Spent Fluid Catalytic Cracking Catalyst Research Articles

A comparative study of the extraction of metals from the spent fluid catalytic cracking catalyst using chemical leaching and bioleaching by Aspergillus niger

The present study evaluates biopotential of Aspergillus niger and chemical potency of strong organic and inorganic acids to leach out Al, Fe, Ti, Ni, V from spent fluid catalytic cracking catalyst (SFCCC). One-step bioleaching (OSBp) and spent medium bioleaching (SMB) of metals at 1%, 3% and 5% pulp densities by Aspergillus niger was investigated. Leaching efficiency was found to be maximum at 1% pulp density and decreased as the pulp density increased to 5%, this is perhaps due to the inhibitory effect of some metals existing in SFCCC. The maximum amount of Al, Fe, Ti, Ni, and V leached from SFCCC are 1388 mg/L, 28 mg/L, 6 mg/L, 2 mg/L and 8 mg/L of leaching medium respectively. Biologically produced leaching agents other than citric, gluconic and oxalic acids produced by Aspergillus niger solely contributed to 50%, 32%, and 42% of Al, Ti and V leaching efficiencies respectively. The acidic pH in OSBp suggests acidolysis as the leading leaching mechanism. The citric acid is the chief leaching agent produced by Aspergillus niger in the presence of SFCCC while gluconic acid dominated in SMB (in the absence of SFCCC). OSBp yielded higher leaching efficiencies of all the metals compared to SMB. OSBp dominated Al, Ti, and V leaching compared to all organic and inorganic acid leaching. While OSBp of Fe was comparable to inorganic acid leaching and oxalic acid leaching is suggested for Ni leaching. The competitive Al, Ti, V and Fe leaching and being environmentally friendly, OSBp of metals from SFCCC by Aspergillus niger is recommended.

Experimental Study on Spent FCC Catalysts for the Catalytic Cracking Process of Waste Tires

Research on the synergistic high-value reuse of waste tires and used catalysts in spent fluid catalytic cracking (FCC) catalysts was carried out in this study to address the serious ecological and environmental problems caused by waste tires and spent FCC catalysts. The experiment, in which a spent FCC catalyst was applied to the catalytic cracking of waste tires, fully utilized the residual activity of the spent FCC catalyst and was compared with a waste tire pyrolysis experiment. The comparative experimental results indicated that the spent FCC catalyst could improve the cracking efficiency of waste tires, increase the output of light oil in pyrolysis products, and improve the quality of pyrolysis oil. It could also be used for the conversion of sulfur compounds during cracking. The content of 2-methyl-1-propylene in catalytic cracking gas was found to be up to 65.59%, so a new method for producing high-value chemical raw materials by the catalytic cracking of waste tires with spent FCC catalysts is proposed.

Bioleaching of Al from spent fluid catalytic cracking catalyst using Aspergillus species

Bioleaching uses biodegradable organic acids, thereby making the process environmental friendly as compared to chemical leaching. In this work, bioleaching of aluminium (Al) metal from spent catalyst was investigated by using three Aspergillus strains (A. niger, A. foetidus, and A. carbonarius). Bioleaching was performed in batch culture mode at different loading densities of spent catalyst (i.e., 0.4%, 0.8% and 1.2% (w/v)). The highest Al leaching efficiency of 88.43% was obtained at 0.8% ((w/v)) catalyst loading using A. foetidus, further increase in the catalyst loading decreased the efficiency. In addition to this, molasses was used as a carbon source (low-cost) at various concentrations for bioleaching of spent catalyst and the results were found to be significant at 40 g/L sugar concertation with 60% bioleaching efficiency. Overall, this study indicates that A. foetidus have the potential for leaching of Al from spent catalysts. Therefore, present research findings suggested that, instead of using mineral acids, organic acids (biodegradable) usage for metal leaching process is highly reliable and eco-friendly as well.

