Pyrolysis Of Cotton Stalk Research Articles

Effect of bone char catalyst on the pyrolysis behavior and crystal structure of cotton stalks

This study investigated the characteristics of bone char (BC) in the in situ catalytic pyrolysis of cotton stalk (CS) using a fixed-bed pyrolysis system at 600 °C. The results revealed that BC contained abundant pore structures and polar active sites, which prolonged the residence time of gases and provided numerous reaction sites for the secondary reaction of pyrolysis products. At a CS-to-BC mass ratio of 1:2 (CB-1:2), the reaction rate was accelerated. As the BC proportion increased, the crystallinity of the char decreased, while the specific surface area increased. At CB-1:2, both the crystallite size and crystallinity of BC improved. The oxygen-containing functional groups in BC, such as CO32−, PO43−, −COOH, and −OH, effectively increased the adsorption active sites. Additionally, Ca2+ in BC promoted dehydrogenation, deoxidation, fused cyclization, and decarboxylation of carboxylic acids, leading to increased production of H2, CO, and CO2. Moreover, Ca2+ facilitated the homolytic reactions of lignin, generating hydrogen free radicals. These radicals reacted with methoxy radicals formed during lignin decomposition to produce methane.

Research on Catalytic Reaction of Cotton Straw Pyrolysis Based on Model Compounds

The study starts from the clean conversion of desulfurized ash and biomass resources, based on correlation analysis and Langmuir-Hinshelwood model, studies the components of cotton stalk pyrolysis products and describes the mechanism and effects of desulfurized ash as a catalyst in the pyrolysis process. Regression analysis, support vector machine, and other methods are used to predict the yield or output of pyrolysis products, which is of great significance for the efficient utilization and sustainable development of cotton stalks. The study found that desulfurized ash significantly promoted the thermal decomposition of cotton stalks, increased the pyrolysis gas yield and lower heating value, increased the production of hydrogen-rich gas in the pyrolysis gas, and reduced the production of carbon oxides. Through the study of model compounds, it was found that desulfurized ash has different catalytic effects on the process of cellulose and lignin components in cotton stalks generating pyrolysis gas.

Removing residual chlorine in water using carbon-based material derived from co-pyrolysis of cotton stalk and desulfurized ash

Herein, an environmentally friendly and low-caste absorbent has been studied to perform with high efficiency and fast removal rate of residual chlorine from wastewater. The chlorine removal absorbent was prepared in situ by co-pyrolysis of desulfurization ash (DA) and cotton stalk (CS) in a tube furnace at 600℃. Compared with CS pyrolysis alone, DA promoted the CS decomposition during co-pyrolysis of DA/CS. The maximum yield of pyrolysis gas was 188 mL/g with 11.33 MJ/Nm3, occurred in the DA/CS blending ratio of 50/100. Moreover, DA also catalyzed the well-developed micropore and mesoporous of cotton-stalk base carbon loaded with DA (CBCDA). The CBCDA with 38.62 wt% DA content had a pore volume of 0.0165 m3/g and a maximum specific surface area of 6.890 m²/g, which 1.96-fold and 1.50-fold higher than that of cotton-stalk base carbon, respectively. The further analysis of adsorption revealed that CaSO3 scattered on the surface of CBCDA fast and efficiently converted hypochlorite ion into chloride ion. The absorbent purified 90.02% residual chlorine from 12 mg/L wastewater within 30 min. Therefore, CBCDA absorbent offers a promising approach for fast and highly efficient purification of residual chlorine in wastewater.

Fractional condensation and aging of pyrolysis oil from cotton stalk

The current study is to investigate a multi-condenser system for separating pyrolytic vapors as a promoting method to produce bio-oils that are more impervious to aging. Bio-oil vapors produced by fast pyrolysis of cotton stalk in a fluidized bed reactor at a temperature of 500 °C and were divided by a fractional condensation system into four fractions. The results showed that the stability of the fractional bio-oil was improved because most of the reactive aliphatic compounds with small molecules involving water rich organic acids, aldehydes and ketones were effectively separated from the other components. It was found out that the stability of bio-oil was affected by the active chemicals derived from fast pyrolysis as well as the aqueous acidic condition of bio-oils because most polymerization, condensation and electrophilic addition substitution reactions need the presence of H+ to be the catalyst. The observation pointed out that the suspended solid particles (SS) in bio-oils can be suppressed by separating conventional bio-oils into different stages by means of concentrating the initial SS in a certain fraction.

