m-WO₃ at 180 °C and pure WO₃·0.33H₂O at 200 °C. The morphology was consisted of cuboid shapes arranged into spherical structures at 180 °C and longitudinal ones at 200 °C. By the application of PO3-₄ no product formed at either temperature. Using the combination of SO2-₄, and ClO-₄ the product was h-WO₃ at both 180 and 200 °C with rod-like crystals; thus, the effect of ClO-₄ was overdominated by the SO2-₄ions. Utilization of PO3-₄ together with SO2-₄, and/or ClO-₄ resulted again in no product, meaning that adding PO3-₄ to the reaction mixture completely blocks the hydrothermal formation of solid products by forming water soluble phosphotungstic acids.

CO2 absorption and ion mobility in aqueous choline-based ionic liquids

CO2 absorption and ion mobility are investigated in a series of 50/50 wt% aqueous solutions of choline-based ionic liquids with different cations and anions: [N1,1,4,2OH][Threo], [N1,1,5,2OH][Threo], [N1,1,6,2OH][Threo], [N1,1,5,2OH][β-ala] and [N1,1,5,2OH][Tau]. The process of CO2 absorption was completed in an hour reaching maximum of absorption capacity 0.07–0.10 wt% to ionic liquid (by 0.4–0.6 molar ratios). A rapid CO2 absorption is observed by the formation of solid product as a result of reaction between CO2 molecule and the ionic liquid. Diffusion coefficients of the cation and anion in the mixture are comparable while the diffusivity of water molecules is found to be quite different from the ions. In the process of CO2 absorption, an increase in the diffusivity of ions is observed due to the precipitation of solid products and depletion of ions contents in the liquid phase of the system. 13C NMR measurements of diffusivity of CO2 enriched with 13C isotope showed that a part of the absorbed CO2 remained in the liquid phase being physically and chemically bound to ions. The ionic liquid is re-cycled by evaporating water and releasing CO2 molecules using vacuum and temperature.

Experimental and Kinetic Study of Magnesium Extraction and Leaching from Laterite Nickel Ore by Roasting with Ammonium Sulfate

Laterite-nickel ore was roasted with ammonium sulfate to extract magnesium by a single-factor experiment, and an orthogonal test was employed to optimize the conditions. The optimum roasting conditions were: calcination temperature, 450°C; calcination time, 120 min; molar ratio of reactants, 2 : 1; granularity <80 µm. The kinetics of the roasting process were also studied. The experimental results showed that the extraction rate of magnesium increased as the calcination temperature increased. The reaction rate of magnesium is in accordance with the shrinking non-reacted nuclear model for the solid product formation reaction. The roasting reaction is controlled by internal diffusion. The apparent activation energy is E = 18.96 kJ mol–1. The kinetic equation is $${\text{1}} + {\text{2}}\left( {{\text{1}} - {\alpha\text{}}} \right) - {\text{3}}{{\left( {{\text{1}} - {\alpha\text{}}} \right)}^{{{{\text{2}} \mathord{\left/ {\vphantom {{\text{2}} {\text{3}}}} \right. \kern-0em} {\text{3}}}}}} = {\text{0}}{\text{.05061exp}}\left[ { - {{{\text{18}}{\text{963}}} \mathord{\left/ {\vphantom {{{\text{18}}{\text{963}}} {\left( {RT} \right)}}} \right. \kern-0em} {\left( {RT} \right)}}} \right]t.$$ A single factor experiment and orthogonal test were carried out to optimize the magnesium leaching process reaction conditions. The optimum conditions of the leaching process were: leaching temperature, 60°C; leaching time, 60 min; liquid to solid ratio, 2.5 : 1; stirring intensity, 400 r min–1. The kinetic equation is 1 – (1 – α)2/3 = 0.3991exp(–8632/RT)t. The apparent activation energy is E = 8.63 kJ mol–1. The reaction rate of the leaching process was controlled by external diffusion.

Mechanochemical processes with the reaction-induced mechanical activation. Chemo-mechanochemical effect

The review addresses the special case of mechanical activation of solid-state chemical reactions when the stress field, strain, and defects in crystals are induced by the chemical reaction itself rather than by the external mechanical impact (chemo-mechanochemical (CMC) effect). This review presents the analysis and state-of-the-art of research activities in this area. Different cases of the CMC effect in homogeneous and heterogeneous systems are considered: with or without changes in the chemical composition, with or without formation of solid products, etc.

