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 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.     

Understanding the pyrolysis behavior of agriculture,forest and aquatic biomass: Products distribution and characterization

Pyrolysis studies on agricultural (rice straw), forest (pine) and aquatic (Ulva lactuca) biomass were carried out in a fixed bed reactor at different temperature range of 300–550 °C. The product distributions and their characterization of products were compared among these biomasses. The maximum liquid product yield 29.4, 57.5 and 25.6 wt% obtained at 400, 500 and 400 °C respectively from rice straw (RS), pine (PN) and Ulva lactuca (UL) biomass. However, the higher conversion was observed in the case of pine wood biomass 77.0% at 550 °C. From the GC-MS analysis, it is observed that RS and PN bio-oil mostly composed of derivatives of phenolic compounds, while UL bio-oil composed of cyclopentenone derivatives compounds. The highest higher heating value (HHV) was found in pine bio-oil 34.8 MJ/kg. Also PN pyrolytic bio-oil had higher boiling point differences compounds. The bio-char analysis showed that the PN bio-char is a carbon rich and porous in nature as compared to the RS and UL bio-char.     

Production of crude bio-oil via direct liquefaction of spent K-Cups

Spent K-Cups were liquefied into crude bio-oil in a water-ethanol co-solvent mixture and reaction conditions were optimized using response surface methodology (RSM) with a central composite design (CCD). The effects of three independent variables on the yield of crude bio-oil were examined, including the reaction temperature (varied from 255 °C to 350 °C), reaction time (varied from 0 min to 25 min) and solvent/feedstock mass ratio (varied from 2:1 to 12:1). The optimum reaction conditions identified were 276 °C, 3 min, and solvent/feedstock mass ratio of 11:1, giving a mass fraction yield of crude bio-oil of 60.0%. The overall carbon recovery at the optimum conditions was 93% in mass fraction. The effects of catalyst addition (NaOH and H₂SO₄) on the yield of crude bio-oil were also investigated under the optimized reaction conditions. The results revealed that the presence of NaOH promoted the decomposition of feedstock and significantly enhanced the bio-oil production and liquefaction efficiency, whereas the addition of H₂SO₄ resulted in a negative impact on the liquefaction process, decreasing the yield of crude bio-oil.     

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 hydropyrolysis of crop straws with different biochemical composition

In this study, four kinds of straws with different biochemical compositions, including soybean straw (SS), peanut straw (PS), rice straw (RS), and corn straw (CS), were subjected to catalytic hydropyrolysis (HyPy) to explore the influence of biochemical composition on the products distribution and properties of the pyrolysis oil. The HyPy reactions were performed at 400 °C for 2 h with added 10 wt% Pd/C and 4 MPa H₂. During the HyPy, hydrogen and catalyst broke the coating structure and hydrogen bond between cellulose (CL) and hemicellulose (HCL), and thus significantly weakened the biochemical composition effect on the yield and elemental composition of the bio-oil. The bio-oil yield varied between 11.75 wt% and 13.05 wt%, and the C, H, N, O, and S content fell into the following ranges of 82.06–85.15 wt%, 9.24–9.61 wt%, 1.18–1.43 wt%, 4.62–7.86 wt%, 45–130 ppm, respectively. Biochemical composition of straw, especially the mass ratio of CL to HCL (m_CL/m_HCL), markedly influenced the molecular composition of the bio-oil. Hydrocarbons (20.15–46.66%) and phenolic compounds (17.01–47.98%) accounted for the vast majority of the identified compounds. SS and PS with higher m_CL/m_HCL (1.92 and 1.80, respectively) tended to produce bio-oils with more aromatics (22.63% and 20.70%, respectively) and fewer phenolic compounds (17.01% and 22.56%, respectively).     

