Commercial Fluid Catalytic Cracking Catalyst Research Articles

CO2 capture from fluid catalytic crackers via chemical looping combustion: Regeneration of coked catalysts with oxygen carriers

Oil refineries are responsible for ∼5% of total global CO2 emissions and approximately 25–35% of these emissions are released from a single unit called Fluid Catalytic Cracking (FCC). Chemical Looping Combustion (CLC) has been recently proposed as a novel CO2 capture method from the regenerator of FCC units as an integrated process of CLC-FCC. In this study, for the first time, the combustion behaviour of three types of cokes, a model FCC coke (which is a low volatile semi-anthracite coal), and cokes deposited on commercial FCC catalysts by n-hexadecane cracking and Vacuum Gas Oil, were comprehensively investigated with oxygen carriers (Co3O4, CuO, and Mn2O3) in a fixed-bed reactor at 700–850 °C. The results demonstrate that a high coke combustion efficiency was achieved with CuO (98 vol %), Co3O4 (91 vol %), and Mn2O3 (91 vol %) at 800 °C for 30 min. CuO was the most effective oxygen carrier, at temperatures greater than 750 °C for 45 min of residence time. These are the regeneration conditions used in the conventional FCC regenerators.

Quantitative determination of nickel speciation for the presence of free oxide in commercial fluid catalytic cracking catalysts

Motivated by the potential over-catalysis and hazardousness of free nickel oxide (NiO) in the equilibrated catalysts (Ecats) collected from fluid catalytic cracking (FCC) refineries, this study aims to establish a simple bulk method, namely chemical leaching method to rapidly quantify the NiO content within thirteen commercial Ecats collected from different units. The synchrotron-–based, X–ray absorption near–edge structure (XANES) was performed to assess the validity of this method, as well as to examine the coordination structure of Ni by the extended X–ray absorption fine structure (EXAFS) analysis. Additionally, thermodynamics calculation was attempted to validate the affiliation of Ni with other metal oxides. The optimum leaching condition was validated as 60 °C in 60 min using 1 M sulfuric acid. Accordingly, the NiO was determined to reach 70–439 ppm in all Ecats, which warrants a non–hazardousness of these samples. Additionally, for the Ecats with a remarkably higher Ni content, the XANES results are biased by the enrichment of NiO on the catalyst surface. The majority of Ni was found to affiliate with Al in the form of aluminate, with the remaining 11%–15% Ni passivated effectively by lanthanum (La). The oxygen–rich regeneration condition could be beneficial for promoting the affiliation of Ni by La.

Development of Fe-based oxygen carrier using spent FCC catalyst as support for high temperature chemical looping combustion

Chemical looping combustion is based on the transfer of oxygen from air to fuel by means of an oxygen carrier using a metal oxide. This study investigated the development of an oxygen carrier by adding iron to a spent commercial fluid catalytic cracking catalyst (Fe/FCC) and comparing to Fe/Al2O3, and Fe/SiO2 oxygen carriers that may be suitable for the high-temperature (1100 °C) process. The FCC material was chosen as a low-cost oxygen carrier. The FCC support strongly modified the reduction behavior of the Fe-based carrier as compared to the Fe/Al2O3 and Fe/SiO2 carriers. Multicycle studies with CH4 revealed the FCC support impacted the CO2 selectivity (13.5%) at 1100 °C to produce more gaseous CO as compared to the 900 °C (89.7%) due to the formation of FeAl2O4 and Fe2SiO4 phases when the Fe2O3 was reduced at 1100 °C. The FeAl2O4 and Fe2SiO4 phases also considerably slowed the CO2 formation rate on the Fe/FCC oxygen carrier at 1100 °C as compared to the 900 °C reaction tests. The higher-temperature (1100 °C) decreased the oxygen transfer capacity of the Fe/FCC carrier, did not significantly increase the capacity of either the Fe/SiO2 and Fe/Al2O3 carriers. These results suggest that high-temperatures (1100 °C) may lead to carrier transformations through sintering and agglomeration that significantly reduce the kinetics and performance of the oxygen carrier. This research suggests at higher temperatures, shorter reduction times may be necessary to prevent the formation of these phases and the subsequent deactivation of the carrier for total oxidation.