Chemical method of fatigue and corrosion fatigue crack growth arrest in steels by metal treatment with the special technological environment

Novel method of fatigue crack growth arrest in structural steels based on artificial creation of crack closure effect is proposed. Special technological environment is used which, falling into a crack cavity, forms solid products there. These products practically totally fill up a crack cavity and serve as a wedge which prevents crack closure during a period of unloading and, respectively, cyclic deformation in a crack tip. Fatigue crack growth curves are built for low alloyed steel without and with crack treatment which demonstrate crack arrest in a wide range of stress intensity factor (SIF) ΔK, from the threshold level up to almost fatigue fracture toughness Kfc. i.e for the whole actual range of ΔK. The peculiarity of artificial crack closure is accentuated: a decrease of effective ΔK is accompanied by an increase of a middle level of SIF therefore a risk of stress corrosion cracking and corrosion fatigue rises. This factor is especially important for long-term operated steels which lost their initial brittle fracture resistance. The interaction of active components of the technological environment with a metal at the crack surface which provides formation of solid products in a crack cavity is analyzed. Some technological aspects for practical application of the proposed method are considered.

Petrochemical feedstock from pyrolysis of waste polyethylene and polypropylene using different catalysts

In this work, thermal and catalytic pyrolysis of urban plastic waste composed of a mixture of polyethylene (PE) and polypropylene (PP) was studied. The catalysts investigated were HZSM-5, USY, NH4ZSM-5 (ZSM-5 in ammonium form), and their corresponding alkaline-treated (BHZSM-5, BUSY, and BNH4ZSM-5) or acid-leached (LHZSM-5, LUSY, and LNH4ZSM-5) forms. The catalytic pyrolysis using BHZSM-5 (ZSM-5 in alkaline form), USY, BUSY, and NH4ZSM-5 resulted in higher amounts of liquid fraction, which was composed of alkylbenzenes, naphthalenes, and olefins. Acid leaching of zeolite NH4ZSM-5 increased both the specific area and the mesopore volume, allowing an increase in the liquid and gas fractions, and a reduction in the solid fraction. BHZSM-5 zeolite showed the best catalytic performance for the production of a high amount of liquid fraction, which was virtually composed of olefinic hydrocarbons without the formation of solid products. Moreover, BNH4ZSM-5 zeolite (alkaline-treated NH4ZSM-5) was a good pyrolysis catalyst also due to its high specific area and pore volume, resulting in higher gas formation in comparison with the liquid fraction (composed mostly of alkylbenzenes), and almost no solid fraction.

Kinetic of ZrW catalyzed cellulose hydrothermal conversion: Deeper understanding of reaction pathway via analytic tools improvement

Heterogeneously catalyzed cellulose hydrolysis into value added chemicals has addressed intensive efforts of research for the past ten years. However, the mechanism of cellulose transformation promoted by a solid catalysts is far to be solved. We are thinking that this is most likely due to analysis issues. Indeed, cellulose conversion is never measured directly but deduced from TOC analysis of the aqueous phase or by weighing the solid residue at the end of the reaction. This does not correctly represent the cellulose transformation, which leads, very often, to the formation of solid products. In the present work, we report our efforts to develop a simple analytic tool based on FTIR to measure directly the cellulose conversion and the amount of solid carbon products, an essential data, rarely quantify to date. With these new analytic tools, the observed evolutions of cellulose conversion and of the products distribution with time definitively show that the solid catalyst ZrW accelerates i-the initial rate of cellulose conversion ii- the initial formation of the three main products families: chemicals detectable by HPLC, soluble polymers and solid carbon products. However, the key issue of the contact between the solid substrate and the catalyst surface is put forward by these kinetic data but remains not solved.

