Effect of heating rate on pyrolysis of low-grade pyrolytic oil

The low-grade pyrolytic oil produced from pyrolysis of municipal plastic waste in a commercial rotary kiln reaction system cannot be an acceptable fuel oil due to its low quality. Thus, the degradation of pyrolytic oil was conducted in a bench scale batch reactor, which was done by two experiment conditions of high heating rate (about 7 °C/min) and low heating rate (1.5–3.6 °C/min) up to 420 °C of reaction temperature. The characteristics of raw pyrolytic oil were examined and also the characteristics of products obtained by different heating rates were compared. Raw pyrolytic oil had higher H/C ratio and higher heating value than commercial oils, and also its peak range in GC analysis showed wide distribution including all the range of gasoline, kerosene and diesel. In the upgrading of pyrolytic oil, cumulative amount profile of product oil, as a function of reaction time, was similar in shape to the degradation temperature profile. All product oils obtained by different degradation temperature had higher H/C ratio and slightly higher heating value than those of raw pyrolytic oil. Also, the characteristics of product oils were influenced by heating rate and reaction temperature.     

Supercritical carbon dioxide extraction of oil from Mexican chia seed (Salvia hispanica L.): Characterization and process optimization

Supercritical carbon dioxide (SC-CO₂) was employed to extract oil rich in omega-3 fatty acids (FAs) from chia seeds, and the physicochemical properties of the oil were determined. A central composite rotatable design was used to analyze the impact of temperature (40 °C, 60 °C and 80 °C), pressure (250 bar, 350 bar and 450 bar) and time (60 min, 150 min and 240 min) on oil extraction yield, and a response surface methodology (RSM) was applied. The extraction time and pressure had the greatest effects on oil. The highest oil yield was 92.8% after 300 min of extraction time at 450 bar. The FA composition varied depending on operating conditions but had a high content of α-linolenic acid (44.4-63.4%) and linoleic acid (19.6-35.0%). The rheological evaluation of the oils indicated a Newtonian behavior. The viscosity of the oil decreased with the increase in temperature following an Arrhenius-type relationship.     

Hydrothermal reforming of bio-diesel plant waste: Products distribution and characterization

A viscous waste derived from a bio-diesel production plant, in the form of crude glycerol, was reacted under subcritical and supercritical water conditions and the product composition determined in relation to process conditions. Preliminary analysis of the original sample showed that the main constituent organic compounds were methanol (20.8 wt.%), glycerol (42.3 wt.%) and fatty acid methyl esters (33.1 wt.%). Uncatalyzed reforming experiments were carried out in a 75 ml Hastelloy-C batch reactor at temperatures between 300 °C and 450 °C and pressures between 8.5 MPa and 31 MPa. Oil/wax constituted more than 62 wt.% of the reactions products. At 300 °C, the main product was a waxy material containing mainly glycerol and fatty acid methyl esters. As the temperature increased to supercritical water conditions, low viscosity oils were produced and all of the glycerol was reacted. The oils contained mainly saturated and unsaturated fatty acid esters as well as their decomposition products. The gaseous products were carbon dioxide, hydrogen and methane and lower concentrations of carbon monoxide and C₂-C₄ hydrocarbons. No char formation was observed. However, during alkaline gasification with sodium hydroxide at 380 °C, the reaction products included a gaseous effluent containing up to 90% by volume of hydrogen, in addition to oil and significant amount of whitish solid residue (soap). Sodium hydroxide influenced the production of hydrogen via water-gas shift by the removal of carbon dioxide as sodium carbonate, but also decreased oil product possibly through saponification.     

Metal-ion pillared clays as hydrocracking catalysts (I): Catalyst preparation and assessment of performance at short contact times

