Fast microwave-assisted catalytic co-pyrolysis of corn stover and scum for bio-oil production with CaO and HZSM-5 as the catalyst

Characteristic analysis of bio-oil from penicillin fermentation residue by catalytic pyrolysis

The hazardous waste penicillin fermentation residue (PR) is a huge hazard to the environment. The bio-oil produced by the pyrolysis of the penicillin fermentation residue has the potential to become a biofuel in the future. This paper studied the pyrolysis characteristics of PR at 400°C ∼700°C. According to the weight loss and weight loss rate of PR, the whole process of pyrolysis can be divided into three stages for analysis: dehydration and volatilization, initial pyrolysis, and pyrolytic char formation. The experimental results showed that the yield of the liquid phase is the highest (33.11%) at 600°C. GC-MS analysis results showed that high temperature is beneficial to reduce the generation of oxygenated hydrocarbons (73%∼31%) and the yield of nitrogenous compounds gradually increased (19%∼43%); the yield of hydrocarbons was low in 400°C∼600°C pyrolysis (2%∼5%) but significantly increased around 700°C (22%). In the temperature range of 400°C to 700°C, the proportion of C5-C13 in bio-oil gradually increased (26%-64%), and the proportion of C14-C22 gradually decreased (47%-16%). The catalyst can increase the proportion of hydrocarbons in the bio-oil component. And the Fe₂O₃/HZSM-5 mixed catalyst has a significant reduction effect on oxygen-containing hydrocarbons and nitrogen-containing compounds.

Lignin and spent bleaching clay into mono-aromatic hydrocarbons by a cascade dual catalytic pyrolysis system: Critical role of spent bleaching clay

In the present study, a cascade dual catalytic system was used for the co-pyrolysis of lignin with spent bleaching clay (SBC) to efficiently produce mono-aromatic hydrocarbon (MAHs). The cascade dual catalytic system is composed of calcined SBC (CSBC) and HZSM-5. In this system, SBC not only acts as a hydrogen donor and catalyst in the co-pyrolysis process, but is also used as a primary catalyst in the cascade dual catalytic system after recycling the pyrolysis residues. The effects of different influencing factors (i.e., temperature, CSBC-to-HZSM-5 ratio, and raw materials-to-catalyst ratio) on the system were explored. It was observed that, when the temperature was 550 °C, the CSBC-to-HZSM-5 ratio was 1:1, and when the raw materials-to-catalyst ratio was 1:2, the highest bio-oil yield was 21.35 wt%. The relative MAHs content in bio-oil was 73.34 %, whereas the relative polycyclic aromatic hydrocarbons (PAHs) content was 23.01 %. Meanwhile, the introduction of CSBC inhibited the generation of graphite-like coke as indicated by HZSM-5. This study realizes the full resource utilization of spent bleaching clay and reveals the environmental hazards caused by spent bleaching clay and lignin waste.

Pyrolysis of vegetable oil soapstock in fluidized bed: Characteristics of thermal decomposition and analysis of pyrolysis products

This study investigated the effect of temperature on pyrolysis of soapstock in a fluidized bed reactor, and the characterization of soapstock chars (SCs) and pyrolysis oils (POs) were analyzed. TGA, TG-FTIR, TG-MS, and Py-GCMS were employed to investigate characteristics of SS pyrolysis. Experimental results indicated that the yield of SC decreased with increasing temperature. Pyrolysis oil (PO) yield reached the maximum of 21.05 wt% at 600 °C and the yield of non-condensable gas varied with temperatures. The content of carbon, hydrogen and nitrogen distributed in the SC decreased with the increasing temperature, and sulfur tended to be retained in SC during pyrolysis with the distribution ratio of 0.55-0.62. Ketones, alcohols and hydrocarbons were the dominate substances in PO, and higher temperature promoted the production of short-chain alkanes and the conversion of alkenes to benzene derivatives. SS pyrolysis can be divided into three stages. Stage I was mainly the evaporation of free water and light organics in the raw material. Decomposition and conversion of organics mainly occurred at stage II. Stage III was the decomposition of CaCO₃ and secondary cracking of residual organics. Ca²⁺ delayed the pyrolysis reaction of fatty acids and promoted decarboxylation which was the main deoxygenation pathway, and alkene production. This study provided a theoretical basis for the application of soapstock thermochemical treatment. It is of great significance for the quality improvement of PO and pollution control for pyrolysis processes.