Synthesis of zeolites from spent fluid catalytic cracking catalyst

The present paper describes the experimental tests for the recycling of fluid catalytic cracking catalysts (FCCCs). The process aims at the recovery of cerium (Ce) and lanthanum (La) as well as the reuse of the leaching solid residue that represents the actual problem in terms of global amount landfilled every year. Landfilling is still the main choice for the handling of such catalysts. This novel process proposes an alternative recycling approach that leads to the production of synthetic zeolites, that have several industrial applications. FCCC was leached by 1.5 mol/L of HNO3, HCl and H2SO4 solutions at 80 °C, for 2 h with a solid to liquid ratio of 20 %wt, and the two rare earth elements were recovered by precipitation with an overall yield in the range 70–80%. The solid residues from the leaching stage were used as the base material for the synthesis of the zeolites by means of a combined thermal-hydrothermal treatment. The characterization of the zeolites demonstrated that the Na-A phase was predominant over the Na-X phase. The zeolites were tested as sorbent material for CO2 separation from CH4, in order to simulate the upgrading of biogas to biomethane. The maximum adsorption rate of CO2 was 0.778 mol CO2/kg of zeolite at 3 bar, with a resulting CH4 recovery of 62% and 97 %vol as purity. Since the results in adsorption of CO2 were not satisfying, the same zeolites were used to remove heavy metals from a synthetic wastewater solution containing three metals. Equilibrium and kinetic models were also developed in order to describe the adsorption process. The maximum adsorption load was calculated by the Langmuir isotherm and resulted to be 24–32 mg/g for Ni, 52–60 mg/g for Zn and 122–181 mg/g for Cu. The results also showed that the kinetics of the adsorption process is almost fast, as after 1 h at least 95% of zinc and copper were removed, whereas the kinetics of nickel was slower for all the three zeolites. As a conclusion, the zeolites are more efficient in metal adsorption than CO2 capture, but other applications will be tested in the future.

Leaching of nickel and vanadium from the spent fluid catalytic cracking catalyst by reconnoitering the potential of Aspergillus niger associating with chemical leaching

The current study evaluates the bio-potential of Aspergillus niger to leach out Nickel, Vanadium from spent fluid catalytic cracking catalyst (SFCCC) and is compared with chemical leaching by organic and inorganic acids. Bioleaching efficiency of Nickel at 1, 3 and 5% pulp densities were 16.5, 13 and 8% respectively. The percentage Vanadium leaching at same pulp densities was found to be 55, 37 and 27% respectively. Leaching efficiency decreased with increase in pulp density which may be due to the toxic effects of metals present in the SFCCC. The spent medium bioleaching resulted in 4.7% Nickel and 18% Vanadium leaching, which is far less than one step bioleaching (OSB). This may be attributed to high citric acid production (100 mM) in OSB which perhaps be triggered by key metals of SFCCC. The acidic pH of the medium suggests acidolysis as the principal leaching mechanism. Oxalic acid was found to be the dominant leaching agent for Nickel, while for Vanadium, OSB took over. The leaching of Nickel was found to be only due to predominant acids produced by Aspergillus niger. Biogenically produced leaching agents apart from predominant acids accounted for 40% of Vanadium leaching. It is evident that removal of volatile carbonaceous material from SFCCC improved Nickel leaching by three folds.

A bio-hydrometallurgical approach towards leaching of lanthanum from the spent fluid catalytic cracking catalyst using Aspergillus niger

