Composition Of Bio-oil Research Articles

Effect of pretreatment with Phanerochaete chrysosporium on physicochemical properties and pyrolysis behaviors of corn stover

Fungal pretreatment can selectively degrade partial biomass components, which undoubtedly exerts a significant influence on biomass pyrolysis behavior. The corn stover was pretreated with Phanerochaete chrysosporium, and its influence on the physicochemical properties and pyrolysis behaviors of biomass together with the product characteristics were investigated. The Phanerochaete chrysosporium was more active to degrade hemicellulose and lignin. The hemicellulose and lignin contents in corn stover were decreased by 35.14 % and 31.80 %, respectively, after five weeks pretreatment, compared to the untreated sample. The reaction activation energy decreased from 52.89 kJ·mol−1 for the untreated sample to 40.88 kJ·mol−1 for the sample pretreated for five weeks. The Phanerochaete chrysosporium pretreatment was beneficial to the biochar production but exerted an unfavorable effect on the texture structure. The Phanerochaete chrysosporium also had an obvious influence on the bio-oil compositions. This study can provide a scientific reference for the application of biological pretreatment for biomass pyrolysis technology.

Hydrothermal processing of waste pine wood into industrially useful products

An ongoing major outbreak of mountain pine beetle in Western Canada has provided a clear opportunity to utilize waste pinewood as a source of renewable energy. Therefore hydrothermal processing of waste pinewood as a feedstock for bio-oil and biochar production using subcritical and supercritical water technology was carried out in semi-batch mode to investigate the effect of pressure (200–400 bar) and temperature (300–400 °C) on the yield and composition of bio-oil. The pinewood samples have very high cellulose and hemicellulose content but low ash content and are thus a formidable feedstock for bioenergy production. The optimum conditions for the hydrothermal processing of the pinewood in a tubular reactor were found to be 400 °C and 250 bars with respect to biochar and bio-oil yield based on the highest calorific value analysis. Detailed characterization of bio-oil and biochar was performed using GCMS, NMR, SEM, calorific value, and elemental analysis, respectively. The critical components of bio-oil were found to be phenols, methoxyphenols, hydroxymethyl furfural (HMF), and vanillin, whereas as compared to the raw pine wood, the biochar was considerably lower H:C and O:C ratios than those of the unprocessed pinewood. The analyses of bio-oil by means of GCMS and 1H NMR showed that it was mainly composed of heterocyclic compounds, phenols, aldehydes and acids.

Fractionation by flash chromatography and molecular characterization of bio-oil by ultra-high-resolution mass spectrometry and NMR spectroscopy

Bio-oils obtained from the pyrolysis of lignocellulosic biomass are highly complex matrices with tens of thousands of organic compounds covering a wide polarity and mass range. Their upgrading into greener fuel or value-added chemicals requires an in-depth knowledge of their molecular composition prior and after valorization treatment, which can be obtained by different analytical techniques. Here, flash chromatography was employed as an efficient way to fractionate a bio-oil vacuum residue into four distinct fractions. This process was repeatable at both gravimetric and chromatographic levels and provided information about the weight contribution of each fraction to bio-oil composition. Achieved fractions were then characterized by ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance spectroscopy. These two techniques ensured the good repeatability of bio-oil fractionation at the molecular level and also highlighted molecular specificities of each fraction. Thus, flash chromatography provided quantitative information that was complementary to FT-ICR MS results. It also simplifies the bio-oil compositional analysis, making it possible to detect more compounds. Eventually, this fractionation process can also be used to target fraction or compounds of interest for bio-oil upgrading.

Study on co-pyrolysis and products of Chlorella vulgaris and rice straw catalyzed by activated carbon/HZSM-5 additives

The weight loss characteristics, product distribution and bio-oil composition of co-pyrolysis of rice straw (RS) and Chlorella vulgaris (CV) were investigated by microwave oven. Then, the catalytic effect of activated carbon (AC) and HZSM-5 on these characteristics were studied. Results showed that AC strongly improved co-pyrolysis weight loss characteristics and obtained maximum average weight loss rate (Ra) at 30% addition with 0.01639 wt.%/s. While HZSM-5 promoted the characteristics as addition was lower than 10%. In the case of compound additives, 20% A7H3 obtained the maximum Ra (0.01413 wt.%/s). Furthermore, both single AC and HZSM-5 showed negative effect on bio-oil production, while 20% A7H3 (AC/HZSM-5 = 7:3) achieved the maximum production (24%). For bio-oil composition, 30% A10H0 showed strong selectivity for phenol and N-heterocycle and 10% A0H10 showed strong aromatization capacity, and the addition of 20% A7H3 increased the hydrocarbons content from 20.79% to 31.63% compared with the blank group.