Pyrolytic conversion of agricultural residue using continuous auger reactor for resource recovery

In this research work, agricultural residue was pyrolytically converted in a continuous semi pilot auger reactor. Studies have been carried out with variation in operating conditions such as temperature, and its effect on product yield and quality has been analyzed comprehensively. It was found that with increase in temperature from 400 to 500 ℃, the oil yield increased; however, reduced on further increasing the temperature. The char yield decreased from 50 to 20 wt% and gas yield increased with rising temperature. For cotton stalk pyrolysis, maximum biochar yield of 51% was obtained at 400 ℃, whereas maximum bio-oil yield of 46.5% was obtained at 500 ℃. Maximum gas yield of 55% was obtained with mustard husk feedstock at 700 ℃ temperature. Water content of the cotton stalk bio-oil (35%) was found to be lower than mustard husk bio-oil (79%). The water content in bio-oil was found to enhance with increase in temperature. GC-MS analysis confirmed that different chemical value compounds are present in the bio-oils obtained from both cotton stalk and mustard husk. In addition, the chars obtained had a calorific value of 24.15 MJ/kg for cotton stalk and 24.57 MJ/kg for mustard husk. At 500 °C, biochar showed good thermal stability in TGA analysis and major weight loss occurred in the temperature range of 500–600 ℃. It was also observed that biochar contains high amount of micronutrients and can be used for improving crop productivity by partially replacing synthetic fertilizers.

Experimental study on cotton stalk pyrolysis tar degradation by oxidation in combination with K-containing semi-coke

The concept of using partial oxidation coupling with K semi-coke to decompose tar is presented in this research as a way to increase tar energy recovery. According to the results of the partial oxidation of cotton stalk tar, the oxidation accelerated tar cracking and increased CO production as H2 was consumed. The CO content in the gas can reach a maximum of 38 % when the oxygen flow rate is 12.5 mL/min, and the mixture's calorific value can reach 12.5 MJ/Nm3. When tar components are oxidized, the oxygen-containing ones that have a higher activity are more quickly converted into aromatic compounds. Toluene was chosen as the representative compound of oxidized tar, and cotton stalk semi-catalytic coke's properties in the heterogeneous degradation of toluene with or without the presence of K were contrasted. The results reveal that K is easily combined with the oxygen-containing active groups (CO, CO, OH) of semi-coke to boost their activity, resulting in more basic adsorption sites on the semi-coke surface, which strengthens toluene adsorption and accelerates the cracking of the toluene benzene ring and the generation of aliphatic hydrocarbons. The specific surface area and pore development of the semi-coke with K addition were greater than the semi-coke without K addition, which improved the toluene's degradation and condensation reaction while also increasing the amount of carbon on the semi-surface coke's area.

Catalytic pyrolysis of cotton stalk to produce aromatic hydrocarbons over Fe modified CaO catalysts and ZSM-5

In this study, a novel method for the enhanced production of aromatic hydrocarbons by biomass pyrolysis with Fe modified CaO and ZSM-5 was proposed. The feasibility of aforementioned method and related reaction mechanism for the formation of aromatic hydrocarbons were investigated in Py-GC/MS. The results showed that Fe modification of CaO increased its specific surface area and generated Ca2Fe2O5. As a result, 5Fe/CaO and 10Fe/CaO (CaO modification by 5 wt% and 10 wt% Fe, respectively) promoted the cracking of lignin oligomer to phenols, ketonization of acetic acid to acetone, and dehydration of levoglucosan to furfural. Therefore, the addition of 5Fe/CaO or 10Fe/CaO in cotton stalk catalytic pyrolysis with ZSM-5 favored the formation of BTX obviously. The peak area % of BTX obtained by dual-catalyst of 10Fe/CaO and ZSM-5 can reached up to 67.5%, boosting 10.94% and 2.94% than ZSM-5 alone and dual-catalyst of CaO and ZSM-5, respectively. Meanwhile, the peak area of BTX obtained by dual-catalyst of 5Fe/CaO and ZSM-5 boosts 9.59% and 7.11% than ZSM-5 alone and the dual-catalyst of CaO and ZSM-5, respectively.

