Potentiality of combined catalyst for high quality bio-oil production from catalytic pyrolysis of pinewood using an analytical Py-GC/MS and fixed bed reactor

The aim of this study was to investigate the potential of combined catalyst (ZSM-5 and CaO) for high quality bio-oil production from the catalytic pyrolysis of pinewood sawdust that was performed in Py-GC/MS and fixed bed reactor at 500 °C. In Py-GC/MS, the maximum yield of aromatic hydrocarbon was 36 wt% at biomass to combined catalyst ratio of 1:4 where the mass ratio of ZSM-5 to CaO in the combined catalyst was 4:1. An increasing trend of phenolic compounds was observed with an increasing amount of CaO, whereas the highest yield of phenolic compounds (31 wt%) was recorded at biomass to combined catalyst ratio of 1:4 (ZSM-5: CaO - 4:1). Large molecule compounds could be found to crack into small molecules over CaO and then undergo further reactions over zeolites. The water content, higher heating value, and acidity of bio-oil from the fixed bed reactor were 21%, 24.27 MJkg⁻¹, and 4.1, respectively, which indicates that the quality of obtained bio-oil meets the liquid biofuel standard ASTM D7544-12 for grade G biofuel. This research will provide a significant reference to produce a high-quality bio-oil from the catalytic pyrolysis of woody biomass over the combined catalyst at different mass ratios of biomass to catalyst.     

Influence of metal (Fe/Zn) modified ZSM-5 catalysts on product characteristics based on the bench-scale pyrolysis and Py-GC/MS of biomass

In this study, sawdust was selected as the raw material for biomass pyrolysis to obtain organic products. The catalyst was modified with two elements (Fe and Zn). Through analysis of the catalytic products, we attempted to identify a pyrolysis catalyst that can improve the yield of aromatic hydrocarbon products. ZSM-5, modified with Fe and Zn, was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) measurements. Tube furnace and flash pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) were used to comprehensively investigate the characteristics of the products of biomass pyrolysis. The highest yield of phenols was obtained using the Fe-modified ZSM-5 catalyst, which was 18.30% higher than the yield obtained by the pure ZSM-5 catalyst. The lowest yield of acid products was obtained by single-metal-supported catalytic pyrolysis with Fe or Zn, which was 50.66% lower than the yield obtained by direct pyrolysis. During the pyrolysis of biomass using metal-modified catalysts, the production of aromatic hydrocarbons was greatly improved. Among them, compared with direct pyrolysis, the Fe-Zn co-modified ZSM-5 catalyst exhibited the weakest promotion of aromatic hydrocarbon formation, but there was still a 68.50% improvement. Although the co-modified catalyst did not show absolute advantages under the conditions used for this experiment, the improvements in the production of aromatics and phenolic products also showed its potential for improving bio-oil products. Under the action of Fe-modified catalysts, the most abundant components in the gas product were CO and CO₂, which reached levels as high as 53.45% and 15.34%, respectively, showing strong deoxidation capabilities. Therefore, Fe-modified ZSM-5 catalysts were found to better promote the formation of aromatic hydrocarbon products of biomass pyrolysis.     

Non-catalytic and catalytic pyrolysis of Ulva prolifera macroalgae for production of quality bio-oil

Pyrolysis of Ulva prolifera macroalgae (UM), an aquatic biomass, was carried out in a fixed-bed reactor in the presence of three zeolites based catalysts (ZSM-5, Y-Zeolite and Mordenite) with the different catalyst to biomass ratio. A comparison between non-catalytic and catalytic behavior of ZSM-5, Y-Zeolite and Mordenite catalyst in the conversion of UM showed that is affected by properties of zeolites. Bio-oil yield was increased in the presence of Y-Zeolite while decreased with ZSM-5 and Mordenite catalyst. Maximum bio-oil yield for non-catalytic pyrolysis was (38.5 wt%) and with Y-Zeolite catalyst (41.3 wt%) was obtained at 400 °C respectively. All catalyst showed a higher gas yield. The higher gas yield might be attributed to that catalytic pyrolysis did the secondary cracking of pyrolytic volatiles and promoted the larger small molecules. The chemical components and functional groups present in the pyrolytic bio-oils are identified by GC–MS, FT-IR, ¹H-NMR and elemental analysis techniques. Phenol observed very less percentage in the case of non-catalytic pyrolysis bio-oil (9.9%), whereas catalytic pyrolysis bio-oil showed a higher percentage (16.1%). The higher amount of oxygen present in raw biomass reduced significantly when used catalyst due to the oxygen reacts with carbon and produce (CO and CO₂) and water.     