Microwave-assisted pyrolysis technology for bioenergy recovery: Mechanism, performance, and prospect

The emergence of bioenergy provides a solution to the environment and energy crises caused by the indiscriminate use of fossil fuels. Pyrolysis technology has broad application prospects in bioenergy production and waste disposal, providing a solid guarantee for the sustainable development of human beings and the environment. As an endothermic process, pyrolysis relies on external heat as an energy source. The introduction of microwave provides a different energy source for the pyrolysis process and exhibits a different pyrolysis performance due to its unique energy transfer mechanism. Conventional pyrolysis is conducive to the formation of bio-oil, whereas microwave-assisted pyrolysis can improve the composition of bio-oil and the surface properties of biochar. This article focuses on the advantages and limitations of microwave-assisted and conventional pyrolysis modes. Special attention is given to the differences in product distribution and properties and the economic feasibility of the two pyrolysis modes.

Catalytic pyrolysis of biomass with thermal treatment products of spent lithium-ion batteries for the upgrading of bio-oil and syngas

Thermal treatment is an efficient method to recycle spent lithium-ion batteries and the thermal treatment products are rich in valuable metals with catalytic activity such as Co and Ni. Therefore, the feasibility of using the thermal treatment products (PyNCM and PyLCO) of spent ternary lithium batteries (NCM) and lithium cobalt oxide batteries (LCO) as the cheap catalysts for biomass (wheat straw) pyrolysis was explored in this study. The catalytic effect of the typical components of PyNCM and PyLCO (Ni, Co, NiO and CoO) on the biomass pyrolysis process was also investigated for comparison purposes. The results showed that PyNCM and PyLCO could promote the devolatilization process of wheat straw. The Second order model could well describe the catalytic pyrolysis process of wheat straw based on the Coats-Redfern method, and the obtained activation energy was in the range of 79.00 kJ/mol to 83.90 kJ/mol. The PyNCM and PyLCO had good catalytic activity for enhancing the cracking of bio-oil to produce more gaseous products (syngas), especially for PyNCM, whose gas yield increased significantly from 15.70% to 22.26%. As for bio-oil compositions, the PyNCM and PyLCO both promoted the formation of hydrocarbon compounds and reduce the oxygen content of the obtained bio-oils. The increase of the hydrocarbon content was mainly attributed to the NiO and CoO components in PyNCM and PyLCO. In addition, both PyNCM and PyLCO increased the content and yield of H2 in the syngas. Especially for PyNCM, the content and yield of H2 increased 1.6 times and 5.5 times respectively compared with direct pyrolysis of wheat straw without catalyst. The mechanism of biomass catalytic pyrolysis in the presence of PyLCO and PyNCM was proposed and discussed. The catalytic effect of PyNCM on wheat straw pyrolysis was more distinct than that of PyLCO, which might be attributed to the positive synergistic effect of Ni and Co compounds in PyNCM. This study demonstrated that the thermal treatment products of spent lithium-ion batteries could be used as efficient catalysts for biomass pyrolysis products upgrading.

Combined effect of bio-oil composition and temperature on the stability of Ni spinel derived catalyst for hydrogen production by steam reforming

A challenge for scaling up hydrogen production by raw bio-oil steam reforming (SR) is the rapid catalyst deactivation that is strongly sensitive to the temperature and bio-oil composition. This work studies the combined effect of both variables on the stability of a Ni/Al2O3 catalyst with high Ni dispersion in the internal and external surfaces of the particles, obtained by reduction of a NiAl2O4. The raw bio-oil composition is modified by (i) removal of phenolic compounds by liquid–liquid extraction or (ii) use of an online pre-reforming step with dolomite. Then, SR tests of the bio-oils at 600 and 700 °C are carried out in a system with two online units, the first one for controlled deposition of pyrolytic lignin (and also pre-reforming with dolomite) and the second one (fluidized bed reactor) for the SR of the volatile oxygenates. The time on stream evolution of the conversion and products yields is related to the amount, nature and location of coke in the catalyst particles, determined with several techniques. For bio-oils with high or moderate phenolic content (raw or pre-reformed bio-oil, respectively), the SR at 600 °C leads to a moderate deactivation. However, at 700 °C, a refractory coke is formed, mainly composed of carbon filaments and turbostratic carbon among them that causes a rapid catalyst deactivation by blocking the external surface of the catalyst particle. Conversely, the removal of phenolic compounds from raw bio-oil leads to a more stable SR operation at 700 °C, because the formation of turbostratic carbon is slowed down.

