Cracking Catalyst Research Articles

Recycling of a spent residue-fluid-catalytic cracking catalyst into an adsorbent for the removal of copper(II) ions from wastewater

The recycling of spent residue fluid catalytic cracking (RFCC) catalysts into adsorbents addresses both waste management and environmental pollution. Herein, we aimed to extract metals from spent RFCC catalysts, subject them to hydrothermal treatment and washing processes, and characterized by XRD, FT-IR, XPS, BET and SEM techniques, which also evaluating their efficiency as adsorbents. The spent RFCC catalyst was washed for 3 h and hydrothermally treated at 100 °C for 24 h, resulting in RFCC-A with a surface area of 81.77 m²/g and an average diameter of 66.81 nm, the cation-exchange capacities of up to 4300 – 5325 meq/100 g. The washing process removed 40 % – 46 % of vanadium and 12 % – 13 % of nickel. The derived adsorbent demonstrated a Cu(II) ion removal capacity of 120 mg/g from wastewater within 1 h at pH 4, and a total adsorption capacity of 831.68 mg/g after three regenerations. The primary removal mechanism was cation exchange involving electrostatic attraction. The manufacturing cost of the adsorbent was 59.5 USD/kg, equating to 0.50 USD/g Cu(II), with regeneration costs under 1 USD/g Cu(II). These findings indicate that using spent RFCC catalyst-derived adsorbents is cost effective and environmentally beneficial.

Rational screening of metal single-atom-doped ZSM-5 to promote ring-opening cracking of cycloalkanes to light olefins

The ring-opening cracking of cycloalkanes to light olefins poses a formidable challenge due to the sluggish activation of the C–C bond. In this study, we realize the rational screening of various single metal doped M−ZSM−5 catalysts (M = Mn, Co, Ni, Cu, Zn, Zr, Ru, Rh, Pd, Ag, Pt) to promote the ring-opening cracking of cycloalkanes to light olefins. Our calculation results show that methyl cyclopentane, a model compound of cycloalkanes, tends to adsorb in the form of a “half-chair” configuration in the intersecting channels of the M−ZSM−5, which is caused by the drastic distortion of the five-membered ring, accompanied by large changes in the bond angles. Based on the host–guest interaction between the active site and hydrocarbon in ring-opening cleavage, we reveal that the binding energies of metals to H and C can respectively quantify the metal’s ability to activate C–H and C–C bonds in cycloalkanes. By solving the microkinetic model, we plot activity-selectivity TOF volcano diagrams, where Mn, Ru, Rh-ZSM-5 within the EH range of −2.5 to −3.5 eV and the EC range of −6 to −8 eV can efficiently induce the ring-opening reaction of cycloalkanes without excessive dehydrogenation leading to aromatic hydrocarbon formation. The calculation shows good agreement with catalytic experimental tests and in situ DRIFT spectra results, providing a series of potential candidate catalysts for the ring-opening cracking of cycloalkane-rich diesel fuel.

Promoting fine particle removal in cyclone by spray agglomeration and heterogeneous condensation

By adding a spray chamber in front of the cyclone separator, spray agglomeration and heterogeneous vapor condensation were combined to improve the removal effect of the cyclone separator on fine particles, which is used for the deep treatment of high-humidity industrial flue gas and fine particles. Fine particles can form agglomerates through the capture effect of micron droplets, and can also grow in size through heterogeneous vapor condensation in supersaturated water vapor environment, thus being effectively removed by cyclone separators. Supersaturated water vapor environment was a necessary condition for heterogeneous vapor condensation. Numerical simulation results showed that supersaturated water vapor environment can be formed in the spray chamber when the relative humidity of the original flue gas was high, and the higher the relative humidity, the higher the supersaturation and the larger the supersaturation area. The experimental results indicated that spray agglomeration and spray coupling heterogeneous condensation increased the particle removal efficiency of the cyclone separator by 11.6 % and 22.6 %, and the removal efficiency in the 2–4 μm “fish-hook” range was increased by 21.6 % and 41.7 %, respectively. This technology was successfully applied for the first time in the deep treatment of the tail gas in Fluid Catalytic Cracking (FCC) catalyst production industry, which can ensure that the particle emission concentration was within 20 mg/Nm3.

