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The increased rate of postuse accumulation of the heteroatom‐containing plastic wastes, like polyethylene terephthalate (PET), polycarbonate (PC) and polyurethane (PU), in the environment propels the research for effective and sustainable valorization. In this study, PET from bottle waste, PC from compact discs, and PU from waste wind turbine blade were characterized and employed for fast pyrolysis experiments. Importantly, red mud (RM), a mixed oxide rich in Fe, Al, Si, Na, and Ca, was used as a catalyst for fast pyrolysis. The effects of temperature and feed/catalyst ratio on product yields were studied to elucidate the product formation mechanism. Benzoic acid and its derivatives, bisphenol‐A and oxygenated aromatics, and 4,4′‐methylenebisbenzamine were the major products obtained from the noncatalytic fast pyrolysis of PET, PC, and PU, respectively. The use of RM improved the yield of aromatic hydrocarbons from PET to 27.8 wt% at 550 °C, phenolics from PC to 46.6 wt% at 550  °C, and 4,4′‐methylenebisbenzamine to 34.9 wt% at 650 °C. The catalytic activity of RM is ascribed to the presence of active basic sites. The present study paves the path for the catalytic upcycling of challenging plastic wastes using industrial waste, like RM, as a sustainable catalyst from a circular economy viewpoint. [ABSTRACT FROM AUTHOR]

The upgrading of pyrolysis deoxygenation of polyester/viscose fibers was examined in this paper utilizing montmorillonite (MMT) catalysts with varying ratios and amounts of tungsten-manganese bimetallic. The temperature-programmed desorption of NH3 (NH3-TPD) revealed that after tungsten-manganese bimetal loading, MMT formed novel acidic sites, resulting in a considerable rise in total acidity. The maximum aromatics yield (73.10%) was achieved by the MMT with a bimetal loading of 10 wt%, the yield of monocyclic aromatic hydrocarbons (MAHs) was highest at 40.38%, while the yield of polycyclic aromatic hydrocarbons (PAHs) was lowest. The MAHs yield dramatically dropped at 15 wt% and 20 wt% bimetal loading. The application of a moderate load has the potential to facilitate the generation of MAHs, whilst an excessive load can readily facilitate the development of PAHs. The acid equilibrium of MMT was enhanced following the application of varying ratios of tungsten-manganese bimetal loading. When the ratio of bimetal load was 1:1, a significant synergistic impact was seen, resulting in a substantial enhancement of the catalyst regulation performance on MAHs and PAHs. Specifically, the catalyst exhibited a tendency to generate a higher proportion of useful MAHs (40.38%) while simultaneously reducing the production of PAHs (32.72%). This phenomenon can be attributed to the appropriate pore structure and the equitable distribution of Lewis acid and Brønsted acid sites within the pores. [ABSTRACT FROM AUTHOR]

The catalytic fast pyrolysis process is a promising method for converting biomass waste into bio-oil, where the catalyst plays a crucial role in determining the yield and quality of the products. In this study, ultrafine iron nanoparticles were incorporated onto a montmorillonite substrate through the pyrolyzing coordinated polymer method to enhance liquid fuel production via catalytic pyrolysis of biomass waste. The catalyst showed a uniform distribution of iron on the montmorillonite surface, indicating that the incorporation was successful. Catalytic pyrolysis led to an increase in liquid yields and a decrease in gas product yields compared to direct pyrolysis. The highest bio-oil yield obtained was 56.9% during the catalytic pyrolysis of corncob, which was found to be particularly well-suited for the production of bio-oil. Furthermore, the proposed reaction pathway was based on identifying the composition of the bio-oil, which was further supported by quantum chemical calculations of chemical bond strength and the likelihood of free radical attacks. These findings demonstrate the potential of using montmorillonite-supported ultrafine iron nanoparticles to enhance bio-oil yield and quality in biomass pyrolysis processes.

Lignin, an abundant renewable biopolymer found in plant cell walls, is enriched in phenolic units within its complex molecular structure. Unlocking its potential as alternative feedstock in (bio)refining has posed a long-standing challenge, even though it holds immense promise for replacing fossil-derived phenolic and aromatic compounds. This study focuses on fast pyrolysis as effective thermochemical depolymerization method of lignin, coupled with the in situ catalytic upgrading aiming to produce valuable bio-oil enriched in dealkoxylated (alkyl)phenolic and aromatic compounds. Lignin was isolated via the organosolv process from beechwood sawdust (hardwood biomass). Various acidic aluminosilicate catalysts (e.g., zeolites, such as ZSM-5, Beta and USY, and amorphous silica alumina) were applied, having different Si/Al ratio, porous and acidic properties. Fast pyrolysis experiments were conducted on a fixed-bed bench-scale reactor at two distinct temperatures (500 and 600 °C), employing different contact times and lignin-to-catalyst ratios. Non-catalytic pyrolysis experiments revealed that higher temperature, significantly influences bio-oil’s composition and yield, resulting in the conversion of initially formed alkoxy-phenols to alkyl-phenolic compounds, reaching a 47% relative concentration at 600 °C, while also yielding high amount of bio-oil up to 43 wt%. Among the catalysts tested, zeolite ZSM-5 (Si/Al=40) proved to be the most efficient, shifting the chemical profile of bio-oil from phenolic to aromatic (mainly BTX) with relative concentration of 57%, owing to its unique microporous structure and acidity. Depending on the catalyst type, a balance between BTX monomer aromatics and naphthalenes was observed. Lignin, as well as the obtained products (bio-oil, non-condensable gases, char/coke-on-catalyst) were thoroughly characterized using various analytical techniques. The catalytic upgrading results were associated with the physicochemical properties of the catalysts, providing valuable insights into the underlying reaction mechanisms.

Dolomite as the catalyst for pyrolysis of waste cooking oil (WCO) was investigated to produce hydrocarbon fuels. Optimization of pyrolysis parameters i.e. time, temperature and catalysts loading, achieved high selectivity of WCO to diesel hydrocarbon, compared to thermal pyrolysis that produced mainly carboxylic acids. Dolomite catalysed deoxygenation of fatty acid in WCO into hydrocarbon, consequently accelerating the pyrolysis time to 75 min. Bio-oil at 68.06% yield with 57.27% selectivity towards diesel and gasoline hydrocarbons was obtained at 450 °C while using 6% of dolomite. Dolomite exhibited partial phase separation into dolomite/CaCO3 mixtures within 15 min of pyrolysis, initiated by the generated CO2 during pyrolisis of WCO. The catalyst is stable for up to three reaction cycles suggesting the activity was achieved from the synergy between the dolomite/CaCO3 phases.