Insight into the effect of ZnCl2 on analytical pyrolysis behavior of cellulolytic enzyme corn stover lignin

The target of this work is to investigate the effect of impregnated ZnCl2 on the analytical pyrolysis behavior of waste cellulolytic enzyme corn stover lignin (CECL). Pyrolysis of CECL in a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) exhibited that ZnCl2 promoted the formation of solid product, resulted in high activation energies (114–236kJ/mol). The evolution amount of CO2 and H2O increased 2–3 times with ZnCl2. Pyrolysis in a pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS) showed that 4-vinylphenol and 4-vinylguaiacol exhibited high peak areas, and the formation of most monomeric phenols was substantially suppressed by ZnCl2. A possible mechanism was provided considering that ZnCl2 promoted the formation of char and non-condensable gases while suppressed the formation of bio-oil. The substantial evolution of gases could be responsible for the highly porous structure of activated carbon prepared with ZnCl2. Our work provides a foundation towards understanding the effect of ZnCl2 on lignin pyrolysis.

Numerical investigation of a non-aqueous lithium-oxygen battery based on lithium superoxide as the discharge product

It is reported lithium superoxide as the discharge product can largely decrease the charge voltage and enable a high round-trip efficiency of lithium-oxygen (Li-O2) batteries. Here, we conduct a numerical investigation of the discharge behaviors of such batteries with LiO2 as the discharge product. A mathematical model considering the mass transport and electrochemical reaction processes is first developed, which gives good agreement of the simulated discharge voltage with the experimental data. Then, with this model, the effects of electrode and electrolyte properties on the discharge performance are detailedly investigated. It is found that a thin cathode with a large porosity is favorable for a high specific capacity, and a high catalytic activity can lead to a high discharge voltage. For the cathode with different geometrical properties, it is found that the oxygen solubility and diffusivity have similar impacts on discharge capacities, but the oxygen solubility has a larger impact on energy densities. Besides, the limitations and further developments of the present model are also discussed. The results obtained from this work may give useful guidance for the discharge performance improvements of non-aqueous Li-O2 batteries, and provide implications for other energy storage systems with solid product formation such as Na-O2 batteries and Li-S batteries.

Fractionation of Degraded Lignin by Using a Water/1‐Butanol Mixture with a Solid‐Acid Catalyst: A Potential Source of Phenolic Compounds

AbstractFractionation of a lignin‐derived liquid using a water/1‐butanol mixture was investigated with the aim of developing a source of phenols. The effect of various phases on lignin depolymerization by using a water/1‐butanol mixture with a solid acid catalyst was investigated. The water/1‐butanol solvent was confirmed to be heterogeneous under the reaction conditions, and the liquid phase was essential for effective depolymerization of lignin. To make optimum use of the depolymerized lignin and to understand its chemical structure, solvent fractionation was performed by using a water/tetrahydrofuran solution, ethyl acetate, and n‐hexane as solvents. Catalytic cracking of the n‐hexane soluble fraction was performed over an iron oxide catalyst by using a high‐pressure fixed‐bed flow reactor at 673 K. The production of phenol was confirmed, and the demethoxylation reaction was examined by using model compounds. In addition, as the heavy components were extracted during the solvent fractionation, as confirmed by analysis of the molecular structures of the fractionated components, the formation of solid products could be suppressed to a level below 2.5 molC % based on lignin.

Recycling of the Electronic Waste Applying the Plasma Reactor Technology

Abstract The following paper discusses a high-temperature gasification process and melting of electronic components and computer equipment using plasma reactor technology. It analyses the marginal conditions of batch processing, as well as the formation of solid products which result from the procedure of waste processing. Attention is also paid to the impact of the emerging products on the environment.

Bio-oil upgrading in supercritical water using Ni-Co catalysts supported on carbon nanofibres

This work addresses the preparation, characterisation and screening of different Ni-Co catalysts supported on carbon nanofibres (CNFs) for use in the upgrading of bio-oil in supercritical water. The aim is to improve the physicochemical properties of bio-oil so that it can be used as a fuel. The CNFs were firstly oxidised in HNO3 and afterwards subjected to a thermal treatment to selectively modify their surface chemistry prior to the incorporation of the metal active phase (Ni-Co). The CNFs and the supported catalysts were thoroughly characterised by several techniques, which allowed a relationship to be established between the catalyst properties and the upgrading results. The use of Ni-Co/CNFs for bio-oil upgrading in supercritical water (SCW) significantly improved the properties of the original feedstock. In addition, the thermal treatment to which the fibres were subjected exerted a significant influence on their catalytic properties. An increase in the severity of the thermal treatment led to a substantial reduction in the oxygen content of the CNFs, mainly due to the removal of the less stable oxygen surface groups, which allowed their surface polarity to decrease. This decrease resulted in less formation of solid products. However, it also reduced the H/C and increased the O/C ratios of the upgraded liquid. Therefore, a compromise between the yield and the properties of the upgraded bio-oil was achieved with a Ni-Co supported on a CNF with a moderate amount of oxygen surface groups.

