Pyrolysis Char Research Articles

Study on the thermal conversion characteristics of demineralized coal char under pressurized O2/H2O atmosphere

• Effects of H 2 O concentration/temperature/residence time on demineralized coal char's thermal conversion characteristics were investigated. • Quantitative analysis of the influence of experimental parameters on the change of char pore structure. • 900C is the key temperature for pressurized O 2 /H 2 O combustion. • The BET area of char prepared on different H 2 O concentration has a dominant effect on the reactivity. The pressurized O 2 /H 2 O combustion technology can achieve nearly zero CO 2 emissions during coal-fired power generation. In order to explore the influence of pressurized O 2 /H 2 O conditions on the thermal conversion characteristics of pulverized coal, Zhundong demineralized coal was used as raw material to prepare pyrolyzed char at 0.5 MPa and then the O 2 /H 2 O combustion experiments with different H 2 O concentration (0–40%), temperature (850-1000℃) and residence time (100–250 s) were carried out under the same pressure by a pressurized horizontal furnace. The carbon transformation, pore structure, carbon skeleton structure, and surface functional group structure of char under different experimental conditions were obtained by weighing method, Nitrogen adsorption test, Raman, and X-ray photoelectron spectroscopy methods, respectively. In addition, the reactivity of char was tested by thermogravimetric analyzer and micro fluidized bed reaction analyzer (MFBRA) to explore the relationship between the char structure and reactivity.

Studies on individual pyrolysis and co-pyrolysis of peat–biomass blends: Thermal decomposition behavior, possible synergism, product characteristic evaluations and kinetics

• The thermal decomposition data contains valuable information was analyzed. • Optimum experimental conditions of co-pyrolysis were determined. • The tar products derived from co-pyrolysis were characterized. • It is more reliable to calculate activation energy by the FWO and KAS methods. Chemical reaction engineering of pine branches and peat is crucial yet challenging in enhancing pyrolysis products quality for the synergistic effect and kinetic parameters distribution. Herein, the three-phase product yield and tar component distribution were studied through a series of characterization methods. Thermogravimetric analysis (TGA) data at different heating rates was obtained and synergistic effect in the CPBP were discussed. Through the three kinetic models to calculate the obtained TGA data and determine the kinetic parameters. The characteristics of mass loss from individual pyrolysis and co-pyrolysis registered in TGA during temperature programmed heating is attributed mainly to devolatilization of volatile fragments, and the heating rate and the mixing ratio of the samples experienced significant change on the weight loss. A weaker interaction in the process of co-pyrolysis of pine branches and peat (CPBP) is observed under the condition of multiple factors investigated in this work. The pyrolysis temperature is lower than 400 °C, the volatiles are not released in time, and remain in the pores of the pyrolysis char, which increases the yield difference of char. The relative abundance of the number of substituents in the monocyclic aromatic structure in tar is C3 < C0 < C1 < C2. The relative abundance of two methyl groups in the benzene series in tar exhibited the largest value, as indicated from GC–MS results. Conventional gas products such as H 2 O, CO 2 , CO, CH 4 and H 2 were detected. The activation energy was not a constant value, but changed with the progress of the reaction, indicating that the decomposition reaction mechanism changed as the reaction progressed. The activation energy and linear correlation determined using the KAS and FWO methods were higher. The aforementioned methods were more appropriate and reliable for the thermo-kinetics studies in CPBP.

In situ evolution of functional groups in char during cellulose pyrolysis under the catalysis of KCl and CaCl2