The impact of spent fluid catalytic cracking catalyst on the selected mechanical and physical performances of cement mortars

This paper presents the results of research aimed for evaluating the impact of applicability of spent fluid catalytic cracking catalyst as a substitute of 20, 40, 60 and 80% of cement, by mass, in cement mortars on their selected mechanical and physical performances. It was demonstrated that substitution of 20% of cement mass with spent catalyst enhanced mortar’s compressive strength for 16.7%. Further addition of spent catalyst tended to decrease strength, whilst, simultaneously, rose the values of capillary absorption and water absorptivity because of deterioration of cement matrix structure, documented by SEM photos. Based on the research and literature data, it was proved that spent cracking catalyst might be a promising additive to cement in the amount not exceeding 40% of its mass considering its pozzolanicity

Zeolite-modified alumina-bead catalyst for hierarchical cracking of bulky molecules

A novel zeolite-modified alumina-bead catalyst (ZSM-5/Al2O3-b) was prepared via calcining zeolite-coated alumina-bead material (Al2O3-b@ZSM-5) to graft zeolitic acid sites on the alumina-bead surface. The acid catalyst proved high activity and more 8 times catalytic efficiency than the corresponding ZSM-5(5 %) + Al2O3 mechanically mixed catalyst for cracking of 1, 3, 5-triisopropylbenzene (TIPB) in the FCC simulation reactor with short contact time. The characterization results showed that the surface property of the alumina-beads has been modified and the interface connection of Si-O-Al bonds between zeolitic nanoparticles and alumina resulted in stable zeolite particles on the alumina surface and the structural stability in hot water. The excellent catalytic performances are ascribed to the decrease of diffusion limitation of reactants and intermediates and the increase of Brønsted acid sites on the ZSM-5/Al2O3-b catalyst. The grafted/modified alumina-bead catalyst can be directly used in practical catalytic cracking of large molecules without forming. This strategy can be extended to the preparation of other types of zeolite-containing catalysts and industrial applications.

BASF introduces Fourtiva fluidized catalytic cracking catalyst to increase high octane gasoline blending feedstock

BASF introduces Fourtiva fluidized catalytic cracking catalyst to increase high octane gasoline blending feedstock

Exploring the influence of different precursor materials on the catalytic performance and deactivation characteristics of iron-loaded biochar catalysts for the catalytic cracking of toluene

This study employed rice husks (RH), corn stalks (CS), and camphor leaves (CL) as biomass sources to prepare iron-loaded biochar catalysts, elucidating the key relationships between these biomass materials, their catalytic performance, and their resistance to deactivation in toluene. Experimental results indicated that the carbon deposits in the three spent catalysts are primarily composed of inert carbon (Cγ). The carbon peaks in these deposits primarily consisted of CO, CC, and CO structures, with varying proportions across the different types of spent catalysts. Specifically, the RH spent catalyst exhibited the highest relative content of the CO structure at 13.49 %, the CS spent catalyst showed the highest relative content of the CC structure at 89.19 %, and the CL spent catalyst displayed the highest relative content of the CO structure at 5.57 %. Fe2+ was the predominant species on the surfaces of all three spent catalysts, accounting for over 50 % in each case. Fe3C was detected on the surfaces of the CS and CL spent catalysts but was absent on the RH spent catalyst. After 80 min of reaction, the carbon deposition rate of the CL catalyst was 8.15 %, with a catalytic cracking efficiency of 28.04 %, making it the most effective overall. This effectiveness was attributed to the CL catalyst's highest oxygen vacancy intensity, where the abundant oxygen source effectively promoted the catalytic reaction of toluene and inhibited carbon deposition. After three consecutive regeneration cycles, the catalytic cracking efficiency of the CL catalyst remained above 70 %, demonstrating strong cyclic regeneration performance. This study provides theoretical insights into the effective utilization of agricultural and forestry waste, contributing to environmental protection.