The Consistency of Yields and Chemical Composition of HTL Bio-Oils from Lignins Produced by Different Preprocessing Technologies

This work evaluates the effect of feedstock type and composition on the conversion of lignin to liquid by solvolysis with formic acid as hydrogen donor (LtL), by analyzing the yields and molecular composition of the liquid products and interpreting them in terms of both the type and the preprocessing of the lignocellulosic biomass using chemometric data analysis. Lignin samples of different types and purities from softwood, hardwood, and grasses (rice straw and corn stover) have been converted to bio-oil, and the molecular composition analyzed and quantified using GC-MS. LtL solvolysis was found to be a robust method for lignin conversion in terms of converting all samples into bio-oils rich in phenolic compounds regardless of the purity of the lignin sample. The bio-oil yields ranged from 24–94 wt.% relative to lignin input and could be modelled well as a function of the elemental composition of the feedstock. On a molecular basis, the softwood-derived bio-oil contained the most guaiacol-derivatives, and syringol was correlated to hardwood. However, the connection between compounds in the bio-oil and lignin origin was less pronounced than the effects of the methods for biomass fractionation, showing that the pretreatment of the biomass dominates both the yield and molecular composition of the bio-oil and must be addressed as a primary concern when utilization of lignin in a biorefinery is planned.

Evaluation of crude bio-oil production from green tea waste (GTW) through pyrolysis over clamshell waste as a natural catalyst

The present study aimed to evaluate the effect of clamshell waste (CSW) as a natural catalyst to enhance the bio-oil yield and composition through pyrolysis with green tea waste (GTW). Initially, volatiles from GTW pyrolysis were allowed to pass through a capsule filled with CSW, which showed insignificant changes in bio-oil yield with 31.6%, 12.3%, 23.5%, and 11.6% increase in hydrocarbons, esters, alkanes/alkenes, and phenols, respectively. Further, CSW was directly mixed with GTW at ratios of 2.5%, 5.0%, 7.5%, and 10.0% (w/w) in comparison with the control (using GTW only). Results showed that caffeine was the dominant component in the bio-oil, representing 39.9% in the control, which could be used to enhance the process feasibility through biorefinery approach. Using 7.5% CSW enhanced the bio-oil yield by 10.2% over the control. In addition, CSW application showed desirable composition of the bio-oil. Nitrogen-containing compounds proportion of the bio-oil produced at 10% CSW represented 20.3% lower than that of the control. In addition, hydrocarbons, esters, and alkanes/alkenes proportions increased by 38.4%, 37.7%, and 71.6%, respectively, over the control. The present study introduces CSW as a natural catalyst for enhanced bio-oil yield and characteristics that could be used in many future applications.

Catalytic Upgrading of Residual Fat Pyrolysis Vapors over Activated Carbon Pellets into Hydrocarbons-like Fuels in a Two-Stage Reactor: Analysis of Hydrocarbons Composition and Physical-Chemistry Properties

This work investigated the influence of the reaction time and catalyst-to-residual fat ratio by catalytic upgrading from pyrolysis vapors of residual fat at 400 °C and 1.0 atmosphere, on the yields of reaction products, physicochemical properties (density, kinematic viscosity, and acid value) and chemical composition of bio-oils, over a catalyst fixed-bed reactor of activated carbon pellets impregnated with 10.0 M NaOH, in semi-pilot scale. The experiments were carried out at 400 °C and 1.0 atmosphere, using a process schema consisting of a thermal cracking reactor of 2.0 L coupled to a catalyst fixed-bed reactor of 53 mL, without catalyst and using 5.0%, 7.5%, and 10.0% (wt.) activated carbon pellets impregnated with 10.0 M NaOH, in batch mode. Results show yields of bio-oil decreasing with increasing catalyst-to-tallow ratio. The GC-MS of liquid reaction products identified the presence of hydrocarbons (alkanes, alkenes, ring-containing alkanes, ring-containing alkenes, and aromatics) and oxygenates (carboxylic acids, ketones, esters, alcohols, and aldehydes). For all the pyrolysis and catalytic cracking experiments, the hydrocarbon selectivity in bio-oil increases with increasing reaction time, while those of oxygenates decrease, reaching concentrations of hydrocarbons up to 95.35% (area).

