Spent Catalysts Research Articles

Iron Chloride Vapor Treatment for Leaching Platinum Group Metals from Spent Catalysts

AbstractAn efficient and environmentally friendly recovery of platinum group metals (PGMs) from secondary sources is necessary to ensure a sustainable supply of PGMs. In this study, contact with FeCl2 vapor in the presence of metallic Fe was investigated as a useful pretreatment for leaching PGMs from spent automobile catalysts. Fe-PGM alloys were efficiently formed when Pt, Pd, and Rh wires and Rh2O3 powder were subjected to FeCl2 vapor treatment at 1050 K (777 °C) for approximately 40 min. Further, the leachability of the PGMs in spent automobile catalyst samples increased after a similar vapor treatment was applied. When the pulverized spent catalyst sample without pretreatment was leached with aqua regia at 333 K (60 °C) for 60 min, 88% of Pt, 91% of Pd, and 37% of Rh were extracted. Meanwhile, after vapor treatment at 1050 K, 98% of Pt, 97% of Pd, and 87% of Rh were extracted under the same leaching conditions. Thus, the pretreatment with FeCl2 vapor, followed by leaching, is a feasible and effective technique for recovering PGMs from spent catalysts. Graphical Abstract

Tuning of Nickel Content in High-Layered LiNi_xMn_yCo_zO_2 (NMC) from Spent Catalyst

Tuning of Nickel Content in High-Layered LiNi_xMn_yCo_zO_2 (NMC) from Spent Catalyst

Production of light olefins from methanol using catalytic fixed bed reactor with different catalytic bed composition

Methanol to olefin conversion has captured the attention of the industry as olefins are feed material to many polymer industries. In this work methanol conversion to olefins was investigated over beds of (i) physical mixture of metal oxides with ZSM-5 (PMB) and (ii) metal impregnated over ZSM-5 (MLB). ZSM-5 used in the current study was pre modified by boric acid treatment for modifying catalytic active site composition. Two different metals from alkaline series: calcium and magnesium & from transition metal series: iron and copper were selected. PMB studies were performed on 1:1 (by weight) metal oxides and BZSM-5 whereas for MLB studies, 10 % metal was loaded. Performance studies of the two different bed composition were performed at 500°C, 100 ml/min N2 flow with 1 g catalyst in a fixed bed reactor. 100 % conversion was obtained on MLB studies in presence of Cu, Mg and Fe whereas in PMB studies, 100 % conversion could be obtained over FeO+BZSM-5 bed. The order of olefins yield obtained was in the following order: BZSM-5 > Mg/BZSM-5 > Cu/BZSM-5 > CuO+BZSM-5 > CaO+BZSM-5 > Fe/BZSM-5 > FeO+BZSM-5 > CaO+BZSM-5 > MgO+BZSM-5. It was observed that maximum methane yield was obtained in presence of physical mixture. Gaseous products other than olefins with high composition of C1–C4 hydrocarbons were formed in presence of Mg and Ca whereas the metal impregnated modified-ZSM-5 produced higher content of olefins with Cu loaded catalysts in both bed composition. Metal impregnated catalysts as well as physical mixtures were characterized by BET, FTIR and XRD, FESEM for surface area, topology, crystallinity etc. Spent catalysts were characterized for coke deposition using TGA.

Study of the spent catalysts as internal curing agents on the hydration kinetics and microstructure development of ultra-high performance concrete (UHPC)

In this study, the effect of 5–30 % (by mass) of spent catalyst (SC) on the characteristics of ultra-high-performance concrete (UHPC) is investigated, including mechanical properties, volumetric stability, hydration kinetics, and microstructural development. Specifically, scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and low-field proton nuclear magnetic resonance spectroscopy (1H NMR) are employed to clarify the microstructures, while thermogravimetric analysis (TG), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS) are carried out to understand the phase variation. The results obtained show that the samples containing SC and additional water exhibit good mechanical properties, such as a 1.0 %-2.9 % higher compressive strength of UHPC with SC (5–15 %) and additional water compared to SC1 at 60 days. Additionally, SC can also improve the volumetric stability of UHPC. Moreover, the Ca/Si ratio of the hydration products decreases and the Al/Ca ratio increases with the enhancement of SC and additional water content. Furthermore, the water release effect of SC promotes the hydration of cement and pozzolanic reactions, leading to the generation of more hydration products and optimization of the pore structure and interfacial transition zone (ITZ) of UHPC in this study.