Spent fluid catalytic cracking catalysts (SFCCC) are the wastes generated from oil refineries, which accounts for 700,000–900,000 metric ton/year worldwide. Lanthanum, a short-term near critical element is the key component of SFCCC and accounts for 8170 mg/Kg. The current research intends to recover lanthanum from SFCCC by Aspergillus niger and compare the results with strong organic and inorganic acid leaching. Batch studies of one-step bioleaching (OSB) at 1, 3 and 5% pulp densities yielded 63%, 52%, and 33% lanthanum recovery, respectively. The decrease in leaching efficiency with an increase in pulp density may be attributed to the inhibition effect of SFCCC on A. niger. Citric acid was the main lixiviant produced by A. niger, whose production was triggered by SFCCC at ≤1% pulp density. Acidic pH of the leaching medium suggested acidolysis as the key mechanism. Cell-free spent medium bioleaching (cfSMB) resulted in 30.8% leaching recovery, which was significantly less than the OSB. In chemical leaching, sulfuric and nitric acid showed 38% efficiency whereas oxalic acid showed 5% recovery. Hydrochloric, citric and gluconic acids resulted in 68%, 65%, and 64% leaching recoveries, respectively, which is nearly the same as that offered by OSB. OSB being the greener process, suggested for lanthanum leaching from SFCCC over other processes.

Investigation of Entrance and Wall Dynamics of the High-Flux Gas-Solid Riser Using Statistical Analysis of Solids Concentration Signals

Statistical analysis of the entrance and wall dynamics of a high-flux gas-solid riser was done using solid concentration time series data collected from a 76 mm internal diameter and 10 m high riser of a CFB system with a twin-riser operated at 4.0 to 10.0 m/s gas velocity and 50 to 550 kg/m2s solids flux. Spent fluid catalytic cracking catalyst particles with 67 μm mean diameter and density of 1500 kg/m3 together with 70% to 80% humid air was used. Solid concentration data were analysed using code prepared using FORTRAN 2008 to get statistical parameters and plot their profiles. Results obtained show that the gas-solid suspension flow in the riser is dominated by low solid concentration in the centre region and high solid concentration in the wall region which forms a core-annulus flow structure. The mean solid concentration in the wall region decreases with riser height from the dense bottom section to less dense in the fully developed flow section at the top of the riser. The gas-solid suspension flow in the centre region is dominated with uniform flow structure while the wall region is dominated with high fluctuations in solid concentration. Further, it was found that the entrance and developing flow sections of the riser exhibit high flow non-uniformities than the fully developed flow section of the riser. The flow non-uniformities in the entrance and developing flow section increase with increase in superficial gas velocity at constant solid flux. The wall region, from the entrance to the top sections of the riser along the axial direction exhibits both dilute and dense suspension flow.

Synthesis, characterization and activity performance of nickel-loaded spent FCC catalyst for pine gum hydrogenation.

A Ni-based catalyst supported over a spent fluid catalytic cracking (FCC) catalyst was prepared by a wet impregnation method. The catalytic characteristic was investigated in pine gum hydrogenation. Optimum conditions for catalyst preparation were obtained as: 15% Ni loading, 723 K calcination temperature, and 723 K reduction temperature for 2.5 h. The characterization results indicate that the specific surface area of the spent catalyst increased from 65.70 m2 g−1 to 67.78 m2 g−1 after calcination. The H2-TPR profile of the spent FCC catalyst exhibited two reduction peaks at 1123 °C and 670 °C. The TG curves showed that the second and third steps occur at 440 K and 550 K, respectively, having a total weight loss of 16%. The NiO grains possess rhombus particles on the surface or between the layers of the supported NiO catalyst. After activation in H2 flow, the metallic Ni loads on the support with no covalent bond between them. The NH3-TPD results indicated that the spent FCC catalyst held an obvious distribution of weakly acidic sites, and the acid sites became stronger after loading the catalyst with Ni. The hydrogenation products of pine gum were identified by GC-MS and a reaction mechanism was proposed. This study demonstrated its cost-effectiveness, environment-friendly nature and that the utilization of a spent FCC catalyst can be effectively applied as an alternative approach to pine gum hydrogenation on an industrial level.