Hydrogen Transfer between Hydrocarbons and Oxygenated Compounds in Coprocessing Bio-Oils in Fluid Catalytic Cracking

Oxygenated model compounds representing typical components of bio-oils and a hydrocarbon hydrogen donor agent were used to study hydrogen transfer reactions between hydrocarbons and oxygenated compounds when coprocessed over acidic commercial fluid catalytic cracking (FCC) catalysts. Phenol, syringol, and trimethoxybenzene were each mixed with tetralin at 5 wt % individually in benzene as an inert solvent. The mixtures were reacted in a fluidized bed, batch CREC Riser Simulator laboratory reactor during 10 s contact time with a catalyst to oil relationship of 3 at 500 °C over a commercial equilibrium FCC catalyst, conditions being selected in order to simulate FCC bio-oil–vacuum gas oil coprocessing. Tetralin was also reacted alone at 5 wt % in benzene to gather background information. When tetralin was the only reactant, its conversion was 87%, the most important reactions being hydrogen transfer, as shown by the yield of naphthalene, and cracking. Alkylation and disproportionation were also observed to a lower extent. In the experiments with the mixtures, the oxygenated compounds converted completely and tetralin converted to less than half the conversion when pure. In these experiments, as compared to pure tetralin, the yield of gases and C11+ hydrocarbons increased and the yield of coke decreased, showing the interaction between the hydrocarbon and the model oxygenated compound reactants. The index SHT, which shows the selectivity to hydrogen transfer reactions from tetralin, increased significantly, to about 2 times, in the experiments with the mixtures. Moreover, coke from pure tetralin was shown to be qualitatively different from that in the experiments with the mixtures, where it was more condensed, thus confirming that the reaction pathways are dissimilar.

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.

Synthesis of Gamma-Alumina from Kankara Kaolin as Potential Zeolite Active Matrix

Commercial fluid catalytic cracking catalysts are manufactured using zeolites dispersed on an amorphous matrix, which is mostly alumina. Alumina is widely used as catalyst support in many heterogeneous catalytic processes owing to its high surface area, superior chemical activity and low cost. In compounded zeolite catalyst it serves as the active matrix which aids the conversion of the bulkiest molecules in the feed owing to its larger pore size than zeolite. Large specific surface area gamma-alumina (γ-Al 2 O 3 ) was synthesized by hydrothermal method using Kankara kaolin as starting material. Thermal treatment of ammonium alum prepared from the filtrate of the dealuminated metakaolin was employed to obtain the alumina. Crystalline aluminum sulfate with 39 wt% Al 2 O 3 was obtained at calcination temperature of 800°C with 3 h soaking. Gamma-alumina was produced at 850°C with 3 h soaking time, having specific surface area of 166 m 2 /g. The weight percent of Al 2 O 3 content in the synthesized and commercial gamma-alumina were 85% and 89% respectively as obtained from the XRF analysis. Good comparison was also observed in the diffractogram of the synthesized and commercial gamma-alumina from the XRD analysis. The Scanning Electron Microscopy (SEM) image showed the platy hexagonal shape of the gamma-alumina. Keywords: Gamma-alumina, zeolite, kaolin

A DNP-supported solid-state NMR study of carbon species in fluid catalytic cracking catalysts.

A combination of solid-state NMR techniques supported by EPR and SEM-EDX experiments was used to localize different carbon species (coke) in commercial fluid catalytic cracking catalysts. Aliphatic coke species formed during the catalytic process and aromatic coke species deposited directly from the feedstock respond differently to dynamic nuclear polarization signal enhancement in integral and crushed FCC particles, indicating that aromatic species are mostly concentrated on the outside of the catalyst particles, whereas aliphatic species are also located on the inside of the FCC particles. The comparison of solid-state NMR data with and without the DNP radical at low and ambient temperature suggests the proximity between aromatic carbon deposits and metals (mostly iron) on the catalyst surface. These findings potentially indicate that coke and iron deposit together, or that iron has a role in the formation of aromatic coke.