Catalytic hydrotreating of pyro-oil derived from green microalgae spirulina the (Arthrospira) plantensis over NiMo catalysts impregnated over a novel hybrid support

Upgrading of pyrolysis bio-oil by a novel catalytic hydrotreating process, including hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) was found as an effective technical method for the improvement of biofuel characteristics. In this study, for the first time, the performance of a novel meso-microporous composite material, HMS-ZSM-5, as a support on the catalytic activity of NiMo-based catalysts in the bio-oil hydrotreating was evaluated. The experiments were carried out in a flow fixed-bed reactor at the temperature range of 300–360 °C, 30 bar pressure, and LHSV = 4 h-1. Also, the results were and compared with those of HMS, ZSM-5, and γ-Al2O3 supports. For all catalysts, the increase in temperature resulted in the enhancement of HDO and HDN reactions efficiency. NiMo/HMS-ZSM-5 possessed a high acid property which contributed to the removal of oxygen and nitrogen from bio-oil, with the conversion of 84.10% and 69.60%, respectively. Therefore, the novel catalyst of this study represented much superior upgrading performances compared with those of stand-alone NiMo/HMS and NiMo/ZSM-5 catalysts and also the conventional catalyst of NiMo/γ-Al2O3.     

Highly selective hierarchical ZSM-5 from kaolin for catalytic cracking of Calophyllum inophyllum oil to biofuel

Upgrading the inferior properties of Calophyllum inophyllum oil via catalytic cracking into biofuel required a porous heterogeneous acid catalysts. Hierarchical ZSM-5 (Hi-ZSM-5(K)) produced from desilication of kaolin-derived ZSM-5 was employed as catalyst and the activity was compared with hierarchical ZSM-5 obtained from templating method (Hi-ZSM-5(T)). Catalytic cracking of Calophyllum inophyllum oil was carried out in one-pot reaction at 475 °C for 120 min under the flow of H₂ and the products analysed using GC-MS were consisted of the mixtures of alkane, alkene, oxygenated carbon and aromatics compound. The advantages of desilication method for the formation of highly selective hierarchical ZSM-5 was observed when the catalyst exhibited enhanced acidity with mesopores diameter of 2–5 nm to give 93% conversion and high selectivity towards light C7–C9 hydrocarbons. However, Hi-ZSM-5(T) showed low acidity to give only 43% conversion, and selectivity towards C11–C12 hydrocarbons due to the mesopores diameter of 3–12 nm. The activity of hierarchical ZSM-5 was also compared with microporous ZSM-5 that produced biofuel with approximately equal distribution of C5–C18 hydrocarbons. The role of hierarchical structures was further discussed on the composition of aromatics compound, oxygenates content and alkene/alkane ratios of the biofuel.     

Synthesis of fatty acid methyl esters via the methanolysis of palm oil over Ca3.5xZr0.5yAlxO3 mixed oxide catalyst

Novel mixed metal oxide catalyst Ca_3.5xZr_0.5yAl_xO₃ was synthesized through the coprecipitation of metal hydroxides. The textural, morphological, and surface properties of the synthesized catalysts were characterized via Brunauer–Emmett–Teller method, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. The catalytic performance of the as-synthesized catalyst series was evaluated during the transesterification of cooking palm oil with methanol to produce fatty acid methyl esters (FAME). The influence of different parameters, including the calcination temperature (300–700 °C), methanol to oil molar ratio (6:1–25:1), catalyst amount (0.5–6.5 wt%), reaction time (0.5–12 h) and temperature (70–180 °C), on the process was thoroughly investigated. The metal oxide composite catalyst with a Ca:Zr ratio of 7:1 showed good catalytic activity toward methyl esters. Over 87% of FAME content was obtained when the methanol to oil molar ratio was 12:1, reaction temperature 150 °C, reaction time 5 h and 2.5 wt% of catalyst loading. The catalyst could also be reused for over four cycles.     

