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Torrefaction experiments were carried out on some Nigerian woody ( Albizia pedicellaris (AP), Tectona grandis (TK), Terminalia ivorensis (TI)) and non-woody ( Sorghum bicolour glume (SBG) and stalk (SBS)) biomass resources. The influence of process conditions and consequent change in the elemental configuration of the biomass samples were observed. Biomass type played a dominant role in the solid yield recording 71% for woody and 58% for non-woody samples at 270 °C, while temperature showed the greatest influence with solid yield dropping from an average of 80% (at 240 °C) to 50% (at 300 °C). Both volatile matter and fixed carbon contents experienced significant changes after torrefaction and a decline in O/C ratio from 0.6 to 0.3 was noted. Among the woody biomass, TI experienced the highest increase in higher heating value (HHV) of approximately 38% as compared to AP (32%) and TK (32%), and was subsequently selected for decomposition kinetic study. The decomposition kinetics showed that activation energy ( E ( α )) for the hemicellulose degradation stage ranged between 137 and 197 kJ mol −1 for conversion ( α ) between 0.1 and 0.24 implying that biomass kinetics within this decomposition region is a multi-step reaction. The GC/MS analytical technique revealed that the presence of levoglucosan was highest (7.1%) in woody biomass, while phenolic compounds made up more than one-third of the group of compounds identified. [ABSTRACT FROM AUTHOR]

A non-isothermal decomposition of Moringa oleifera husk and Delonix regia seed pod was carried out in an N2 pyrolytic condition with the primary objective of undertaking the kinetics modeling, thermodynamics and thermal performance analyses of the identified samples. Three different isoconversional models, namely, differential Friedman, Flynn–Wall–Ozawa, and Starink techniques were utilized for the deduction of the kinetics data. The thermodynamic parameters were deduced from the kinetic data based on a first-order chemical reaction model. In the kinetics study, a strong correlation (R2 > 0.9) was observed throughout the conversion range for all the kinetic models. The activation energy profiles showed two distinctive regions. In the first region, the average activation energy values were relatively higher—a typical example is in the Flynn–Wall–Ozawa technique—MH (199 kJ/mol) and RP (194 kJ/mol), while in the second region, MH (292 kJ/mol) and RP (234 kJ/mol). It was also demonstrated that the thermal process for the samples experienced endothermic reactions thought the conversion range. In summary, both the kinetic and thermodynamic parameters vary significantly with conversion—underscoring the complexity associated with the thermal conversion of lignocellulosic biomass samples. [ABSTRACT FROM AUTHOR]

• Successful extrusion of torrefied paper-plastic waste blends. • Extrusion of torrefied waste blend reduced variability by a factor of 7. • The plastic layer formed around the extruded fiber prevents water absorption. • The extent of torrefaction influences the combustion properties. With the continued growing U.S. population, solid waste generation will increase, which will lead to undesired and significant growth in landfilling. Thermal treatment can turn these high calorific value wastes into fuels that can be used in small-to-large power plants. This article focuses on using blends with 40% plastic and 60% fiber wastes and converting them into densified solid fuel by torrefaction and extrusion. The material was torrefied at 300 °C to obtain torrefied samples with different mass losses, ranging from 0% to a maximum of 51%. The torrefaction results showed a clear synergy between plastics and fibers. The torrefied material was then extruded into 9 mm diameter rods and the products were characterized by molecular functional group analysis, thermomechanical analysis, dynamic mechanical analysis, dynamic rheological measurement, density measurement, flexural testing, water absorption test, size distribution measurement, heat content test, and combustion test. The fiber content in the material decreased as mass loss increased, and the process reduced significantly the variability of the material. The heat content increased as the mass loss increased. The plastic in the feedstock acted as a process enabler as it imparted properties like bindability, water resistance, high heat content, and increased degradation reaction rate. [ABSTRACT FROM AUTHOR]

Efficient conversion of all components in lignocellulosic biomass is essential to realizing economic feasibility of biorefineries. However, lignin cannot be fermented using biochemical routes. Furthermore, high lignin and high ash residues from simultaneous saccharification and fermentation (SSF) is difficult to thermochemically process due to feed line plugging and bed agglomeration. In this study a corn stover SSF digester residue was thermally pretreated at 300 °C for 22.5 min and gasified in a fluidized bed gasifier to study the effect of thermal pretreatment on its processing behavior. Untreated, pelletized SSF residue was gasified at the same conditions to establish the baseline processing behavior. Results indicate the thermal pretreatment process removes a substantial portion of the polar and non-polar extractives, with a resultant increase in the concentration of lignin, cellulose, and ash. Feed line plugging was not observed, although bed agglomeration occurred at similar rates for both feedstocks, suggesting that overall ash content is the most important factor affecting bed agglomeration. Benzene, phenol, and polyaromatic hydrocarbons in the tar were present at higher concentrations in the treated material, with higher tar loading in the product gas. Total product gas generation is lower for the treated material, although overall gas composition does not change. [ABSTRACT FROM AUTHOR]

