Properties Of Pyrolysis Products Research Articles

Pyrolysis of Latex Sediment from Concentrated Latex Industry and Properties of Pyrolytic Products

Concentrated latex is an intermediate rubber product in Thailand. It is an important industry that generates income for the country and Its southern region. The main products of the latex factory were concentrated latex and skim blocks. The industrial waste from the concentrated latex factory is called latex sediment. It appears to be a white mixed light-yellow sludge or a dark brown color, contains magnesium compounds, and phosphorus is an important element. Therefore, finding appropriate measures for rubber production and environmentally friendly industrial waste management is important. Therefore, this study investigates the pyrolysis of latex sediment as an alternative to industrial waste management. Pyrolysis of 100 g of latex sediment was performed at 300 °C, 500 °C, and 700 °C. From the experiment, it was found that the properties of the liquid product from the pyrolysis process at 500 °C were alkaline, with a pH of 9.45. However, acetic acid was the highest amount of organic substance in the liquid product. Substances in the amine and amide groups were also observed, a base result for the liquid product exhibiting an alkaline value. The pH is an important factor in the decomposition of organic substances under anaerobic conditions. Therefore, a 1 wt% liquid product was used in a volume of 13.5 mL, which is the most appropriate amount because it uses the least amount of liquid product to adjust the alkalinity of the skim latex serum before entering the anaerobic fermentation system. Pyrolysis is an environmentally friendly option for managing factory latex sediments for sustainable production and creating a good image for the organization.

The Application of Pyrolysis Biochar Obtained from Waste Rapeseed Cake to Remove Copper from Industrial Wastewater: An Overview

Pyrolysis is a thermochemical technology for converting biomass into energy and chemical products consisting of bio-gas, bio-oil, and biochar. Several parameters influence the process efficiency and properties of pyrolysis products. These include the type of biomass, biomass preliminary preparation, gaseous atmosphere, final temperature, heating rate, and process time. This manuscript provides a general summary of the properties of the pyrolytic products of waste rapeseed cake, with particular emphasis on the sorption properties of biochar. Biochar, produced by the pyrolysis process of biomass, is emerging as a powerful tool for carbon sequestration, reducing greenhouse gas emissions, and purifying water from contaminants such as potentially toxic elements and antibiotics. The review found that the biochar obtained as a result of pyrolysis of chemically modified waste rapeseed cake is characterised by its excellent sorption properties. The obtained sorbents are characterised by sorption capacity relative to the copper(II) ion, ranging from 40 mg·g−1 to 100 mg·g−1, according to the pyrolysis conditions and chemical modification method. The purified pyrolysis gas obtained in the high-temperature process can be used to generate heat and energy. Bio-oil, with its significant combustion heat of 36 MJ·kg−1, can be a source of environmentally friendly green biofuel.

Characteristics of the pyrolytic products and the pollutant emissions at different operating stages from a pilot waste tire pyrolysis furnace

Pyrolysis is considered a highly practical, cost-effective, and environment-friendly technology for waste tires disposal. In this study, pyrolysis processes of waste tires were conducted in a pilot scale furnace feeding at 30 kg/h. The properties of pyrolytic products and the distribution patterns of pollutants generated in different operating stages (start-up, steady, and shut-down) were investigated. The pyrolytic gas in the steady state had a high caloric value of 10799 kJ/Nm3, valuable as heating source for pyrolysis. The elements of sulfur and zinc were effectively fixed as ZnS in the pyrolytic carbon. The basic properties of pyrolytic oil were in line with commercial diesel oil except for the lower flash point. Heavy metals were mainly concentrated in the pyrolytic carbon, with slightly higher concentrations in the steady state. Moreover, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were mainly concentrated in the pyrolytic oil, with predominated low-ring PAHs and high chlorinated PCDD/Fs. The concentrations of PAHs and PCDD/Fs in the gas phase were higher during the start-up stage due to the memory effect, whereas were effectively reduced during the steady stage. The concentration of PAHs in the solid phase was highest during the furnace start-up and lowest in the shut-down stage. In contrast to PAHs, the PCDD/Fs in the solid phase reached their highest concentration during the shut-down stage, which was mainly affected by temperature. The results provide guidance for the reducing of pollutant emissions and the recycling of pyrolytic products.

