Upgrading Of Biomass Pyrolysis Vapors Research Articles

Catalytic upgrading of biomass pyrolysis vapors for selective production of phenolic monomers over metal oxide modified alumina catalysts

This study investigates the catalytic vapor phase upgrading of sawdust to produce improved biocrude enriched in phenolic monomers. Various mixed metal oxide catalysts (MgO, CuO, Bi2O3, NiO, ZnO supported on Al2O3) were screened to determine the product composition. Further, the effect of different process parameters such as temperature (350 – 600 °C), metal oxide loadings (0 – 20 wt%), catalyst to biomass ratios (1:1–1:6), sweeping gas flow rates (0 – 15 LPH) were studied in terms of biocrude composition. Under non-catalytic conditions, maximum biocrude yields (∼39%) were obtained at an optimum temperature of 550 °C. The biocrude composition varied significantly with the type of metal oxide in which MgO and CuO produced higher amounts of phenolics (∼58%). Increasing MgO loading (5–20 wt%) and higher catalyst to biomass ratios (1:1) resulted in enhanced hydrocarbon yields to ∼15%. Premixing of biomass and catalyst in a fixed bed arrangement resulted in enhanced hydrocarbons/aromatics with simultaneous reduction in the phenolic content.

Enhanced activity of NiZrBEA catalyst for upgrading of biomass pyrolysis vapors to H2-rich gas

The main objective of these studies was development of competitive catalyst for the upgrading of biomass pyrolysis vapors to H2-rich gas. The performed experiments were devoted to determination of the effect of incorporation of zirconium into the structure of BEA zeolite on the performance of NiBEA in the mentioned process. Moreover, the most important parameters responsible for the increased activity of NiZrBEA catalyst in comparison to nickel supported on parent zeolite have been identified. The activity of synthesized catalysts was tested in two step fixed bed quartz reactor. Firstly, cellulose or pine were heated to the 500 °C in order to decompose lignocellulosic feedstock. Then, formed pyrolysis vapors were directed through catalyst bed (700 °C) where their upgrading took place. The obtained results revealed that an introduction of zirconium in the structure of BEA zeolite allowed for the increase in the efficiency of Ni catalyst in the formation of H2-rich gas. It was related to the increase in pore volume of the synthesized materials, formation of smaller nickel oxide crystallites and creation of the catalysts with moderate acidity.

Mild upgrading of biomass pyrolysis vapors via ex-situ catalytic pyrolysis over an iron-montmorillonite catalyst

Pyrolysis vapor upgrading can improve the stability of pyrolysis liquids to facilitate storage, transport, and drop in use as fuels and chemical feedstocks in existing refining infrastructure. This study investigates a low cost iron based catalyst for mild in-situ upgrading of fast pyrolysis vapors to increase the stability of pyrolysis liquid. Iron-doped montmorillonite K10 catalysts were characterized by ICP-OES, BET porosimetry, XRD, XPS, and NH3-TPD. The effect of three upgrading process parameters are evaluated by Box-Behnken experimental design using a fixed catalyst bed. Predictive model equations are developed based on response surface methodology to describe the effect of iron loading, catalyst to biomass ratio, and catalyst bed temperature on yields of pyrolysis liquids, non-condensable gas, and coke on the catalyst. Compared to non-catalytic pyrolysis, pyrolysis vapor upgrading over iron catalyst reduce pyrolysis liquid yields and increase gas yields as pyrolysis vapors are catalytically cracked into lighter molecules. Liquid yield decreases with C:B ratio while gas yields increase. By increasing Fe loading from 0% to 10%, catalyst coking decreases from 11.7% to 3.5% yield. Iron loading of 10% is the least susceptible to coking, but results in greater amounts of polyaromatics in the pyrolysis liquid product. According to GCMS analysis of the pyrolysis liquids, upgraded pyrolysis liquids have lower concentrations of unstable carboxylic acids and aldehydes. In addition, formation of phenols shift towards a greater fraction of alkyl phenols and lower fraction of methoxy phenols leading to a more stable liquid product as a result of upgrading. Overall, iron-doped montmorillonite catalyst is demonstrated to be a viable, low cost catalyst for mild upgrading of fast pyrolysis vapors.

