Conversion of plastic waste into fuel oil using zeolite catalysts in a bench-scale pyrolysis reactor

Catalytic pyrolysis of mixed plastic waste to fuel oil experiment was tested with ZSM-5 zeolite (commercial and synthesized) catalysts along with other catalysts. The ZSM-5 zeolite catalyst was effectively produced using a hydrothermal technique via metakaolin as an alumina source. The catalytic pyrolysis of different types of plastic (single and multilayer) wastes in the presence of various catalysts was tested with a bench-scale pyrolysis setup with 2 kg per batch capacity. Polyolefin based plastics (low-density polyethylene, high-density polyethylene, and polypropylene), multilayer plastics such as biaxial oriented polypropylene (BOPP), metalized biaxial oriented polypropylene layers (MET BOPP), polyethylene terephthalate (PET), metalized polyethylene terephthalate (MET/PET), polyethylene terephthalate combined polyethylene (PET/PE), and mixed plastic waste collected from the corporation sorting center were pyrolyzed in a batch pyrolysis system with 1 kg feed to determine the oil, gas and char distributions. The performances of commercial ZSM-5 and lab synthesized ZSM-5 catalysts were compared for the pyrolysis of non-recyclable plastic wastes. Other commercial catalysts including mordenite and gamma alumina were also tested for pyrolysis experiments. The gross calorific value of oil obtained from different combinations of multilayer packaging waste varied between 10 789–7156 kcal kg⁻¹. BOPP-based plastic waste gave higher oil yield and calorific value than PET-based plastic waste. Sulfur content present in the oil from different plastic wastes was measured below the detection limit. The synthesized ZSM-5 zeolite catalyst produced a maximum oil output of 70% and corresponding gas and char of 16% and 14% for LDPE plastic. The strong acidic properties and microporous crystalline structure of the synthesized ZSM-5 catalyst enables increased cracking and isomerization, leading to an increased breakup of larger molecules to smaller molecules forming more oil yield in the pyrolysis experiments. Residual char analysis showed the maximum percentage of carbon with heavy metal concentrations (mg kg⁻¹) in the range of viz., chromium (15.36–97.48), aluminium (1.03–2.54), cobalt (1.0–5.85), copper (115.37–213.59), lead (89.12–217.3), and nickel (21.05–175.41), respectively.

Catalytic pyrolysis of mixed plastic waste to fuel oil experiment was tested with ZSM-5 zeolite (commercial and synthesized) catalysts along with other catalysts.     

Production of pyrolytic oil from ULDP plastics using silica-alumina catalyst and used as fuel for DI diesel engine

A rapid increase in the use of non-biodegradable plastics and their disposal after use has had a detrimental impact on the environment. Used plastics (used low-density polyethylene – ULDP) were selected as feedstock for the extraction of pyrolytic oil. The pyrolysis process was carried out in a semi-batch reactor with a silica alumina catalyst in the existence of fluidizing gas N₂ in a reactor at 500 °C for 60 min. The maximum liquid, gas, and char yields were 93.5 wt%, 5.4 wt%, and 1.1 wt%, respectively. Experimental analysis was carried out to obtain their functional and structural groups by FT-IR and the carbon distribution was identified by GC-MS analysis. The blends of 20%, 40%, 60%, 80%, and 100% on a volume basis were chosen for the detailed study. For the pyrolytic blends, the combustion, performance, and emission characteristics were tested at different engine loads. During combustion, the heat release rate was extremely high for neat ULDP oil because of the high energy content and a higher cetane index. The efficiency of ULDP20 was higher than in other blends, whereas NOx and smoke emissions of ULDP20 were lower among the blends but higher than diesel. ULDP20 performed similarly as diesel. Hence, ULDP20 is recommended as a fuel for the diesel engine.

Lower acidity ratio of SA catalyst influences higher yield of ULDP oil and is suggested as a novel fuel for unmodified diesel engine.     

