Lignin Gasification Research Articles

Catalytic ethanolysis and gasification of kraft lignin into aromatic alcohols and H2-rich gas over Rh supported on La2O3/CeO2–ZrO2

Efficient catalytic ethanolysis and gasification of kraft lignin were conducted over a versatile supported catalyst Rh/La2O3/CeO2–ZrO2 to give high-value aromatic alcohols and H2-rich gas. The removal of phenolic hydroxyl group was the most prevalent reaction, and importantly, almost no phenols, undesired char and saturating the aromatic ring were detected. Meanwhile, the feedstock and solvent both played key roles in H2 generation that contributed to the hydrodeoxygenation of liquid components and made the whole catalytic process out of H2 supply. Reusability tests of catalyst indicated that the crystalline phase transition and agglomeration of support, the loss of noble metal Rh and carbon deposition were the possible reasons for its deactivation in supercritical ethanol. Comparing with water, methanol and isopropanol system, ethanol was the only effective solvent for the depolymerization process.

Hydrocarbon bio-jet fuel from bioconversion of poplar biomass: techno-economic assessment.

BackgroundInfrastructure compatible hydrocarbon biofuel proposed to qualify as renewable transportation fuel under the U.S. Energy Independence and Security Act of 2007 and Renewable Fuel Standard (RFS2) is evaluated. The process uses a hybrid poplar feedstock, which undergoes dilute acid pretreatment and enzymatic hydrolysis. Sugars are fermented to acetic acid, which undergoes conversion to ethyl acetate, ethanol, ethylene, and finally a saturated hydrocarbon end product. An unfermentable lignin stream may be burned for steam and electricity production, or gasified to produce hydrogen. During biofuel production, hydrogen gas is required and may be obtained by various methods including lignin gasification.ResultsBoth technical and economic aspects of the biorefinery are analyzed, with different hydrogen sources considered including steam reforming of natural gas and gasification of lignin. Cash operating costs for jet fuel production are estimated to range from 0.67 to 0.86 USD L−1 depending on facility capacity. Minimum fuel selling prices with a 15 % discount rate are estimated to range from 1.14 to 1.79 USD L−1. Capacities of 76, 190, and 380 million liters of jet fuel per year are investigated. Capital investments range from 356 to 1026 million USD.ConclusionsA unique biorefinery is explored to produce a hydrocarbon biofuel with a high yield from bone dry wood of 330 L t−1. This yield is achieved chiefly due to the use of acetogenic bacteria that do not produce carbon dioxide as a co-product during fermentation. Capital investment is significant in the biorefinery in part because hydrogen is required to produce a fully de-oxygenated fuel. Minimum selling price to achieve reasonable returns on investment is sensitive to capital financing options because of high capital costs. Various strategies, such as producing alternative, intermediate products, are investigated with the intent to reduce risk in building the proposed facility. It appears that producing and selling these intermediates may be more profitable than converting all the biomass into aviation fuel. With variability in historical petroleum prices and environmental subsidies, a high internal rate of return would be required to attract investors.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0545-7) contains supplementary material, which is available to authorized users.

Enhanced biofuel processes utilizing separate lignin and carbohydrate processing of lignocellulose

ABSTRACTEnhanced biofuel production routes utilizing separate lignin and carbohydrate processing of lignocellulose are analyzed and compared with two conventional routes; the methanol and methane production via syngas from biomass. The enhanced processes studied are: hydrocarbons production by hydrogenation of biomass based sugars by hydrogen obtained from lignin gasification, and ethanol production by biomass hydrolysis and fermentation and conversion of residual lignin into methanol via syngas. The analysis of processes was done by rigorous flowsheet modeling including power production calculations and realistic heat integration and evaluation based on energy yield, greenhouse gas (GHG) reduction and net present value (NPV). The enhanced processes via separate lignin and sugar processing can run in two modes: either being energy self-sufficient or utilizing external low temperature heat and power. The processes can operate with high efficiency as ‘waste heat and power to gas and liquids’ processes for producing liquid or gaseous fuels especially when excess energy is available e.g. in summer. Of all the processes studied the enhanced hydrocarbon production process integrated with external low temperature heat source gave the largest GHG reduction and highest NPV. External low temperature heat and electricity is converted into fuels in 136% higher heating value (116% lower heating value) efficiency.