Impact of acid-modified ZSM-5 on hydrocarbon yield of catalytic co-pyrolysis of poplar wood sawdust and high-density polyethylene by Py-GC/MS analysis

Co-pyrolysis of poplar wood sawdust and high-density polyethylene at a mass ratio of 1:1 over acid-modified ZSM-5 was studied by Py-GC/MS at catalyst to feedstock mass ratio of 1:1 to enhance hydrocarbon formation in the pyrolytic vapour. Catalysts were modified by wet impregnation using sulfuric acid (0.1 M, 0.3 M, 0.5 M and 0.7 M). Results showed that acid treatment affects the catalytic activity of ZSM-5 by changing the amount of acid sites. Co-pyrolysis with HDPE resulted in high relative content of olefin(53.32%) than pyrolysis of poplar (16.6%) and significantly reduces the amount of oxygenates except alcohol. In catalytic co-pyrolysis over acid-modified ZSM-5, the share of olefin was between 56.20% and 59.7%, whereas the lowest amount was 49.53% over P-ZSM-5. The relative content of alkane over acid-modified ZSM-5 was in the range of 23.29–25.96% and higher than that with P-ZSM-5 (21.18%). Importantly, ZSM-5 (0.5 M) was most selective one for aromatic hydrocarbon (12.72%), leading to the maximum share of hydrocarbon of 93.18% when the lowest value was 76.84% over P-ZSM-5. Furthermore, ZSM-5 (0.5 M) showed better deoxygenation among catalysts used in this study. This research could be suggested as a reference for the research of co-pyrolysis of biomass and plastic.     

Upgrading of fast pyrolysis bio-oil over Fe modified ZSM-5 catalyst to enhance the formation of phenolic compounds

The present study is aimed to investigate the upgrading of beech sawdust pyrolysis bio-oil through catalytic cracking of its vapors over Fe-modified ZSM-5 zeolite in a fixed bed tubular reactor. The zeolite supported iron catalyst was successfully prepared with varying metal loading ratios (1, 5, 10 wt%) via dry impregnation method and further characterized by BET, XRD, and SEM-EDX techniques. TG/FT-IR/MS analysis was used for the detection of biomass thermal degradation. Product yields of non-catalytic and catalytic pyrolysis experiments were determined and the obtained results show that bio-oil yields decreased in the presence of catalysts. Besides, the bio-oil composition is characterized by GC/MS. It was indicated that the entity of the ZSM-5 and Fe/ZSM-5 catalyst reveal a significant enhancement quality of the pyrolysis products in comparison with non-catalytic experiment. The catalyst increased oxygen removal from the organic phase of bio-oil and further developed the production of desirable products such as phenolics and aromatic compounds.     

Selective catalytic fast pyrolysis of Jatropha curcas residue with metal oxide impregnated activated carbon for upgrading bio-oil