Catalytic pyrolysis of coconut oil with Ni/SBA-15 for the production of bio jet fuel

Catalytic pyrolysis of vegetable oil is one of the potential routes to convert oil to drop-in biofuels, known as renewable hydrocarbons. In this paper, we explored catalytic pyrolysis of coconut oil using SBA-15 impregnated with Ni in proportions of 1% to 5% to produce sustainable aviation fuel. The catalysts were synthesized, calcined and then characterized by XRD, FTIR, SEM, and EDS. In order to better understand the behavior of this process, thermal and kinetic studies were carried out by thermogravimetry. The TG curves of vegetable oil with (10%) and without catalysts were obtained at heating rates of 5, 15 and 20 °C min⁻¹, in the temperature range between 30 and 600 °C. The kinetic parameters were calculated by the Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS) methods. In the kinetic study, lower heat rates promoted higher conversions and the KAS model suits the process. The results calculated for the OC sample using the two kinetic models showed an increase in the E_a energy as the conversion progressed to a certain point. Catalytic pyrolysis experiments were performed in a one-stage tubular reactor at 500 °C with a catalyst loading of 10 wt% on the basis of mass of oil. The catalyst with 5% Ni showed greater presence of hydrocarbons and greater formation of water, indicating that the deoxygenation process occurred through decarbonylation. With this, the present study was successful in the development of methodologies for obtaining hydrocarbons with a composition close to that of drop-in fuels, compared to the process carried out with vegetable oil in the absence of catalysts.

Catalytic pyrolysis of vegetable oil is one of the potential routes to convert oil to drop-in biofuels, known as renewable hydrocarbons.     

Liquid fuel from waste tires: novel refining,advanced characterization and utilization in engines with ethyl levulinate as an additive

Pyrolysis is a promising thermochemical strategy to convert scrap tires into diesel-like fuels. Crude tire pyrolysis oil (CTPO) was produced in a 10 ton rotating autoclave reactor by thermal depolymerization of the tire polymers. In this work, the prior-reported straightforward and inexpensive strategy of upgrading CTPO using a combination of silica gel (as adsorbent) and petroleum ether (as the solvent) has been scaled up with minimal loss in mass of oil and improved physicochemical characteristics (e.g., lowered acid value, low sulfur content). The upgraded TPO (StTPO) was characterized extensively to better understand their chemical compositions, physicochemical properties, and combustion characteristics. StTPO was mixed with diesel in different volumetric proportions and the blends were studied for performance and emission characteristics in a single-cylinder engine. The use of biomass-derived ethyl levulinate (EL) as a fuel oxygenate improved the cold-flow properties of StTPO–diesel blends as well as lowered the exhaust emissions (e.g., lower NO_x). A fuel blend consisting of 50% diesel, 40% StTPO, and 10% EL demonstrated the best fuel properties in the single-cylinder diesel engine.

Proposed novel upgrading method for crude tire pyrolysis oil for utilization in diesel engines.     

Effects of the NiFe2O4 nanoadditive on the performance and emission characteristics of diesel engines: ultrasonic green synthesis by T3 hormone

NiFe₂O₄ nanosheets were successfully synthesized via combined ultrasonic and combustion methods using triiodothyronine (T3) hormone as a biotemplate. Isodiesel and heavy diesel were selected as feedstocks to evaluate the ultrasound-assisted catalytic oxidation process. In this study, we focused on high performance of diesel engine with NiFe₂O₄ nanosheets. Various conditions such as catalyst dosage, hydrogen peroxide dosage, frequency range and catalyst morphologies of NiFe₂O₄ were investigated to achieve optimized conditions. High levels of sulfur compounds (98%) were removed using NiFe₂O₄ catalysts under determined conditions (1.0 g L⁻¹ catalyst, O/S mole ratio = 2, frequency = 40 kHz and morphology of the nanocatalyst = nanosheets). The nickel ferrite nano additive was mixed with isodiesel and heavy diesel using an ultrasonicator device to achieve better stability. The results indicated that under the optimum amount (1% w/v), the NiFe₂O₄ nanostructure is the best additive to reduce NO_x, CO, HC and smoke emission in diesel engines. Moreover, a change in the flash point and viscosity of diesel fuels was observed with the addition of nanosheets. NiFe₂O₄ could be recycled 3 times without a significant decrease in catalyst activity.

