Tar Content Research Articles

Gasification of different biomasses in a concurrent fixed bed reactor: thermodynamics assessment towards its bioenergy potential

Gasification is considered a promising technique for converting biomass into fuels and chemicals products. Its viability must be guaranteed when obtaining great conversion yields, gas with high calorific value and low tar content. It is also important to develop efficient equipment that work with different biomasses. Aiming to assess this potential, this paper evaluated the operational performance of a fixed-bed and concurrent flow gasifier as well as the gas quality by using five different biomasses in gasification process, which were: in natura and torrefied eucalyptus woodchips, in natura and torrefied pine pellets and eucalyptus charcoal. Gas and biomasses characterizations were made and some improvements for conversion optimization were discussed. The results showed that biomasses gasification was technically feasible, reactors’ performance and operation were affected by biomasses chemical and physical properties. Torrefied biomasses reduced the percentages of CO2 (-18.4%) and H2 (-12.1%), while increased the CO (+12.7%) in the gas, contributing positively to the rise in calorific value. The highest efficiencies were obtained in eucalyptus woodchips gasification, on average 53.2% of cold efficiency, with no differences between in natura and torrefied woodchips. Finally, in order to increase biomass conversion into gas, modifications in the reactor reduction zone are recommended, such as the creation of a physical barrier to increase gases residence time. Our study will help encourage bioenergy and gasification technologies in developing countries.

Enhanced Biomass Combustion via Bluff Body- and Impingement-Stabilized Natural Gas-Air Premixed Flames

ABSTRACT The preheating, flow recirculation and impingement effects of trapezoidal bluff bodies increased the biomass heating value-based combustion efficiency to 94% at a firing intensity of 78 MW/m3. A sawdust-laden air stream was combined to bluff body-stabilized natural gas-air premixed flames in three different configurations. A common impingement of opposing fuel-lean mixture jets with a sawdust-laden air cross-flow upstream of a solid bluff body provided a peak turbulent kinetic energy of 11.8 m2/s2. Using opposing jets with ports of multiple sharp corners minimized the flame length/combustor diameter ratio to 4.2. The combination of premixed flame impingement on the combustor base with the flow stagnation effect inside hollow bluff bodies provided a maximum blow-off velocity of 19.5 m/s at Ф = 0.8. Delaying the biomass interaction with the premixed flames decreased the peak exhaust NOx concentration to 0.17 g/kW.hr. Confronting the premixed flame jets by the sawdust-air laden jet provided a superior flow configuration in which the premixed flame high temperatures provided effective tar cracking, thus minimizing the exhaust total tar content to 50 mg/Nm3. A simultaneous peak exhaust soot volume fraction of 7 × 10−8 and a peak exhaust CH4 concentration of 0.1% were thus combined to a peak CO concentration of 14 mg/MJ.

Holistic characterization analysis of tar waste content from gasification process at Surakarta landfill

Surakarta is facing serious problems related to waste management at the Putri Cempo landfill. PT. Solo Citra Metro Plasma Power with the Surakarta city government built a waste power plant installation with gasification technology. Tar waste is a gasification liquid product that is dangerous if not managed. This study aimed to determine the heavy metal content and toxicity level of gasified tar waste using the atomic absorption spectrometry (AAS) and lethal dose-50 (LD<sub>50</sub>) acute toxicity test. The parameters of heavy metals tested are lead (Pb), copper (Cu), iron (Fe), zinc (Zn), and total chromium (Cr). In the LD<sub>50</sub> test, the animals were divided into 5 groups, namely 1 control group and 4 groups with doses of 0.50 mL, 1 mL, 2 mL, and 4 mL. The results showed that the tar contained 17.4 mg/L of iron, 3.5 mg/L of zinc, and <0.01 mg/L of lead, copper, and chromium. Acute toxicity tests did not cause death in the animals but still showed toxic symptoms, so the LD<sub>50</sub> value is declared pseudo. The content of some heavy metals in tar is within safe limits and the level of toxicity is relatively harmless.