Hydrogen-Rich Gas Production by Upgrading of Biomass Pyrolysis Vapors over NiBEA Catalyst: Impact of Dealumination and Preparation Method

The main goal of this work was to develop a highly active catalyst in lignocellulosic biomass conversion to hydrogen-rich gas. The studies were focused on the evaluation of an impact of dealuminati...

Efficient ex-situ catalytic upgrading of biomass pyrolysis vapors to produce methylfurans and phenol over bio-based activated carbon

Analytical pyrolysis-comprehensive two-dimensional gas chromatography/mass spectrometry (Py-GC × GC/MS) was used for the on-line analysis of pyrolysis vapors. Bio-based activated carbon (B-AC) catalysts were used to produce highly selectivity valuable chemicals such as furans and phenols. B-AC catalyst was subjected to several characterizations to investigate the physicochemical properties of the catalyst and its relationship with products distribution. The results showed that B-AC catalyst showed high catalytic activity and selectivity for the production of furans and phenols under mild catalytic temperature (350 °C). Furans are mainly from pyrolysis of cellulose and hemicellulose, while phenols are mainly from pyrolysis of lignin. Methylfurans and phenol were dominated compounds. With the use of B-AC, the relative peak area of methylfurans increased from 6.58% to 39.35% (cellulose), 0%–27.79% (xylan), 0.54%–26.82% (corncob); the relative peak area of phenol increased from 6.31% to 53.83% (lignin) and 2.77%–12.34% (corncob). A significant reduction of aldehydes, ketones, and sugars was also observed over B-AC catalyst. The higher total acidity (weak acidity and Lewis acidity) of B-AC favored the formation of 2-methylfuran and phenol.

Catalytic upgrading of biomass-derived pyrolysis vapour over metal-modified HZSM-5 into BTX: a comprehensive review

This paper provides an updated and comprehensive review on the catalytic upgrading of biomass-derived pyrolysis vapours over metal-modified HZSM-5 catalyst into bio-aromatic hydrocarbons. The catalytic upgrading of biomass pyrolysis vapours seems to be a promising technology in generating gasoline-type bio-aromatic hydrocarbons, i.e. benzene, toluene and xylene (BTX). Biomass-derived raw pyrolysis oil has high oxygenated compounds that deteriorate pyrolysis oil properties and limits its applications. Metal modification of hydrogen exchanged Zeolite Socony Mobil Five (HZSM-5) catalyst has gained attention in a biomass pyrolysis research area due to the beneficial effects on upgrading the oxygenated pyrolysis vapours into BTX-enriched pyrolysis oils. The influence of metals (alkali and alkaline earth metals, transition metals and rare earth metals) as bi-functional or multifunctional activity on HZSM-5 catalyst during pyrolysis has been addressed. The effect of reaction temperature, the type of metals, metal contents, the silica-to-alumina ratio of catalyst and the catalyst-to-biomass ratio are critically discussed for maximum production of monocyclic aromatic hydrocarbons during the upgrading of pyrolysis vapours. Finally, concluding remarks on metal-modified zeolite catalyst and future recommendation in upgrading biomass pyrolysis vapours are presented.

Effect of H-ZSM-5 and Al-MCM-41 Proportions in Catalyst Mixtures on the Composition of Bio-Oil in Ex-Situ Catalytic Pyrolysis of Lignocellulose Biomass

The present work is an attempt to optimize the proportion of H-ZSM-5 and Al-MCM-41 in the catalyst mixtures for lignocellulose biomass catalytic pyrolysis. The H-ZSM-5 proportions of 50.0, 66.7, 75.0, and 87.5 wt.% were examined for the upgrading of biomass pyrolysis vapors in the fixed bed reactor. The catalyst mixture of 87.5 wt.% H-ZSM-5 and 12.5 wt.% Al-MCM-41 was found most effective in this study, giving a 65.75% deoxygenation degree. An organic-rich bio-oil was obtained with 74.90 wt.% of carbon content, 8 wt.% of hydrogen content, 15 wt.% oxygen content, a 0.39 wt.% water content, and a high heating value of 34.15 MJ/kg. The highest amount of desirable compounds among the studied catalytic experiments, which include hydrocarbons, phenols, furans, and alcohols, was obtained with a value of 95.89%. A significant improvement in the quality of bio-oil with the utilization of H-ZSM-5 and Al-MCM-41 catalyst mixtures was the rise of desirable compounds in bio-oil.