Selective conversion of spent cracking catalyst to faujasite-structured zeolites

Current recycling strategies for spent catalyst in Fluid Catalytic Cracking (FCC) focus on valuable rare-earth elements (REE) and sometimes include a reuse of spent materials by down-cycling, which hinders a circular economy. Herein, a new procedure for the selective conversion of spent FCC catalysts to FAU-type zeolite without secondary crystalline phases such as sodalite, zeolite P or zeolite A is reported. The steps include a leaching process of REE, followed by thermal activation with sodium hydroxide and acid treatment to get an aluminum-rich feed. The synthesis of FAU-type zeolites with varying Si/Al ratios uses the aluminum-rich catalyst feed and commercial water glass. The experiments show that incorporation of silicate from water glass into the zeolite structure is limited to zeolite products with Si/Al ratio ≤ 2.0. It indicates a flocculation of silicates in higher concentration in competition to the crystallization process of FAU-type zeolites. This is reinforced by the resulting crystals, covered and surrounded with small particles with morphology of silica. Moreover, a clear differentiation between zeolite Y and zeolite X is possible from materials properties with the definite evidence of a mixed phase. The kinetics of feed dissolution and incorporation of impurities, alumina and silica are controlled by the pre-treatment temperature, duration and silicon source. This enables flexible adjustment of the aluminum re-use from spent FCC catalyst, the amount of foreign elements (Fe, Ni, V), phase purity, Si/Al ratio, specific surface area and thermal stability of the final zeolite product. Structural and textural data of the resulting zeolites reveals high crystallinity > 80 %, Si/Al ratios of 1.6–2.0, and specific surface areas up to 780 m2/g.

Zn-doped bentonite catalysts for waste engine oil cracking: Thermal treatment offers a cleaner alternative to acid activation

This study investigates the cracking of waste engine oil (WEO) using bentonite clay (BC) activated through acid and thermal methods, as well as with Zn-doped BCs. Acid activation with 1 M HCl and Zn doping did not alter the BC catalyst’s structure. XRD and SAED analyses confirmed the crystallinity, while TEM showed partial destruction of the layered structure. XRF analysis indicated reduced Al and Si content upon Zn-doping due to high cation exchange capacity. Zn-doping decreased surface area and pore volume but increased acidic sites in acid-treated catalysts, although Zn suppressed these sites in calcined BC. Zn-doped catalysts displayed higher thermal stability. Cracking WEO at 450 °C for 45 min, with and without catalysts, yielded high liquid product recovery (72.6 %–82.8 %), primarily carboxylic acids and aromatics. This demonstrates the potential of Zn-doped BC as an effective catalyst for converting WEO into valuable products, aiding waste management and resource utilization.

Unveiling the potential of desert sand-derived mesoporous silica supported nickel-based catalysts for co-production of H2 and carbon nanomaterials via methane cracking

This study investigates the replacement of a costly commercial silicate source with locally abundant desert sand in the United Arab Emirates (UAE), for synthesizing mesoporous silica. Hydrothermal synthesis methods were employed to develop various mesoporous materials having different pore geometries, namely MCM41-S, SBA15-S and MCF-S, using desert sand as a silica source. These materials were then impregnated with 15 wt% NiO (∼13 wt% Ni) by sono-wet impregnation technique. All Ni-based silica supported catalyst demonstrated enhanced stability at 550 °C during the reaction. It was observed that the synthesized MCF-S proves to be a highly efficient catalyst support, as Ni/MCF-S, for the catalytic decomposition of methane (CDM), exhibiting the highest methane conversion (60 %), which is 1.4–2.1 times higher than the Ni-based classic-structured mesoporous siliceous supported catalysts, such as SBA15-S and MCM41-S. In particular, the H2 yield (62 %) of the Ni/MCF-S catalyst was 1.40 and 2.38 times higher than that of the Ni/SBA15-S and Ni/MCM41-S catalysts, respectively. To understand the observed differences, a detailed characterization of the physicochemical properties of these materials was conducted. The results revealed that the macro/mesopores size (4–60 nm) and bimodal sinusoidal pore geometry of MCF-S, played a critical role in enhancing Ni particle dispersion, resulting in the highest active Ni metal surface area (7.66 m2/gcat) and contributing to the improved catalytic activity of Ni catalysts in methane cracking.

Co-pyrolysis of refinery oil sludge with biomass and spent fluid catalytic cracking catalyst for resource recovery.