Bifunctional Ni‐ZSM‐5 Catalysts for the Pyrolysis and Hydropyrolysis of Biomass

AbstractIn this work, we explore pyrolysis options, namely, high pressure, H2, and metal‐loaded ZSM‐5 catalysts, to improve the limited deoxygenation capacity and reduce the excessive production of solids in biomass catalytic fast pyrolysis (CFP). Specifically, we explore the product selectivity of Miscanthus x giganteus CFP in inert or H2‐rich environments, pressures up to 450 psig, and over ZSM‐5 and Ni‐ZSM‐5. We show that higher pressures promote decarboxylation reactions, reduce the yields to liquids, and enhance the formation of solid products. Ni‐ZSM‐5 promotes decarboxylation, dehydration, and methanation reactions. The cofeeding of H2 at high pressures increases the selectivity to monoaromatic hydrocarbons with a parallel enhancement of the yield to saturated products. Solid products are reduced drastically in H2‐rich, high‐pressure experiments, and the CH4 selectivity increases. Based on these experimental findings, we present a reaction scheme that describes the impact of pressure, H2, and Ni on the product selectivity of biomass CFP.

Predicting the composition and formation of solid products in lithium–sulfur batteries by using an experimental phase diagram

Lithium-sulfur batteries discharge via the transformation of solid sulfur to solid lithium sulfide via the formation of several polysulfide species that have only been observed in solution. Reported here is the first experimental phase diagram of a S8-Li2S-electrolyte system, which is shown to be a practical tool to determine the solution composition and formation of solid (S8 and Li2S) phases in lithium-sulfur batteries. The phase diagram is constructed by the combination of measurements of the total sulfur concentration [S]T and average oxidation state (Sm-) of polysulfide solutions prepared by reaction of S8 and Li2S. The phase diagram is used to predict the equilibrium discharge/charge profile of lithium-sulfur batteries as a function of the amount of electrolyte and the onset of precipitation and dissolution of solid products. High energy batteries should operate with a minimum amount of electrolyte, where both solid S8 and Li2S will be present during most of the charge and discharge of the cell, in which case we predict the observation of only one voltage plateau, instead of the two voltage plateaus commonly reported.

The Hydrogen Evolution Reaction on Fe Electrode Material in 1 M NaOH Solution

Kinetics of hydrogen evolution reaction (HER) was investigated in 1 M NaOH solution at room temperature on a polycrystalline Fe electrode material which was electrochemically activated and unactivated. Studies of the HER were carried out using steady-state polarization and electrochemical impedance spectroscopy (EIS) measurements. It was found that for the Fe electrode material after activation atj= -320 mA cm-2for 24 h, the increase in the catalytic activity towards the HER was observed in comparison with that on the unactivated iron electrode material.Acimpedance behavior of the Fe electrode changed from a typical for smooth electrodes before activation (one time constant in the circuit) to that being characteristic for porous electrodes after activation (two time constants in the circuit). The reason for that is formation of solid products of the iron corrosion in alkaline solution which can cause passivation of the electrode surface and catalyse the HER.

