Liquefaction of giant fennel (Ferula orientalis L.) in supercritical organic solvents: Effects of liquefaction parameters on product yields and character

Ferula orientalis L. stalks were liquefied in an autoclave in supercritical organic solvents (methanol, ethanol, 2-propanol, acetone and 2-butanol) with (NaOH, Na₂CO₃, ZnCl₂) and without catalyst at five different temperatures ranging from 240 °C to 320 °C. The amounts of solid (unconverted raw material), liquid (bio-oil) and gas produced, as well as the composition of the resulting liquid phase, were determined. The effects of various parameters such as temperature, solvent, catalyst and ratio of catalyst on product yields were investigated. The results showed that conversion highly depends on the temperature and catalyst. The highest bio-oil yield (53.97%) was obtained using acetone with 10% zinc chloride at 300 °C. The liquid products were extracted with benzene and diethyl ether. Some of selected liquid products (bio-oils) were analyzed by elemental, FT-IR and GC–MS. 126 different compounds were identified by GC–MS in the liquid products obtained in ethanol at 300 °C.     

Bio-oil production from Glycyrrhiza glabra through supercritical fluid extraction

Glycyrrhiza glabra was liquefied by ethanol and acetone in an autoclave under high pressure using potassium hydroxide or sodium carbonate as the catalyst, as well as without catalyst at various temperatures (250, 270 and 290 °C) for producing bio-oil. The experimental results show that the yield of the main liquefaction product (bio-oil) was influenced significantly by liquefaction parameters such as solvent type, and catalyst type and temperature. The results showed that the maximum bio-oil yield was obtained in acetone (79%) at 290 °C without catalyst. The products of liquefaction (bio-oil) were analysed and characterized using various methods including elemental analysis, Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry. GC–MS identified 131 and 147 different compounds in the bio-oils obtained at 270 and 290 °C, respectively.     

Pyrolysis of microalgae biomass over carbonate catalysts

Microalgae are seen as potential biomass to be used in a biorefinery concept. Several technologies can be used to convert microalgal biomass, but pyrolysis is viewed as a unique pathway to obtain valuable chemicals distributed in three phases: liquid (bio-oil), gas (bio-gas) and solid (bio-char). The liquid phase, bio-oil, usually presents higher heating value than raw biomass, but acidity and oxygen content are major drawbacks. In situ catalyzed pyrolysis can help to decrease the oxygen content and acidity of pyrolytic bio-oils. Chlorella vulgaris and Scenedesmus obliquus were pyrolyzed in a fixed-bed reactor using commercial carbonate catalysts (Li₂CO₃, Na₂CO₃, K₂CO₃, MgCO₃, SrCO₃ and MnCO₃). The catalysis pyrolysis temperature (375 °C) was selected from thermal degradation profiles obtained using thermogravimetry under nitrogen flow and corresponds to the maximum degradation rate for both microalgae. In spite of similar volatile and fixed carbon contents, microalgae performed differentially during pyrolysis mainly due to the different contents of carbohydrates, oils and proteins. Chlorella vulgaris and Scenedesmus obliquus showed bio-oil yield in the range 26–38 and 28–50 wt%, respectively. Only sodium carbonate was able to decrease the bio-char yield, confirming that carbonate catalysts prompt simultaneously gasification and carbonization reactions. Fourier transform infrared spectra of produced bio-oils showed a net decrease of acidity, associated with carbonyl species when carbonate catalysts were used. Bio-char morphology, for both microalgae, showed evidence of melting and resolidification of cell structures, which might be due to the lower melting points of the pyrolysis products obtained from proteins and lipids. © 2020 Society of Chemical Industry     

PRODUCTION OF BIOFUEL FROM SOFT SHELL OF PISTACHIO (PISTACIA VERA L.)