Study on the catalytic gasification of alkali lignin over Ru/C nanotubes in supercritical water

Aiming at the degradation-resistant characteristic of alkali lignin, gasification of alkali lignin in supercritical water was carried out in a batch reactor with Ru/C nanotubes as catalyst. The effects of temperature, water density, time, reactant concentration, catalyst amount as well as the catalytic efficiency on the gasification of alkali lignin were examined. The optimum conditions obtained with single factor analysis are as follows: reaction temperature 600°C, water density 0.1284 g/cm3, reaction time 60 min, reactant concentration 3.0%, and catalyst amount of 0.5 (g/g alkali lignin). The results show that high temperature, high water density (or pressure), long reaction time, low reactant concentration and moderate amount of catalyst will be in favor of the gasification of alkali lignin in supercritical water. The alkali lignin gasification efficiency and carbon conversion reaches 73.74% and 56.34%, respectively, under the optimal reaction conditions. Hydrogen production capacity is also significantly improved.

Systematic screening and modification of Ni based catalysts for hydrogen generation from supercritical water gasification of lignin

In this study, systematic screening of 29 catalysts synthesised using five supports: Al2O3, activated carbon (AC), TiO2, ZrO2, MgO, and three promoters: Co, Cu, Ce (with two different Ce precursors) was performed. Then, the optimization of the Ni–Ce/Al2O3 catalyst was carried out by varying Ni loading (four levels) and Ce/Ni molar ratio (two levels). All these catalysts were screened for supercritical water gasification (SCWG) of lignin under the operating conditions of 650°C, 26MPa and water to biomass mass ratio of 5 in a tubular batch reactor. Various characterization techniques were used to investigate the properties of these catalysts further. As the result, using different supports, the activity of Ni-based catalysts for SCWG of lignin was found in the order of Al2O3>TiO2>AC>ZrO2>MgO. As the best promoter, Ce enhanced the hydrogen selectivity by promoting the Ni dispersion and weakening the Ni–Al2O3 interaction. Use of different precursors for the Ce promoter (CeCl3·6H2O or Ce(NO3)3·6H2O) showed no effect on the hydrogen yield. For a fixed Ni loading, hydrogen yield increased with an increase in Ce/Ni molar ratio. The 20Ni–0.36Ce/Al2O3 catalyst showed highest hydrogen yield of 2.15mmol/g, which is 35% higher than that for non-catalytic run. The better performance of Ni–Ce/Al2O3 catalyst can be attributed to enhanced coke resistance as well as increased reducibility for Ni by addition of Ce promoter.

Noncatalytic Gasification of Lignin in Supercritical Water Using a Batch Reactor for Hydrogen Production: An Experimental and Modeling Study

In this work, Central Composite Design (CCD) methodology was first introduced to noncatalytic SCWG of lignin for experimental design, model building, and data analysis. Noncatalytic SCWG of lignin was performed in a batch reactor with the specific focus on hydrogen yield optimization. By both experimental and statistical modeling, the main effects as well as interaction effects of three parameters including temperature, pressure, and water to biomass ratio were investigated in a wide range of 399–651 °C, 23–29 MPa, 3–8, respectively. As the result, up to 651 °C higher temperature is desirable for hydrogen production; however, change of pressure from 23–29 MPa did not show significant effect on hydrogen yield. Strong interaction between temperature and water to biomass ratio was observed at temperatures higher than 525 °C, and a dramatic decrease in hydrogen yield with increase in water to biomass ratio was observed at 600 °C. According to the model, the maximum hydrogen yield can reach 1.60 mmol/g biomass...