Synthesis of CaO from waste shells for microwave-assisted catalytic pyrolysis of waste cooking oil to produce aromatic-rich bio-oil

Energy shortage and environmental pollution have attracted long-term attention. In this study, CaO were prepared from waste eggshell (EGC), preserved egg shell (PEC), clam shell (CLC) and crab shell (CRC), which were then compared with commercial CaO (CMC) to catalyze microwave-assisted pyrolysis of waste cooking oil (WCO) for enrichment of aromatics in bio-oil. The characterization results indicated that EGC and CLC contained 95.54% and 95.61% CaO respectively, which were higher than that of CMC (95.11%), and the pore properties of EGC were the best. In addition, the effects of CaO type and catalytic mode on pyrolysis were studied. In CaO catalytic pyrolysis, CMC and CLC in-situ catalysis produced more aromatics than ex-situ catalysis, and PEC and CRC were more conducive to aromatics formation in ex-situ condition. EGC was conducive to produce benzene, toluene and xylene (BTX) both in in-situ (19.04%) and ex-situ (20.76%) catalytic pyrolysis. In CaO/HZSM-5 catalysis, the optimal dual catalytic mode for generating monocyclic aromatic hydrocarbons (MAHs) was Mode A (CaO separated from HZSM-5 for ex-situ catalysis), and EGC/HZSM-5 performed well in benzene, toluene and xylene (BTX) production.

Catalytic pyrolysis of lignocellulosic biomass for bio-oil production: A review

Catalytic pyrolysis has been widely explored for bio-oil production from lignocellulosic biomass owing to its high feasibility and large-scale production potential. The aim of this review was to summarize recent findings on bio-oil production through catalytic pyrolysis using lignocellulosic biomass as feedstock. Lignocellulosic biomass, structural components and fundamentals of biomass catalytic pyrolysis were explored and summarized. The current status of bio-oil yield and quality from catalytic fast pyrolysis was reviewed and presented in the current review. The potential effects of pyrolysis process parameters, including catalysts, pyrolysis conditions, reactor types and reaction modes on bio-oil production are also presented. Techno-economic analysis of full-scale commercialization of bio-oil production through the catalytic pyrolysis pathway was reviewed. Further, limitations associated with current practices and future prospects of catalytic pyrolysis for production of high-quality bio-oils were summarized. This review summarizes the process of bio-oil production from catalytic pyrolysis and provides a general scientific reference for further studies.

Waste surgical masks to fuels via thermochemical co-processing with waste motor oil and biomass

In this work, the co-processing of waste surgical masks, waste motor oil, and biomass was investigated to reduce the environmental impacts of the increasing medical-derived plastic pollution as well as to elucidate its effect on the production of chemicals . The results showed high yields towards an oily product with an interesting hydrocarbon content in the diesel range. Furthermore, although the initial waste motor oil had a high sulfur content, the oily products showed a low sulfur content, that was logically distributed in the solid and gas phases. In addition, all oily products presented HHVs ​​higher than 44 MJ/Kg, with cetane indices, densities, and viscosities lower than those of petroleum-derived diesel. This work could impact on the management of waste surgical masks and the joint recovery of everyday waste towards high value-added products.

Petroleum oil and products recovery from oily sludge: Characterization and analysis of pyrolysis products

Oily sludge (OS) has attracted special interest because of its hazardous nature and high potential as an energy resource. This study investigated the oil recovery from OS by thermal cracking and catalytic pyrolysis. The oil yield increased when the temperature exceeded 450 °C and reached a maximum (76.84 wt%) at 750 °C. Catalysts significantly improved the quality of oil produced during catalytic pyrolysis. Aromatic hydrocarbons were dominant (10.01-52.69%) in pyrolysis oil (PO) from OS catalytic pyrolysis, and the catalysts significantly reduced the presence of oxygen heterocycles. In addition, KOH and CaO reduced the I_D (D-band peak intensity)/I_G (G-band peak intensity) of OS char (OC) and increased the degree of graphitization. Owing to its higher iodine adsorption value and methylene blue (MB) adsorption value, OC exhibits potential as an adsorbent. The environmental assessment and potential applications of OC, along with possible reaction mechanisms and kinetic characteristics, are also discussed.