Influence of calcination temperature on calcined carbide slag assisted biomass pyrolysis

Biomass pyrolysis over CaO produced from the calcination of precursors is a prospective method for upgrading pyrolysis products while also lowering CO2 emissions. However, the structure-activity relationship of CaO in biomass pyrolysis process is rarely reported. In this study, cotton stalk pyrolysis over CaO produced from carbide slag was conducted, and the effect of calcination temperature (650–950 °C) on the structure of CaO and its performance in biomass pyrolysis process was thoroughly explored. Results showed that decreasing the calcination temperature would inhibit the sintering of CaO crystals, and thus CaO obtained at low calcination temperature (650 °C) showed small crystal size (43 nm) and strong basicity, resulting in a high CO2 fixation (0.146 g/g CaO) and LHV of pyrolysis gas (18.95 MJ/m3). Meanwhile, with the calcination temperature increasing from 650 °C to 950 °C, the content of acids in bio-oil increased significantly from 17.89% to 32.30%, and that of hydrocarbons in bio-oil decreased noticeably from 11.47% to 5.21%, indicating the decrease of bio-oil quality. Overall, the calcination temperature of 650 °C is more favorable for CO2 fixation and pyrolysis products upgrading.

Understanding pyrolysis mechanisms of corn and cotton stalks via kinetics and thermodynamics

The kinetics and thermodynamics of biomass pyrolysis are crucial in its design, optimization and industrial application. The physicochemical characterization, kinetic and thermodynamic analyses of corn and cotton stalks pyrolysis are performed. Nonisothermal thermogravimetric analysis (TGA) with four heating rates (4, 8, 16 and 32 K min−1) is employed to experimentally investigate their pyrolysis kinetic behaviors. The effective activation energy values obtained by isoconversional kinetic analysis vary significantly with the reacted fraction and the average values are 206.2 and 207.4 kJ mol−1 for the pyrolysis of corn and cotton stalks, respectively. The changes in Gibbs free energy, enthalpy and entropy for them are evaluated and the results indicate that corn and cotton stalks pyrolysis is nonspontaneous processes and requires external energy to be thermally decomposed and that their endothermicity and reactivity increase as their pyrolysis processes proceed. The results can be helpful in better understanding the reaction mechanisms and extending the application of corn and cotton stalk pyrolysis.

Characteristics of bio-oil and biochar from cotton stalk pyrolysis: Effects of torrefaction temperature and duration in an ammonia environment

In this study, nitrogen-containing chemicals and nitrogen-rich biochar were prepared using ammonia (NH3) torrefaction pretreatment technology. The effects of temperature and duration of torrefaction on the characteristics of torrefaction and pyrolysis products were evaluated. The results indicated that when the torrefaction temperature was increased to 290 °C, the nitrogen content increased significantly from 0.98% to 6.85%. XPS analysis showed that the raw biomass mainly contained amide-N and pyrrole-N. As the torrefaction temperature and duration increased, quaternary-N formation was promoted, while amide-N, pyrrole-N, and pyridine-N were consumed. Potential nitrogen doping and transformation pathways during the ammonia torrefaction process were proposed. GC–MS analysis showed that ammonia torrefaction promoted the formation of pyridines, while reducing the content of oxygen-containing species. In addition, torrefaction duration had positive effects on the yield of nitrogen-containing chemicals.