Catalytic co-pyrolysis of two different refinery oily sludge (ROS) samples was conducted to facilitate resource recovery. Non-catalytic pyrolysis in temperatures ranging from 500 to 600°C was performed to determine high oil yields. Higher temperatures enhanced the oil yields up to ~ 24 wt%, while char formation remained unchanged (~ 45%) for S1. Conversely, S2 exhibited a notably lower oil yield (~ 4 wt%) than S1. Pyrolysis oil of S1 consisted of phenolics (~ 50% at 600°C) whereas hydrocarbons were predominant in S2 oil (~ 80% at 600°C). Catalytic pyrolysis of S1 did not exhibit a substantial impact on oil yields but the oil composition varied significantly. High hydrocarbons, phenolics, and aromatics were obtained with molecular sieve (MS), metal slag, and ZSM-5, respectively. Catalytic co-pyrolysis of S2 with sawdust (SD) in the presence of MS enhanced the oil yield, and the resulting oil consisted of high hydrocarbons (~ 54%) and aromatics (~ 44%).

Designing highly active hydrotalcite-derived NiAl catalysts for methane cracking to H2

Designing nickel-based methane cracking catalysts with excellent catalytic activity and surveying their transition during the catalytic process with varied reaction condition have been challenge. In this paper, NiAl catalysts were prepared by reduced hydrotalcite precursor for efficient catalytic methane cracking to produce hydrogen. The catalysts were characterized by XRD, N2 physisorption, XPS, SEM, TEM, Raman and TGA. The effects of preparation method, Ni/Al ratio and reaction temperature on methane cracking performance were revealed and the transformation for the Ni particles during the reaction process was analyzed. The results indicated that the catalyst performance of hydrotalcite-derived NiAl catalysts is superior to Ni/Al2O3 catalysts prepared by the conventional impregnation method, which maybe due to the better Ni dispersion and uniform average particle size distribution with around 12.7 nm compared with the agglomeration of the Ni/Al2O3 particles for up to 53.2 nm. The catalyst with a Ni/Al molar ratio of 3 exhibited the optimal catalytic activity with a stability for 75 min at nearly 90 % hydrogen yield at 700 °C. The reaction temperature also suggested a positive correlation between the hydrogen yield and the reaction temperature from 600 °C to 800 °C. Moreover, based on the investigation of the catalysts during the reaction transition state, Ni particles sintered rapidly from 10.2 nm to 31.2 nm at the beginning reaction time with the high hydrogen yield and then tended to be stable, which may be correlated well with the degree of graphitization of the deposited carbon. This paper provides a valuable design for efficient methane cracking catalysts.

PP upcycling employing FCC spent catalyst: The role of contaminants, atmosphere and pressure

Innovative and sustainable approaches are being pursued to convert plastic waste into high-value fuels, particularly without using noble metal catalysts or external hydrogen sources. In this scenario, we explored the utilization of a spent fluid catalytic cracking (FCC) catalyst (ECAT), aiming to enhance the yield and quality of products through catalytic cracking of Polypropylene (PP) under different reaction conditions. Under a 20 bar H2 atmosphere, ECAT efficiently cracked PP into alkanes (71.6 %) and aromatics (25.5 %), with minimal alkenes (2.2 %) production. Similarly, under a 20 bar N2 atmosphere, ECAT achieved comparable conversion levels, producing mainly saturated hydrocarbons, which was intriguing. However, tests conducted at 1 bar N2 pressure showed that PP conversion remains unaffected but presents higher olefins’ yield and lower aromatics than ECAT. Thus, pressure seems to favor aromatization and in situ hydrogen transfer. By comparing the performance of ECAT with commercial CBV 712 zeolite, we propose that PP acts as an internal hydrogen source, eliminating the need for external supply improving efficiency and selectivity. Interestingly, mechanistic insights suggested that dehydroaromatization and hydrogen transfer within zeolite pores were dominant, and pressure (H2 or N2) could have helped it. In addition, contrary to previous studies that claim that metal contaminants in ECAT are essential for the hydrogenation process, our findings suggest that for this particular ECAT composition, we do not observe any boost in alkane yield due to the presence of these metals. Hence, our study comprehensively evaluates different strategies that can be employed to promote PP upcycling promoted by ECAT.