Soft shell of pistachio (Pistacia vera L.) pyrolysis experiments were performed in a fixed-bed reactor to produce bio-oil. The effects of temperature, heating rate, and sweep gas (N₂) flow rates on the yields and compositions of products were investigated. Pyrolysis runs were performed using reactor temperatures between 350° and 500°C with heating rates of 15° and 50°C/min. Nitrogen flow rates varied between 50 and 200 cm³/min and mean particle size was 0.8 mm. The maximum bio-oil yield of 33.18% was obtained in a nitrogen atmosphere with nitrogen flow rate of 150 cm³/min and at 450°C pyrolysis temperature with a heating rate of 50°C/min.The elemental analysis and gross heating value of the bio-oil were determined, and then the chemical composition of the bio-oil was investigated using chromatographic and spectroscopic techniques. The chemical characterization has shown that the bio-oil obtained from soft shell of pistachio can be used as a renewable fuel and chemical feedstock.     

Catalytic Pyrolysis of Pine Wood Sawdust to Produce Bio-oil: Effect of Temperature and Catalyst Additives

In this work, non-catalytic pyrolysis of Turkish pine (Pinus brutia Ten.) wood sawdust was performed in a fixed-bed reactor at various temperatures to obtain the optimum conditions to achieve a maximum bio-oil yield. The highest yield of bio-oil was obtained about 46 wt% at 550°C for non-catalytic pyrolysis. At the optimum conditions, the effects of different catalyst types (KOH, ZnCl₂, and ZnO) and amount of catalyst (5, 10, 15, and 20 wt%) on the pyrolysis product yields and bio-oil properties were investigated. The presence of catalysts changed the product distribution considerably. Increasing the amount of catalyst led to a decrease in the yield of liquid product, while the gas and char yields increased compared to non-catalytic pyrolysis. The chemical compositions of bio-oil were determined with GC-MS analyses. It was determined that bio-oils contain a large variety of organic compounds, such as furans, aldehydes, ketones, phenols, acids, benzenes, alcohols, alkanes, and polycyclic aromatic hydrocarbons (PAHs). The catalysis by KOH significantly increased the levels of phenols, while it reduced the formation of acids and aldehydes. ZnCl₂ produced bio-oil with high percentages of aldehydes. Moreover, ZnO reduced the proportion of PAH in the bio-oil. These results demonstrated that bio-oils could improve with a catalyst. Therefore, catalyst selection for high bio-oil quality is crucial in industrial applications.     

Improvement of porous cellulose acetate reverse osmosis membranes by change of casting conditions

The effects of temperature of casting solution in the range ?10° to 15°C, that of casting atmosphere in the range 10° to 30°C, relative humidity of casting atmosphere in the range 35% to 75%, and solvent evaporation period in the range 0.5 to 3 min were studied on shrinkage temperatures, solute separations, and product rates of Loeb-Sourirajan-type cellulose acetate membranes in reverse osmosis experiments. The composition of casting solution used was as follows: cellulose acetate, 17; acetone, 69.2; magnesium perchlorate, 1.45; and water, 12.35 wt-%. Best performance was obtained with membranes cast under the following conditions: temperature of casting solution, 10°C; temperature of casting atmosphere, 30°C; relative humidity of casting atmosphere, 65%; and solvent evaporation period, 1 min. For a 90% level of solute separation, the productivities of the above type of membranes were 22.9, 61.4, and 64.5 gallons/day-ft² at 250, 600, and 1500 psig using 3500 ppm NaCl–H₂O, 5000 ppm NaCl–H₂O, and 28395 ppm NaCl–H₂O feed solutions, respectively. In all cases, the feed flow rates corresponded to a mass transfer coefficient of 45 × 10^?4 cm/sec on the high-pressure side of the membrane. The general specifications of the above type of membranes are given for the operating pressures of 250, 600, and 1500 psig. The effects of the above casting condition variables on the surface pore structure during film formation are discussed.     

Conversion of oil palm trunk into bio-oil via treatment with subcritical water

Subcritical water was applied to produce bio-oil from a 21-year-old abandoned oil palm trunk (OPT). The effects of reaction temperature, time, part of trunk taken, and optimum reaction condition were investigated. Higher heating values (HHVs), CHNS/O elemental and GC-MS analysis were performed to characterize the bio-oil. The subcritical water temperatures were manipulated between 100?°C?and?370?°C with 10?°C intervals and the reaction time was varied between 6?s and 20?min. The maximum yield of bio-oil from subcritical water treatment of top and bottom part of OPT was 0.27 and 0.30?kg/kg-dry OPT, respectively. The optimum reaction time and temperature was 5?min and 330?°C. The highest HHV of the bio-oils derived from the top and bottom part of OPT was 33.2?MJ/kg and 26.4?MJ/kg, respectively. From GC-MS measurement, the bio-oil contained phenolic compounds. The bio-oil derived from OPT obtained from subcritical water treatment had high HHV and comparable to other liquid fuels.     