Characterization and Use of Char Produced from Pyrolysis of Post-Consumer Mixed Plastic Waste

In this work, the pyrolysis of post-consumer mixed plastic waste (polypropylene (PP), polystyrene (PS) and polyethylene film (PE)) is carried out. The solid product of the pyrolysis is characterized and tested for its use as adsorbent of lead present in aqueous media. The pyrolysis temperature has a great influence on the solid product yield, decreasing when the temperature increases. The highest yield to solid product obtained is from the pyrolysis of film at lower temperature (450 °C), reaching almost 14%. The results of product solid characterization reveal that the carbon, hydrogen and nitrogen content decreases with increasing pyrolysis temperature. Furthermore, both the ash and the volatile content are related to the pyrolysis temperature. The ash content is higher when the pyrolysis temperature is higher, while when the temperature increases, a solid product with lower volatile content is obtained. In respect to specific surface area, a higher pyrolysis temperature improves the properties of the solid product as an adsorbent. The adsorption capacity increases as the pyrolysis temperature increases, with the highest value of 7.91 mg/g for the solid obtained in the pyrolysis at 550 °C. In addition, adsorption capacity increases as the initial concentration of lead rises, reaching a maximum value close to 26 mg/g for an initial concentration of 40 mg/L. The Sips model is the one that best reproduces the experimental results of the adsorption process equilibrium study.

A Review of Bio-Oil Production through Microwave-Assisted Pyrolysis

The issue of sustainability is a growing concern and has led to many environmentally friendly chemical productions through a great intensification of the use of biomass conversion processes. Thermal conversion of biomass is one of the most attractive tools currently used, and pyrolytic treatments represent the most flexible approach to biomass conversion. In this scenario, microwave-assisted pyrolysis could be a solid choice for the production of multi-chemical mixtures known as bio-oils. Bio-oils could represent a promising new source of high-value species ranging from bioactive chemicals to green solvents. In this review, we have summarized the most recent developments regarding bio-oil production through microwave-induced pyrolytic degradation of biomasses.

A review on advanced catalytic co-pyrolysis of biomass and hydrogen-rich feedstock: Insights into synergistic effect, catalyst development and reaction mechanism

The depletion of fossil fuel reserves and the growing demand for alternative energy sources are the main drivers of biomass and carbonaceous waste utilization. Particularly, non-edible lignocellulosic biomass is the most attractive renewable feedstock due to its abundance. Pyrolysis of biomass produces highly oxygenated compounds with oxygen content >35 wt%. The cost-effective elimination of oxygen from the pyrolysis oil is the most challenging task impeding the commercialization of biomass to biofuel processes. The effective hydrogen/carbon ratio in biomass pyrolysis oil is low (0.3), requiring external hydrogen supply to produce hydrocarbon-rich oils. Exploiting hydrogen-rich feedstock particularly, solid waste (plastic, tyre and scum) and other low-cost feedstock (lubricant oil, methane, methanol, and ethanol) offer an eco-friendly solution to upgrade the produced bio-oil. Multi-functional catalysts that are capable of cleaving oxygen, promoting hydrogen transfer and depolymerisation must be developed to produce hydrocarbon-rich oil from biomass. This review compares catalytic co-pyrolysis studies based on zeolites, mesoporous silica and metal oxides. Furthermore, a wide range of catalyst modifications and the role of each feedstock were summarised to give a complete picture of the progress made on biomass co-pyrolysis research and development.

Effective deoxygenation for the production of liquid biofuels via microwave assisted co-pyrolysis of agro residues and waste plastics combined with catalytic upgradation

Rice straw and sugarcane bagasse were co-pyrolyzed with polypropylene and polystyrene using microwaves, and the pyrolysis vapors were catalytically upgraded using HZSM-5 catalyst. The product yields, composition and properties of bio-oil from pyrolysis of individual feedstocks and equal composition mixtures before and after catalytic upgradation were thoroughly investigated. The pyrolysis oil yields from polypropylene (82 wt%) and polystyrene (98 wt%) were high compared to that from rice straw (26 wt%) and bagasse (29 wt%). Catalytic upgradation at weight hourly space velocity of 11 h^-1 resulted in higher selectivity to unsaturated aliphatics and aromatic hydrocarbons. Properties of upgraded bio-oil from biomass-polypropylene mixtures were similar to that of light fuel oil with high calorific value (43 MJ/kg), low viscosity (1 cP), optimum density (0.850 g/cm³) and flash point (70 °C). Oxygen content in catalytically upgraded co-pyrolysis bio-oil was low (<5%) as compared to upgraded pyrolysis bio-oil (14-18%), and pyrolysis bio-oil without upgradation (20-24%).