Hydrometallurgical Molybdenum Recovery from Spent Catalyst Using Tartaric Acid Derived from Agrifood Waste

Hydrometallurgical Molybdenum Recovery from Spent Catalyst Using Tartaric Acid Derived from Agrifood Waste

Recovery of Vanadium and Molybdenum from Spent Catalyst Using Amine Based Extractants by Solvent Extraction Technique

Recovery of Vanadium and Molybdenum from Spent Catalyst Using Amine Based Extractants by Solvent Extraction Technique

Improved Palladium Extraction from Spent Catalyst Using Ultrasound-Assisted Leaching and Sulfuric Acid–Sodium Chloride System

This paper presents a process for efficiently recovering palladium (Pd) from spent Pd/Al2O3 catalysts used for hydrogenation reactions, using ultrasound-assisted leaching (UAL). A system composed of H2SO4 and NaCl was investigated under ultrasound-enhanced conditions and compared to regular leaching methods to demonstrate the superiority of UAL. Single-factor experiments were conducted to determine the optimal conditions for leaching, which included an ultrasound power of 200 W, a liquid–solid ratio of 5:1, a leaching time of 1 h, a leaching temperature of 60 °C, H2SO4 concentration of 60%, and 0.1 mol of NaCl. The leaching rate under these conditions was found to be 99%. Additionally, kinetic analysis of the UAL process showed that the apparent activation energy of the Pd leaching reaction was 28.7 kJ/mol, and it was found that Pd leaching from spent catalysts was controlled by diffusion. The tailings were analyzed by SEM, revealing that during ultrasonic leaching, the specific surface area of the spent catalyst increased, the mass transfer rate of the solution was accelerated, the passivation film on the surface of the spent catalyst was peeled off, and a new reaction interface was formed. This improved the leaching rate of Pd and provided a new approach to efficiently leach precious metals such as Pd from spent catalysts.

An Investigation on Eco Friendly Self-Compacting Concrete Using Spent Catalyst and Development of Structural Elements

The theme of this initiative is "Waste to Wealth." Construction materials, particularly concrete, need to have better qualities, including strength, rigidity, durability, and ductility, because Oman's construction industry is expanding. Self-compacting concrete (SCC) has more benefits than regular concrete, including better workability. The major focus of this study is the C30-grade SCC for the control mix, spent catalyst (zeolite catalyst)-based SCC, and the development of the RC beam's flexural behavior employing control and spent catalyst-based SCC. The preliminary study and the main study are the two study outcomes included in this project. Preliminary research involves creating four mixtures with various dosages of 3%, 6%, 9%, and 12% in order to optimize spent catalyst in C30 grade concrete. All of the cubes undergo a 28-day curing test. The cubes' compressive strength is tested in order to establish the ideal dosage, which is 9%. Develop a C30 grade control modified design mix in accordance with SCC and optimize chemical admixtures such as superplasticizer (SP) at different dosages, like 2, 2.5, 3, and 3.5%, using various trials and tests (slump flow, L-box, J-ring, V-funnel, and U-box tests), as well as the optimized dosage of spent catalyst (SC). The main study includes six singly reinforced RC beams with dimensions of 750 (L)×100 (B)×150 mm (D) that were cast and tested in the laboratory. After a 28-day curing period, two specimens were placed under a two-point loading setup, with the remaining two samples receiving the optimum dosages of spent catalyst and superplasticizer. All of the beams were tested using a Universal Testing Machine (UTM) with a 1000 kN capability. From the preliminary study, partial substitution of cement in control concrete of grade C30 using spent catalyst (SC), it was found that the 9% optimum dosage produces greater compressive strength compared to other doses, which are almost 10% rises at 28 days of curing period. Based on a different test, it was discovered that the optimum dose of 3% SP gave closer agreement and satisfied the need for SCC as per the BS standard. The load-carrying capability of the SCC beams is almost 21.7% higher than that of the control beams. Comparing the SCC beams to the control beams, their deflection was reduced by about 26% at the same load level, and their ductility rose by almost 33%. Comparatively to the control beam, the stiffness of 21.6% of SCC also rises. According to test results, the SCC beam performs better in every way when superplasticizer and spent catalyst are used at the recommended dosage. Doi: 10.28991/CEJ-2023-09-05-08 Full Text: PDF

An environmentally friendly method for extraction of cobalt and molybdenum from spent catalysts using deep eutectic solvents (DESs).