Jatropha curcas waste was subjected to catalytic pyrolysis at 873 K using an analytical pyrolysis–gas chromatography/mass spectrometry in order to investigate the relative effect of various metal oxide/activated carbon (M/AC) catalysts on upgrading bio-oil from fast pyrolysis vapors of Jatropha waste residue. A commercial AC support was impregnated with Ce, Pd, Ru or Ni salts and calcined at 523 K to yield the 5 wt.% M/AC catalysts, which were then evaluated for their catalytic deoxygenation ability and selectivity towards desirable compounds. Without a catalyst, the main vapor products were fatty acids of 60.74% (area of GC/MS chromatogram), while aromatic and aliphatic hydrocarbon compounds were presented at only 11.32%. Catalytic pyrolysis with the AC and the M/AC catalysts reduced the oxygen-containing (including carboxylic acids) products in the pyrolytic vapors from 73.68% (no catalyst) to 1.60–36.25%, with Ce/AC being the most effective catalyst. Increasing the Jatropha waste residue to catalyst (J/C) ratio to 1:10 increased the aromatic and aliphatic hydrocarbon yields in the order of Ce/AC > AC > Pd/AC > Ni/AC, with the highest total hydrocarbon proportion obtained being 86.57%. Thus, these catalysts were effective for deoxygenation of the pyrolysis vapors to form hydrocarbons, with Ce/AC, which promotes aromatics, Pd/AC and Ni/AC as promising catalysts. In addition, only a low yield (0.62–7.80%) of toxic polycyclic aromatic hydrocarbons was obtained in the catalytic fast pyrolysis (highest with AC), which is one advantage of applying these catalysts to the pyrolysis process. The overall performance of these catalysts was acceptable and they can be considered for upgrading bio-oil.     

Enhancing the aromatic hydrocarbon yield from the catalytic copyrolysis of xylan and LDPE with a dual-catalytic-stage combined CaO/HZSM-5 catalyst

The high concentration of oxygenated compounds in pyrolytic products prohibits the conversion of hemicellulose to important biofuels and chemicals via fast pyrolysis. Herein CaO and HZSM-5 was developed to convert xylan and LDPE to valuable hydrocarbons by thermogravimetric analysis (TGA) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and elucidate the reaction mechanism were also investigated in detail. The results indicated that xylan/LDPE copyrolysis was more complicated than pyrolysis of the individual components. LDPE hindered the thermal decomposition and aromatic hydrocarbon formation from xylan at temperatures under 350 °C and had a synergistic effect at high temperatures. 50% LDPE was proven to be more beneficial than other percentages for the formation of monocyclic aromatic hydrocarbons. Simultaneously, the addition of CaO/HZSM-5 significantly reduced the reaction Ea and increased the reaction rate. CaO can effectively improve the deoxygenation and aromatization reaction, enhancing the yield and selectivity of aromatics to a certain extent. The maximum yield of hydrocarbons (96.01%), mono-aromatic hydrocarbons (88.53%) and S_BTXE (85.79%) were obtained at a CaO/HZSM-5 ratio of 1:2, a pyrolysis temperature of 450 °C, a catalytic temperature of 550 °C, a catalyst dose of 1:2 and a xylan-to-LDPE ratio of 1:1 via an ex situ process. The system was dominated by toluene, xylene and alkyl benzene. Diels-Alder reactions of furans and hydrocarbon pool mechanism of nonfuranic compounds improved aromatic formation. This study provides a fundamental for recovering energy and chemicals from pyrolysis of hemicellulose.     

基于镓改性ZSM-5分子筛作用下的环氧树脂催化热解制芳烃反应性能研究

为实现环氧树脂的清洁处置与资源化利用,在一系列金属镓改性的ZSM-5催化体系中进行快速热解实验,并进行了包括氮气吸附-脱附测试、X射线衍射（XRD）、氨气程序升温吸附（NH₃-TPD）、热重分析（TGA）和透射电镜（TEM）在内的全面的催化剂表征,以阐明催化剂的结构特性。镓的改性显著调节了ZSM-5分子筛的布朗斯特/路易斯酸分布和孔隙结构,改善了高温下分子筛的热解脱氧性能,提高了催化剂的择形催化能力。选取镓负载量、热解温度、催化剂用量、热解升温速率和催化剂回用次数为实验变量,探究了热解油组成分布的变化规律。结果表明,与未改性的分子筛相比,镓改性的ZSM-5分子筛显著提高了环氧树脂快速热解过程中芳烃的选择性。通过不同热解条件的研究发现,环氧树脂催化热解制备芳烃的最佳条件为：1Ga-ZSM-5分子筛∶环氧树脂 = 1∶1,热解温度为600℃,热解速率为10℃/ms,此时芳烃总选择性最高可达56.4%,其中更有价值的单环芳烃的相对含量达到31.6%。     