Counteracting Rapid Catalyst Deactivation by Concomitant Temperature Increase during Catalytic Upgrading of Biomass Pyrolysis Vapors Using Solid Acid Catalysts

The treatment of biomass-derived fast pyrolysis vapors with solid acid catalysts (in particular HZSM-5 zeolite) improves the quality of liquid bio-oils. However, due to the highly reactive nature of the oxygenates, the catalysts deactivate rapidly due to coking. Within this study, the deactivation and product yields using steam-treated phosphorus-modified HZSM-5/γ-Al2O3 and bare γ-Al2O3 was studied with analytical Py-GC. While at a fixed catalyst temperature of 450 °C, a rapid breakthrough of oxygenates was observed with increased biomass feeding, this breakthrough was delayed and slower at higher catalyst temperatures (600 °C). Nevertheless, at all (constant) temperatures, there was a continuous decrease in the yield of oxygen-free hydrocarbons with increased biomass feeding. Raising the reaction temperature during the vapor treatment could successfully compensate for the loss in activity and allowed a more stable production of oxygen-free hydrocarbons. Since more biomass could be fed over the same amount of catalyst while maintaining good deoxygenation performance, this strategy reduces the frequency of regeneration in parallel fixed bed applications and provides a more stable product yield. The approach appears particularly interesting for catalysts that are robust under hydrothermal conditions and warrants further investigations at larger scales for the collection and analysis of liquid bio-oil.

Insights into the scalability of catalytic upgrading of biomass pyrolysis vapors using micro and bench-scale reactors

Comparison of catalytic upgrading of pyrolysis vapors in microscale Py-GC and continuous bench-scale reactor provides qualitative agreement in catalyst ranking between scales.

Flow and reaction characteristics on catalytic upgrading of biomass pyrolysis vapors in novel cyclone reactors

To improve the catalytic upgrading efficiency of biomass pyrolysis vapors and reduce secondary cracking of aimed products in current conventional reactors, a novel cyclone reactor was designed for the gas (biomass pyrolysis vapors)-solid (catalysts) heterogeneous reaction. The contact effect of gas-solid two-phase could be increased in the cyclonic flow field, and the separation between the gas products and catalysts occurs while flowing down due to the centrifugal force in short residence time. The rapid separation reduces secondary cracking effectively. In this study, the catalytic upgrading of pyrolysis vapors in the cyclone reactor were investigated from the aspect of fluid dynamics, residence time distribution and catalytic reaction by CFD simulation combining with the experimental method. The results indicate that in the reaction chamber of the cyclone reactor the concentration gradient of catalysts decreases gradually while flowing down. The cyclonic flow is intensified due to the guided vanes in the middle part of the reactor, and the separation effect is improved remarkably. The effects of outlet structures were investigated based on the residence time distribution and the product selectivity, the structure of Case 2 that has a vertical catalyst outlet and a horizontal gas outlet is better. The residence time of catalysts in Case 2 is 1.0s–2.0s. And the overall mass fraction of the bio-oil is 54%.

