Search Results (199)

This study systematically investigates the catalytic degradation performance and reaction mechanism of Fe₈₀P₁₃C₇ Metal Glass (MG) in a Fenton-like system for the removal of Methylene Blue (MB). Kinetic experiments on degradation reveal that under acidic conditions (pH = 3), Fe₈₀P₁₃C₇ MG exhibits exceptional catalytic activity, achieving complete degradation of a 50 mg/L MB solution within 12 min. Its degradation rate significantly surpasses that of Fe₇₈Si₉B₁₃ MG and commercially available ZVI powder. Key parameters such as catalyst dosage, H₂O₂ concentration, solution pH, and initial dye concentration were systematically examined to determine the optimal reaction conditions. The characterization results indicate that Fe₈₀P₁₃C₇ MG maintains high activity even after multiple cycles of use, attributed to surface selective corrosion and crack formation during the reaction process. This “self-renewal” mechanism continuously exposes fresh active sites. Mechanistic studies confirm that the degradation process is driven by an efficient redox cycle between Fe²⁺/Fe³⁺ within the material, ensuring sustained and stable generation of •OH, which ultimately leads to the complete mineralization of MB molecules. This research provides solid experimental and theoretical foundations for the application of Fe₈₀P₁₃C₇ MG in dye wastewater treatment. Full article

ZSM-5 zeolites with varying aluminum content were subjected to steam treatments of different severities by adjusting the temperature, duration, and water vapor pressure. The steamed samples were characterized using a range of analytical techniques. A quantitative assessment of the aluminum species—namely, tetrahedrally coordinated framework Al, dislodged framework Al, non-framework pentacoordinated Al, and non-framework hexacoordinated Al—was achieved through a combination of EDX analysis on Cs-exchanged materials and quantitative ²⁷Al MAS NMR spectroscopy, including spectral simulation. Contrary to previous reports, the catalytic activity per framework Al site in unsteamed ZSM-5 increases with aluminum content at low Si/Al ratios, aligning with recently proposed medium effects. Notably, at the point of maximum activity enhancement due to steaming, equivalent amounts (1:1) of framework and dislodged framework Al—both in tetrahedral coordination—are observed. The maximum enhancement factor per framework Al site, for a given material and reaction, remains independent of the specific steaming conditions (temperature, time, and pressure). However, the degree of activity enhancement varies with the type of reaction: it is more pronounced for n-hexane cracking (α-test) than for m-xylene isomerization. This suggests that both catalyst modification and reaction characteristics contribute to the observed steam-induced activity enhancement. A synergistic interaction between Brønsted and Lewis acid sites appears to underpin these effects. One plausible mechanism involves the strengthening of Brønsted acidity in the presence of adjacent Lewis acid sites. This enhancement is expected to be more significant for n-hexane cracking, which demands higher acid strength compared to m-xylene isomerization. In cases of n-hexane cracking, the increased acid strength and the formation of olefins via reactions on Lewis acid sites may act cooperatively. Importantly, the dislodged framework Al species—tetrahedrally coordinated in the hydrated catalyst at ambient temperature and functioning as Lewis acid sites in the dehydrated zeolite under reaction conditions—are directly responsible for the observed enhancement in acid activity. The transformation of framework Al into dislodged framework Al species is reversible, as demonstrated by hydrothermal treatment of the steamed samples at 150–200 °C. Nonetheless, reinsertion of Al into the framework is not fully quantitative: a portion of the dislodged framework Al is irreversibly converted into non-framework penta- and hexacoordinated species during the hydrothermal process. Among these, non-framework pentacoordinate Al species may serve as counterions to balance the lattice charges associated with framework Al. Full article

