Fluid Catalytic Cracking Feedstock Research Articles

Co-processing of organic fraction from groundnut shell biocrude with VGO in FCC unit to produce petrochemical products

This research work explores the transformative potential of biomass leading to sustainable production of biocrude and its utilization in refinery and petrochemical sector for reducing reliance on fossil fuels. In this study, groundnut shell biomass was thermally converted in a customized continuous semi pilot auger reactor in temperature range of 400–700 °C. The optimum temperature for maximizing biocrude was studied, and detailed chemical analysis revealed that biocrude contains hydrocarbons and alcohols with a calorific value of 29 MJ/kg. Furthermore, this study demonstrates the performance of the FCC (Fluid Catalytic Cracking) catalyst and feedstock (H-T- VGO (Hydrothermal vacuum gasoline oil) & Biocrude) in a laboratory-scale utilizing ACE R + MM (Advanced Cracking Evaluation - Residue and Metals Management) unit under predetermined temperatures (515 °C, 525 °C) and a fixed cat-to-oil weight ratio (CTO = 6 w/w). The organic phase and FCC feedstock in different weight ratios from 5 to 20 wt % were blended. There are marginal changes in the yields of dry gas, LCO (light cycle oil) and HCO (heavy cycle oil), with significant increase in the yields of LPG (liquified petroleum gas) and gasoline. Bottoms have been reduced, and coke formation has been adjusted. However, this process requires prudent blending and temperature choices, with future recommendations including improvement in the quality of biocrude to enhance the yields of both LPG and gasoline along with reduced coke formation.

Influence of hydrotreatment depth on product composition of fluid catalytic cracking process for light olefins production

The present work studies the influence of nitrogen compounds in hydrotreated fluid catalytic cracking (FCC) feedstock on the material balance of FCC process focused on petrochemistry. Vacuum gas oil was hydrotreated at the temperatures of 340–370 °C in typical FCC pretreatment conditions. The obtained hydrotreated products contained 370−750 ppm of nitrogen and 150−820 ppm of sulfur. Hydrotreated feedstock was exposed to the FCC process over a zeolite catalyst at the laboratory unit with a fixed bed catalyst at 527 °C and catalyst/oil ratio - 2−6. The FCC feedstock before and after hydrotreatment and FCC products were characterized by different methods to study the effect of nitrogen compounds on the FCC process.

Development of heavy oil upgrading technologies in China

Abstract Heavy oils have high viscosity, density, and Conradson carbon residue and high contents of sulfur, nitrogen, oxygen, nickel, and vanadium, as well as asphaltenes, which can cause problems for producers, leading to catalyst deactivation and fouling and plugging of tubing, pipes, valves, and reactor flow lines. Heavy oil upgrading can be classified into carbon rejection and hydrogen addition processes, mainly including four technologies: (1) the fluid catalytic cracking (FCC) process, which catalytically converts heavy oil into light fractions, like liquid petroleum gas, naphtha, and light cycle oil; (2) the hydro-processing process, which catalytically converts heavy oil to high-quality feedstock for FCC and hydrocracking processes under the hydrogen atmosphere without coke formation; (3) the coking process, which thermally converts heavy oil into light liquid fractions and large amounts of coke; and (4) the solvent deasphalting process, which fractionates distillation resid to provide feedstock for residue FCC, such as the residue oil solvent extraction. This paper reviews the progress on basic research of heavy oil chemistry and processing technology developments in China. Heavy oils were comprehensively characterized by the supercritical fluid extraction and fractionation technology and high-resolution mass spectrometry. The FCC process for maximizing iso-paraffin, new residue hydroprocessing technologies, progress in coking process, and a new process – the Supercritical Fluid Selective Extraction Asphaltene Technology – were discussed. As an emerging and promising research area, molecular management techniques were prospected, as well as a new concept of coupling the SELEX-Asp with the conventional heavy oil upgrading processes.