Separating Electron Transfer and Product Nucleation Sites on a Model Li-O2 Battery Cathode to Explore Proximity Relationships for ORR in Aprotic Organic Electrolytes

Creating and preserving the activity of an oxygen cathode in an aprotic organic solvent is a critical barrier that must be overcome to enable energy storage with the lithium – oxygen electrochemical couple. The nucleation and growth of solid products during the oxygen reduction reaction, like lithium peroxide and superoxide, needs to be directed away from the electrocatalyst to prevent passivation and toward sites that facilitate product nucleation and growth. These nucleation sites must also enable electron transport to ensure oxygen evolution during charging. Model cathode surfaces can be used to explore these proximity relationships between electron transfer and product growth sites in situ using electrochemical atomic force microscopy to track solid product formation. We have developed methods for producing a variety decorated electrode substrates on which electron transfer and nucleation sites are separated and these proximity relationships can be studied as a function of the rate and extent of oxygen reduction.The impact of isolating electron transfer sites is demonstrated in the response of highly ordered pyrolytic graphite (HOPG) to ORR in a bis(trifluoromethane) sulfonamide (LiTFSI) - tetraethylene glycol dimethyl ether (TEGDME) electrolyte (Figure 1). The step edges represent line defects with a heterogeneous rate constant many orders of magnitude greater than the adjacent terraces (R. McCreery et al., Anal Chem, 2012). Driving the ORR at relatively slow rates (ca. μA/cm2) results in initial nucleation and growth of particles along these defects with the eventual formation of large particles imbedded in a thin, continuous product film at the point of eventual electrode passivation, In contrast, a uniformly electroactive Au(111) surface exhibits the formation of a continuous thin film without significant particle formation. These results emphasize the fact that a significant amount of the peroxide and superoxide formed during ORR originate from precipitation reactions. The precipitation of lithium peroxide argues that disproportionation of the electrogenerated superoxide takes place in solution and not on the electrode surface. The impact of creating discrete sites for solid product nucleation and growth is explored by decorating graphite with MnO2 particles. The expectation is that an oxide surface should represent a favorable site for the nucleation and growth of the peroxide and superoxide products. β-MnO2 has been shown to exhibit enhanced activity for ORR in LiTFSI:TEGDME (O. Oloniyo et. Al., J Electronic Mater, 2012). Vacuum techniques are used to decorate HOPG with β-MnO2 nanoparticles, where the relative preference for particle growth at step edges and terraces can be controlled with the use of active oxygen. Figure 1 shows an example of directing β-MnO2 growth at the step edges. Conducting ORR on this electrode, at the same current density as for the pristine HOPG surface, shows that product formation occurs as a conformal coating over the β-MnO2nanoparticles. These results indicate that it should be possible to control the location of product nucleation.Voltammetry and chronopotentiometry show that Au(111) is considerably more active for ORR relative to either graphite step edges or β-MnO2 nanoparticles in this LiTFSI:TEGDME electrolyte. We have combined both Au and MnO2 nanoparticles onto graphite with the Au placed at step edges and the MnO2 on the terraces to achieve electron transfer and nucleation site separation. Results from ORR rate and extent studies with these structured electrodes will be presented and discussed. This work is supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE’s NNSA under contract DE-AC04-94AL85000.

Multi-Methodology Modeling and Design of Lithium-Air Cells with Aqueous Electrolyte

Metal-air batteries are being investigated as alternative to state-of-the-art lithium-ion batteries for mobile and stationary applications due to their higher specific energy and potentially lower cost. Modeling and simulation techniques allow a better understanding and improvement of the complex mechanisms and properties of metal-air batteries. Here we present combined modeling and experimental results on a lithium-air (Li/O2) battery with aqueous alkaline (LiOH) electrolyte using three different modeling methodologies, (i) Lattice-Boltzmann simulations on the porous electrode scale, (ii) multi-physics continuum modeling on the single-cell scale and (iii) system simulation of a Li/O2-operated electric vehicle.Lattice-Boltzmann simulations on experimentally reconstructed Ag-based gas diffusion electrodes (GDE) are performed in order to derive multi-phase transport parameters, in particular, saturation/pressure relationships and effective diffusion coefficients. The computational domain of the 1D continuum model consists of the gas-diffusion electrode as cathode, a porous separator, and a lithium metal anode. The model includes a detailed description of the multi-step electrochemistry including dissolution of O2into the liquid electrolyte, oxygen reduction to hydroxyl ions, and nucleation and growth of the solid reaction product LiOH [1]. The model is validated with experimental half-cell measurements over a wide range of conditions. The multi-physics model is integrated into a system simulation of a battery electric vehicle, including electric engine and regenerative braking. The model is used to simulate driving cycles (Fig. 1), which allow to quantify practical energy and power densities and to investigate the potential of lithium-air technology as next-generation battery for electromobility.As key result, the alkaline lithium-air battery offers the interesting capability of high-power cycling using only liquid-phase dissolved intermediates (O2 + 4e– + 2 H2O ⇄ 4 OH–) coupled to high-energy content due to solid product formation (Li+ + OH– + H2O ⇄ LiOH·H2O). This dual functionality can be exploited for the driving cycle using model-based cell design.[1] B. Horstmann, T. Danner, and W. G. Bessler, “Precipitation in aqueous lithium-oxygen batteries: a model-based analysis,” Energy & Environmental Science 6, 1299–1314 (2013).