Research on the application of catalytic materials in biomass pyrolysis

Biomass, as a very important renewable resource, its efficient conversion was an important way to achieve zero CO2 emissions, provide clean and renewable energy, and promote the resource utilization of agricultural waste. Biomass pyrolysis, as a technology that could simultaneously obtain high value-added energy and chemical products such as biochar, bio-oil, and combustible gas, had received widespread attention, in which the role of catalysts in biomass pyrolysis had also been widely studied. In this thesis, the application of catalysts in biomass pyrolysis was reviewed in detail on the basis of introducing the principle and pyrolysis methods of biomass pyrolysis, and found that catalysts could effectively improve the distribution and properties of pyrolysis products, especially for the reforming of bio-oil and bio-gas, which had shown outstanding performance in green energy and functional chemicals. At the same time, the current problems of catalysts in biomass pyrolysis were analyzed, and new thoughts were proposed for future research on biomass catalytic pyrolysis, with a view to providing new ways for efficient catalytic pyrolysis and green sustainable development of biomass.

Studies on the Migration of Sulphur and Chlorine in the Pyrolysis Products of Floor and Furniture Joinery

This article discusses research on the low-temperature pyrolysis of waste floor and furniture joinery as an example of chemical recycling. Pyrolysis was carried out at 425 °C to obtain solid, liquid, and gaseous products. In line with the circular economy concept, the waste was transformed into economical and environmentally friendly raw materials suitable for application. Research results related to the chemical composition and properties of pyrolysis products are shown, with particular emphasis on the migration process of acidic impurities, i.e., sulphur and chlorine. In some processes, the presence of such substances can be a problem. Research has shown the high potential for sulphur and chlorine migration in pyrolysis products. It was shown that for woodwork, the most sulphur was discharged with the pyrolysis gas and the least was immobilised in the oil fraction. For vinyl panels, more than 50% of the sulphur was immobilised in the char. Chlorine was immobilised mainly in the char and pyrolysis gas. A high chlorine content of 12.55% was found in the vinyl panel. At the same time, a high chlorine content was also found in the pyrolysis products of these panels. This value is several times higher than in wood-based waste.

Bromine Migration and Product Analysis of Waste Printed Circuit Boards during Microwave Steam‐Gasification‐Assisted Pyrolysis

AbstractBromine in waste printed circuit boards has caused serious harm to the environment. How to deal with it safely is a problem. In this paper, the debromination of waste printed circuit boards by microwave gasification pyrolysis was studied, and the properties of pyrolysis products and the migration of bromine were analyzed. The optimum pyrolysis conditions of microwave steam atmosphere were 600 °C, 1000 W, 50 min, 2 mL/min. Compared with conventional pyrolysis and conventional steam pyrolysis, less solid products (60.39 wt %) were obtained, and more metal copper was enriched. The content increased from 27.46 % and 28.35 % to 30.63 %, respectively, and the diffraction peak intensity of copper was also enhanced. There is no obvious change in the type of functional groups of the solid product, and its microscopic morphology is smoother. Compared with conventional pyrolysis, the phenolic compounds in pyrolysis oil decreased, and increased compared with conventional steam pyrolysis. The content of H2 in the pyrolysis gas increased significantly, and the content of CO decreased significantly. Compared with conventional pyrolysis, the bromine content in pyrolysis gas and pyrolysis oil decreased from 94.5 % and 5.5 % to 1 %, respectively, and more bromine (98 %) in the raw material entered the aqueous solution.

Cross-interaction of volatiles in co-pyrolysis of spinach and noodles and their impacts on properties of pyrolytic products and pyrolysis kinetics