• An in situ and semi-quantitative analysis tool was proposed for char evolution. • The effects of chemical reactions and physical migration were separated. • The ‘char rearrangement’ of cellulose pyrolysis consists of four stages. • The climax stage after the DTG peak performed homogeneous devolatilization. • KCl and CaCl 2 altered the order of dehydration and ‘char devolatilization’. A combination of in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, perturbation-correlation moving-window two-dimensional correlation spectroscopy (PCMW2D) and two-dimensional correlation spectroscopy (2D-COS) was used to reveal the catalytic mechanism of KCl and CaCl 2 on cellulose char evolution during slow pyrolysis. Pretreatments of the one-dimensional spectra ensure the semi-quantitative analysis of the evolution of functional groups in pyrolysis char, which invoked principal component analysis followed by a Butterworth filter for denoising and extended multiplicative scatter correction. Through the differential processing of the absolute changes, the char evolution product was divided into ‘char rearrangement’ and ‘char devolatilization’ processes containing a high contribution from chemical reactions and physical migration, respectively. The ‘char rearrangement’ of cellulose pyrolysis consists of four stages, i.e. the budding, development, climax and decline stages, which were dominated by H-bond network reconfiguration, the consumption of C–O–C and OH, homogeneous devolatilization and aromatization, respectively. The uppermost influence of the two salts on the pyrolysis is the relationship alteration of C–O–C cleavage, dehydration reactions and ‘char devolatilization’. For neat, KCl-loaded and CaCl 2 -loaded cellulose, the unsaturated bonds were formed in the light reaction intermediate, heavy reaction intermediates and cellulose chain, respectively. Especially, the cleavage of most C–O–C following dehydration reactions conduced a shoulder peak in the differential thermogravimetry curve before the maximum weight loss rate of CaCl 2 -loaded sample. Due to the alteration, the pyrolysis was advanced but slowed down by the high content of unsaturated bonds in char. This study provides a powerful tool for the in situ semi-quantitative analysis of char evolution during the non-catalytic and catalytic thermo-chemical conversion of solid fuels and waste, and the results benefit to both biomass pyrolysis mechanism revelation and industrial production of biochar.

Study on CO2 gasification characteristics of pyrolysis char from pinewood block and pellet

Study on CO2 gasification characteristics of pyrolysis char from pinewood block and pellet

Biochar Amendments Improve Licorice (Glycyrrhiza uralensis Fisch.) Growth and Nutrient Uptake under Salt Stress.

Licorice (Glycyrrhiza uralensis Fisch.) is a salt and drought tolerant legume suitable for rehabilitating abandoned saline lands, especially in dry arid regions. We hypothesized that soil amended with maize-derived biochar might alleviate salt stress in licorice by improving its growth, nutrient acquisition, and root system adaptation. Experiments were designed to determine the effect of different biochar concentrations on licorice growth parameters, acquisition of C (carbon), nitrogen (N), and phosphorus (P) and on soil enzyme activities under saline and non-saline soil conditions. Pyrolysis char from maize (600 °C) was used at concentrations of 2% (B2), 4% (B4), and 6% (B6) for pot experiments. After 40 days, biochar improved the shoot and root biomass of licorice by 80 and 41% under saline soil conditions. However, B4 and B6 did not have a significant effect on shoot growth. Furthermore, increased nodule numbers of licorice grown at B4 amendment were observed under both non-saline and saline conditions. The root architectural traits, such as root length, surface area, project area, root volume, and nodulation traits, also significantly increased by biochar application at both B2 and B4. The concentrations of N and K in plant tissue increased under B2 and B4 amendments compared to the plants grown without biochar application. Moreover, the soil under saline conditions amended with biochar showed a positive effect on the activities of soil fluorescein diacetate hydrolase, proteases, and acid phosphomonoesterases. Overall, this study demonstrated the beneficial effects of maize-derived biochar on growth and nutrient uptake of licorice under saline soil conditions by improving nodule formation and root architecture, as well as soil enzyme activity.

Fast Pyrolysis as a Valorization Mechanism for Banana Rachis and Low‐Density Polyethylene Waste

AbstractBanana rachis and low‐density polyethylene (LDPE) were selected as secondary feedstocks for the study of fast pyrolysis in a free‐fall reactor. The experiments were performed at 600 °C for banana rachis and 450 °C for LDPE, based on literature and thermogravimetric analysis. The gaseous products of both feedstocks present similar composition in the C1–C2 compounds, while C3 compounds are only found in LDPE. The liquid products from banana and LDPE correspond to functional groups and shorter hydrocarbons, respectively. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) analyses of the char showed important morphological changes to spheres in LDPE and structural changes due to thermal decomposition in the biomass. The pyrolysis char has high potential as adsorbent, encapsulation, or catalyst.

