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Due to the high environmental burden of plastics, this study aimed to evaluate the environmental performance of chemical recycling of plastic waste through Life Cycle Assessment (LCA), focusing on pyrolysis oil production as the primary output. A pyrolysis plant in Almería, Spain, was chosen as a case study. The results indicate that the production of 1 L of pyrolysis oil from plastic waste generates about 0.032 kg CO2 eq and a water consumption of 0.031 m3, with other impact categories registering values of less than 0.1 kg/L or 0.01 m2a crop eq/L, reducing impacts in 17 out of 18 categories compared to fossil diesel. In addition, its chemical and physical properties, close to those of fossil diesel, suggest its suitability for internal combustion engines, although as a blend rather than a complete substitute. Chemical recycling also appears to be more environmentally favorable than incineration and landfilling in all 18 impact categories, achieving significant benefits, including a reduction in global warming of −3849 kg CO2 eq/ton, ionizing radiation of −22.4 kBq Co-60 eq/ton, and fossil resource consumption of −1807.5 kg oil eq/ton. These results, thus, highlight the potential dual role of chemical recycling of plastic waste, both in mitigating environmental impacts and in supporting circular economy goals by reducing demand for virgin plastics. However, although it appears to be a promising technology, challenges associated with high energy requirements, raw material variability, and scale infrastructure still need to be addressed to ensure industrial competitiveness and significant environmental benefits. [ABSTRACT FROM AUTHOR]

Reducing maritime greenhouse gas (GHG) emissions is challenging. As efforts to address climate change are gaining momentum, reducing the environmental impact becomes crucial for maritime short-to-medium-term sustainability. The International Maritime Organisation (IMO) has adopted Life Cycle Assessment (LCA) guidelines for estimating GHG emissions associated with alternative fuels. This paper proposes an examination of the latest IMO-adopted LCA guidelines, comparing them with existing methodologies used for the transport sector. By scrutinising these guidelines, the paper aims to provide a better understanding of the evolving landscape for GHG emission estimation within the maritime sector. The paper presents a case study that applies the newly established LCA guidelines to a promising alternative fuel pathway, i.e., waste-wood-derived pyrolysis oil. Pyrolysis oil offers an attractive option, leveraging waste materials to generate a sustainable energy source. The environmental impact of pyrolysis oils is quantified according to the IMO LCA guidelines, offering insights into its viability as a cleaner alternative as marine fuel. The results show the large potential for GHG savings offered by this pathway: upgraded pyrolysis oil can deliver significant GHG savings, and this contribution is linearly dependent of its energy share when blended with standard Heavy Fuel Oil. [ABSTRACT FROM AUTHOR]

The continuous increase in solid waste materials, such as waste tires, underscores the critical importance of recycling them to mitigate environmental impact and promote sustainable resource management. This research study evaluated the effectiveness of utilizing waste tire pyrolysis oils (WTPOs) as recycling agents for asphalt materials. The chemical composition and thermal behavior of WTPO were analyzed using Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). Mechanically, the prepared WTPO binders were assessed by measuring dynamic viscosity and changes in high- and intermediate-temperature performance grades. Additionally, the cracking susceptibility of the binders was evaluated using the Glover-Rowe (G-R) parameter. The findings indicated that WTPOs might contain water and light aromatics in varying percentages, depending on the pyrolysis process. Incorporating WTPOs enhanced the workability of asphalt mixtures and ensured a high degree of blending between recycled/aged asphalt and raw binder. A 12% WTPO dosage was identified as the most effective for enhancing fatigue and low-temperature cracking resistance, facilitating improved interactions between the virgin binder and recycled asphalt materials. Finally, utilizing WTPOs as rejuvenating agents in pavement construction supports sustainable practices by recycling waste materials and significantly improving the performance and durability of asphalt mixtures. [ABSTRACT FROM AUTHOR]