Fluid catalytic cracking technology: current status and recent discoveries on catalyst contamination

ABSTRACT The fluid catalytic cracking (FCC) technology is one of the pillars of the modern petroleum industry which converts the crude oil fractions into many commodity fuels and platform chemicals, such as gasoline. Although the FCC field is quite mature, the research scope is still enormous due to changing FCC feedstock, gradual shifts in market demands and evolved unit operations. In this review, we have described the current status of FCC technology, such as variation in the present day feedstocks and catalysts, and particularly, great attention is paid to the effects of various contaminants of the FCC catalysts of which the latter part has not been sufficiently documented and analyzed in the literature yet. Deposition of various contaminants on cracking catalyst during FCC process, including metals, sulfur, nitrogen and coke originated from feedstocks or generated during FCC reaction constitutes a source of concern to the petroleum refiners from both economic and technological perspectives. It causes not only undesirable effects on the catalysts themselves, but also reduction in catalytic activity and changes in product distribution of the FCC reactions, translating into economic losses. The metal contaminants (vanadium (V), nickel (Ni), iron (Fe) and sodium (Na)) have the most adverse effects that can seriously influence the catalyst structure and performance. Although nitrogen and sulfur are considered less harmful compared to the metal contaminants, it is shown that pore blockage by the coking effect of sulfur and acid sites neutralization by nitrogen are serious problems too. Most recent studies on the deactivation of FCC catalysts at single particle level have provided an in-depth understanding of the deactivation mechanisms. This work will provide the readers with a comprehensive understanding of the current status, related problems and most recent progress made in the FCC technology, and also will deepen insights into the catalyst deactivation mechanisms caused by contaminants and the possible technical approaches to controlling catalyst deactivation problems.

FCC riser quick separation system: a review

The riser reactor is the key unit in the fluid catalytic cracking (FCC) process. As the FCC feedstocks become heavier, the product mixture of oil, gas and catalysts must be separated immediately at the outlet of the riser to avoid excessive coking. The quick separation system is the core equipment in the FCC unit. China University of Petroleum (Beijing) has developed many kinds of separation system including the fender-stripping cyclone and circulating-stripping cyclone systems, which can increase the separation efficiency and reduce the pressure drop remarkably. For the inner riser system, a vortex quick separation system has been developed. It contains a vortex quick separator and an isolated shell. In order to reduce the separation time, a new type of separator called the short residence time separator system was developed. It can further reduce the separation time to less than 1 s. In this paper, the corresponding design principles, structure and industrial application of these different kinds of separation systems are reviewed. A system that can simultaneously realize quick oil gas separation, quick oil gas extraction and quick pre-stripping of catalysts at the end of the riser is the trend in the future.

Role of nickel on vanadium poisoned FCC catalyst: A study of physiochemical properties

Active sites of Fluid catalytic cracking (FCC) catalyst are poisoned during operation in the FCC reactor due to causes including feedstock contaminant metals deposition. This leads to activity, selectivity and increasing coking problems, thereby raising concern to the refiner. This work investigated effect of nickel coexisting with vanadium in the FCC feedstock on the standard FCC catalyst during cracking process, in which destruction of active sites occurs as a result of the metals deposition. Laboratory simulated equilibrium catalysts (E-cats) were studied by XRD, FTIR spectroscopy, N2 adsorption, solid state MAS-NMR, SEM and H2-TPR. Results revealed that vanadium, above a certain concentration in the catalyst, under hydrothermal conditions, is highly detrimental to the catalyst's structure and activity. Conversely, nickel hardly affects the catalyst structure, but its co-presence in the catalyst reduces destructive effects of vanadium. The mechanism of nickel inhibition of vanadium poisoning of the catalyst is discussed.

Impact of feed properties on gasoline olefin content in the fluid catalytic cracking

ABSTRACTEight vacuum gas oils (VGOs) having different hydrocarbon composition and different distillation characteristics were cracked in a laboratory fluid catalytic cracking (FCC) advanced cracking equipment (ACE) unit. The experimental results showed that FCC VGO feedstock reactivity correlates with the content of saturates plus light aromatics, and with the content of nitrogen. The FCC gasoline olefin content was found to depend on T50% and saturate content of the FCC VGO feedstock. The results from a commercial FCC unit that processes a hydrotreated straight-run VGO and a VGO from ebullated bed residue H-Oil hydrocracker confirmed the results from the laboratory FCC ACE unit showing that reducing T50% and increasing saturate content of the FCC feedstock leads to a reduction of the FCC gasoline content.