In the present study, nanocrystals are synthesized by the ultrasonic method in different morphologies with T3 hormone as a template. Different parameters are investigated for the synthesis of nanostructures.     

A novel and fast method to prepare a Cu-supported α-Sb2S3@CuSbS2 binder-free electrode for sodium-ion batteries

Antimony sulfide (Sb₂S₃) is a promising anode material for sodium-ion batteries due to its low cost and high theoretical specific capacity. However, poor stability and a complex preparation process limit its large-scale application. Herein, we prepare a binder-free composite electrode composed of amorphous (α-) Sb₂S₃ and copper antimony sulfide (CuSbS₂) through a simple closed-space sublimation (CSS) method. When applied as the anode in sodium-ion batteries, the α-Sb₂S₃@CuSbS₂ electrode exhibits excellent performance with a high discharge capacity of 506.7 mA h g⁻¹ at a current density of 50 mA g⁻¹ after 50 cycles. The satisfactory electrochemical performance could be ascribed to the α-Sb₂S₃–CuSbS₂ composite structure and binder-free electrode architecture, which not only retain the structural stability of the electrode but also improve the electrical conductivity. Consequently, CSS, as a scalable and environmentally friendly method, can produce a binder-free electrode in just a few minutes, demonstrating its great potential in the industrial production of sodium-ion batteries. This study may open an avenue to preparing binder-free commercial electrodes.

Antimony sulfide (Sb₂S₃) is a promising anode material for sodium-ion batteries due to its low cost and high theoretical specific capacity.     

Diatomite/Cu/Al layered double hydroxide hybrid composites for polyethylene degradation

A diatomite/Cu/Al layered double hydroxide hybrid composite (DI-LDH) was synthesized using the hydrothermal method. The synthesized DI-LDH composites were characterized via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and the Brunauer–Emmett–Teller (BET) method. Polyethylene degradation over DI-LDH was studied in a batch reactor. DI-LDH showed layered structures, indicating that the diatomite/Cu/Al double hydroxide hybrid was successfully synthesized. A significant decrease in the degradation temperature and the released amounts of CO and CO₂ was observed in the DI-LDH catalytic degradation reaction, which indicated that DI-LDH was helpful for the polyethylene degradation reaction. The X-ray photoelectron spectroscopy (XPS) results suggested that the reaction of Cu²⁺ → Cu⁺ occurred in polyethylene catalytic pyrolysis, which resulted in the decrease in the released CO amount. DI-LDH may be a potential environmental catalyst that can be applied to treat LDPE waste.

DI-LDH that can reduce the pyrolysis temperature of LDPE and the release of carbon monoxide (CO) and carbon dioxide (CO₂).     

Incorporation of Keggin-based H3PW7Mo5O40 into bentonite: synthesis,characterization and catalytic applications

The Keggin-based molybdo-substituted tungstophosphoric acid, H₃[PW₇Mo₅O₄₀]·12H₂O, were synthesized and incorporated with a bentonite clay by using a wetness impregnation method. The catalysts were characterized using several methods, such as inductively coupled plasma-atomic emission spectroscopy (ICP-AES), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), and thermogravimetric and differential thermal analysis (TG-DTA). This extremely active catalytic system provides a green strategy for the synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives under solvent free conditions at 80 °C with a good reaction mass efficiency, effective mass yield, and excellent atom economy. Both the surface acidity and catalytic activity sharply increased after H₃[PW₇Mo₅O₄₀]·12H₂O was impregnated with bentonite clay. In addition, the PW₇Mo₅/bentonite catalyst can be conveniently recovered and reused numerous times without demonstrating a significant loss in activity.

A green and efficient protocol of PW₇Mo₅/bentonite is use as an efficient and recyclable catalyst for different heterocyclic multicomponent reactions.     