Chemical looping gasification of waste plastics for syngas production using NiO/Al2O3 as dual functional material

This study investigates the chemical looping gasification (CLG) of typical waste plastic, polypropylene (PP), using NiO/Al2O3 as a dual functional material, i.e. oxygen carrier (OC) and catalyst. The whole PP-CLG process comprises PP gasification, coke steam oxidation, and OC air regeneration with the first one being the key step for syngas production. Four operation modes for PP gasification were studied and compared, which were distinguished by whether PP and OC were premixed, and whether the heating rate was fast or slow. Significant differences in the product distribution, PP conversion ratio, and the roles that NiO/Al2O3 played were observed under different modes. The highest syngas yield (64.7 mmol/g-PP), carbon conversion (64.9 %), and minimum coke deposition (19.3 %) during PP gasification were achieved through a combination of premixing and fast heating (Type A). Benefitting from its extensive lattice oxygen supply and the effective catalytic cracking capabilities of NiO/Al2O3, Type A accelerated volatile conversion, demonstrated elevated CO selectivity, and reduced tar content, thereby enhancing PP-syngas conversion efficiency. Direct CLG of PP was genuinely realized in Type A, which is different from the traditional pyrolysis-reforming scheme for syngas production. Characterizations further illustrated that the NiO/Al2O3 in Type A produced coke that was the easiest to remove, experienced less sintering, and exhibited the highest lattice oxygen utilization ratio. The findings are expected to provide practical guidance for the choice of a suitable reaction pathway maximizing the waste plastics to syngas conversion.

Torrefaction integrated with steam gasification of agricultural biomass wastes for enhancing tar reduction and hydrogen-rich syngas production

Steam gasification is considered as a promising technology for conversion of various biomass wastes to valuable hydrogen (H2)-rich gas products that can be applied for the sustainable production of green hydrogen and methanol. However, some inevitable problems such as high tar content and low cold gas efficiency greatly hinder its broad application. Torrefaction has been widely employed for upgrading low-rank biomass sources that favors the follow-up gasification process, resulting in low tar yield and high syngas yield. Torrefied biomass usually shows higher energy density, improved grindability characteristics, and lower O/C and H/C ratios. This research work studies the effect of torrefaction on steam gasification of corncob (CC) and rice husk (RH). The mechanisms of biomass torrefaction integrated with steam gasification are also given. Biomass torrefied at a relatively high temperature (280 °C) is more efficient to extract the oxygenated volatiles, reducing the generation of tar and particulate matters during the gasification process. The increase of torrefaction temperature resulted in an increase of H2 yield and a decrease of CO yield, corresponding to an increase of H2/CO ratio. Particularly, the H2 yield in the CC-derived syngas increased from 6.38 mmol/g (raw) to 12.01 mmol/g (280 °C), and the H2 yield in the RH-derived syngas increased from 4.33 mmol/g (raw) to 12.97 mmol/g (280 °C). Steam gasification of RH torrefied at 280 °C achieved a maximum H2/CO ratio of 2.84. After torrefaction of CC and BB at 280 °C, the tar yield of steam gasification was below 1% [gasification temperature: 800 °C, mass ratio of steam to biomass (S/B): 1]. In general, the torrefaction pretreatment of biomass at relatively high temperatures (i.e., 280 °C) favors the steam gasification process under an appropriate S/B (i.e., 1) in terms of improving the syngas quality and reducing the tar production.

Gasification of olive tree pruning in a rotary kiln reactor integrated with radio frequency plasma torch

Olive tree pruning pellets are gasified by air in a bench-scale rotary kiln gasifier integrated with a radio frequency plasm torch. For the first time the technical suitability of the proposed configuration is herewith assessed. The effect of biomass flowrate (190–900 g/h), equivalence ratio (0.15–0.30), gasification temperature (650–900 °C), on syngas composition and yield is investigated. By increasing the biomass flowrate, from 190 to 900 g/h at 800 °C, both hydrogen and carbon monoxide mole fractions decreases, while the carbon dioxide mole fraction increase, with a drop in CGE from 76 % to 26 % increasing the biomass flowrate from 190 to 900 g/h at 800 °C. Higher temperature has a beneficial effect on syngas composition and CGE that increase from 20 % to about 64 % by increasing the temperature from 650 to 900 °C at a biomass flowrate of 450 g/h. The tar content shows a decreasing trend with equivalence ratio and temperature while it shows an increasing trend with biomass flowrate. The integration of the radio frequency plasma torch treatment of raw gas produced at 650 °C, with equivalence ratio of 0.15 and a biomass flowrate of 450 g/h shows good performance in hydrocarbons conversion, with a significant increase in terms of hydrogen yield. The H2/CO molar ratio increased by 104 % due to reforming reactions generating H2 and CO. A reduction of CO2 is also observed. With the RFPT treatment, gravimetric tar content was lower than the limit of detection while the concentration of light aromatics, i.e. benzene and toluene, decreases from 8.3 g/Nm3 to 2.2 g/ Nm3. The proposed post-gasification technology is worthy of further investigation for hydrogen production from biomass.