Influence of interaction between biomass inorganic components and volatiles on corncob pyrolysis and char structure

A thorough understanding of the mechanism of interaction between biomass inorganic components (BICs) and volatiles is critical for the pretreatment and subsequent utilization of pyrolysis products. As a result, the low- and medium-temperature pyrolysis features of corncob before and after deashing with hydrochloric acid were investigated via the analysis of product distribution, bio-oil, and bio-gas composition, organic functional groups, and char's two-dimensional correlation infrared spectrum. BICs accelerated secondary pyrolysis of corncob and improved molecular structure rearrangement of char. CO2 production was reduced by 29% on average due to deashing, while levoglucosan (LG) yield was raised with a maximum relative content of 29.1%. At low temperatures (< 350°C), BICs enhanced depolymerization of biomass polymer and promoted glycosidic bond breaking, dehydration, and ring-opening reactions, resulting in a reduction in CO and COC structures in char. At medium temperatures (350– 600°C), BICs promoted the dehydroxymethylation and cyclization of linear structures to generate cyclopentanone and benzenes, increasing the generation of CC, CH, and aromatic structures in the char. The results contribute to a better understanding of the interaction mechanism between BICs and pyrolysis volatiles.

Development of process-product relations for the pyrolysis of sisal residue

This research aimed to examine the upgrading of the sisal residue bio-oil from the relations between process conditions of the fast pyrolysis and the properties of the fluid. The bio-oil was produced in a pilot unit with a fluidized bed reactor by varying the nitrogen flow rate, biomass mass flow, temperature, and pressure. Overall, the bio-oil composition was intensely dependent on the process parameters. The pressure at the lowest value was the best condition for obtaining the bio-oil in high yield (up to 17 wt%), with the highest monomer yield (44.51 wt%) and the lowest O/C ratio (0.11). The characterization techniques applied revealed remarkably distinct characteristics between the bio-oil of sisal residue and other biomass. The sisal residue bio-oil had a lower oxygen and water content, higher thermal stability, higher degree of depolymerization, and a higher yield of aliphatics, naphthalenes, and alkylphenols.

Efficient pyrolysis process of lignin over dual catalyst bed for the production of Phenols and Aromatics

In this study, we developed an effective method for converting lignin into useful compounds to replace fossil-based products. The dual catalyst bed was used to catalyze the resulting pyrolysis vapors over it. A maximum bio-oil yield of 44.058 wt.% and gas yield of 28.9 wt.% along with 26.52 wt.% of bio-char is achieved. The biomass product (gas and Bio-oil) was characterized using GC-FID and GC–MS. The dual catalyst bed showed a considerable effect on the bio-oil composition and oxygenates were reduced. The bio-oil exhibit a high quantity of phenols and aromatic. In the gas product, the hydrogen yield has been enhanced from 14.6% to 21.4% and methane yield was enhanced from 20.8% to 23.1%.

Catalytic co-conversion of poplar pyrolysis vapor and methanol for aromatics production via ex-situ configuration

The ex-situ catalytic co-conversion of poplar pyrolysis vapor and methanol over HZSM-5 was conducted in a bench-scale continuous feeding setup. Methanol was introduced into reaction system through mid-section addition. The effects of catalytic temperature, methanol/poplar mass ratio, time-on-stream on the products distribution and bio-oil composition were investigated. In addition, the evident synergistic effects for promotion of aromatics and reduction of coke were revealed in the co-conversion process. Under the mid-section methanol addition system, aromatics especially monoaromatics in bio-oil increased significantly while the phenolics and other oxygenates reduced considerably to a rather low level. When the catalytic temperature and methanol/poplar mass ratio were 500 ℃ and 1.5:1, the maximum aromatics yield of 9.54 wt% was obtained with organics yield enhanced to 22.49 wt%. Meanwhile, the positive synergistic effect for aromatics and the negative synergistic effect for coke achieved 90.12% and 29.82% respectively. The mid-section methanol addition also successfully prolonged the lifetime of catalyst by 50% compared to poplar single-conversion. The characterization of catalysts indicated that the BET specific surface area for co-conversion exhibited a minor change with 1.3% reduction after regeneration. The acidity of regenerated catalyst in co-conversion was also stronger than that in poplar single-conversion. The reusability of catalyst didn’t decrease to a certain extent until the fourth reaction-regeneration recycle run. This paper proposed a new efficient co-utilization strategy for biomass and methanol, which stimulated the strong synergistic effect between the two feedstocks.