This research aimed processing of Leucaena Leucocepphala in a fluidized-bed reactor with catalysts for renewable energy. The reaction was tested over different type of catalysts such as natural zeolite, kaolin and dolomite. These catalysts were loaded under the heating zone with a supplementary hot filter. The rate of feedstock added in the reactor was 1 kg/h and the pyrolysis temperature was 500 °C. Product yields was calculated after each experiment was completed.The results demonstrated an optimum bio-oil yield of 65.1 wt% after undergoing fast pyrolysis. A reduction in bio-oil yield was observed when natural zeolite, kaolin and dolomite was employed during fast pyrolysis. The minimum bio-oil yield recorded for the dolomite catalyst was 54.5 wt%. On the other hand, kaolin catalyst produces a maximum bio-oil yield of 59.6 wt%. The organic content of bio-oil from kaolin catalyst increased significantly compared with other catalysts. Addition of an ESP condenser, instead of water-cooled condenser resulted in bio-oil with the highest heating value (HHV). Higher heating value of bio-oil derived from natural zeolite catalyst maximized at 35.8 MJ/kg and 37.3 MJ/kg, respectively. The range of hydrocarbon component of bio-oil was C15–C44 for ESP condenser and C12–C35 for water-cooled condenser. The availability of bio-oil was optimized when natural zeolite catalyst added into the process. On the other hand, density and viscosity of bio-oil was increased when dolomite catalyst was used. Additionally, the presence of dolomite catalyst reduced acidic compounds such as 2-Octenoic acid (C8H14O2) and Methyl propiolate (C4H4O2) in the bio-oil. Bio-oil yield was found to be significantly improved by the large pore diameter and small surface area of the catalyst. Among the three catalysts in was observed that kaolin catalyst gave the highest bio-oil yield. Natural zeolite catalyst was found to improved bio-oil product’s thermal quality. However, bio-oil with better viscosity and lower acidity was produced from the dolomite catalyst.

A niobium-doped HZSM-5 (H[Nb]ZSM-5) was prepared by a hydrothermal synthesis method. The morphology, phase structure, composition, pore structure, and acid content of the catalyst were characterized using a series of analysis techniques such as scanning electron microscope (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption, and temperature programmed desorption measurements (NH3-TPD). The H[Nb]ZSM-5 catalyst fully remained within the crystal framework and pore structure of HZSM-5. Meanwhile, introduction of niobium (V) endowed the catalyst with both Lewis acid and Bronsted acid sites. Catalytic fast pyrolysis (CFP) of alkali lignin was carried out through a pyrolysis and gas chromatography-mass spectrometry (Py-GC/MS) at 650 °C and atmospheric pressure. The results indicated that H[Nb]ZSM-5 can efficiently and selectively convert lignin into monoaromatic hydrocarbons (MAHs), compared to the control HZSM-5. Catalyzed by H[Nb]ZSM-5, the content of MAHs and aliphatic hydrocarbons reached 43.4% and 20.8%, respectively; while under the catalysis of HZSM-5, these values were 35.5% and 3.2%, respectively. H[Nb]ZSM-5 remarkably lowered the phenol content to approximately 2.8%, which is far lower than the content (24.9%) obtained under HZSM-5 catalysis. [ABSTRACT FROM AUTHOR]

Catalytic fast pyrolysis (CFP) for biomass treatment is a research hotspot but there is little information about the difference between the in situ and ex situ methods. In present work, the Ni–Fe/CaO–Al2O3 catalysts with different Ni/Fe ratios have been synthesized by coprecipitation method, and the product distribution about the Chinese herb residue (CHR) catalytic fast pyrolysis by in situ and ex situ methods in a quartz tube reactor system has been investigated. The results show that the CFP pyrolysis would upgrade the quality of bio-oil but decrease the yields, no matter in situ or ex situ CFP process. During the in situ CFP process, heteroatoms may be absorbed by the catalyst support and cannot be transferred to the bio-oil, but the results of ex situ CFP are the opposite. In addition, the ex situ CFP reaction significantly increases the content of aromatic hydrocarbons. As to the gas products' distribution, the effect of Fe in catalysts to promote CH4 formation is reflected in in situ CFP process, while the promotion effect of H2 generation for Ni added in catalyst is mainly reflected in ex situ CFP process. However, due to the high reaction temperature (800 °C), the adsorption of CO2 by CaO support is not particularly significant. The possible mechanism of CHR in CFP process has also been summarized for understanding the process of in situ and ex situ CFP, and this study may provide a choice or reference for CHR treatment. [ABSTRACT FROM AUTHOR]

Given the outstanding selective catalytic and deoxygenation abilities of ZSM-5, it has a great potential to enrich aromatics in catalytic biomass pyrolysis to oil, while metal oxides as catalysts have the ability to reduce the molecular size of compounds, which can weaken the limitation of ZSM-5 to macromolecular intermediates. In this study, metal oxides and ZSM-5 were chosen as catalysts to further extend the advantages of selective catalysis. In this paper, microscopic and bench-scale experiments for the conversion of biomass to high-yield aromatics using ZSM-5 and metal oxide catalysts were systematically investigated. In a dual catalyst pyrolysis study involving ZSM-5 and metal oxides (CaO, MgO, NiO, MoO 3), PY-GC-MS, Tube Furnace experiments were used to evaluate various catalyst layouts. The influence of catalyst dose on three-phase product yields was examined in a bench-scale fixed bed reactor employing the optimal architecture and metal oxides. The findings revealed that the dual-catalyst arrangement was critical to improving bio-oil quality. The best yield (50.02 %) of monocyclic aromatic hydrocarbons (MAHs) was produced by combining Miscanthus with the metal oxides and then separating with ZSM-5. Among the four metal oxides, CaO had the greatest synergistic effect on MAHs and selectivity. The inclusion of CaO decreased the concentration of several oxygenated compounds, particularly the suppression of furans, phenols, and acids, which was extremely advantageous for improving bio-oil quality. The highest percentage of hydrocarbon production (64.61 %) in bio-oil was produced at a Miscanthus to CaO to ZSM-5 ratio of 1:2:4, however increasing catalyst dose reduces bio-oil yield (28.92 %). • Metal oxides will adhere to the outer surface of ZSM-5, leading to pore blockage. • CaO and ZSM-5 have the highest synergistic effect as catalysts together. • CaO inhibits the production of oxygenated compounds that can produce PAHs. • A proper increase in catalyst dose can balance the yield and quality of bio-oil. [ABSTRACT FROM AUTHOR]

• 100% conversion of 2-butanone to sec -butyl isopropyl ether was achieved. • Cu/Char and H-Beta exhibited the best catalytic activity. • Mass yield of long-chain ethers increased from 53.94 % at 1 h to 62.86 % at 12 h. • Low temperature heat release was from −15°CA for n -heptane to –23.5°CA for LE30. The work introduced an innovative pathway for converting biomass-derived carbonyls into long-chain ethers, examining their low-temperature oxidation in a modified Cooperative Fuel Research (CFR) engine. The conversion of 2-butanone achieved 100 % and the selectivity of sec -butyl isopropyl ether reached the maximum of 83.13 % under optimal reaction conditions. Conversion of biomass-derived carbonyls increased from 31.77 % at 1 h to 36.28 % at 12 h, with the mass yield of long-chain ethers rising from 53.94 % to 62.86 %. At the same compression ratio, the maximum in-cylinder pressure and temperature increased as the long-chain ethers blending ratio increased. At the critical compression ratio, the net heat release rates (NHR) for blended fuels with 10 vol%, 20 vol% and 30 vol% long-chain ethers at the low-temperature heat release peak were 9.6 J/deg, 10.1 J/deg, and 10.0 J/deg better than that of n -heptane (6.3 J/deg), respectively. CO emissions from blended fuels before compression ignition were higher than n -heptane, while the value for the blended fuel with 30 vol.% long-chain ethers was reduced by 44.97 % compared to n -heptane after autoignition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimized parameters for stepwise pyrolysis are systematically investigated. • Low-temperature pyrolysis section is beneficial to biomass decomposition. • High-temperature pyrolysis section realizes the deoxygenation of intermediates. • Stepwise pyrolysis improves both the bio-oil yield and hydrocarbons selectivity. Stepwise pyrolysis is recognized as a promising method in converting biomass into sustainable bio-oils. However, a systematic study on the stepwise parameters (e.g. , low- and high-pyrolysis temperatures, duration, atmosphere) is still lacking. Herein, the stepwise catalytic fast pyrolysis (CFP) of cotton stove over ZSM-5 was conducted, aiming to reveal the impact of aforementioned parameters on bio-oils production. Results showed that the low-temperature pyrolysis benefitted the decomposition of biomass, while the high-temperature counterpart favored the upgrading of bio-oil. The combination of a low-temperature pyrolysis (400 ℃ for 2 min) and high-temperature pyrolysis (600 ℃ for 3 min) led to a satisfied hydrocarbons selectivity (35.8 area%) and bio-oil yield (11.4 wt%). This was superior to the one-step pyrolysis conducted at 600 ℃ for 5 min, which decreased the values to 32.2 area% and 11.2 wt%, respectively. The CO 2 introduction into N 2 atmosphere in stepwise pyrolysis further enhanced the hydrocarbon-rich bio-oil production, and a maximum bio-oil yield of 15.9 wt% was obtained in 100 vol% CO 2 , while the highest hydrocarbons selectivity of 51.8 area% was reached in 80 vol% CO 2. This work confirmed the advantages of stepwise pyrolysis for producing high-quality bio-oils and provided a reference for pyrolysis in CO 2 atmosphere. [ABSTRACT FROM AUTHOR]