Theoretical Determination of Size Effects in Zeolite-Catalyzed Alcohol Dehydration

In the upgrading of biomass pyrolysis vapors to hydrocarbons, dehydration accomplishes a primary objective of removing oxygen, and acidic zeolites represent promising catalysts for the dehydration reaction. Here, we utilized density functional theory calculations to estimate adsorption energetics and intrinsic kinetics of alcohol dehydration over H-ZSM-5, H-BEA, and H-AEL zeolites. The ONIOM (our Own N-layered Integrated molecular Orbital and molecular Mechanics) calculations of adsorption energies were observed to be inconsistent when benchmarked against QM (Quantum Mechanical)/Hartree–Fock and periodic boundary condition calculations. However, reaction coordinate calculations of adsorbed species and transition states were consistent across all levels considered. Comparison of ethanol, isopropanol (IPA), and tert-amyl alcohol (TAA) over these three zeolites allowed for a detailed examination of how confinement impacts on reaction mechanisms and kinetics. The TAA, seen to proceed via a carbocationic mechanism, was found to have the lowest activation barrier, followed by IPA and then ethanol, both of which dehydrate via a concerted mechanism. Barriers in H-BEA were consistently found to be lower than in H-ZSM-5 and H-AEL, attributed to late transition states and either elevated strain or inaccurately estimating long-range electrostatic interactions in H-AEL, respectively. Molecular dynamics simulations revealed that the diffusivity of these three alcohols in H-ZSM-5 were significantly overestimated by Knudsen diffusion, which will complicate experimental efforts to develop a kinetic model for catalytic fast pyrolysis.

Numerical simulation and experiment on catalytic upgrading of biomass pyrolysis vapors in V-shaped downer reactors

Catalytic upgrading of biomass pyrolysis vapors is an effective utilization technology of biomass energy. Based on the disadvantages of commonly used reactors, the V-shaped downer reactors were designed to increase gas-solid two-phase turbulent intensity, contact frequency and then increase the catalytic efficiency in short residence time. The catalytic upgrading of pyrolysis vapors in V-shaped downer reactors in terms of hydrodynamics, chemical reaction and residence time distribution were analyzed by CFD simulation and experiment. The results indicate that the solid concentration gradient decreases while flowing down. The overall mass fraction of the bio-oil vapors is around 50%. The mean residence time of catalysts in the V-shaped reactor is 2.0 s–3.0 s. The effects on product yield and residence time distribution were investigated for optimizing product selectivity and the performance of catalysts. In this paper the optimal flow rates of gas and catalysts are vg = 1.2 m s−1, vs = 0.4 m s−1.

Overview of catalytic upgrading of biomass pyrolysis vapors toward the production of fuels and high‐value chemicals

The application of heterogeneous catalysis in biomass pyrolysis is considered as one of the most promising methods to improve bio‐oil quality by minimizing its undesirable properties (high viscosity, corrosivity, instability, etc.) and producing renewable fuels and high‐value chemicals. Catalytic fast pyrolysis (CFP) of biomass refers both to the “in situ” and “ex situ or two‐stage” upgrading. A plethora of catalytic materials have been investigated in the literature for both approaches, including conventional microporous zeolites, ordered mesoporous aluminosilicates, promoted or not with several transition metals, as well as various metal (nano)oxide catalysts with Lewis acidity. Recently, hybrid micro/mesoporous and basic materials have been also suggested exhibiting most promising results due to combined micro/mesoporosity and adequate balance of acid and basic sites. Optimum catalysts are required to retain deoxygenation, enhance yields of aromatics, and other valuable compounds (such as phenolics), while limiting coke formation. Coke formation is one of the reasons of catalyst deactivation; a very challenging issue during biomass CFP, especially using zeolites. The deactivation process is affected by many factors, including the composition of the feedstock (inorganic minerals present in the feedstock may also deposit on the catalyst), reaction conditions, and the nature/properties of the catalysts used in CFP. Precoking on the surface of zeolites or MgO deposition are among the proposed effective ways to suppress coke formation and thus, catalyst deactivation.This article is categorized under: Bioenergy > Science and Materials Energy Research & Innovation > Science and Materials Energy and Transport > Science and Materials

Catalytic upgrading of biomass pyrolysis vapors and model compounds using niobia supported Pd catalyst