Noodles and spinach are common staple food and vegetables in kitchen waste and they have distinct compositions. Their co-pyrolysis might induce some cross-interactions in terms of volatiles-volatiles or volatiles-biochar, the influence of which on properties of pyrolytic products was studied herein in co-pyrolysis of noodles and spinach at 600 °C. The results indicated that the abundance of inorganics (contained elements such as K, Ca, Na and Cl) in spinach promoted cracking of volatiles, producing more gases at the expense of bio-oil. The inorganics from spinach also promoted further cracking of volatiles from the noodles in the co-pyrolysis, diminishing production of bio-oil. Additionally, cross-polymerization of the volatiles also occurred in the co-pyrolysis, generating oxygen-rich biochar with lower thermal stability but a much higher hydrophilicity. The in-situ Diffuse Reflection Infrared Fourier Transform Spectra (DRIFTS) measurement showed that the inorganics in spinach catalyzed the cracking of aliphatic structures in biochar and hindered aromatization process, leading to the especially low C content of biochar. The kinetic study showed that the co-pyrolysis of noodles and spinach reduced activation energy for conversion of the feedstock, originating from the cross-interactions among the volatiles and between the volatiles and biochar of different origin.

Thermo-chemical behaviour of maize cob and bean straw briquettes

• Pyrolysis of maize cob and bean straw briquettes were studied. • Briquetting conditions had no impact on thermos-chemical behaviour. • Temperature had the dominant effect on yields and properties of pyrolysis products. • Pyrolysis of briquettes was suited to maximise the production of char. • Up to 45% energy content was stored in smokeless char like material. Pre-treatment is essential to reduce logistic costs of agricultural residues. This work examined the interactions between pre-treatment conditions and thermo-chemical behaviour on product yields and properties. The effect of pyrolysis operating and briquetting conditions (i.e., temperature, pressure and bean straw-maize cob blend) on yields and properties of pyrolysis products from maize cob, bean straw and blended briquettes were investigated. It was found that briquetting conditions, heating rate and carrier gas flow rate had negligible effects on yields and properties of pyrolysis products. Temperature was the dominant factor that effected the yield and properties of the pyrolysis products. Increasing pyrolysis temperature increased the gas and reduced the char yield. Up to ∼45% of the energy content of the raw material can be stored in smokeless char like material that can be easily transported and used for energy production e.g., household cooking. Pyrolysis of agricultural residues has the potential to reduce harmful particulate emissions whereas the high-water content bio-oil can be used as a binder in briquette production to reduce the pressure and temperature applied.

A state‐of‐the‐art review of the fate of heavy metals and product properties from pyrolysis of heavy‐metal(loid)‐enriched biomass harvested from phytoextraction

AbstractVegetation has successfully been used for cleaning up metal(loid) polluted water bodies and lands through extracting and accumulating of contaminants in their aboveground biomass (phytoextraction). As this remediation technique is approaching extensive demonstration scale application and potential commercialisation, research efforts have been investigating new ways to achieve valorization of its by‐products, the heavy‐metal‐enriched biomass (HMEB). Biomass pyrolysis as an energy conversion technique represents a key step to numerous valorization options of HMEB. During the pyrolysis of HMEB, understanding the thermal decomposition pathways, and the migration and transformation of metal(loid)s are critical for the production of clean, safe and value‐added end‐products. This work performs a state‐of‐the‐art review of the studies conducted on phytoextraction and biomass pyrolysis of HMEB with emphasis on the properties of pyrolysis products as well as the behavior of heavy metal(loid)s during pyrolysis in relation to HMEB feedstock properties and the variables of the process.

Impacts of temperature on hydrophilicity/functionalities of char and evolution of bio-oil/gas in pyrolysis of pig manure

Pig manure is a carbonaceous waste and has a distinct composition with biomass and the pyrolysis products properties could also be different. In this study, particular attention was paid on the evolution of functionalities and the changes of hydrophobicity/hydrophilicity of char with an increase in temperature, as these surface properties determine the applications of char as support of catalyst or adsorbent. Our results demonstrated that both oxygen and nitrogen-containing organic species in manure were thermally unstable, decomposition of which initiated from 200 °C and proceeded to near completion at 600 °C. The substantial deoxygenation at 300–500 °C did not result in the proportional increase of carbon content of char, as the carbonization did not take place effectively. Instead, the excessive cracking of these organic species made the inorganic SiO2 and CaCO3 as the dominant species in the char formed at high temperatures. The abundant oxygen-containing functionalities in the char produced via pyrolysis below 300 °C could not be sufficiently exposed, leading to the high hydrophobicity of char. In comparison, the exposure of the inorganic species in the char produced at high pyrolysis temperature made char more hydrophilic, which, however, was not favorable for the dispersion of metallic nickel species in the Ni/char catalyst.