Preparation of sodium silicate/red mud-based ZSM-5 with glucose as a second template for catalytic cracking of waste plastics into useful chemicals

ZSM-5 was economically synthesized with red mud (RM) and industrial sodium silicate (ISS) in a tetrapropylammonium bromide (TPABr)–glucose dual-template system. The roles of glucose, Fe and Ca in RM on the formation of ZSM-5 were investigated. The catalytic performances of the resultant ZSM-5 were tested by cracking waste plastics. It was found that the formation of ZSM-5 was attributed to a synergistic effect between TPABr and glucose. The addition of glucose decreased the pH value in the crystallization solution and thus promoted the crystallization effect. Glucose acted as a hard template to generate mesopores. Fe atoms were partly distributed in the framework and partly adsorbed in the pores of ZSM-5, and helped to generate more Lewis acid sites. Ca atoms were mainly adsorbed in the pores of ZSM-5, and showed an inhibitory effect on the formation of zeolites. The synthesized ZSM-5 showed a weakly acidic and mesoporous structure and achieved an enhanced effect on producing gaseous products (gas yield: 85.3%), especially light olefins (C _2–4) (selectivity: 77.1%) from cracking of low density polyethylene at 500 °C. The long-term cracking experiment showed that the synthesized ZSM-5 is superior in converting waste plastics to light olefins (ethylene and propene) than the commercial ZSM-5.

ZSM-5 was hydrothermally synthesized in a TPABr–glucose dual-template system with low-cost red mud and industrial sodium silicate. The resultant ZSM-5 showed superior performance in converting plastics to light olefins.     

A miniaturized electronic sensor for instant monitoring of ethanol in gasohol fuel blends

Gasoline–ethanol (gasohol) fuel blends have gained considerable attention in the petroleum and energy sectors as relatively cheaper and greener high-octane alternative fuels with gasoline-comparable efficiency in modern transportation vehicles. However, due to different combustion rates the relative concentration of ethanol in gasohol fuel blends may vary over time. Furthermore, there is a need to monitor ethanol concentration in fuel blends for quality control applications. This article reports a miniaturized electronic sensor based on an interdigital capacitor (IDC) as the transducer and a dual-imprinted titania–polyaniline composite film as the receptor. The device has an active surface area of 0.9 cm² and is easy to fabricate. The receptor material is synthesized by imprinting ethanol in both titania sol (EITS, the matrix) and polyaniline nanoparticles (EIPani, the filler), and subsequently mixing them to obtain a dual-imprinted EITS–EIPani composite. The structural and morphological characteristics of the receptor layers are determined with Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM), respectively. The IDC devices are fabricated with pristine EITS and dual-imprinted EITS–EIPani composite to test their metrological sensor characteristics in standard ethanol solutions and real-time gasohol fuel blends. The instant shift in capacitance is measured upon exposure to different concentrations of ethanol. These devices show excellent sensitivity and selectivity patterns and demonstrate reliable sensor response toward ethanol in different gasohol fuel blends with 1–10 vol% ethanol. The results of this study reveal that these miniaturized ethanol sensors are potentially useful for rapid analysis of ethanol in gasohol and may be optimized for onboard fuel quality control applications.

A schematic representation of the developed setup for ethanol sensing measurements in gasohol blends.     

Ni or Ru supported on MgO/γ-Al2O3 pellets for the catalytic conversion of ethanol into butanol

Ni- and Ru-based catalytic pellets supported on commercial γ-Al₂O₃ pellets modified with magnesium oxide have been prepared for application in the catalytic conversion of ethanol into butanol. MgO/γ-Al₂O₃ pellets with or without added metals have been characterized by XRD, SEM/EDX, TGA, N₂ physisorption, H₂ TPR, and CO₂ TPD in order to investigate the effect of MgO coverage and metal distribution on the surface and red-ox properties of the materials and, in turn, their effects on the catalytic performance. The conversion of ethanol into butanol has been investigated in a continuous flow reactor at 350–400 °C under diluted conditions (3% ethanol) in order to rank the different catalytic pellets and identify the best formulations and preparation procedures via a comparison with powder catalysts previously proposed in the literature with similar compositions. Results show enhanced catalytic performance for MgO-covered alumina pellets with respect to a pure MgO powder catalyst in spite of the lower MgO load. A significant further positive effect is found when Ni or Ru enters a solid solution with MgO.

