Kinetics Analysis of Wheat Straw Pulping Process

2013 ◽  
Vol 860-863 ◽  
pp. 1012-1016 ◽  
Author(s):  
Ming Xian Cui ◽  
Wei Song ◽  
Zong Yu Liu
Keyword(s):  
Activation Energy ◽  
Wheat Straw ◽  
Lignin Content ◽  
Removal Rate ◽  
Black Liquor ◽  
Alkali Concentration ◽  
Slow Stage ◽  
First Order ◽  
Lignin Removal ◽  
Two Stages

This paper analyzes the delignification mechanism of wheat straw pulping process. The lignin removal of pulping process is left in black liquor. The higher the black liquor lignin content is, the bigger the lignin of paper pulp is removed. The relations of black liquor lignin content and alkali concentration to pulping time are described in detail. The results show that delignification process is divided into two stages: quick and slow stage. The lignin removal rate in the first stage is much higher than the second, that is, lignin has been removed more sufficiently after quick stage. In first stage, reaction order of delignification is 1.0, and 0.7 with respect to OH-, the activation energy is 38.62 kJ • mol-1. The latter delignification also belongs to the first-order reaction and 4.4 with respect to OH-, the activation energy is 75.56 kJ • mol-1. Apparently, slow stage needs to consume large amounts of energy to removal lignin.

Kinetics Research of Wheat Straw Atmospheric Pressure Pulping with Microwave Radiation

2012 ◽  
Vol 610-613 ◽  
pp. 1726-1730
Author(s):  
Hong Zhu ◽  
Hong Xu Qiao
Keyword(s):  
Activation Energy ◽  
Wheat Straw ◽  
Microwave Radiation ◽  
Atmospheric Pressure ◽  
Lignin Content ◽  
Removal Rate ◽  
Black Liquor ◽  
Alkali Concentration ◽  
Paper Pulp ◽  
Lignin Removal

The lignin removal of pulping process is left in black liquor, and with relation to the paper pulp lignin. The higher the black liquor lignin content is, the bigger the lignin of paper pulp is removed. This paper analyzes the delignification mechanism of wheat straw atmospheric pressure pulping with microwave radiation. The relations of black liquor lignin content and alkali concentration to pulping time are described in detail. The results show that delignification process is divided into two stages: quick stage and residual stage. The lignin removal rate in the first stage is much higher than the second stage, that is, lignin has been removed more sufficiently after quick stage. In first stage, reaction order of delignification is 1.0, and 0.7 with respect to OH-, the activation energy is 38.62 kJ • mol-1. The latter delignification also belongs to the first-order reaction and 4.4 with respect to OH-, the activation energy is 75.56 kJ • mol-1. Apparently, residual stage needs to consume large amounts of energy to removal lignin.

Combustion properties of reduced-lignin black liquors

TAPPI Journal ◽  
2014 ◽  
Vol 13 (8) ◽  
pp. 81-90 ◽  
Author(s):  
NIKLAS VÄHÄ-SAVO ◽  
NIKOLAI DEMARTINI ◽  
RUFUS ZIESIG ◽  
PER TOMANI ◽  
HANS THELIANDER ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Lignin Content ◽  
Black Liquor ◽  
Nitrogen Atmosphere ◽  
Pulp Mills ◽  
Lignin Removal ◽  
Nitric Oxide Formation ◽  
Combustion Properties ◽  
Black Liquors ◽  
Almost All