Catalytic co-pyrolysis behaviors, product characteristics and kinetics of rural solid waste and chlorella vulgaris

Catalytic and non-catalytic co-pyrolysis behaviors, kinetics and products distribution of rural solid waste (RSW) and chlorella vulgaris (CV) were studied by thermogravimetric analysis (TGA) and fixed bed reactor. TGA results showed that co-pyrolysis of RSW and CV presented synergism by decreasing the temperature relating to the first mass loss peak. All the additives reduced residual mass for co-pyrolysis (5.21%, 1.57% and 4.89% for CaO, MgO and HZSM-5). Addition of CaO increased activation energy while HZSM-5 and MgO reduced it. Co-pyrolysis of RSW and CV remarkably reduced carboxylic acids and nitrogenous compounds especially for 1:1 ratio. (30.85% and 25.87%). Catalytic pyrolysis with CaO showed the best results by increasing aliphatic hydrocarbons especially light fraction (5.96%-11.98%), reducing acids (0%-30.85%) and nitrogenous compounds (0.08%-17.26%), causing higher HHV of oil. Overall, catalytic co-pyrolysis of CV and RSW with CaO could obtain bio-oil of higher quality.

Fast microwave-assisted pyrolysis of wastes for biofuels production - A review

Microwave-assisted pyrolysis of waste suffers from the problem that the waste generally has low microwave absorptivity thereby resulting in low heating rate and low pyrolysis temperature. In this case, fast microwave-assisted pyrolysis is proposed and developed to help the pyrolysis of waste. This study describes two methods that can be used to realize fast microwave-assisted pyrolysis of waste: (1) premixed method (wastes are mixed with microwave absorbent) and (2) non-premixed method (wastes are poured onto the heated microwave absorbent bed). Then, biofuels (bio-oil, bio-gas, and bio-char) produced from fast microwave-assisted pyrolysis of wastes are reviewed. The review results show that the yields of bio-oil, bio-gas, and bio-char obtained from fast microwave-assisted pyrolysis of wastes varied significantly in the ranges of 2-96 wt%, 2.4-86.8 wt%, and 0.3-83.2 wt%, respectively. Although the present research focused mainly on the premixed method, non-premixed/continuous fast microwave-assisted pyrolysis is still promising and challenging.

Production of H2-Rich Syngas From Lignocellulosic Biomass Using Microwave-Assisted Pyrolysis Coupled With Activated Carbon Enabled Reforming

This study focuses on the use of a microwave reactor that combines biomass pyrolysis, at mild temperature, with catalytic reforming of the pyrolytic gas, using activated carbon, for generating hydrogen-rich synthesis gas. The traditional pyrolysis of biomass coupled with the reforming of its pyrolytic yields were also conducted using an electrically heated reactor. The bio-oil attained from conventional pyrolysis was higher in comparison to the yield from microwave pyrolysis. The reforming of the pyrolytic gas fraction led to reductions in bio-oil yield to <3.0 wt%, with a simultaneous increase in gaseous yields. An increase in the syngas and H₂ selectivity was discovered with the reforming process such that the use of microwave pyrolysis with activated carbon reforming produced 85 vol% synthesis gas fraction containing 55 vol% H₂ in comparison to the 74 vol% syngas fraction with 30 vol% H₂ obtained without the reforming. Cracking reactions were improved with microwave heating, while deoxidation and dehydrogenation reactions were enhanced by activated carbon, which creates a reduction environment. Consequently, these reactions generated H₂-rich syngas formation. The approach implemented in this study revealed higher H₂, syngas yield and that the overall LHV of products has huge potential in the transformation of biomass into high-value synthesis gas.

Catalytic pyrolysis of biomass wastes over Org-CaO/Nano-ZSM-5 to produce aromatics: Influence of catalyst properties

Catalytic pyrolysis of biomass wastes is a promising way to produce aromatics. Based on the conventional CaO/ZSM-5 system, this study aims to improve the aromatics yields by developing an upgraded system which combined nanosized ZSM-5 with CaO from organic calcium precursors (Org-CaO/NZSM-5). The results showed that the aromatics proportion in bio-oil from pyrolysis of Jatropha de-oiled cake with Org-CaO/NZSM-5 increased to 93%. The corresponding yield of BTX (benzene, toluene and xylene) and naphthalene was around 70% which was almost twice than that with conventional CaO/ZSM-5. Org-CaO showed better thermal cracking ability and deoxygenation with more hydrocarbons intermediates and higher H/C_eff of vapors, contributing to enhanced formation of BTX over NZSM-5. NZSM-5 contained much more mesopores and acid sites on external surface, promoting higher conversion of bulky molecules into naphthalenes. Compared with peanut shell, corncob and bagasse pyrolysis, Jatropha de-oiled cake pyrolysis produced much higher aromatics with Org-CaO/NZSM-5.

