Upgrading of fast pyrolysis bio-oil to drop-in fuel over Ru catalysts

Catalyst plays a key role in the upgrading of fast pyrolysis bio-oil to advanced drop-in fuel, while the selectivity and deactivation of catalyst still remain the biggest challenge. In this study, three Ru catalysts with activated carbon, Al₂O₃ and ZSM-5 as supports were prepared and tested in bio-oil hydrotreating process. The physical properties and components of upgraded bio-oil were detected to identify the difference in catalytic performance of three catalysts. The results showed that furan, phenols and their derivatives in fast pyrolysis bio-oil could be hydrogenated to alkanes, alkenes and benzenes over Ru catalysts. The different components of oil phase over three catalysts may be resulted from the surface properties of three supports. Activated carbon supported Ru catalyst showed the best catalytic performance and was suggested to be the most promising catalyst for pyrolysis bio-oil upgrading.     

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%.     

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.     

Life cycle greenhouse gas emissions analysis of catalysts for hydrotreating of fast pyrolysis bio-oil

Bio-oil from fast pyrolysis of biomass requires multi-stage catalytic hydroprocessing to produce hydrocarbon drop-in fuels. One process design currently in development involves fixed beds of ruthenium-based catalyst and conventional petroleum hydrotreating catalyst. As the catalyst is spent over time as a result of coking and other deactivation mechanisms, it must be changed out and replaced with fresh catalyst. A main focus of bio-oil upgrading research is increasing catalyst lifetimes to 1 year. Biofuel life cycle greenhouse gas (GHG) assessments typically ignore the impact of catalyst consumed during fuel conversion as a result of limited lifetime, representing a data gap in the analyses. To help fill this data gap, life cycle GHGs were estimated for two representative examples of fast pyrolysis bio-oil hydrotreating catalyst, NiMo/Al₂O₃ and Ru/C, and integrated into the conversion-stage GHG analysis. Life cycle GHGs are estimated at 5.5 kg CO₂-e/kg catalyst for NiMo/Al₂O₃. Results vary significantly for Ru/C, depending on whether economic or mass allocation methods are used. Life cycle GHGs for Ru/C are estimated at 80.4 kg CO₂-e/kg catalyst using economic allocation and 13.7 kg CO₂-e/kg catalyst using mass allocation. Contribution of catalyst consumption to total conversion-stage GHGs at 1-year catalyst lifetimes is 0.5% for NiMo/Al₂O₃ and 5% for Ru/C when economic allocation is used (1% for mass allocation). This analysis does not consider the use of recovered metals from catalysts and other wastes for catalyst manufacture and therefore these are likely to be conservative estimates compared to applications where a spent catalyst recycler can be used.     

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.     

Hydrodeoxygenation of 2-methoxy phenol: Effects of catalysts and process parameters on conversion and products selectivity

The hydrodeoxygenation (HDO) of 2-methoxy phenol (MP), a lignin-derived compound, has massive prospective for valuable compounds production. The lignin derived model compounds can be used for production of green chemicals. The model compound MP conversion into cyclohexane was investigated over Ru metal loaded on various supports (ZSM-5, Y-zeolite, β-zeolite, COK-12, mordenite, ZrO₂, and TiO₂). The catalytic properties such as the acidic sites, pore size, and morphology influenced the HDO activity and selectivity of the cyclohexane. The yield of cyclohexane increases up to optimum acidity further increases the acidity of the catalyst, the product yield decreased. The experiments carried out at temperature range of 200–300 °C, and 1–25 bar hydrogen pressure in a fixed bed reactor. The parameters greatly influenced the HDO as well as the cyclohexane yield, selectivity, and MP conversion. The highest conversion (100%) and yield of cyclohexane (99.0%) observed at 250 °C under pressure of 20 bar with Ru/ZSM-5 catalyst. Further the recyclability and stability have been checked and observed that Ru/ZSM-5 is stable up to 200 h and displayed excellence activity in both HDO and cyclohexane selectivity. Weight hourly space velocity (WHSV) was investigated (0.5–1.5 h⁻¹). The suitable WHSV found for HDO of 2-methoxy phenol and cyclohexane yield was 1 h⁻¹. The reaction mechanism showed that the Ru/ZSM-5 catalyst provoked the HDO compared to the others catalyst.     

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.     

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.     

