Structure-Controlled Pyrolysis of Biomass with Sodium Hydroxide for Suppression of Tar Formation

Ohmukai, Yoshikage; Fujimoto, Kosuke; Hasegawa, Isao; Hayashi, Shigeya; Mae, Kazuhiro

doi:10.1252/jcej.07we262

Cited by 6 publications

(6 citation statements)

References 10 publications

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“…In contrast, when the samples were further carbonized to higher temperatures (400 °C), the chars obtained from the samples blended with NaOH and KOH via the wet-blending method have relatively higher yields, of 42.8 and 36.9 wt %, respectively, whereas the char yield of the samples without additives decreased extremely to 24.6 wt %. These results are in agreement with those reported by Ohmukai et al, , that char yield significantly increased with the suppression of tar evolution via the effect of alkali-metal hydroxides added in a cellulose structure. Moreover, the metal hydroxide additives may effectively cause cross-linking in the biomass structure, via dehydration, to obtain a higher char yield, even in the coexistence of PVC in the woody biomass samples.…”

Section: Resultssupporting

confidence: 94%

“…Consequently, we have further studied the effect of sodium hydroxide (NaOH) on the pyrolysis profile, to clarify the validity of the proposed method for tar suppression during pyrolysis. Through pyrolysis of a NaOH-loaded Douglas fir at 500 °C, a relatively high yield of char at 32 wt % and no tar products were obtained, because the dehydration reaction to form cross-linked structure was further proceeded by the effect of added alkali metal. , This suggests that the new biomass pyrolysis process with effective tar suppression and energy recovery can be proposed by adding metal hydroxide additives to the biomass structure. However, the waste from construction sites often includes waste woody board that has wallpaper (which is made from poly(vinyl chloride), PVC) affixed to it, or waste woody chips including crushed pipe made from PVC, and so on.…”

Section: Introductionmentioning

confidence: 99%

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A New Pyrolysis of Metal Hydroxide-Mixed Waste Biomass with Effective Chlorine Removal and Efficient Heat Recovery

Hayashi¹,

Amano²,

Niki³

et al. 2010

Ind. Eng. Chem. Res.

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Waste woody biomass samples including poly(vinyl chloride) (PVC), which were mixed with metal hydroxides as additives, were carbonized at 500 °C to investigate the catalytic effect of the additives on pyrolysis products and to elucidate the mechanism of biomass carbonization. The results showed that the yield of char significantly increased, whereas tar evolution was suppressed by the influence of metal hydroxides, even with the coexistence of PVC. Moreover, the interaction behaviors between the biomass structure including PVC and metal hydroxides were further investigated. It was clarified that the dehydration reaction to form a cross-linked structure in biomass by the effect of metal ion and the neutralization reaction between PVC and metal hydroxides were simultaneously occurred during the carbonization. The presence of chlorine component, which is one of corrosive substances, was confirmed in char structure by chlorine analysis. Therefore, a flushing method with warm and cold water was applied, to investigate the possibility of chlorine removal. The results showed that flushing with warm water and cold water are both effective for the removal of chlorine component in the char. Finally, the new pyrolysis process of NaOH-mixed waste biomass materials, including proposed heat recovery facilities, can be suggested as an effective system of biomass utilization for energy savings and CO 2 reduction.

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Section: Resultssupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

A New Pyrolysis of Metal Hydroxide-Mixed Waste Biomass with Effective Chlorine Removal and Efficient Heat Recovery

Hayashi¹,

Amano²,

Niki³

et al. 2010

Ind. Eng. Chem. Res.

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“…Structural analysis of pyrolyzed precursors, particularly in terms of cross-linking behavior, has been less investigated in literature for products estimation and mechanism clarification of cellulose, biomass, or even coal pyrolysis . Recently, our research group has focused on the examination of cross-linking behavior during pyrolysis and pretreatment of cellulose at low temperature by developing a new kinetic model and proposing new parameter indexes, so-called the degree of cross-linking. − On the basis of the discussions on previous kinetic models and the investigations of cross-linking behavior with structural analysis, the generalized pyrolysis pathway of cellulose, then, should be further modified to be applicable and describable for all pyrolysis conditions with different temperature and/or heating rates.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Cross-Linking Behavior during Pyrolysis of Cellulose for Elucidating Reaction Pathway