Design, Synthesis, and Catalytic Properties of Silica-Supported, Pt-Promoted Iron Fischer–Tropsch Catalysts

Silica-supported iron catalysts (Fe/SiO₂, FePt/SiO₂, and FePtK/SiO₂) were prepared using a novel nonaqueous (acetone) evaporative deposition technique. This preparation leads to relatively well-dispersed iron phases at modest (10%) metal loadings. Moreover, catalytic activities of these catalysts for Fischer–Tropsch synthesis are high and comparable to industrially relevant precipitated iron catalysts. Catalyst activities were tested following a nonregular L18 orthogonal array that enabled the number of 150-h activity tests to be reduced from 54 to 18; this statistical design was augmented with five additional runs to provide replication. Primary independent variables affecting catalysts' activity were promoter type, pretreatment gas composition (H₂, H₂/CO, or CO), pretreatment temperature (250, 280, or 320 °C), and reaction temperature (250 or 265 °C); iron carbide level measured from Mössbauer spectroscopy was correlated with activity in a separate analysis. Activity was found to increase in the order Fe/SiO₂, FePt/SiO₂, and FePtK/SiO₂. For a given catalyst composition, activity increases to a maximum with increasing pretreatment temperature and increasing time. Catalyst activity was also positively correlated with increasing chi-carbide content for Fe/SiO₂ and FePt/SiO₂ catalysts but not for FePtK/SiO₂. While pretreatment atmosphere greatly influences initial activity–time behavior, activity is less dependent on pretreatment after about 150 h of reaction. Steady-state methane and C₂₊ hydrocarbon selectivities (CO₂-free basis) for the FePtK/SiO₂ catalyst at 250–265 °C, 10 atm, and H₂/CO = 1 are 7–9 and 91–93%, respectively, while its hydrocarbon productivity at 250 °C (normalized to 15 atm, H₂/CO = 0.7) of 0.27 g HC/g_cat/h is comparable to those reported for unsupported precipitated iron catalysts of high activity and selectivity. These results indicate that preparation of an active, selective, stable, attrition-resistant supported iron catalyst for Fischer–Tropsch synthesis is feasible. Promise for additional improvements in catalyst performance through application of advanced preparation methods and optimization of catalyst chemical and physical properties is also indicated.     

Synthesis of phenolic resol resins using cornstalk-derived bio-oil produced by direct liquefaction in hot-compressed phenol–water

For the synthesis of biomass-based resol resins, cornstalk powders were liquefied in a hot-compressed phenol–water (1:4, wt./wt.) medium at 300–350 °C. It was observed that essentially no phenol was reacted with the cornstalk degradation intermediates during the liquefaction process. The cornstalk-derived bio-oils contained oligomers of phenol and substituted phenols, originated primarily from the lignin component of the cornstalk feedstock. Using the cornstalk-derived bio-oils, resol resins were readily synthesized under the catalysis of sodium hydroxide. The biomass-derived resol resins were brown viscous liquids, possessing broad molecular weight distributions. In comparison with those of a conventional phenol resol resin, the properties of the bio-based resins were characterized by GPC, FTIR, DSC and TGA. The as-synthesized bio-oil resol resin exhibited typical properties of a thermosetting phenol–formaldehyde resin, e.g., exothermic curing temperatures at about 150–160 °C, and an acceptable residual carbon yield of ca 56% at 700 °C for the cured material.     

