Search Results (10)

Copper-containing sludge and spent petrochemical catalyst (SPC) were investigated for recovering palladium (Pd) and silver (Ag). Increasing the mixing ratio of alumina-based SPC leads to reduced recovery rates at 1500 °C. Specifically, as the SPC mixing ratio increases from 10% to 30%, the recovery rate of Pd and Ag sharply decreases to 62.1% and 91.0%, respectively. This is attributed to an increase in the slag viscosity as well as to the higher sulfur content in the metal phase by decreasing the CaO/Al₂O₃ ratio of the slag. An increase in the slag viscosity causes a decrease in the metal recovery, as it lowers the settling velocity of metal droplets, resulting in imperfect metal separation, i.e., an increase in physical loss. Additionally, the presence of sulfur at the slag–metal interface was found to reduce interfacial tension, facilitating the entrapment of copper droplets within the slag. This further hindered phase separation and contributed to an increase in physical loss. This study highlights that physical loss is more serious in metal recovery rather than chemical loss, which is dependent on the thermochemical solubility of the target metals in the slag. The results emphasize the need for the precise control of slag properties to maximize the metal recovery processes in conjunction with a mitigation of CO₂ emissions. Full article

Catalytic combustion is an effective strategy for alleviating volatile organic compounds (VOCs), including hydrocarbons and aromatic compounds, mostly derived from the petrochemical and pharmaceutical industries. We employed Pd/Al₂O₃ as a catalyst for combusting aromatic VOCs via hydrogen catalytic combustion. It differs from conventional approaches that do not necessitate additional electric heating. Briefly, when hydrogen (H₂) is introduced below its lower explosive limit of 4% on the Pd/Al₂O₃ catalyst, it completely oxidizes important aromatic VOCs like benzene, toluene, ethyl benzene, and xylene to carbon dioxide and water. The catalytic performance of the integrated system remains stable even after long-term use. Therefore, hydrogen co-combustion on the Pd/Al₂O₃ catalyst can provide onsite heating for a facility without needing external electric heat. The catalytic performance shows no significant dependence on the sizes of Pd nanoparticles in both fresh and spent conditions, as demonstrated by XRD, XPS, and STEM analyses. Therefore, renewable green hydrogen can effectively reduce aromatic VOC pollutants, providing a more energy-efficient alternative. Our findings suggest that this integrated process is promising for converting aromatic VOCs into carbon dioxide and water without electric heating. Full article

Zeolite Socony Mobil-5 (ZSM-5) is a commonly spent catalyst in the petrochemical industry; and phosphogypsum (PG) is a kind of industrial waste produced in the process of phosphoric acid production. The environmental issues caused by these two solid wastes are urgent and thus sustainable methodologies are required to dispose of and reutilize them. In this research, the waste ZSM-5 and waste PG were used to prepare a novel autoclaved aerated concrete. The effects of the different contents of disused ZSM-5 on the microstructures and performance of the PG-based AAC were determined. The results showed that the compressive strength and bulk density of the DZ4 sample were 2.6 MPa and 520 kg/m³, respectively. This study provides a novel and green approach to the reutilization of both waste PG and spent ZSM-5. Full article

The article describes the technology of molybdic acid recovery from spent petrochemical catalysts (HDS) developed and implemented in industrial activity. HDS catalysts contain molybdenum in the form of MoO₃ and are used for the hydrodesulfurization of petroleum products. After deactivation, due to the impurities content in the form of sulfur, carbon and heavy metals, they constitute hazardous waste and, at the same time, a valuable source of the Mo element, recognized as a critical raw material. The presented technology allows the recovery of molybdic acid with a yield of min. 81%, and the product contains min. 95% H₂MoO₄. The technology consisted of oxidizing roasting of the spent catalyst, then leaching molybdenum trioxide with aqueous NaOH to produce water-soluble sodium molybdate (Na₂MoO₄), and finally precipitation of molybdenum using aqueous HCl, as molybdic acid (H₂MoO₄). Industrial-scale testing proved that the technology could recover Mo from the catalyst and convert it into marketable molybdic acid. This proves that the technology can be effectively used to preserve molybdenum. Full article

Spent fluid catalytic cracking catalysts (S-FCC-Cs) constitutes a fraction of the hazardous solid waste generated in the petrochemical industry. The resource application of S-FCC-Cs remains a challenge. This study aims to explore utilizing S-FCC-Cs in asphalt mortar as a means to enhance resource utilization. Five different S-FCC catalysts were used as substitutes for mineral powder in the asphalt slurry at varying proportions. The high-temperature rheology of the resulting spent FCC catalyst-modified asphalt slurry was analyzed using temperature scanning tests and multiple stress creep recovery (MSCR) tests conducted at different temperatures and substitution doping levels. As the proportion of alternative doping increased, both the phase angle and irrecoverable creep flexibility decreased, while the absolute values of the rutting factor, deformation recovery rate, and irrecoverable creep flexibility difference increased. Moreover, as the temperature rose, the phase angle increased while the rutting factor decreased. The inclusion of an alternative admixture significantly improved the high-temperature performance of the asphalt mastic. This improvement was attributed to several factors, including the increase in the elastic component, enhanced deformation resistance, and improved deformation recovery. While the high-temperature performance of spent FCC catalyst-modified asphalt mastic gradually declined with increasing test temperature, all performance indices remained superior to those of limestone mineral powder asphalt mastic. In addition, the asphalt mortar modified by S-FCC-C JX with a surface area and hydrophilic coefficient of 105 m²/g and 1.026, respectively, exhibited the best rutting resistance and resilience performances among the five mortars, suggesting that the two factors co-affected the high-temperature rheological properties of S-FCC-C asphalt mortar. Considering stress sensitivity, it is more advantageous in improving the high-temperature deformation resistance of asphalt slurry at the JX dosage of 20%. These research findings offer valuable guidance for the application of S-FCC catalysts in asphalt pavement. Full article