Ni- and Ru-based catalytic pellets supported on commercial γ-Al₂O₃ pellets modified with magnesium oxide have been prepared for application in the catalytic conversion of ethanol into butanol.     

Conversion of woody oil into bio-oil in a downdraft reactor using a novel silicon carbide foam supported MCM41 composite catalyst

This study reports the synthesis of a SiC-MCM41 composite catalyst by a microwave-assisted hydrothermal process and the composite catalyst had the characteristics of MCM41 and SiC, and the surface of SiC grew evenly with a layer of MCM41 after characterization of the catalysts by various means (X-ray diffraction, Brunauer–Emmett–Teller, scanning electron microscopy). The catalyst was applied in the pyrolysis of waste oil to investigate how it influences the bio-oil component proportion compared with no catalyst, only SiC, only MCM41 catalysis and the catalytic effect was also investigated at different temperatures and different catalyst to feed ratios. In a downdraft system with a pyrolysis temperature of 550 °C, a catalyst to feed ratio of 1 : 2, and a catalytic temperature of 400 °C, 32.43% C₅–C₁₂ hydrocarbons and 41.10% mono-aromatics were obtained. The composite catalyst combined the catalytic effect of SiC and MCM41 because it increased the amount of C₅–C₁₂ hydrocarbons and decreased the amount of oxygen-containing compounds in bio-oil. After repeated uses, the composite catalyst still retained the catalytic properties.

Main flow chart of the pyrolysis process using SiC-MCM41 catalyst.     

Efficient reclamation of carbon fibers from epoxy composite waste through catalytic pyrolysis in molten ZnCl2

Carbon fiber-reinforced polymer composites have been widely used in various fields and have inevitably produced large amounts of composite waste. The recycling of carbon fibers with high value has become an active research topic at related institutions and production enterprises. In this paper, the catalytic pyrolysis of T700 carbon fiber/epoxy composites in molten salt was studied. Due to the efficient solubility of molten ZnCl₂ for the epoxy matrix and catalytic fracture of the C–N bonds by the action of Zn²⁺ ions, the epoxy composites can be completely degraded at 360 °C in 80 min under standard pressure, and the reclamation efficiency was significantly enhanced compared with conventional pyrolysis reclamation without a catalyst. The types and contents of the main oxygen-containing functional groups on the surfaces of the fibers reclaimed with ZnCl₂ were similar to those of the virgin fibers, and the graphitization structure of the carbon fibers was not destroyed in the pyrolysis process. The tensile strength of a monofilament of the fibers reclaimed with ZnCl₂ was obviously higher than that of fibers reclaimed in air; it reached a high retention rate that was about 95% that of the virgin fibers. The fibers reclaimed with ZnCl₂ after sizing exhibited a desirable reinforcing effect on the flexure performance and interlaminar shear strength of unidirectional carbon fiber/epoxy composites which was close to the performance levels of composite samples containing commercial T700 carbon fibers. Therefore, efficient technology to reclaim high-quality carbon fibers from epoxy matrices has been devised.

Carbon fibers were efficiently reclaimed from epoxy composite waste for remanufacturing through a catalytic pyrolysis in molten ZnCl₂.     