Biomass to hydrogen via catalytic steam reforming of bio-oil over Ni-supported alumina catalysts

Production of hydrogen (H₂) from catalytic steam reforming of bio-oil was investigated in a fixed bed tubular flow reactor over nickel/alumina (Ni/Al₂O₃) supported catalysts at different conditions. The features of the steam reforming of bio-oil, including the effects of metal content, reaction temperature, W_bHSV (defined as the mass flow rate of bio-oil per mass of catalyst) and S/C ratio (the molar ratio of steam to carbon fed) on the hydrogen yield were investigated. Carbon conversion (moles of carbon in the outlet gases to moles of the carbon feed) was also studied, and the outlet gas distributions were obtained. It was revealed that the Al₂O₃ with 14.1% Ni content gave the highest yield of hydrogen (73%) among the catalysts tested, and the best carbon conversion was 79% under the steam reforming conditions of S/C = 5, W_bHSV = 13 1/h and temperature = 950 °C. The H₂ yield increased with increasing temperature and decreasing W_bHSV; whereas the effect of the S/C ratio was less pronounced. In the S/C ratio range of 1 to 2, the hydrogen yield was slightly increased, but when the S/C ratio was increased further, it did not have an effect on the H₂ production yield.     

Production of H2 and medium Btu gas via pyrolysis of lignins in a fixed-bed reactor

Lignins are generally used as a low-grade fuel in the pulp and paper industry. In this work, pyrolysis of Alcell and Kraft lignins obtained from Alcell process and Westvaco, respectively, was carried out in a fixed-bed reactor to produce hydrogen and gas with medium heating value. The effects of carrier gas (helium) flow rate (13.4–33 ml/min/g of lignin), heating rate (5–15°C/min) and temperature (350–800°C) on the lignin conversion, product composition, and gas yield have been studied. The gaseous products mainly consisted of H₂, CO, CO₂, CH₄ and C₂₊. The carrier gas flow rate did not have any significant effect on the conversion. However, at 800°C and at a constant heating rate of 15°C/min with increase in carrier gas flow rate from 13.4 to 33 ml/min/g of lignin, the volume of product gas decreased from 820 to 736 ml/g for Kraft and from 820 to 762 ml/g for Alcell lignin and the production of hydrogen increased from 43 to 66 mol% for Kraft lignin and from 31 to 46 mol% for Alcell lignin. At a lower carrier gas flow rate of 13.4 ml/min/g of lignin, the gas had a maximum heating value of 437 Btu/scf. At this flow rate and at 800°C, with increase in heating rate from 5 to 15°C/min both lignin conversion and hydrogen production increased from 56 to 65 wt.% and 24 to 31 mol%, respectively, for Alcell lignin. With decrease in temperature from 800°C to 350°C, the conversion of Alcell and Kraft lignins were decreased from 65 to 28 wt.% and from 57 to 25 wt.%, respectively. Also, with decrease in temperature, production of hydrogen was decreased. Maximum heating value of gas (491 Btu/scf) was obtained at 450°C for Alcell lignin.     

NiFe/γ-Al2O3: A universal catalyst for the hydrodeoxygenation of bio-oil and its model compounds

NiFe bimetallic catalyst shows an excellent activity and selectivity for the hydrodeoxygenation (HDO) of three typical model compounds of bio-oil. The conversion of furfuryl alcohol, benzene alcohol and ethyl oenanthate is 100, 95.48 and 97.89% at 400 °C and the yield to 2-methylfuran, toluene and heptane is 98.85, 93.49 and 96.11% at 0.1 ml/min flow speed and atmospheric pressure. It indicates that the major reaction pathway is the cleavage of C–O rather than C–C. After the catalytic HDO of bio-oil over NiFe/Al₂O₃ catalyst, the heating value changes from 37.8 to 43.9 MJ/kg, the pH changes from 6.65 to 7.50.     

Pretreatment of barley husk for bioethanol production

This paper reports on the optimization of steam pretreatment of barley husk for high pentose and hexose recovery in the subsequent enzymatic hydrolysis step, as well as high ethanol yield, following simultaneous saccharification and fermentation. The parameters optimized in the steam pretreatment step were residence time (5–15 min), temperature (190–215 °C), and concentration of the acid catalyst (0 or 0.5% H₂SO₄). A microwave oven was employed for screening of the optimal conditions to obtain the highest sugar yield following combined pretreatment and enzymatic hydrolysis. The final optimization of the pretreatment prior to enzymatic hydrolysis was performed on a larger scale, in a steam pretreatment unit. Simultaneous saccharification and fermentation was carried out following steam pretreatment on 5 and 10% dry matter steam‐pretreated slurries. Fermentability tests were performed to determine the effect of by‐products (ie furfural and 5‐hydroxymethyl furfural) in the bioconversion of glucose to ethanol by baker's yeast. The maximum glucose yield, 88% of the theoretical, was obtained following steam pretreatment with 0.5% H₂SO₄ at 200 °C for 10 min. Under these conditions, a sugar to ethanol conversion of 81% was attained in simultaneous saccharification and fermentation. Copyright © 2004 Society of Chemical Industry     