Changes in caking properties of caking bituminous coals during low-temperature pyrolysis process

We proposed a low-temperature pyrolysis treatment (LTPT) to destroy the caking properties of a fat coal (FC) and a 1/3 coking coal (CC). To reveal the factors affecting caking property, the changes in the chemical properties of pyrolysis products were analyzed using Fourier transform infrared spectrometry, X-ray diffractometer, and gas chromatograph/mass spectrometer (GC/MS). The in situ morphological changes in the liquid crystals produced by the two coal samples during LTPT process were also recorded using a hot-stage microscope. Of particular interest was a microscopic description of the factors affecting caking property. The results showed that the caking index (G) of FC decreased with increasing temperature and became zero at about 500 °C. Hot-stage microscope showed FC produced liquid crystals at 395 °C, the size of which continuously increased, with an accompanying of the generation of new liquid crystals. GC/MS showed large amounts of aliphatic hydrocarbons with the number of carbon of 6–25 (AlHsc6-25) and aromatic hydrocarbons with 2–4 rings (ArHsr2-4) were removed from FC. The aromaticity (fa) of FC increased only substantially from 395 to 494 °C. Meanwhile, the G of FC decreased only significantly in the same temperature range. A similar result was observed for CC. The removal of AlHsc6-25 leads to insufficient supply of hydrogen radicals; therefore, relatively high-molecular weight aromatics quickly cross-linked into semicoke. Additionally, the evolution of ArHsr2-4 and the increase in fa restrain the originating of crystal liquids. As a result, the loss of G was observed.

Enhanced pyrolysis of woody biomass under interaction of microwave and needle-shape metal and its production properties

Pyrolysis is one of the routes to value-added utilization of biomass, and the pyrolysis process can be enhanced with microwave heating, especially in the presence of catalyst. However, the catalysts used for biomass pyrolysis are usually in form of powder or grain, which leads to a problem that the catalysts are hard to separate from bio-char after the pyrolysis process. Based on this issue, the development of an enhanced microwave-assisted pyrolysis method without catalyst is of great significance. Therefore, this study proposes the method of microwave-enhanced pyrolysis of woody biomass via the interaction of microwave and needle-shape metal (iron-wire). In the paper, the pyrolysis characteristics and kinetic behaviors in the presence and in the absence of iron-wire were investigated, using pine sawdust and the mixture of biomass components as the material. Moreover, the properties of pyrolysis products with and without microwave-metal interaction were characterized, and the mechanism of microwave-metal interaction on the enhancement of pyrolysis was also analyzed. The results showed that the value of Ea reduced by 50% with microwave-metal interaction and the process under microwave-metal interaction was more conducive to the generation of bio-gas, with the yield of 62.43 wt%. Microwave-metal interaction increased ID/IG value of bio-char from 0.69 to 0.92, indicating an improvement of graphite degree, and decreased the content of aromatic compounds in bio-oil by 11.8%. The enhanced pyrolysis process is due to the increased electromagnetic distribution density after the insertion of iron wire into microwave and even microwave discharge occurred at the initial stage.

Effects of volatiles on properties of char during sequential pyrolysis of PET and cellulose

Interaction of the volatiles in co-pyrolysis of plastics and biomass is known to affect properties of pyrolysis products. Nevertheless, in co-pyrolysis, except the interaction between the volatiles, the volatiles could also interact with the char of same or different origin. Thus, understanding the specific effects of the volatiles of plastics/biomass on the evolution of the char from biomass/plastics is difficult. Hence, the investigation of the sequential pyrolysis of cellulose and polyethylene terephthalate (PET) at 600 °C was to explore the specific influences of volatiles from cellulose/PET in upper bed on the property of the char from PET/cellulose in lower bed. During sequential pyrolysis with cellulose in upper bed, the cellulose-derived oxygen-rich radicals promoted the cracking of the organic component on the PET-derived char, which significantly reduced the char yield while promoted the formation of heavy organics products and reduced hydrophobicity of the PET-derived char. Additionally, the cellulose-derived volatiles (e.g. ketones and aldehydes) involved in the secondary polymerization reactions with the volatiles from PET, forming more phenolics. PET-derived hydrocarbon-rich molecules did not promote charring reactions of the cellulose-derived char but increased hydrophobicity of the cellulose-char. Moreover, the varied interaction of the volatiles also significantly impacted thermal stability of the functional groups of char.

