Effects of cellulose-lignin interaction on the evolution of biomass pyrolysis bio-oil heavy components (original) (raw)
Related papers
Journal of Analytical and Applied Pyrolysis, 2014
In this study, thermogravimetric (TG) analyses, along with thermal and catalytic fast pyrolysis experiments of cellulose, hemicellulose, lignin and their mixtures were carried out in order to investigate their pyrolysis products and whether the prediction of the pyrolysis behavior of a certain lignocellulosic biomass feedstock is possible, when its content in these three constituents is known. We were able to accurately predict the final solid residue of mixed component samples in the TG analyses but the differential thermogravimetric (DTG) curves indicated limited heat transfer when more than one component was present in the pyrolyzed sample. The limited heat transfer did not have a significant effect on the TG curves but it affected the product distribution in the fast pyrolysis experiments, which resulted in inaccurate calculation of the product yields, when using a simple additive law. In addition, the pyrolysis products of each biomass constituent were characterized in order to study their contribution to the yield and composition of the products from whole biomass pyrolysis. An investigation into the pyrolysis reaction pathways of each component was also carried out, using the bio-oil characterization data from this study and data found in the literature. pathways alternative and renewable energy source that can be converted via the biomass fast pyrolysis process into a liquid product, known as bio-oil, which is considered to be a promising biofuel/bioenergy carrier. The bio-oil is a complex mixture of oxygenated compounds and its composition and quality is heavily dependent on the composition of the biomass feedstock. Lignocellulosic biomass is composed mainly of three basic structural components; cellulose, hemicellulose and lignin. The content of these components in biomass varies depending on the biomass type. Woody plant species have tightly bound fibers and are richer in lignin while herbaceous plants have more loosely bound fibers, a fact that indicates lower lignin content. Usually, cellulose, hemicellulose and lignin constitute 40-50 wt.%, 20-40 wt.% and 10-40 wt.% of the plant material respectively . In addition to these components, lignocellulosic biomass also contains a small amount of inorganic material (ash) and extractives.
Bio-oil is a major product of biomass pyrolysis that could potentially be used in motor engines, boilers, furnaces and turbines for heat and power. Upon catalytic upgrading, bio-oils can be used as transportation fuels due to enhancement of their fuel properties. In this study, bio-oils produced from lignocellulosic biomasses such as wheat straw, timothy grass and pinewood were estimated through slow and high heating rate pyrolysis at 450 °C. The slow heating rate (2 °C/min) pyrolysis resulted in low bio-oil yields and high amount of biochars, whereas the high heating rate (450 °C/min) pyrolysis produced significant amount of bio-oils with reduced biochar yields. The physico-chemical and compositional analyses of bio-oils were achieved through carbon-hydrogen-nitrogen-sulfur (CHNS) studies, calorific value, Fourier transform-infra red (FT-IR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The yields of bio-oils produced from the three biomasses were 40-48 wt.% through high heating rate pyrolysis and 18-24 wt.% through slow heating rate pyrolysis. The chemical components identified in bio-oils were classified into five major groups such as organic acids, aldehydes, ketones, alcohols and phenols. The percent intensities of hydrogen and carbon containing species were calculated from 1 H and 13 C-NMR. The study on bio-oils from herbaceous and woody biomasses revealed their potentials for fossil fuel substitution and bio-chemical production.
Energy & Fuels, 2014
ABSTRACT This work presents three kinetic models based on a lumping approach to describe the microwave pyrolysis of kraft lignin. The first model considered the formation of the main pyrolysis products, condensable gas, non-condensable gas, and remaining solid, taking into consideration each as an individual lump. The second model investigated the liquid product while dividing the condensable gas into oil and water products. The oil product contains only chemicals, whereas the water product does not contain any chemicals. In the third model, the oil product was separated into four main groups: (1) phenolics, which contain all of the identified phenolic components using a gas chromatography mass spectrometry (GC MS) analyzer, (2) heavy-molecular-weight components, which contain all of the identified heavy-molecular-weight and undefined components, using GC MS, (3) non-phenolic aromatics with a single ring, and (4) aliphatics. The comparison of the predicted results using the estimated kinetic parameters to the experimental data showed the high capability of the presented models to estimate the product yield under the selected conditions.
The conversion of biomass by thermochemical means is very promising for the substitution of fossil materials in many energy applications. Given the complexity of biomass the main challenge in its use is to obtain products with high yield and purity. For a better understanding of biomass thermochemical conversion, many authors have studied in TG analyzer or at bed scale the individual pyrolysis of its main constituents (i.e. cellulose, hemicelluloses and lignin). Based on these studies, this original work synthesizes the main steps of conversion and the composition of the products obtained from each constituent. Pyrolysis conversion can be described as the superposition of three main pathways (char formation, depolymerization and fragmentation) and secondary reactions. Lignin, which is composed of many benzene rings, gives the highest char yield and its depolymerization leads to various phenols. The depolymerization of the polysaccharides is a source of anhydro-saccharides and furan compounds. The fragmentation of the different constituents and the secondary reactions produce CO, CO 2 and small chain compounds. For temperature higher than 500 1C, the residues obtained from the different constituents present a similar structure, which evolves towards a more condensed polyaromatic form by releasing CH 4 , CO and H 2. As the aromatic rings and their substituent composition have a critical influence on the reactivity of pyrolysis products, a particular attention has been given to their formation. Some mechanisms are proposed to explain the formation of the main products. From the results of this study it is possible to predict the reactivity and energy content of the pyrolysis products and evaluate their potential use as biofuels in renewable applications.