A set of pillared clay catalysts based on montmorillonite (a natural clay) and laponite (a synthetic clay) have been prepared. The new catalysts have been pillared with tin, chromium and aluminium pillars as well as layered double hydroxides based on polyoxo-vanadate and -molybdate. The activities of these novel catalysts have been compared with that of a commercial supported NiMo/Al₂O₃ catalyst and with sulphided Mo(CO)₆ during short (10 min) contact runs. A coal extract sample was reacted at 440 °C in a microbomb reactor in the presence of tetralin and 19 MPa hydrogen. Products were compared by size exclusion chromatography, using NMP as eluent, and by UV-fluorescence. Boiling point distributions of hydrocracked products were determined by a TGA based method; ‘conversions’ were defined as the decrease in the fraction of material with boiling points >450 °C during the reaction. Previous work at 440 °C and 19 MPa H₂ indicates extensive thermal (pyrolytic) cracking during the first 10 min; in the absence of catalyst recombination reactions rapidly take over. Results with several of the new catalysts did not show any improvement compared to the absence of catalyst with ∼39% conversion. The highest conversion (∼70%) was obtained with the Sn laponite pillared clay. The Cr montmorillonite catalyst, pre-calcined at 500 °C, gave the greatest overall shift to smaller molecular masses even though the observed conversion of >450 °C boiling material was relatively poor.     

Production of pyrolytic oils by catalytic pyrolysis of Malaysian refuse-derived fuels in continuously stirred batch reactor

Malaysian refuse derived fuels (RDF) as valuable fraction of waste recycling were pyrolyzed in continuously stirred batch rig at 450 °C in the presence and absence of catalysts. Different types of catalysts were used for upgrading both quantity and quality of pyrolysis products: Y-zeolite, equilibrium FCC, ZSM-5, Ni-Mo-catalyst, Co-Mo-catalyst, silica-alumina and alumina. Gas-chromatography, Fourier-transformed infrared spectroscopy, X-ray spectroscopy and other standardized methods were used for the identification of product. RDF pyrolysis has produced gases with yields of 15.7-27.8%, pyrolytic oils of 9.8-17.8% and water (9.2-12.8%) depending on the types of applied catalyst. Data showed that the volatile fraction (both gas and pyrolytic oils) slightly increased with the catalyst, especially for Y-zeolite and ZSM-5. Gases consisted of CO, CO₂, hydrogen and hydrocarbons. Main chemical compounds, such as aromatic, branched and non-branched in pyrolytic oils have been affected by catalysts, e.g. isomerization of main carbon frame and aromatization have been shown increasing in yields especially when Y-zeolite and ZSM-5 were applied. The phenol, benzene 1,3-diol and methyl-phenol content of pyrolytic oil obtained from non-catalytic pyrolysis decreased at 45.0%, 40.9% and 38.0%, respectively in the presence of Y-zeolite and at 39.4%, 36.9% and 26.9% over Co-Mo-catalyst compared to the catalyst free pyrolysis, respectively. Sulphur, nitrogen and chlorine were found as contaminants in pyrolytic oils, but their contaminants concentration could be significantly decreased by the use of catalysts. The activity of catalysts in the decrease of impurity followed the order of Ni-Mo-cat. > Co-Mo-cat. > Y-zeolite > FCC > ZSM-5 > Al₂O₃/SiO₂ > Al₂O₃. According to EDXRFS analysis, char consisted of impurities such as Ca, Ti, Fe, Cu, Zn and Pb elements.     

Pyrolysis of a fraction of waste polypropylene and polyethylene for the recovery of BTX aromatics using a fluidized bed reactor

Fractions of waste polypropylene and polyethylene were pyrolyzed in a pyrolysis plant under different conditions. In this study, the influence of the reaction temperature (650-750 °C), the feed rate, and the kind of fluidizing medium on the product spectrum were investigated. Pyrolysis of the PP fraction produced oils up to 43 wt. % of the product. With respect to the PE fraction, the maximum oil yield was above 60 wt. % of the product. The target compound was BTX aromatics, whose amount in the oils reached 53 wt.% for the PP fraction and 32 wt. % for the PE fraction. It was shown that the PE fraction yielded a higher liquid product compared to the PP fraction, and that the concentration of aromatics in the oil increased at higher reaction temperatures for both the PP and PE fractions. A higher feed rate and the use of a gas product as the fluidizing medium were favored for the production of oils for both the PP and PE fractions. The oils that were obtained in the experiments almost had no metal and chlorine contents. The maximum heating value of the gas obtained in the experiments was about 50 MJ/kg.     