Upgrading of liquid fuel from the vacuum pyrolysis of biomass over the Mo–Ni/γ-Al2O3 catalysts

High amounts of acid compounds in bio-oil not only lead to the deleterious properties such as corrosiveness and high acidity, but also set up many obstacles to its wide applications. By hydrotreating the bio-oil under mild conditions, some carboxylic acid compounds could be converted to alcohols which would esterify with the unconverted acids in the bio-oil to produce esters. The properties of the bio-oil could be improved by this method. In the paper, the raw bio-oil was produced by vacuum pyrolysis of pine sawdust. The optimal production conditions were investigated. A series of nickel-based catalysts were prepared. Their catalytic activities were evaluated by upgrading of model compound (glacial acetic acid). Results showed that the reduced Mo–10Ni/γ-Al₂O₃ catalyst had the highest activity with the acetic acid conversion of 33.2%. Upgrading of the raw bio-oil was investigated over reduced Mo–10Ni/γ-Al₂O₃ catalyst. After the upgrading process, the pH value of the bio-oil increased from 2.16 to 2.84. The water content increased from 46.2 wt.% to 58.99 wt.%. The H element content in the bio-oil increased from 6.61 wt.% to 6.93 wt.%. The dynamic viscosity decreased a little. The results of GC–MS spectrometry analysis showed that the ester compounds in the upgraded bio-oil increased by 3 times. It is possible to improve the properties of bio-oil by hydrotreating and esterifying carboxyl group compounds in the bio-oil.     

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.     

生物油加氢脱氧催化剂研究进展

石油资源的日趋枯竭及其引起的环境问题,使生物油作为石油替代能源备受关注。然而,生物油中的羧酸含量较高、热稳定性差,是阻碍其规模化应用的主要障碍之一,常需要对其进行加氢脱氧（HDO）提质。本文综述了应用于生物油HDO的几种催化剂类型,主要包括金属催化剂、分子筛载体催化剂、复合碳载体催化剂、多孔有机聚合物载体催化剂和缺陷催化剂等,认为开发出一种具有高催化活性且成本较低的非贵金属催化剂是催化剂工业未来的发展趋势。     

Diameter-controlled carbon nanotubes and hydrogen production

Simultaneous production of hydrogen and carbon nanomaterials over Ni-loaded ZSM-5 catalysts via catalytic decomposition of methane was investigated. The effects of nickel particle size and reaction temperature on the hydrogen production, catalyst deactivation and the morphologies of the carbon nanotubes were investigated. Two catalyst were prepared: Ni/ZSM-5(300) – predominant size of the Ni particles 30–60 nm and nNi/ZSM-5(300) predominant size of the Ni particles 10–20 nm.     

Vapour phase hydrodeoxygenation of furfural into fuel grade compounds on NiPMoS catalyst: Synergetic effect of NiP and laponite support

The goal of the research would be to comprehend synergetic effect, additionally the Ni promotion level in the unsupported and Laponite supported NiMoS & NiPMoS catalysts. In this process, the sulfide catalysts were synthesized by a soft chemical approach under hydrothermal condition and also the Ni promotion was enhanced with the addition of phosphorus. The catalysts were characterized predicated on XRD, N₂–physisorption, TPR, H₂ pulse chemisorption, and XPS analysis. The catalysts were evaluated and compared for HDO of furfural (Hemicellulosic model compound) on temperature ranges from 503 K to 583 K under 20 bar H₂ pressurized reaction condition in the vapour phase reactor. The characterization of phosphorus added NiMoS catalysts exhibited improved textural properties with a suitable surface morphology, extraordinary stability, metal-support interaction, and metal dispersion on the support. The catalytic activity results revealed that the unsupported and Laponite supported NiPMoS catalyst performed better HDO conversion of furfural with remarkable high stability, producing deoxygenated hydrocarbons. Thereby, an innovative new unsupported and Laponite supported NiPMoS catalysts were successfully developed. The synergetic factor, intrinsic rate associated with the catalysts were correlated with improved textural properties, surface morphology, percentage of sulfidation of NiMo species, a large amount of acid sites, and dissociated hydrogen species of the catalysts.     