Mixed cultures fermentation can be used to convert organic wastes into various chemicals and fuels. This study examined the fermentation performance of four batch reactors fed with different agricultural (orange, banana, and potato (mechanical and steam)) peel wastes using mixed cultures, and monitored the interval variation of reactor microbial communities with 16S rRNA genes using Illumina sequencing. All four reactors produced similar chemical profile with lactic acid (LA) as dominant compound. Acetic acid and ethanol were also observed with small fractions. The Illumina sequencing results revealed the diversity of microbial community decreased during fermentation and a community of largely lactic acid producing bacteria dominated by species of Lactobacillus developed. [ABSTRACT FROM AUTHOR]

The reduction of cobalt (Co) catalyst supported on silica nanosprings for Fischer-Tropsch synthesis (FTS) has been monitored by X-ray photoelectron spectroscopy (XPS) and compared to FT catalytic activity. The cobalt is present in the starting catalyst as a Co 3 O 4 spinel phase. A two-step reduction of Co 3 O 4 to CoO and then to Co 0 is observed, which is consistent with the results of H 2 -temperature programmed reduction. During the reduction the two steps occur concurrently. The deconvolution of the Co 2p core level state for the catalyst reduced at 385 °C and 1.0 × 10 −6 Torr of H 2 revealed signatures of Co 0 , CoO, and Co 3 O 4 . The reduction saturates at a Co o concentration of approximately 41% after 20 h, which correlates with the activity and lifetime of the catalyst during FTS testing. Conversely, at 680 °C and 10 Torr of H 2 , the catalyst is completely reduced after 10 h. The evolution of the Co d-band at the Fermi level in the valence band XPS spectrum definitively verifies the metallic phase of Co. FTS evaluation of the Co/NS catalyst reduced at 609 °C showed higher production rate (3-fold) of C 6 -C 17 hydrocarbons than the catalyst reduced at 409 °C and is consistent with the XPS analysis. [ABSTRACT FROM AUTHOR]

Hydrothermal treatment (HTT) was used to convert residual bacterial biomass (RBB), recovered from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production, into valuable bioproducts. The effect of processing temperatures (150, 200, and 250 °C) on the bioproducts (water-solubles (WSs), bio-oil, insoluble residue, and gas) was investigated. The yields of bio-oil and gas were higher at higher temperatures. The maximum WS content (28 wt%) was obtained at 200 °C. GCMS analysis showed higher content of aromatics and N-containing compounds with increasing temperature. ESI-MS revealed chemical compounds (e.g. protein, carbohydrate, lipids, and lignin) associated with RBB are fragmented into smaller molecules (monomers) at higher HTT temperatures. The WS fraction contained totally 838, 889 and 886 mg/g acids and 160, 31 and 21 mg/g carbohydrate for HTT at 150, 200, and 250 °C, respectively. The solid residues contain unconverted compounds, especially after HTT at 150 °C. The WS products (acids and carbohydrates) could be used directly for PHA biosynthesis. [ABSTRACT FROM AUTHOR]