Oxygenated compounds such as acids in bio-oils (BO) have been related to the corrosion of metals and their storage instability when applied as fuels. Therefore, upgrading BO by removing acids (deacidification) can be a valuable technique to reduce corrosivity using specific separation processes. Therefore, the objective of this paper was to evaluate the effect of the water content in the solvent (aqueous methanol), the carboxylic acid content in the BO and extraction temperature on the deacidification process by liquid–liquid extraction (LLE), as well as the effect of the same parameters on the quality of the deacidified BO through physical–chemical and GC-MS analyses. The results show that an increase in the water content (5 to 25%) in the solvent and an increase in the carboxylic acids content (24.38 to 51.56 mg KOH/g) in the BO reduce the solvent's capacity to extract carboxylic acids while increasing the temperature (25 to 35 °C) of the deacidification process promoted an increase in its capacity to remove them. Consequently, the highest deacidification efficiency (72.65%) is achieved with 5% water in methanol at 25 °C for BO1 (TAN = 24.38 mg KOH/g). Therefore, the deacidification process through LLE using aqueous methanol contributed significantly to BO upgrading. [ABSTRACT FROM AUTHOR]

This paper presents the results of investigations on the pyrolysis of tyre waste in a laboratory fixed-bed batch reactor. The results regarding the influence of either the reaction temperature (425, 450, 475, and 500 °C) and the flow of the inert gas (0, 100, 300, and 500 mL/min) on product yield (referred to as pyrolysis of waste tyres) are also considered and discussed. On the basis of the abovementioned findings, the most appropriate experimental conditions were selected to contribute to a higher yield of pyrolysis oil. The sample of pyrolysis oil obtained from the experiments carried out in the selected optimal conditions (reaction time 120 min, temperature 450 °C and the inert gas flow of 100 mL/min) was subjected to calorimetric and infrared spectroscopy analysis. [ABSTRACT FROM AUTHOR]

The fast depletion of fossil fuels and growing concerns about environmental sustainability have increased interest in using biomass as a renewable energy source. Fast pyrolysis, a thermochemical conversion process, has emerged as a promising technique for converting biomass into valuable biofuels and bio-based chemicals. The aim of this literature review is to comprehensively analyze recent advances in biomass fast pyrolysis, focusing on the principles, process parameters, product yields, and potential applications of biomass fast pyrolysis. This comprehensive review, based on an in-depth analysis of 61 scientific papers and 4 patents, provides an overview of various biomass technologies (combustion, gasification, pyrolysis) used for biofuel production. It focuses on the principles, benefits and applications of these technologies and serves as a valuable resource for researchers, engineers and policy makers. Based on the wealth of information from rigorously selected sources, we explore the key process parameters and reactor types associated with each technology, providing insight into its efficiency and product composition. [ABSTRACT FROM AUTHOR]

One method of managing used car tires is decomposition by thermochemical conversion methods. By conducting the process at temperatures of 450–750 °C, three fractions are obtained from tires: oil, gas, and solid. The liquid product of the pyrolysis of used car tires is pyrolysis oil, which consists of aromatic, polyaromatic, and aliphatic hydrocarbons. Unconventional building materials were obtained from tire pyrolysis oil and the environmental impact was evaluated. Blocks made from pyrolysis oil showed mechanical strength of up to about 1700 N. No heavy metals or polycyclic aromatic hydrocarbons, which were found in the crude heavy-PO fraction, were detected in the filtrates after incubation of the block obtained from the heavy-PO fraction at 240 °C. The highest inhibition of Sorghum saccharatum shoot (74.4%) and root (57.5%) growth was observed for solid materials from the medium-PO fraction obtained at 240 °C. The most favorable values of the parameters for the process of obtaining blocks based on post-PO were an annealing temperature of 180 °C, time of 20 h, and mass ratio of catalyst to catalyzed oil of 0.045. [ABSTRACT FROM AUTHOR]

Plasma gasification is considered an environmentally friendly process to convert plastic waste into fuel oil; a prototype system is described to test and validate the plasma treatment of plastic waste as a strategic vision. The proposed plasma treatment project will deal with a plasma reactor with a waste capacity of 200 t/day. The annual plastic waste production in tons in all regions of Makkah city during 27 years for all months in the years 1994 to 2022 is evaluated. A statistics survey of plastic waste displays the average rate generation ranging from 224 thousand tons in the year 1994 to 400 thousand tons in the year 2022, with an amount of recovered pyrolysis oil; 3.17 × 105 t with the equivalent energy; 12.55 × 109 MJ, and an amount of recovered diesel oil; 2.7 × 105 t with an amount of electricity for sale 2.96 × 106 MW.h. The economic vision will be estimated, using the results of energy generated from diesel oil as an industrial fuel extracted from plastic waste equivalent to 0.2 million barrels of diesel oil, with sales revenue and cash recovery of USD 5 million, considering the sale of each one barrel of diesel extracted from plastic waste in the range of USD 25. It is important to consider that the equivalent barrels of petroleum cost, according to the organization of the petroleum-exporting countries' basket prices, up to USD 20 million. The sales profit (2022) is as follows: for diesel with a sales revenue of diesel oil, USD 5 million, with a rate of return of 4.1%, and a payback period of 3.75 years. The generated electricity reached USD 32 million for households and USD 50 million for factories. [ABSTRACT FROM AUTHOR]