Investigating the potential for energy,fuel, materials and chemicals production from corn residues (cobs and stalks) by non-catalytic and catalytic pyrolysis in two reactor configurations

The results of thermogravimetric analysis (TGA), non-catalytic and catalytic pyrolysis of corn cobs and corn stalks are reported in this paper. Pyrolysis took place in two different reactor configurations for both feedstocks: (1) fast pyrolysis in a captive sample reactor; and (2) non-catalytic slow pyrolysis and catalytic pyrolysis in a fixed-bed reactor. Experiments were carried out in atmospheric pressure at three temperatures: low temperature (360–380 °C), medium temperature (500–600 °C) and at high temperature (600–700 °C). The results of the experimental study were compared with data reported in the literature. Investigating the potential of corn residues for energy, fuel, materials and chemicals production according to their thermochemical treatment products yields and quality, it can be stated that: (a) corn stalks could be suitable raw material for energy production via gasification at high temperature, due to their medium low heating value (LHV) of pyrolysis gas (13–15 MJ/m³); (b) corn cob could be a good solid biofuel, due to the high LHV (24–26 MJ/kg) of the produced char; (c) additionally, corn cobs could be a good material for activated carbon production after being activated or gasified with steam, due to its high fixed carbon content(～74 wt%); (d) liquid was the major pyrolysis product from catalytic pyrolysis (about 40–44 wt% on biomass) for both feedstocks; further analysis of the organic phase of the liquid products were hydrocarbons and phenols, which make them interesting for chemicals production.     

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.     

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%.     

Bio-oil production from hydrothermal liquefaction of waste Cyanophyta biomass: Influence of process variables and their interactions on the product distributions

Hydrothermal liquefaction (HTL) of waste Cyanophyta biomass at different temperatures (factor A, 260–420 °C), times (factor B, 5–75 min) and algae/water (a/w) ratios (factor C, 0.02–0.3) by single reaction condition and Response Surface Method (RSM) experiments was investigated. By single reaction condition runs, maximum total bio-oil yield (29.24%) was obtained at 350 °C, 60 min and 0.25 a/w ratio. Maximum bio-oil HHV of 40.04 MJ/kg and energy recovery of 51.09% was achieved at 350 °C, 30 min, 0.1 a/w ratio and 350 °C, 60 min, 0.25 a/w ratio, respectively. RSM results indicate that effect of AB interaction was significant on light bio-oil yield. Both AC and AB had more remarkable influence than BC on heavy bio-oil yield and aqueous total organic carbon (TOC) recovery whereas BC was noticeable on ammonia nitrogen (NH₃N) recovery in aqueous products. By model-based optimization of highest bio-oil yield, the highest bio-oil yield reached 31.79%, increasing by 8.72% after RSM optimization, and light and heavy bio-oil yield was 17.44% and 14.35%, respectively. Long-chain alkanes, alkenes, ketones, fatty acids, phenols, benzenes, amides, naphthalenes were the main components in light bio-oil. Some alcohols, phenols and aromatics were primarily found in heavy bio-oil. Solid residue after HTL consisted of numerous microparticles (～5 μm) observed by Scanning Electron Microscopy (SEM). Energy Dispersive Spectrometer (EDS) analysis shows these particles primarily contained C, O, Mg, P and microelements, derived from Cyanophyta cells.     

Novel core-shell-like Ni-supported hierarchical beta zeolite catalysts on bioethanol steam reforming

Hierarchical-Beta zeolites have been hydrothermally synthesized by adding a new gemini organic surfactant. The used gemini surfactant play the role of a “pore-forming agents” on the mesoscale, on the same time, providing alkaline environment for the system. With this hierarchical Beta zeolite as the core support, we successfully prepared a shell layer of Ni-containing (22 wt%) petal-like core-shell-like catalyst and applied it to bioethanol steam reforming. At the reaction temperature of 350 °C–550 °C, the conversion rate of ethanol and the selectivity of hydrogen were always above 85% and 70%. After reaction of 100 h on stream at 400 °C, there were not obvious inactivation could be observed on NiNPs/OH-MBeta catalyst.     