Deeper insights into the devolatilization mechanism of biomass fixed-bed gasification under various atmospheres

In recent years, biomass oxy-fuel gasification has prompted increased interest for its ability to produce a gas with low tar content and to assist in carbon reduction. It is noteworthy that the type of atmosphere is a crucial factor influencing the devolatilization process in biomass gasification and the specific mechanisms by which an oxy-fuel atmosphere influences the devolatilization process remain inadequately explored. This work aimed to investigate the effect of various reaction atmospheres on devolatilization behavior, reaction kinetics, intermediate product formation, and biochar functional groups (BFGs) evolution. In comparison to an inert atmosphere, the oxy-fuel atmosphere facilitated the release of volatiles, and enhanced energy self-sustainability within the devolatilization system. The presence of O2 and CO2 promoted the generation of potential anhydrosugars while suppressing the formation of phenolic compounds. The synergistic effect present in the oxy-fuel atmosphere augments the exothermic effect and promotes the release of volatile and alkane gases during the devolatilization process. Furthermore, as oxygen concentrations increased in the reaction atmosphere, the sequential response of BFGs primarily followed the order: C-O → aromatic ring → C-OH/C–H/COO– → C=O. Moreover, advanced characterization analyses revealed that the oxy-fuel environment was more effective in promoting the aromatization and pore structure of biochar than an inert atmosphere. Collectively, these findings have substantial implications for reaction modeling in biomass fixed-bed gasification under real gas atmospheres and guide future research on tar control strategies.

Gasification of sago dreg waste in a top-lit updraft fixed bed gasifier: Syngas composition and its effect with additional Al2O3 as catalyst

Sago-based foods have become a staple food in eastern Indonesia. Sago waste, as a by-product, has the potential to be used as a renewable energy fuel. This research aims to use sago dregs waste as an energy source by converting it into renewable energy using Top Lit Updraft (TULD) fixed bed gasification. Al2O3, a potential solid waste derived from coal fly ash, is also being investigated for use in sago dreg pellets.The two various Al2O3 contents in sago dreg pellets that will be examined with 5 % Al2O3 and 10 % Al2O3. Operational parameters employed in the gasification process involving the TULD reactor, such as gasification temperature, air flow rate, air-to-fuel ratio (AFR), and syngas assessment. According to the results, adding Al2O3 as a catalyst to sago dreg pellets can improve syngas production (H2, CO, and CH4). The most significant alteration is that the average hydrogen gas (H2) content has increased, with the greatest being in 5 % Al2O3 with 31.65 %, and 10 % Al2O3 with 29.94 %. Meanwhile, the CO and CH4 gas content was found to be highest at 10 % Al2O3, with each experiencing an increase in average (CO 4.33 % and CH4 26.45 %) as compared to sago dregs pellets without Al2O3. Finally, sago dregs pellets with an Al2O3 catalyst have a high potential as an alternative energy fuel for internal combustion engines with H2/CO of 1.65 and 1.51 respectively, for 5 % Al2O3 and 10 % Al2O3, with low tar content.

Biorefinery-oriented pyrolysis and anaerobic fermentation synergies: Leveraging biomass tar for enhanced chemical production from food waste