Hydrodeoxygenation (HDO) is one of the most promising approaches to upgrading pyrolysis oils, but this process normally operates over expensive noble metal catalysts (e.g., Ru/C, Pt/Al2O3) under high-pressure hydrogen gas, which raises processing costs and safety concerns. In this study, a wood-derived pyrolysis oil was upgraded in supercritical ethanol using formic acid as an in situ hydrogen source at 300 °C and 350 °C, over a series of nickel–molybdenum-tungsten (NiMoW) catalysts supported on different materials, including Al2O3, activated carbon, sawdust carbon, and multiwalled nanotubes (MWNTs). The upgrading was also conducted under hydrogen gas (an ex situ hydrogen source) for comparison. The upgrading process was evaluated by oil yield, degree of deoxygenation (DOD), and oil qualities. The NiMoW/MWNT catalyst showed the best HDO performance among all the catalysts tested at 350 °C, with 74.8% and 70.9% of oxygen in the raw pyrolysis oil removed under in situ and ex situ hydrogen source conditions, respectively, which is likely owing to the large pore size and volume of the MWNT support material, while the in situ hydrogen source outperformed the ex situ hydrogen source in terms of upgraded oil yields and qualities, regardless of the catalysts employed. [ABSTRACT FROM AUTHOR]

Recycling used plastic can help reduce the amount of plastic waste generated. Existing methods, namely the process of pyrolysis, are chemical heating processes that decompose plastics in the absence of oxygen. This decomposes the plastics in a controlled environment in order to produce fuel from waste. The present study consequently investigated the physical and chemical properties of pyrolysis oil derived from plastic bottle caps (WPBCO) and the effects on the engine performance and emission characteristics of a diesel engine operating on WPBCO. The experiments were conducted with a single-cylinder diesel engine operating at a constant 1500 rpm under various engine loading conditions. The experimental results of the chemical properties of test fuels indicated that WPBCO and diesel fuels have similar functional groups and chemical components. In comparison, WPBCO has a lower kinematic viscosity, density, specific gravity, flash point, fire point, cetane index, and distillation behavior than diesel fuel. However, WPBCO has a high gross calorific value, which makes it a suitable replacement for fossil fuel. In comparison to diesel fuel, the use of WPBCO in diesel engines results in increased brake-specific fuel consumption (BSFC) and brake thermal efficiency (BTE) under all load conditions. The combustion characteristics of the engine indicate that the use of WPBCO resulted in decreased in-cylinder pressure (ICP), rate of heat release (RoHR), and combustion stability compared to diesel fuel. In addition, the combustion of WPBCO advances the start of combustion more strongly than diesel fuel. The use of WPBCO increased emissions of NOX, CO, HC, and smoke. In addition, the particulate matter (PM) analysis showed that the combustion of WPBCO generated a higher PM concentration than diesel fuel. When WPBCO was combusted, the maximum rate of soot oxidation required a lower temperature, meaning that oxidizing the soot took less energy and that it was easier to break down the soot. [ABSTRACT FROM AUTHOR]