Machine learning aided design of single-atom alloy catalysts for methane cracking

The process of CH4 cracking into H2 and carbon has gained wide attention for hydrogen production. However, traditional catalysis methods suffer rapid deactivation due to severe carbon deposition. In this study, we discover that effective CH4 cracking can be achieved at 450 °C over a Re/Ni single-atom alloy via ball milling. To explore single-atom alloy catalysis, we construct a library of 10,950 transition metal single-atom alloy surfaces and screen candidates based on C–H dissociation energy barriers predicted by a machine learning model. Experimental validation identifies Ir/Ni and Re/Ni as top performers. Notably, the non-noble metal Re/Ni achieves a hydrogen yield of 10.7 gH2 gcat–1 h–1 with 99.9% selectivity and 7.75% CH4 conversion at 450 °C, 1 atm. Here, we show the mechanical energy boosts CH4 conversion clearly and sustained CH4 cracking over 240 h is achieved, significantly surpassing other approaches in the literature.

An Industrial Perspective for Sustainable Polypropylene Plastic Waste Management via Catalytic Pyrolysis—A Technical Report

Recycling plastics on an industrial scale is a key approach to the circular economy. This study presents a techno-economic analysis aimed at recycling polypropylene waste, one of the main consumer plastics. Specifically, it evaluates the technical and economic feasibility of achieving a large-scale cracking process that converts polypropylene waste into an alternative fuel. Pyrolysis is considered as a promising technique to convert plastic waste into liquid oil and other value-added products, with a dual benefit of recovering resources and providing a zero-waste solution. This study concerns a fast catalytic pyrolysis in a fluidized bed reactor, with the presence of a fluid catalytic cracking catalyst of low acidity for high heat transmission, for an industrial plant with a capacity of 1 t/h of polypropylene waste provided by the Greek Petroleum Industry. From the international literature, the operational conditions were chosen pyrolysis temperature at 430 °C, pressure at 1atm, heating rate at 5 °C/min, and yields of products to 71, 14, and 15 wt.%, for liquid fuel, gas, solid product, respectively. The plant design includes a series of apparatuses, with the main one to be the pyrolyzer. The catalytic method is selected over the non-catalytic because the presence of catalyst increases the quantity and quality of the liquid product, which is the main product of the plant. The energy loops of recycling pyrolysis gas and char as a low-carbon fuel in the plant were considered. The production cost, annual revenue, for 2023, are anticipated to reach €13.7 million (115 €/t) and €15 million (15 €/t), respectively, with an estimated investment equal to €5.3 million. The Payback Time is estimated to 2.4 years to recover the cost of investment. The endeavor is rather economically sustainable. A critical parameter for large scale systems is securing feedstock with low or negligible price.

Synthesis of customized zeolite X with outstanding CO2 selectivity over CH4 and N2 using facile activated spent fluid catalytic cracking catalysts

Efficient separation of CO2 from natural gas mixtures (CO2/CH4) and flue gas (CO2/N2) is pivotal for effective carbon capture and sequestration. Utilizing adsorbents derived from solid waste provides additional benefit for the carbon capture industry. This study introduces a convenient activation method at 200 °C for SFCC. Utilizing the activated SFCC as raw material under mild hydrothermal conditions, highly crystalline zeolite X (referred to as SFCC-X-200) of commercial quality with exceptional CO2 separation ability from CH4 and N2 is obtained. The static water adsorption rate of SFCC-X-200 meets the requirements of the national standard for commercial zeolite X (GB6287-86). Moreover, the ideal adsorbed solution theory (IAST) selectivity of SFCC-X-200 for CO2 from CO2/N2 (15/85, v/v) and CO2/CH4 (50/50, v/v) mixtures is significantly higher, at 797 and 199, respectively, compared to commercial X zeolite. SFCC-X-200 demonstrates tremendous potential for separating CO2/N2 and CO2/CH4 mixtures due to its outstanding adsorption capacity and selectivity, rapid attainment of adsorption equilibrium, complete desorption at ambient temperature, and extremely low cost.

The possibility of partial substitution of cement in cement mortars with the use of spent fluid catalytic cracking catalyst from polish oil refinery: mechanical performances and impact of the addition of superplasticizer

This paper presents the results of a study of the effect of spent catalytic cracking catalyst derived from polish oil refinery used as a partial replacement of cement (in the amount of 20, 40, 60 and 80% of cement mass) in the binder on the mechanical strength of cement mortars, prepared without and with superplasticizer. It was shown that the replacement of 20% of cement, by mass, with spent catalyst increased the compressive strength of mortars without and with superplasticizer dosage by 16.7% and 24.4%, respectively, and did not deteriorate the flexural strength of samples prepared with superplasticizer. With the increasing amount of spent catalyst (above 40% by weight of cement), a decrease in the strength of mortars was observed. This indicates that spent catalyst from catalytic cracking might be a promising material as a binder replacement in cementitious composites when used in smaller amounts (less than 40%).