Adsorption and mechanistic study for phosphate removal by magnetic Fe3O4-doped spent FCC catalysts adsorbent

The waste materials utilization has attained increasing attention due to the generation of a large number of spent materials. In the current study, a practical magnetic adsorbent (Fe3O4-doped spent Fluid Catalytic Cracking catalysts, abbreviated as FCCx@(Fe)y-O) was prepared, liable to be separated. The batch experiments were employed to investigate the phosphate removal behavior. The findings of this study demonstrated that FCC4@(Fe)1-O exhibited the best phosphate removal performance among the adsorbents (FCCx@(Fe)y-O), attributed to rough surface layer, i.e., composed of active sites. The various characterizations results revealed that the adsorption behavior of FCC4@(Fe)1-O followed the inner-sphere adsorption based on ligand exchanges mechanism. Furthermore, OH− played an important role in the adsorption process. Minor effects were showed on the phosphate removal in the experiments of commonly coexisting anions, except CO32− and SiO32−. The above findings affirmed that FCC4@(Fe)1-O was a suitable adsorbent for phosphate removal in the practical application.

Investigation of phosphate adsorption from an aqueous solution using spent fluid catalytic cracking catalyst containing lanthanum

A spent fluid catalytic cracking (FCC) catalyst containing lanthanum (La) was used as a novel adsorbent for phosphorus (P) in simulated wastewater. The experiments were conducted in a batch system to optimize the operation variables, including pH, calcination temperature, shaking time, solid-liquid ratio, and reaction temperature under three initial P-concentrations (C0 = 0.5, 1.0, and 5.0 mg/L). Orthogonal analysis was used to determine that the initial P-concentration was the most important parameter for P removal. The P-removal rate exceeded 99% and the spent FCC catalyst was more suitable for use in low P-concentration wastewater (C0 <5.0 mg/L). Isotherms, thermodynamics and dynamics of adsorption are used to analyze the mechanism of phosphorus removal. The results show that the adsorption is an endothermic reaction with high affinity and poor reversibility, which indicates a low risk of second releasing of phosphate. Moreover, chemical and physical adsorption coexist in this adsorption process with LaPO4 and KH2PO4 formed on the spent FCC catalyst as the adsorption product. These results demonstrate that the spent FCC catalyst containing La is a potential adsorbent for P-removal from wastewater, which allows recycling of the spent FCC catalyst to improve the quality of water body.

Microwave intensified synthesis of Zeolite-Y from spent FCC catalyst after acid activation

A novel microwave heating process for the synthesis of zeolite-Y from spent fluid catalytic cracking (SFCC) catalyst has been proposed in this work. The SFCC catalyst is firstly activated in microwave field by acid solution and then used as an aluminum source for the synthesis of zeolite-Y. The activation effect of hydrochloric acid and oxalic acid on the SFCC catalyst, and the synthesis effects of zeolite-Y production from the activated SFCC catalyst under microwave are studied by ICP, XRD, SEM, and N2 sorption studies. The results show that microwave-assisted acid activation process can facilitate the formation of the active γ-Al2O3 and as well enhance the crystallinity of zeolite-Y in the SFCC catalyst, which is beneficial for the synthesis of zeolite-Y. Compared with the inactivated SFCC catalyst, the activated SFCC catalyst has a larger specific surface area and a lower contaminated metal content. The specific surface areas of SFCC catalyst after activation by hydrochloric acid and oxalic acid are 197.1 and 113.6 m2/g, respectively, indicating better activation by hydrochloric acid compared to oxalic acid in the microwave field. The results demonstrate that increasing the synthesis temperature and prolonging the crystallization time favor the growth of zeolite-Y crystal particles, however, zeolite-Y partially transforms into zeolite-P. The priority of different aluminum sources in zeolite-Y synthesis is: hydrochloric acid activated SFCC catalyst > oxalic acid activated SFCC catalyst > inactivated SFCC catalyst. The zeolite-Y having a particle size range of 0.3–1 μm is successfully synthesized from the activated SFCC catalyst at 100 °C for 2 h under microwave at 2 kg/cm2 pressure and 1000 W power.