Chemical durability and degradation mechanisms of CsPbI3 as a potential host phase for cesium and iodine sequestration

Effective nuclear waste management of radioactive cesium and off-gas iodine from complex waste streams of used fuels is essential for the sustainable development of advanced nuclear fuel cycles. Once cesium and iodine are separated from their respective waste streams, host phases are required to immobilize them into a durable waste form matrix for long-term disposition. The inorganic metal halide perovskite, CsPbI₃, has a unique crystal structure capable of incorporating both cesium and iodine simultaneously. Exposure to groundwater in geological repositories is a long-term concern for waste forms, as this may cause corrosion and decrease the waste form''s ability to retain radionuclides. In this study, we explore the potential of CsPbI₃ perovskite as a promising host phase to incorporate Cs and I, and investigate its chemical durability and degradation mechanisms in an aqueous environment. CsPbI₃ was synthesized through a solution-based method and was consolidated into dense pellets by spark plasma sintering. The chemical durability of the CsPbI₃ pellets was evaluated by static leaching tests in deionized water at different temperatures of 25, 58, and 90 °C. The elemental release mechanisms and surface alteration of the monolithic CsPbI₃ pellets were investigated. Both I and Cs displayed a non-congruent leaching behavior and faster release rates as compared to Pb, particularly at longer leaching durations and higher temperatures. At the initial leaching stage, a PbI₂ alteration layer formed on the surface of the pellet due to the rapid release of Cs and I, followed by the formation of a PbI(OH) alteration layer. The activation energies for both dissolution and diffusion controlled mechanisms were determined to be 44.90 kJ mol⁻¹ and 45.40 kJ mol⁻¹ for Pb, 27.10 kJ mol⁻¹ and 40.82 kJ mol⁻¹ for I and 24.27 kJ mol⁻¹ and 23.86 kJ mol⁻¹ for Cs, respectively. These results show a clear decrease in activation energies from Pb to I and Cs, suggesting a preferential release of I and Cs. The solution-based synthesis of CsPbI₃ as a host phase for Cs and I and the fundamental understanding of the chemical durability and degradation behavior will be useful for further exploring its application for immobilizing iodine and cesium into final durable waste forms for long-term geological disposition.

Elemental release: a CsPbI₃ perovskite pellet is leached in distilled water; post-leaching analysis indicates the formation of PbI₂ and PbI(OH) alteration layers on the pellet surface, and the incongruent release of elements into the leachate.     

Phosphorus speciation analysis of fatty-acid-based feedstocks and fast pyrolysis biocrudes via gel permeation chromatography inductively coupled plasma high-resolution mass spectrometry

Renewable feedstocks, such as lignocelulosic fast pyrolysis oils and both vegetable oil and animal fats, are becoming a viable alternative to petroleum for producing high-quality renewable transportation fuels. However, the presence of phosphorus-containing compounds, mainly from phospholipids, in these renewable feedstocks is known to poison and deactivate hydrotreating catalysts during fuel production. In this work, gel permeation chromatography (GPC) combined with inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) was used to analyze feedstocks including unprocessed soybean oil, animal fat, and pyrolysis oils from red oak and milorganite to identify phosphorus species. The results have shown the presence of a wide range of different phosphorous compounds among all the samples analysed in this work. The GPC-ICP-HRMS analyses of a vegetable oil and two animal fats have shown different fingerprints based on the molecular weight of each of the samples, highlighting the structural differences among their corresponding phosphorus-containing compounds. While the presence of low-molecular-weight species, such as phospholipids, was expected, several high-molecular-weight species (MW > 10 000 Da) have been found, suggesting that high-molecular-weight micelles or liposomes might have been formed due to the high concentration of phospholipids in these samples. Results obtained through the hydroxylation of a mix of phospholipids (asolectin) and its posterior GPC-ICP-HRMS agree with this hypothesis. With respect to the lignocellulosic catalytic fast pyrolysis oil samples, the GPC-ICP-HRMS results obtained suggest that either aggregation or polymerization reactions might have occurred during the pyrolysis process, yielding phosphorus-containing compounds with an approximate molecular weight above 91 000 kDa. In addition, an aggregation phenomenom has been observed for those phosphorus species present within the fast pyrolysis oils after being stored for 3 months, especially for those pyrolysis oils contaning pre-processed feedstocks, such as milorganite.

Renewable feedstocks, such as lignocelulosic fast pyrolysis oils and both vegetable oil and animal fats, are becoming a viable alternative to petroleum for producing high-quality renewable transportation fuels.     