This study evaluates the potential of a mixed fast and slow pyrolysis process for the conversion of four feedstocks (i.e., hybrid poplar, maple, pine, and sugarcane bagasse) into bio-oil and biochar. The novelty of this study lies within the integration of a free-fall reactor with a batch reactor to take advantage of both fast and slow pyrolysis, and adapt conversion parameters (e.g., carrier gas pressure, feedstock particle size, bulk density, reactor height, and path tortuosity) to maximize the desired product quality and yields. Thermogravimetric analysis was used to provide insight into the thermal degradation of the specified feedstock. Biomass samples were pyrolyzed at 500–550 °C, and the conversion products were evaluated. Biochar properties were characterized using proximate and ultimate analyses and surface area. Bio-oil characterization was obtained by gas chromatography-mass spectrometry (GC-MS), electrospray ionization-mass spectrometry (ESI-MS), Fourier transform infrared (FTIR) spectroscopy, and thermal stability testing. GC-MS identified dominant bio-oil compounds, such as levoglucosan, furfural, and acetic acid. ESI detected molecular weights that are higher than average, necessitating further in-situ cracking (e.g., thermal or catalytic). FTIR showed similar peak patterns and functional groups across the feedstock. The results show that maple produced the greatest biochar yield at 56%, while hybrid poplar had the greatest bio-oil yield at 38%. Among the feedstocks, bio-oil produced from hybrid poplar presents a promising oil with the lowest moisture content (<20%), high phenol content, and the most thermally stable properties, while bio-oil from pine had the next best thermal stability, but with the highest content of levoglucosan (a favorable platform molecule). Analytical results are compared to prior studies to identify the advantages and disadvantages of the free-fall fast pyrolysis reactor. Shortcomings of the current reactor configuration are identified, along with the direction for future studies. • This study evaluates the potential of a mixed fast and slow pyrolysis process. • Four feedstocks of varying characteristics are pyrolyzed and products examined. • Fast Pyrolysis was carried out in a free-fall reactor operating at 500–550 °C. • Quality and yield were dependent on biomass particle size and feedstock type. • Pine and hybrid poplar produced bio-oil with best stability and chemical properties. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoate (PHA) production generates a significant amount of residual bacterial biomass (RBB) after PHA extraction. The RBB as a zero-value waste contains proteins, carbohydrates, phenolics, and ash, which can be managed and converted to bio-oil and biochar products by pyrolysis. Thermogravimetric analysis (TGA) was used to investigate the thermodegradation kinetics of RBB and pyrolysis–GCMS studies were employed to determine potential chemical products. Pyrolysis was conducted on a laboratory-scale auger reactor at 500 °C. The bio-oil and biochar yield were 28 and 46%, respectively. The pyrolysis bio-oil was characterized by the combination of GCMS, high-pressure liquid chromatography (HPLC), and electrospray ionization mass spectrometry (ESI–MS). The bio-oil was dominated by nitrogen-containing, hydrocarbons, and aromatic compounds. The biochar was studied for its specific surface area and pore size, chemical functionality by Fourier transform infrared (FTIR) and Raman spectroscopies, and butane absorption activity. Biochar was comprised of a large part of polycondensed phenolic and majorly disordered amorphous carbon. [ABSTRACT FROM AUTHOR]

Three undefined mixed cultures (activated sludge) from different municipal wastewater treatment plants were used as seeds in a novel lactic acid fermentation process fed with potato peel waste (PPW). Anaerobic sequencing batch fermenters were run under identical conditions to produce predominantly lactic acid. Illumina sequencing was used to examine the 16S rRNA genes of bacteria in the three seeds and fermenters. Results showed that the structure of microbial communities of three seeds were different. All three fermentation products had unique community structures that were dominated (>96%) by species of the genus Lactobacillus , while members of this genus constituted <0.1% in seeds. The species of Lactobacillus sp. differed among the three fermentations. Results of this study suggest the structure of microbial communities in lactic acid fermentation of PPW with undefined mixed cultures were robust and resilient, which provided engineering prospects for the microbial utilization of carbohydrate wastes to produce lactic acid. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the potential of using wood hydrolysates (enzymatically hydrolyzed from hybrid poplar) as substrate to produce polyhydroxybutyrate (PHB) using mixed microbial cultures. The optimal operational conditions for fed-batch bioreactors were 4 d solid retention time with an organic loading rate of 2.5 g/Ld. The maximum PHB accumulated was 27% of cell dry weight with a yield of 0.32 g/g (g PHB produced per g sugars consumed). Microbial community analysis was done at the genus level by 16S rRNA sequencing on an Illumina system and community evolution was observed among different samples and initial seed. Actinobacteria , Alpha- and Beta-proteobacteria were found to be the dominant groups in all the bioreactors. Several PHB-storing microorganisms were characterized belonging to Alpha- and Beta-proteobacteria . [ABSTRACT FROM AUTHOR]