Hydrocracking of Jatropha oil to aromatic compounds over the LaNiMo/ZSM-5 catalyst

The conversion of biomass to produce high-valued chemical aromatic intermediates such as benzene (B), toluene (T), ethylbenzene (E), xylene (X), naphthalene (N) has attached booming interests. Herein, in order to obtain BTEXN aromatics on the hydrocracking of Jatropha oil, several LaNiMo/ZSM-5 catalysts (La loading from 0.5 to 15 wt%) by alkali treatment and metal impregnation methods were synthesized and investigated. Fundamentally, we found the alkali treatment engendered more mesoporosity to ZSM-5 and resulted in higher catalytic activity. It bears emphasis that further metal impregnated catalyst NiMo/ZSM-5 could improve the aromatics yield due to the increase of metal active sites and acidity sites. Besides, we noted that La loading had positive effects on coke reduction, catalytic stability and catalyst lifetime. To sum up, results confirmed the favorable 1 wt% La–NiMo/ZSM-5 had maximum 75 wt% BTEXN yield, longer catalyst lifetime for 100 h and decreased carbon deposits by 1.11%.     

Catalytic pyrolysis of biomass over Fe-modified hierarchical ZSM-5: Insights into mono-aromatics selectivity and pyrolysis behavior using Py-GC/MS and TG-FTIR

Catalytic pyrolysis has recently aroused great interest for the high potential in upgrading bio-oils as renewable energy. However, conventional catalysts often exert diffusion resistance to large intermediate oxygenates. In this study, Fe-modified hierarchical ZSM-5 prepared by alkali and Fe loading of 2, 4, 6, 8 wt% were characterized by the analysis of XRD, BET, TEM, and NH₃-TPD. Catalytic pyrolysis of poplar sawdust via Fe-modified hierarchical ZSM-5 was conducted using Py-GC/MS and TG-FTIR. The results indicated that alkali treatment and Fe loading of the catalyst introduced a hierarchical and porous structure and improved its acidity, leading to high mono-aromatics and olefins selectivity. The hierarchical ZSM-5 with 4 wt% Fe loading exhibited superior performance with high selectivity towards mono-aromatics of 15.30%. TG-FTIR analysis shows the volatiles release characteristics and FTIR spectra were consistent with pyrolysis behavior. Kinetic analysis reveals Fe-modified hierarchical ZSM-5 lowers the apparent activation energy in catalytic pyrolysis of poplar sawdust.     

Catalytic pyrolysis of sweet sorghum bagasse in the presence of two acid catalysts

Sweet sorghum bagasse was pyrolyzed in the presence of two catalysts, ZSM-5 (a widely known commercial zeolite) and HY-340 (a relatively unexplored acid catalyst). The vapors originating from the thermal decomposition were examined by Py-GC/MS in the biomass/catalyst mass ratios of (1:1), (1:2), (1:5) and (1:10) at 450 °C, 550 °C and 650 °C. In the tests without catalysts, the production of both olefins and aromatics increased in response to increasing reaction temperature. In the catalytic pyrolysis in the presence of ZSM-5, the formation of aromatics increased significantly and the formation of oxygenated decreased in response to increasing amounts of catalyst at all the temperatures studied. The highest concentration of aromatics was obtained in the tests at 450 °C with a bagasse/ZSM-5 ratio of (1:10). In the tests with niobic acid, the formation of furans increased with the addition of HY-340 at ratios of (1:1) and (1:2), and the formation of oxygenated decreased in response to the increase in biomass/catalyst ratio at all temperatures mentioned. Area percentages of approximately 54% of olefins were obtained in the assays at bagasse/HY-340 ratios of (1:2) and (1:5) at 650 °C.     