Particle size effect on the catalyst attrition in a lab‐scale fluidized bed

Catalysts readily suffer from particle attrition in fluidized beds. In this article, a commercial fluid catalytic cracking catalyst was sieved into several particle‐size intervals to investigate the size effect on particle attrition. It is shown that an exponential decay equation presents a suitable description of attrition and that catalyst attrition is dependent on particle size. Steady‐state specific attrition rate decreases with increasing particle size; however, initial specific attrition rate and decay time parameter change irregularly. For comparison of attrition resistances, a long attrition test is required to reach steady‐state attrition, and the steady‐state specific attrition rate is recommended. It is seen that the smallest particle‐size interval is the most seriously attrited, while the two largest particle‐size intervals are the most attrition‐resistant. Furthermore, weak interactions appear among attrition behaviors of different intervals, and a linear combination method is effective to combine all interval samples to predict the attrition of the original full‐sized sample. © 2016 American Institute of Chemical Engineers AIChE J, 63: 914–920, 2017

Comparative study of attrition measurements of commercial FCC catalysts by ASTM fluidized bed and jet cup test methods

Catalyst loss due to fines generation by attrition is a major problem in refinery fluid catalytic cracking (FCC) units as it impacts inventory loss. Attrition resistance of catalyst is one of the critical parameter in catalyst selection for a FCC unit. ASTM D5757 fluidized bed attrition test is the most commonly used attrition resistance test method to rank FCC catalysts and additives. In the present study, catalyst attrition tests were performed for FCC catalysts using an ASTM fluidized bed, cylindrical jet cup and conical jet cup. Performance ranking shows that attrition index obtained by these tests vary, but the order of ranking remains unchanged for ASTM fluidized bed and conical jet cup test methods as compared to cylindrical jet cup test. The investigation conducted here shows that morphology of attrited fresh FCC catalyst using conical jet cup was found to be similar to plant equilibrium catalyst and also takes less attrition time relative to ASTM fluidized bed.

Synergy in the Cracking of a Blend of Bio-oil and Vacuum Gasoil under Fluid Catalytic Cracking Conditions

The catalytic cracking of a blend of raw bio-oil (20 wt %) from black poplar sawdust fast pyrolysis and vacuum gasoil (VGO, 80 wt %) has been studied. The runs have been performed in a riser simulator reactor (RSR) under fluid catalytic cracking (FCC) conditions; that is, 500–560 °C, catalyst to feed mass ratio of 6 gcat (gfeed)–1 on a dry basis, reaction times of 3–10 s and a equilibrated commercial FCC catalyst. The cofeeding effect has been quantified by comparing the yields of product lumps and individual components in the gaseous fraction and gasoline lump in the cracking of VGO, raw bio-oil, and their blend (20% bio-oil/80% VGO), at the same conversion values (60–70 wt %). The cofeeding has a favorable synergy because it promotes the formation of C3–C4 and gasoline (C5–C12) hydrocarbon lumps, attenuating the formation of CO2, CO, and also coke formation. In the cracking of the blend (80% VGO/20% bio-oil) at 70 wt % conversion, a deoxygenation degree of 95 wt % has been obtained, with a total liquid ...

The Influence of Temperature and Catalyst Additives on Catalytic Cracking of a Heavy Fuel Oil

The effects of reaction temperature and catalyst additives on the fluid catalytic cracking (FCC) products yield have been studied through cracking of a heavy fuel oil obtained from Tehran refinery. The catalytic performance was assessed using a commercial equilibrium USY FCC catalyst (E-Cat) in a fixed-bed micro-activity test unit. Two types of ZSM-5 zeolites with different SiO2/Al2O3 ratios together with MCM-41 were tested as additives. Different reaction temperatures of 550, 600 and 640°C were investigated for the corresponded E-Cat/Additives. MAT results showed that more propylene and the highest propylene to ethylene ratio can be obtained via E-Cat/MCM-41 at 550°C. Applying ZSM-5 zeolite led to enhancement in total olefins production. Different behaviors were observed using two ZSM-5 additives. Butenes production followed a similar fashion through all additives at the three temperatures tested.