Catalytic gasification of lignin with Ni/Al2O3–SiO2 in sub/supercritical water

Lignin has been gasified with a Ni/Al2O3–SiO2 catalyst in sub/supercritical water (SCW) to produce gaseous fuels. XRD pattern at 6θ angle shows characteristic peaks of crystalline NiO, NiSi, and AlNi3, suggesting that Al2O3–SiO2 not only offers high surface area (122m2g) for Ni, but also changes the crystal morphology of the metal. 9mmol/g of H2 and 3.5mmol/g of CH4 were produced at the conditions that 5.0wt% alkaline lignin plus 1g/g Ni/Al2O3–SiO2 operating for 30min at 550°C. A kinetic model was also developed, and the activation energies of gas and char formation were calculated to be 36.68±0.22 and 9.0±2.4kJ/mol, respectively. Although the loss of activity surface area during reuse caused slight activity reduction in Ni/Al2O3–SiO2, the catalyst system still possessed high catalytic activity in generating H2 and CH4. It is noted that sulfur linkage could be hydrolyzed to hydrogen sulfide in the gasification process of alkaline lignin. The stable chemical states of Ni/Al2O3–SiO2 grants its insensitivity to sulfur, suggesting that Ni/Al2O3–SiO2 should be economically promising for sub/supercritical water gasification of biomass in the presence of sulfur.

Effects of experimental conditions and of addition of natural minerals on syngas production from lignin by oxy-gasification: Comparison of bench- and pilot scale gasification

Gasification of spent lignin pellets was used to obtain a gas suitable for energy production. Spent lignin was obtained from second-generation cellulosic ethanol demo plant using wheat straw as feedstock. Gasification of lignin did not give rise to any feeding problems, thus no significant changes were needed in the existing gasification installation. The rise of temperature and steam flow rate favoured the formation of H2, while hydrocarbons (CnHm) and tar contents decreased. The increase of equivalent ratio (ER) also decreased hydrocarbons and tar contents, but syngas higher heating value (HHV) was reduced. The use of natural minerals improved lignin gasification. The presence of dolomite led to the highest H2 and to the lowest CnHm and tar contents. Results obtained at bench-scale were confirmed at pilot-scale, as similar trends were obtained. However, as the residence time in pilot gasifier was higher, greater gas yields with higher H2 and CH4 concentrations were obtained, while tar contents decreased. After syngas hot cleaning and upgrading, the final syngas composition showed to be suitable for a wide range of applications (e.g. energy production and synthesis of chemicals), since it was substantially enriched in hydrogen, whereas tar and heavier gaseous hydrocarbons were completely destroyed.

Synthesis Gas Production via Non-catalytic and Catalytic Gasification of Lignin with High-moisture Content

)) for a feedstock of liquid fuel synthesis as an alternative to the petrol and diesel oil, and for hydrogen source applied to a fuel of fuel cells. With increasing moisture content, the gasification of the wet biomass produces less char and tar, whereas more input enthalpy of water is required to achieve reaction temperature (750-950℃). Based on the features, the optimum moisture content of the biomass exists. The optimum moisture content and reaction temperature were investigated for effective production of synthesis gas. From the typical results of gasification of the lignin slurry in fixed-bed downdraft type gasifier, conversion-to-gas ranged from 45.5 to 78.4 C-mol%, while char yield ranged from 11.2 to 55.1 C-mol%. The cold-gas efficiency varied from 71.9 to 95.6% for moisture content of 73-90 wt.%. For the results of a catalyst (NiO/CaO-Al

Catalytic Gasification of Lignin in Supercritical Water

Lignin was gasified in supercritical water (SCW) with Ru/C, Pt/C, Pd/C and Ni/Al2O3-SiO2. The results indicated that the gasification yield (GY) and carbon yield (CY) were dramatically improved by four nano noble metal catalysts, especially with Ru/C, which doubled the GY and CY. The reason might be that catalysts can reduce lignin and help opening-ring, which lead to efficient gasification of lignin in SCW, but further research is necessary. Four catalysts have some different selectivity to different gases, but gaseous compositions are still similar as catalysis can’t change the reactions equilibrium.