Peach Seeds Pyrolysis Integrated into a Zero Waste Biorefinery: an Experimental Study

This study reports results of an experimental investigation of peach seeds for vegetable oils and biofuel production. Dry peach seeds have undergone hexane extraction for the recovery of oils/lipids and then pyrolyzed in a laboratory reactor. Pyrolysis parametric investigation was carried out to explore the effect of temperature, heating rate, and carrier gas flow on products’ yield. Energetic characterization of products was performed to assess them as biofuels, compared also with biofuels derived from other feedstocks. Results showed that pyrolysis temperature and heating rate played important role on yield and the composition of pyrolysis products. Extraction of oils/lipids reached 38.6 % wt., while pyrolysis gas, oil, and char yielded as 10–25, 37–50, and 10–20 % wt., respectively, at different pyrolysis conditions. Pyrolysis gas, bio-oil, and biochar HHVs estimated values were in the ranges of 10.5–28.5, 29–33, and 19.5–22.2 MJ/kg, respectively, all higher than that of lignite (19.3 MJ/kg). Sulfur content was not traceable in both solid and liquid products, while nitrogen content did not exceed 8.5% wt. The degree of linear association between pyrolysis parameters/variables and products’ yields and HHV was examined using the Pearson correlation coefficient. The results revealed that the cascade biorefinery approach applied for the valorization of peach seeds to produce oil/lipids and fuels, by sequential processing via hexane extraction and pyrolysis, can reach increased material and energy efficiencies varying from 73.5 to 93.7 % wt. and from 30.4 to 50 %, respectively. It can also increase the environmental and economic benefit of the agri-food sector while providing a green, closed loop, circular bioeconomy industrial practice.

Unmasking radical-mediated lignin pyrolysis after benzyl hydroxyl shielding

Whether lignin benzyl hydroxyl shielding could promote its pyrolysis to phenolic compounds was investigated in this paper. Lignin benzyl hydroxyl was first preoxidized by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and stabilized by propionaldehyde respectively, then pyrolysis was conducted with milled wood lignin as a control. Organic stable radicals in pyrolytic chars were further detected to reveal lignin pyrolysis chemistry. Results showed that benzyl hydroxyl shielding process weakened lignin thermal stability, and decreased liquid yields regardless of the frequency of lignin β-O-4 linkages. In addition, char yield grew after benzyl hydroxyl shielding. Radical concentration was inversely proportional to β-O-4 content which indicated the non-negligible impact of shielded benzyl hydroxyl on lignin pyrolysis. Furthermore, gases from propionaldehyde stabilized lignin quenched its radicals. This work confirmed that lignin β-O-4 linkages and shielded benzyl hydroxyl both played the great role in radical-mediated pyrolysis, but the enhancement of liquid products could not be achieved via benzyl hydroxyl shielding.

Effect of pyrolysis conditions on environmentally persistent free radicals (EPFRs) in biochar from co-pyrolysis of urea and cellulose

Biochar derived from nitrogen-rich pyrolysis of biomass can be used as a soil conditioner, but it contains a large amount of environmental persistent free radicals (EPFRs). EPFRs are a newly identified environmentally harmful substance, and the detection and research on EPFRs in nitrogen-rich pyrolyzed char is lacking. Biochars prepared from cellulose-urea mixtures at different temperatures, residence times, and urea ratios were analyzed in this study. EPFRs in biochar prepared at 500°C had the highest spin concentrations. Substituted aromatic compounds were the precursors to the EPFRs. The types of EPFRs in biochars shifted from oxygen-centered at 400°C to carbon- and oxygen-centered in the 450-600°C range due to a reduction in oxygen-containing functional groups. Residence time experiments showed that most EPFRs formed in the first 5min of pyrolysis. C was the main element used for the formation of EPFRs, while N content was negatively correlated with the concentration of EPFRs. Pyrolysis temperature was the key factor determining the types of EPFRs produced, while proportion of urea only affected the concentrations of EPFRs and not type. The results of this study are of great significance for understanding the environmental behavior of common EPFRs in nitrogen-rich biochar.

Co-gasification of petroleum coke with coal at high temperature: Effects of blending ratio and the catalyst