The carboxylic platform via mixed culture anaerobic fermentation holds significant potential for biorefinery applications. However, effective and economical methanogenesis inhibition remains crucial for maximizing production efficiency. This study investigates the use of biomass tar, derived from the pyrolysis of rice husk, as a methanogenesis inhibitor to enhance the anaerobic fermentation of food waste and boost the production of reduced fatty acids. The experimental results demonstrated that adding 5.0 g/L of tar achieved the highest hydrogen production, reaching 65.0 mL/g VS. Furthermore, increasing tar concentrations led to higher yields of reduced and longer-chain fatty acids, with butyrate production peaking at 726.8 mg COD (chemical oxygen demand)/g VS (volatile solid) with 30.0 g/L tar, and caproate at 128.6 mg COD/g VS with 10.0 g/L tar. GC-MS analysis identified phenolic compounds and furan derivatives as the primary inhibitory agents, which gradually degraded during fermentation. Microbial community analysis revealed that the tar-based inhibitors effectively suppressed dominant methanogenic archaea, including Methanothrix, Methanobacterium, and Methanosarcina, while promoting the enrichment of chain-elongating bacteria such as Clostridium_sensu_stricto and Clostridium_IV. This study suggests that integrating biomass tar from pyrolysis with anaerobic fermentation can serve as a highly efficient biorefinery approach, fully utilizing diverse organic wastes for sustainable energy production.

Method of calculation of a two-stage separation system of a biofuel production installation

Currently, the processing of plant waste is a promising area of development in modern energy. There are many methods for recycling waste, but not all of them are economically feasible and environmentally friendly. One of the most common processing methods is fast ablative pyrolysis, designed for thermal processing of waste without access to oxygen. As a result of such processing, carbon residue and pyrolysis gas are formed. The amount of pyrolysis gases produced is 60 % or more of the mass of processed raw materials. In order for pyrolysis gases to become high-quality fuel, they must be subjected to a separation process that takes place in devices called a vapor condenser. When separating pyrolysis gases, it is better not to use conventional oil and gas condensers since the condensed pyrolysis gases have a high tar content, which causes faster wear of the device. For the installation for the production of pyrolysis fuel, a two-stage separation system is proposed, designed to separate pyrolysis gases into fractional components: pyrolysis distillate, non-condensable combustible gas and water. The article presents the design of a two-stage separation system. The principle of operation of a two-stage separation system is described, and a diagram of its structure is given. A method for calculating a two-stage separation system is presented, which makes it possible to determine the geometric parameters of scrubber and ejector type capacitors.

An entrained flow biomass gasification technology with the fluidized bed concept for low-carbon fuel production

For accomplishing the vision of building of a net-emission zero society, low-carbon fuels such as e-fuel, Sustainable Aviation Fuel (SAF), and chemical products generation, plays a significant role. Especially, among the low carbon fuels, SAF is the most crucial. Ammonia and electric aircraft are under way as alternatives to fossil-derived jet fuel (kerosene). However, none of these have yet found their way to commercialization. Among the SAF production technology, biomass gasification and Fischer-Tropsch (FT) synthesis technology are one of the lowest CO2 emission processes, according to Life Cycle Assessment (LCA) analysis. However, at present there are some issues about biomass grinding, tar, ash treatment, gas purification and wastewater. We, at Mitsubishi Heavy Industries (MHI) R&D laboratory have developed entrained bed gasification, adopting the fluidized bed concept in which biomass particles are recirculated in the gasifier without fluidizer. Principally desired outcomes of this development was to reduce the grinding power, simplify the structure by using atmospheric pressure process, and lower tar concentration while maintain suitable temperature to prevent ash from melting inside gasifier. Empirical and actual results showed that the developed gasifier can obtain high carbon conversion ratio and low tar as compared to the traditional gasification processes for low-carbon fuel production and produce reliably stable syngas for low-carbon fuel synthesis with single gasifier. Based on the pilot plant operation results, effectiveness of moderate (1223 – 1323 K) temperature gasification with this concept has been demonstrated too. As a conclusion, development needs and expectation of gasification technology for contributing to carbon neutral society are mentioned.

Behaviors and mechanism of volatiles producing during coal pyrolysis with calcium oxide loading: Insights from model compounds analysis