This article presents the programme for the characterisation of earth mortars stabilised with experimental pozzolanic material from fluid catalytic cracking (FCC). This study aims to establish the optimal ratio for adding pozzolan to stabilise earth mortars. Ash may be used in conservation processes, as it presents suitable pozzolanic properties. Based on the starting premise that its application does not cause chromatic variations in the final mortar and displays resistance to damage from chlorides and extreme temperatures, it can be considered ideal for this purpose. The process of transformation into ash is linked to the production of naphthas and refined petroleum products, where the mineral is a catalyst for the reaction. With use, the mineral tends to shrink, losing the necessary properties for this process. Over the last decade, this process, which is widely used in the petrochemical industry, has generated a volume of waste of up to 3000 tons per day. The amount of waste generated is of interest for its reuse, and a rise is observed in preliminary studies, which confirm that this material is pozzolanic and non-toxic. This offers the possibility of studying this addition to stabilise materials and constructions manufactured with earth. Full article

Studies were conducted on the hydrogen-free processing of model alkanes, straight-run gasoline, and catalytic cracking gasoline using a new synthesized Co-Mo-Ce/ZSM + Al₂O₃ nanocatalyst, which demonstrated high activity in desulfurization. Thus, the mass fraction of sulfur in the resulting gasoline was reduced by almost three times compared to the initial value of 0.0776% to 0.0354% as a result of hydrogen-free processing of straight-run gasoline. The amount of sulfur in the resulting product was reduced by almost an order of magnitude with hydrogen-free processing of catalytic cracked gasoline: from 0.1650 in the original gasoline to 0.0123%. The octane number of the refined straight-run gasoline was 77.9–80.9 according to the research method (RM) and 61.13–65.8 with the motor method (MM). Physical and chemical methods of analysis (BET, TPD-NH₃, TEM, SEM, and XRD) revealed that nano-structured acid sites coexist with nano-dispersed metallic sites on the surface of the Co-Mo-Ce/ZSM + Al₂O₃ catalyst. The functioning of these two types of nano-active sites (metallic and acidic) ensures the polyfunctionality of the catalytic action of the nanoparticles. The following reactions occur simultaneously in the hydrogen-free processing: isomerization, dehydrogenation, dehydrocyclization. Hydrogen-free processing of low-octane gasoline fractions on nanosized zeolite-containing catalysts is one of the most promising methods to obtain high-octane motor gasoline. Full article

This study addresses the critical issue of environmental pollution from plastic waste by investigating an effective chemical recycling method for polyethylene terephthalate (PET) via neutral catalytic hydrolysis. We utilized a recoverable and regenerable composite catalyst based on cracking zeolite and γ-Al₂O₃, which possesses both Brønsted and Lewis acidic sites that facilitate the depolymerization of PET into its constituent monomers, terephthalic acid (TPA) and ethylene glycol (EG). This investigation reveals that the catalytic performance is strongly dependent on the total acid site concentration and the specific nature of these sites. A key finding is that a balanced acidic profile with a high proportion of Brønsted acid sites is crucial for enhancing PET hydrolysis attributed to a significant decrease in the activation energy of the reaction. The experiments were conducted in a stirred stainless-steel autoclave reactor, where key parameters such as temperature (210–230 °C), the PET-to-water ratio (1:2 to 1:5), and reaction time were systematically varied. Under optimal conditions of 210 °C and a 6 h reaction time, the process achieved near-complete PET depolymerization (99.5%) and a high TPA yield (90.24%). The catalyst demonstrated remarkable recyclability, maintained its activity over multiple cycles and was easily regenerated. Furthermore, the recovered TPA was of high quality, with a purity of 98.74% as confirmed by HPLC, and exhibited a melt crystallization temperature 14 °C lower than that of the commercial standard. These results not only demonstrate the efficiency and sustainability of neutral catalytic hydrolysis using zeolite/alumina composites but also provide valuable insights for designing advanced catalysts with tunable acidic properties. By demonstrating the importance of tuning acidic properties, specifically the balance between Brønsted and Lewis sites, this work lays a foundation for developing more effective catalysts that can advance circular economy goals for PET recycling. Full article