Hydrothermal synthesis of plugged micro/mesoporous Al-SBA-15 from spent fluid catalytic cracking catalyst

Abstract Plugged Al-SBA-15 with combined meso and microporosity was successfully hydrothermally synthesised from spent fluid catalytic cracking catalyst (sFCCc) as a single silicon and aluminium source. Al-SBA-15 and the sFCCc were comparatively characterised by X-ray diffraction, N2 adsorption-desorption measurements, transmission electron microscopy, and X-ray fluorescence. The results show that highly ordered hexagonal SBA-15 was successfully prepared, and its N2 adsorption-desorption isotherms present a two-step desorption branch with a pore-blocking channel feature. This finding provides a new approach to simultaneously reduce the production and increase the high-value utilisation of sFCCc.

Kinetics and Thermodynamics of Adsorption Process Using A Spent-FCC Catalyst

Adsorption is potentially an attractive technique for the treatment of wastewater containing dyes. In the present work, spent fluid catalytic cracking catalyst (SFCC), a petroleum refinery waste was explored as a novel adsorbent and report its adsorption capability for the first time in the literature. Batch adsorption studies were carried out to remove methylene blue (MB) dye using SFCC. The equilibrium data was modeled using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models. Also, the van’t Hoff equation was used to obtain the thermodynamic contributions of the process. Results show that the plot of intraparticle diffusion model (considering only film diffusion) has less R2 value (0.887); it seems that the plot is nonlinear. Hence, the data points were represented by a double linear set of equations (lines) considering both pore &amp; film diffusion. In the first straight line, the sudden increase in slope signifies that the dye molecules were transported to the external surface of the adsorbent through film diffusion. The second straight line signifies that the dye molecules diffused through the pores. The portion which does not pass through the origin indicates that the pore diffusion is the only rate-determining step for the transport of MB onto SFCC.

Synthesis and Characterization of Zeolites from Spent FCC Catalysts

Fluid catalytic cracking is one of the major secondary conversion process in petroleum refinery. Nowadays, the spent fluid catalytic cracking catalysts (FCCCs) are disposed of in landfill or stocked for a long period. Environmental risks and lack of space suggest that the management of FCCCs needs to be reviewed. The FCC catalysts contain about 3-3.5 %wt. of rare earth (RE) oxides; rare earth elements (REEs) are important for stabilization of the matrix of FCC catalysts. The main challenge is to develop an efficient process based on recovery of REEs and reuse of the solid leaching residue for some applications. In this paper a new process is proposed to recover cerium and lanthanum from FCCCs combined with reuse of the leaching solid residue for the production of synthetic zeolites. Three different zeolites were synthesized by using the solid residues from hydrochloric, nitric and sulfuric acid leaching. The chemical and physical properties of zeolites were characterized by different spectroscopic techniques including Scanning Electron Microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) for evaluating the surface morphology. The X-Ray Diffraction (XRD), the Brunauer–Emmett–Teller (BET) and Infrared Spectroscopy (FT-IR) analyses were used to characterize the structure of such zeolites. In addition, the X-ray Fluorescence (XRF) was used to identify the chemical composition. Zeolite is a solid porous material widely used as adsorbent in different processes, particularly applied to wastewater treatments. In this paper, adsorption of heavy metals onto zeolites were investigated by Inductively Coupled Plasma - Optical Emission Spectroscopy (ICP-OES). The best results in terms of metal removal were achieved by the zeolite synthesized from the sulfuric acid leaching residue.

Towards efficient extraction of La(III) from spent FCC catalysts by alkaline pre-treatment

In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFCC) catalysts per year. The recovery of rare earth metals (La(III), Ce(III),…) contained in SFCC catalysts using acid leaching process has attracted much attention of scientific community. In this study, the effect of alkaline pre-treatment of spent catalysts prior to the acid leaching process on the leaching yield of La(III) was investigated. The results showed that alkaline pre-treatment caused zeolite destruction, which had a positive effect on the leaching of La(III). High leaching yields of La(III), 80% and 86%, were achieved when the SFCC catalysts were pre-treated with NaOH and NH3, respectively, before leaching with 2 M HNO3 solution at 50 °C. These results were comparable with the one obtained from the sample that was leached by 7 M HNO3 at 50 °C without the initial alkaline pre-treatment. NH3 pre-treatment significantly enhanced the zeolite destruction in the SFCC catalysts and increased La(III) leaching yield compared to the NaOH pre-treatment. It is likely due to NH3 interactions with contaminant metals (e.g. Ni, V, and Fe), which were deposited on catalysts during cracking process.