Hydrothermal depolymerization of alkali lignin to high-yield monomers over nickel nitrate modified commercial hydrotalcites catalyst

The depolymerization of alkali lignin was investigated over several nitrate modified commercially hydrotalcites catalysts via hydrothermal depolymerization strategy in this study. The obtained results demonstrated that nickel nitrate modified hydrotalcites (HTCs) exhibits excellent catalytic performance to dissociation of C–C and C–O bonds linkage of alkali lignin to yield aromatics. The bio-oil yield increased to 87.9% with 5%Ni-rhHTCs as catalysts from 65.3% with rhHTCs as catalysts, and guaiacol and guaiacol derivatives were found to be the main composition and the highest monomers yield of 35.2 wt% was achieved. It was also found that the characteristic structure of HTCs was restored during rehydration and the structure of rhHTCs was not changed during the preparation of catalyst, but the basic site tensity and distribution are evidently influenced by the loaded metal nitrate and thus promised the excellent catalytic performance of the modified catalyst.     

Catalytic pyrolysis of pinewood over ZSM-5 and CaO for aromatic hydrocarbon: Analytical Py-GC/MS study

A higher amount of oxygenates is the main constraint for higher yield and quality of aromatics in catalytic pyrolysis while a study of hydrocarbon production with a balance of reactive species lies importance in the catalytic upgrading of pyrolytic vapor. Catalytic pyrolysis of pinewood sawdust over acidic (ZSM-5) and basic (CaO) catalyst was conducted by means of Py-GC/MS to evaluate the effect of biomass to catalyst loading ratio on aromatic hydrocarbon production. Catalytic pyrolysis with four different biomass to catalyst ratios (0.25:1, 0.5:1, 1:1, and 2:1) and non-catalytic pyrolysis were conducted. It has been obtained that ZSM-5 showed better catalytic activity in terms of a high fraction of aromatic hydrocarbon. The ZSM-5 catalyst showed a potential on the aromatization as the yield of aromatic hydrocarbon was increased with a higher amount of ZSM-5 catalyst and the highest yield of aromatics (42.19 wt %) was observed for biomass to catalyst ratio of 0.25:1. On the other hand, basic CaO catalyst was not selective to aromatic hydrocarbon from pinewood sawdust but explored high deacidification reaction in pyrolytic vapor compared to ZSM-5 catalyst, whereas non-catalytic pyrolysis resulted in acidic species (13.45 wt %) and phenolics (46.5 wt %). Based on the results, ZSM-5 catalyst can only be suggested for catalytic pyrolysis of pinewood sawdust for aromatic hydrocarbon production.     

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.     

Hydrogen production by low-temperature reforming of organic compounds in bio-oil over a CNT-promoting Ni catalyst

Present study reports on high catalytic activity of CNTs-supported Ni catalyst (x% Ni-CNTs) synthesized by the homogeneous deposition–precipitation method, which was successfully applied for low-temperature reforming of organic compounds in bio-oil. The optimal Ni-loading content was about 15 wt%. The H₂ yield over the 15 wt% Ni-CNTs catalyst reached about 92.5% at 550 °C. The influences of the reforming temperature (T), the molar ratio of steam to carbon fed (S/C) and the current (I) passing through the catalyst, on the reforming process of the bio-oil over the Ni-CNTs' catalysts were investigated using the stream as the carrier gas in the reforming reactor. The features of the Ni-CNTs' catalysts with different loading contents of Ni were investigated via XRD, XPS, TEM, ICP/AES, H₂-TPD and the N₂ adsorption–desorption isotherms. From these analyses, it was found that the uniform and narrow distribution with smaller Ni particle size as well as higher Ni dispersion was realized for the CNTs-supported Ni catalyst, leading to excellent low-temperature reforming of oxygenated organic compounds in bio-oil.     

Catalytic steam reforming of bio-oil model compounds for hydrogen production over coal ash supported Ni catalyst

The development of a high performance and low cost catalyst is an important contribution to clean hydrogen production via the catalytic steam reforming of renewable bio-oil. Solid waste coal ash, which contains SiO₂, Al₂O₃, Fe₂O₃ and many alkali and alkaline earth metal oxides, was selected as a superior support for a Ni-based catalyst. The chemical composition and textural structures of the ash and the Ni/Ash catalysts were systematically characterized. Acetic acid and phenol were selected as two typical bio-oil model compounds to test the catalyst activity and stability. The conversion of acetic acid and phenol reached as much as 98.4% and 83.5%, respectively, at 700 °C. It is shown that the performance of the Ni/Ash catalyst was comparable with other commercial Ni-based steam reforming catalysts.     

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.     

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.