Pyrolysis of mixed plastics for the recovery of useful products

Thermal and catalytic pyrolysis of polystyrene (PS) with low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), poly-ethylene terephthalate (PET) plastics were carried out in a 25 cm³ stainless steel micro reactor at around 430–440 °C under 5.5–6.0 MPa of N₂ gas pressure for 1 h. Three reactions of each plastic with PS were conducted in the ratio of 1:1, 1:2 and 1:3. The amount of PS was varied to explore its role and reactivity. In all coprocessing reactions, ratio 1:1 afforded the best yields in the form pyrolytic oils. SIM distillation of hexane soluble portion showed that the low boiling fractions were not found and fractions were obtained only after 96 °C + boiling point. It could be due to the vaporization of high volatile components. In most of the binary pyrolysis, light cycle oil (LCO) fractions have low recovery than heavy cycle oil (HCO). GC identified some very important chemical compounds present in the liquid products obtained from the pyrolysis of mixed plastics. The results obtained from this study have shown usefulness and feasibility of the pyrolysis process of the mixed plastics as an alternative approach to feedstock recycling.     

Alkyd resins synthesized from postconsumer PET bottles

Simultaneous glycolysis and neutral hydrolysis of waste PET flakes obtained from grinding postconsumer bottles was carried out in the presence of xylene and an emulsifier at 180 °C. The product was separated from EG, water and xylene by filtration and was extracted by water at boiling point three times. The remaining solid was named water insoluble fraction (WIF). The filtrate was cooled to 4 °C and the crystallized solid obtained by filtration was named water-soluble crystallizable fraction (WSCF). These fractions were characterized by acid value (AV), hydroxyl value (HV) determinations. WSCF and WIF were used for preparation of the alkyd resins. Three long oil alkyd resins were prepared from phthalic anhydride (PA) (reference alkyd resin) or depolymerization product of the waste PET (PET-based alkyd resin), glycerin (G), sunflower oil fatty acids (SOFA) and glycol (EG) (reference alkyd resin) or depolymerization product of the waste PET (PET-based alkyd resin). Film properties and thermal degradation stabilities of these alkyd resins were investigated. Physical properties (drying times, hardness and abrasion resistance) and thermal degradation stabilities of the PET-based alkyd resins are better than these properties of the reference alkyd resin.     

Thermal stability of biodiesel in supercritical methanol

Non-catalytic biodiesel production technologies from oils/fats in plants and animals have been developed in our laboratory employing supercritical methanol. Due to conditions in high temperature and high pressure of the supercritical fluid, thermal stability of fatty acid methyl esters and actual biodiesel prepared from various plant oils was studied in supercritical methanol over a range of its condition between 270 °C/17 MPa and 380 °C/56 MPa. In addition, the effect of thermal degradation on cold flow properties was studied. As a result, it was found that all fatty acid methyl esters including poly-unsaturated ones were stable at 270 °C/17 MPa, but at 350 °C/43 MPa, they were partly decomposed to reduce the yield with isomerization from cis-type to trans-type. These behaviors were also observed for actual biodiesel prepared from linseed oil, safflower oil, which are high in poly-unsaturated fatty acids. Cold flow properties of actual biodiesel, however, remained almost unchanged after supercritical methanol exposure at 270 °C/17 MPa and 350 °C/43 MPa. For the latter condition, however, poly-unsaturated fatty acids were sacrificed to be decomposed and reduced in yield. From these results, it was clarified that reaction temperature in supercritical methanol process should be lower than 300 °C, preferably 270 °C with a supercritical pressure higher than 8.09 MPa, in terms of thermal stabilization for high-quality biodiesel production.     

Hydrocracking of petroleum vacuum distillate containing rapeseed oil: Evaluation of diesel fuel

Hydrocracking of pure petroleum vacuum distillate and the same fraction containing 5 wt.% of rapeseed oil was carried out at 400 and 420 °C and under a hydrogen pressure of 18 MPa over commercial Ni-Mo catalyst. Reaction products were separated by distillation into kerosene, gas oil and the residue. Fuel properties of fractions suitable for diesel production were evaluated (gas oils and remixed blends of kerosene and gas oil). Gas oils obtained from co-processing showed very good fuel properties as the remixed distillates did. Gas oil obtained from co-processing at 420 °C showed also reasonable key low-temperature properties (cloud point: −23 °C, CFPP: −24 °C) similar to those of gas oil obtained from pure petroleum raw material processing.     