Plastics are engineering marvels that have found widespread use in all aspects of modern life. However, poor waste management practices and inefficient recycling technologies, along with their extremely high durability, have caused one of the major environmental problems facing humankind: waste plastic pollution. The upcycling of waste plastics to chemical feedstock to produce virgin plastics has emerged as a viable option to mitigate the adverse effects of plastic pollution and close the gap in the circular economy of plastics. Pyrolysis is considered a chemical recycling technology to upcycle waste plastics. Yet, whether pyrolysis as a stand-alone technology can achieve true circularity or not requires further investigation. In this study, we analyzed and critically evaluated whether oil obtained from the non-catalytic pyrolysis of virgin polypropylene (PP) can be used as a feedstock for naphtha crackers to produce olefins, and subsequently polyolefins, without undermining the circular economy and resource efficiency. Two different pyrolysis oils were obtained from a pyrolysis plant and compared with light and heavy naphtha by a combination of physical and chromatographic methods, in accordance with established standards. The results demonstrate that pyrolysis oil consists of mostly cyclic olefins with a bromine number of 85 to 304, whereas light naphtha consists of mostly paraffinic hydrocarbons with a very low olefinic content and a bromine number around 1. Owing to the compositional differences, pyrolysis oil studied herein is completely different than naphtha in terms of hydrocarbon composition and cannot be used as a feedstock for commercial naphtha crackers to produce olefins. The findings are of particular importance to evaluating different chemical recycling opportunities with respect to true circularity and may serve as a benchmark to determine whether liquids obtained from different polyolefin recycling technologies are compatible with existing industrial steam crackers' feedstock. [ABSTRACT FROM AUTHOR]

Plastic waste is the largest volume of waste and the most discarded, and it has a direct negative impact on the environment. Therefore, the pyrolysis oil process is an essential and sustainable solution to reduce plastic waste accumulation. However, the plastic pyrolysis fuel performance in diesel engines is reduced due to its lower cetane number. Diesel and pyrolysis oil were blended in ratios of 90:10 (BP10), 80:20 (BP20), 70:30 (BP30), 60:40 (BP40), and 50:50 (BP50) and applied in a single-cylinder diesel engine to investigate the engine performance and exhaust emission. The long ignition delay, thermal efficiency drops, and emission growth were found regarding the higher blended fuel ratios. BP30 was selected to evaluate the performance and combustion characteristics of blended plastic pyrolysis oil and diesel fuel blends by enhancing an unmodified engine using low hydrogen additions (1000 ppm) and advanced timing adjustment. The hydrogen injected into the intake manifold, along with the advanced fuel injection timing (−16.5 CA°BTDC), affected engine performance and emissions (CO, HC, and NO) at 1500 rpm under 25%, 50%, and 75% of the maximum load compared with diesel fuel. The results showed that the hydrogen addition was very positive for both engine performance and emission reduction, as the expanded flammability of the hydrogen promoted a wide range of combustion within the cylinder, whereas the advanced injection timing achieved improved engine performance but produced higher emissions compared to B7 at all engine loads. [ABSTRACT FROM AUTHOR]

Pyrolysis is a low-emission and sustainable thermochemical technique used in the production of biofuels, which can be used as an alternative to fossil fuels. Understanding the kinetic characterization of biomass pyrolysis is essential for process upscaling and optimization. There is no accepted model that can predict pyrolysis kinetics over a wide range of pyrolysis conditions and biomass types. This study investigates whether or not the classical lumped kinetic model with a three-competitive reaction scheme can accurately predict the walnut shell pyrolysis product yields. The experimental data were obtained from walnut shell pyrolysis experiments at different temperatures (300–600 °C) using a fixed-bed reactor. The chosen reaction scheme was in good agreement with our experimental data for low temperatures, where the primary degradation of biomass occurred (300 and 400 °C). However, at higher temperatures, there was less agreement with the model, indicating that some other reactions may occur at such temperatures. Hence, further studies are needed to investigate the use of detailed reaction schemes to accurately predict the char, tar, and gas yields for all types of biomass pyrolysis. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effect of the supplied pyrolysis oils (oils obtained from the pyrolysis of used tyres and the depolymerisation of plastics) on the activity of the hydrodesulphurisation catalyst. Each pyrolysis oil was added at 20% weight to a standard feedstock and processed on pilot plant reactors under the set conditions of a commercial unit, including an activated catalyst. Following the catalyst stabilisation, the standard material was changed to the mixture with the pyrolysis oils. The reaction conditions, particularly the reaction temperature, were controlled. The results of the product analyses were compared with the EN 590 standard for evaluating diesel fuel; the hydrogenated mixed fuel meets most requirements. Only the density, flash point, distillation curve and lubricity have minor deviations, which could be adjusted by treating the sample before or after hydrogenation. The properties of the products, in terms of the low-temperature properties, were also investigated. The tyre-derived pyrolysis oils showed improved low-temperature properties, possibly due to the higher levels of the aromatic hydrocarbons. The pyrolysis oil obtained from the depolymerisation of the plastics was found to be more suitable for use in refineries without substantially impacting the existing technologies. For the tyre-derived pyrolysis oils, higher reaction temperatures were required for processing, which could affect the catalyst operation. [ABSTRACT FROM AUTHOR]