Catalytic conversion of particle board over microporous catalysts

Catalytic pyrolysis of particle board, a type of waste wood that is increasingly produced all over the world, was carried out over three types of zeolite catalysts: HBETA, HZSM-5, and Ga-impregnated HZSM-5 (Ga/HZSM-5). Experiments conducted using a batch reactor showed that the bio-oil yield and gas yield in catalytic pyrolysis were lower and higher than those in non-catalytic pyrolysis, respectively. Analysis of the bio-oil using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) showed that the yields of high-value-added species such as aromatics and phenolics were increased to a large extent by catalytic upgrading, thus increasing the value of the product bio-oil. In particular, HZSM-5 exhibited high selectivity for aromatic compounds, and impregnation of Ga further increased the selectivity. HBETA could cause levoglucosans to decompose completely owing to its large pore size, resulting in increased yields of low-molecular-mass species.     

Preparation of bio-oil derived from catalytic upgrading of biomass vacuum pyrolysis vapor over metal-loaded HZSM-5 zeolites

The Fe-, Co-, Cu-loaded HZSM-5 zeolites were prepared via impregnation method. The upgrading by catalyst on biomass pyrolysis vapors was conducted over modified zeolites to investigate their catalytic upgrading performance and anti-coking performance. The Brønsted acid sites amount on Cu-,Co-loaded HZSM-5 decreased sharply, while that of Lewis both increased. The yield of liquid fraction and refined bio-oil over metal loaded ZSM-5 catalysts decreased, while that of char almost kept constant. The physical property of refined bio-oil was promoted in terms of pH value, dynamic viscosity and higher heating value (HHV). FT-IR analysis revealed that the chemical structure of refined bio-oil obtained over Fe-, Co-, Cu-loaded HZSM-5 zeolites was highly similar. The yield of monocyclic aromatic and aliphatic hydrocarbon over Fe-,Co-loaded HZSM-5 were boosted by around 2.5 times compared with original ZSM-5 zeolites. Data analysis revealed that Cu/HZSM-5 presented the worst deoxygenation ability. The anti-coking capability of Fe/HZSM-5 was obviously better, i.e., the coke content showed an approximate decrease of 38%. Thus, this study provided an efficient Fe/HZSM-5 catalysts for preparation of bio-oil derived from catalytic upgrading of biomass pyrolysis vapor.     

Hydrothermal liquefaction of macroalgae: Influence of zeolites based catalyst on products

Hydrothermal liquefaction (HTL) of Ulva prolifera macroalgae (UP) was carried out in the presence of three zeolites based catalysts (ZSM-5, Y-Zeolite and Mordenite) with the different weight percentage (10–20 wt%) at 260–300 °C for 15–45 min. A comparison between non-catalytic and catalytic behavior of ZSM-5, Y-Zeolite, and Mordenite in the conversion of Ulva prolifera showed that is affected by properties of zeolites. Maximum bio-oil yield for non-catalytic liquefaction was 16.6 wt% at 280 °C for 15 min. The bio-oil yield increased to 29.3 wt% with ZSM-5 catalyst (15.0 wt%) at 280 °C. The chemical components and functional groups present in the bio-oils are identified by GC-MS, FT-IR, ¹H-NMR, and elemental analysis techniques. Higher heating value (HHV) of bio-oil (32.2–34.8 MJ/kg) obtained when catalyst was used compared to the non-catalytic reaction (21.2 MJ/kg). The higher de-oxygenation occurred in the case of ZSM-5 catalytic liquefaction reaction compared to the other catalyst such as Y-zeolite and mordenite. The maximum percentage of the aromatic proton was observed in bio-oil of ZSM-5 (29.7%) catalyzed reaction and minimum (1.4%) was observed in the non-catalyst reaction bio-oil. The use of zeolites catalyst during the liquefaction, the oxygen content in the bio-oil reduced to 17.7%. Aqueous phase analysis exposed that presence of valuables nutrients.     