Preparation of sulfonated ordered mesoporous carbon catalyst and its catalytic performance for esterification of free fatty acids in waste cooking oils

Sulfonated ordered mesoporous carbon (SO₃H-OMC) solid acid catalysts from sucrose were prepared using hard-template method, and their catalytic performance as well as the deactivation mechanism for esterification of free fatty acids (FFAs) in waste cooking oils (WCOs) were evaluated. Effects of sulfonation time, sulfonation temperature and hard template structure type for the textural properties and acid properties of SO₃H-OMC were systematically investigated by N₂ adsorption–desorption, FT-IR, NH₃-TPD, TEM and strong acid density analysis. The results indicated that, SO₃H-OMC(s)-6-160 catalyst, which was prepared by using SBA-15 as hard template at sulfonation time of 6 h and sulfonation temperature of 160 °C, had well-ordered mesoporous structure and high –SO₃H groups density (2.32 mmol g⁻¹). Compared with SO₃H-APC-6-160 catalyst, cation-exchange resin D072 and SO₃H-OMC(k)-6-160 catalyst, it was found that the SO₃H-OMC(s)-6-160 catalyst exhibited highest activity (FFAs conversion was 93.8%) and good stability for the FFAs esterification, attributed to its 2D-hexagonal channels and hydrophobic surface. The –SO₃H groups being leached out of SO₃H-OMC catalysts into the liquid phase (especially methanol) would be the main reason causing catalyst deactivation.

Sulfonated ordered mesoporous carbon solid acid catalysts had excellent catalytic performance for esterification of methanol with FFAs in WCOs.     

Molecular weight distribution of raw and catalytic fast pyrolysis oils: comparison of analytical methodologies

Comprehensive analysis of the molecular weight distribution of raw and catalytic fast pyrolysis oils derived from biomass remains a key technical hurdle to understanding oil quality as it relates to downstream use and multiple methods may be necessary to accurately represent all components present. Here, we report the molecular weight distribution metrics of fast pyrolysis (FP) and catalytic fast pyrolysis (CFP) oils as determined by gel permeation chromatography (GPC) combined with UV-diode array (UV), differential refractive index (RI), and multi-angle laser light scattering (MALS) detection. The measured molar mass distributions revealed that FP oil consisted of a higher proportion of larger products relative to the low molecular weight products contained in the CFP oil. GPC/RI and UV methods showed FP oil to have higher weight-average molecular weight (M_w) and number-average molecular weight (M_n) than CFP oil based on elution time. However, GPC/MALS, determined the two oils to have similar overall molecular weight distribution metrics (M_w and M_n) and yielded values significantly higher than those determined by RI and UV detectors relative to external standards. Overall, the use of a multiple detection GPC method could enable a more accurate comparison and determination of true molecular weight metrics of bio-oils.

Comprehensive analysis of the molecular weight distribution of raw and catalytic fast pyrolysis oils remains a key technical hurdle to understanding oil quality and multiple methods may be necessary to accurately represent all components present.     

A review on non-edible oil as a potential feedstock for biodiesel: physicochemical properties and production technologies

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization. Biodiesel can be utilized as an alternative fuel to petroleum-derived diesel for the combustion engine. At present, edible crops are the primary source of biodiesel production. However, the excessive utilization of these edible crops for large-scale biodiesel production might cause food supply depletion and economic imbalance. Moreover, the utilization of edible oil as a biodiesel feedstock increases biodiesel production costs due to the high price of edible oils. A possible solution to overcome the existing limitations of biodiesel production is to utilize non-edible crops oil as a feedstock. The present study was conducted to determine the possibility and challenges of utilizing non-edible oil as a potential feedstock for biodiesel production. Several aspects related to non-edible oil as a biodiesel feedstock such as overview of biodiesel feedstocks, non-edible oil resources, non-edible oil extraction technology, its physicochemical and fatty acid properties, biodiesel production technologies, advantages and limitation of using non-edible oil as a feedstock for biodiesel production have been reviewed in various recent publications. The finding of the present study reveals that there is a huge opportunity to utilize non-edible oil as a feedstock for biodiesel production.