Alternative chemical and fuel oil produced from plastic waste may play a key role in national sustainable development. The Korean government has promoted several waste recycling policies including waste to energy. Here, we focus on the investigation of the oil and facility characteristics of plastic waste pyrolysis. Four pyrolysis facilities, which had different pyrolysis processes and produced various oil properties, were chosen in order to develop an advanced waste recycling policy. Pyrolysis oil recovery efficiency and chemical characteristics were influenced by feedstock and pyrolysis conditions. In terms of pyrolysis gases, the gas quantity was different due to the pyrolyzer operation conditions, but the characteristics of gas composition were not especially distinguished. In addition, air pollutants, such as carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), and hydrogen sulfide (H2S) from the pyrolysis process were analyzed to evaluate the environmental effects on the surrounding area. The air pollutant concentration varied, but those from the process were adequately controlled. From the aforementioned results, several improvements have been deduced to manage the pyrolysis oil facility and product in advanced policy decisions. [ABSTRACT FROM AUTHOR]

Equations of state are powerful tools for modeling thermophysical properties; however, so far, these have not been developed for shale oil due to a lack of experimental data. Recently, new experimental data were published on the properties of Kukersite shale oil, and here we present a method for modeling the properties of the gasoline fraction of shale oil using the PC-SAFT equation of state. First, using measured property data, correlations were developed to estimate the composition of narrow-boiling-range Kukersite shale gasoline samples based on the boiling point and density. These correlations, along with several PC-SAFT equations of the states of various classes of compounds, were used to predict the PC-SAFT parameters of aromatic compounds present in unconventional oil-containing oxygen compounds with average boiling points up to 180 °C. Developed PC-SAFT equations of state were applied to calculate the temperature-dependent properties (vapor pressure and density) of shale gasoline. The root mean square percentage error of the residuals was 13.2%. The average absolute relative deviation percentages for all vapor pressure and density data were 16.9 and 1.6%, respectively. The utility of this model was shown by predicting the vapor pressure of various portions of the shale gasoline. The validity of this model could be assessed for oil fractions from different deposits. However, the procedure used here to model shale oil gasoline could also be used as an example to derive and develop similar models for oil samples with different origins. [ABSTRACT FROM AUTHOR]

Pyrolysis is considered the most promising way to convert biomass to fuels. Upgrading biomass pyrolysis oil is essential to produce high quality hydrocarbon fuels. Upgrading technologies have been developed for decades, and this review focuses on the hydrodeoxygenation (HDO). In order to declare the need for upgrading, properties of pyrolysis oil are firstly analyzed, and potential analysis methods including some novel methods are proposed. The high oxygen content of bio-oil leads to its undesirable properties, such as chemical instability and a strong tendency to re-polymerize. Acidity, low heating value, high viscosity and water content are not conductive to making bio-oils useful as fuels. Therefore, fast pyrolysis oils should be refined before producing deoxygenated products. After the analysis of pyrolysis oil, the HDO process is reviewed in detail. The HDO of model compounds including phenolics monomers, dimers, furans, carboxylic acids and carbohydrates is summarized to obtain sufficient information in understanding HDO reaction networks and mechanisms. Meanwhile, investigations of model compounds also make sense for screening and designing HDO catalysts. Then, we review the HDO of actual pyrolysis oil with different methods including two-stage treatment, co-feeding solvents and in-situ hydrogenation. The relative merits of each method are also expounded. Finally, HDO catalysts are reviewed in order of time. After the summarization of petroleum derived sulfured catalysts and noble metal catalysts, transitional metal carbide, nitride and phosphide materials are summarized as the new trend for their low cost and high stability. After major progress is reviewed, main problems are summarized and possible solutions are raised. [ABSTRACT FROM AUTHOR]