Catalytic fast pyrolysis of waste pepper stems over HZSM-5

Catalytic fast pyrolysis over HZSM-5 of red pepper stems, a representative agricultural residue material in the southern area of South Korea, was carried out. The SiO₂/Al₂O₃ ratio of the catalyst were 23 and 280. Pyrolysis-gas chromatography/mass spectrometry was used to pyrolyze the pepper stem samples at 550 °C and directly analyze the product distribution. The main product species of the non-catalytic pyrolysis of pepper stems were phenolics, followed by oxygenates and acids. The production of aliphatic and aromatic hydrocarbons was marginal. On the contrary, catalytic pyrolysis over HZSM-5 reduced the fractions of phenolics and acids significantly, while considerably increasing the fractions of aliphatic and aromatic hydrocarbons. The catalytic activity of the HZSM-5 with a SiO₂/Al₂O₃ ratio of 23 was much higher, owing to its much larger amount of strong Brønsted acid sites, than the one with a SiO₂/Al₂O₃ ratio of 280. Conversion of carbohydrate via furans to aromatics over strong acid sites was observed, which was in good agreement with previous studies. This study suggests that the catalytic pyrolysis of lignin-rich biomass over acidic zeolite catalysts can be a promising method to produce valuable chemicals such as aromatic compounds.     

Insights into pyrolysis and catalytic co-pyrolysis upgrading of biomass and waste rubber seed oil to promote the formation of aromatics hydrocarbon

To solve the problem of low aromatic hydrocarbon yield and selectivity in biomass catalytic pyrolysis, we used added oxygen-containing hydrogen supplier of rubber seed oil (RSO) with a higher hydrogen-to-carbon ratio to investigate the thermal decomposition behaviors, kinetic and production distribution of biomass, cellulose and RSO with the weight ratio of 1:2 using thermogravimetric analyzer (TGA) for kinetic analysis and fixed bed reactor with the feed composition of 1.2 g: 0.4 mL/min (Biomass to RSO) for product distribution in non-catalytic and catalytic co-pyrolysis over a HZSM-5 catalyst. The results show that there was a positive synergistic interaction between biomass and RSO according to the difference in weight loss, which could decrease the formation of solid coke at the end of experiment. The addition of the HZSM-5 catalyst can markedly increase the reaction activity, accelerate the reaction rate, and the reaction Ea, leading to a substantial increase in the conversion rate; furthermore, the residual carbon content will decrease, and the activations of Cellulose + RSO + Catalyst and Biomass + RSO + Catalyst are only 50.80 kJ/mol and 62.36 kJ/mol, respectively. The kinetic analysis showed that adding a catalyst did not change the decomposition mechanism. Co-pyrolysis of biomass and RSO could effectively improve the yield and selectivity of aromatics, when the pyrolysis temperature and catalytic temperature were 550 °C and 500 °C, respectively, the mass space velocity of RSO was 0.4 mL/min, the reaction time was 30min, the yields of benzene, toluene, xylene and ethyl benzene (BTXE) were up to 78.77%, and the selectivity of benzene, toluene and xylene was much better. Finally, the coke yield was substantially lower.     

Bio-hydrocarbons through catalytic pyrolysis of used cooking oils and fatty acids for sustainable jet and road fuel production

Used Cooking Oil (UCO) and pure Fatty Acids (FAs) derived from food processing represent sustainable feedstocks for biofuel production. The catalytic and non-catalytic pyrolysis of these residual oils is a possible pathway to advanced biofuel production, alternative to catalytic hydrotreatment, already commercially deployed in large-scale installations. The present work first carried out a literature review of previous research works in the field, which provided the key information to the following implementation of a pilot-scale dedicated experimental work aimed at producing bio-hydrocarbons from residual vegetable oils, with a special focus on paraffinic fuels. Based on the literature survey, 4 different catalysts were selected for the experimental investigation. Catalytic and non-catalytic pyrolysis of UCO was initially carried out in 1.5 kg h⁻¹ (max) feed pilot unit, operated at 500 °C, with the catalytic reactor working at 4 and 2.5 h⁻¹ Weight Hourly Space Velocity (WHSV). Liquid yields and corresponding hydrocarbon fractions were investigated: these initial results suggested to extend the study to catalytic pyrolysis of pure FAs. At T = 500 °C and with activated carbons as catalyst, the total observed hydrocarbon yield mass fraction on UCO and FA increased from 23% (UWHSV = 4 h⁻¹) to 35% (UCO, WHSV = 2.5 h⁻¹) and finally to 40% (FA, WHSV = 2.5 h⁻¹). A slight reduction in the overall liquid yield mass fraction was also observed in this last experiment with FAs (from 63% to ≈49%). Even if the current work on the pilot pyrolyser did not aim at investigating energy and process optimization, including yield maximization and catalyst lifetime, experimental results indicated that catalytic pyrolysis could be a promising way for industrial production of hydrocarbons from low quality lipid-based materials (as it is the case of UCOs) and without requiring hydrogen for catalytic hydrotreatment.     