Simple descriptor based machine learning model development for synergy prediction of different metal loadings and solvent swellings on coal pyrolysis

The co-effect of solvent swelling and metal loading on coal pyrolysis was investigated through statistical analysis and machine learning. The distributions and properties of pyrolysis products, and the pyrolysis parameters were all considered. 22 targets were screened out by analysis of variance (ANOVA). Both linear and non-linear regression models aiming to predict these values were constructed, in which the swelling ratio and atomic descriptors collected from handbooks were taken as inputs. The symbolic transformation (ST) algorithm was involved to assemble a new feature and the model built on the advanced feature set displays higher prediction accuracy for all targets. The result of leave-one-out cross validation shows acceptable performance(R2 > 0.8) for most targets (19 of 22), and good performance (R2 > 0.9) for half of them (12 of 22). The importance of ST feature was verified, and the contribution of each single feature was clearly reflected in the formula of ST.

Comprehensive characterization of cattle manure bio-oil for scale-up assessment comparing non-equivalent reactor designs

Microscale pyrolysis reactors are used to predict the properties of pyrolysis products and/or optimize operating conditions. However, a major challenge encountered with these systems concerns reactor scale-up, since the conception of an equivalent large-scale configuration involves a complex step of mathematical analysis of the process. Furthermore, the effect of scale for different reactor configurations, considering the ways that the reactor design can influence pyrolysis, are still unknown parameters in the process. Therefore, this work evaluated the influence of scale, for different pyrolysis reactor configurations, on the composition of the liquid product (bio-oil) obtained by thermoconversion of cattle manure, using comprehensive chemical characterization by GC/MS and UHRMS, followed by statistical analysis. The gravimetric yields of the liquid fractions produced at the micro (R1) and semi-pilot (R2) scales showed a difference of ~10%, while similarity indices of ~90% were found for the volatile constituents of the bio-oils, determined by GC/MS. The ~10% disparity for the GC-analyzable bio-oil fraction was mainly associated with higher production of methoxyphenols in the R2 process. The molecular compositions determined by UHRMS showed degrees of dissimilarity < 18%, mainly reflected in higher formation of basic polar components of the O1 and O2 classes, and acids of the O4 class, in the R2 process. The results obtained in this work suggest that for a conventional pyrolysis process, the influence of scale for reactors of different configurations is less than 20%, with the products obtained showing similar compositions if the same operating conditions are used. Therefore, the challenges encountered in the scale-up phase of the system can be minimized, since changing the scale of the pyrolysis process, even using different reactors, will result in the formation of similar products.

Investigation on effect of coal fly ash on properties of corn straw pyrolysis products

The impact of coal fly ash (FA) is often ignored in the co-utilization of biomass and coal. Therefore, the influence of FA on the properties of pyrolysis products made from corn straw (CS) was investigated in this study. First, the distribution of co-pyrolysis bio-oil was investigated using pyrolysis-gas chromatography and mass spectrometry at 500°C-800 °C. Then, in a free-falling fixed-bed reactor, FA and CS were co-pyrolyzed, gaseous product yields were computed, and solid product composition and morphology were determined using X-ray diffraction, scanning electron microscopy, and the N2 adsorption–desorption isotherm, respectively. According to the findings, FA greatly promoted the degradation of oxygen-containing components in bio-oil and the formation of aromatic compounds at higher temperatures. The CS5-FA1 was the most favorable ratio for bio-oil production at 800 °C. Furthermore, the addition of FA had the highest stimulating effect on CO2 at 500 °C and 800 °C, and the yield of the other pyrolysis gases (CH4, CO, and H2) was also increased at 800 °C.