Catalytic degradation of waste high-density polyethylene into fuel products using BaCO3 as a catalyst

Waste high-density polyethylene (HDPE) was degraded thermally and catalytically using BaCO₃ as a catalyst under different conditions of temperature, cat/pol ratio and time. The oil collected at optimum conditions (450 °C, 0.1 cat/pol ratio and 2 h reaction time) was fractionated at different temperatures and fuel property of the fractions and parent oil was evaluated by their physicochemical parameters for fuel tests. The results were compared with the standard values for gasoline, kerosene and diesel oil. Boiling point distribution (BPD) curves were plotted from the gas chromatographic study of the samples and compared with that of the standard gasoline, kerosene and diesel. The oil samples were analyzed using GC/MS in order to find out their composition. The physical parameters and the composition of the parent oil and its fractions support the resemblance of the samples with the standard fuel oils. The light fractions best match with gasoline, the middle fractions match with kerosene and the heavier fractions match with diesel oil in almost all of the characteristic properties.     

Prospects of non-catalytic supercritical methyl acetate process in biodiesel production

Conventional biodiesel production methods utilize alcohol as acyl acceptor and produces glycerol as side product. Hence, with escalating production of biodiesel throughout the world, it leads to oversupply of glycerol and subsequently causes devaluation in the market. In this study, methyl acetate was employed as acyl acceptor in non-catalytic supercritical methyl acetate (SCMA) process to produce fatty acid methyl esters (FAME) and side product of triacetin, a valuable fuel additive instead of glycerol. Consequently, the properties of biodiesel produced (FAME and triacetin) are superior compared to conventional biodiesel method (FAME only). In this research, the effects of reaction temperature, reaction time and molar ratio of methyl acetate to oil on the yield of biodiesel were investigated. Apart from that, the influence of impurities commonly found in waste oils/fats such as free fatty acids and water were studied as well and compared with methanol-based reactions of supercritical and heterogeneous catalysis. Results show that biodiesel yields in SCMA process could achieve 99 wt.% when the operating conditions were fixed at 400 °C/220 bar for reaction temperature, methyl acetate/oil molar ratio of 30:1 and 60 min of reaction time. Furthermore, SCMA did not suffer from adverse effect with the presence of impurities, proving that SCMA has a high tolerance towards contamination which is crucial to allow the utilization of inexpensive waste oils/fats as biodiesel feedstock.     

Premium quality renewable diesel fuel by hydroprocessing of sunflower oil

Hydroprocessing of neat sunflower oil was carried out at 360-420 °C and 18 MPa over a commercial hydrocracking catalyst in a bench scale fixed bed reactor. In the studied experimental range, products consisted exclusively of hydrocarbons that differed significantly in composition. While the concentration of n-alkanes exceeded 67 wt.% in the reaction products collected at 360 °C, it decreased to just 20 wt.% in the product obtained at 420 °C. Consequently, the fuel properties of the latter product were very similar to those of standard (petroleum-derived) diesel fuel. Particularly, it exhibited excellent low-temperature properties (cloud point −11 °C; CFPP −14 °C). Reaction products obtained at 400 and 420 °C were blended into petroleum-derived diesel fuel in three concentration levels ranging from 10 to 50 wt.% and the fuel properties of these mixtures were evaluated. Diesel fuel mixtures containing the product of sunflower oil hydrocracking at 420 °C showed very good low-temperature properties including cloud point (−8 °C) and CFPP (−15 °C) that was further lowered to −25 °C due to addition of flow improvers.     

Effect of supercritical water on upgrading reaction of oil sand bitumen

The advantages of supercritical water (SCW) as a reaction medium for upgrading oil sand bitumen were investigated through a comprehensive analysis of the output product, which includes gaseous products, middle distillate, distillation residue, and coke. Canadian oil sand bitumen mined by the steam assisted gravity drainage method was treated in an autoclave at 420-450 °C and 20-30 MPa for up to 120 min with three kinds of reaction media: SCW, high-pressure nitrogen, and supercritical toluene. The yields of gaseous products indicated that a very small amount of water was involved in the upgrading reaction. The analytical results of the middle distillate fractions were almost the same using water and nitrogen at 450 °C. The distillation residues produced in SCW had lower molecular weight distributions, lower H/C atomic ratios, higher aromaticities, and consequently more condensed structures compared to those produced in nitrogen. The coke produced using SCW also had lower H/C values and higher aromaticities. Judging from all the analytical results, the upgrading of bitumen by SCW reaction was primarily considered to be physical in nature. As a result, it is possible to highly disperse the heavy fractions by SCW. This dispersion effect of SCW led to intramolecular dehydrogenation of the heavier component and prevention of recombination reactions, and consequently gave the highest conversion.     

