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Catalytic pyrolysis technology proves to be a highly effective approach for waste cooking oil management. However, high-pressure drops and easy deactivation of powder catalysts hinder the industrialization of this technology. In this study, a bifunctional SiC ball (ZSM-5/SiC ball structured) catalyst was prepared to produce monocyclic aromatics. Bifunctional SiC ball catalyst demonstrates notable microwave-responsive properties and remarkable catalytic efficacy. Results showed that the content of monocyclic aromatics under BFSB catalysis with microwave heating was the highest. Weight hourly space velocity is no longer one of the main factors affecting microwave-assisted catalytic pyrolysis under bifunctional SiC ball catalyst. Monocyclic aromatics content did not decrease significantly and was still higher than 86% when space velocity increased from 30 h -1 to 360 h -1 . The highest space velocity could only be 180 h -1 under Powder ZSM-5, and the content of the monocyclic aromatics dropped rapidly to 67.68%. Furthermore, even after five operating cycles, the content of monocyclic aromatics with bifunctional SiC ball catalyst continues to surpass the initial content observed with Powder ZSM-5 at 500 °C and 180 h -1 . Related characterizations revealed that coking is the primary cause of catalyst deactivation for both catalyst types; however, the bifunctional SiC ball catalyst exhibits a 29.1% lower occurrence of polyaromatic coke formation compared to Powder ZSM-5., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A novel Silicon carbide (SiC) foam ceramic based ZSM-5/SiC nanowires microwave-responsive catalyst was developed to upgrade the pyrolysis volatiles in a microwave-assisted series system (both the pyrolysis and catalytic systems were heated by microwave). The growth of SiC nanowires was helpful for the ZSM-5 growth on the SiC foam ceramic. Because the specific surface area of SiC foam ceramic was improved. The dielectric properties of the composite catalyst were improved due to the growth of SiC nanowires. Bio-oil composition analysis showed that area percentage of hydrocarbons and aromatic hydrocarbons could reach 80.89% and 40.48% at catalytic temperature of 450 ℃and 500 ℃, respectively. The microwave-responsive composite catalyst had good aromatization performance in microwave-assisted series system due to high dielectric properties and specific surface area. The composite catalyst performed well after five-cycle regeneration, and the hydrocarbon content could still reach 76.40%, which is 80.89% for the original catalyst., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In light of the knowledge gap in the scale-up of microwave-assisted pyrolysis technology, this study developed a continuous microwave-assisted pyrolysis (CMAP) system and examined its feasibility for syngas production. Wood pellets were pyrolyzed in the system under various temperatures, and the product distribution and energy efficiency were investigated. At a processing temperature of 800 °C, the CMAP system obtained a high quality producer gas (lower heating value 18.0 MJ/Nm 3 and a 67 vol% syngas content) at a yield of 72.2 wt% or 0.80 Nm 3 /kg d.a.f. wood, outperforming several conventional pyrolysis processes probably due to two factors: 1) reactions between primary tar and biochar enhanced by microwave irradiation, and 2) the absence of carrier gas in the process. Energy efficiency of the process was also assessed. Potentially the electricity consumption could be reduced from 7.2 MJ to 3.45 MJ per kg of wood, enabling net electricity production from the process., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The conventional studies on the preparation of nanocellulose used a high concentration of sulfuric acid that is difficult to remove and recover. A biochar-based solid acid with magnetic properties was developed to hydrolyze cellulose to prepare nanocellulose in this work. Two different methods were selected to investigate the properties of the synthesized magnetic carbon-based solid acids. The synthesized catalysts were characterized by SEM, TEM, XRD, NH3-TPD and FT-IR. The experimental results showed that two solid acids by the microwave-assisted synthesis had good magnetic properties by a magnet adsorption. Analysis by SEM and TEM showed that the two solid acids had rich pore structures. According to mineral element analysis, both solid acids contained high sulfur content. The solid acid was an amorphous carbon structural material with a surface rich in active groups. The catalytic activity of the biochar-based solid acids in cellulose hydrolysis to prepare nano-scale cellulosic material was evaluated. It was found that magnetic biochar-based solid acid (MBC-SA1) could achieve a high yield, which produced up to 57.68% for hydrolyzing cellulose into nanometers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The composite catalysts were synthesized with SiC powder and ZSM-5 and were characterized by Brunauer-Emmett-Teller, X-ray diffraction, thermogravimetric analysis, pyridine-infrared spectroscopy, and scanning electron microscopy. The catalysts showed a high heating rate and excellent catalytic performance for pyrolysis