Ca-based Catalysts for the Production of High-Quality Bio-Oils from the Catalytic Co-Pyrolysis of Grape Seeds and Waste Tyres

The catalytic co-pyrolysis of grape seeds and waste tyres for the production of high-quality bio-oils was studied in a pilot-scale Auger reactor using different low-cost Ca-based catalysts. All the products of the process (solid, liquid, and gas) were comprehensively analysed. The results demonstrate that this upgrading strategy is suitable for the production of better-quality bio-oils with major potential for use as drop-in fuels. Although very good results were obtained regardless of the nature of the Ca-based catalyst, the best results were achieved using a high-purity CaO obtained from the calcination of natural limestone at 900 °C. Specifically, by adding 20 wt% waste tyres and using a feedstock to CaO mass ratio of 2:1, a practically deoxygenated bio-oil (0.5 wt% of oxygen content) was obtained with a significant heating value of 41.7 MJ/kg, confirming its potential for use in energy applications. The total basicity of the catalyst and the presence of a pure CaO crystalline phase with marginal impurities seem to be key parameters facilitating the prevalence of aromatisation and hydrodeoxygenation routes over the de-acidification and deoxygenation of the vapours through ketonisation and esterification reactions, leading to a highly aromatic biofuel. In addition, owing to the CO2-capture effect inherent to these catalysts, a more environmentally friendly gas product was produced, comprising H2 and CH4 as the main components.

Co-pyrolysis of sugarcane bagasse and polystyrene with ex-situ catalytic bed of metal oxides/HZSM-5 with focus on liquid yield

Catalytic co-pyrolysis of sugarcane bagasse (SCB) and polystyrene (PS) was conducted in a fixed bed reactor over microporous HZSM-5, mesoporous metal oxides (MgO, CaO) and their blends to examine the effect on pyrolytic liquid yields and quality. Though the catalyst addition decreased the liquid yield, improvement in mono-aromatic hydrocarbon yield with the least content of oxygenates was achieved in the catalytic trials. Results revealed that HZSM-5 showed maximum conversion efficiency of acids, furans and phenols acting as hydrocarbon source for aromatic production. Basic MgO, with acidic HZSM-5, was found to conduce better catalytic performance yielding improved oil quality compared to HZSM-5:CaO catalyst. Mass ratio of 1:3 HZSM-5:MgO exhibited most eminent synergistic effect with maximum (56.8 wt%) mono-aromatic hydrocarbon (MAH) yield and lowest (20.8 wt%) poly-aromatic hydrocarbon (PAH) content. Additionally, increased calorific value and density upgradation comparable to standard diesel fuel quality were observed in the presence of dual catalyst layout.

Catalytic co-pyrolysis of sugarcane bagasse and waste high-density polyethylene over faujasite-type zeolite

This study investigated the catalytic co-pyrolysis of sugarcane bagasse (SCB) and waste high-density polyethylene (HDPE) over faujasite-type zeolite derived from electric arc furnace slag (FAU-EAFS) in a fixed-bed reactor. The effects of reaction temperature, catalyst-to-feedstock ratio, and HDPE-to-SCB ratio on product fractional yields and chemical compositions were discussed. The co-pyrolysis of SCB and HDPE over FAU-EAFS increased the liquid yield and enhanced the quality of bio-oil. The maximum bio-oil (68.56 wt%) and hydrocarbon yield (74.55%) with minimum yield of oxygenated compounds (acid = 0.57% and ester = 0.67%) were achieved under the optimum experimental conditions of catalyst-to-feedstock ratio of 1:6, HDPE-to-SCB ratio of 40:60, and temperature of 500 °C. The oil produced by catalytic co-pyrolysis had higher calorific value than the oil produced by the pyrolysis of SCB alone.

Co-pyrolysis of biomass and soapstock in a downdraft reactor using a novel ZSM-5/SiC composite catalyst

A ZSM-5/SiC composite catalyst was synthesized and characterized by Brunauer-Emmett-Teller analysis, X-ray diffraction, and scanning electron microscopy in this study. The composite catalyst had the characteristics of ZSM-5 and SiC, and the surface of SiC grew evenly with a layer of ZSM-5. The effect of the composite catalyst on the product distribution and chemical composition in a co-pyrolysis downdraft system was investigated. In a down system with a catalytic temperature of 450 °C, a feed-to-catalyst ratio of 2:1, and a soybean-soapstock-to-straw ratio of 1:1, the proportions of alkanes, olefins, aromatics, and phenoxy compounds were 6.82%, 4.5%, 73.56% and 11.11%, respectively. The composite catalyst combined the catalytic performance of ZSM-5 and SiC, increasing the proportion of aromatics and decreasing the proportion of oxygen-containing compound in the bio-oil. Moreover, the composite catalyst maintained its activity after reusing several times.