Vanadium poisoning of FCC catalysts: A quantitative analysis of impregnated and real equilibrium catalysts

Amongst the contaminant transition metals Fe, Ni, V that deposits onto the fluid catalytic cracking (FCC) catalyst and promote unwanted secondary reactions, vanadium is the most deleterious one because not only acts as undesired dehydrogenation site but also migrates deeper inside the catalyst particles under the FCC regeneration conditions, stabilizing in different phases that attack the crystalline structure of the catalyst, thus resulting in its irreversible loss of activity. The mechanisms through which vanadium affect the catalyst during its use in the FCC process remain under debate and the accurate determination of the chemical species involved and of their concentration is of paramount importance for the investigations in this field. In this work, a quantification methodology for contaminant vanadium in FCC catalysts was developed based on X-ray fluorescence (XRF) and electron paramagnetic resonance (EPR). A commercial FCC catalyst was artificially contaminated with vanadium at different loads by pore volume impregnation with aqueous vanadyl sulfate solution, in the presence or not of a complexing agent, followed by steam deactivation at 788 °C/5 h, and the samples were compared to spent FCC catalysts from different Brazilian refineries. It has been shown that EPR is a very sensitive and reliable technique to quantify vanadyl ions (V4+) in FCC catalysts while lower valence states such as V3+ have not been detected in any of the samples studied. Vanadyl ions (VO2+) deposited onto the catalyst are mostly oxidized to higher valence state species and the extent of this oxidation in equilibrium catalysts from FCC units was calculated and related to the combustion mode at which the FCC regenerators operate. The artificial vanadium contamination and deactivation protocol adopted in this work resulted in a proportion of V4+/Vtotal of nearly 10%, similar to that of equilibrium catalysts sampled from FCC units with full combustion regeneration. The present study brings a new interpretation for the EPR signal detected as a broad unstructured line, with evidences of some vanadium existing as a ferri-/ferromagnetic surface phase in the catalyst particles, likely formed by induced oxygen vacancies during reaction (reducing atmosphere) and quite resistant to the regeneration step.

Production of high purity rare earth mixture from iron-rich spent fluid catalytic cracking (FCC) catalyst using acid leaching and two-step solvent extraction process

Acid leaching and a two-step solvent extraction procedure were developed to produce high purity mixture of La and Ce from iron-rich spent FCC catalyst discharged from Dzung Quat refinery (Vietnam). Acid leaching of the spent catalyst with 2M HNO3 and a solid-to-liquid ratio of 1/3 at 80 °C in 1 h dissolved almost 90% of La while 12% of Al and 25% of Fe were transferred to the leachate. The extraction of RE metals and main impurities such as Al and Fe by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) was investigated. Experiments showed that it was necessary to remove Fe before extracting RE and the optimum extraction conditions for a high recovery of RE while 0% of Al extraction were pH-1, contact time=10min, and D2EHPA/TBP volume ratio= 4: 1. At these conditions, the extraction yields of La(III) and Ce(III) were 72% and 89%, respectively. A two-step solvent extraction was developed to achieve a high purity of RE mixture, which included (1) the removal of impurity Fe by 25% (v/v) diisooctyl phosphinic acid (DiOPA) in n-octane for 140 min, (2) the extraction of rare earths by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) in n-octane for 10 min without the need for adjusting the pH of the leaching solution.