Fluid Catalytic Cracking (FCC) constitutes a critical process in petroleum refining, facing increasing pressure to align with sustainable development goals by improving energy efficiency and reducing environmental impact. This study tackles a multi-objective optimization challenge in FCC operations, seeking to simultaneously maximize the gasoline production and minimize the coke yield—the latter being directly linked to $\mathrm{C}{\mathrm{O}}_2$ emissions in FCC. A data-driven optimization model leveraging a dual Long Short-Term Memory architecture is developed to capture complex relationships between operating variables and product yields. To efficiently solve the model, an Improved Multi-Objective Whale Optimization Algorithm (IMOWOA) is proposed, integrating problem-specific adaptive multi-neighborhood search and dynamic restart mechanisms. Extensive experimental evaluations demonstrate that IMOWOA achieves superior convergence characteristics and comprehensive performance compared to established multi-objective algorithms. Relative to the yields before optimization, the proposed methodology increases the gasoline yield by 0.32% on average, coupled with an average reduction of 0.11% in the coke yield. For the studied FCC unit with an annual processing capacity of 2.6 million tons, the coke reduction corresponds to an annual $\mathrm{C}{\mathrm{O}}_2$ emission reduction of approximately 10,277 tons, delivering benefits to sustainable FCC operations. Full article

Cashew nut shell liquid (CNSL) is a byproduct of cashew processing that has largely been overlooked as a biomass resource for biodiesel production. While some research has been conducted on CNSL in diesel engines, there remains a lack of studies on using processed CNSL with industrial waste catalysts for diesel engines. This study focuses on the performance and emissions of catalytically cracked CNSL (CC-CNSL) created with fly ash as a catalyst. Blends of 25%, 50%, 75%, and 100% CC-CNSL-diesel were used as a fuel in a single-cylinder diesel engine under different load conditions. The CC-CNSL25 blend, which contains 25% CC-CNSL, outperformed the others with a 2% increase in brake thermal efficiency. Additionally, it showed substantial reductions in emissions, i.e., 11.76% less carbon monoxide, 9.09% reduced smoke density, 8.57% lower hydrocarbon emissions, and 5.27% decreased specific fuel consumption compared to conventional diesel at full load. This research highlights fly ash-catalyzed CNSL processing as an effective method for converting agricultural waste into high-quality biodiesel. It offers a dual advantage as a sustainable fuel source while addressing waste management challenges. Full article

Seaweed holds significant promise as a renewable feedstock for bioenergy due to its rapid growth, carbon sequestration capacity, and non-competition with terrestrial agriculture. This review examines recent progress in multi-method synergies for optimized energy conversion from seaweed biomass. Physical pre-treatments (e.g., drying, milling, ultrasound, microwave) enhance substrate accessibility but face energy intensity constraints. Chemical processes (acid/alkali, solvent extraction, catalysis) improve lipid/sugar recovery and bio-oil yields, especially via hydrodeoxygenation (HDO) and catalytic cracking over tailored catalysts (e.g., ZSM-5), though cost and byproduct management remain challenges. Biological methods (enzymatic hydrolysis, fermentation) enable eco-friendly valorization but suffer from scalability and enzymatic cost limitations. Critically, integrated approaches—such as microwave-solvent systems or hybrid thermochemical-biological cascades—demonstrate superior efficiency over singular techniques. Upgrading pathways for liquid bio-oil (e.g., HDO, catalytic pyrolysis) show considerable potential for drop-in fuel production, while solid-phase biochar and biogas offer carbon sequestration and circular economy benefits. Future priorities include developing low-cost catalysts, optimizing process economics, and scaling synergies like hydrothermal liquefaction coupled with catalytic upgrading to advance sustainable seaweed biorefineries. Full article

Biofuels and value-added chemicals can be produced using biomass. These products can substitute the corresponding petroleum-based ones, reducing the carbon footprint, ensuring domestic production, and minimizing/exploiting organic wastes in a circular economy philosophy. Natural mineral-based catalysts seem to be a promising, eco-friendly, and low-cost approach for biomass valorization. This article attempts to highlight the potential of natural mineral-based catalysts for various processes targeting the above valorization. Natural zeolites and clays can be used as catalysts/CO₂ adsorbents and catalytic supports in various biorefinery processes (pyrolysis, gasification, hydrothermal liquefaction, esterification/transesterification, hydrotreatment, cracking, isomerization, oxidation, condensation, etc.). Acid/base, redox, and textural properties of these materials are key factors for their catalytic performance and can be easily regulated by suitable treatments, like calcination, acid/base-washing, metal impregnation, doping, etc., which are discussed in this article. The application of natural minerals in biorefinery processes makes them greener, cost-effective, and easily scalable. Full article