The management of municipal and industrial organic solid wastes has become one of the most critical environmental problems in modern societies. Nowadays, commonly used management techniques are incineration, composting, and landfilling, with the former one being the most common for hazardous organic wastes. An alternative eco-friendly method that offers a sustainable and economically viable solution for hazardous wastes management is fast pyrolysis, being one of the most important thermochemical processes in the petrochemical and biomass valorization industry. The objective of this work was to study the application of fast pyrolysis for the valorization of three types of wastes, i.e., petroleum-based sludges and sediments, residual paints left on used/scrap metal packaging, and creosote-treated wood waste, towards high-added-value fuels, chemicals, and (bio)char. Fast pyrolysis experiments were performed on a lab-scale fixed-bed reactor for the determination of product yields, i.e., pyrolysis (bio)oil, gases, and solids (char). In addition, the composition of (bio)oil was also determined by Py/GC-MS tests. The thermal pyrolysis oil from the petroleum sludge was only 15.8 wt.% due to the remarkably high content of ash (74 wt.%) of this type of waste, in contrast to the treated wood and the residual paints (also containing 30 wt.% inorganics), which provided 46.9 wt.% and 35 wt.% pyrolysis oil, respectively. The gaseous products ranged from ~7.9 wt.% (sludge) to 14.7 (wood) and 19.2 wt.% (paints), while the respective solids (ash, char, reaction coke) values were 75.1, 35, and 36.9 wt.%. The thermal (non-catalytic) pyrolysis of residual paint contained relatively high concentrations of short acrylic aliphatic ester (i.e., n-butyl methacrylate), being valuable monomers in the polymer industry. The use of an acidic zeolitic catalyst (ZSM-5) for the in situ upgrading of the pyrolysis vapors induced changes on the product yields (decreased oil due to cracking reactions and increased gases and char/coke), but mostly on the pyrolysis oil composition. The main effect of the ZSM-5 zeolite catalyst was that, for all three organic wastes, the catalytic pyrolysis oils were enriched in the value-added mono-aromatics (BTX), especially in the case of the treated wood waste and residual paints. The non-condensable gases were mostly consisting of CO, CO2, and different amounts of C1–C4 hydrocarbons, depending on initial feed and use or not of the catalyst that increased the production of ethylene and propylene.

The aim of this research is to design and synthesize an efficient catalyst to enhance high value-added products, such as aromatic hydrocarbons and phenols, from the catalytic fast pyrolysis (CFP) of different types of forestry and agricultural residues. All three biomasses (rape straw, wheat straw, and bamboo powder) had no aromatic production via thermal pyrolysis alone; however, the aromatic selectivity and monocyclic aromatic selectivity were largely enhanced using ZSM-5, with suitable silica-alumina ratios and Ni loadings. Specifically, for rape straw, the optimum catalyst was 15 wt.% Ni/ZSM-5 (silica-aluminum ratios = 85), and the selectivity of aromatic hydrocarbons was achieved at 39%, of which 71% were monocyclic aromatic hydrocarbons. For wheat straw, the optimum catalyst was 10 wt.% Ni/ZSM-5 (silica-aluminum ratios = 18), and the selectivity of aromatic hydrocarbons was 67%, of which 55% were monocyclic aromatic hydrocarbons. For bamboo powder, the optimum catalyst was 10 wt.% Ni/ZSM-5 (silica-aluminum ratios = 18), and the selectivity of aromatic hydrocarbons was achieved at 21%, of which 80% were monocyclic aromatic hydrocarbons. Meanwhile, biomass types have significant effects on the pyrolyzed product distribution due to their different components. Cellulose and hemicellulose promoted the production of aromatic hydrocarbons, while lignin enhanced the production of phenols. The promotion of phenol by Ni was better and more efficient than that by the molecular sieve. [ABSTRACT FROM AUTHOR]

In this study, three type of pretreatment methods (single pretreatment of leaching, single pretreatment of torrefaction, combined pretreatment of leaching and torrefaction) were employed to improve the quality of rice straw. Three leaching agents, namely acid solution, phenol solution, and simulated light bio-oil (SBO), were used. Then, in order to obtain higher yield of benzene, toluene, and xylene (BTX), the pretreated biomass was pyrolyzed using Py-GC/MS. Effects of combined pretreatment (leaching and torrefaction) and shape selective catalytic fast pyrolysis (SS-CFP) on the production of aromatics were investigated. Results showed that the combined pretreatments have advantages of the separate pretreatments, that is, deashing and deoxygenation. Synergistic effect was found between acids and phenols in SBO with respect to the removal of alkali and alkaline earth metal species (AAEMs) from rice straw. This promotes the generation of volatile substances, which are upgraded to produce BTX under catalysis of HZSM-5. Among the pretreated samples, torrefied–leached samples have the highest selectivity for BTX (64.6%). In conclusion, combined pretreatment of leaching and torrefaction was more effective to improve the yield of BTX than the single pretreatment of leaching or torrefaction.