Residual moisture in the sewage sludge feed significantly affects the pyrolysis process: Simulation of continuous process in a batch reactor

Residual moisture (0–10 wt%) in the pyrolyzed fuel has a significant effect on the distribution and properties of pyrolysis products. It is due to the concentration of steam in the primary pyrolysis gas which is estimated to as much as 80 vol%. This is normally not taken into account in case of fixed-bed reactor studies at laboratory scale, where inert carrier gas is used to secure the absence of oxidizing agent, because the moisture is released within the beginning of heating and carried over from the hot zone before the pyrolysis starts. Consequently, the application of the results to large-scale technologies (working in the continuous sludge feeding regime) is not entirely valid because in industrial large-scale systems the steam passes through the hot pyrolysis zone and takes part in high-temperature reactions. In the experiments presented within this manuscript, we allowed the residual moisture typical for industrially dried sludge (10 wt%) to react within the pyrolysis process by incorporating it into the carrier gas (consisting finally of 70 vol% steam and 30 vol% He). This steam reacted within the pyrolysis process at temperatures 400–800 °C in a fixed-bed reactor. The results were thoroughly compared with the results of a previous study with pure helium atmosphere, within the same experimental setup. When comparing the experiments with and without steam in the carrier gas, a significant difference in the distribution and properties of the products was observed especially at temperatures above 600 °C. The use of steam as a carrier gas (instead of inert gas) resulted in a remarkably higher pyrolysis gas yield. The pyrolysis gas constituted of almost double the content of hydrogen with a decrease in the yield of the sludge-char. Moreover, particular changes in sludge-char properties were observed. Not only the steam enhanced textural properties of the sludge-chars, especially the specific surface area and the total specific pore volume, but it also resulted in a significantly lower content of C, H, N and S and lower heating value of the sludge-char. These parameters can be decisive in case of sludge-char utilization ranging from agronomic through adsorbents to fuel use. Our approach provides a simplified way to better predict the distribution and properties of pyrolysis products in large-scale units. This can be time and money saving and is crucial to make decisions about the applicability of pyrolysis technology to specific sewage sludge products.

Slow Pyrolysis of Flax Production Waste

The slow pyrolysis of flax shive and the cellulose residue of flax shive obtained by ethanolysis was studied in this work. Investigation of temperature effect on physical properties of pyrolysis products in the range of 500-750 o? on a laboratory slow pyrolysis unit was presented in this manuscript. The experimental obtained data of initial properties of investigation samples, thermal stability of samples, heat effects of pyrolysis process, chemical composition and physical properties of liquid and gaseous pyrolysis products are presented.

Fast Pyrolysis of Flax Shive in a Screw‐Type Reactor

AbstractA novel screw‐type reactor for the fast pyrolysis of agricultural waste (flax shive) is described. A preliminary study on the influence of process parameters on the yield, composition, and properties of pyrolysis products was carried out. Based on the results obtained, the optimal conditions of fast pyrolysis of flax shive particles in terms of feedstock particle size, solid residence time, and process temperature were identified. Considering the construction, the developed reactor seems to be close to the screw fluidized bed and auger reactor and is characterized by a simple design and operation control. Moreover, the proposed reactor can be used for continuous pyrolysis without any significant modification.

Template-assisted synthesis of high-efficiency bifunctional catalysts with roller-comb-like nanostructure for rechargeable zinc-air batteries

One-dimensional (1D) nanomaterials which are rich in multiple transition metal-nitrogen-carbon active sites have great potential as catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, a roller-comb-like 1D nanostructure is synthesized by a template-assisted method with pyrolysis to create such bifunctional catalysts. Initially, two zeolite imidazole frameworks (ZIF-8 and ZIF-67) are simultaneously grown on polypyrrole (PPy) nanotubes, which are then calcined into 1D N doped carbon nanotubes (NCNTs) modified with Zn, Co nanoparticles and micro-CNTs. The simultaneous formation of two ZIFs on the PPy tubes reduces their particle sizes, which subsequently increases the density of metal nanoparticles on the 1D CNTs. Importantly, the co-deposition of both Zn and Co nanoparticles is a necessary condition to generate a large amount of micro-CNTs, which are embedded with metal nanoparticles at their ends, promoting the connectivity between the metal active sites. The temperature effect on the morphology, composition and properties of pyrolysis products was investigated in detail, which identified that the catalyst synthesised at 800 °C exhibited the best bifunctional ORR/OER performance with a ΔE value as low as 0.73 V. A rechargeable Zn-air battery assembled with this catalyst achieves an excellent peak power density of 194.3 mW cm−2.