To address the greenhouse effect and environmental pollution stemming from fossil fuels, the development of new energy sources is widely regarded as a critical pathway toward achieving carbon neutrality. Microalgae, as a feedstock for third-generation biofuels, have emerged as a research hotspot for producing biojet fuel due to their high photosynthetic efficiency, non-competition with food crops, and potential for carbon reduction. This paper provides a systematic review of technological advancements in the catalytic hydrogenation of microalgal oil for biojet fuel production. It specifically focuses on the reaction mechanisms and catalyst design involved in the hydrogenation–deoxygenation and cracking/isomerization processes within the Oil-to-Jet (OTJ) pathway. Furthermore, the paper compares the performance differences among various catalyst support materials and between precious and non-precious metal catalysts. Finally, it outlines the current landscape of policy support and progress in industrialization projects globally. Full article

Aluminum polyoxocations were introduced into a lamellar zirconium phosphate (α-ZrP) via ion exchange. The Al polyoxocation pillars transformed into Al₂O₃ particles within the interlayer zone after calcination at 673 K. The resulting Al₂O₃-α-ZrP exhibited a large BET surface area and medium-strength acidity. Pt-supported Al₂O₃-α-ZrP was used as a catalyst for hydrocracking squalene and Botryococcus braunii oil in an autoclave batch system. In a one-step squalene hydrocracking process, the yield of jet-fuel-range hydrocarbons was 52.8% on 1 wt.% Pt/Al₂O₃-α-ZrP under 2 MPa H₂ at 623 K for 3 h. A two-step process was designed with the first step at 523 K for 1 h and the second at 623 K for 3 h. During the first step, the squalene was hydrogenated to squalane without cracking, and in the second step, the squalane was hydrocracked. This two-step catalytic process increased the yield of jet-fuel-range hydrocarbons to 65% in squalene hydrocracking. For algae oil hydrocracking, the jet-fuel-range hydrocarbons occupied 66% of the total products in the two-step reaction. Impurities in algae oil, mainly fatty acids, did not affect the yield of jet-fuel-range hydrocarbons because they were deoxygenated into hydrocarbons during the reaction. The activity of Pt/Al₂O₃-α-ZrP remained unchanged after four reuses through simple filtration. Full article

Catalytic upgrading of vacuum residue (VR) is critical for enhancing fuel yield and reducing waste in petroleum refining. This study explores VR cracking over a novel cerium-loaded acidified metakaolinite catalyst (MKA800–20%Ce) prepared via calcination at 800 °C, acid leaching, and wet impregnation with 20 wt.% Ce. The catalyst was characterized using FTIR, BET, XRD, TGA, and GC–MS to assess structural, textural, and thermal properties. Catalytic cracking was carried out in a fixed-bed batch reactor at 350 °C, 400 °C, and 450 °C. The MKA800@Ce20% catalyst showed excellent thermal stability and surface activity, especially at higher temperatures. At 450 °C, the catalyst yielded approximately 11.72 g of total liquid product per 20 g of VR (representing a ~61% yield), with ~3.81 g of coke (~19.1%) and the rest as gaseous products (~19.2%). GC-MS analysis revealed enhanced production of light naphtha (LN), heavy naphtha (HN), and kerosene in the 400–450 °C range, with a clear temperature-dependent shift in product distribution. Structural analysis confirmed that cerium incorporation enhanced surface acidity, redox activity, and thermal stability, promoting deeper cracking and better product selectivity. Kinetics were investigated using an eight-lump first-order model comprising 28 reactions, with kinetic parameters optimized through a genetic algorithm implemented in MATLAB. The model demonstrated strong predictive accuracy taking into account the mean relative error (MRE = 9.64%) and the mean absolute error (MAE = 0.015) [MAE: It is the absolute difference between experimental and predicted values; MAE is dimensionless (reported simply as a number, not %). MRE is relative to the experimental value; it is usually expressed as a percentage (%)] across multiple operating conditions. The above findings highlight the potential of Ce-modified kaolinite-based catalysts for efficient atmospheric pressure VR upgrading and provide validated kinetic parameters for process optimization. Full article