Conversion of oils to monoglycerides by glycerolysis in supercritical carbon dioxide media

Glycerolysis of soybean oil was conducted in a supercritical carbon dioxide (SC-CO₂) atmosphere to produce monoglycerides (MG) in a stirred autoclave at 150–250°C, over a pressure range of 20.7–62.1 MPa, at glycerol/oil molar ratios between 15–25, and water concentrations of 0–8% (wt% of glycerol). MG, di-, triglyceride, and free fatty acid (FFA) composition of the reaction mixture as a function of time was analyzed by supercritical fluid chromatography. Glycerolysis did not occur at 150°C but proceeded to a limited extent at 200°C within 4 h reaction time; however, it did proceed rapidly at 250°C. At 250°C, MG formation decreased significantly (P<0.05) with pressure and increased with glycerol/oil ratio and water concentration. A maximum MG content of 49.2% was achieved at 250°C, 20.7 MPa, a glycerol/oil ratio of 25 and 4% water after 4 h. These conditions also resulted in the formation of 14% FFA. Conversions of other oils (peanut, corn, canola, and cottonseed) were also attempted. Soybean and cottonseed oil yielded the highest and lowest conversion to MG, respectively. Conducting this industrially important reaction in SC-CO₂ atmosphere offered numerous advantages, compared to conventional alkalicatalyzed glycerolysis, including elimination of the alkali catalyst, production of a lighter color and less odor, and ease of separation of the CO₂ from the reaction products.     

On the Production of Hydrogen from Bio-Oil: A Representative Study Using Propylene Glycol

In a bio-refinery focused on fast pyrolysis, hydrogen (H₂) producible from reforming of the aqueous fraction of bio-oil with steam can be utilized for upgrading pyrolytic lignin into fuels by hydrotreatment. In this work, propylene glycol (PG) was chosen as a typical compound symbolizing higher polyols in the bio-oil aqueous fraction. Catalytic processing of PG into H₂ at low temperature (T = 500°C) was investigated using several commercial catalysts such as Ni/Al₂O₃, Ru/Al₂O₃, Ru/C, Pt/C, and Pd/C in a laboratory-scale fixed-bed reactor. The efficiencies of the catalysts were presented as selectivity to CO, CO₂, CH₄ and H₂, and PG conversion into gaseous phase. Wide ranges of temperature (300–500°C), W/F_O (18.6–92.9 g h/mol), and S/C ratio (5.6–12.7 mol/mol) were examined using Ni/Al₂O₃. At T = 500°C, H₂ selectivity (73.7%) and PG conversion (66.2%) were maximized using ratios of catalyst mass to molar flow rate of PG (W/F_O) = 18.6 g h/mol and steam to carbon (S/C) = 12.7 (10 wt% PG solution). It was found that Ni/Al₂O₃ demonstrates stable operation for at least 6 h of time-on-stream. Finally, a plausible reaction pathway for PG reforming was proposed.     

The pyrolysis of waste mandarin residue using thermogravimetric analysis and a batch reactor

A study on the pyrolysis of waste mandarin residue, with the aim of producing bio-oil, is reported. To elucidate the thermodynamics and temperature-dependency of the pyrolysis reaction of waste mandarin residue, the activation energy was obtained by thermogravimetric analysis. Mass loss occurred within the temperature range 200–750 °C, and the average activation energy was calculated to be 205.5 kJ/mol. Pyrolysis experiments were performed using a batch reactor, under different conditions, by varying the carrier gas flow rate and temperature. When the carrier gas flow rate was increased from 15 to 30 and finally to 50ml/min, the oil yield slightly increased. Experiments performed within the temperature range 400–800 °C showed the highest oil yield (38.16 wt%) at 500 °C. The moisture content in the bio-oil increased from 35 to 45% as the temperature increased from 400 to 800 °C, which also resulted in reduction of the oxygenates content and increase in the phenolics and aromatics content, indicating that temperature is an important operating parameter influencing the yield and composition of bio-oil.     