Production of aromatic compounds in the heavy naphtha and light cycle oil ranges: catalytic cracking of aromatics and C10 naphthenic‐aromatics

AbstractBACKGROUNDThe conversions of bicyclic compounds, both a naphthenic‐aromatic compound (tetralin) and an aromatic compound (naphthalene), as model reactants representative of the heavy gasoline and light cycle oil (LCO) cuts in fluid catalytic cracking (FCC), were studied to understand the formation of C10–C20 aromatic compounds in gasoline and middle distillates cuts, in view of their impact on the properties of the cuts. A commercial FCC catalyst was used in its fresh, hydrothermally de‐aluminated and equilibrium forms, at 450 °C in a fluidized bed CREC Riser Simulator reactor in the 2–8 s reaction time range.RESULTSProducts were C1–C14 hydrocarbons and coke. Based on the product distributions, reaction networks were proposed for both reactants. The reactions considered in the networks were hydrogen transfer, cracking, ring opening and contraction, alkylation and disproportionation.CONCLUSIONThe load of zeolite in the catalysts and their acidities have the strongest influences on reaction selectivities. In the case of tetralin, the prevalent reaction is hydrogen transfer, which becomes more important as the catalysts are less active, the hydrocarbons with highest yields being C10 aromatics. Cracking reactions predominate in naphthalene conversion over all the catalysts, a fact which favors mono‐aromatic C9− hydrocarbons. These results can help in the design of new FCC catalysts with better selectivity control. © 2014 Society of Chemical Industry

Characteristics and Kinetics of Coked Catalyst Regeneration via Steam Gasification in a Micro Fluidized Bed

Petroleum residue cracking combined coke gasification (RCCG) process was proposed to regenerate the catalyst via coke-steam gasification for syngas production, thus to solve the problem of excessive heat generated via coke combustion in the industrial fluid catalytic cracking (FCC) process. A commercial FCC catalyst and a bifunctional (BF) catalyst were used as the candidates for the RCCG process, and the BF catalyst was specially designed with both catalytic effects of oil cracking and coke gasification. The regeneration characteristics and kinetics of FCC and BF catalysts were studied using a micro fluidized bed. The results showed that high-quality syngas was produced when regenerating the catalysts via steam gasification and the sum of H2 and CO in the produced gas was over 80 vol % under electrically heated condition.The gasification rate first increased with increasing carbon conversion and then slowly decreased. In comparison with FCC catalyst, the regeneration time of BF catalyst was shortened by more than 30% via addition of alkaline metal oxides and adjustment of its pore size. Homogenous model (HM) and shrinking core model (SCM) were used to calculate the regeneration kinetic parameters of coked catalysts. It was found that the activation energies from these two models were close to each other, while HM had a better fitting relevance for the data than SCM. The activation energy of BF catalyst regeneration was about 115 kJ·mol–1, lower than that of FCC catalyst (150 kJ·mol–1), demonstrating that BF catalyst was easier to regenerate via coke gasification and also justified its bifunctional characteristics. The activation energy of coke gasification on BF catalyst could be further decreased to 45 kJ·mol–1 when introducing 3% oxygen as the gasification reagent.