The growing interest in production of green chemicals and biofuels from biomass provides an incentive for pulp mills to identify new possibilities in recovering more wood components from the pulping process. One possibility is to use lignin, separated from black liquor. We undertook this work to determine the combustion properties of reduced-lignin black liquors—two kraft liquors and one soda liquor—in a laboratory-scale, singleparticle furnace. The combustion times, maximum swollen volume, nitric oxide formation, cyanate formation, and sulfur release were measured for the original liquors, the filtrates, and intermediate levels of lignin reduction. Combustion experiments were conducted at 900°C in 10% oxygen. Cyanate formation experiments were carried out by pyrolyzing the droplets at 800°C in 100% nitrogen to form a char. The chars were then gasified at 800°C in a 13% carbon dioxide/87% nitrogen atmosphere to obtain the smelt. Sulfur release was studied by pyrolyzing the samples at temperatures ranging from 300°C to 900°C. Liquors with the lowest lignin content had a smaller maximum swollen volume than the original sample. The devolatilization time was not affected by the lignin removal to any great extent, but lignin removal did have a clear effect on the char burning time. The amount of formed nitric oxide (g N/kg black liquor solids) remained constant or decreased slightly with increasing lignin removal in the kraft liquor samples, while for the soda samples the amount of nitric oxide formed increased. The amount of cyanate decreased clearly when comparing the samples with lowest lignin content to the original liquor samples. The peak sulfur release occurred at 500°C for both kraft liquors. In almost all experiments, the share of sulfur released was highest for the original samples and lowest for the sample with lowest lignin content. These results provide new data on combustion properties for reduced-lignin black liquors and indicate that for lignin removal levels up to about 20%, no significant changes are expected in the combustion behavior.

The Pyrolysis Behavior of Alkali Lignin Oxygenized by Hydrogen Peroxide in Ionic Liquid 1-Butyl-3-Methylimidazolium Chloride ([BMIm]Cl)

2014 ◽  
Vol 598 ◽  
pp. 86-89
Author(s):  
Zhong Lian Yang ◽  
Ming Qiang Chen ◽  
Zhong Yi Luan ◽  
Wen Tao Zhang
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Ionic Liquid ◽  
Black Liquor ◽  
Mixed Solution ◽  
Alkali Lignin ◽  
Pyrolysis Reaction ◽  
First Order ◽  
Pyrolysis Behavior

In order to make better use of lignin, a mixed solution with isopyknic hydrogen peroxide 30% aqueous solution and an ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIm]Cl) was used to oxygenize alkali lignin from black liquor. The pyrolysis behavior of the treated alkali lignin (Regenerated ALG) was investigated via TGA. The kinetic controlling temperature range of the Regenerated ALG pyrolysis is between 533K and 649K approved by TG/DTG/DTA data, and the dominated pyrolysis is occurred below 574.7K, which was calculated from a kinetics model using Coats-Redfern method with a first order pyrolysis reaction. The activation energy of the Regenerated ALG also reached up to 105.675kJ/mol, which is 2.2 times greater than the non-treated one.

Evolution of hardness and transmittance in irradiated LiF single crystals at elevated temperatures

1992 ◽  
Vol 7 (10) ◽  
pp. 2833-2839 ◽  
Author(s):  
Hung-Ye Lin ◽  
Yu-Zen Tsai ◽  
Sanboh Lee
Keyword(s):  
Activation Energy ◽  
Optical Absorption ◽  
Single Crystals ◽  
Vickers Hardness ◽  
Elevated Temperatures ◽  
Kinetic Process ◽  
Order Kinetic ◽  
First Order ◽  
Γ Rays ◽  
Two Stages

The evolution of hardness and transmittance of irradiated LiF single crystals at elevated temperatures has been investigated. The Vickers hardness is proportional to φ1/3 where φ is the dosage of γ-rays. The thermal annealing of hardness which is analyzed according to a first-order kinetic process has one stage for φ = 100 KGy and two stages for φ ≥ 250 KGy. For a given dosage, the activation energy of stage I is larger than that of stage II. The transmittance of irradiated LiF crystals is attributed to F, M, R1, and R2 centers. The transmittance decreases with increasing time at the brief durations, then oscillates, and finally increases monotonically. The region in which the transmittance increases monotonically with time is simulated by a second-order kinetic process of the color center. The activation energy of optical absorption was determined. Comparing both activation energies of hardness and optical absorption, we find that the mechanism of the kinetic process for hardness differs from that for optical absorption.