There has been a substantially increasing demand for energy critical elements (ECEs) in recent years as energy-related technology has advanced rapidly. Spent catalysts are known as potential sources of ECCs such as Ni, Co, Mo, W, V, and rare earth elements. This study developed a novel environmentally friendly process for recovering cobalt and molybdenum from spent hydroprocessing catalysts using deep eutectic solvents (DESs). DESs based on p-toluenesulfonic acid achieved high metal extraction at 100°C and a pulp density of 20g/L for 48h which 93% of cobalt and 87% of molybdenum were dissolved. FT-IR and H-NMR analyses were conducted to determine whether hydrogen bonds form between p-toluenesulfonic acid-based DES components. Leaching kinetic models were also developed for DES systems. The experimental results were well-matched with the shrinking core models. The leaching controlling step of DES-1 was determined to be the diffusion through the product layer based on kinetic studies, with an activation energy of 22.56kJ/mol for Co and 29.34kJ/mol for Mo in DES-1. Similarly, the mixed control reaction with an activation energy of 38.09kJ/mol for Co and 31.48kJ/mol for Mo in DES-2 was found to control the leaching kinetic mechanism of the DES-2 sample.

Green extraction of pure ferromagnetic nickel from spent hydroprocessing catalysts via deep eutectic solvents

Spent catalysts can be extremely hazardous to the environment and human health if not properly managed. In this study, a novel environmentally friendly flowsheet based on deep eutectic solvents (DESs) was developed to efficiently recover nickel from spent hydroprocessing catalysts. The potential of eight different DES (binary and ternary) to leach Ni from two different spent catalyst hydroprocessing samples was evaluated. The p-toluenesulfonic acid-based DES-1 (PEG-400:PTSA) and DES-8 (ChCl:EG:PTSA) showed high nickel extraction (>90 %). The effect of time, temperature, and solid to liquid ratio on nickel extraction was investigated. Selective nickel extraction was obtained under the pulp density of 20 g/L, a temperature of 100 °C, and a leaching time of 48 hrs. The shrinking core models fitted well with the experimental results. The ferromagnetic face-centered cubic (FCC) nickel powder was produced successfully using the cementation method. This study establishes a novel green approach based on DES for recovering nickel from spent catalysts without any roasting or oxidative agent addition.

The Activity and Stability of Promoted Cu/ZnO/Al2O3 Catalyst for CO2 Hydrogenation to Methanol

Cu/ZnO/Al2O3 catalyst with the addition of tri-promoters (Mn/Nb/Zr) was investigated with respect to their catalytic activity and stability in a prolonged reaction duration in methanol synthesis. Spent catalysts were characterized using N2 adsorption-desorption, FESEM/EDX, TEM, N2O chemisorption, and XPS for their physicochemical properties. The catalyst longevity study was evaluated at two days, seven days, and 14 days at 300 °C, 31.25 bar, 2160 mL/g.hr GHSV, and H2:CO2 at 10:1. The CO2 conversion and methanol yield decreased by about 5.7% and 7.7%, respectively, when the reaction duration was prolonged to 14 days. A slight reduction in catalytic activity under prolonged reaction duration was found due to thermal degradation.

Alumina-supported cobalt catalysts in the hydrogenation of CO2 at atmospheric pressure

20 wt.% cobalt catalysts supported on pure and 5 wt.% silica-containing alumina have been prepared and characterized by X-Ray Diffraction, IR and DR-UV-vis-NIR spectroscopies and Field-Emission Scanning Electron Microscopy (FE-SEM). The presence of a cobalt-containing surface spinel phase Co3-xAlxO4 and, for the silica-containing sample, of a segregated Co3O4 phase is evident. These catalysts have been tested in CO2 hydrogenation at atmospheric pressure in steady state conditions in the temperature range 523–773 K. Both catalysts are active in CO2 hydrogenation to methane (methanation) and to CO (reverse Water Gas Shift, rWGS). CO2 hydrogenation activity is higher on freshly pre-reduced silica-free Co/Al2O3, while selectivity to methane is slightly higher on the silica-containing sample. Spent catalysts contain clustered or amorphous cobalt metal centers as active sites for methanation. The silica-containing catalyst shows slow deactivation in CO2 hydrogenation upon 13 h experiments, with quite stable or even slightly increasing rWGS activity and decreasing CH4 selectivity. This confirms previous data suggesting that, over cobalt catalysts, sites for methanation are metal centers prone to deactivation by carbon deposition. However, in contrast with what happens with unsupported and silica-supported cobalt catalysts, where deactivation is very fast, over these alumina-based catalysts carbon deposition and deactivation occur much more slowly. Sites for rWGS are unreduced cobalt centers which do not undergo such a deactivation phenomenon.