vapors, and the product fractional distribution and chemical compositions of bio-oil in a tandem system (microwave pyrolysis and microwave ex-situ catalytic reforming) was examined. Experimental results confirmed the quality of bio-oil produced by the microwave-induced catalytic reforming was better than that product through electric heating. Additionally, 36.94 wt% of bio-oil was obtained using the catalyst with 20%ZSM-5/SiC under the following conditions: feed-to-catalyst ratio, 2:1; pyrolysis temperature, 550 °C; and catalytic temperature, 350 °C. The selectivities of hydrocarbons reached up to 75.88%. After five cycles, the activity of the regenerated composite catalyst was retained at 95% of the original catalyst., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Microwave-assisted co-pyrolysis of low hydrogen-to-carbon and high hydrogen-to-carbon effective ratio materials with the aid of HZSM-5 and MCM-41 is a promising technique to improve the bio-oil quality. The low content of hydrocarbons and short life cycle of catalyst limit the application of pyrolysis technology in biomass energy conversion. The effects of catalytic temperature, and HZSM-5-to-MCM-41, feedstock-to-catalyst, and straw-to-soapstock ratios on the yield and composition of bio-oil were studied in this work. The quality of bio-oil during biomass pyrolysis can be improved by adjusting the operating conditions. The optimal catalytic temperature, and ratios of HZSM-5-to-MCM-41, feedstock-to-catalyst, and straw-to-soapstock were 400 °C, 1:1, 2:1, and 1:2, respectively. The addition of MCM-41 was beneficial in prolonging the life of HZSM-5 since the macromolecular compounds cracked when MCM-41 was added which restrain the generation of coke. The co-pyrolysis of soapstock with straw advanced the deoxygenation of oxygen-containing compounds especially phenol from straw during pyrolysis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The integrated process of formic acid pretreatment and pyrolysis of bamboo sawdust (BS) under microwave irradiation is developed to produce high-quality bio-oil in this study. Experimental results indicated that microwave-assisted formic acid (MFA) pretreatment was able to reduce the contents of hydrogen, ash, and volatile in biomass. In the meanwhile, a distinct increase in the higher heating value of pretreated BS was observed. Although a higher pretreatment temperature led to lower mass yield, the corresponding energy yield of solid product was remarkably higher. X-ray diffraction and Fourier transfer infrared spectrometry analyses of pretreated BS suggested that MFA pretreatment could destruct the pristine structure of BS. Therefore, thermal properties of pretreated BS were significantly altered in terms of thermal stability and decomposition temperature according to thermogravimetric analysis. Microwave-assisted pyrolysis of pretreated samples could produce less acids, phenols, and ketones but more sugars, especially gluopyranose. Furthermore, the relevant mechanism of microwave-assisted pyrolysis of pretreated BS was interpreted. In sum, MFA was a feasible and promising technology to improve the quality of bio-oil from microwave pyrolysis of biomass., (Copyright © 2019 Elsevier Inc. All rights reserved.)

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., (Copyright © 2019. Published by Elsevier Ltd.)

Continuous fast microwave catalytic co-pyrolysis of Alternanthera philoxeroides and peanut soapstock was studied using HZSM-5 as catalyst. The effects of catalyst temperature, feedstock-to-catalyst ratio, and A. philoxeroides-to-peanut soapstock ratio on the yield and composition of bio-oil were studied. Experimental results showed that the optimum catalyst temperature was 400 °C. The catalyst increased the proportion of aromatics but reduced the bio-oil yield. The optimum feedstock-to-catalyst ratio was 2:1. A. philoxeroides presented a significant synergistic effect with peanut soapstock, which facilitated the production of aromatics in the bio-oil. The optimum A. philoxeroides-to-peanut soapstock ratio was 1:2., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, a continuous fast microwave-assisted pyrolysis system was developed to produce bio-oil, gas, and biochar from rice straw and Camellia oleifera shell. The effects of different pyrolysis temperatures (400 °C, 500 °C, and 600 °C) and feed rates (rice straw: 25, 45, and 66 g/min; C. oleifera shell: 100, 200, and 400 g/min) on bio-oil production were investigated. Experimental results showed that the yields of bio-oil (31.86 wt%) and gas (54.49 wt%) produced by the microwave-assisted pyrolysis of rice straw increased with increasing temperature. By contrast, the yields of bio-oil (27.45 wt%) and biochar (35.47 wt%) produced by the pyrolysis of C. oleifera shell decreased with increasing temperature. The contents of phenols, aldehydes, and alcohols in bio-oil produced from the shell were higher than those in bio-oil derived from rice straw., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Considering a series of issues facing the application of catalysts in large scale catalytic fast pyrolysis systems, a novel composite catalyst of ZSM-5 coatings on SiC foam supports was developed and tested for ex-situ catalytic