• Co-gasification of petroleum coke and coal chars at high temperature is studied. • The gasification reactivity is largely increased at blending ratio of 1:2. • Inhibited effect shows in early stage but synergistic effect in late stage. • NaAlO 2 significantly increases the reactivity at carbon conversion rate above 0.2. • Catalyst co-gasification largely reduces the final temperature from 1460 °C to 1150 °C. In this study, co-gasification and catalytic co-gasification of petroleum coke with coal at high temperature are studied. The structural characteristics of high temperature petroleum coke and bituminous coal pyrolysis char are compared, and the effects of blending ratio on the gasification reactivity and synergy are explored. The effect of catalyst on the co-gasification is also investigated. The results show that, high temperature petroleum coke shows a smoother surface morphology and has a higher degree of graphitization than the coal char, as a result, the gasification reactivity of the former is much lower than the latter. The coal char gasification process shows only one reaction stage, while the high temperature petroleum coke has two significant stages. The gasification reactivity of the blends increases with the coal blending ratio, and the largest increment is obtained when high temperature petroleum coke and coal char is blended at 1:2. As the co-gasification proceeds with the temperature, it first shows an inhibition effect, then gradually a synergistic effect. The temperature at which the synergistic effect appears decreases with the coal blending ratio increasing. However, the co-gasification reaction rate and reactivity get worse at carbon conversion rate large than 0.5, leading to a longer reaction time. When catalytic co-gasification, NaAlO 2 significantly increases the reactivity at carbon conversion rate larger than 0.2, and the temperature needed to finish the gasification for high temperature petroleum coke is reduced from 1460 °C to 1150 °C.

Effects of Parent Coal Properties on the Pyrolytic Char Chemical Structure: Insights from Micro-Raman Spectroscopy Based on 32 Kinds of Chinese Coals

The chemical structures of pyrolytic chars prepared from 32 kinds of Chinese coals were investigated with micro-Raman spectroscopy in this study. Both first-order and second-order Raman spectra of the chars were curve-fitted and analyzed. The effects of the parent coal properties, including coal rank, volatile, fixed carbon, and ash content, on the pyrolytic char structures were detailed discussed and the correlations between these coal properties and pyrolytic char chemical structures were set up. Multiple-factor analysis was done to propose a comprehensive coal property index that relates well to the pyrolytic char chemical structure. The results indicate that the aromatization degree is the key distinguishable structure of pyrolytic chars prepared from coals with various rank, and the alkyl C−H and aryl C−H structures have no significant difference. The aromatization degree of pyrolytic char decreases with the increase of coal rank, while it increases with the increase of the fixed carbon content in parent coals. The high content of moisture in parent coal can induce condensation of the pyrolytic char, but the inorganic composition probably prevents the condensation of the char. Limited correlations between the coal rank, fixed carbon, moisture and ash content, and the aromatization degree of pyrolytic chars were found. A comprehensive coal property index: (fixed carbon content + moisture content)/(volatile content + ash content) (in air dry basis) combining the coal properties together relates well to the aromatization degree of pyrolytic char and can act as a good indicator for the pyrolytic char chemical structure. This study reveals the effects of the parent coal properties, including coal rank, fixed carbon, moisture, and ash content, on the pyrolytic char chemical structure, and provides a new comprehensive coal property index to predict the pyrolytic char chemical structure.

Surface characteristics and electrochemical properties of activated carbon obtained from different parts of Pinus pinaster

Different parts (needle and cone) of the same biomass (pine, Pinus pinaster) were used as carbon source for activated carbon production. Biomass-derived activated carbons (ACs) were produced by the chemical activation of pyrolytic char. Dependence of the surface characteristics to the biomass type and activation agent were discussed by N2 Physisorption, Raman, and X-ray photoelectron spectroscopy (XPS) techniques. Pine-cone-derived ACs exhibit higher BET surface area and mesopore volume to micropore volume ratio compared to needle-derived ACs. Regardless of the biomass type, higher BET surface area and Vmes/Vmic ratio were obtained by KOH activation. XPS results proved that the KOH dominantly reacts with the aliphatic groups while H3PO4 reacts with aromatic groups during the activation. Hence, KOH activation led to the higher relative amounts of surface aromatic groups which will contribute to the total specific capacitance by creating pseudocapacitance. The electrochemical performance of the synthesized ACs was determined in packaged supercapacitors in CR2032 casings. Galvanostatic charge-discharge and self-discharge tests proved that all packaged supercapacitors displayed a repeatable cycle behavior and were highly stable. Cone-derived AC-based supercapacitors displayed higher specific capacitance than those of needle-derived ACs at all current densities (0.25–1 A/g). However, higher ESR values were observed for cone-derived AC based electrodes. The cone-derived AC (by KOH activation) based supercapacitor displayed 99% capacitance retention over 5000 cycles at 500 mA/g current density. It is found that the biomass type primarily affects the surface and electrochemical properties of ACs.