In this study, a computational fluid dynamics mathematical model has been developed for catalytic fast pyrolysis (CFP) of biomass based on multiphase flow, transfer process, and biomass pyrolysis reactions in a bubbling fluidized bed reactor. The multiphase fluid flow, and the inter‐phase momentum and energy transfer processes are modeled with Eulerian multiphase formulas, representing the flows of gases and solids (catalyst and biomass) within the reactor. The biomass CFP reactions are described by using a two‐stage, semi‐global model. Specified secondary tar catalytic cracking process, which considers both intrinsic reaction rates and mass‐transfer process, is embedded to the developed model by user‐defined function. The model simulation results of pyrolysis product yield and distribution are compared with the experimental data with close agreement. The model is then employed to investigate the effects of structural properties of catalyst, such as specific internal area, average size of active sites, pore diameter, and tortuosity, on products yields and composition. The tar cracking process by the selected catalyst is proposed and the influences of adsorption capability of tar molecule on catalyst surface and external film mass transfer are also analyzed. The developed model can be solved with short computational time and thus it can be employed for further research and engineering designs of the catalytic pyrolysis of carbonaceous materials. [ABSTRACT FROM AUTHOR]

A niobium-doped HZSM-5 (H[Nb]ZSM-5) was prepared by a hydrothermal synthesis method. The morphology, phase structure, composition, pore structure, and acid content of the catalyst were characterized using a series of analysis techniques such as scanning electron microscope (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption, and temperature programmed desorption measurements (NH3-TPD). The H[Nb]ZSM-5 catalyst fully remained within the crystal framework and pore structure of HZSM-5. Meanwhile, introduction of niobium (V) endowed the catalyst with both Lewis acid and Bronsted acid sites. Catalytic fast pyrolysis (CFP) of alkali lignin was carried out through a pyrolysis and gas chromatography-mass spectrometry (Py-GC/MS) at 650 °C and atmospheric pressure. The results indicated that H[Nb]ZSM-5 can efficiently and selectively convert lignin into monoaromatic hydrocarbons (MAHs), compared to the control HZSM-5. Catalyzed by H[Nb]ZSM-5, the content of MAHs and aliphatic hydrocarbons reached 43.4% and 20.8%, respectively; while under the catalysis of HZSM-5, these values were 35.5% and 3.2%, respectively. H[Nb]ZSM-5 remarkably lowered the phenol content to approximately 2.8%, which is far lower than the content (24.9%) obtained under HZSM-5 catalysis.

Catalytic fast pyrolysis is considered as a promising technology for converting biomass into biofuels. In the present research, a series of NbO x modified ZSM-5 catalysts were developed and applied for the selective fast pyrolysis of corncob into aromatics. Depolymerization and hydrodeoxygenation of lignin constituents as well as the aromatization of polysaccharide fractions were the major source of aromatics. The introduction of niobium oxide into ZSM-5 remarkably enriched the Lewis acids and improved the porous structures. The presence of synergistic effect between acid sites and porous structure of NbO x modified ZSM-5 contributed to the aromatics formation in a certain degree. Under the catalysis of 3Nb/ZSM-5, the optimum aromatic content was 86.4 % at 450 °C with a heating rate of 104 °C/s. In the meantime, 3Nb/ZSM-5 presented good stability and recyclability in the fast pyrolysis of corncob, and over 75 % aromatics was achieved even after 3 cycles. Kinetical study revealed that the E a value for corncob pyrolysis could be lowered to ∼ 250 kJ/mol with conversion rate range of 0.4–0.7. • NbO x modification significantly enhanced L-acid sites and regulated pore structure. • Aromatic content achieved 86.4 % at 450 °C for 3Nb/ZSM-5 catalyzed pyrolysis. • Synergistic effect between acid site and pore structure favored aromatics formation. • Simultaneous decomposition of various components resulted in the high E a at low α. [ABSTRACT FROM AUTHOR]

Co-catalytic fast pyrolysis of torrefaction deoxygenated pine wood (PW) and high-density polyethylene (HDPE) in dual-catalyst (metal oxidize and zeolite) system is an effective technology to produce renewable bio-aromatics. In this work, the torrefaction deoxygenation pretreatment (TDP) was carried out to remove oxygen element from PW prior to catalytic fast pyrolysis (CFP). 56.90 % oxygen could be removed at TDP temperature of 300 °C, releasing in the oxygen carrier of CO 2 , CO, H 2 O, alcohols, acids, phenols, etc. Then, the synergistic effect between the metal oxide and the HZSM-5 in dual-catalyst system was also investigated. Among these metal oxides (Al 2 O 3 , MgO, CaO, ZnO, and Fe 2 O 3) and hierarchical HZSM-5, the dual-catalyst of CaO and hierarchical HZSM-5 (treated by 0.2 M NaOH) was the optimal combination. The layout mode between feedstock and dual catalyst was also optimized. The highest yield of aromatics was produced in layout Mode 8, where the CaO was mixed with torrefied PW, but the hierarchical HZSM-5 and HDPE were laid in separated layers. The mixing of CaO and torrefied PW promoted the conversion of the macromolecular oxygenates into micromolecular oxygenates. Then, these small-molecular oxygenates could enter the hierarchical channel of HZSM-5, being converted into aromatics by undergoing the Diels-Alder reaction. [Display omitted] • A systematic approach on the DC-CFP of torrefied PW and HDPE was employed to produce bio-aromatics. • Torrefaction deoxygenation mechanism of pine wood was established. • Oxygen element was released in the oxygen carrier of CO 2 , CO, H 2 O, alcohols, acids, phenols, etc. • The dual-catalyst of CaO and HZ-0.2 was the optimal combination to improve the yield of aromatics. • The synergistic effect between the CaO and HZSM-5 in dual-catalyst system was also investigated. [ABSTRACT FROM AUTHOR]

Catalytic fast pyrolysis (CFP) is an advanced controlled process of biomass thermal decomposition designed to produce high volumes of ready-to-use transportation biofuels or to provide improved quality bio-oil for subsequent refining or upgrading. The present work is the second part of a thorough review on the CFP of lignocellulosic biomass, emphasizing on the exploitation of agricultural residues and dedicated energy crops. Due to the increased interest on the production of high energy density transportation biofuels, such as green gasoline, green jet fuel and green Diesel, CFP has been studied intensely during the last years, using various biomass feedstocks in both in-situ and ex-situ catalytic studies. The scope of the present review is to illustrate and critically discuss the known science and the latest research outcomes of the CFP of agricultural residues and herbaceous or woody dedicated energy crops as it has been tested experimentally over the wide spectrum of available catalysts in the groups of zeolites, mesoporous catalysts, metal oxides, inorganic salts and carbon-based materials. The selection of the appropriate catalyst has a paramount effect on the features of the produced bio-oil, such as composition and properties of the obtained liquid end-product of the CFP process. This is because it influences the overall chemistry/pathways of the CFP process through the selective promotion of certain dehydration, decarboxylation, decarbonylation, hydrodeoxygenation, catalytic cracking and condensation (ketonization and Aldol condensation) reactions, and also, determines the stability and quality of the obtained bio-oil by decreasing its oxygen content and by improving its final properties for use as a fuel or for subsequent further upgrading. As it is discussed in this review, many existing catalysts are able to greatly enhance bio-oil quality by promoting the production of useful aromatic hydrocarbons, phenolics or alkanes. However, further research is needed towards the optimization of the catalytic performances in terms of activity, product selectivity and resistivity against deactivation. • The composition/quality of the obtained CFP bio-oil depends on the catalyst used. • ZSM-5 and HZSM-5 are the most effective zeolites for the production of aromatics. • Meso-MFI catalysts are promising mesoporous materials for the yield of aromatics. • CaO and MgO oxides exhibit promising CFP performance and easier regeneration. • Transportation biofuels are attainable via second-stage uprgading of CFP bio-oil. [ABSTRACT FROM AUTHOR]