This work addresses the effect of the support on the performance of Pd-based catalysts for hydrodeoxygenation of different model molecules (phenol, m-cresol, anisole, guaiacol) in the vapor phase at 573 K. The activity and the selectivity to deoxygenated products strongly depended on the support, regardless the model molecule. For HDO of phenol and m-cresol, benzene and toluene were the dominant products on niobia supported catalysts, whereas cyclohexanone and methylcyclohexanone were the main compounds formed on Pd/SiO2. For HDO of anisole, demethoxylation reaction producing benzene is favored over Pd/Nb2O5 catalyst, while demethylation is the preferred route over Pd/SiO2. Phenol and methanol were the main products observed for HDO of guaiacol over all catalysts but significant formation of benzene was detected over Pd/Nb2O5. The improved deoxygenation performance over the niobia supported catalysts is explained in terms of the oxophilic sites represented by Nb4+/Nb5+ cations. These catalysts were also tested for HDO of pine pyrolysis vapors. All three catalysts were effective for reducing the total yield of oxygenated products. The extent of deoxygenation was highest over the Pd/Nb2O5 and Pd/NbOPO4 catalysts. The effectiveness of Pd/Nb2O5 and Pd/NbOPO4 for deoxygenation of real feeds is in good agreement with the model compound results and suggests that these catalysts are promising materials for the upgrading of pyrolysis vapors to produce hydrocarbon fuels.

Numerical simulation of catalytic upgrading of biomass pyrolysis vapours in a FCC riser

Catalytic upgrading of biomass pyrolysis vapours is a potential method for the production of hydrocarbon fuel intermediates. This work attempts to study the catalytic upgrading of pyrolysis vapours in a pilot scale FCC riser in terms of hydrodynamics, residence time distribution (RTD) and chemical reactions by CFD simulation. NREL's Davison Circulating Riser (DCR) reactor was used for this investigation. CFD simulation was performed using 2-D Eulerian–Eulerian method which is computationally less demanding than the alternative Euler-Lagrangian method. First, the hydrodynamic model of the riser reactor was validated with the experimental results. A single study of time-averaged solid volume fraction and pressure drop data was used for the validation. The validated hydrodynamic model was extended to simulate hydrodynamic behaviours and catalyst RTD in the Davison Circulating Riser (DCR) reactor. Furthermore, the effects on catalyst RTD were investigated for optimising catalyst performance by varying gas and catalyst flow rates. Finally, the catalytic upgrading of pyrolysis vapours in the DCR riser was attempted for the first time by coupling CFD model with kinetics. A kinetic model for pyrolysis vapours upgrading using a lumping kinetic approach was implemented to quantify the yields of products. Five lumping components, including aromatic hydrocarbons, coke, non–condensable gas, aqueous fraction, and non–volatile heavy compounds (residue) were considered. It was found that the yield of lumping components obtained from the present kinetic model is very low. Thus, the further research needs to be carried out in the area of the kinetic model development to improve the yield prediction.

Promotion of the vapors from biomass vacuum pyrolysis for biofuels under Non-thermal Plasma Synergistic Catalysis (NPSC) system

Abstract Non-thermal Plasma Synergistic Catalysis (NPSC) was firstly proposed and employed in the upgrading of biomass pyrolysis vapors for preparation of biofuels. The effects of the three-way catalysis (non-thermal plasma, HZSM-5 body and modified components) on the bio-oil upgrading performance and catalyst stability were comprehensively investigated. Bio-oil yields continued to decrease, but the physicochemical properties were further improved. The contents and compositions of hydrocarbons in bio-oil were increased and improved to varying degrees. The introduction of non-thermal plasma technology enhanced performance of cracking and deoxygenation for whole catalytic process. Besides, anti-coking performance of Zn/HZSM-5 was enhanced to a certain extent, but the multiple interactions significantly improved the cracking performance when Ti species introduced, increased the coke content, and an “isomorphism” phenomenon for two kinds of coke was emerged. In general, obtained biofuels still belonged to the hydrogen-deficient fuel, lower (H/C) eff of the vapors limited substantial improvement of the fuel grade.