Novel Propylene Production Route: Utilizing Hydrotreated Shale Oil as Feedstock via Two-Stage Riser Catalytic Cracking

In this paper, a novel propylene production route is proposed. Hydrotreated shale oil was first used as a feedstock for fluid catalytic cracking (FCC) to increase the propylene yield because of its abundant aliphatic hydrocarbons. The catalytic cracking performance of hydrotreated shale oil was investigated in detail via two-stage riser catalytic cracking (TMP). The results of the pilot-plant-scale TMP indicated that hydrotreated shale oil blended with 30 wt % Daqing vacuum residue could not only maximize the propylene yield but also showed a more desirable product distribution than conventional FCC feedstock. The yield of liquid products (including liquefied petroleum gas, gasoline, and diesel) was as high as 84.93 wt %, and the propylene yield reached 23.62 wt %, whereas the dry gas yield was only 6.06 wt %. This study may provide a novel route to reasonably use shale oil.

Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite

Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) 27Al and 29Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst.

Upgrading of heat carrier oil derived from liquid-phase pyrolysis via fluid catalytic cracking

Second generation biofuel technologies are well investigated to extend the amount of sustainable biofuels. One of the most important criterions for biofuels is their profitability. The bioCRACK process is a new and innovative biomass-to-liquid concept to produce advanced biofuels by liquid-phase pyrolysis. A refinery integrated pilot plant was built up at the OMV refinery in Schwechat (Austria) to provide data for up-scaling. The objective of this publication was to test the suitability of different processed heat carrier oils derived from the bioCRACK process as feedstock for the FCC process. Vacuum gas oil – a typical feedstock for fluid catalytic cracking – was used as heat carrier oil. Different case studies were evaluated, whereas spruce wood and wheat straw were used as feedstock for pyrolysis. All experiments were conducted in a fully continuous small scale pilot plant with internally circulating fluidized bed design. In general, the obtained results show a high conversion efficiency for all performed case studies. Thereby the yield of coke is increased a little. The investigation confirmed that the total fuel yield can be improved even more by additional hydrotreatment. It turned out that the use of a pre-hydrotreated vacuum gas oil for pyrolysis leads to the highest conversion level.

Water-washing to reduce metals in oils extracted from Nannochloropsis algae for potential FCC feedstock

Abstract Algae cultivation offers the potential to produce biofuels with much higher productivity than conventional soil-based crops. Organic oils can be extracted from algae using solvents such as alcohols and paraffins. A challenge is to define the most economical means to process these extracted oils into products such as chemical intermediates and liquid fuels. One approach is to add algal oils directly into the petroleum-based feeds to existing refinery processes such as fluid catalytic cracking (FCC) or hydroprocessing. Maximum acceptable levels were defined for contaminants such as sodium, potassium, calcium, phosphorus, and nitrogen in the feed to an FCC unit, based on refinery experience. Cracking runs in a laboratory unit confirmed the large decrease in conversion for high levels of sodium and potassium. For a laboratory sample of Nannochloropsis algae, the level of metals was far too high in the whole algae or in oils extracted from the algae using ethanol or n-heptane to allow their inclusion in FCC feedstock, even at a level of 2% algal product in the FCC feed. Washing the extracted oil with water removed only modest amounts of metals. It was found that washing the algae with water first, and then doing solvent extractions, resulted in oils with metals levels low enough for co-feeding to an FCC unit at a level of 2%. The oil yields by mass from the starting algae from this route were 21% for ethanol solvent, and 10% for heptane solvent. If an FCC unit were completely dedicated to bio-feeds without the necessity of co-processing petroleum feedstocks, the unit might operate with a different catalyst and different set of operating constraints, but that is beyond the scope of this study.