Temperature and effective alkali effect on brown pulp kraft cooking

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaqueline Silveira Comelato Favaro ◽  
Gustavo Ventorim ◽  
Iliane Rodrigues de Oliveira ◽  
Cláudia Rodrigues de Oliveira
Keyword(s):  
Lignin Content ◽  
Removal Rate ◽  
Linear Trend ◽  
Total Yield ◽  
Eucalyptus Grandis ◽  
Kappa Number ◽  
Factor H ◽  
Pulp Yield ◽  
Lignin Removal ◽  
Kraft Cooking

Abstract One way to obtain high quality pulp production is to improve selectivity delignification of step, maximize yield. Brown pulp yield and chemical composition were studied, with variation of temperature and effective alkali in Kraft cooking. Considering that these variables directly affect lignin removal rate and final product quality. Industrial wood chips from Eucalyptus grandis x Eucalyptus urophylla hybrids were used in this study. The cooking was performed to obtain pulps with kappa number 13, 15 and 17 for temperatures 155 °C, 160 °C and 165 °C, using the same Factor H (695). Yields were analyzed according to: total yield, rejects content and screened pulp yield. Klason lignin content, wood and pulp sugars, levels of hexenuronic acids in pulp were also determined. Results indicate that lower cooking temperatures are beneficial in relation to cooking performance, selectivity and preservation of xylans. With a screened pulp yield of 57.1 % for KN 17 at the lowest temperature 155 ºC and 55.3 % at the same KN at 165 ºC. The lowest screened pulp yield obtained, 51 %, was for KN 13 at 165 ºC, with 54.1 % with the same KN at 155 ºC. Evidencing a decreasing linear trend of screened pulp yield with temperature increase and kappa number reduction.

Changes in wheat straw cell walls during ozone pretreatment

Holzforschung ◽  
2020 ◽  
Vol 74 (12) ◽  
pp. 1157-1167
Author(s):  
Elena M. Ben’ko ◽  
Dmitriy G. Chukhchin ◽  
Valeriy V. Lunin
Keyword(s):  
Cell Wall ◽  
Wheat Straw ◽  
Plant Biomass ◽  
Lignin Content ◽  
Cellulose Microfibrils ◽  
Primary Cell Wall ◽  
Residual Lignin ◽  
Intercellular Substance ◽  
Lignin Removal ◽  
Wall Stiffness

AbstractTreatment of plant biomass with ozone is a promising delignification method. It was shown that lignin removal from the cell wall during ozonation was limited by topochemical reactions and toke place in the secondary rather in the primary cell wall. The separation of cellulose microfibrils, the loss of cell wall stiffness and complete removal of intercellular substance during the delignification process were visualized by SEM. The dependence of the average diameter of the cellulose microfibril aggregates in the cell wall of ozonized straw on ozone consumption was studied. Lignin removal caused an increase of size of cellulose microfibrils aggregates. It was demonstrated that there was an optimal degree of delignification, at which cellulose became more accessible to enzymes in the subsequent bioconversion processes. The data on the ozone consumption, residual lignin content, and sugars yield in the enzymatic hydrolysis of ozonized wheat straw were obtained. It was also found that the optimum delignification degree for sugars yield was ≈10% of residual lignin content and optimum ozone consumption was 2 mol·О3/mol C9PPU (phenylpropane structural unit) of lignin in raw straw.

scholarly journals Clean production of corn stover pulp using KOH+NH4OH solution and its kinetic during delignification

2012 ◽  
Vol 18 (2) ◽  
pp. 137-145 ◽  
Author(s):  
Yong Sun ◽  
Gang Yang ◽  
Jin-Ping Zhang ◽  
Ming-Shun Yao
Keyword(s):  
Activation Energy ◽  
Corn Stover ◽  
Reaction Temperature ◽  
The Self ◽  
Organic Matters ◽  
First Order ◽  
Lignin Removal ◽  
Ft Ir ◽  
Three Stages ◽  
Kinetics Of

The self-made KOH together with NH4OH pulping of corn stover was investigated. The combined alkaline system could effectively remove lignin during pulping. There are three stages of lignin removal during delginification. Approximately 90% of lignin could be removed after temperature reached 150?C for over 30 minutes. The p-hydroxyl phenol groups in lignin could be completely removed during the delignification reaction. The tendency of the increase of the crystalline degree of cellulose is observed with increase of reaction temperature. The kinetics of delignification is found to be the first order with respect to the remained lignin and the 0.4 order with respect to the remained hydroxide concentration. The activation energy of delignification is 23 kJ/mol. The solution obtained from precipitation of lignin is rich in nitrogen, phosphorous, potassium elements and organic matters. Various techniques including FT-IR, GPC, DSC, were applied to characterize the acid precipitated lignin. The result shows that the lignin with the polydispersity of 1.4 still maintains the p-coumaryl, coniferyl, and sinapyl units in its matrix.