Recent Developments on Processes for Recovery of Rhodium Metal from Spent Catalysts

Rhodium (Rh) catalyst has played an indispensable role in many important industrial and technological applications due to its unique and valuable properties. Currently, Rh is considered as a strategic or critical metal as the scarce high-quality purity can only be supplemented by refining coarse ores with low content (2–10 ppm) and is far from meeting the fast-growing market demand. Nowadays, exploring new prospects has already become an urgent issue because of the gradual depletion of Rh resources, incidental pressure on environmental protection, and high market prices. Since waste catalyst materials, industrial equipment, and electronic instruments contain Rh with a higher concentration than that of natural minerals, recovering Rh from scrap not only offers an additional source to satisfy market demand but also reduces the risk of ore over-exploitation. Therefore, the recovery of Rh-based catalysts from scrap is of great significance. This review provides an overview of the Rh metal recovery from spent catalysts. The characteristics, advantages and disadvantages of several current recovery processes, including pyrometallurgy, hydrometallurgy, and biosorption technology, are presented and compared. Among them, the hydrometallurgical process is commonly used for Rh recovery from auto catalysts due to its technological simplicity, low cost, and short processing time, but the overall recovery rate is low due to its high remnant Rh within the insoluble residue and the unstable leaching. In contrast, higher Rh recovery and less effluent discharge can be ensured by a pyrometallurgical process which therefore is widely employed in industry to extract precious metals from spent catalysts. However, the related procedure is quite complex, leading to an expensive hardware investment, high energy consumption, long recovery cycles, and inevitable difficulties in controlling contamination in practice. Compared to conventional recovery methods, the biosorption process is considered to be a cost-effective biological route for Rh recovery owing to its intrinsic merits, e.g., low operation costs, small volume, and low amount of chemicals and biological sludge to be treated. Finally, we summarize the challenges and prospect of these three recovery processes in the hope that the community can gain more meaningful and comprehensive insights into Rh recovery.

Resurrection of the spent NiMo/Al2O3 catalyst for diesel hydrofining

Spent catalysts from the hydrofining process are hazardous wastes, while their appropriate utilization can also bring enormous environmental and economic benefits. Herein, a chemical resurrection method was developed to resurrect and recycle the industrial spent NiMo/Al2O3 hydrofining catalyst. The spent catalysts are calcined to remove the carbon deposit followed by the treatment with citric acid (CA) and ethylene glycol (EG). The results show that the calcination can also accelerate the aggregation and inerting of the active phase. However, the redispersion and reactivation of the inactive phases over the spent catalysts are realized through formation of metal complex with the citric acid, which weaken the interaction between Mo species and support. It increases reducibility of the Mo species and then improve the sulfurization degree of the resurrected catalyst. Besides, the average length of MoS2 is reduced while the stacking number is increased. The ethylene glycol further regulates the reducibility of Ni and Mo species to promote the formation of NiMoS phase with high activity instead of Ni3S2. Consequently, the average length of the MoS2 is reduced while the average stacking number of MoS2 and content of the NiMoS phase are increased over the resurrected catalyst compared with the spent catalyst. It recovers the hydrodesulfurization activity of the resurrected catalyst to a level higher than that over the spent and industrially regenerated catalyst.

Produced Water Treatment Using The Residue Catalytic Cracking (RCC) Spent Catalyst As Ceramic Filter Material Integrated With Reverse Osmosis (RO) System

Produced Water Treatment Using The Residue Catalytic Cracking (RCC) Spent Catalyst As Ceramic Filter Material Integrated With Reverse Osmosis (RO) System

The development of a techno-economic model for the assessment of vanadium recovery from bitumen upgrading spent catalyst

Spent catalyst from bitumen upgrading contains a substantial amount of vanadium. Recovering this vanadium can contribute to meeting the global demand. However, there are no studies on the economic feasibility of vanadium recovery plants, which is critical for decision makers. In this research, a techno-economic assessment of a vanadium recovery process was performed to bridge that gap. Data intensive process models were developed to understand the mass and energy balances of the vanadium recovery process. Capital and operating costs were estimated from material and energy balances. The recovery cost of vanadium was estimated using the developed techno-economic models, including the revenue for selling the co-products and by-products of the process. The economies of the scale and the effect of co-product and by-product selling price on the vanadium recovery cost were also studied. We found that for a plant capacity of 30,000 tonnes of spent catalyst per year, the vanadium recovery cost is $9.89/kg V2O5. For a market price of $12.00/kg V2O5, the minimum profitable capacity is about 22,400 tonnes of spent catalyst per year, and molybdenum trioxide is the co-product whose selling price has the most influence on the vanadium recovery cost. The results show that for spent catalyst generated in bitumen upgrading operations, the recovery of vanadium is potentially profitable considering the current vanadium market price. The developed information is useful for the decision makers in making investment decisions and policy formulation.