upgrading of the pyrolytic vapors. Different configurations of catalysts placement were compared and the results showed the composite catalyst could significantly improve the bio-oil quality without significantly reducing the yield. The effect of catalyst to biomass ratio on the product yields and bio-oil composition was studied and the results showed that increasing catalyst to biomass ratio could improve the quality of bio-oil at the cost of its yield. In addition, the composite catalyst can maintain its activity until a catalyst to biomass ratio of 1/10, outperforming ZSM-5 in other configurations reported in literature. Furthermore, the composite catalysts could be regenerated and reused while well preserving its material properties and catalytic activity after seven reaction-regeneration cycles., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Fast microwave-assisted catalytic co-pyrolysis of Chromolaena odorata (C. odorata) and soybean soapstock with HZSM-5 as an ex-situ catalyst was investigated. Effects of catalytic temperature, feedstock: catalyst ratio and C. odorata: soybean soapstock ratio on the yield and composition of the bio-oil were discussed. Results showed that catalytic temperature greatly influenced the bio-oil yield. Co-pyrolysis of C. odorata and soybean soapstock improved the bio-oil yield, and the maximum bio-oil yield of 55.14% was obtained at 250 °C. However, the addition of HZSM-5 decreased bio-oil yield but improved the quality of bio-oil. Moreover, the proportion of oxygen-containing compounds decreased dramatically with the addition of soybean soapstock. The C. odorata: soybean soapstock ratio of 1:2 and feedstock: catalyst ratio of 2:1 were the optimal condition to upgrade the bio-oil. In addition, the resulted biochar contained various essential elements and could be used as soil repair agent., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The controversial synergistic effect between brown coal and biomass during co-pyrolysis deserves further investigation. This study detailed the oil production from microwave-assisted co-pyrolysis of brown coal (BC) and corn stover (CS) at different CS/BC ratios (0, 0.33, 0.50, 0.67, and 1) and pyrolysis temperatures (500, 550, and 600 °C). The results showed that a higher CS/BC ratio resulted in higher oil yield, and a higher pyrolysis temperature increased oil yield for brown coal and coal/corn mixtures. Corn stover and brown coal showed different pyrolysis characteristics, and positive synergistic effect on oil yield was observed only at CS/BC ratio of 0.33 and pyrolysis temperature of 600 °C. Oils from brown coal mainly included hydrocarbons and phenols whereas oils from corn stover and coal/corn mixtures were dominated by ketones, phenols, and aldehydes. Positive synergistic effects were observed for ketones, aldehydes, acids, and esters whereas negative synergistic effects for hydrocarbons, phenols and alcohols., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The co-pyrolysis of pretreated lignin and soapstock was carried out to upgrade vapors under microwave irradiation. Results showed that the yield of 29.92-42.21 wt% of upgraded liquid oil was achieved under varied pretreatment conditions. Char yield decreased from 32.44 wt% for untreated control to 24.35 wt% for the 150 °C pretreated samples. The increased temperature, irradiation time and acid concentration were conducive to decrease the relative contents of phenols and oxygenates in liquid oils. The main components of the liquid oil were gasoline fraction (mono-aromatics and C5-C12 aliphatics), which ranged from 57.38 to 71.98% under various pretreatment conditions. Meanwhile, the diesel fraction (C12+ aliphatics) ranged from 13.16 to 22.62% from co-pyrolysis of pretreated lignin and soapstock, comparing with 10.18% of C12+ aliphatics from co-pyrolysis of non-pretreated lignin and soapstock. A possible mechanism was proposed for co-pyrolysis of pretreated lignin and soapstock for upgraded liquid oils., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This study performed microwave-assisted acid pretreatment on pure lignin. The effects of microwave temperature, microwave time, and hydrochloric acid concentration on characteristics and pyrolysis behavior of lignin were examined. Results of ultimate analysis revealed better properties of all pretreated samples than those of raw lignin. Fourier transform infrared spectroscopy analysis showed breakage of βO4 bond and aliphatic side chain, decrease in OH groups, and formation of CO groups in pretreatment. Microwave temperature exerted more significant influence on lignin structure. Thermal stability of treated lignin was improved and insensitive to short microwave time and acid concentration under mild conditions. Resulting from improved alkyl-phenols and decreased alkoxy-phenols, microwave-assisted acid pretreatment of lignin yielded bio-oil with excellent quality. Total yield of phenols in pyrolysis vapors (200 °C) improved to 14.15%, whereas that of guaiacols decreased to 22.36%. This study shows that microwave-assisted acid pretreatment is a promising technology for lignin conversion., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In-situ and ex-situ catalytic upgrading with HZSM-5 