Torrefaction enhances physical properties of lignocellulosic biomass and improves its grindability. Energy densification, via fuel pellets production, is one of the most promising uses of torrefaction. Lignin contributes to self-bonding of wood particles during pelletization. In biomass thermal pretreatment, part of lignin (in the form of lignin liquid intermediates – LLI) migrates from the cell wall and middle lamella and deposits on the fibers’ surfaces and/or inner surface of the secondary cell wall. This material can play an important role on bonding particles during wood pelletization as well as production of wood composites. The objective of this paper was to investigate the influence of torrefaction conditions on amount, composition, molecular weight, and pattern of deposition of LLI on wood cells. Torrefaction of extracted ponderosa pine in the range of temperatures 225–350 °C was conducted in a tube furnace reactor and the torrefied wood was extracted with dichloromethane (DCM) to isolate the lignin-rich soluble material. A maximum yield of DCM-soluble material was observed in wood torrefied at approximately 300 °C for 30 min. ESI/MS revealed that the molecular weight of the removed material is less than 1200 g mol −1 and decreases as torrefaction temperature augments. Semiquantitative Py-GC/MS of the DCM-soluble material suggests that this lignin-rich material migrates and deposits on cells’ surfaces in amounts that depend on the torrefaction conditions. Py-GC/MS of the solid fraction after the DCM process showed a progressive reduction of products of the pyrolysis of lignin and levoglucosan as torrefaction temperature increased, revealing that lignin content in the solid decreased due in part to migration. SEM of torrefied particles helped to show the apparent formation of LLI during torrefaction. Results suggest that it is possible to control the thermal pretreatment conditions to increase or reduce the amount of lignin-rich material on fiber surfaces as required for downstream processes (e.g., fuel pellets or wood composites manufacture). [ABSTRACT FROM AUTHOR]

Pyrolysis of polypropylene (PP) with an equilibrium fluid catalytic cracking (FCC) catalyst in a stirred reactor was studied to produce “fuel like” hydrocarbons. The effect of process parameters such as degradation temperature, catalyst/polymer ratio (%), carrier gas type and stirrer rate on the condensed product yield and composition were determined. Reaction products were determined by GC analysis and shown to contain naphthenes, paraffins, olefins and aromatics. Temperature was shown to influence PP cracking. The addition of the catalyst has improved the economic viability of the process to produce light hydrocarbons. PP pyrolysis showed the maximum condensed product yields at 450 °C and 10% catalyst respectively. Hydrogen as a reactive carrier gas increased the condensed and paraffinic product yield. The results showed that reactive carrier gases can affect on the product yield and composition patently. Appropriate heat transfer – by stirring – can increase the catalyst efficiency in a stirred reactor. [ABSTRACT FROM AUTHOR]

The formation of liquid intermediates and the distribution of products were studied under slow and fast pyrolysis conditions. Results indicate that monomers are formed from lignin oligomeric products during secondary reactions, rather than directly from the native lignin. Lignin from Douglas-fir (Pseudotsuga menziesii) wood was extracted using the milled wood enzyme lignin isolation method. Slow pyrolysis using a microscope with hot-stage captured the liquid formation (>150 °C), shrinking, swelling (foaming), and evaporation behavior of lignin intermediates. The activation energy (E a) for 5–80% conversions was 213 kJ mol−1, and the pre-exponential factor (log A) was 24.34. Fast pyrolysis tests in a wire mesh reactor were conducted (300–650 °C). The formation of the liquid intermediate was visualized with a fast speed camera (250 Hz), showing the existence of three well defined steps: formation of lignin liquid intermediates, foaming and liquid intermediate swelling, and evaporation and droplet shrinking. GC/MS and UV-Fluorescence of the mesh reactor condensate revealed lignin oligomer formation but no mono-phenols were seen. An increase in pyrolytic lignin yield was observed as temperature increased. The molar mass determined by ESI-MS was not affected by pyrolysis temperature. SEM of the char showed a smooth surface with holes, evidence of a liquid intermediate with foaming; bursting from these foams could be responsible for the removal of lignin oligomers. Py-GC/MS studies showed the highest yield of guaiacol compounds at 450–550 °C. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pyrolysis of beech wood particles (0.3 and 14mm). [•] The yield of pyrolytic lignin decreased as particle size increased. [•] Two different pyrolysis regimes were confirmed between 0.3 and 14mm. [•] Secondary reactions and mass transfer limitations lead to more char. [Copyright &y& Elsevier]

Abstract: This paper investigates the effect of sulfuric acid (H2SO4) concentration, as an additive to enhance the production of anhydrosugars via pyrolysis of Douglas-fir, on the yield and composition of the lignin derived oligomers. Pyrolysis tests at 500°C were conducted in auger and fluidized bed reactors. For both reactors the yield of lignin derived oligomers decreased as H2SO4 was added. Several analytical techniques (UV-fluorescence, TGA, ESI-MS, FTIR, solid state 13C NMR and Pyrolysis-GC/MS) were used to characterize the lignin derived oligomers collected. Four peaks were observed in the UV-fluorescence spectra. The addition of H2SO4 reduces the yield of all the peaks. DTG curves also show the presence of several peaks. The addition of H2SO4 decreased the yield of all the peaks but its effect was more pronounced on peaks at 320 and 400°C. Electrospray ionization-mass spectrometry studies did not show any major change on the molecular weight of the lignin oligomers ionized products obtained as a function of H2SO4 concentration. Solid state NMR results indicate that the methoxyl groups decreased and the carbonyl increased gradually as sulfuric acid concentration increases. The Py-GC/MS confirmed the phenolic compounds with methoxyl substitutions were substantially reduced as the acid concentration increased. The experimental results obtained suggest the presence of H2SO4 enhances the polycondensation of methoxyl substituted aromatic rings. [Copyright &y& Elsevier]