The exponential increase of plastic production produces 100 million tonnes of waste plastics annually which could be converted into hydrocarbon fuels in a thermal cracking process called pyrolysis. In this research work, a direct current (DC) thermal plasma circuit is designed and used for conversion of low density polyethylene (LDPE) into diesel oil in a laboratory scale pyrolysis reactor. The experimental setup uses a 270 W DC thermal plasma at operating temperatures in the range of 625 °C to 860 °C for a low density polyethylene (LDPE) pyrolysis reaction at pressure = 􀀀0.95, temperature = 550 °C with τ = 30 min at a constant heating rate of 7.8 °C/min. The experimental setup consists of a vacuum pump, closed system vessel, direct current (DC) plasma circuit, and a k-type thermocouple placed a few millimeters from the reactant sample. The hydrocarbon products are condensed to diesel oil and analyzed using flame ionization detector (FID) gas chromatography. The analysis shows 87.5% diesel oil, 1,4-dichlorobenzene (Surr), benzene, ethylbenzene and traces of toluene and xylene. The direct current (DC) thermal plasma achieves 56.9 wt. % of diesel range oil (DRO), 37.8 wt. % gaseous products and minimal tar production. The direct current (DC) thermal plasma shows reliability, better temperature control, and high thermal performance as well as the ability to work for long operation periods. [ABSTRACT FROM AUTHOR]

We investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore volume and surface area. The extent of these structural changes was sensitive to the initial carbide structure and was lower under actual hydroprocessing conditions indicating the possibility of further improving the hydrothermal stability of Mo carbides by optimizing catalyst structure and operating conditions. Mo carbides were active in acetic acid conversion in the presence of liquid water, their activity being comparable to that of Ru/C. The results suggest that effective and inexpensive bio-oil hydroprocessing catalysts could be designed based on Mo carbides, although a more detailed understanding of the structure-performance relationships is needed, especially in upgrading of more complex reaction mixtures or real bio-oils. [ABSTRACT FROM AUTHOR]

The aim of this paper is for the production of oils processed in refineries to come from the pyrolysis of real waste from the high plastic content rejected by the recycling industry of the Basque Country (Spain). Concretely, the rejected waste streams were collected from (1) a light packaging waste sorting plant, (2) the paper recycling industry, and (3) a waste treatment plant of electrical and electronic equipment (WEEE). The influence of pre-treatments (mechanical separation operations) and temperature on the yield and quality of the liquid fraction were evaluated. In order to study the pre-treatment effect, the samples were pyrolyzed at 460 °C for 1 h. As pre-treatments concentrate on the suitable fraction for pyrolysis and reduce the undesirable materials (metals, PVC, PET, inorganics, cellulosic materials), they improve the yield to liquid products and considerably reduce the halogen content. The sample with the highest polyolefin content achieved the highest liquid yield (70.6 wt.% at 460 °C) and the lowest chlorine content (160 ppm) among the investigated samples and, therefore, was the most suitable liquid to use as refinery feedstock. The effect of temperature on the pyrolysis of this sample was studied in the range of 430–490 °C. As the temperature increased the liquid yield increased and solid yield decreased, indicating that the conversion was maximized. At 490 °C, the pyrolysis oil with the highest calorific value (44.3 MJ kg−1) and paraffinic content (65% area), the lowest chlorine content (128 ppm) and more than 50 wt.% of diesel was obtained. [ABSTRACT FROM AUTHOR]

The calorific value of household refuse (HR) is greatly improved after classification, which includes the implementation of sufficient pyrolysis conditions. Therefore, a better pyrolysis effect can be achieved by co-pyrolysis with industrial solid waste (ISW) with high calorific value. In this work, HR and ISW were used as raw materials for co-pyrolysis experiments. The influence on the distribution of three-phase products after co-pyrolysis, the concentration of heavy metals and dioxins in the flue gas, and the distribution of PCDD/Fs isomers were studied. The results showed that, at a temperature of 600 °C and H/C = 1.3, of the formed material, the quantity of pyrolysis gas was approximately 27 wt.%, and the quantity of pyrolysis oil was approximately 40.75 wt.%, which mainly contained alkanes, olefins, and aromatic hydrocarbons. When S/C = 0.008, pyrolysis gas accounted for 25.95 wt.% of the formed material, and pyrolysis oil for 41.95 wt.% of the formed material. The ignition loss rate of pyrolysis coke was approximately 20%, and the maximal calorific value was 14,217 KJ/kg. According to the thermogravimetric experiment, the co-pyrolysis of HR and ISW can promote the positive reaction of pyrolysis, and the weight loss reached 62% at 550 °C. The emission of gaseous heavy metals was relatively stable, and the concentration of heavy metals slightly decreased. The main heavy metals in the ash were Cu, Fe, and Zn. The emission of dioxins could be effectively reduced by the pyrolysis of HR with ISW, and the produced dioxins were mainly synthesized from de novo synthesis. After pyrolysis, the toxic equivalent of dioxins in the flue gas was reduced from 0.69 to 0.29 ng I-TEQ/Nm3, and the distribution of dioxin isomers in the flue gas had little influence. The experimental results provide a theoretical basis for the application of co-pyrolysis technology with HR and ISW. [ABSTRACT FROM AUTHOR]