Depolymerization of poly-ϵ-caprolactam catalyzed by sodium hydroxide

Depolymerization of poly-?-caprolactam chips was carried out at low pressures (3–15 mm Hg) and elevated temperature (225°–270°C) in the presence of sodium hydroxide as catalyst. The effects of variation of amount of sodium hydroxide, time, temperature, and pressure on ?-caprolactam yield were studied. With increase in alkali content the yield increases linearly, reaching a maximum at 1% (w/w) NaOH and then falls. The yield increases with time of depolymerization up to 4 1/2 hr and then becomes practically constant. Between 240° and 250°C there is a sudden increase in depolymerization rate. Further increase in temperature has very little effect. Decrease in pressure from 15 to 3 mm Hg shows a nine-fold increase in yield. The optimum conditions for the depolymerization were a temperature of 250°C, a pressure of 3 mm Hg, and a time 4 1/2 hr in the presence of 1% NaOH (w/w), which gave a 90.5% yield of ?-caprolactam. Physical properties, IR spectra, and behavior toward polymerization of the recovered monomer indicated the presence of some impurities.     

High performance polymer composites on PEEK reinforced with aluminum oxide

A study on high performance poly(ether‐ether‐ketone) (PEEK) composites prepared by incorporating aluminum oxide (Al₂O₃), 0 to 50 wt % by hot compaction at 15 MPa and 350°C was described. Density, thermogravimetric analysis/differential scanning calorimetry, and scanning electron microscopy (SEM) were employed to evaluate their density, thermal stability, crystallinity, and morphology. Experimental density was found higher than theoretical density, which indicates that composite samples are sound. It was found that the addition of micron sized (< 15 μm) Al₂O₃ increased the peak crystallization temperature by 12°C when compared with neat PEEK with insignificant increase in melting temperature. Half‐time of crystallization is reduced from 2.05 min for the neat PEEK to 1.08 min for PEEK incorporated with 30 wt % Al₂O₃ because of the strong nucleation effect of Al₂O₃. The thermal stability of composites in air atmosphere was increased by 26°C. However, thermal stability in nitrogen atmosphere decreases at lower concentration of Al₂O₃ but increases above 20 wt % of Al₂O₃. Uniform dispersion of Al₂O₃ particles was observed in PEEK polymer matrix by SEM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4623–4631, 2006     

Biodiesel production from Nannochloropsis microalgal biomass-derived oil: An experimental and theoretical study using the RSM-CCD approach

Biodiesel production from Nannochloropsis is investigated in the current study. Based on the extraction studies, the used biomass is composed of 50% saponifiable lipids, which turns this species to a vulnerable feedstock for biodiesel production. It should also be noted that the acidity of the obtained crude bio-oil is higher than 2 mg KOH/g, hence it was attempted to survey the biodiesel production from the obtained oil through the esterification reaction with the aid of response surface methodology (RSM). According to the data, the highest biodiesel yield (99.5%) from the bio-oil is obtained at a reaction temperature of 69°C, a reaction time of 30 min, a methanol to oil molar ratio of 9:1, and an H₂SO₄ concentration of 0.13 wt.%. In the next step, the in-situ extraction and esterification of Nannochloropsis were investigated at the observed optimum reaction conditions. Based on the analysis, biodiesel yield from the dry cell weight of the biomass is considered to be 16%, which accounts for 99% conversion of bio-oil to biodiesel.     

High Efficient Production of Hydrogen from Bio-oil Using Low-temperature Electrochemical Catalytic Reforming Approach Over NiCuZn–Al2O3 Catalyst

High-efficient production of hydrogen from bio-oil was performed by a novel electrochemical catalytic reforming method over the NiCuZn–Al₂O₃ catalyst. The influences of current on the hydrogen yield, carbon conversion and products’ distribution were investigated. Both the hydrogen yield and carbon conversion were remarkably enhanced by the current through the catalyst, reaching nearly complete conversion with a hydrogen yield of 93.5% even at low reforming temperature of 400 °C. The thermal electrons would play important roles in promoting the reforming reactions of the oxygenated-organic compounds in bio-oil, molecular dissociation and the catalyst reduction.