of vapors from microwave-assisted pyrolysis of lignin were studied. The in-situ process produced higher bio-oil and less char than ex-situ process. The gas yield was similar for both processes. The ex-situ process had higher selectivity to aromatics and produced more syngas and less CO 2 than the in-situ process. Additional experiments on ex-situ process found that the bio-oil yield and coke deposition decreased while the gas yield increased at higher catalyst-to-lignin ratios and catalytic upgrading temperatures. The increased catalyst-to-lignin ratio from 0 to 0.3 reduced the selectivity of methoxy phenols from 73.7% to 22.6% while increased that of aromatics from 1.1% to 41.4%. The highest selectivity of alkyl phenols (31.9%) was obtained at 0.2 of catalyst-to-lignin ratio. Higher catalytic temperatures favored greater conversion of methoxy phenols to alkyl phenols and aromatics. Appropriate catalyst-to-lignin ratio (0.3) together with higher catalytic temperatures favored syngas formation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In the present study, the effect of temperature and residence time during microwave hydrothermal pretreatment (MHT) on hydrochar properties and pyrolysis behaviors was investigated. Experimental results indicated that higher heating value (HHV) and fixed carbon content gradually increased with increased pretreatment severity. Obvious reduction of oxygen content was found under MHT at 230°C-15min and 210°C-35min. Although lower mass yield was observed under severe conditions, corresponding energy yield was relatively higher. Crystallinity indexes of hydrochar demonstrated an upward trend with increased residence time. Unlike hydroxyl group, dissociation of acetyls was more favorable under prolonged residence time rather than increased temperature. Peaks in thermogravimetric and derivative thermogravimetric curves shifted to higher temperature region under severe conditions, indicating better thermal stability. Py-GC/MS analysis suggested that acids content was decreased but sugars increased with increased MHT severity. Moreover, compared to temperature, residence time was mainly responsible for acetic acid formation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Microwave-assisted pyrolysis is an important approach to obtain bio-oil from biomass. Similar to conventional electrical heating pyrolysis, microwave-assisted pyrolysis is significantly affected by feedstock characteristics. However, microwave heating has its unique features which strongly depend on the physical and chemical properties of biomass feedstock. In this review, the relationships among heating, bio-oil yield, and feedstock particle size, moisture content, inorganics, and organics in microwave-assisted pyrolysis are discussed and compared with those in conventional electrical heating pyrolysis. The quantitative analysis of data reported in the literature showed a strong contrast between the conventional processes and microwave based processes. Microwave-assisted pyrolysis is a relatively new process with limited research compared with conventional electrical heating pyrolysis. The lack of understanding of some observed results warrant more and in-depth fundamental research., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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 Cd 2+ from soapstock pyrolysis in presence of bentonite was 27.4wt.% higher than without bentonite., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This study investigated fast microwave-assisted catalytic co-pyrolysis of corn stover and scum for bio-oil production with CaO and HZSM-5 as the catalyst. Effects of reaction temperature, CaO/HZSM-5 ratio, and corn stover/scum ratio on co-pyrolysis product fractional yields and selectivity were investigated. Results showed that co-pyrolysis temperature was selected as 550°C, which provides the maximum bio-oil and aromatic yields. Mixed CaO and HZSM-5 catalyst with the weight ratio of 1:4 increased the aromatic yield to 35.77 wt.% of feedstock, which was 17% higher than that with HZSM-5 alone. Scum as the hydrogen donor, had a significant synergistic effect with corn stover to promote the production of bio-oil and aromatic hydrocarbons when the H/C(eff) value exceeded 1. The maximum yield of aromatic hydrocarbons (29.3 wt.%) were obtained when the optimal corn stover to scum ratio was 1:2., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

In this study, fast microwave-assisted catalytic pyrolysis of sewage sludge was investigated for bio-oil production, with HZSM-5 as the catalyst. Pyrolysis temperature and catalyst to feed ratio were examined for their effects on bio-oil yield and composition. Experimental results showed that microwave is an effective heating method for sewage sludge pyrolysis. Temperature has great influence on the pyrolysis process. The maximum bio-oil yield and the lowest proportions of oxygen- and nitrogen-containing compounds in the bio-oil were obtained at 550°C. The oil yield decreased when catalyst was used, but the proportions of oxygen- and nitrogen-containing compounds were significantly reduced when the catalyst to feed ratio increased from 1:1 to 2:1. Essential mineral elements were concentrated in the bio-char