Calcium is a highly effective catalyst for controlling the tar compounds produced during the pyrolysis of low-rank coal, forming valuable end products. However, the exact catalytic mechanism of calcium in coal pyrolysis remains unclear due to the complex nature of coal. In this study, the pyrolysis process and tar composition of lignite, both with and without the addition of calcium, were investigated across three distinct temperature intervals. The addition of calcium oxide increased the hydrocarbon content of tar by 16.39 % in the low-temperature range and 26.53 % in the intermediate-temperature range. Four model compounds containing different coal-related functional groups were selected to investigate the effects of calcium on pyrolysis performance and tar composition using thermogravimetric analysis, fixed bed reactor experiments, gas chromatography/mass spectrometry, in situ Fourier transform infrared spectroscopy, X-ray diffractometer, and X-ray photoelectron spectroscopy. The addition of calcium did not affect the thermal decomposition of polystyrene or polyethylene terephthalate; however, the primary pyrolysates underwent secondary reactions on the surface of calcium, which affected the composition of the liquid pyrolysis product. Meanwhile, calcium interacted with the carboxyl and phenolic hydroxyl groups in trimeric acid and phenolic resin to form carboxylates and phenates, which affected the thermal reaction and distribution of liquid products. The influence of calcium on the transformation mechanism of coal-related functional groups provides a theoretical basis for understanding the mechanism of calcium-catalyzed coal pyrolysis.

Imidazole ionic liquid effects on coal swelling behavior and pyrolysis characteristics: Experiment and molecular simulation

In view of low-rank coal conventional swelling solvent large pollution and the clean efficient utilization of coal, the effects of imidazole ionic liquid (IL) pretreatment with different anion groups as green solvent on coal thermal expansion and pyrolysis performance were investigated. IL interacts with coal molecules, destroying the hydrogen bonds, resulting coal expansion. Different anion groups have different modification effects, [Bmim]Cl has the best swelling effect, which is 17.37 % higher than raw coal, and the best modification time is 24 h. In addition, IL modification has a catalytic effect on coal pyrolysis, which can significantly reduce the maximum weight loss temperature and increase tar content. Coal solvent pretreatment provides a good theoretical basis for application of swelling and pyrolysis. The reduction of thermochemical reaction temperature not only reduces the content of heavy groups in pyrolysis products, but also provides new ideas for carbon emission reduction.

A pilot study on a 30 t/h biomass gasification-combustion plant

As a renewable energy with zero carbon emission, the utilization of biomass has attracted widely studied. One of the most effective methods is to gasify the biomass into high-quality gas fuel. In the recent years, the majority of research on biomass gasification is conducted in the laboratory. However, it lacks the research in engineering application scale. In this work, a biomass gasification-combustion plant was designed and built to provide the industrial steam with a rate of 30 t/h for a food industrial park. The agricultural and forestry waste biomass was gasified in a gasifier, and then the product gas combusted in a boiler to supply the steam. The characteristics of the product gas from the gasifier were studied. The corrosion and pollutants in the combustion process were investigated. In the gasification process, the main components of the product gas are CO, H2 and CH4. CO and H2 account for 29.55 vol%-30.56 vol% and 11.65 vol%-15.35 vol%, respectively. The calorific value of the product gas is 5.88–6.29 MJ/m3. The tar concentration is 110.58–155.07 g/Nm3. At the outlet of the boiler, the concentration of the filterable particulate matter is 300.25 mg/Nm3, and the particle size is concentrated at 1.00–2.50 μm. The concentration of the condensable particulate matter (CPM) is 157.14 mg/Nm3, and the proportion of water-soluble ions in CPM is 86.36 wt%. The concentration of Cl−, SO42-, NH4+ and Na+ in CPM is relatively high, with the values of 28.83 mg/Nm3, 10.29 mg/Nm3, 7.46 mg/Nm3, and 5.06 mg/Nm3, respectively. During the half-year running, the ash deposition and corrosion were detected in the boiler heating surface and the economizer. The ash deposit in the boiler is mainly composed of the sulfate and silicate, such as CaSO4, Zn2SO4, Na2SO4 and K3Na(SO4)2. The ash deposit in the economizer is primarily composed of the sulfate and a small amount of alkali metal chloride. The flue gas reaches the emission requirement after passing through the pollution control devices and can be discharged into the atmosphere.