Characteristics of tar formation during cellulose, hemicellulose and lignin gasification

This study compares the major biomass components (i.e., cellulose, hemicellulose and lignin) with respect to their differing tar formation characteristics during the gasification process. To better understand the tar formation mechanism, the tar content and composition were analysed via gas chromatography coupled with mass spectrometry (GC–MS). The tar yields of the three components all decreased with increasing temperature or excess air ratio (ER). However, lignin has a higher tar yield and produces more stable components in tar due to its molecular structure. At higher temperatures, the tar composition shifts toward higher-molecular-weight substances, such as polycyclic aromatic hydrocarbons (PAHs). For lignin, PAHs are derived primarily from phenols and its derivatives. For cellulose and hemicellulose, PAHs are derived primarily from benzene, toluene, ethylbenzene and xylene isomers (BTEX) and miscellaneous hydrocarbons. During the gasification process of real biomass materials, it is crucial to remove the tar compounds derived from lignin for tar control.

Supercritical Water Gasification of Organosolv Lignin over a Graphite-supported Ruthenium Metal Catalyst

Abstract A graphite-supported ruthenium metal catalyst was highly active for catalytic gasification of organosolv lignin in supercritical water at 673 K because of the easy accessibility of the reaction intermediates to ruthenium metal sites on the graphite surface, compared to a charcoal-supported ruthenium metal catalyst.

Gasification of Organosolv-lignin Over Charcoal Supported Noble Metal Salt Catalysts in Supercritical Water

Charcoal supported metal salt catalysts showed activities for the lignin gasification at 673 K, especially the catalysts without chloride anion showed the complete gasification. The order of activity for the gasification among the metal species was following: ruthenium > rhodium > platinum > palladium ~ nickel. X-ray absorption fine structure analysis revealed that small metal particles were formed on the charcoal support after the gasification for the supported ruthenium, rhodium, and platinum salt catalysts without chloride anion; on the other hand, larger metal particles were formed in the presence of chloride anion. Lower activities and deactivation for supported metal salt catalysts having the chloride anion were caused by poisoning by chloride anions and the smaller number of metal sites.

Conversion Synergies during Steam Co-Gasification of Ligno-Cellulosic Simulated Biomass with Coal

Lignin and cellulose chemicals were used as artificial biomass components to make-up a simulated biomass. Alkali and Alkaline Earth Metal (AAEM) as well as volatile matter contents in these chemicals were much different from each other. Co-gasification of coal with simulated biomass shows improved conversion characteristics in comparison to the average calculated from separate conversion of coal and simulated biomass. Two conversion synergetic peaks were observed whereby the first peak occurred around 400℃ while the second one occurred above 800℃. Although co-gasification of coal with lignin that has high AAEM content also shows two synergy peaks, the one at higher temperature is dominant. Co-gasification of coal with cellulose shows only a single synergy peak around 400℃ indicating that synergy at low temperature is related with interaction of volatiles. Investigation of morphology changes during gasification of lignin and coal, suggests that their low reactivity is associated with their solid shape maintained even at high temperature.

Lignin Gasification over Charcoal-supported Palladium and Nickel Bimetal Catalysts in Supercritical Water

Abstract Charcoal-supported palladium and nickel binary salt catalysts showed higher lignin gasification activity than the linear combination activities of the individual monometal catalysts, indicating a bimetallic synergetic effect. XRD and EXAFS analyses revealed that Pd–Ni alloy structures were formed during the lignin gasification over the catalysts, which provided higher activities for the gasification than the individual monometal catalysts.

