Cellulose Thermal Decomposition Kinetics: Global Mass Loss Kinetics

Milosavljevic, Ivan; Suuberg, Eric M.

doi:10.1021/ie00043a009

Cited by 246 publications

(178 citation statements)

References 36 publications

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“…This configurational difference results in a higher Ea for the thermal decomposition of mercerized linters. Considering the Ea values obtained from the thermogravimetric analyses described in literature, it can be inferred that the data discussed herein are inside the range mentioned for celluloses obtained from different sources, that is, from 179.5 to 190.6 kJ mol -1 [47] and from 140 to 155 kJ mol -1 [48] .…”

Section: Characterization Of Cellulose Acetatessupporting

confidence: 52%

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Morgado

Frollini

2011

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Abstract:Cellulose acetates with different degrees of substitution (DS, from 0.6 to 1.9) were prepared from previously mercerized linter cellulose, in a homogeneous medium, using N,N-dimethylacetamide/lithium chloride as a solvent system. The influence of different degrees of substitution on the properties of cellulose acetates was investigated using thermogravimetric analyses (TGA). Quantitative methods were applied to the thermogravimetric curves in order to determine the apparent activation energy (Ea) related to the thermal decomposition of untreated and mercerized celluloses and cellulose acetates. Ea values were calculated using Broido's method and considering dynamic conditions. Ea values of 158 and 187 kJ mol -1 were obtained for untreated and mercerized cellulose, respectively. A previous study showed that C6OH is the most reactive site for acetylation, probably due to the steric hindrance of C2 and C3. The C6OH takes part in the first step of cellulose decomposition, leading to the formation of levoglucosan and, when it is changed to C6OCOCH 3 , the results indicate that the mechanism of thermal decomposition changes to one with a lower Ea. A linear correlation between Ea and the DS of the acetates prepared in the present work was identified. Keywords: Linter cellulose, cellulose acetates, thermal decomposition. Decomposição Térmica de Celulose de Linter Mercerizado e seus Acetatos Obtidos a partir de Reação HomogêneaResumo: Acetatos de celulose com graus de substituição, GS, variando entre 0,6 e 1,9, foram preparados previamente a partir de celulose de linter mercerizado, em meio homogêneo, usando N,N-dimetilacetamida/cloreto de lítio como sistema de solvente. A influência de diferentes graus de substituição nas propriedades dos acetatos de celulose foi investigada usando a análise termogravimétrica (TGA). Métodos quantitativos foram aplicados nas curvas termogravimétricas obtidas a fim de determinar a energia de ativação aparente (Ea) relacionado à decomposição térmica de celulose não-tratada e mercerizada e acetatos de celulose. Valores de Ea foram calculados usando o método de Broido e considerando condições dinâmicas. Valores de Ea de 158 e 187 kJ mol -1 foram obtidos para a celulose não-tratada e mercerizada, respectivamente. Em trabalho anterior verificou-se que o C6OH é o sítio mais reativo na acetilação, provavelmente devido ao impedimento estérico de C2 e C3. O C6OH participa da primeira etapa de decomposição da celulose, levando à formação de levoglucosana e, quando se tem a substituição para C6OCOCH 3 , o resultado indica que o mecanismo de decomposição térmica muda para um com Ea menor. Uma correlação linear entre Ea e o GS dos acetatos preparados no presente trabalho foi identificada. Palavras-chave: Celulose de linter, acetatos de celulose, decomposição térmica.

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Section: Characterization Of Cellulose Acetatessupporting

confidence: 52%

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Morgado

Frollini

2011

Polímeros

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“…It has been suggested that cellulose decomposes in the range 300-400 8C with apparent activation energy around 150-250 kJ/mol [13,[16][17][18].…”

Section: Pyrolysis: Kinetic Parametersmentioning

confidence: 99%

Kinetics of pyrolysis and combustion of pine needles and cones

Font

Conesa

Moltó

et al. 2009

Journal of Analytical and Applied Pyrolysis

106

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“…For the experiment presented in Figure 3.2, we measured an activation energy of 110 kJ/mol and an Arrhenius preexponential of 5.7 × 10 11 based on the early log linear stages of the ARC-observed reaction. Milosavljevic and Suuberg (1995) summarize activation energies for cellulose thermal decomposition reported in the literature ranging from 109 to 250 kJ/mol. Antal et al (1980) noted three types of activation energies in the literature, depending on how the temperature recording devices were coupled to the sample.…”

Section: Thermal Behavior Of Cellulosementioning

confidence: 99%

Evaluation of Exothermic Reactions from Bulk-Vitrification Melter Feeds Containing Cellulose

Scheele¹,

McNamara²,

Bagaasen³

et al. 2007

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SummaryThe baseline bulk-vitrification (BV) process (also known as in-container vitrification ICV™) includes a mixer/dryer to convert liquid waste into a dried, blended feed for vitrification. Feed preparation includes blending liquid low-activity waste (LAW) with glass-forming minerals and cellulose and drying the mixture to a suitable dryness, consistency, and particle size for transport to the ICV TM container.This drying process is conducted under vacuum in the temperature range of 60 to 80°C. The nominal melting process starts with a refractory-lined metal box that is partially filled with feed. The refractory lining is referred to as the castable refractory block (CRB). Heat is applied in the form of electrical power through two graphite electrodes. Initially, the electrical current is carried through a graphite starter path, but as the feed is heated, it forms a molten glass that becomes the electrical conductor. The feed subsides as the glass is formed, allowing more feed to be added to the top of the melt in a feed-while-melt operation that continues until the box is filled to the desired level with glass.A full-scale (FS) test (FS-38C) was conducted in CY06 (Witwer et al. 2007), which evaluated using a thick cold cap of feed to condense volatile contaminants and increase the single-pass retention of those contaminants in the BV melt. Using a thick cold cap resulted in high single-pass retentions and significant quantities of molten ionic salt (MIS) outside the CRB panels, which is thought to be related to the thick cold cap.The main problem with MIS outside of the CRB panels is that radionuclides in the LAW are also initially salts and are concentrated in the MIS. If the MIS migrates to cooler regions of the ICV™, the salts either do not decompose, or they partially decompose to form glasses with poor durability. This is undesirable as the unreacted salts and low-durability glasses are susceptible to leaching after disposal. The significant quantities of MIS in the FS-38C test are also thought to be related to the high concentration of lowmelting nitrates in the Tank 241-S-109 simulant (S-109) used for the test.Because Tc is carried into the CRB by MIS, decreasing MIS migration into the CRB would proportionally decrease the concentration of the soluble Tc in the refractory lining. Current activities are exploring several methods for controlling MIS migration but focus mainly on methods to decrease the MIS mobility within the BV feed. These studies find that the MIS mobility is decreased by 1) increasing the specific surface area of solids and 2) adding organic carbon to denitrate the feed and reduce the amount of MIS. Using solids with fine grains or grinding the existing solids (soil) reduces migration by bonding free MIS to solid grains by capillary forces. Adding organic carbon decreases the amount of MIS in the feed by destroying its main components, nitrates and nitrites, at temperatures below 300°C. iv However, because of potential increased reactivity at off-normal conditions, the project pursue...

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Cellulose Thermal Decomposition Kinetics: Global Mass Loss Kinetics

Cited by 246 publications

References 36 publications

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Kinetics of pyrolysis and combustion of pine needles and cones

Evaluation of Exothermic Reactions from Bulk-Vitrification Melter Feeds Containing Cellulose

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