MICROWAVE THERMOLYSIS OF HEAVY OIL IN THE PRESENCE OF AN IRON-BASED CATALYST

Global demand for energy is growing every year, and there is also a decrease in reserves of traditional hydrocarbons. Today, the share of highly viscous and bitumen oil reserves is 25 % of the world. Production of extra-viscous oils will grow around the world.In order to solve the problem of developing highly viscous and bitumen deposits and increase oil recovery, we offer a technology for using aquatermolysis catalyst. Experience in the use of in-situ chemical conversion of organic matter has shown sufficient effectiveness in solving this problem.In this work, laboratory studies were carried out to improve the rheological characteristics of highly viscous and bituminous oils using microwave exposure using an iron-based catalyst precursor.The addition of a catalyst precursor containing iron nanoparticles provides more uniform and higher-speed heating when the formation is exposed to high-frequency electromagnetic radiation. This heating technology has been used in various fields to achieve environmental safety and high energy savings, in comparison with traditional methods that cannot achieve these indicators. The proposed technology simplifies the development process by eliminating the injection of coolants, thereby providing prospects for the processes of intensification of production and its subsequent transportation.In order to assess the possibility of effective application of high-frequency electromagnetic radiation to the formation in a particular field, first of all, data on the rheological characteristics of oil after exposure should be presented.These laboratory studies showed a decrease in viscosity under microwave exposure in the presence of a catalyst up to 1.8 times compared to the original oil sample. A decrease in viscosity characteristics was recorded already from a five-minute microwave exposure, as well as a change in the component composition of the oil, the tar content decreases by 27 % relative to the initial oil sample. This combination of the two methods of action provides new opportunities for the development of new technologies, as well as more efficient production of heavy oil.

Three-dimensional computational fluid-dynamic simulation of polypropylene steam gasification

Among the recycling techniques, gasification allows to obtain a hydrogen-rich gas from polypropylene (PP), a widely used thermoplastic material. In this work, devolatilization and steam gasification tests of PP were conducted in fluidized bed reactors. The results show a gas yield of 1.3 and 3.0 Nm3/kgPP, and a tar content of 117.3 and 20.9 g/Nm3 from devolatilization and gasification, respectively. Experimental results provide an overall overview of this process, able to produce a syngas with an H2-content of 50 vol%dry.Experimental data coupled with kinetic analysis were used to develop a computational fluid dynamic model (CFD) capable of describing both thermal degradation and subsequent gasification reactions. Although some discrepancies on water conversion and H2/CO ratio probably related to the influence of steam in radical chain-scission the model allows to describe gas production and hydrocarbons evolution providing important support for modeling and sizing of fluidized bed reactors on an industrial scale.

Parameter study of waste shiitake substrate/waste polyethylene Co-gasification using Aspen Plus kinetic modeling

Waste Shiitake Substrate, a major agricultural waste in Taiwan, is typically packaged in plastic bags (Waste Polyethylene, PE) during mushroom cultivation process. Consequently, these plastic bags become additional waste that requires proper disposal. In recent years, Taiwan has produced over 150,000 tons of waste shiitake substrate annually, with approximately 1580 tons of plastic bags used for mushroom cultivation. Up to now, there has not been an effective method for handling this waste. This study aims to develop a co-gasification process using the complementary characteristics of WSS and PE. Unlike traditional direct combustion, the co-gasification approach can convert these wastes into cleaner bioenergy. This study aims to develop an Aspen Plus model for a laboratory-scale 1 kWth bubbling fluidized bed gasifier. This model incorporates kinetic reactions and tar formation during co-gasification. The model accurately predicted the experimental results. Different variables were investigated, including gasifier temperature, blending ratio (BR) of the two fuels, mixing ratio (MR) of the gasifying agent, and equivalence ratio (ER). The results showed that hydrogen production correlated positively with the steam-to-carbon ratio in the gasification medium, whereas carbon monoxide (CO) was more affected by the feedstock type and equivalence ratio, with CO reaching its peak at an equivalence ratio of 0.2. When gasifying using only waste shiitake substrate (BR = 0%), at an ER of 0.2, a gasification furnace temperature of 950 °C, and an MR of 100% (pure CO2), the maximum CO mass flow rate in the syngas is obtained. Waste plastics contain significant amounts of volatile matter and no oxygen, leading to increased production of CH4, CO, and H2 during co-gasification with the addition of waste plastic. For plastics, high temperature and low ER conditions promote the production of CO, H2, and CH4 because of the significant tar content, thereby enhancing the Cold gas efficiency (CGE). When the gasification temperature is 950 °C, with 80% polyethylene (BR = 80%) and an ER of 0.1, the highest HHV is achieved. These results can serve as a reference for determining the operational conditions for the scale-up of gasification systems.