Thermogravimetric Study on the Co-Pyrolysis Characteristics of Bituminous Coal and Wheat Straw

2014 ◽  
Vol 1070-1072 ◽  
pp. 146-151
Author(s):  
Xin Ping Yan ◽  
Ji Song Bai ◽  
Xiong Zhou ◽  
Shun Hong Lin
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Wheat Straw ◽  
Bituminous Coal ◽  
Synergistic Effects ◽  
Order Reaction ◽  
Pyrolysis Process ◽  
First Order ◽  
Pyrolysis Characteristics ◽  
Apparent Kinetic Parameters

In this work, the pyrolysis behavior of bituminous coal (BC) wheat straw (WS) and the blends were investigated by thermogravimetric analysis. It was found that the main thermal degradation stage of BC and WS lies in different temperature range and there is nearly no overlapping. Interaction was observed during the co-pyrolysis process of BC and WS. At high temperatures, the volatile releasing is slightly inhibited by WS addition. Coats-Redfern method was used to analyze the apparent kinetic parameters. The results indicated that both the two reaction stages during pyrolysis process are well correlated by first-order reaction. The variation trend of activation energy value further confirm the synergistic effects between BC and WS. The experimental results may provide useful data for co-thermochemical utilization of biomass with coal.

Vulcanization Kinetics of Natural Rubber Coagulated by Microorganisms with Use of a Vulcameter

2010 ◽  
Vol 160-162 ◽  
pp. 1181-1186 ◽  
Author(s):  
Zhi Feng Wang ◽  
Si Dong Li ◽  
Xiao Dong She
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Rate Constants ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Second Stage ◽  
End Stage ◽  
Two Stages ◽  
Kinetics Of

Kinetics of vulcanization of natural rubber coagulated by microorganisms (NR-m) was studied with the use of a vulcameter. In the induction period of vulcanization, the time t0 of NR-m is shorter than that of natural rubber coagulated by acid (NR-a), and the rate constant k1/a of NR-m are greater than that of NR-a. Both the curing periods of NR-m and NR-a consist of two stages. The first stage follows first-order reaction. The rate constants k2 of NR-m in the first stage are greater than that of NR-a at the same temperature, and so are the activation energy E2. The second stage (end stage of the curing period) does not follow first-order reaction, and the calculated reaction order n of NR-m is in the range of 0.82-0.85, and that of NR-a is in the range of 0.64-0.72. The rate constants k3 of the second stage for NR -m are greater than that of NR-a at the same temperature, and so is the activation energy E3.

Kinetic Study on Lignin Extraction by Ionic Liquid

2013 ◽  
Vol 864-867 ◽  
pp. 477-481
Author(s):  
Yu Deng ◽  
Zhi Min Zhang
Keyword(s):  
Atmospheric Pressure ◽  
Black Liquor ◽  
Order Reaction ◽  
Pulp Yield ◽  
Residual Lignin ◽  
Yield Increase ◽  
First Order ◽  
Lignin Removal ◽  
Lignin Extraction ◽  
Cooking Temperature

This paper has studied the dynamics of delignification in ionic liquids pulping for straw at atmospheric pressure. The date showed that the concentration of the residual lignin in the pulp obviously decreased with the extension of steaming time, pulp yield increase, and the hexose and pentose content in the black liquor was gradually increasing, and at the same time, the amount of the hexose was higher than the pentyl. The concentration of the residual lignin reduced gradually with the cooking temperature increased,the pulp yield increase slowly. The lignin removal reaction is first order reaction, the activation energy is 42.117kJ/mol.

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