Copyrolysis of oils/waxes of individual and mixed polyalkenes cracking products with petroleum fraction

Copyrolysis of 10 mass% solutions (oils/waxes from individual or mixed polymers with heavy naphtha) is a route for treatment of plastic waste. Linear low-density polyethylene (LLDPE), mixture of high-density polyethylene/low-density polyethylene/linear low-density polyethylene/polypropylene (HDPE/LDPE/LLDPE/PP = 1:1:1:1mass) and linear low-density polyethylene/low-density polyethylene/polypropylene/high-density polyethylene/polyvinyl chloride/polyethylene terepthalate/polystyrene (LLDPE/LDPE/PP/HDPE/PVC/PET/PS = 1:1:2:2:0.05:0.05:0.156 mass) were converted to oils/waxes, gases and solid residues by thermal decomposition in batch reactor at 450 °C. Oils/waxes were dissolved in virgin heavy naphtha to create the feedstock. The influence of residence time from 0.08 to 0.51 s at temperatures 780 °C and 820 °C on product distribution during the copyrolysis was studied. The yields obtained from gaseous and liquid products of solutions are compared to the yields obtained from virgin heavy naphtha. It was studied how addition of the oil/wax influences formation of C₂ and C₃ hydrocarbons (mainly ethene and propene) and aromatics in comparison to the virgin heavy naphtha. The ethene and propene yields from copyrolysis of solutions are comparable or higher than from virgin heavy naphtha. Copyrolysis of solution LLDPE/LDPE/PP/HDPE/PVC/PET/PS gives the maximum yields of propene from all studied oils/waxes. The result suggests that oils/waxes from polymers are suitable feedstocks for copyrolysis with virgin heavy naphtha.     

Use of methanol and oxygen in promoting the destruction of deca-chlorobiphenyl in supercritical water

The destruction of the well-known PCB, deca-chlorobiphenyl (10-CB), by oxidation and methanolysis in supercritical water (SCW), has been studied in a micro-reactor hydrothermal diamond-anvil cell (DAC, 50 nL) and in larger batch reactors (6 mL). The DAC was coupled to optical and infrared microscopes. In the DAC experiments, 10-CB proved to be stable under pyrolytic conditions, whereas in water, it was hydrolyzed and actually dissolved at temperatures above 475 °C. When partial oxygen was added to the 10-CB/water system, the solubility of 10-CB increased slightly as compared to the pure water experiments, and 10-CB was further decomposed by oxidation. The addition of methanol resulted in further decomposition by methanolysis, as confirmed by FT-IR spectroscopy, and lowered the dissolution temperature to 419 °C. Both oxygen and methanol (25 vol.%) were then used to destroy 10-CB in batch reactors, in which the supercritical water experiments permitted a detailed study of the reaction products of the 10-CB destruction. In the absence of methanol, more than 12 intermediate products were detected by GC-MS, and 99.2% of the 10-CB was destroyed in the presence of 225% excess oxygen at 450 °C within 20 min. When methanol was used in the absence of any excess oxygen, a destruction rate of 100% was achieved at 450 °C within 10 min and only three intermediate products were detected. The enhanced destruction of 10-CB in the presence of methanol is attributed to the homogenous reaction conditions employed and the generation of free radicals.     

Degradation of waste High-density polyethylene into fuel oil using basic catalyst

High-density polyethylene (HDPE) has been degraded thermally and catalytically using MgCO₃ at 450 °C into liquid fraction in a batch reactor. Different conditions like temperature, time and catalyst ratio were optimized for the maximum conversion of HDPE into liquid fraction. Catalytic degradation yielded 92% liquid fraction whereas 90% wax was obtained with thermal degradation. The composition of the liquid fraction was characterized by physicochemical properties of petroleum fuel tests. The catalytic liquid fraction consisted of high concentration of C₈-C₉, C₁₃-C₁₄ and C₁₇-C₁₈ hydrocarbons. The distillation data showed that ∼50% of the fraction has boiling point in the range of gasoline and ∼50% in the range of diesel oil.     