Chaiwat¹,

Hasegawa²,

Tani³

et al. 2009

Energy Fuels

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The analyses of structure change during pyrolysis of cellulose at different heating rates were investigated to clarify the existent behavior of the cross-linking reaction. For structural analyses of cellulose precursors, FTIR spectra and XRD patterns confirmed that the dehydration reaction to produce water and cross-liked precursor simultaneously occurred with the glycosidic reaction to produce tar during pyrolysis. On the basis of the assumptions that hydroxyl groups in cellulose converted to water, a new parameter index, so-called the degree of dehydration during pyrolysis, X p, including its distribution in char (X c) and tar (X t), was determined. For the cross-linking analyses at low heating rate, cross-linking reaction may occur until approximately 360 °C where X c reached its maximum, while the cross-linked tar seems to be released above 360 °C. For tar analyses, cross-linked dimer can be observed for slow pyrolysis, whereas tar products obtained by flash pyrolysis showed relatively higher yield in cellobiosan with no cross-linked volatiles. Finally, based on previous kinetic models, the modified pathway of cellulose pyrolysis was proposed by considering the proposed parameter related to the dehydration.

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“…Among them, weight loss peak of 20:1 Na loaded waste wood biomass was found at 280°C. Due to the increment in the char yields and decrement in the weight loss peak temperature, crystal structure of biomass major compound like cellulose was distorted through pyrolysis by Na + (NaOH) at even lower temperature, which was affected by subsequent thermal decomposition reaction [9]. Further, the elemental analysis of each char sample obtained by pyrolysis at 900°C was performed using the CHN corder ( Table 2).…”

Section: Pyrolysis Characteristics Of Mixing Thinning Waste Wood Biommentioning

confidence: 99%

“…Furthermore, the large amount of tar has to be reduced for controlling tar trouble as since many studies had not achieved reducing tar generation during pyrolysis because of the requirement of highest temperature for non-catalyst thermal decomposition of tar [7]. Many studies have been carried out by catalytic tar reduction techniques, such as alkali metals and metal oxides [8,9]. Among them, sodium hydroxide has a signifi cant effect on tar suppression and char yield increment.…”

Section: Introductionmentioning

confidence: 99%

Reactivity for pyrolysis and co2 gasification of alkali metal loaded waste wood char

Wang¹,

Apaer²,

Kurokawa³

et al. 2014

Int. J. SDP

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In this study, different carbonization processes were performed for thinning wood waste as organic industrial waste and forestry waste biomass to produce waste wood char, which is used as solid and gaseous fuel. Waste biomass samples were added to Na + (NaOH) using thermogravimetry with a differential thermal analyser (TG/DTA), where the behaviour of thermal decomposition and the effect of additive amount of alkali metal were investigated. Waste wood char yields were increased at the peak temperature and weight loss was decreased with the increment of Na + (NaOH) loaded value. The fi xed carbon amount of waste wood char was also increased with the maximum Na + (NaOH) loaded value at 100:1, and then it was decreased. Furthermore, in order to evaluate the effect of Na + (NaOH) loaded value on char reactivity, an isothermal CO 2 gasifi cation experiment was performed at temperatures between 700°C and 900°C for chars obtained by pyrolysis at 900°C. It was shown that the reaction rate was increased with increasing temperature and the reaction rate of raw char was markedly slower than Na + (NaOH) loaded char. The activation energies of char were in decreasing trend with increasing Na loaded value. However, the activation energies of CO 2 gasifi cation of char samples were conversely increased when Na + loaded on char sample was more than 50:1. If too large amounts of Na + (NaOH) were loaded on char sample, the rate of gasifi cation reaction and the activation energy will be decreased as Na + reacts with the char surface covering the gasifying agent.

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Structure-Controlled Pyrolysis of Biomass with Sodium Hydroxide for Suppression of Tar Formation

Cited by 6 publications

References 10 publications

A New Pyrolysis of Metal Hydroxide-Mixed Waste Biomass with Effective Chlorine Removal and Efficient Heat Recovery

A New Pyrolysis of Metal Hydroxide-Mixed Waste Biomass with Effective Chlorine Removal and Efficient Heat Recovery

Analysis of Cross-Linking Behavior during Pyrolysis of Cellulose for Elucidating Reaction Pathway

Reactivity for pyrolysis and co2 gasification of alkali metal loaded waste wood char

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