Experimental Analysis of Temperature Influence on Waste Tire Pyrolysis

Pyrolysis is an optimal thermochemical process for obtaining valuable products (char, oil, and gas) from waste tires. The preliminary research was done on the three groups of samples acquired by cutting the same waste tire of a passenger vehicle into cylindrical granules with a base diameter of 3, 7, and 11 mm. Each batch weighed 10 g. The heating rate was 14 °C/min, and the final pyrolysis temperature was 750 °C, with 90 s residence time. After the pyrolysis product yields were determined for all of the three sample groups, further research was performed only on 3 mm granules, with the same heating rate, but with altered final pyrolytic temperatures (400, 450, 500, 550, 600, 650, 700, and 750 °C). The results of this study show that thermochemical decomposition of the waste tire sample takes place in the temperature range of 200–500 °C, with three distinct phases of degradation. The highest yield of the pyrolytic oil was achieved at a temperature of 500 °C, but further heating of volatile matters reduced the oil yield, and simultaneously increased the yield of gas, due to the existence of secondary cracking reactions. The analysis of pyrolytic oil and char showed that these products can be used as fuel.

Co-oxidative removal of arsenite and tetracycline based on a heterogeneous Fenton-like reaction using iron nanoparticles-impregnated biochar

A highly efficient, eco-friendly and relatively low-cost catalyst is necessary to tackle bottlenecks in the treatment of industrial wastewater laden with heavy metals and antibiotic such as livestock farm and biogas liquids. This study investigated co-oxidative removal of arsenite (As(III)) and tetracycline (TC) by iron nanoparticles (Fe NP)-impregnated carbons based on heterogeneous Fenton-like reactions. The composites included Fe NP@biochar (BC), Fe NP@hydrochar (HC), and Fe NP@HC-derived pyrolysis char (HDPC). The functions of N and S atoms and the loading mass of the Fe NP in the Fe NP@BC in heterogeneous Fenton-like reactions were studied. To sustain its cost-effectiveness, the spent Fe NP@BC was regenerated using NaOH. Among the composites, the Fe NP@BC achieved an almost complete removal of As(III) and TC under optimized conditions (1.0g/L of dose; 10mM H2O2; pH 6; 4h of reaction; As(III): 50μM; TC: 50μM). The co-oxidative removal of As(III) and TC by the Fe NP@ BC was controlled by the synergistic interactions between the Fe NPs and the active N and S sites of the BC for generating reactive oxygen species (ROS). After four consecutive regeneration cycles, about 61 and 95% of As(III) and TC removal were attained. This implies that the spent carbocatalyst still has reasonable catalytic activities for reuse. Overall, this suggests that adding technological values to unused biochar as a carbocatalyst like Fe NP@BC was promising for co-oxidative removal of As(III) and TC from contaminated water.

Aging characteristics of asphalt binders modified with waste tire and plastic pyrolytic chars.

Globally, the growing volume of waste tires and plastics has posed significant concerns about their sustainable and economical disposal. Pyrolysis provides a way for effective treatment and management of these wastes, enabling recovery of energy and produces solid pyrolytic char as a by-product. The use of pyrolytic chars in asphalt binder modification has recently gained significant interest among researchers. As asphalt binder aging influences the cracking, rutting, and moisture damage performance of asphalt binder and the mixtures, evaluation of aging characteristics of char modified asphalt binders is quite important. The main objective of this study is the investigation of the aging characteristics of asphalt binders modified with waste tire pyrolytic char (TPC) and waste plastic pyrolytic char (PPC) through rheological and spectroscopic evaluations. To imitate short-term and long-term aging conditions, the asphalt binders were first treated in a rolling thin film oven (RTFO) and then in a pressure aging vessel (PAV). The aging characteristics were determined using four rheological aging indices based on complex modulus (G*), phase angle (δ), zero shear viscosity (ZSV), and non-recoverable creep compliance (Jnr) from multiple stress creep and recovery (MSCR) test. The fatigue cracking potential was then measured through binder yield energy test (BYET). These parameters were measured through a dynamic shear rheometer. Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H-NMR) spectroscopy analyses were then used to investigate changes in chemical composition due to aging in the char modified binders. Both TPC and PPC improved the high-temperature deformation resistance properties of asphalt binder. The TPC-modified binder showed better aging resistance than the control and PPC-modified binders, based on the different rheological and spectroscopic indices. The pyrolytic char modified binders also demonstrated good fatigue performance.