We present a convolutional neural network (CNN) framework for classifying different types of plastic materials that are commonly found in mixed plastic waste (MPW) streams. The CNN framework uses experimental ATR-FTIR (attenuated total reflection-Fourier transform infrared spectroscopy) spectra to classify ten different plastic types. An important aspect of this type of spectral data is that it can be collected in real-time; as such, this approach provides an avenue for enabling the high-throughput characterization of MPW. The proposed CNN architecture (which we call PlasticNet) uses a Gramian angular representation of the spectra. We show that this 2-dimensional (2D) matrix representation highlights correlations between different frequencies (wavenumber) and leads to significant improvements in classification accuracy, compared to the direct use of spectra (a 1D vector representation). We also demonstrate that PlasticNet can reach an overall classification accuracy of over 87% and can classify certain plastics with 100% accuracy. Our framework also uses saliency maps to analyze spectral features that are most informative. • Present a convolutional neural net (CNN) framework for plastic classification. • Approach uses ATR-FTIR spectra to classify plastics. • Combination of CNN and ATR-FTIR provides avenue to enable sorting of mixed plastic waste. [ABSTRACT FROM AUTHOR]

The plastic waste accumulation has been increasing and a solution other than landfilling is required. Due to the high cost of recycling, thermal treatment could be an option. However, the existence of polyvinyl chloride (PVC) would release hydrochloric acid which would cause emission problems as well as damage to the reactor systems. The thermal degradation of PVC has been studied over the years. However, the mechanism of the PVC thermal degradation is not fully developed. Specifically, the mechanism of the PVC thermal degradation at medium temperatures, which is more practical for industries, is still lacking. A degradation temperature of 300 °C was used to study the dehydrochlorination behavior of PVC. A rather comprehensive mechanism with four consecutive reactions has been developed based on the micro-pyrolysis experiments and has been validated and proved by predicting the mass loss, chlorine content, heat content and elemental composition with high precision experimental data in different reactors with/without heat transfer coupling. • A four consecutive reaction mechanism was developed for PVC degradation at 300 °C. • The mechanism was based on the release of HCl, benzene, naphthalene and anthracene. • The mechanism was proved by predicting Cl/H/C/heat-content data in other reactors. [ABSTRACT FROM AUTHOR]

• Corrugated cardboard (CCB) was evaluated as a potential feedstock for energy recovery • Pyrolysis of the CCB was carried in an auger reactor (350, 400, and 450 °C) • Pyrolysis biochar and bio-oil yields were temperature dependent • Pyrolysis bio-oil mainly contained lipids and levoglucosan. As the most abundant municipal solid waste, corrugated cardboard (CCB) is a suitable resource for thermochemical conversion into various solid and liquid products. CCB samples were pyrolyzed at three temperatures (350, 400, and 450 °C) and their pyrolysis products (bio-oil and biochar) were characterized and analyzed. Thermogravimetric analysis (TGA) was utilized to study the thermal degradation behavior of CCB. CCB and biochar samples were subjected to proximate, ultimate, lipid and carbohydrates analyses, and Py–GCMS to characterize their chemical components. The highest biochar yield was 75% at 350 °C, and the highest bio-oil yield was 47% at 450 °C. The biochar physical and chemical properties were also assessed using calorific values, specific surface area, Fourier-transform infrared (FTIR) and Raman spectroscopies, and x-ray diffraction (XRD). Biochar was found to have low ash and nitrogen contents. The bio-oil was characterized by the combination of GCMS, high-performance liquid chromatography (HPLC), and electrospray ionization mass spectrometry (ESI–MS). The molar mass distribution and an estimate of monomer/oligomer ratio were determined from ESI-MS data. The bio-oil contained a complex mixture of pyrans, furans, phenols, and cyclopentenes. Levoglucoson was abundantly found in the bio-oil, suggesting the suitability of cardboard pyrolysis products for further processing into fuels. [ABSTRACT FROM AUTHOR]