Review of modern scientific developments in the field of extraction of vanadium oxide from petrochemical catalysts

A review of the scientific and technical literature on hydrometallurgical methods for extracting highpurity vanadium oxide from spent catalysts in the petrochemical industry has been carried out. Currently, high-purity vanadium oxide (V2O5 ≥ 99.5%) is not produced in Russia. The main consumer of high-purity vanadium oxide is the rapidly developing production of vanadium-containing master alloys for the manufacture of titanium alloys. In the chemical industry, high-purity vanadium oxide is used to produce catalysts for the synthesis of phthalic and maleic anhydrides. One of the promising sources of vanadium is spent (deactivated) vanadium catalysts (SVC), in which the content of the valuable component in terms of pentoxide (V2O5) can reach 4–8%. It is much higher than in most processed ore raw materials. Spent catalysts are a secondary raw material, since during operation there is a loss of catalytic properties (activity, conversion, selectivity). After several cycles of regeneration, such a product is a subject of recycling to obtain valuable components. It should also be noted that there is an increase in demand for hydrotreating catalysts, which may cause an excess of spent catalysts in the future. In this regard, there is an urgent need to develop a highly efficient technology for processing catalysts in order to extract valuable components. The review of the scientific and technical literature shows that there are many methods for processing spent catalysts. The article describes the methods of acid, alkali, soda leaching, as well as the performance indicators of these processes. But the existing scientific developments in this area need further development in order to improve the efficiency of the vanadium oxide leaching process. The work was performed under the agreement between the National Research Technological University “MISiS” and JSC “Company Wolfram” (Moscow region, Russia) No. 0422-341 dated April 22, 2021, implemented with the financial support of the Ministry of Science and Higher Education of the Russian Federation under the Decree of the Government of the Russian Federation No. 218 dated 04/09/2010.

THE MANAGEMENT OF SPENT CATALYST IN RCC/FCC UNITS IN ASEAN REFINERIES

Catalytic cracking processes convert heavy feed- stock (heavy distillate, residue) into gasoline and light cycle stock for middle distillate components. Due to high impurity of feedstock and limited operating condition of catalyst regeneration, fresh catalyst must be added to replace a portion of spent catalyst continously, to maintain the activity of equilibrium catalyst in the reactor. Spent catalyst must be disposed properly so that it does not cause hazard or environmental concern. A survey was conducted on the management of spent catalyst in RCC/FCC unit in ASEAN refineries as an ASCOPE Technical Committee work programme for 1996. Indonesia was tasked as the Coordinator with the support of Member Countries. The Coordinator for each Member Country is listed in the Table 1. This paper discusses briefly catalytic cracking process, deactivation of cracking catalyst and the management of spent cata- lyst in RCC/FCC units

Kinetics of Ni, V and Fe Leaching from a Spent Catalyst in Microwave-Assisted Acid Activation Process.

Ni, V and Fe are the main contaminant metals that lead to the deactivation of the spent fluid catalytic cracking (SFCC) catalyst. In this work, the properties and distribution of Ni, V and Fe in the SFCC catalyst are investigated by employing EPMA-EDX, SEM and XPS techniques. The kinetics of Ni, V, Fe and Al leaching in organic and inorganic acids are studied under microwave heating. The EPMA-EDX results show that Fe and Ni mainly accumulate near the particle surface, while V eventually distributes throughout the catalyst particle. The XPS result suggests that the phase speciations of Ni in the SFCC catalyst are Ni, Ni2SiO4 and NiAl2O4, while Fe is present in a mixture of Fe3O4, Fe2O3 and Fe2SiO4. V is in the forms of V2O5 and VO2. Compared with oxalic acid, sulfuric acid has a better removal effect of contaminant metals, especially for Ni. The leaching kinetics results indicate that using either sulfuric acid or oxalic acid, the apparent activation energy of V is obviously lower than that of Fe and Ni, and the priority of the three contaminant metals in the removal effect is V > Fe > Ni. In addition, the leaching kinetics of contaminant metals in the microwave-assisted acid activation process are controlled by the surface chemical reaction control model.

Obtaining New Aluminium Water Clarification Coagulant from Spent Catalyst

Obtaining New Aluminium Water Clarification Coagulant from Spent Catalyst