Fluid catalytic cracking: Processing opportunities for Fischer–Tropsch waxes and vegetable oils to produce transportation fuels and light olefins

Fluid catalytic cracking (FCC) of Fischer–Tropsch (FT) waxes and vegetable oils could be an attractive option to produce transportation fuels and light olefins. For FT waxes, the catalytic cracking using commercial FCC catalysts revealed that a particular product slate (gasoline, diesel or light olefins) with high selectivity can be obtained by selecting an appropriate catalyst and operating conditions. FT wax is an outstanding feedstock in providing a high-value petrochemical feedstock, propene, with yields about 25wt.% by employing pure ZSM-5 or ZSM-5/FCC catalyst (Y-zeolite-based) mixture. Similar amounts of butenes are also obtained. For the catalytic cracking of vegetable oils, the product distribution primarily depends on the degree of unsaturation (double bonds) of vegetable oils. For gasoline with high selectivity, saturated vegetable oils are more preferable. Irrespective of the degree of unsaturation, the aromatic content of the product fractions is relatively high compared to those from the conventional FCC feedstocks (VGO). Further modification of a FCC catalyst with a suitable metal (nickel) along with co-feeding H2 tremendously increases the gasoline and light olefins yields from a vegetable oil. Thus, development of a novel catalyst and/or tuning catalyst characteristics is still a promising research area to focus onto improve the cracking performance of vegetable oils. The cracking data of FT waxes/vegetable oils with VGO showed that co-processing of renewable feedstocks with the conventional FCC feedstocks is promising and no significant interactions exist between conventional and renewable feedstocks. Consequently, the prediction of the cracking performance at different blend ratios is straightforward.

Copyrolysis of scrap tires with oily wastes

In this study, the conversion of hazardous wastes into liquid fuels was investigated. The pyrolysis of bilge water oil and oil sludge from ships, scrap tires and their blends was carried out at 400 and 500°C in absence and presence of catalyst. A commercial fluid catalytic cracking catalyst and Red Mud were used as catalyst. Pyrolysis products were separated as gas, oil and char. The pyrolytic oils were characterized by using gas chromatography-mass selective detector (GC-MSD) and 1H nuclear magnetic resonance (1H-NMR). The effect of temperature and catalyst on the product distribution and the composition of oil from pyrolysis were investigated. Co-pyrolysis of scrap tire with oily wastes from ships produced oil that could be used as fuel, while its pyrolysis alone produced oil that could be used as a chemical feedstock. The results obtained in this study showed that co-pyrolysis of oily wastes with scrap tires could be an environmentally friendly way for the transformation of hazardous wastes into valuable products such as chemicals or fuels.

Enhancing propylene production from catalytic cracking of Arabian Light VGO over novel zeolites as FCC catalyst additives

The catalytic cracking of vacuum gas oil over fluid catalytic cracking (FCC) catalyst containing novel additives was investigated to enhance propylene yield. A conventional ZSM-5, mesoporous ZSM-5 (Meso-Z), TNU-9 and SSZ-33 zeolite were tested as additives to a commercial equilibrium USY FCC catalyst (E-Cat). Their catalytic performance was assessed in a fixed-bed micro-activity test unit (MAT) at 520 °C and various catalyst/oil ratios. The cracking activity of all E-Cat/additives did not decrease by using these additives. The highest propylene yield of 12.2 wt.% was achieved over E-Cat/Meso-Z compared with 9.0 wt.% each over E-Cat/ZSM-5 and E-Cat/TNU-9, at similar gasoline yield penalty. The enhanced production of propylene over Meso-Z is attributed to its mesopores that suppressed secondary and hydrogen transfer reactions and offered easier transport and accessibility to active sites. The lower enhancement of propylene over the large-pore SSZ-33 additive was due to its high-hydrogen transfer activity. Gasoline quality was improved by the use of all additives, as octane rating increased by 7–12 numbers for all E-Cat/additives.