There is increasing concern regarding alleviating world energy demand by determining an alternative to petroleum-derived fuels due to the rapid depletion of fossil fuels, rapid population growth, and urbanization.     

Efficient deoxygenation of waste cooking oil over Co3O4–La2O3-doped activated carbon for the production of diesel-like fuel

Untreated waste cooking oil (WCO) with significant levels of water and fatty acids (FFAs) was deoxygenated over Co₃O₄–La₂O₃/AC_nano catalysts under an inert flow of N₂ in a micro-batch closed system for the production of green diesel. The primary reaction mechanism was found to be the decarbonylation/decarboxylation (deCOx) pathway in the Co₃O₄–La₂O₃/AC_nano-catalyzed reaction. The effect of cobalt doping, catalyst loading, different deoxygenation (DO) systems, temperature and time were investigated. The results indicated that among the various cobalt doping levels (between 5 and 25 wt%), the maximum catalytic activity was exhibited with the Co : La ratio of 20 : 20 wt/wt% DO under N₂ flow, which yielded 58% hydrocarbons with majority diesel-range (n-(C₁₅ + C₁₇)) selectivity (∼63%), using 3 wt% catalyst loading at a temperature of 350 °C within 180 min. Interestingly, 1 wt% of catalyst in the micro-batch closed system yielded 96% hydrocarbons with 93% n-(C₁₅ + C₁₇) selectivity within 60 min at 330 °C, 38.4 wt% FFA and 5% water content. An examination of the WCO under a series of FFA (0–20%) and water contents (0.5–20 wt%) indicated an enhanced yield of green diesel, and increased involvement of the deCOx mechanism. A high water content was found to increase the decomposition of triglycerides into FFAs and promote the DO reaction. The present work demonstrates that WCO with significant levels of water and FFAs generated by the food industry can provide an economical and naturally replenished raw material for the production of diesel.

Untreated waste cooking oil (WCO) with significant levels of water and fatty acids (FFAs) was deoxygenated over Co₃O₄–La₂O₃/AC_nano catalysts under an inert flow of N₂ in a micro-batch closed system for the production of green diesel.     

Nitrogen oxide removal by non-thermal plasma for marine diesel engines

The transportation industry plays an important role in the world economy. Diesel engines are still widely used as the main power generator for trucks, heavy machinery and ships. Removal technology for nitrogen oxides in diesel exhaust are of great concern. In this paper, a gas supply system for simulating the marine diesel engine exhaust is set up. An experimental study on exhaust denitration is carried out by using a dielectric barrier discharge (DBD) reactor to generate non-thermal plasma (NTP). The power efficiency and the denitration efficiency of different gas components by NTP are discussed. The exhaust gas reaction mechanism is analyzed. The application prospects of NTP are explored in the field of diesel exhaust treatment. The experimental results show that the power efficiency and energy density (ED) increase with the input voltage for this system, and the power efficiency is above 80% when the input voltage is higher than 60 V. The removal efficiency of NO is close to 100% by NTP in the NO/N₂ system. For the NO/O₂/N₂ system, the critical oxygen concentration (COC) increases with NO concentration. The O₂ concentration plays a decisive role in the denitration performance of the NTP. H₂O contributes to the oxidative removal of NO, and NH₃ improves the removal efficiency at low ED while slightly reducing the denitration performance at high ED. CO₂ has little effect on NTP denitration performance, but as the ED increases, the generated CO gradually increases. When simulating typical diesel engine exhaust conditions, the removal efficiency increases first and then decreases with the increase of ED in the NO/O₂/CO₂/H₂O/N₂ system. After adding NH₃, the removal efficiency of NO_x reaches up to 40.6%. It is necessary to add reducing gas, or to combine the NTP technology with other post treatment technologies such as SCR catalysts or wet scrubbing, to further increase the NTP denitration efficiency.

The experimental study on exhaust denitration is carried out by using dielectric barrier discharge (DBD) reactor to generate non-thermal plasma (NTP).