Co-pyrolysis of de-oiled microalgal biomass residue and waste tires: Deeper insights from thermal kinetics, behaviors, drivers, bio-oils, bio-chars, and in-situ evolved gases analyses

The effective utilization of biomass and waste streams has drawn significant attention in light of the energy crisis and requirement for carbon footprint reduction. This study aimed to characterize the pyrolytic behaviors, drivers, kinetics, in-situ evolved gases characteristics, bio-oils, bio-chars, and product distributions of the de-oiled Nannochloropsis sp. residue (NSR) and waste tires (WT) via TG-FTIR-MS and Fixed bed reactor. The D(TG) analysis of the co-pyrolysis was characterized by two decomposition stages: the first stage was the degradation of NSR (150–350 °C), and the second stage (350–550 °C) was ascribed to the degradation of NSR-WT blends. The discrepancy in experimental and theoretical weight loss (ΔW) was less than zero for the blends containing 80, 60, and 50% NSR when the temperature exceeded 210 °C, which confirmed the existence of a strong synergistic effect. The average activation energy (Eavg) was 167.37 kJ/mol and 221.79 kJ/mol for the NSR and WT devolatilization, respectively. To gain more insight into the pyrolytic performance, solid, liquid, and gas products were analyzed by different analytical techniques. The results revealed that the co-pyrolysis significantly modified the chemical composition of bio-oil, leading to an increase in bio-oil yield up to 48.96 wt%. Meanwhile, it seemed conceivable to modify the structure and improve the quality of bio-oils and biochar by co-pyrolysis. This work provides a practical and theoretical understanding of optimizing energy generation, emission control, and products recovery during the co-pyrolysis process.

Study on the effect of red mud and its component oxides on the composition of bio-oil derived from corn stover catalytic pyrolysis

Red mud (RM) waste rich in metal elements was selected as a cheap catalyst for fast catalytic pyrolysis to obtain high value-added bio-oil. The structural patterns and the main oxide components of the RM were determined. In addition, the catalytic effects and mechanisms of the metal oxide components on the bio-oil composition from corn stover (CS) was elucidated. The results showed the content of ketones, furans and alkylphenol significantly increased, while the content of acids and aldehydes greatly decreased under the catalytic effects of the 800 ℃-calcined RM. Fe2O3 and CaO were the main contributor. CaO promoted the production of ketones, and the catalytic effect of Fe2O3 resulted in a good selectivity for acids and furans. Al2O3, TiO2 and SiO2 inhibited the production of methoxyphenols and promoted the production of acids. Main oxide components promoted the production of alkylphenols. The results provided scientific guidance for producing high value-added bio-oil with cheap RM catalyst.

Pyrolysis of the food waste collected from catering and households under different temperatures: Assessing the evolution of char structure and bio-oil composition

The accumulation of food waste brings several challenges to the economy and environment, its pyrolysis technology has received extensive attention. The present investigation mainly focused on the evolution of char structure and bio-oil composition during the pyrolysis process of the typical food waste, which was characterized by FT-IR, Raman, UV, and GC/MS. The experimental results show that the bio-oil has the highest yield at 400–600 ℃ and remains basically unchanged (around 40%), and decreases apparently at 700 ℃ due to the secondary thermal cracking and reforming. With the increase of temperature, the cracking of macromolecular organic matter in the food waste becomes more intense, resulting in the yield of bio-char gradually decreasing from 34.90% to 23.54% in the range of 400–700 ℃. The ratio of small aromatic ring systems to large aromatic systems (I(VR+VL+GR)/ID) in the bio-chars increases apparently with temperature, and the amounts of aromatic rings in bio-oil also increase gradually. The content and relative percentage of N-compounds are the largest in bio-oil, and the content of it reaches the maximum value at 500 ℃, while the changes in its relative percentage are slightly different, which decreases from 33.57% to 24.15% at 400–600 ℃, and then increases apparent to 40.63% at 700 ℃. Hydrocarbons are also one of the main components in bio-oil, their relative percentage decreases from 17.70% to 2.40% in the range of 400–700 ℃. In addition, Carboxylic acid, alcohols, esters, ketones, saccharides, phenols, and other substances are also contained in bio-oil, and its content has different changing trends with temperature.