Deactivation of Multilayered MFI Nanosheet Zeolite during Upgrading of Biomass Pyrolysis Vapors

The catalytic fast pyrolysis (CFP) of biomass is a promising technology for producing renewable transportation fuels and chemicals. MFI-type catalysts have shown promise for CFP because they produce gasoline range hydrocarbons from oxygenated pyrolysis compounds; however, rapid catalyst deactivation due to coking is one of the major technical barriers inhibiting the commercialization of this technology. Coke deposited on the surface of the catalysts blocks access to active sites in the micropores leading to rapid catalyst deactivation. Our strategy is to minimize rapid catalyst deactivation by adding mesoporosity through formation of MFI nanosheet materials. The synthesized MFI nanosheet catalysts were fully characterized and evaluated for cellulose pyrolysis vapor upgrading to produce olefins and aromatic hydrocarbons. The data obtained from pyrolysis-GCMS (py-GCMS) showed that fresh MFI nanosheets produced similar aromatic hydrocarbon and olefin yields compared to those of conventional HZSM-5. However, ...

Coking characteristics and deactivation mechanism of the HZSM-5 zeolite employed in the upgrading of biomass-derived vapors

Abstract HZSM-5 zeolite was employed in the upgrading of biomass pyrolysis vapors in this study. The coking characteristics were investigated by means of TG, FT-IR, XRD, N2 adsorption–desorption, NH3-TPD, Py-IR, SEM and TEM methods. When the zeolite was used for three times about 120 min, its activity had been lost and the amount of coke was 12.15% composed of 9.90% of I type filamentous coke and 2.25% of II type graphite-like coke. The skeleton structure of zeolite was basically intact, which had not been seriously destroyed by coke. The surface area, pore volume and acidity of zeolite were all deteriorated vary degrees with the usage time. The zeolite granules became larger after deactivated, and the filamentous coke can be observed both on the surface and in the pore. The compositions of the coke precursors were analyzed by FT-IR and GC/MS. The precursors of coke deposited in the pore were mainly aromatic hydrocarbons, while the species of the precursors deposited on the outer surface was more including many long-chain saturated hydrocarbons. The deactivation of HZSM-5 zeolite began from inner, large molecular substances blocked the pores which resulted in the zeolite deactivation eventually.

Multiscale Evaluation of Catalytic Upgrading of Biomass Pyrolysis Vapors on Ni- and Ga-Modified ZSM-5

Metal-impregnated (Ni or Ga) ZSM-5 catalysts were studied for biomass pyrolysis vapor upgrading to produce hydrocarbons using three reactors constituting a 100 000× change in the amount of catalyst used in experiments. Catalysts were screened for pyrolysis vapor phase upgrading activity in two small-scale reactors: (i) a Pyroprobe with a 10 mg catalyst in a fixed bed and (ii) a fixed-bed reactor with 500 mg of catalyst. The best performing catalysts were then validated with a larger scale fluidized-bed reactor (using ∼1 kg of catalyst) that produced measurable quantities of bio-oil for analysis and evaluation of mass balances. Despite some inherent differences across the reactor systems (such as residence time, reactor type, analytical techniques, mode of catalyst and biomass feed) there was good agreement of reaction results for production of aromatic hydrocarbons, light gases, and coke deposition. Relative to ZSM-5, Ni or Ga addition to ZSM-5 increased production of fully deoxygenated aromatic hydrocarb...

Ex situ thermo-catalytic upgrading of biomass pyrolysis vapors using a traveling wave microwave reactor

Microwave heating offers a number of advantages over conventional heating methods, such as, rapid and volumetric heating, precise temperature control, energy efficiency and lower temperature gradient. In this article we demonstrate the use of 2450MHz microwave traveling wave reactor to heat the catalyst bed for thermo-catalytic upgrading of pyrolysis vapors. HZSM-5 catalyst was tested at three different temperatures (290°, 330° and 370°C) at a catalyst to biomass ratio of 2. Results were compared with conventional heating and induction heating method of catalyst bed. The yields of aromatic compounds and coke deposition were dependent on temperature and method of heating. Microwave heating yielded higher aromatic compounds and lower coke deposition. Microwave heating was also energy efficient compared to conventional reactors. The rate of catalyst deterioration was lower for catalyst heated in microwave system.