The integration of Torrefaction Deoxygenation Pretreatment (TDP) and Catalytic Fast Pyrolysis (CFP) with dual catalysts was employed to improve the yield of bio-aromatics (BTX) derived from Miscanthus. Results showed that the TDP could effectively remove the oxygen content up to 38.16% at 280 °C. This resulted in a remarkable reduction of undesired oxygenate compounds in the pyrolysis oil. With ZSM-5 catalyst, the dominant components in pyrolysis oil became aromatic hydrocarbons (up to 66.29%) instead of oxygenates. The selectivity of bio-BTX increased with the increase of torrefaction temperature up to 56.63%. For the pyrolysis process, the highest yield (37.54%) and selectivity (56.63%) of bio-BTX were obtained at 600 °C. Compared with ZSM-5, the addition of CaO and MoO 3 promoted bio-BTX yield due to the enhanced deoxygenation and olefins aromatization. The integrated TDP and CFP with ZSM-5 and MoO 3 significantly improved the selectivity of bio-BTX, reaching the highest selectivity of 70.69% and a yield of 51.07%. Combining these two processes can enhance bio-aromatics yields from biomass, thus considerably improving the quality and value of the liquid product. [ABSTRACT FROM AUTHOR]

The management of municipal and industrial organic solid wastes has become one of the most critical environmental problems in modern societies. Nowadays, commonly used management techniques are incineration, composting, and landfilling, with the former one being the most common for hazardous organic wastes. An alternative eco-friendly method that offers a sustainable and economically viable solution for hazardous wastes management is fast pyrolysis, being one of the most important thermochemical processes in the petrochemical and biomass valorization industry. The objective of this work was to study the application of fast pyrolysis for the valorization of three types of wastes, i.e., petroleum-based sludges and sediments, residual paints left on used/scrap metal packaging, and creosote-treated wood waste, towards high-added-value fuels, chemicals, and (bio)char. Fast pyrolysis experiments were performed on a lab-scale fixed-bed reactor for the determination of product yields, i.e., pyrolysis (bio)oil, gases, and solids (char). In addition, the composition of (bio)oil was also determined by Py/GC-MS tests. The thermal pyrolysis oil from the petroleum sludge was only 15.8 wt.% due to the remarkably high content of ash (74 wt.%) of this type of waste, in contrast to the treated wood and the residual paints (also containing 30 wt.% inorganics), which provided 46.9 wt.% and 35 wt.% pyrolysis oil, respectively. The gaseous products ranged from ~7.9 wt.% (sludge) to 14.7 (wood) and 19.2 wt.% (paints), while the respective solids (ash, char, reaction coke) values were 75.1, 35, and 36.9 wt.%. The thermal (non-catalytic) pyrolysis of residual paint contained relatively high concentrations of short acrylic aliphatic ester (i.e., n-butyl methacrylate), being valuable monomers in the polymer industry. The use of an acidic zeolitic catalyst (ZSM-5) for the in situ upgrading of the pyrolysis vapors induced changes on the product yields (decreased oil due to cracking reactions and increased gases and char/coke), but mostly on the pyrolysis oil composition. The main effect of the ZSM-5 zeolite catalyst was that, for all three organic wastes, the catalytic pyrolysis oils were enriched in the value-added mono-aromatics (BTX), especially in the case of the treated wood waste and residual paints. The non-condensable gases were mostly consisting of CO, CO2, and different amounts of C1–C4 hydrocarbons, depending on initial feed and use or not of the catalyst that increased the production of ethylene and propylene. [ABSTRACT FROM AUTHOR]

Feedstock attributes of lignocellulosic biomass, such as particle size, compositional makeup, and moisture content, can vary substantially even within pre‐processed materials and have a significant effect on conversion in fast pyrolysis‐based processes. However, the economic impacts of these attributes are not well understood. To address this, biomass deconstruction phenomena captured with a versatile particle‐scale simulation were linked to techno‐economic impacts via reduced‐order models. Parametric analysis of the particle‐scale model, which was validated using literature data, was used in combination with multiple linear regression models to develop correlations between feedstock attributes and yields of pyrolysis oil, gas, and char. Yields were then correlated with the minimum fuel selling price (MFSP) using a techno‐economic model, bridging the gap between physics‐based biomass conversion simulations and predictions of MFSP for a catalytic fast‐pyrolysis process. Empirical correlations derived from the literature regarding the impact of mineral matter (ash) on oil yield were also considered. The model correlations deployed in the integrated framework capture the impacts of variation in feedstock attributes on the MFSP. Variations in ash were shown to have the biggest impact, varying MFSP by −13%/+22% due to catalytic effects and lower relative amounts of convertible lignocellulosic material. It was also found that, if ash can be controlled to low levels, the increased extractives in forest residues can help compensate for some yield losses associated with increased ash. Other inputs considered (particle size, moisture content, and reactor temperature) had relatively negligible effects on process economics within the ranges analyzed considering particle‐scale effects alone. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Catalytic fast pyrolysis of lignin is easy to cause agglomeration and coking, resulting in low-yield aromatic hydrocarbons. Catalytic pyrolysis of modified lignin combined with metal-modified HZSM-5 was proposed to enhance the aromatic yield. The experiment results showed that chemical modification with Ca(OH)2 not only inhibited the agglomeration behavior of lignin but also increased the yield of light phenolic compounds. Moreover, Ca2+-loaded lignin combined with metal-modified HZSM-5 was conducive to the formation of aromatics. The total yield of aromatics from the catalytic fast pyrolysis of Ca2+-loaded lignin over Zn/HZSM-5 was improved from 31.1 to 46.1 mg/g. The mechanism insight showed that Ca2+ modification realized the chemical combination between Ca2+ and the functional groups which are responsible for the agglomeration of lignin, and then the introduction of the Zn species suppressed the hydrogen transfer reaction and enhanced the dehydrogenation pathway, resulting in the increase of aromatic yield.

Fast pyrolysis is a controlled process of biomass thermal decomposition designed to yield high volumes of liquid bio-oil, which can subsequently be upgraded into high energy density transportation biofuels such as green gasoline, green jet fuel and green Diesel. The quality of bio-oil and the efficiency of the overall biomass - to - biofuel process can be enhanced significantly by assisting the fast pyrolysis process with an appropriate catalyst. Catalytic fast pyrolysis (CFP) intends the improvement of specific bio-oil properties like thermal stability, heating value and acidity and the selective production of valuable hydrocarbons (benzene, toluene, xylene, ethene, propene) or biofuels as end products. The present work is the first communication of a thorough two-part review on the CFP of lignocellulosic biomass emphasizing on the exploitation of agricultural residues and dedicated energy crops. It presents the main types of these feedstocks in Europe and USA, their chemical composition and their potential for biofuel production. Then, the mechanism of the fast pyrolysis of biomass is studied, the most appropriate fast pyrolysis reactors are discussed and the basic routes for physical and chemical bio-oil upgrading (dehydration, decarboxylation, decarbonylation, hydrodeoxygenation and condensation) are presented. Finally, the major upgrading technologies of liquid bio-oil through hydrotreating, catalytic cracking, gasification and steam reforming, and the production of renewable hydrocarbon fuels through Fischer-Tropsch synthesis, are reviewed. In the present, first part of the review, the attention focuses on the specific mechanisms and chemical pathways and technologies of fast pyrolysis and bio-oil-upgrading. An understanding of the CFP technology requires also an extensive review on the experimental studies of the pyrolysis of agricultural residues and energy crops and the results obtained over the large number of the different catalytic systems that have been used. Due to the large volume of existing information from the relevant catalytic studies, their review is the subject of a separate publication which forms the second part sequence of the present work. The novelty of this two-part review lies both on the specific attention on the feedstocks of agricultural residues and dedicated energy crops and on the large volume of relative updated information collected, presented, and critically discussed. • In the EU about 131 × 106 tons/year of residues are available for biofuel production. • Green Diesel derived from agricultural residues reduce GHG emissions by 77–176%. • Bio-oil upgrading occurs by dehydration, deoxygenation and condensation reactions. • A catalyst can promote specific chemical pathways to tailor up the bio-oil quality. • Production of biofuels occurs by hydrotreating, catalytic cracking or FT synthesis. [ABSTRACT FROM AUTHOR]