Kinetic model for noncatalytic supercritical water gasification of cellulose and lignin

AbstractThis article reports the first kinetics model for Supercritical Water Gasification (SCWG) that describes the formation and interconversion of individual gaseous species. The model comprises 11 reactions, and it uses a lumping scheme to handle the large number of intermediate compounds. We determined numerical values for the rate constants in the model by fitting it to experimental data previously reported for SCWG of cellulose and lignin. We validated the model by showing that it accurately predicts gas yields at biomass loadings and water densities not used in the parameter estimation. Sensitivity analysis and reaction rate analysis indicate that steam‐reforming and water–gas shift are the main sources of H2 in SCWG, and intermediate species are the main sources of CO, CO2, and CH4. © 2010 American Institute of Chemical Engineers AIChE J, 2010

Production of hydrogen by steam gasification from lignin with Al 2O 3·Na 2O· xH 2O/NaOH/Al(OH) 3 catalyst

Some influencing factors on hydrogen production from steam gasification of lignin with Al 2O 3·Na 2O· xH 2O/NaOH/Al(OH) 3 catalyst in a fixed bed reactor were examined. The results show that the formation rates of hydrogen increase with increasing ratio of Na 2O/C and ratio of vapor to lignin as a whole. Higher flow rate of vapor is conducive to inhibit the generation of CO and CO 2 at lower temperature. H 2O(g) produced by the hydrates contained in the catalyst can bring on more Na + and OH − ions to be formed by dissociation of NaOH within the catalyst. This leads to more remarkable reduction of the C—H bond energies of lignin. The conversion degree of hydrogen of lignin at 473–973 K reaches 134.94%, which shows that the present catalyst has good catalytic activity on hydrogen production from steam gasification of lignin at low temperature.

Effect of Metals on Supercritical Water Gasification of Cellulose and Lignin

We gasified cellulose and lignin in supercritical water, using quartz reactors, and quantified the catalytic effect of metals by adding them to these reactors in different forms. We used nickel, iron, copper, zinc, and zirconium wires, ruthenium powder, and Raney nickel slurry. The presence of metals was more likely to increase gas yields to a measurable extent when the catalyst surface area/biomass weight ratio was at least 15 mm2/mg (5.0 wt % biomass loading in our experiments). Nickel and copper typically provided higher gas yields at 5.0 wt % loading, and nickel provided the highest H2 yields at 1.0 wt % loading. SCWG at 500 °C with nickel at 240 mm2/mg generated 16 mmol/g of H2 from cellulose. CH4 yields were not strongly influenced by the presence of metals. With nickel wires in the reactor, gas with about 40−50% of the energy content in the original biomass was produced from cellulose and lignin. All of the metals tested except copper produced H2 from water when exposed to SCWG conditions with no biomass. It is important that this background H2 formation be accounted for when interpreting results from SCWG experiments in the presence of metals. Exposure of nickel wires to supercritical water did not reduce their activity for H2 production.

Expanded and Updated Results for Supercritical Water Gasification of Cellulose and Lignin in Metal-Free Reactors

We report updated and expanded results from a systematic study of the effects of process variables on the gasification of cellulose and lignin in supercritical water in quartz reactors. Quartz reactors eliminate potential catalytic effects from metallic walls. The gases produced were far from their equilibrium composition. High temperatures, high water densities, and long reaction times provide the highest H2 yields. The total gas yields and energy content of the gas were largely insensitive to the water density and biomass loading, with lignin gasification at 1.0 wt % loading being the exception. The yields of CO2, CH4, and H2 displayed an Arrhenius-like dependence on temperature. The apparent activation energies for CO2 and H2 production were about 15 and about 60 kJ/mol, respectively, and this difference suggests that these products did not primarily form together in a common reaction pathway. The activation energies for each of the product gases, however, were about the same for both cellulose and lig...

Simulation of Fuel Ethanol Production from Lignocellulosic Biomass

Models for hydrolysis, fermentation and concentration process, production and utilization of biogas as well as lignin gasification are developed to calculate the heat demand of ethanol production process and the amounts of heat and power generated from residues and wastewater of the process. For the energy analysis, all relevant information about the process streams, physical properties, and mass and energy balances are considered. Energy integration is investigated for establishing a network of facilities for heat and power generation from wastewater and residues treatment aiming at the increase of energy efficiency. Feeding the lignin to an IGCC process, the electric efficiency is increased by 4.4% compared with combustion, which leads to an overall energy efficiency of 53.8%. A detailed sensitivity analysis on energy efficiency is also carried out.