Prediction of char production from slow pyrolysis of lignocellulosic biomass using multiple nonlinear regression and artificial neural network

Char produced from lignocellulosic biomass via slow pyrolysis have become one of the most feasible alternatives that can partially replace the utilisation of fossil fuels for energy production. In this study, the relationship between compositions of lignocellulosic biomass, operating conditions of slow pyrolysis, and characteristics of produced char have been analysed by using multiple nonlinear regression (MnLR) and artificial neural networks (ANN). Six input variables (temperature, solid residence time, production capacity, particle size, and fixed carbon and ash content) and five responses (char yield, and fixed carbon, volatile matter, ash content, HHV of produced char) were selected. A total of 57 literature references with 393–422 datasets were used to determine the correlation and coefficient of determination (R2) between the input variables and responses. High correlation results (>0.5) existed between pyrolysis temperature and char yield (-0.502) and volatile matter of produced char (-0.619), ash content of feedstock and fixed carbon (-0.685), ash content (0.871) and HHV (-0.571) of produced char. Whilst the quadratic model was selected for the regression model, then the model was further optimised by eliminating any terms with p-values greater than 0.05. The optimised MnLR model results showed a reasonable prediction ability of char yield (R2 = 0.5579), fixed carbon (R2 = 0.7763), volatile matter (R2 = 0.5709), ash (R2 = 0.8613), and HHV (R2 = 0.5728). ANN model optimisation was carried out as the results showed “trainbr” training algorithm, 10 neurons in the hidden layer, and “tansig” and “purelin” transfer function in hidden and output layers, respectively. The optimised ANN models had higher accuracy than MnLR models with the R2 greater than 0.75, including 0.785 for char yield, 0.855 for fixed carbon, 0.752 for volatile matter, 0.951 for ash and 0.784 for HHV, respectively. The trained models can be used to predict and optimise the char production from slow pyrolysis of biomass without expensive experiments.

Evaluation of pyrochar and hydrochar derived activated carbons for biosorbent and supercapacitor materials

This study investigated effects of different thermal processes on characteristics of activated carbon to produce efficient biosorbents or supercapacitors using biomass resources. Pyrolysis char and hydrochar obtained from woody biomass were used as precursors for activated carbon under different atmospheric conditions (N2 and air). In order to provide functional groups on the carbon surface, activated carbon under N2 condition was subsequently acidified by HNO3 and the other was simultaneously acidified under air condition. Additionally, potential for application as Pb2+ adsorbent and supercapacitor was evaluated. Thermochemical behaviors such as bonding cleavage and dehydration during activation processes were observed by TG and Py-GCMS analysis. Elemental analysis, FT-IR, Raman spectroscopy, and XPS analysis were carried out to confirm changes in structures of each carbon products. New plausible reaction mechanism for this observation was suggested with respect to the formation of a key intermediate in the presence of excess air. As for performance in applications, air activated carbon using hydrochar exhibited high versatility to function as both Pb2+ adsorbent (~41.1mg/g) and energy storage material (~185.9F/g) with high specific surface area, mesopore ratio, surface functional groups.

Synergistic effect of co-pyrolysis of pre-dechlorination treated PVC residue and Pingshuo coal

Pyrolysis is an effective way for clean and efficient use of coal, as well as an important way for efficient conversion of waste plastics. A two-step treatment scheme was proposed for chlorine-containing plastics that are difficult to be treated harmlessly. Polyvinyl chloride (PVC) and Pingshuo (PS) coal were used in this study. The PVC was preheated to remove most of the chlorine, and then the pretreated PVC residue (DPVC) and coal were co-pyrolyzed. GC, simulated distillation, GC-MS, elemental analysis, FT-IR and Raman spectroscopy were used to analyze and characterize composition and properties of pyrolysis gas, tar and char. The results show that co-pyrolysis process of DPVC and PS coal has a synergistic effect, and has an obvious positive synergistic effect on formation of char and tar. The experimental value of tar yield is higher than theoretical calculation and the maximum increasing value is 3.35%. There is a negative synergistic effect on formation of pyrolysis water and gas, in which CH4 has the largest decrease in yield, meaning the strongest negative synergy. Co-pyrolysis increases content of light tar, significantly increases content of naphthalenes, and reduces that of asphalt. When DPVC addition is 10%, content of light tar increases by 5 percentage points over the theoretical calculation value. In addition, the co-pyrolysis char surface is smoother, its structure becomes more orderly, and graphitization degree increases.