Bench scale catalytic fast pyrolysis of empty fruit bunches over low cost catalysts and HZSM-5 using a fixed bed reactor

The performance of HZSM-5 and low cost catalysts, such as the spent fluid catalytic cracking (FCC) catalyst, bentonite, dolomite, and olivine, on the production of high-quality bio-oil during the catalytic pyrolysis of empty fruit bunches (EFBs) was compared in a bench scale fixed bed reactor. The spent FCC and HZSM-5 catalysts showed higher cracking performance than bentonite, dolomite, and olivine. The catalytic pyrolysis of EFB over the spent FCC catalyst showed higher selectivity to phenol (31.5%) and alkyl phenols (26.0%) due to the effective dealkoxylation of guaiacols and syringols, whereas HZSM-5 provided the higher selectivity to aromatic hydrocarbons (40.4%). The catalytic pyrolysis of EFB over the spent FCC catalyst and HZSM-5 produced bio-oil with a higher heating value (28.44–31.18 MJ/kg) than other bio-oils obtained over bentonite (27.89 MJ/kg) and olivine (16.83 MJ/kg). The bio-oils obtained from the catalytic pyrolysis of EFB over the spent FCC and HZSM-5 catalysts also had a lower viscosity (7.0–13.5 mm2/s) than those (13.8–22.1 mm2/s) over the other catalysts, even after accelerated aging at 80 °C for 1 day.

Catalyst used in fluid catalytic cracking (FCC) unit as a support of NiMoP catalyst for light cycle oil hydroprocessing

The behavior of the NiMoP catalysts prepared by means of impregnation of different supports (MCM-41, SBA-15, catalyst used in FCC unit) has been studied, using them in the hydroprocessing of Light Cycle Oil (LCO) with the aim of maximizing the sulfur removal and reduce polyaromatics content; so the hydroprocessed LCO can be hydrocracked in another unit with metal noble catalysts.Catalysts have been characterized through several techniques: N2 adsorption–desorption, elemental analysis (ICP-AES), X-ray diffraction (XRD), acidity measurement by temperature programmed desorption (TPD) of tert-butylamine, temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), UV–Vis spectroscopy, transmission electron microscopy (TEM), and temperature programmed oxidation (TPO) (spent catalysts). The hydroprocessing runs have been carried out in a fixed bed reactor working in trickle bed regime at 320–400 °C; 80 bar; H2:LCO ratio, 1000mLNH2mL−1LCO; space time, 0.2 h, and time on stream (TOS), 8 h.The catalyst NiMoP/HY-Al2O3 (spent FCC catalyst) stands out due to its high hydrodesulfurization activity attributable to the ease of impregnation of metals over FCC catalyst and the accessibility of the components of the LCO to the hierarchical porous structure. Its activity for reducing polyaromatics compounds of LCO is also remarkable, without diminishing the diesel fraction content by overcracking. Besides, the deposition of coke over this catalyst is scarce, since the retention of the high molecular weight molecules of LCO in its porous structure is minimized.

Recovery of rare earths from spent FCC catalysts by solvent extraction using saponified 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA)

A process to recover rare earth (RE) metals from spent fluid catalytic cracking (FCC) catalysts by solvent extraction was studied, using saponified 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (EHEHPA or P507). The recovery process involved three steps: (1) leaching REs (mainly lanthanum and cerium); (2) solvent extraction by applying saponified P507-kerosene system; (3) stripping. Experiments to assure optimal operating conditions were conducted. Results indicated that RE metals could be recovered effectively from spent catalyst with saponified P507-kerosene-HCl system. At room temperature of 25 °C, 10 g spent catalyst with 110 mL of HCl (1 mol/L) could achieve a leaching efficiency of 85%. For extraction, initial pH value of 3.17, organic/aqueous ratio (O/A ratio) of 2:1 with an extractants’ saponification rate of 20% could obtain 100% efficiency. In the stripping process, 1 mol/L HCl with O/A ratio of 1:1 led to a stripping efficiency of 96%. In the present study, RE metals from spent FCC catalysts were effectively recovered, which avoided wasting a large amount of RE resources. It provides a theoretical support for commercial recycling of RE resources.