Performance Comparison of Spray-Dried Oxygen Carriers: The Effect of NiO and Pseudoboehmite Content in Raw Materials

The effect of NiO and pseudoboehmite content in raw materials on the performances of spray-dried oxygen carriers was investigated. Oxygen carriers were prepared by the spray-drying method using 60, 70, and 80 wt % NiO and γ-Al2O3. For 70 wt % NiO, γ-Al2O3 mixed with 0, 5, and 10 wt % pseudoboehmite was used as raw support materials. The prepared oxygen carriers showed excellent physical properties suitable for fluidized-bed process applications. Oxygen carriers prepared using 70 wt % NiO showed higher attrition resistance than that of other oxygen carriers and a commercial fluid catalytic cracking catalyst. Especially, the calcination temperature to obtain sufficient mechanical strength was lowered to 1000 °C for the oxygen carrier prepared using 70 wt % NiO and 30 wt % γ-Al2O3. The oxygen carriers prepared using 70 and 80 wt % NiO and calcined at 1100 °C showed high oxygen transfer capacities and oxygen utilization above 13.3 wt % and 88.7%, respectively. However, the oxygen utilization of the oxygen car...

Catalytic and Thermal Pyrolysis of Atmospheric Residue

Pyrolysis of Chinese Daqing atmospheric residue on the commercial catalytic pyrolysis process (CPP) catalyst, commercial fluid catalytic cracking (FCC) catalyst, and quartz sand was investigated using a confined fluidized bed reactor system. The pyrolysis behaviors of the commercial CPP catalyst were similar to those of the commercial FCC catalyst, while they were different from those of quartz sand. The reaction extent of the thermal pyrolysis on quartz sand was high, and the yield of total light olefins was 36.88 wt % at 660 °C and 41.88 wt % at 700 °C. The commercial CPP catalyst showed the best pyrolysis performance and obtained the highest yield of total light olefins. The use of catalysts accelerates not only the cracking reaction, but also the hydrogen transfer and isomerization reactions. Both the free radical mechanism and the carbonium ion mechanism play an important role for the catalytic pyrolysis of Daqing atmospheric residue for light olefin production.

Utilizing Colloidal Silica and Aluminum-Doped Colloidal Silica as a Binder in FCC Catalysts: Effects on Porosity, Acidity, and Microactivity

This paper reports on the synthesis and characterization of fluid catalytic cracking (FCC) catalysts using two different colloidal silica materials as binders, where one was doped with 2 wt % Al2O3 and the other was without any dopant. The physicochemical properties such as attrition resistance, particle size distribution, surface areas, porosity, morphology, chemical environment, and acidity were investigated employing various analytical and spectroscopic techniques such as N2 sorption, scanning electron microscopy, transmission electron microscopy, 29Si and 27Al MAS NMR, and temperature programmed desorption of ammonia (NH3-TPD). It was observed that the FCC catalysts synthesized using colloidal silica have larger particle sizes than that synthesized using sodium silicate (baseline catalyst) as a binder and lower than that of a commercial FCC catalyst. They also exhibit relatively lower attrition resistance than the commercial and the baseline FCC catalysts; however, they exhibit higher BET and matrix s...

Waste catalysts for waste polymer

Catalytic cracking of high-density polyethylene (HDPE) over fluid catalytic cracking (FCC) catalysts (1:6 ratio) was carried out using a laboratory fluidized bed reactor operating at 450 °C. Two fresh and two steam deactivated commercial FCC catalysts with different levels of rare earth oxide (REO) were compared as well as two used FCC catalysts (E-Cats) with different levels of metal poisoning. Also, inert microspheres (MS3) were used as a fluidizing agent to compare with thermal cracking process at BP pilot plant at Grangemouth, Scotland, which used sand as its fluidizing agent. The results of HDPE degradation in terms of yield of volatile hydrocarbon product are fresh FCC catalysts ≫ steamed FCC catalysts ≈ used FCC catalysts. The thermal cracking process using MS3 showed that at 450 °C, the product distribution gave 46 wt% wax, 14% hydrocarbon gases, 8% gasoline, 0.1% coke and 32% nonvolatile product. In general, the product yields from HDPE cracking showed that the level of metal contamination (nickel and vanadium) did not affect the product stream generated from polymer cracking. This study gives promising results as an alternative technique for the cracking and recycling of polymer waste.