Determination of Coal Tar Concentration in Therapeutic Shampoo by Fluorescence Measurements of Perylene

Determination of Coal Tar Concentration in Therapeutic Shampoo by Fluorescence Measurements of Perylene

Experimental analysis of the effects of feedstock composition on the plastic and biomass Co-gasification process

Co-gasification is a feasible approach to manage fast-growing plastic and biomass waste issues. The current work examines air gasification of plastic waste blending with biomass. The influence of plastic-type and biomass characteristics on product distribution under the same operating condition was studied. Ethylene-vinyl acetate, high-density polyethylene, and polypropylene were the investigated plastics while the biomass materials considered were pine sawdust (PS), used ground coffee (UGC), and wheat straw (WS) are compared. Additionally, co-gasification and thermogravimetric analyses (TGA) of plastic and individual biomass components, namely, cellulose, hemicellulose, and lignin, were conducted to identify the nature of the synergy arising from plastic and biomass integration. Similarities in the chemical structure and composition of the investigated plastics resulted in the type of plastic marginally influencing product distribution. The gas composition included 4.6 vol% CH4, 37.5 % CO2, 5.3 % CnHm, 42 % CO, and 10.8 % H2, with yields of 5.9 wt% char, 39.5 wt% gas, and 54.8 wt% tar. Conversely, the type of biomass had a substantial effect on both gas composition and product yields. WS and UGC, characterized by higher hemicellulose and lignin content, generated more hydrogen with 14.4 and 13.3 vol%, respectively, and exhibited lower tar content (45.7 and 47.8 wt%) compared to PS, which has a higher cellulose content and yielded 54.8 wt% tar. During EVA/cellulose co-gasification, the predominant gases produced are CO and CO2, with H2 concentration of 7.2 vol%. In contrast, co-gasification of EVA/xylan and EVA/lignin yields 13.5 and 19.9 vol% hydrogen, respectively. Interactions and synergism between the plastic and biomass were found to be more intensified when the biomass contained greater proportions of cellulose and lignin. Co-gasification and TGA analyses indicated that plastic/cellulose and plastic/lignin interactions in the gas and solid phases (volatile-volatile and volatile-char interactions) and plastic/xylan interactions in the gas phase (volatile-volatile interactions) were significant. Modeling the predictability of the output data revealed that if interactions between the plastic and biomass components are accounted for, the co-gasification results are predictable with a credible accuracy for all biomass types. The predictability model offers a practical approach for selecting an appropriate co-gasification feedstock combination to give a targeted process performance.

Physicochemical characterization, chemical composition and antioxidant activities of pyroligneous acids from cocktails of wood and agricultural residues from Ivory Coast

Physical, chemical characterization and antioxidant activities were assessed on six pyroligneous acids from four wood cocktails (WCV1, WCV2, WCV3, WCV4) and two types of agricultural residues (PA1, PA2) from Ivory Coast. Physical and chemical parameters of pyroligneous extracts were determined using a density meter, refractometer, pH meter, colorimetric titration, drying and sensory test. WCV2 alone simultaneously met all the standards set by the Japanese Pyroligneous Liquor Association, with a distinct smoky odour, a clear light-brown color, a pH of around 3, a density in the 1.010–1.020 g/mL range, and an ignition residue content of less than 0.2 %. In addition, WCV3, blackish in colour, had the highest Brix value (9) with a lower moisture content than the others (89.92 %), thus reflecting a high soluble tar content. Furthermore, all pyroligneous liquids had a high moisture content (89.92–99.08 %) and a low total acid content (0.90–2.10 %) compared with the literature. However, the results of GC-MS analysis revealed the presence of major compounds such as acetic acid, propionic acid, phenol, guaiacol and 3-methylphenol in the organic phase of pyroligneous extracts. FTIR analysis identified alkaloids, phenolic compounds and flavonoids in the aqueous phase of pyroligneous extracts. The presence of these compounds was confirmed by a phytochemical screening test. Finally, antioxidant activities with DPPH and ABTS methods showed that WCV2 had the best antioxidant properties due to its high guaiacol and syringol content. On the other hand, WCV3 showed a good antioxidant efficacy only by the DPPH method, probably due to its high flavonoid content.