after pyrolysis, which could be used as a soil amendment in place of fertilizer. Results of XRD analyses demonstrated that HZSM-5 catalyst exhibited good stability during the microwave-assisted pyrolysis of sewage sludge., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In the present study, a microwave-assisted biomass gasification system was developed for syngas production. Three catalysts including Fe, Co and Ni with Al2O3 support were examined and compared for their effects on syngas production and tar removal. Experimental results showed that microwave is an effective heating method for biomass gasification. Ni/Al2O3 was found to be the most effective catalyst for syngas production and tar removal. The gas yield reached above 80% and the composition of tar was the simplest when Ni/Al2O3 catalyst was used. The optimal ratio of catalyst to biomass was determined to be 1:5-1:3. The addition of steam was found to be able to improve the gas production and syngas quality. Results of XRD analyses demonstrated that Ni/Al2O3 catalyst has good stability during gasification process. Finally, a new concept of microwave-assisted dual fluidized bed gasifier was put forward for the first time in this study., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A novel concept of fast microwave assisted pyrolysis (fMAP) in the presence of microwave absorbents was presented and examined. Wood sawdust and corn stover were pyrolyzed by means of microwave heating and silicon carbide (SiC) as microwave absorbent. The bio-oil was characterized, and the effects of temperature, feedstock loading, particle sizes, and vacuum degree were analyzed. For wood sawdust, a temperature of 480°C, 50 grit SiC, with 2g/min of biomass feeding, were the optimal conditions, with a maximum bio-oil yield of 65 wt.%. For corn stover, temperatures ranging from 490°C to 560°C, biomass particle sizes from 0.9mm to 1.9mm, and vacuum degree lower than 100mmHg obtained a maximum bio-oil yield of 64 wt.%. This study shows that the use of microwave absorbents for fMAP is feasible and a promising technology to improve the practical values and commercial application outlook of microwave based pyrolysis., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The pyrolysis of Chlorella sp. was carried out in a microwave oven with char as microwave reception enhancer. The results indicated that the maximum bio-oil yield of 28.6% was achieved under the microwave power of 750 W. The bio-oil properties were characterized with elemental, GC-MS, GPC, FTIR, and thermogravimetric analysis. The algal bio-oil had a density of 0.98 kg/L, a viscosity of 61.2 cSt, and a higher heating value (HHV) of 30.7 MJ/kg. The GC-MS results showed that the bio-oils were mainly composed of aliphatic hydrocarbons, aromatic hydrocarbons, phenols, long chain fatty acids and nitrogenated compounds, among which aliphatic and aromatic hydrocarbons (account for 22.18% of the total GC-MS spectrum area) are highly desirable compounds as those in crude oil, gasoline and diesel. The results in this study indicate that fast growing algae are a promising source of feedstock for advanced renewable fuel production via microwave-assisted pyrolysis (MAP)., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Lignin biochar-catalytic depolymerization using biochar Fe-600, Fe-800, Ni-600, Ni-800 catalysts under microwave-heating (180 °C for 30 min) was explored in an ethanol/formic acid (1:1) media. Non-catalyst depolymerization was also studied and compared with the biochar-catalysts results. Characteristics of the bio-char catalysts were analyze by BET, XRD, and FT-IR. GPC, FT-IR, and MALDI-TOF MS spectrometry were also used to characterize the depolymerization products. The experimental results showed that the SBET, Vt, and Vmec and average pore diameter of the biochars are considerably dependent on the preparation temperature and type of cation (Ni2+ or Fe3+). The maximum yield of bio-oil product was obtained as 85 wt% with the addition of biochar Ni-600 and the total amount of oligomers or monomers with a molecular weight of 164 to 446 reaches 80.4%. [ABSTRACT FROM AUTHOR]

The effects of microwave-assisted acid pretreatment on the characteristics and pyrolysis behavior of moso bamboo sawdust (BS) were investigated by ultimate, Fourier transform infrared spectroscopy, thermogravimetric (TG), and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) analyses in this study. Microwave temperature (100 °C–200 °C), reaction time (30 min–90 min), and acid concentration (0.5 M–1.5 M) were the main influencing factors. Results of ultimate analysis indicated that the properties of the pretreated samples are better than those of the raw BS. Moreover, appropriately reducing the oxygen and ash contents and increasing the microwave temperature promoted decarboxylation and dehydration during pretreatment. Microwave-assisted acid pretreatment decreased the acetyl groups and hydrogen bonds. Of the three main influencing factors affecting the structure of moso BS, microwave temperature was the most important. TG analysis results indicated that the thermostability of the pretreated samples is improved after pretreatment. Moreover, the pyrolysis behavior of moso BS is insensitive to the reaction