Catalytic pyrolysis of lignin in a cascade dual-catalyst system of modified red mud and HZSM-5 for aromatic hydrocarbon production

Catalytic pyrolysis of lignin over a dual-catalyst system of modified red mud and HZSM-5 was carried out in a bench-scale micro-reactor. Effects of pyrolysis temperature, modified red mud to HZSM-5 ratio, catalysts to lignin ratio on the yield of products and selectivity of aromatic hydrocarbons were investigated. Results indicated that 550 °C was the optimal pyrolysis temperature with the maximal yield of bio-oil (20.16 wt%). At a modified red mud to HZSM-5 ratio of 1:1, the content of monocyclic aromatic hydrocarbons (MAHs) increased to 41.27% whereas that of polycyclic aromatic hydrocarbons (PAHs) decreased to 22.65%. Likewise, at a catalysts to lignin ratio of 2:1, a higher content of MAHs was produced with a decreased content of PAHs. The cascade dual-catalyst system may serve as an efficient approach to disposing lignin and red mud wastes with significant environmental impact. Besides, this study provides a solution for the valorization of lignin-rich resources.

Kraft Lignin Conversion into Energy Carriers under the Action of Electromagnetic Radiation

In this work, it was found that the deposition of iron salts (iron acetate) on kraft lignin at extremely low concentrations of 0.1 wt.% leads to a sharp increase in the absorbing capacity of microwave radiation by kraft lignin at its power of 1 kW and the conversion of kraft lignin to a hydrogen-containing gas with the degree of hydrogen extraction, reaching 90% based on the hydrogen contained in the kraft lignin. It has been established that the deposition of metals (Fe and Ni) on kraft lignin allows one to directionally change the selectivity of the process of its destruction under the influence of microwave radiation, which makes it possible to classify the process as plasmacatalytic. The results obtained make it possible to minimize the amount of catalyst used and propose an efficient way of producing hydrogen from kraft lignin waste.

Improving hydrocarbon yield via catalytic fast co-pyrolysis of biomass and plastic over ceria and HZSM-5: An analytical pyrolyzer analysis

The excessive oxygen content in biomass obstructs the production of high-quality bio-oils. In this work, we developed a tandem catalytic bed (TCB) of CeO₂ and HZSM-5 in an analytical pyrolyzer to enhance the hydrocarbon production from co-pyrolysis of corn stover (CS) and LDPE. Results indicated that CeO₂ could remove oxygen from acids, aldehydes and methoxy phenols, producing a maximum yield of hydrocarbons of 85% and highest selectivity of monocyclic aromatics of 73% in the TCB. The addition of LDPE exhibited a near-complete elimination of oxygenates, leaving hydrocarbons as the overwhelming products. With increasing LDPE proportion, the yield of aliphatics and the selectivity of BTX kept increasing. An optimum H/C_eff of 0.7 was superior to that reported in literature. Mechanisms consisting of deoxygenation, Diels-Alder reactions, hydrocarbon pool and hydrogen transfer reactions were discussed extensively. Our findings provide an efficient method to produce high-quality biofuels from renewable biomass resources.

Synergetic effects during co-pyrolysis of biomass and waste tire: A study on product distribution and reaction kinetics

The synergetic effects during co-pyrolysis of biomass and waste tire (WT) were investigated concerning the product distribution and reaction kinetics. Two biomass feedstocks were separately mixed with WT at different effective hydrogen/carbon ratio (H/C_eff), and analytical co-pyrolysis of mixtures was conducted using pyrolysis gas chromatography/mass spectroscopy at 500 °C. Product distributions were similar between different biomass feedstocks but varied significantly at different H/C_eff values. The percentage of hydrocarbons increased significantly when increasing H/C_eff, and the optimal H/C_eff was determined considering the correspondingly higher yield of polycyclic aromatic hydrocarbons and char residuals at higher percentage of WT. The experimental derivative thermogravimetric curves of mixtures at the optimal H/C_eff were compared with the calculated results based on kinetic analysis of three individual components using the distributed activation energy model. Significant synergetic effects were observed at the initial and final stages of the pyrolysis process.