Summary: Catalytic effects in fast pyrolysis of low‐rank coal and coal tar conversion were investigated in a two‐stage fixed‐bed reactor over HZSM‐5 zeolite and Mg/HZSM‐5. Mg/HZSM‐5 caused the lower total tar yield and the higher non‐condensable gas yield but the fraction of light tar (boiling point below 360°C) increased to allow a slightly higher total yield of light tar. It also exhibited good catalytic activity and increased the species of light tar than HZSM‐5 zeolite. The light tar fraction was increased from 45 to 74.6 wt% than without catalyst (66%) at the pyrolysis temperature of 600°C. Ex‐situ catalytic fast pyrolysis over Mg/HZSM‐5 also lowered the contents of element N and S in the resulting coal tars by 29% and 15% respectively. The corresponding increase in the content of element H and molar ratio of H to C of the resulting coal tars was reported as 17% and 13% respectively. The addition of Mg into HZSM‐5 increased the ability of the catalyst for inhibiting coke deposition. [ABSTRACT FROM AUTHOR]

[Display omitted] • High bio-oil yield of low O content by cascade biomass catalytic fast pyrolysis (CFM). • Acid ZrO 2 /ZSM-5-attapulgite catalyzes CFP; base K-(USY-attapulgite) further upgrades. • Micro-spectroscopy to study deactivation modes and reversibility upon regeneration. • Coke in ZrO 2 /ZSM-5-attapulgite causes acid site poisoning. • K-(USY-attapulgite) deactivated irreversibly, damaging structure and basicity. The modes of deactivation -and the extent to which their properties can be restored- of two catalyst bodies used in cascade for bio-oil synthesis have been studied. These catalysts include a solid acid granulate (namely ZrO 2 /desilicated zeolite ZSM-5/attapulgite clay) employed in ex-situ catalytic fast pyrolysis of biomass, and a base extrudate (K-exchanged zeolite USY/attapulgite clay) for the subsequent bio-oil upgrading. Post-mortem analyses of both catalyst bodies with Raman spectroscopy and confocal fluorescence microscopy revealed the presence of highly poly-aromatic coke distributed in an egg-shell manner. Deactivation due to coke adsorption onto acid sites affected the zeolite ZSM-5-based catalyst, while for the base catalyst it is structural integrity loss, resulting from KOH-mediated zeolite framework collapse, the main deactivating factor. A hydrothermal regeneration process reversed the detrimental effects of coke in the acid catalyst, largely recovering catalyst acidity (∼80%) and textural properties (∼90%), but worsened the structural damage suffered by the base catalyst. [ABSTRACT FROM AUTHOR]

Design of highly active catalysts plays a critical role in catalytic fast pyrolysis (CFP) of lignocellulosic biomass. Advanced catalysts can improve the deoxygenation rate of pyrolysis vapors and boost the production of fuel precursors. Zeolites are suitable frameworks for catalyzing pyrolysis vapors into species of transportation fuel value. However, their nano-sized structure limits the diffusion of reactants into pores and over active sites. Consequently, the aggregation of large molecules outside micropores leads to a massive coke formation, blocking pore channels, and thus, preventing the accessibility to acid sites. This could cause quick deactivation and instability of the catalyst, necessitating frequent catalyst regeneration and replenishment. Hierarchical micro/mesopore-structured zeolites are promising candidates to cope with the mentioned challenges. In addition to their adjusted pore structure and increased accessibility of acid sites, the formation of mesoporosity in zeolites provides an adequate room for the deposition of additional active phases such as metal nanoparticles, further boosting the catalytic activity. Different strategies used for preparing hierarchical zeolites can tremendously alter their attributes, and consequently affect product selectivity during CFP of biomass. Focusing on the precursors of transportation fuels (i.e., aromatic hydrocarbons and olefins), the present paper critically reviews the impacts of methods used for synthesizing hierarchical zeolite, on CFP of bio-based feedstocks. Moreover, the role of metal addition to hierarchical zeolites in biomass catalytic pyrolysis is also discussed briefly. Among the different synthesis techniques, desilication treatment using alkaline solutions is the most promising owing to its simplicity, high productivity, and scalability. In terms of product selectivity, the addition of Ga species to hierarchical zeolites can increase aromatic hydrocarbons while Ce incorporation can increase the yield of valuable oxygenates such as furan. Despite the advantages of mono-metallic hierarchical zeolites in producing cherished chemicals, future studies should scrutinize the influence of bi-metallic hierarchical zeolites in bio-based CFP processes.

A techno-economic analysis of production of bio-oil from catalytic pyrolysis of olive mill wastewater sludge has been performed with two different cooling schemes. The two configurations differ in the manner how the bio-oil vapors are quenched. In scheme-1, a vapor compression refrigeration machine is utilized for condensation of bio-oil vapors while in scheme-2, the vapor compression refrigeration machine is replaced by absorption refrigeration machine. The two schemes are modelled in Aspen Plus which provides mass and energy balances. For techno-economic analysis, Aspen process economic analyzer is employed. The model is first validated against experimental data from lab scale and then upscaled to an industrial scale of 100 tonnes/day wet biomass (93 tonnes/day dry biomass). Results show that the model with absorption refrigeration machine (scheme-2) has a slightly better process efficiency and a lower MFSP compared to the model with compression refrigeration machine (scheme-1). Total anticipated capital investment expenses for scheme-1 and scheme-2, comprising plant fixed capital investment (FCI), start-up, working capital, and interest, are expected to be €22.1 M and €17.5 M, respectively. The equipment costs are based on first quarter of 2021 and the economic life of the project is 20 years. Monte Carlo sensitivity analyses showed that the bio-oil MFSP is most vulnerable to discounted cash flow, income tax and bio-oil yield. The production cost of bio-oil varies between €2.16/GGE and €6.19/GGE for scheme-1 and €1.78/GGE and €5.01/GGE for scheme-2 when cost parameters are varied within an industrially relevant range. The findings support the viability of producing bio-oil by catalytic fast pyrolysis on a commercial scale.

Hierarchical ZSM‐5 zeolites have been successfully synthesized via an introduction of pre‐formed ZSM‐5 precursors and glucose‐assisted method. The influence of the amounts of glucose on the zeolite's characteristics of crystallinity, morphology, pore, and acidity of the HZSM‐5 zeolites were studied detailedly. The synthesized material showed a high mesoporous surface area (164.4–182.7 m2/g) and volume (0.14–0.15 m3/g), while the total acidity amount decreased slightly and Brønsted acidity amount increased. Amongst hierarchical ZSM‐5 zeolites samples, the highest aromatic yield of 43.3 % was obtained, more than the yields of the traditional ZSM‐5 (36.3 %). The increase of mesoporousity is the main reason for the increasing of aromatics yield and reducing of the amount of coke. [ABSTRACT FROM AUTHOR]