Characterization and kinetic modeling for pyrolytic conversion of cotton stalks

AbstractHerein, cotton stalk biomass was initially characterized to understand its physicochemical properties as a raw material for biochar production. Furthermore, thermal analysis was conducted using thermogravimetric analysis (TGA), and the results were further utilized to evaluate the cotton stalk's kinetic behavior under thermal decomposition in an inert environment. Advanced kinetics and technology solutions (AKTS) software was for the first time employed to compute the kinetic parameters of cotton stalk pyrolysis, as well as provide kinetic predictions under isothermal conditions. Three methods were used to compute the activation energy (Ea) value, namely ASTM‐E698, Flynn‐Wall‐Ozawa (FWO), and Friedman's differential iso‐conversional model. The results obtained using the ASTM‐E698 method indicate an activation energy of 127.23 kJ·mol−1. Furthermore, the FWO method presented an Ea value ranging 35‐250 kJ·mol−1. The differential iso‐conversional method is the most robust approach as it adequately represents the complex nature of lignocellulosic biomass decomposition, showing an Ea range between 4 and 250 kJ·mol−1. Based on the differential iso‐conversional method, kinetic predictions under isothermal conditions were provided. The predictions offer valuable insight for industrial‐scale biochar project developers in relation to production throughput optimization. Furthermore, the kinetic parameters obtained can be utilized in process modeling.

Kinetics of pyrolysis of cotton stalk using model-fitting and model-free methods

With the depletion of fossil fuels, the conversion of biomass to biofuel is increasingly seen as a possible solution. Pyrolysis is one of these biomass-to-biofuel conversion technologies. In the present study, cotton stalk pyrolysis was investigated to determine the intrinsic kinetic parameters to understand the pyrolysis process. Model-fitting and model-free methods are applied to assess the kinetics. Pyrolysis of the cotton stalk was performed at different heating rates (10, 20, 30, and 40 K min−1) using a thermogravimetric analyzer. The obtained data from TGA was used to estimate the key kinetic parameters using various models/methods including Single reaction model, Series reaction model, Kissinger-Akahira-Sunose (KAS) method, and Flynn–Wall–Ozawa (FWO) method. The results of model-fitting kinetics showed that the pyrolysis mechanism could not be explained by the simple reaction models and obtained unrealistic kinetic parameters. Further, model-free methods were investigated to address the complex reaction mechanism. Besides, the predicted activation energy using KAS method values ranged from 223 to 230 kJ mol−1. In the FWO method, activation energy ranges from 213 to 240 kJ mol−1. In both methods, the calculated average activation energy value is in the proximity of 226 kJ mol−1 for fractional conversion value of 0.05 > α > 0.7.

Formation mechanism of aromatics during co-pyrolysis of coal and cotton stalk

Pyrolysis experiments were conducted in a tubular furnace from room temperature to 600 °C at 5 °C /min, and kept for 15 min. The light tar was then derived from the liquid products of pyrolysis by n-hexane supersonic extraction. Gas chromatography–mass spectrometry was employed to analyze the light tars from cotton stalk (CS) pyrolysis, Shenmu coal (SM) pyrolysis, and co-pyrolysis of CS/SM. Microcrystalline cellulose (MCC) was selected as a model compound, and the light tar from co-pyrolysis tar of MCC/SM was investigated for comparison. The results indicated that CS improved the yields and quality of phenols and benzenes in co-pyrolysis tar and that MCC had excellent performance in the formation of mononuclear aromatics during the co-pyrolysis of MCC/SM. Based on the pyrolytic behavior of CS and SM, the mechanisms of aromatic formation were further determined. It was shown that the free radicals that cracked from CS accelerated the formation of aromatics. The alkyl and mononuclear aromatic radicals of CS pyrolysis combined with the radicals from the SM aromatic structure, which then converted to benzenes and phenols. Finally, the most favorable reaction routes of mononuclear aromatics formation were proposed.