Co-pyrolysis of microwave-assisted acid pretreated bamboo sawdust and soapstock

Fast microwave-assisted co-pyrolysis of pretreated bamboo sawdust and soapstock was conducted. The pretreatment process was carried out under microwave irradiation. The effects of microwave irradiation temperature, irradiation time, and concentration of hydrochloric acid on product distribution from co-pyrolysis and the relative contents of the major components in bio-oil were investigated. A maximum bio-oil yield of 40.00 wt.% was obtained at 200 °C for 60 min with 0.5 M hydrochloric acid. As pretreatment temperature, reaction time and acid concentration increased, respectively, the relative contents of phenols, diesel fraction (C12 + aliphatics), and other oxygenates decreased. The gasoline fraction (including C5-C12 aliphatics and aromatics) ranged from 55.77% to 73.30% under various pretreatment conditions. Therefore, excessive reaction time and concentration of acid are not beneficial to upgrading bio-oil.

Development and application of a continuous fast microwave pyrolysis system for sewage sludge utilization

A continuous fast microwave-assisted pyrolysis system was designed, fabricated, and tested with sewage sludge. The system is equipped with continuous biomass feeding, mixing of biomass and microwave absorbent, and separated catalyst upgrading. The effect of the sludge pyrolysis temperature (450, 500, 550, and 600 °C) on the products yield, distribution and potentially energy recovery were investigated. The physical, chemical, and energetic properties of the raw sewage sludge and bio-oil, char and gas products obtained were analyzed using elemental analyzer, GC-MS, Micro-GC, SEM and ICP-OES. While the maximum bio-oil yield of 41.39 wt% was obtained at pyrolysis temperature of 550 °C, the optimal pyrolysis temperature for maximum overall energy recovery was 500 °C. The absence of carrier gas in the process may be responsible for the high HHV of gas products. This work could provide technical support for microwave-assisted system scale-up and sewage sludge utilization.

Fast microwave-assisted ex-catalytic co-pyrolysis of bamboo and polypropylene for bio-oil production

The ex-catalytic co-pyrolysis of bamboo and polypropylene (PP) with HZSM-5 was investigated with microwave assistance. The influences of catalytic temperature, feedstock/catalyst ratio, and bamboo/PP ratio on the product yields and chemical components of bio-oil from the co-pyrolysis were studied. When the catalytic temperature, feedstock/catalyst ratio, and bamboo/PP ratio were 250 °C, 1:2, and 2:1, respectively, the bio-oil yield reached its maximum value at 61.62 wt%. The oxygenate proportion compounds decreased with increasing catalyst content. The PP addition improved the proportions of aromatics and naphthenic hydrocarbons. The bio-oil was upgraded significantly from the jet fuel perspective. A synergistic effect also existed between bamboo and PP.

Bio-oil from fast pyrolysis of lignin: Effects of process and upgrading parameters

Effects of process parameters on the yield and chemical profile of bio-oil from fast pyrolysis of lignin and the processes for lignin-derived bio-oil upgrading were reviewed. Various process parameters including pyrolysis temperature, reactor types, lignin characteristics, residence time, and feeding rate were discussed and the optimal parameter conditions for improved bio-oil yield and quality were concluded. In terms of lignin-derived bio-oil upgrading, three routes including pretreatment of lignin, catalytic upgrading, and co-pyrolysis of hydrogen-rich materials have been investigated. Zeolite cracking and hydrodeoxygenation (HDO) treatment are two main methods for catalytic upgrading of lignin-derived bio-oil. Factors affecting zeolite activity and the main zeolite catalytic mechanisms for lignin conversion were analyzed. Noble metal-based catalysts and metal sulfide catalysts are normally used as the HDO catalysts and the conversion mechanisms associated with a series of reactions have been proposed.

The effects of catalysts on the conversion of organic matter and bio-fuel production in the microwave pyrolysis of sludge at different temperatures

Adding catalyst could improve the yields and qualities of bio-gas and bio-oil, and realize the oriented production. Results showed that the catalytic gas-production capacities of CaO were higher than those of Fe₂O₃, and the bio-gas yield at 800°C reached a maximum of 35.1%. Because the polar cracking active sites of CaO reduced the activation energy of the pyrolysis reaction and resulted in high catalytic cracking efficiencies. In addition, the quality of bio-oil produced by CaO was superior to that by Fe₂O₃, although the bio-oil yield of CaO was relatively weak. The light bio-fuel oriented catalytic pyrolysis could be realized when adding different catalysts. At 800°C, CaO was 45% higher than Fe₂O₃ in aspect of H₂ production while Fe₂O₃ was 103% higher than CaO in aspect of CH₄ production. Therefore, CaO was more suitable for H₂ production and Fe₂O₃ was more suitable for CH₄ production.