While biomass-derived carbohydrates have been predominant substrates for biological production of renewable fuels, chemicals, and materials, organic waste streams are growing in prominence as potential alternative feedstocks to improve the sustainability of manufacturing processes. Catalytic fast pyrolysis (CFP) is a promising approach to generate biofuels from lignocellulosic biomass, but it generates a complex, carbon-rich, and toxic wastewater stream that is challenging to process catalytically but could be biologically upgraded to valuable co-products. In this work, we implemented modular, heterologous catabolic pathways in the Pseudomonas putida KT2440-derived EM42 strain along with the overexpression of native toxicity tolerance machinery to enable utilization of 89% (w/w) of carbon in CFP wastewater. The dmp monooxygenase and meta -cleavage pathway from Pseudomonas putida CF600 were constitutively expressed to enable utilization of phenol, cresols, 2- and 3-ethyl phenol, and methyl catechols, and the native chaperones clpB , groES, and groEL were overexpressed to improve toxicity tolerance to diverse aromatic substrates. Next, heterologous furfural and acetone utilization pathways were incorporated, and a native alcohol dehydrogenase was overexpressed to improve methanol utilization, generating reducing equivalents. All pathways (encoded by genes totaling ~30 kilobases of DNA) were combined into a single strain that can catabolize a mock CFP wastewater stream as a sole carbon source. Further engineering enabled conversion of all aromatic compounds in the mock wastewater stream to (methyl)muconates with a ~90% (mol/mol) yield. Biological upgrading of CFP wastewater as outlined in this work provides a roadmap for future applications in valorizing other heterogeneous waste streams. • P. putida is engineered to consume alkylphenols, furfural, and acetone. • meta -cleavage pathway from P. putida CF600 enabled 2- and 3-ethylphenol catabolism. • Engineered P. putida can utilize 89% (w/w) of carbon in CFP wastewater. • Engineered P. putida converts mock wastewater into (methyl)muconates. [ABSTRACT FROM AUTHOR]

In this study, magnetic solid acid Fe3O4/C–SO3H600 was synthesized and applied in catalytic fast pyrolysis of cellulose for the selective production of levoglucosenone (LGO). The catalytic pyrolysis of cellulose could not only reduce the reaction-required temperature and promote the LGO production, but also could be reused for recycling in an economical and practical approach. Under the experimental conditions that the ratio of catalyst to cellulose was 1:1 and the pyrolysis temperature was 300 °C, the yield of LGO reached 20 wt%. This research also explored the mechanism of cellulosic pyrolysis to produce LGO, indicating that LGO could be produced via further dehydration of levoglucosan. [ABSTRACT FROM AUTHOR]

The preparation of valuable chemicals by catalytic fast pyrolysis (CFP) is a promising and environmentally-friendly approach for the selective upgrading of waste cassava residue (CR). This work systematically investigated the conversion mechanism and kinetic characteristics of CR pyrolysis over Ga-modified hollow ZSM-5, for the purpose of enhancing aromatics production. The hollow configuration significantly regulated the structural characteristics of ZSM-5, thus facilitating the diffusion, deoxygenation, and aromatization of pyrolysis intermediates. The incorporation of Ga species and generated Brønsted acid sites remarkably accelerated the reaction rate and suppressed the carbonization at high temperatures, through enhancing the end scission of starch and cellulose components. With the aid of 5Ga/ZSM-H, the relative content of aromatics achieved 95.4% at 700 °C, and still maintained over 92.5% even after 5 cycles. The ring-opening and retro-aldol degradation were identified as crucial steps for the production of ketones and aldehydes separately, which were further transformed into hydrocarbon pools by deoxygenation and subsequently converted into aromatics via Diels-Alder reaction. Kinetic analysis demonstrated that the use of 5Ga/ZSM-H lowered the average activation energy of CR pyrolysis by 14.8%, particularly for the initial pyrolysis stage. Moreover, the plausible mechanism for aromatics formation from Ga-modified hollow ZSM-5 catalyzed CR pyrolysis was proposed. [Display omitted] • The hollow configuration effectively improved the mass transfer of intermediates. • 5Ga/ZSM-H gave aromatics content of 95.4% and exhibited good recyclability. • Ga species facilitated the CR decomposition via activating connection bonds. • 5Ga/ZSM-H remarkably lowered the activated energy at the initial stage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fast pyrolysis of CNS was systematically researched in a bubbling fluidized bed reactor. • Bio-oil from CNS contained a high amount of cardanol monoene and had a high HHV. • Calcined dolomite favored deoxygenation and formation of aromatics and syngas. • Dolomite showed higher CO 2 capture ability at a temperature of 550 °C than at 475 °C. • The dual role of dolomite as catalyst and sorbent in fast pyrolysis was elucidated. A rigorous investigation of characteristic parameters (i.e., pyrolysis temperature, fluidization velocity, and sample particle size) in the fast pyrolysis of cashew nut shells using a bubbling fluidized bed reactor was conducted. The highest liquid yield of 47.87 wt% was obtained for the non-catalytic pyrolysis of cashew nut shells under the following conditions: a temperature of 475 °C, a fluidization velocity of 2.5 times the minimum velocity, and a particle size ranging from 0.45 to 0.71 mm. It was found that the main component of the oil phase was cardanol monoene, and calcined dolomite promoted dehydration, decarboxylation, cracking, and the production of aromatic hydrocarbons and syngas (H 2 and CO). In catalytic pyrolysis with the first-time use of dolomite at 550 °C, the oil phase with the highest heating value of 37.17 MJ/kg was produced, promising as a potential drop-in biofuel. In addition, the carbon capture of dolomite was investigated by analyzing its crystallographic structure, CO 2 desorption behavior, coke oxidation, and changes in elemental content. Accordingly, the catalytic pyrolysis at higher temperatures led to a stronger carbon capture in dolomite. This research has great practical significance in that dolomite is used as a catalyst to improve the quality of pyrolysis bio-oil and as a carbon capture sorbent to mitigate carbon emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovatively utilizing DES synthesized from choline chloride and lactic acid for biomass pretreatment and co-pyrolysis. • Highest removal rate of lignin from biomass achieved after pretreatment reaches 82.37%. • ZSM-5 catalytic pyrolysis increases hydrocarbons by 23.23%, reaching 54.53%. • Significant reduction in acids and carbonyls content observed after pretreatment. The primary objective of this study is to explore the application of a deep eutectic solvent, synthesized from lactic acid and choline chloride, in combination with a pre-treatment involving ZSM-5 catalytic fast pyrolysis, aimed at upgrading the quality of bio-oil. Characterization results demonstrate a reduction in lignin content post-treatment, alongside a significant decrease in carboxyls and carbonyls, leading to an increase in the C/O ratio and noticeable enhancement in crystallinity. During catalytic fast pyrolysis experiments, the pre-treatment facilitates the production of oil fractions, achieving yields of 54.53% for total hydrocarbons and 39.99% for aromatics hydrocarbons under optimized conditions. These findings validate the positive influence of the deep eutectic solvent pre-treatment combined with ZSM-5 catalytic fast pyrolysis on the efficient production of bio-oil and high-value chemical derivatives.. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis of biomass is regarded as a promising method for preparing value-added products. However, the main factors limiting the development of the process at present are the low yield of value-added products and poor selectivity, especially for rapid catalyst deactivation due to coke deposition. The present study focuses on the catalytic pyrolysis of cellulose over metal Co-, Mo-, and Zr-loaded catalysts using a falling fixed bed at 600 °C to evaluate the type of coking of the catalysts as well as the effect of the different metal active sites on the formation of coke deposits. The introduction of Co and Mo metal sites increased the light aromatics yield of ZSM-5 from 128.9 mg/g to 147.2 mg/g and 143.0 mg/g. And the yield of coke deposits decreased from 8.3 to 6.8 and 5.1 wt%. The stability evaluation of the catalyst showed that the deactivation degree of ZSM-5 of the supported metal Co was lower than that of commercial ZSM-5, while the ZSM-5 of the supported metal Mo was rapidly deactivated. The deactivation of the catalysts depended more on the morphology or location of the accumulated coke than on the total amount deposited. The clogging of metal and acidic sites on the surface of the zeolite and the pore channels by the amorphous encapsulating coke was the main cause of catalyst deactivation. The metal Mo active sites promoted dehydrogenation coupling and hydrogen transfer during coke formation, forming a more highly disordered multiring structure, and the metal Co active sites were more capable of decomposing macromolecular compounds, olefins and alkanes, and promoted the formation of graphite-like structural carbon. [Display omitted] • No positive correlation between the degree of catalyst deactivation and coke yield. • Amorphous coated carbon is an important cause of catalyst deactivation. • Mo site promotes dehydrogen coupling and hydrogen transfer during coke formation. • The Co active site promotes the formation of graphite-like structural carbon on coke. [ABSTRACT FROM AUTHOR]