time and acid concentration under mild conditions. The relative contents of acids, furans, aldehydes, and ketones derived from the pretreated samples decreased according to the results of Py-GC/MS. Meanwhile, the relative glucopyranose and phenol contents of the pretreated samples are higher than those of the raw moso BS and achieve the maximum values of 48.31% and 20.18%, respectively, at 200 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of metal ions on microwave absorption properties of soap was studied. • The larger the metal ion radius, the greater the heating rate. • Divalent metal soap cannot be heated to the goal temperature by absorbing microwaves. • Microwave pyrolysis promotes aromatization and the release of CO, H 2 and CH 4. • The radius of metal ions affects the strengthening effect of microwaves. The pyrolysis of metal soaps to produce hydrocarbon rich fuel has been studied extensively. However, the combined effects of microwave radiation and metal ion types on hydrocarbon production have not been addressed. In this study, the microwave and conventional pyrolysis experiments were conducted on five metal soaps (Li soap, Na soap, K soap, Ca soap, Mg soap). The results demonstrated that the metal ions at the carboxyl end of the soap enhanced the polarity of the reactants, leading to a rapid increase in temperature under microwave conditions. With the ion radius increasing, the heating rate increased gradually. Compared with conventional pyrolysis, microwave pyrolysis exhibited a more rapid heating rate, a higher degree of carbon chain fracture, and a greater abundance of small olefin compounds, which promoted aromatization reaction and the release of CO, H 2 and CH 4. In addition, the composition of the pyrolysis products derived from different metal soaps is affected by the characteristics of metal ions. As the radius of metal ions increased, the oxygen content in the liquid products decreased gradually, while the carbon content increased. The strengthening effect of microwave was further analyzed. With the increase in the radius of metal ions, the strengthening effect of microwaves on olefins formation was gradually weakened, while the inhibiting effect on alkanes formation was gradually enhanced. The structure of carboxylate network is affected by the radius of metal ions, which results in the regular change of the strengthening effect of microwave on olefins and other products. This study is highly significant in guiding the pyrolysis of soapstock waste to prepare olefins and alkanes with high efficiency and low energy consumption. [ABSTRACT FROM AUTHOR]

Microwave-assisted catalytic co-pyrolysis of soybean straw and soapstock was investigated by using silicon carbide ceramic foam as catalyst. The study determined the effects of catalytic temperature, feed-to-catalyst ratio, and soybean straw-to-soapstock ratio on product yield and chemical composition. Experimental results indicated high yield and ratio of hydrocarbon in bio-oil were observed at a catalytic temperature of 350 °C. The use of a catalyst enhanced the hydrocarbon proportion at the expense of decreased in bio-oil yield. A significant synergistic effect was observed during co-pyrolysis of soybean straw and soapstock, and this effect facilitated hydrocarbon production from bio-oil. [ABSTRACT FROM AUTHOR]

Microwave-assisted pyrolysis of Chinese tallow kernel oil with silicon carbide (SiC)-foamed ceramic catalyst in a downdraft reactor was carried out in this study. In this paper, we studied the influence of catalytic temperature, catalyst-to-feed ratio, and feeding rate on product distribution and chemical components of bio-oil. The aromatic proportion reached a maximum value of 89.707 wt% when catalytic conditions were set as follows: 300 °C catalytic temperature, 1:2 catalyst/feedstock ratio, and 1 ml/min feed rate. Fourier-transform infrared spectra were consistent with the results obtained from gas chromatography–mass spectrometry. Their outstanding thermal stability allowed SiC-foamed ceramics to perform well in five cycles of repeated experiments under optimal conditions. These results indicate that the SiC-foamed ceramics are promising catalysts for aromatic production in microwave-assisted pyrolysis of Chinese tallow kernel oil in a downdraft reactor. This pathway can also improve the application prospects of microwave pyrolysis technology. [ABSTRACT FROM AUTHOR]

Solvolysis approach is an efficient pathway to covert solid biomass into different end products since it can provide a mild environment and a single-phase condition. A comparative study on various alcohols-assisted liquefaction of lignin has been carried out using sulfuric acid as catalyst under microwave condition. Methanol and ethanol showed a higher conversion rate compared to other alcohols. Both liquefied products and residues have been investigated using gel permeation chromatography–high-performance liquid chromatography (GPC–HPLC), Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM) and Thermogravimetric (TG) analysis. The results showed that methanol and ethanol as solvents achieved a higher conversion rate, meantime, the molecular weight of liquefied products was dramatically lower than those of other alcohols. The FT-IR indicated that there were obvious differences in the contents of carbonyl, methyl and hydroxyl group in the liquefied products with various alcohols as solvents. The solid residue exhibited a big difference in microstructure morphology after depolymerization, in addition, the resulted solid residue from methanol solvents showed a higher thermal stability and char yield, which can be used as a fire retardant in composite materials. [ABSTRACT FROM AUTHOR]