Application of HIGEE process intensification technology in synthesis of petroleum sulfonate surfactant

Petroleum sulfonate (PS) surfactant used for enhanced oil recovery was synthesized by dilute liquid sulfur trioxide and petroleum fraction (PF) of Shengli crude oil as raw materials with the application of HIGEE process intensification technology. The effects of various experimental conditions on the content of active matter and unsulfonated oil were investigated. The optimum conditions were selected as solvent/oil mass ratio 0.5, SO₃/oil mass ratio 0.525, reaction temperature 30 °C, rotating speed 1200 rpm, circulation ratio 4, reaction time 15 min and aging time 50 min under which the active matter content was up to 45.3 wt.% and the oil/water interfacial tension was as low as 4.5 × 10⁻³ mN/m. The higher product quality and higher process efficiency of this new technology is proven by a comparison with traditional STR process.     

Compositional analysis of deasphalted oil before and after hydrocracking over zeolite catalyst by Fourier transform ion cyclotron resonance mass spectrometry

Elemental compositions of components in feed and catalytically processed deasphalted oils were characterized by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The processed oils which were hydrocracked over a zeolite catalyst at three different reaction temperatures (370, 380, and 390 °C) were analyzed. Species of the deasphalted oils were ionized either by electrospray ionization (ESI) or by in-beam electron ionization (EI). The ESI mass spectra were obtained from every feed and processed deasphalted oil. Over 550 chemically different compounds were observed in the feed oil mass spectra. Molecular formulas for the detected peaks were calculated by using accurate mass. The compounds with one N atom as well as one N and S atoms were detected as major and minor component, respectively, in every mass spectrum. The number of the detected species in processed deasphalted oil decreases as the reaction temperature increases. However, the carbon distribution of NS-containing species shifts to high number as the reaction temperature increases. Molecular formulas distribution against Z-value (Z-value is defined as C_nH_2n + ZN_mS_sO_o) and C-number were investigated for the ESI mass spectra. Z-value distribution of the peaks assigned to N-compounds was convergent in its compounds with Z = − 25 as increasing the reaction temperature. Detailed mass spectrum analysis reveals that compounds which were not detected in the feed oil were observed in the mass spectra of processed oils; N, S, and O-containing compounds. For the in-beam EI only the processed oil at 390 °C yields approximately 700 resolved peaks at adopted probe temperature (300 °C) of EI. Molecular formula analysis for the observed peaks was conducted as well as ESI. It reveals that the molecular formulas having Z-value (− 30 < Z < 2) and carbon number ranged from 8 to 31 except for (− 18 < Z < − 12, 15 < C-number < 22) were contained in the processed deasphalted oil. Using complementary ionization techniques to characterize the feed and catalytic reacted deasphalted oils provide better understanding of fuel processing conditions.     

Transesterification of sunflower oil in a countercurrent trickle-bed reactor packed with a CaO catalyst

Transesterification of sunflower oil with methanol to form biodiesel was performed in a countercurrent trickle-bed reactor, using calcium oxide particles 1-2 mm in diameter as a packed, solid base catalyst. Although biodiesel production generally requires a reaction temperature below the boiling point of methanol to maintain a heterogeneous, liquid-liquid reaction, in the present study the reaction temperature was varied from 80 to 140 °C to confirm the progress of transesterification in a gas-liquid-solid phase reaction system. Oil droplets released from a thin tube flowed downward, while vaporized methanol flowed upward in the bed. The effects of the reaction temperature, methanol and oil flow rates, and the bed height on the FAME yield were investigated. The oil residence time in the reactor, which was controlled by changing both the oil flow rate and the bed height, had a significant effect on the FAME yield. In addition, the FAME yield increased with reaction temperature and was maximal at 373 K due to the change in residence time associated with reduced oil viscosity at higher temperatures. The FAME yield was 98% at a reaction temperature of 373 K when the methanol and oil flow rates were 3.8 and 4.1 mL/h, respectively.