The perpetual market demand for polystyrene results in the gradual accumulation of polystyrene waste, placing a serious burden on the environment. This study proposed a promising method to upcycle polystyrene for styrene-derived monomers through catalytic fast pyrolysis. The metals-incorporated biochar catalysts were synthesized from heavy metals-contaminated manure waste for catalytic fast pyrolysis of polystyrene. The experimental results showed that the bimetallic biochar-derived catalyst containing Zn and Cr (Zn-Cr/C) was more conducive to the liquid production, with an extremely high yield of 88.22 wt%. Monometallic Pb-incorporated biochar catalyst (Pb/C) and bimetallic Zn-Cu co-doped on biochar (Zn-Cu/C) were more favorable for the production of pure styrene, with the mass yield of 61.26 wt% and 60.39 wt%, respectively. Additionally, the study elucidated a deep understanding of the reaction mechanisms involved in the catalytic fast pyrolysis of polystyrene. Simply put, this study introduced a new concept to convert heavy metal-contaminated animal manure into metal-incorporated biochar catalysts for catalytic conversion of polystyrene waste in pure styrene-based monomers. [Display omitted] • A new concept of upcycling polystyrene into pure monomers. • Mono-/bi-/tri-metallic Zn, Cu, Pb, Cr-containing biochar catalysts were prepared. • Bimetallic Zn-Cr/C favored the liquid production, with the high yield of 88.22 wt%. • Pb/C was more favorable for pure styrene production, reaching 61.26 wt%. • Trimetallic Zn-Cu-Pb/C had an obviously negative impact on the liquid production. [ABSTRACT FROM AUTHOR]

Kraft lignin (KL), isolated from black liquor, serves as a significant feedstock for the production of bio-aromatics by catalytic fast pyrolysis (CFP). First, the influence of pH on the chemical structure of KL isolated by the gradient acid precipitation (GAP) was investigated. Then, the dual-catalyst CFP (DC-CFP) was employed to convert KL into light aromatics by using the hierarchical Nb 2 O 5 (Hie-Nb 2 O 5) and the microporous HZSM-5 as catalyst. Results showed that the decrease of pH during GAP promoted the breakage of the ether bond of KL, resulting in lower molecular weight and less content of hydroxyl group in KL. Among the four types of metal oxides (Hie-Nb 2 O 5 , Al 2 O 3 , MgO, and CaO), the synergistic effect of dual-catalyst grouped by Hie-Nb 2 O 5 and HZSM-5 was best for the production of light aromatics. In addition, the maximum production of light aromatics was reached at the pH of 2 and the mass ratio of Hie-Nb 2 O 5 -to-HZSM-5 at 2:2. [Display omitted] • Kraft lignin precipitated from black liquor by the gradient acid precipitation. • The lower precipitation pH was more conducive to the cleavage of ether bonds in lignin. • Dual-catalyst catalytic fast pyrolysis was developed for production of bio-aromatics. • Synergistic effect between the Nb 2 O 5 and HZSM-5 was observed. • The mass ratio of Nb 2 O 5 and HZSM-5 had influence remarkably on bio-aromatics yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ten lignocellulosic biomasses including forest/agricultural residues were pyrolyzed. • Correlation analysis of 8 biomass properties and 9 pyrolysis products were given. • Noncatalytic bio-oil yield had the highest correlation with holocellulose content. • Hydrocarbons catalyzed by ZSM-5 was closely related to H/C ratio of biomass. • ZSM-5@SBA-15 inhibited the production of PAHs for most biomass sources. Catalytic fast pyrolysis (CFP) is a promising method to convert biomass waste into sustainable bio-oils. However, the relationship gap between biomass characteristics and bio-oil quality has hindered the development of CFP technology. This study investigated the pyrolysis and CFP of ten biomass sources over zeolites, and showed that biomass sources and zeolites played important roles in bio-oil production. For noncatalytic trials, the bio-oil yield was positively related to holocellulose ( R2 = 0.75) and volatiles content ( R2 = 0.62) but negatively to ash content ( R2 = -0.65). The bio-oil quality was dramatically improved after catalyst addition. For CFP over ZSM-5, hydrocarbons selectivity of bio-oils was increased by 1.6∼79.3 times, which was closely related to H/C ratio ( R2 = 0.79). For ZSM-5@SBA-15 trials, the dependency of hydrocarbons selectivity on biomass characteristics was less clear than that in ZSM-5 counterparts, although undesirable PAHs were inhibited for most biomass sources. This study demonstrated the influence mechanism of biomass characteristics on bio-oil compositions. [ABSTRACT FROM AUTHOR]

Lignin, isolated from black liquor, is an important feedstock to produce bio-aromatics through catalytic fast pyrolysis. First, the variation in chemical structure among the Kraft lignin precipitated by the organic acids (acetic acid and citric acid) and the inorganic acids (hydrochloric acid and sulfuric acid) was investigated. Then, a sustainable production approach of light aromatics from Kraft lignin was developed, namely the dual-catalyst catalytic fast pyrolysis (DC-CFP) by using the mesoporous Nb 2 O 5 and microporous HZSM-5 as catalyst. Results showed that the molecular weight of lignin isolated by inorganic acids (1674–1841 g/mol) was much lower than that of lignin isolated by organic acids (2040–2441 g/mol), caused by the fact that inorganic acids promoted the breakage of ether bonds in lignin. In addition, compared with lignin precipitated by the organic acids, the CFP of lignin precipitated by the inorganic acids has a higher yield of light aromatics, especially the lignin precipitated by the hydrochloric acid, reaching 1.39 × 108 a. u./mg. Among the different layout modes of catalyst, Model II (Meso-Nb 2 O 5 blended with lignin, HZSM-5 placed separately from lignin) presented highest yield of light aromatics during DC-CFP of lignin, reaching 1.78 × 108 a. u./mg. [Display omitted] • Kraft lignin precipitated from black liquor by the organic and inorganic acids. • Inorganic acids promoted the cleavage of ether bonds in lignin. • Dual-catalyst catalytic fast pyrolysis was developed for production of bio-aromatics. • Synergistic effect between the Nb 2 O 5 and HZSM-5 was observed. • Layout mode of catalyst and lignin had influence remarkably on bio-aromatics yield. [ABSTRACT FROM AUTHOR]