Pyrolysis of corn stalk biomass briquettes in a scaled-up microwave technology

Pyrolysis of corn stalk biomass briquettes was carried out in a developed microwave (MW) reactor supplied with 2.45GHz frequency using 3kW power generator. MW power and biomass loading were the key parameters investigated in this study. Highest bio-oil, biochar, and gas yield of 19.6%, 41.1%, and 54.0% was achieved at different process condition. In terms of quality, biochar exhibited good heating value (32MJ/kg) than bio-oil (2.47MJ/kg). Bio-oil was also characterised chemically using FTIR and GC-MS method. This work may open new dimension towards development of large-scale MW pyrolysis technology.

A review of catalytic microwave pyrolysis of lignocellulosic biomass for value-added fuel and chemicals

Lignocellulosic biomass is an abundant renewable resource and can be efficiently converted into bio-energy by a bio-refinery. From the various techniques available for biomass thermo-chemical conversion; microwave assisted pyrolysis (MAP) seems to be the very promising. The principles of microwave technology were reviewed and the parameters for the efficient production of bio-oil using microwave technology were summarized. Microwave technology by itself cannot efficiently produce high quality bio-oil products, catalysts are used to improve the reaction conditions and selectivity for valued products during MAP. The catalysts used to optimize MAP are revised in the development of this article. The origins for bio-oils that are phenol rich or hydrocarbon rich are reviewed and their experimental results were summarized. The kinetics of MAP is discussed briefly in the development of the article. Future prospects and scientific development of MAP are also considered in the development of this article.

Production of bio-oil and biochar from soapstock via microwave-assisted co-catalytic fast pyrolysis

In this study, production of bio-oil and biochar from soapstock via microwave-assisted co-catalytic fast pyrolysis combining the advantages of in-situ and ex-situ catalysis was performed. The effects of catalyst and pyrolysis temperature on product fractional yields and bio-oil chemical compositions were investigated. From the perspective of bio-oil yield, the optimal pyrolysis temperature was 550°C. The use of catalysts reduced the water content, and the addition of bentonite increased the bio-oil yield. Up to 84.16wt.% selectivity of hydrocarbons in the bio-oil was obtained in the co-catalytic process. In addition, the co-catalytic process can reduce the proportion of oxygenates in the bio-oil to 15.84wt.% and eliminate the N-containing compounds completely. The addition of bentonite enhanced the BET surface area of bio-char. In addition, the bio-char removal efficiency of Cd²⁺ from soapstock pyrolysis in presence of bentonite was 27.4wt.% higher than without bentonite.

Fast microwave-assisted catalytic co-pyrolysis of lignin and low-density polyethylene with HZSM-5 and MgO for improved bio-oil yield and quality

Fast microwave-assisted catalytic co-pyrolysis of lignin and low-density polyethylene (LDPE) with HZSM-5 and MgO was investigated. Effects of pyrolysis temperature, lignin to LDPE ratio, MgO to HZSM-5 ratio, and feedstock to catalyst ratio on the products yields and chemical profiles were examined. 500°C was the optimal co-pyrolysis temperature in terms of the maximum bio-oil yield. The proportion of aromatics increased with increasing LDPE content. In addition, with the addition of LDPE (lignin/LDPE=1/2), methoxyl group in the phenols was completely removed. A synergistic effect was found between lignin and LDPE. The proportion of aromatics increased and alkylated phenols decreased with increasing HZSM-5 to MgO ratio. The bio-oil yield increased with the addition of appropriate amount of catalyst and the proportion of alkylated phenols increased with increasing catalyst to feedstock ratio.

Recent progress on biomass co-pyrolysis conversion into high-quality bio-oil

Co-pyrolysis of biomass with abundantly available materials could be an economical method for production of bio-fuels. However, elimination of oxygenated compounds poses a considerable challenge. Catalytic co-pyrolysis is another potential technique for upgrading bio-oils for application as liquid fuels in standard engines. This technique promotes the production of high-quality bio-oil through acid catalyzed reduction of oxygenated compounds and mutagenic polyaromatic hydrocarbons. This work aims to review and summarize research progress on co-pyrolysis and catalytic co-pyrolysis, as well as their benefits on enhancement of bio-oils derived from biomass. This review focuses on the potential of plastic wastes and coal materials as co-feed in co-pyrolysis to produce valuable liquid fuel. This paper also proposes future directions for using this technique to obtain high yields of bio-oils.