Obtaining energy from brown coal is an everlasting pursuit. This study detailed the oil production from microwave-assisted pyrolysis of a low rank American brown coal. The effects of feedstock load (20, 30, 40, 50, and 60 g), pyrolysis temperature (550, 600, 650, 700, and 750 °C) and heating time (10, 15, 20, 25, and 30 min) on the oil yields and compounds were also investigated. The results showed that the oil yields obtained were 13.17–22.97 wt% of the brown coal on ash free basis, and it increased initially and then decreased with increasing feedstock load, pyrolysis temperature, and heating time. Light oil and heavy oil accounted for 33.49–65.08 wt% and 34.92–61.94 wt% of the oil yields, and the compound weights were 1.21–5.41 wt% and 90.75–98.14 wt%, respectively. The highest oil yield was achieved at the feedstock load of 50 g, pyrolysis temperature of 700 °C and heating time of 20 min, and it was very close to the oil yield at high heating rates of 2000–10,000 °C/s for the electrical heating pyrolysis. The results obtained from this study not only detailed the oil yields and compounds obtained from microwave-assisted pyrolysis of a brown coal but also demonstrated the effects of feedstock load, pyrolysis temperature and heating time on the oil production. The results also indicated that microwave-assisted pyrolysis may be a more suitable technology for obtaining oil from brown coals than electrical heating pyrolysis. [ABSTRACT FROM AUTHOR]

Fast microwave-assisted catalytic pyrolysis (fMACP) of soapstock for hydrocarbon-rich bio-oil using different catalysts was investigated in this study. Effects of catalyst, pyrolysis temperature and catalyst to feed ratio on product fractional yields and chemical composition were studied. Experimental results indicated that the use of catalyst increased the relative content of hydrocarbons and selectivity of aromatics. Moreover, HZSM-5 catalyst enhanced the bio-oil yield. When HZSM-5 zeolite was used as a catalyst, 600 °C was the optimal pyrolysis temperature, which provides the maximum bio-oil yield and high content of hydrocarbons. At the cost of the decrease of bio-oil yield, the increase of catalyst to feed ratio increased the relative content of hydrocarbons from 65.41% to 88.59% and selectivity of aromatics from 5.99% to 29.46%. In addition, the analytical results of bio-char show that bio-char with micropore structure and high contents of the essential plant nutrients and micronutrients can be used as a soil amendment to improve soil productivity. [ABSTRACT FROM AUTHOR]

Microwave-assisted catalytic fast co-pyrolysis using HZSM-5 as catalyst was tested on soapstock and waste tire. Effects of co-pyrolysis temperature, catalyst to feed ratio and soapstock to tire ratio on product fractional yields and chemical composition were studied. Experimental results indicated that the optimal co-pyrolysis temperature was 550 °C, where the highest yield of bio-oil and proportion of aromatics in the bio-oil was obtained. The use of catalyst enhanced the proportion of aromatics, but reduced the yield of bio-oil. Waste tire presented a significant synergistic effect with soapstock to facilitate the production of aromatics in the bio-oil. In addition, the char as a by-product can be used as soil amendment or solid fuel. [ABSTRACT FROM AUTHOR]

Understanding the dissolving selectivity of ionic liquids (ILs) for cellulose, hemicellulose, and lignin in plant cell wall is critical to explore new ILs for efficient pretreatment of lignocellulosic biomass. Here, the bamboo powder was treated at 150 ℃ under microwave irradiation by 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-butyl-3-methylimidazolium acetate (BmimAc) which had the different anions. The recovered bamboo powder and lignin samples were characterized. It indicated that the solubilities of bamboo powder in BmimCl and BmimAc were 27.04 and 7.00 g/100 g IL, respectively. A large amount of polysaccharides, especially hemicellulose, were possibly degraded by BmimCl, resulting in a low recovery rate (24.17 %) of bamboo powder with high content of lignin (41.81 %). The dissolving selectivity of BmimCl for the three main components was in the order: hemicellulose>cellulose>lignin, while that of BmimAc was in a different order: lignin>cellulose>hemicellulose. The dissolving selectivity of BmimAc was less obvious than that of BmimCl. The pretreatment of bamboo powder with BmimCl and BmimAc could greatly improve the yield of reducing sugar. BmimAc performed stronger ability than BmimCl to destroy the crystal structure of cellulose. Both the bamboo lignins extracted by BmimCl and BmimAc were syringyl (S)/guaiacyl (G)/ p -hydroxyphenyl (H) type with different S/G/H ratios of 10.11/5.32/1.00 and 7.61/2.47/1.00, respectively. The lignin extracted by BmimAc was rich in hemicellulose and side alkyl chains. While the β -O-4 bonds in the lignin extracted by BmimCl were seriously broken, leading to the high contents of aliphatic OH, syringyl phenolic OH, and guaiacyl phenolic OH. BmimAc performed weaker ability than BmimCl to damage the lignin structure. • A large quantity of cellulose and hemicellulose were possibly degraded by BmimCl. • The order of dissolving selectivity of BmimCl was hemicellulose>cellulose>lignin. • The order of dissolving selectivity of BmimAc was lignin>cellulose>hemicellulose. • The dissolving selectivity of BmimAc was less obvious than that of BmimCl. • BmimAc performed weaker ability than BmimCl to damage the lignin structure. [ABSTRACT FROM AUTHOR]