Hierarchical Y Zeolite-Based Catalysts for VGO Cracking: Impact of Carbonaceous Species on Catalyst Acidity and Specific Surface Area.

The performance of catalysts prepared from hierarchical Y zeolites has been studied during the conversion of vacuum gas oil (VGO) into higher-value products. Two different catalysts have been studied: CatY.0.00 was obtained from the standard zeolite (Y-0.00-M: without alkaline treatment) and CatY.0.20 was prepared from the desilicated zeolite (Y-0-20-M: treated with 0.20 M NaOH). The cracking tests were carried out in a microactivity test (MAT) unit with a fixed-bed reactor at 550 °C in the 20-50 s reaction time range, with a catalyst mass of 3 g and a mass flow rate of VGO of 2.0 g/min. The products obtained were grouped according to their boiling point range in dry gas (DG), liquefied petroleum gas (LPG), naphtha, and coke. The results showed a greater conversion and selectivity to gasoline with the CatY.0.20 catalyst, along with improved quality (RON) of the C5-C12 cut. Conversely, the CatY.0.00 catalyst (obtained from the Y-0.00-M zeolite) showed greater selectivity to gases (DG and LPG), attributable to the electronic confinement effect within the microporous channels of the zeolite. The nature of coke has been studied using different analysis techniques and the impact on the catalysts by comparing the properties of the fresh and deactivated catalysts. The coke deposited on the catalyst surfaces was responsible for the loss of activity; however, the CatY.0.20 catalyst showed greater resistance to deactivation by coke, despite showing the highest selectivity. Given that the reaction occurs in the acid sites of the zeolite and not in the matrix, the increased degree of mesoporosity of the zeolite in the CatY.0.20 catalyst facilitated the outward diffusion of products from the zeolitic channels to the matrix, thereby preserving greater activity.

Cu MOF-biocarbon functional catalysts as adsorbent for oxygen-linked carbon capture via thermo-catalytic pyrolysis: A low-carbon fuel synthesis strategy

Low-carbon fuel synthesis is encouraged as it is environmentally benign and aims to lessen the impact of global warming. This experimental investigation examines the synthesized Bombax ceiba oil (Bio-oil) based pyrolyzed oil utilizing Cu MOF-biocarbon catalysts (0.15 wt.%) via thermo-catalytic cracking and adsorption. The structural and thermal characteristics of the developed Cu MOF - biocarbon catalysts are investigated using Field Emission – Scanning Electron Microscopy/Energy Dispersive Spectroscopy (FE-SEM/EDAX), Attenuated Total Reflectance-Infrared Spectroscopy (ATR-IR), X-Ray Diffraction (XRD), Thermogravimetry-Differential Thermal Analysis (TG-DTA) and Brunauer-Emmett-Teller (BET). Following a thermo-catalytic reaction with a hot plate magnetic stirrer (600 rpm, 100 °C, and 1 h), the oily Cu MOF-biocarbon catalysts are separated from the pyrolyzed green fuel using high-speed centrifugation. The cracking and adsorption of the pyrolyzed green oil compounds are studied using 1H NMR, GC–MS, and thermal conductivity. The results indicate that alkane compounds increase from 3.25 to 6.70 % whereas oxygen incorporated compounds decrease from 96.75 to 93.30 % in the pyrolyzed oil. Furthermore, the GC–MS study shows that the separated oily catalysts adsorb 44.52 % of hydrocarbon (CH) and oxygen-linked (CHO) hydro-carbon compounds. Overall, the newly synthesized Cu MOF-biocarbon is considered as a potential functional catalyst for cracking and adsorption of alkane/oxygen bonded compounds (e.g., CH, CO etc.,), promoting the pyrolyzed oil as low-carbon fuel for better sustainable environment.

Complex-Oxide Catalysts in Cracking of Propane

Complex-Oxide Catalysts in Cracking of Propane