Thermogravimetry-FTIR Analysis of Pyrolysis of Pyrolytic Lignin Extracted from Bio-Oil
Chemical Engineering & Technology, 2012
Pyrolytic lignin is attributed to the instability of bio-oil but is a potential chemical material. To improve the stability and increase the economic viability of biooil, high-and low-molecular-mass pyrolytic lignin (HMM and LMM) were obtained using solvent extraction. The microstructure of pyrolytic lignin was examined by Fourier transform infrared spectrometry (FTIR). The dissimilar absorption intensities indicated the different content of corresponding functional groups in HMM and LMM. The pyrolysis behavior of HMM and LMM was studied by thermogravimetry coupled with FTIR. Obviously pyrolytic lignin undergoes three weight loss stages.
The effect of lignin and inorganic species in biomass on pyrolysis oil yields, quality and stability
Fuel, 2008
This paper investigates four reference fuels and three low lignin Lolium Festuca grasses which were subjected to pyrolysis to produce pyrolysis oils. The oils were analysed to determine their quality and stability, enabling the identification of feedstock traits which affect oil stability. Two washed feedstocks were also subjected to pyrolysis to investigate whether washing can enhance pyrolysis oil quality. It was found that the mineral matter had the dominate effect on pyrolysis in compared to lignin content, in terms of pyrolysis yields for organics, char and gases. However the higher molecular weight compounds present in the pyrolysis oil are due to the lignin derived compounds as determined by results of GPC and liquid-GC/MS. The light organic fraction also increased in yield, but reduced in water content as metals increased at the expense of the lignin content. It was found that the fresh oil and aged oil had different compound intensities/concentrations, which is due to a large number of reactions occurring when the oil is aged day by day. These findings agree with previous reports which suggest that a large amount of re-polymerisation occurs as levoglucosan yields increase during the aging progress, while hydroxyacetaldehyde decrease. In summary the paper reports a window for producing a more stable pyrolysis oil by the use of energy crops, and also show that washing of biomass can improve oil quality and stability for high ash feedstocks, but less so for the energy crops.
Bio-oil from fast pyrolysis of lignin: Effects of process and upgrading parameters
Bioresource technology, 2017
Effects of process parameters on the yield and chemical profile of bio-oil from fast pyrolysis of lignin and the processes for lignin-derived bio-oil upgrading were reviewed. Various process parameters including pyrolysis temperature, reactor types, lignin characteristics, residence time, and feeding rate were discussed and the optimal parameter conditions for improved bio-oil yield and quality were concluded. In terms of lignin-derived bio-oil upgrading, three routes including pretreatment of lignin, catalytic upgrading, and co-pyrolysis of hydrogen-rich materials have been investigated. Zeolite cracking and hydrodeoxygenation (HDO) treatment are two main methods for catalytic upgrading of lignin-derived bio-oil. Factors affecting zeolite activity and the main zeolite catalytic mechanisms for lignin conversion were analyzed. Noble metal-based catalysts and metal sulfide catalysts are normally used as the HDO catalysts and the conversion mechanisms associated with a series of reacti...
Synergistic Effects between Lignin and Cellulose during Pyrolysis of Agricultural Waste
Energy & Fuels
Varying lignin and cellulose contents in agro-waste cause feed-stock to 12 respond differently during their thermochemical conversion. The effect of pyrolysis 13 temperature (400, 500, 600 o C) and feedstock composition on product yields and gas 14 composition of Olive-Kernel (OK) and Corn-Cobs (CC) was investigated in a lab-15 scale, fix bed reactor under a 20mL/min of nitrogen flow at atmospheric pressure. 16
Arabian Journal for Science and Engineering, 2020
The pyrolysis behavior of Turkish biomass samples such as hazelnut shell, almond shell, and sunflower stalk residue was studied using a thermogravimetric analysis (TGA) laboratory-scale setup. Biomass samples were characterized using the standard method of the Van Soest detergent analysis, and both the virgin biomass and fractions were investigated. The reaction temperature was increased to 900°C with a heating rate range between 2 and 60°C min −1 in the TGA experiments. Seven solid-state reaction models were applied to evaluate the obtained experimental TGA results. The heating rate was not the only parameter affecting the values of activation energy and the ratio of the main components such as the cellulose and lignin of the virgin biomass samples (almond shell, sunflower stalk, and hazelnut shell) also affected the value of the activated energy values. It was determined that a model fitting mechanism gives limited information to determine the exact activation energy values for the samples. The reaction order model provided straightforward and decisive results for all the biomass and lignin samples. Models of two-and three-dimensional diffusion were better suitable for the cellulose devolatilization. It was also determined that the activation energy of the lignin samples was similar regardless of the types of biomass. According to the kinetic calculations, the cellulose samples showed the highest activation energy values and the lignin samples had the lowest.
Renewable energy, 2007
Fundamental pyrolysis and combustion behaviors for several types of biomass are tested by a thermo-gravimetric analyzer. The main compositions of cellulose and lignin contents for several types of biomass are analyzed chemically. Based on the main composition results obtained, the experimental results for the actual biomass samples are compared with those for the simulated biomass, which is made of the mixture of the cellulose with lignin chemical. The morphological changes before and after the reactions are also observed by a scanning electron microscope. The main compositions in the biomass consisted of cellulose and lignin. The cellulose content was more than lignin for the biomass samples selected in this study. The reaction for the actual biomass samples proceeded with the two stages. The first and second stage corresponded to devolatilization and char combustion during combustion, respectively. The first stage showed rapid mass decrease caused by cellulose decomposition. At the second stage, lignin decomposed for pyrolysis and its char burned for combustion. For the biomass with higher cellulose content, the pyrolysis rate became faster. While, the biomass with higher lignin content gave slower pyrolysis rate. The cellulose and lignin content in the biomasses was one of the important parameters to evaluate the pyrolysis characteristics. The combustion characteristics for the actual biomass depends on the char morphology produced. r