The use of pyrolysis oil can be seen as an alternative fuel for maritime transport. However, pyrolysis oil from tires must be desulfurized for this. Recently, this can be done by hydrodynamic cavitation. This process does not require oxidation chemicals but only water, a cavitation generator, and a pump to drive it. In the literature, this concept has been successfully tested on model fuels. In this study, the cavitation generator for the desulfurization of waste tire pyrolysis oil was printed from polylactic acid-based on simulations of the optimal design, which allows for much cheaper production and easy replacement in case of wear or testing of alternative designs. After 60 min of treatment at 5 bar inlet pressure, a desulfurization of almost 33% was achieved. Furthermore, an interaction analysis showed that only from a pyrolysis oil content of 5.5 to 6% does hydrodynamic cavitation have an effective effect on desulfurization. [ABSTRACT FROM AUTHOR]

Spent coffee grounds contain lipids (fatty acids) in addition to cellulose, hemicellulose, and lignin. The reaction process for upgrading biocrude oil produced from spent coffee grounds is different from that followed for upgrading biomass pyrolysis oil, such as processes that utilize sawdust. The feasibility of upgrading coffee biocrude oil through a supercritical ethanol reaction with plastic pyrolysis oil and through catalytic cracking for the improvement of the undesirable properties of biocrude oil, caused by the presence of oxygenated compounds, was evaluated. The initial oxygen content of the coffee biocrude oil was 16.9 wt%. The oil comprised a total content of 40.9% fatty acids, as found by analyzing the GC-MS peak area. After the supercritical ethanol reaction at 340 ∘ C, the oxygen content was decreased to 9.9 wt%. When the MgNiMo/AC catalyst was applied to the supercritical reaction, the oxygen content was further decreased to 8.5 wt%. The esterification of the fatty acids in the biocrude oil with ethanol converted them to esters. After the supercritical reaction of coffee biocrude oil with plastic pyrolysis oil (1:2 (w/w)), the oxygen content was 6.4 wt%. After the catalytic cracking of the biocrude oil by Ni/MCM-41 at 400 ∘ C, the fatty acids were converted to hydrocarbons, C9 to C21, and the oxygen content decreased to a final value of 2.8 wt%. [ABSTRACT FROM AUTHOR]

The high-energy potential of wastewater sewage sludge (SS) produced in large amounts around the world makes it an attractive feedstock for fuels and energy sectors. Thermochemical valorization relying on pyrolysis of SS followed by hydrotreatment of pyrolysis oil (Py-SS) might even allow the integration of SS into existing oil refineries. In the present study, catalytic hydrotreatment of Py-SS was performed over a NiCuMo-P-SiO2 catalyst in a batch reactor at temperatures in the range of 200–390 °C. Due to sulfur presence in the feed, the increasing reaction temperature induced in situ transformation of metallic Ni into Ni3S2 in the catalyst. In contrast, the Ni3P active phase possessed remarkable stability even at the harshest reaction conditions. The oxygen content in the reaction products was decreased by 59%, while up to 52% of N and 89% of S were removed at 390 °C. The content of free fatty acids was greatly reduced by their conversion to n-alkanes, while the larger amount of volatile aromatics was generated from high molecular mass compounds. The quality of oil-derived products greatly changed at elevated temperatures, providing strong evidence of effective upgrading via decarboxy(ny)lation, hydrogenation, and hydrocracking transformations. [ABSTRACT FROM AUTHOR]