Hydrothermal liquefaction of spent coffee grounds in water medium for bio-oil production

Spent coffee grounds (SCG) were liquefied in hot-compressed water to produce crude bio-oil via hydrothermal liquefaction (HTL) in a 100 cm³ stainless-steel autoclave reactor in N₂ atmosphere. We investigated the effects of operating parameters such as retention times (5 min, 10 min, 15 min, 20 min and 25 min), reaction temperatures (200 °C, 225 °C, 250 °C, 275 °C and 300 °C), and water/feedstock mass ratios (5:1, 10:1, 15:1 and 20:1) and initial pressure of process gas (2.0 MPa and 0.5 MPa) on the yield and properties of the resulting crude bio-oil. The highest yield of the crude bio-oil (47.3% mass fraction) was obtained at conditions of 275 °C, 10 min retention time and water/feedstock mass ratio of 20:1 with an initial pressure of 2.0 MPa. The elemental analysis of the produced crude bio-oil revealed that the oil product had a higher heating value (HHV) of 31.0 MJ kg⁻¹, much higher than that of the raw material (20.2 MJ kg⁻¹). GC–MS and FT-IR measurements showed that the main volatile compounds in the crude bio-oil were long chain aliphatic acids and esters.     

Comparison of pyrolysis and hydrothermal liquefaction of Chlamydomonas reinhardtii. Growth studies on the recovered hydrothermal aqueous phase

The production of bio-oil by pyrolysis with a high heating rate (500 K s⁻¹) and hydrothermal liquefaction (HTL) of Chlamydomonas reinhardtii was compared. HTL led to bio-oil yield decreasing from 67% mass fraction at 220 °C to 59% mass fraction at 310 °C whereas the bio-oil yield increased from 53% mass fraction at 400 °C to 60% mass fraction at 550 °C for pyrolysis. Energy ratios (energy produced in the form of bio-oil divided by the energy content of the initial microalgae) between 66% at 220 °C and 90% at 310 °C in HTL were obtained whereas it was in the range 73–83% at 400–550 °C for pyrolysis. The Higher Heating Value of the HTL bio-oil was increasing with the temperature while it was constant for pyrolysis. Microalgae cultivation in aqueous phase produced by HTL was also investigated and showed promising results.     

Biodiesel from mutton fat using KOH impregnated MgO as heterogeneous catalysts

The use of MgO impregnated with KOH as heterogeneous catalysts for the transesterification of mutton fat with methanol has been evaluated. The mutton fat (fat) with methanol (1:22 M ratio) at 65 °C showed > 98% conversion to biodiesel with 4 wt% of MgO–KOH-20¹ (MgO impregnated with 20 wt% of KOH) in 20 min. The reaction conditions optimized were; the amount of KOH impregnation (5–20 wt%), the amount of catalyst (1.5–4 wt%, catalyst/fat), the reaction temperature (45–65 °C), fat to methanol molar ratio (1:11–1:22) and the effect of addition of water/oleic acid/palmitic acid (upto 1 wt%). Although, transesterification of fresh fat (moisture content 0.02 wt% and free fatty acids 0.002 wt%) with methanol in the presence of KOH (homogenous catalyst) resulted in the complete conversion to biodiesel, but in the presence of additional 1 wt% of either free fatty acid or moisture content, formation of soap was observed. The MgO–KOH-20 catalyst was found to tolerate additional 1 wt% of either the moisture or FFAs in the fat.     

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.     

Effects of solvents and catalysts in liquefaction of pinewood sawdust for the production of bio-oils

Liquefaction of biomass with proper solvents and catalysts is a promising process to produce liquid biofuels and valuable chemicals. In this study, pinewood sawdust was liquefied in the presence of various supercritical solvents (carbon dioxide, water, acetone, and ethanol) and catalysts (alkali salts and acidic zeolites). The liquid, gas and solid products were analyzed using GC–MS, FT-IR, elemental analyzer, ¹H NMR, ¹³C NMR. The experimental results showed that both solvent and catalyst can significantly improve the liquefaction process by increasing the yield of liquid oil and suppressing the formation of solid residue. K₂CO₃ showed the best performance by doubling the yield of bio oil. Meanwhile, the maximum bio-oil yield (30.8 wt%) and the minimum solid residue yield (28.9 wt%) were obtained when ethanol was employed as the solvent. Solvents can also strongly affect the distribution of liquid products. 2,4,5,7-tetramethyl-phenanthrene and bis(2-ethylhexyl) phthalate were the premier compounds in liquid product as supercritical carbon dioxide is used as solvent while 2-methyl-naphthalene became the main composition when water is used as solvent.