The interrelationship between surface chemistry and rheology in alkali activated slag paste

Ground granulated blast furnace slag can react with an alkaline activating solution to form a cement-like binder based on a calcium–sodium aluminosilicate gel, which is a potential alternative to Portland cement in many applications. This study provides new information regarding the effect of activator type and dosage on rheology by monitoring changes in pH, particle surface charge (zeta potential), and heat evolution in the early stages of the reaction process. Sodium and potassium hydroxide silicate solutions, at two different M2O (M: Na, K) dosages, are used here as activators. Alkali hydroxide activators cause a significant increase in the yield stress of an activated slag paste, especially at higher dosages as reactions take place rapidly, while within the same timeframe, the yield stress of the silicate activated slag remains unchanged. The results imply a direct relationship between a higher reaction rate with the formation of solid products (causing both spatial blockage effects and consumption of free water), and a rapid yield stress increase. However, the dependence of reaction rate on pH for different alkali-activated pastes is, at most, indirect. All activators induce a highly alkaline pH and a concentrated electrolyte solution environment in the fluid paste. As a result of complexation of poorly-hydrated ions on the surfaces of the particles, the magnitude of the zeta potential increases. A direct relationship is observed between the dosage of the activators and zeta potential. A zeta potential further from neutrality generally reduces yield stress by increasing the magnitude of double layer repulsive forces, with the exception of a higher dosage of silicate activator, which shows an indication of some attractive double layer forces.

Production of phenols from lignin-derived slurry liquid using iron oxide catalyst

A two-step process consisting of depolymerization and catalytic cracking without hydrogen addition was carried out to produce phenols from lignin. In the first step, lignin was depolymerized using a silica-alumina catalyst in a water/1-butanol solution at 623K for 2h. After the reaction, lignin-derived slurry liquid was obtained in 67C-mol% yield. From the model studies, it was considered that lignin was mainly depolymerized via hydrolysis of aryl ether bonds between lignin units. For the second step, the catalytic reaction of the 1-butanol phase of the slurry liquid was carried out over an iron oxide catalyst using a high pressure fixed-bed flow reactor at 673K. The catalytic reaction under high pressure steam conditions was effective for the suppression of the formation of solid products. In addition, the recovery fraction of phenols increased as the FH2O/F value (the flow rate ratio of steam to the slurry liquid) increased, resulting in 17% of phenols at FH2O/F=5 for 2–4h. From the model studies and our previous results, catechol and methoxyphenol in the slurry liquid were considered to be converted into phenols, cresols and other alkyl phenols over the iron oxide catalyst.

The pyrolysis chemistry of a β-O-4 type oligomeric lignin model compound

The pyrolysis behavior of a β-O-4 type oligomeric lignin model compound is studied at a temperature range from 250 °C to 550 °C. Thermogravimetric analysis (TGA) indicates the model compound has three distinct thermal decompositions peaks when a slow temperature ramp is applied while only one decomposition peak is observed when a higher temperature ramp is used. The pyrolysis behavior of this model compound is similar to that of lignin prepared by enzymatic hydrolysis of Maplewood. 1H-NMR shows that the β-O-4 linkage thermally decomposes at a temperature between 250 °C and 350 °C with the formation of solid products at 350 °C. This solid product undergoes transformation to a polyaromatic from 350 °C to 550 °C. Around twenty five volatile compounds are quantified by pyroprobe-GC-MS with vanillin and 2-methoxy-4-methyl phenol being the most abundant monomeric products. A free radical reaction pathway is proposed to explain the product chemistry for pyrolysis of the lignin model compound. Char is most likely formed by random repolymerization of the radicals.