Pyrolytic carbonaceous reinforcements for enhanced electromagnetic and fracture response of cementitious composites

Rising amounts of cotton-crop residue and waste scrap tires are potential environmental challenges and poses serious health hazards on discarding as landfill materials or burning as fuel. This waste has been successively converted into nano-carbonaceous reinforcements with their explored potential in the fabrication of multipurpose concrete. Initially, bio-char was prepared via pyrolysis of cotton stalk and waste tire at 500 °C in nitrogen atmosphere followed by its milling into nano/micro phase. The synthesized nano particles were added in cementitious mortar specimens in 0, 0.025, 0.05, 0.08, 0.2, 0.5 and 1.0% by weight of cement to explore the effect of their added content on electromagnetic shielding and fracture toughness of cementitious composites.It was resolved experimentally that effortlessly uniform dispersion of nano/micro inerts in mixing water and host matrix were accomplished that effectively produced interfacial polarization which contributed in significant improvement of electromagnetic-interference shielding by 22.9 db and 24.2 db on 0.5% optimum addition of carbonized cotton stalk and carbonized waste tire respectively. Besides, packing effects of nano/micro inerts intrusion in cementitious composites reduced the porosity. Moreover, crack pinning and deflection are the phenomenon which resulted in more ductile rupture of specimens with 59.7% and 48.8% enhancement in fracture toughness on 1.0% addition of carbonized cotton stalk and carbonized waste tire respectively.

Solar pyrolysis of cotton stalk in molten salt for bio-fuel production

Solar pyrolysis of cotton stalk was carried out in a molten salt reactor heated by 4 kW solar simulator. The effects of pyrolysis temperature and mass ratio of molten salt to biomass on pyrolysis products properties were investigated. The use of molten salt as pyrolysis media increased gas yield. At 850 °C, the gas yield (mainly of CO and H2) continued to rise from 41.35 wt% to 82.57 wt% when mass ratio of molten salt to cotton stalk increased from 0 to 10. Pyrolysis in molten salt significantly decreased bio-oil acids and phenols, while increased aromatics among pyrolysis temperature range of 450–850 °C. There was positive correlation between the increased content of aromatics and mass ratio of molten salt to cotton stalk (from 0.5 to 10). The bio-char carbon content showed a general decreasing trend while oxygen, BET surface area and pore volume increased with using molten salt as pyrolysis media. Bio-char obtained from CS1MS5 pyrolysis at 850 °C had the highest BET surface area of 972.57 m2/g and the biggest total pore volume of 0.6203 cm3/g. High quality pyrolysis products with more uniform chemistry suggest catalytic reactions occur inside the solar reactor due to the intermediates degradation with molten salt.

Co-pyrolysis of cotton stalk and waste tire with a focus on liquid yield quantity and quality

In this study, effect of waste tire (WT) addition to cotton stalk (CS) pyrolysis is investigated with a focus on liquid co-pyrolysis yield quantity and quality. Various blend ratios (i.e. CS/WT 1:0, 4:1, 3:2, 2:3, 0:1) of the two feedstocks were experimented in a fixed bed reactor at 20 °C/min heating ramp rate up to 550 °C with 50 ml/min flowrate of nitrogen as sweeping gas. Blend ratio CS/WT (2:3) showed maximum oil yield (48 wt%) with organic phase (OP) above 78 wt% of the total liquid yield (OP + aqueous phase, AP). OP of CS/WT (2:3) along with those of CS/WT (1:0) and (0:1) were further analyzed qualitatively using analytical techniques including, FTIR, GC-MS, bomb calorimetry and elemental analyzer. Significant increase in carbon and decrease in oxygen content of the CS/WT (2:3) pyrolytic oil was observed which improved its calorific value to 41 MJ/kg. Among the three OP samples, only CS/WT (2:3) oil showed significant presence of alkanes in GC-MS results, which is, thus, associated with the synergistic effect of the co-pyrolysis process. Addition of WT to CS pyrolysis feedstock improved liquid yield and its quality, thus requiring lesser further processing for its commercial use as compared to that of CS/WT (1:0) oil.