Effect of zeolite structure on light aromatics formation during upgrading of cellulose fast pyrolysis vapor

Promising technology for the conversion of cellulose to aromatics by catalytic fast pyrolysis (CFP) was investigated using five zeolite catalysts, i.e., 5A, SAPO-34, HY, BETA and HZSM-5. The relationship between the porosity and acidity of different zeolites with product selectivity was studied. The results showed that both the acidity and pore size of the zeolite significantly affected the production of aromatics and coke, especially the bio-oil composition. The bio-oils obtained over 5A or SAPO-34 (small pore<5.5 nm) have relatively high oxygen content. The BTEXN (benzene, toluene, ethylbenzene, xylenes and naphthalene) carbon yields over weak acidic zeolites of HY and BETA are only 6.5% and 9.0%, respectively. Due to the appropriate pore size distribution and acid position, HZSM-5 gave the highest BTEXN carbon yield of 21.1%. Moreover, the coke deposited on the spent zeolites was analyzed by temperature programmed oxidation. Furthermore, three possible mechanisms that the acid sites catalyze vapor towards non-condensable gases, aromatics and coke were also studied. HZSM-5 achieved satisfactory deoxygenation and aromatic production simultaneously, made it a potential catalyst for producing light aromatics from reforming the biomass pyrolytic vapors.     

Catalytic pyrolysis of biomass: Effects of pyrolysis temperature,sweeping gas flow rate and MgO catalyst

Cotton seed, as a biomass source, is pyrolysed in a tubular fixed-bed reactor under various sweeping gas (N₂) flow rates at different pyrolysis temperatures. In the non-catalytic work, the maximum bio-oil yield was attained as 48.30% at 550 °C with a sweeping gas flow rate of 200 mL min⁻¹. At the optimum conditions, catalytic pyrolysis of biomass samples was performed with various amounts of MgO catalyst (5, 10, 15, and 20 wt.% of raw material). Catalyst addition decreased the quantity of bio-oil yet increased the quality of bio-oil in terms of calorific value, hydrocarbon distribution and removal of oxygenated groups. It was observed that increasing the amount of catalyst used, decreased the oil yields while increased the gas and char yields. Bio-oils obtained at the optimum conditions were separated into aliphatic, aromatic and polar sub-fractions. After the application of column chromatography, bio-oils were subjected into elemental, FT-IR and ¹H NMR analyses. Aliphatic sub-fractions of bio-oils were analyzed by GC–MS. It was deduced that the fuel obtained via catalytic pyrolysis mainly consisted of lower weight hydrocarbons in the diesel range. Finally, obtained results were compared with petroleum fractions and evaluated as a potential source for liquid fuels.     

内循环串行流化床生物质催化热解试验研究

在处理量为0.2 kg/h的新型内循环串行流化床(IIFB)上进行了生物质催化热解制油的试验研究.以木屑为原料、石英砂为热载体,研究了在没有催化剂条件下反应温度对热解产物分布的影响;以HZSM-5催化剂与石英砂混合物为床料进行了催化热解试验,并对热解产物和反应后的催化剂进行了表征分析.结果表明:反应温度为515℃时,液体产物的收率最高.HZSM-5催化剂的加入促进了气体以及焦炭的生成,使液体产物的收率降低,且催化剂体积分数越大,影响越显著.催化荆表面的积炭经燃烧反应后被除去,催化剂的稳定性得到改善.热解不可冷凝气体的主要成分为CO和CO2,随着热解温度的升高,CO2产量下降,CO和CH4的产量增加.经HZSM-5催化热解后,生物油中的酸、醛和酮类物质含量明显减少,而小分子的烃类与酚类物质含量明显增加,表明催化剂具有明显的脱氧效果.