The significant reduction in CO₂ emissions arising from the cementitious composites industry is one of the highest priorities for the construction sector’s movement towards climate neutrality and sustainable development. One of the approaches to cope with this issue is to partially substitute cement with supplementary cementitious materials. Recently, various oil refinery wastes (ORW) have attracted researchers’ attention in terms of being investigated for such an application. As such, the present paper shows the preliminary results of investigations conducted on cement pastes with the addition of a spent fluid catalytic cracking catalyst derived from a Polish oil refinery company. It is worth mentioning that the incorporation of ORW in cementitious composites might enable the production of more environmentally friendly construction materials without sacrificing quality, whilst, simultaneously providing an opportunity for recycling petrochemical wastes. Full article

Fluid Catalytic Cracking (FCC) has traditionally been a key refining process in generating transportation fuels. Recently, the focus on FCC has been further intensified as it plays an increasingly important role in the generation of key building blocks for the petrochemical industry. Nickel is considered as one of the most challenging contaminants in FCC and originates from Ni-containing compounds in petroleum fractions, not only during unit operation but also in handling of the equilibrium and spent catalysts. Despite this critical role it plays throughout the complete lifecycle of an FCC catalyst, the nature of Ni is not yet well understood at various stages of its journey after depositing on the catalyst surface. The main objective of this contribution is the qualitative and quantitative identification of the various possible phases of Ni that are usually present in an equilibrium FCC catalyst (Ecat). A series of conventional and advanced analytical techniques have been employed, including XRF, ICP-AES, PXRD, FT-IR, UV-Vis-NIR, SEM-EDS, TEM/HRTEM and STEM/EXDS, XPS, RAMAN and TPR-H₂, on prototype Ni-impregnated SiO₂, Al₂O₃ and USY zeolite samples, Ni-impregnated and lab-deactivated FCC samples, and equilibrium FCC catalysts obtained from different refineries. Detailed analysis of the obtained results on the basis of background information, showed the strengths and weaknesses of the various methods. It was shown that powder x-ray diffraction (pxrd) can be effectively used for the quantitative determination of the NiO (bunsenite) phase at levels representative of equilibrium FCC catalysts. A comparison of conventional versus boron-based Ni-passivation is presented. It was shown that catalysts from boron-based technology (BBT) can keep Ni at a less-reducible state, effectively hindering its deleterious role in FCC operations. Full article

Spent fluid catalytic cracking catalysts (FCC catalysts) produced by the petrochemical industry are considered to be environmentally hazardous waste, and precious metals and heavy metals deposited on the surface make them difficult to treat. Even so, these catalysts retain some of their activity. The pyrolysis of waste tires is considered to be one of the most effective ways to solve the fossil fuel resource crisis, and this study attempts to catalyze the pyrolysis of waste tires using spent catalysts to increase the value of both types of waste. FCC catalysts reduced the activation energy (E) of waste tire pyrolysis. When the catalyst dosage was 30 wt.%, the E of tread rubber decreased from 238.87 kJ/mol to 181.24 kJ/mol, which was a 19.94% reduction. The E of the inner liner decreased from 288.03 kJ/mol to 209.12 kJ/mol, a 27.4% reduction. The spent catalyst was more effective in reducing the E and solid yield of the inner liner made of synthetic rubber. It should be emphasized that an appropriate increase in the heating rate can fully exert the selectivity of the catalyst. The catalyst could also be effectively used twice, and the optimum ratio of catalyst/waste tires was about 1/4.5. Compared with specially prepared catalysts, it is more cost-effective to use such wastes as a catalyst for waste tire pyrolysis. Full article

Palladium (Pd) and platinum (Pt) are extensively used as catalysts in the petrochemical and automotive industries, and due to high demand for them on the market, their recycling from spent supported catalysts is clearly needed. To assess the content of Pd and Pt in catalysts in order to establish their commercial value or to evaluate the recovery efficiency of technologies used for recycling, reliable analytical methods for determination of these elements are required. Spectrometric methods, such as inductively coupled plasma optical emission spectrometry (ICP-OES) and graphite furnace atomic absorption spectrometry (GFAAS) are powerful tools that can be employed for the determination of Pd and Pt in various sample matrices. However, these methods allow only the injection of liquid samples. In this regard, the digestion of solid sample by microwave-assisted acid extraction procedures at high pressures and temperatures is often used. In this study, a microwave acid digestion method was optimized for the extraction of Pd and Pt from spent catalysts, using a four-step program, at a maximum 200 °C. The resulting solutions were analyzed using ICP-OES, at two different wavelengths for each metal (Pd at 340.458 and 363.470 nm, and Pt at 265.945 and 214.423 nm, respectively) and using GFAAS (Pd at 247.64 nm, Pt at 265.94 nm). Five types of spent catalyst were analyzed and the standard deviations of repeatability for five parallel samples were less than predicted relative standard deviations (PRSD%) calculated using Horvitz’s equation for all the analyzed samples. Full article

This research addresses the replacement of cement by an untreated waste from the petrochemical industry. The effects of partial replacement of cement by spent fluid cracking catalyst (SFCC) on properties of mortar were determined. In this study, a series of mortar mixes was prepared with replacement ratios of 0%, 3%, 6%, and 12%. Furthermore, performance enhancing factors such as SFCC treatment or use of plasticizers were avoided. Workability, compressive strength, and durability related properties were assessed. An improvement regarding resistance to chloride penetration was observed, as well as that, when curing in salt water, the use of SFCC may be advantageous regarding compressive strength. Full article