Catalytic hydrothermal liquefaction of sewage sludge over alumina-based and attapulgite-based heterogeneous catalysts

In this study, Co/γ-Al2O3, Co-Mo/γ-Al2O3, Co/attapulgite (ATP) and Co-Mo/ATP catalysts were prepared and applied for hydrothermal liquefaction (HTL) of sewage sludge (SS) to produce bio-oil. The properties of the catalysts were characterized by various techniques (N2 physisorption, ICP, XRD and XPS). The mesoporous nature of synthesized catalysts was conformed. Beside, Co2+ and Mo6+ particles were responsible as the major active species for catalytic HTL reactions. The effect of carrier and metal type, loading of catalyst on product yields and composition of bio-oil was studied. The highest bio-oil yield of 31.36 wt% was achieved in the presence of 10 wt% catalyst loading. The main components of bio-oil were phenols, N-containing compounds and hydrocarbons, and the increased selectivity to hydrocarbons with Co-Mo/ATP was observed. Meanwhile, TGA results showed that Co-Mo/ATP increased the low boiling point fraction (<410 °C) of bio-oil to 81.19 wt%. Additionally, catalytic HTL of SS resulted in higher carbon recovery, increasing from 55.61 to 92.24 wt%. Finally, the potential reaction mechanism of the catalysts on HTL of SS was proposed. Overall, this study provides valuable information for bio-oil production from sewage plant and further HTL implementation with ATP based catalyst, improving energy efficiency and alleviating the energy shortage.

A comprehensive review of bio-oil, bio-binder and bio-asphalt materials: Their source, composition, preparation and performance

To promote the application of bio-materials and provide a direction for their further researches, this paper comprehensively summarizes the research progress of biomaterials in recent years. The review results show that bio-oil is a mixture obtained from different biomasses through pyrolysis, alcoholysis, acidolysis, high liquefaction, etc., and those biomasses mainly include wood fiber type, waste oil type and animal manure type. Bio-binder refers to the product of bio-oil processed by distillation, extraction oxidation and polymer modification, and it can be served as a modifier, diluent or substitute material of asphalt; the main chemical components of bio-oil include ethers, esters, aldehydes, ketones, phenols, organic acids, alcohols and sugars. Bio-asphalt is obtained by adding bio-binder into the petroleum asphalt for modification or blending, and the shear temperature and shear rate of bio-asphalt derived from wood fiber type and waste oil type are usually higher than that of bio-asphalt derived from swine manure. Compared with petroleum asphalt, bio-asphalt binder usually shows lower high-temperature performance as well as higher low-temperature performance and aging resistance. Also, bio-asphalt mixture generally exhibits lower high-temperature stability, higher low-temperature crack resistance and water stability than petroleum asphalt mixture. Future studies should be conducted combining with the source, composition, preparation, properties and oil production rate of bio-oil. First, how to raise the bio-binder content in bio-asphalt as much as possible while ensuring the sufficient performance becomes the focus of future researches. Second, the micro reaction mechanism between bio-binder and petroleum asphalt should be illustrated in depth. Moreover, developing a complete and unifying technical standard and application specification of bio-asphalt technology is necessary for future researches. Furthermore, determining the optimum bio-binder potentially used as the substitute of petroleum asphalt is also an interesting topic.

On the primary devolatilization of hemicellulose

This paper presents validation cases on a reaction mechanism for the primary devolatilization of hemicellulose called “hemi-FC.” The analysis incorporates depolymerization via random scission; charring via monomer decomposition, semichar decomposition, and thermal annealing; fragmentation statistics; and the flash distillation analogy. It predicts the yields and elemental compositions of bio-oil and char, oil molecular weight distributions, and the yields of CO, CO2, H2O, H2, and light oxygenates. A single set of model parameters accurately interprets the partitioning of hemicellulose with cation levels from 5000 to 30,000 ppmw into oil, noncondensables, and solid residue for temperatures to 900 °C, heating rates from 10 °C/min to 6000 °C/s, contact times after heatup to 1800 s, and pressures of vacuum and 0.1 MPa. The model results are generally within useful quantitative tolerances of the measured values across the domain of test conditions. Nonetheless, the commercial xylans that have been tested devolatilize at much cooler temperatures than cellulose and produce more gas and char and less bio-oil primarily because their decomposition is strongly catalyzed by excessive residual amounts of Na and Ca from the hemicellulose extraction process. These cation loadings are definitely heavy enough to grossly distort the dynamics of the spontaneous reaction channels and ultimate devolatilization behavior. Consequently, the spontaneous, uncatalyzed reaction channels for hemicellulose devolatilization remain uncharacterized even while they are bound to be prominent in the devolatilization of many natural hemicellulose forms.