Combined with the fact that the poor heat transfer effect of low-density polyethylene (LDPE), the microwave absorption characteristics of spent bleaching clay (SBC) and the synergistic effect of co-pyrolysis, we conducted a study. In this study, microwave-assisted catalytic co-pyrolysis of SBC and LDPE was used to produce bio-oil rich in monocyclic aromatic hydrocarbons (MAHs). Then the conditions of co-pyrolysis, including pyrolysis temperature, catalytic temperature, the ratio of SBC/LDPE and catalytic mass were explored. The findings revealed that SBC and LDPE had a synergistic effect, SBC had microwave absorption characteristics, which could transfer heat to LDPE to improve heating rate. And the high H/C eff of LDPE promoted the deoxidation of the SBC, which could optimize the quality of bio-oil. Compared with 43.69% for LDPE pyrolysis alone and 47.18% for SBC pyrolysis alone, the content of MAHs during co-pyrolysis was 54.92%. The optimum pyrolysis parameter was discovered at the pyrolysis temperature of 550 °C, 450 °C of catalytic temperature, 40:28.5 ratio of SBC to LDPE, 7 g of HZSM-5 mass, 69.89% of MAHs and 16.48% of Polycyclic aromatic hydrocarbons was obtained. [Display omitted] • Microwave-assisted co-pyrolysis of LDPE and spent bleaching clay was studied. • Spent bleaching clay can replace microwave absorbent. • Synergy of co-pyrolysis improved content of monocyclic aromatic hydrocarbons. • Parameters such as temperature, feedstock ratio, and catalyst mass were optimized. [ABSTRACT FROM AUTHOR]

The homogeneous internal heating of solid catalyst during high-temperature conversion reactions is beneficial for reducing of coke formation. However, the non-uniform temperature heating of traditional catalytic reforming process hindered the development. Herein, a dual microwave reaction system with upgrading heating method was built to conduct the catalytic pyrolysis of woody oil over a SiC-MCM41 catalyst. The effects of pyrolysis temperature, catalytic temperature and catalyst to feed ratio were investigated. The pyrolysis behaviors of the four major fatty acids in materials were discussed under optimal reaction conditions with different catalysts. Experimental results showed that microwave catalysis reduced the coke formation and extended the service life of the catalyst and increased the hydrocarbon content to 94.833 wt% (71.409 wt% of aromatics) which may implicate the industrial production. The types of fatty acids have a greater impact on the pyrolysis products than the catalysts, among which the maximum amount of aromatics obtained from the pyrolysis of linolenic acid was 92.43 wt%. This finding provides a partial reference in commercial application for obtaining a high content of target products in the field of single oil pyrolysis in the future. Image 1 • Dual microwave system applied microwave heating to pyrolysis and catalysis. • The composite catalyst and microwave reaction system worked well. • The dual microwave system could increase hydrocarbons to 94.833 wt%. [ABSTRACT FROM AUTHOR]

• Microwave-assisted pyrolysis of lignin with various microwave susceptors was studied. • Thermal decomposition behavior of lignin during microwave pyrolysis was presented. • High temperatures favored the production of syngas (CO + H 2) from lignin pyrolysis. • Methoxyphenols were completely converted from BC induced microwave pyrolysis. • Pyrolysis with AC and BC yielded 74.5% and 70.1% of syngas, respectively. Lignin was pyrolyzed with microwave heating in the presence of different microwave susceptors including silicon carbide (SiC), activated carbon (AC), and biochar (BC). The heating profiles of microwave heating with different susceptors were characterized. With SiC as the susceptor, three distinct heating stages were observed, which were believed to correspond to the three main stages of lignin decomposition. The effects of temperature, susceptor loading weight, and susceptor type on product yield and composition were investigated. Higher pyrolysis temperatures favored char reduction, demethoxylation and alkylation of phenols, and H 2 formation. Higher SiC loading weight promoted the formation of alkyl phenols and syngas (CO and H 2). Compared with SiC, both AC and BC enhanced the production of syngas, accounting for 74.5% and 70.1% in volume percentage, respectively. AC contributed to the highest bio-oil and gas production while BC showed highest selectivity to phenol and alkyl phenols, up to 58.2% and 37.7%, respectively. [ABSTRACT FROM AUTHOR]