Catalytic fast pyrolysis of beech wood lignin isolated by different biomass (pre)treatment processes: Organosolv, hydrothermal and enzymatic hydrolysis

• Lignin thermal pyrolysis oil exhibits similar S/G composition with solid lignins (2D HSQC NMR). • Catalytic upgrading of pyrolysis vapors with microporous ZSM-5 induces substantial deoxygenation/aromatization. • Mesoporous ZSM-5 enhances BTX (alkyl)aromatics without increasing further PAHs and coke formation. • Beech wood lignin isolation process has no significant effect on fast (catalytic) pyrolysis product yields and composition. Lignin is one of the three main structural components of lignocellulosic biomass and is considered as the most abundant source of aromatic and phenolic compounds. Lignin is produced as side-stream in the pulp/paper industry or as residue in the production of second-generation bioethanol. More recently, novel biomass fractionation processes in biorefineries have been developed aiming at the production of high quality/purity lignin towards its more efficient down-stream catalytic conversion to chemicals, monomers, and fuels. Within this context, in this work, we studied the thermal (non-catalytic) and catalytic fast pyrolysis on a Py/GC–MS system and a fixed-bed reactor unit of three types of lignin, all originating from the same biomass (beech wood sawdust) but with different isolation processes: organosolv lignin derived by the organosolv pretreatment/fractionation of biomass, surface extracted lignin derived by the mild Soxhlet extraction (with ethanol or acetone) from the hydrothermally (HT) in pure water pretreated biomass, and the enzymatic hydrolysis lignin derived as a lignin-rich solid residue from the enzymatic hydrolysis of the HT pretreated biomass. Conventional microporous ZSM-5 and mesoporous ZSM-5 zeolites (with intracrystal mesopores, ˜ 9 nm) were used as catalysts in the pyrolysis experiments. Both zeolites were very active in converting the initially produced via thermal pyrolysis methoxy-substituted phenols, benzenes and benzaldehydes mainly towards BTX mono-aromatics, such as 1,3-dimethylbenzene/p- and o-xylenes, toluene and trimethylbenzenes, as well as polycyclic aromatic hydrocarbons (PAHs, mainly naphthalenes). The mesoporous ZSM-5 induced higher dealkoxylation reactivity compared to the microporous ZSM-5 leading to higher concentration of BTX aromatics without a consequent increase of PAHs. The pronounced dealkoxylation/aromatization reactivity of both ZSM-5 zeolites resulted to lower yields (but highly aromatic) organic bio-oils (e.g. from 32−35 wt.% to 15−22 wt.%) compared to thermal pyrolysis, increased non-condensable gases (mainly CO, CO 2 , methane, ethylene and propylene) and formation of relatively low amounts of coke on catalysts (e.g. 3−5 wt.% on lignin) in addition to thermal pyrolysis char. The observed moderate variations in the characteristics of the three types of beech wood lignin, i.e. molecular weight (GPC), S/G ratio, inter-unit linkages (2D HSQC NMR) and elemental composition, did not induce a systematic/substantial differentiation in the thermal and catalytic fast pyrolysis product yields and composition.

Hierarchical Porous Catalytic Pyrolysis Char Derived from Oily Sludge for Enhanced Adsorption.

A novel pyrolysis char (PC), prepared by H3PO4 catalytic pyrolysis of oily sludge (OS), was presented to remove methylene blue (MB) dye from aqueous solution for the first time. The optimal preparation conditions (catalytic pyrolysis temperature of 411 °C, H3PO4 impregnation ratio of 2.44, and catalytic pyrolysis time of 59 min) were predicted by the response surface methodology. The optimal PC exhibited favorable hierarchical porous properties, which brought a large adsorption capability (322.89 mg/g). The adsorption process fitted well with the Langmuir model and pseudo-second order model. In addition, thermodynamic parameters showed that the adsorption process was endothermic (ΔH0 > 0) and spontaneous (ΔG0 < 0). The adsorption capability was strongly influenced by coexisting metal ions due to the competitive adsorption effect. The inhibition for MB adsorption was arranged in the following order: Al3+ > Fe3+ > Mg2+ > Ca2+ > K+ > Na+. The adsorption mechanism of MB onto the OS-derived PC includes pore filling, π–π interactions, and electrostatic interactions. The as-obtained PC adsorbent exhibited good reusability performance, which leads to great potential in practical application for wastewater treatment.