Zeolites are widely used as solid acid catalysts and also as supports in complex multifunctional heterogeneous systems. In recent years, there has been an increase in the development of zeolite-based catalysts with hierarchical porosity combined with metal dopants (modifiers or catalysts). These modifications can significantly improve the catalytic characteristics of such materials. In this review, we discuss the application of hierarchically porous zeolites, including metal-doped ones, in catalytic reactions employed in the production and upgrading of liquid fuels, i.e., pyrolysis of biomass and polymeric wastes; conversion of alcohols to fuel hydrocarbons, aromatics and olefins; cracking and hydrocracking of polymeric wastes and hydrocarbons; and hydroisomerization. It is revealed that, in many cases, higher activity, selectivity and stability can be achieved for metal-doped hierarchical zeolites in comparison with parent ones due to control over the diffusion, surface acidity and coke deposition processes. Full article

Crude oil accounts for approximately 40% of global energy consumption, and the refining sector is a major contributor to greenhouse gas (GHG) emissions, particularly through the production of hard-to-abate fuels such as aviation fuel and fuel oil. This study disaggregates the refinery into its key process units to identify decarbonization opportunities along the entire production chain. Units are categorized into combustion-based processes—including crude and vacuum distillation, hydrogen production, coking, and fluid catalytic cracking—and non-combustion processes, which exhibit lower emission intensities. The analysis reveals that GHG emissions can be reduced by up to 60% with currently available technologies, without requiring major structural changes. Electrification, residual heat recovery, renewable hydrogen for desulfurization, and process optimization through digital twins are identified as priority measures, many of which are also economically viable in the short term. However, achieving full decarbonization and alignment with net-zero targets will require the deployment of carbon capture technologies. These results highlight the significant potential for emission reduction in refineries and reinforce their strategic role in enabling the transition toward low-carbon fuels. Full article

Addressing IMO 2020 compliance, this study investigates marine fuel oil production from hydrotreated residues, focusing on mitigating excessive total sediment potential (TSP) caused by over-hydrotreatment. This study systematically investigates the impact of blending ratios of Fluid Catalytic Cracking (FCC) slurry oil with Residue Desulfurization (RDS) heavy oil on TSP, colloidal stability, and asphaltene structure evolution. Techniques such as XRD, SEM, and XPS were employed to analyze the structural changes in asphaltenes during the TSP exceeding process. The results indicate that as the FCC slurry oil blending ratio increases, TSP in the blended oil initially rises and then decreases. The peak TSP value of 0.41% occurs at a 10% FCC slurry oil blending ratio, primarily due to high-saturation hydrocarbons in RDS heavy oil disrupting the colloidal stability of asphaltenes in FCC slurry oil. When the blending ratio reaches 25%, TSP significantly decreases to 0.09%, attributed to the solubilizing effect of high aromatic compounds in the FCC slurry oil on the asphaltenes. The ω(Asp)/ω(Res) ratio mirrors the TSP trend, and the colloidal solubilizing capacity of asphaltenes increases with the blending ratio. Asphaltenes in RDS heavy oil exhibit a spherical structure, whereas those in FCC slurry oil show a layered structure. The precipitated asphaltenes in the blends primarily result from the aggregation of asphaltenes in FCC slurry oil, with heteroatoms (N, S, O) mainly originating from RDS heavy oil asphaltenes. During the early stage of blending, TSP formation is dominated by FCC slurry oil asphaltenes, but increasing the aromatic content in the system can significantly reduce TSP. This work provides theoretical and technical support for optimizing marine fuel blending processes in petrochemical enterprises. Full article