Influence of torrefaction with Mg-based additives on the pyrolysis of cotton stalk

The study presented an approach to introduce Mg-based additives into cotton stalk for strengthening deoxygenation effect during torrefaction. Then catalytic pyrolysis of torrefied feedstock with Mg-based additives residue as catalyst was performed at 550 °C for 10 min in a fixed-bed reactor. The effects of torrefaction temperature (200, 230, 260, 290, 320, 350 °C), type of Mg-based additive (MgO and MgO-K2CO3), mass ratio of additive to biomass (0.5, 1 and 2) on pyrolysis were investigated. The results indicated that yields of bio-char and bio-oil significantly increased and decreased with torrefaction temperature rising to 350 °C. MgO inhibited pyrolysis bio-char yield increase with torrefaction severity. MgO-K2CO3 increased H2 yield a lot from 1.39 to 3.67 mmol/g. It also effectively improved the aromatic hydrocarbons in bio-oil and the reduction of acids. A maximum aromatic hydrocarbons yield of 16.05% was obtained with MgO-K2CO3 (the mass ratio of 0.5:1) at torrefaction temperature of 320 °C.

An approach for upgrading biomass and pyrolysis product quality using a combination of aqueous phase bio-oil washing and torrefaction pretreatment

Bio-oil undergoes phase separation because of poor stability. Practical application of aqueous phase bio-oil is challenging. In this study, a novel approach that combines aqueous phase bio-oil washing and torrefaction pretreatment was used to upgrade the biomass and pyrolysis product quality. The effects of individual and combined pretreatments on cotton stalk pyrolysis were studied using TG-FTIR and a fixed bed reactor. The results showed that the aqueous phase bio-oil washing pretreatment removed metals and resolved the two pyrolysis peaks in the DTG curve. Importantly, it increased the bio-oil yield and improved the pyrolysis product quality. For example, the water and acid content of bio-oil decreased significantly along with an increase in phenol formation, and the heating value of non-condensable gases improved, and these were more pronounced when combined with torrefaction pretreatment. Therefore, the combined pretreatment is a promising method, which would contribute to the development of polygeneration pyrolysis technology.

Optimizing the Conditions for the Microwave-Assisted Pyrolysis of Cotton Stalk for Bio-Oil Production Using Response Surface Methodology

In this study, the Box-Behnken design response surface methodology was applied to investigate the optimum conditions for pyrolysis of cotton stalk using microwave-assisted pyrolysis system. Three operating variables, namely microwave power (W), reaction temperature (°C) and reaction time (min) with a total of 17 individual experiments were conducted to optimize the combination effects of the variables. The optimal liquefaction conditions were estimated as: the microwave power of 1800 W, the reaction time of 24 min, the reaction temperature of 550 °C with the highest bio-oil yield of 32.47 %. In addition the obtained bio-oils were confirmed mainly contained phenols and benzene carboxylic acid through GC–MS analysis.

Effects of acid and metal salt additives on product characteristics of biomass microwave pyrolysis

To study the influence of additives on the pyrolysis behavior of microwave-heated biomass, cotton stalk pyrolysis was performed using both a particular microwave pyrolysis reactor and an electric heating system with the addition of acid (H3PO4) and metal salts (NaCl, K2CO3, and MgCl2) at 550 °C. The derived products were evaluated by environmental scanning electron microscopy, gas chromatography with mass spectrometric detection, and temperature adsorption analysis. The results indicated that microwave heating with additives was beneficial to enhance the quality of the pyrolysis products. The addition of H3PO4 was favorable for liquid oil formation with higher furfural and acetic acid contents. The highest yield of oil was achieved with 8% H3PO4, while the maximum char yield and surface area were obtained at 12% H3PO4, as higher percentages caused the formation of more porous solid char. The addition of metal salts promoted the formation of char at the cost of decreasing the liquid oil production. The maximum yields of bio-oil and char were achieved with the addition of MgCl2, while the minimum yields were obtained by adding K2CO3. The addition of MgCl2 (8%) promoted the formation and pore growth of char during the pyrolysis process; moreover, it was helpful for the production of furfural and acetic acid substances as well as a small amount of naphthalene. The addition of K2CO3 (8%) increased the gas production significantly but decreased the specific surface area of char. The addition of NaCl (8%) increased the char yield but decreased the oil and gas yields slightly. The comparative results showed that microwave pyrolysis with H3PO4 and MgCl2 additives were beneficial for the preparation of activated char with a large specific surface area and optimal formation of bio-oil.