Catalytic Cracking of C2–C3 Carbonyls with Vacuum Gas Oil

The fluid catalytic cracking (FCC) route could be considered for the co-processing of biomass-derived pyrolysis oil with petroleum-derived vacuum gas oil (VGO) in a typical refinery unit by integrating it with a biomass fast pyrolysis process. This paper aims to study the effect of co-processing pyrolysis oil representative model compounds (C2–C3 carbonyls such as hydroxyacetone and glycolaldehyde dimer) with VGO in a FCC advanced cracking evaluation (ACE-R) unit, using an industrially available FCC equilibrium catalyst (E-CAT). The blending ratios of C2–C3 carbonyls and VGO were varied from 5:95, 10:90, 15:85, and 20:80. The reactor was operated in close to industrial FCC process at a temperature of 530 °C and atmospheric pressure with a catalyst-to-oil ratio of 5.0. The blended FCC feedstock and their liquid distillates were structurally characterized by 1H and gated decoupled 13C NMR techniques. The average structural parameters like branchiness index, substitution index, average length of alkyl chains, and fraction of aromaticity per molecule was obtained from NMR data. A linear increase in FCC conversion was observed with increase in hydroxyacetone blending ratio with VGO from 5% to 20%, which may be due to an increase in propylene and a decrease in heavy cycle oil. Increasing the glycolaldehyde blending ratio from 5% to 10% increased the FCC conversion, while the conversion decreased at ratios of 15% and 20%. The 1H NMR and 13C NMR data indicated that there is an increase in the amount of monoaromatics with increases in the amount of hydroxyacetone, whereas in the case of glycolaldehyde, the monoaromatics increased for blending ratios up to 10% and decreased upon further increases in blending ratio. The equilibrium FCC catalyst is capable of cracking oxygenates presents in pyrolysis oil such as hydroxyacetone and glycolaldehyde toward the production of liquefied petroleum gas (LPG) range products. Furthermore, a scheme has been proposed for the processing of pyrolysis oil in petroleum refinery units.

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.

Upgrading Biodiesel into Oxygen-Free Gasoline: New Applications for the FCC-Process

Using vegetable oils as feedstock for fluid catalytic cracking is a promising and sustainable alternative to oils of fossil origin. Depending on the framework conditions, it may be more reasonable to use fatty acid methyl ester (FAME). For this work, different blends of FAME with vacuum gas oil (VGO) were mixed. At a mean riser temperature of 550°C, pure FAME yielded gasoline (45.7%), crack-gas (18.0%), light cycle oil (LCO) and residue (17.4%) and coke (4.6%). The oxygen contained in the biomass was converted to water (11.9%), CO (2.0%) and CO2 (0.5%). This conversion is one of the key features when using the FCC technology with biomass. The obtained products are therefore free from oxygenates.

Upgrading of Fischer–Tropsch Waxes by Fluid Catalytic Cracking

Synthesis gas originating from alternative feedstocks such as biomass, coal, or natural gas can become an important source of hydrocarbon-based automotive fuels in the future. Fischer–Tropsch synthesis (FTS) affords these hydrocarbons, but upgrading of the primary FTS products is unavoidable. One option is to use the fluid catalytic cracking (FCC) process to convert FTS waxes into a wide range of products. To investigate the impact of FTS wax addition to a conventional FCC feedstock on product yields and properties, microactivity test (MAT) experiments were performed. The tests were performed at 803 K and the catalyst to feed ratio (C/F) was varied in the range 2–4 m/m. The feed contained 0–100% of FTS wax. The addition of FTS wax resulted in increased conversion and yield of the middle distillate fraction (light cycle oil, LCO) and decreased yield of coke. Owing to the increased conversion, higher yields of propylene were obtained by catalytic cracking of feedstocks containing FTS wax. The detailed GC analysis of the products indicated enhanced properties of LCO due to the lowered content of aromatics.

N-Heptane cracking over mixtures of HY and HZSM-5 zeolites: Influence of the presence of phenol

Fluid Catalytic Cracking (FCC) catalysts are based on combinations of two main active phases, the HY and the HZSM-5 (additive) zeolites, but previous studies only concerned the phenol influence on these pure zeolites. Therefore, n-heptane was transformed in presence of phenol over mechanical mixtures of HY and HZSM-5 zeolites, at 450°C, to evaluate the FCC catalysts behaviour during phenolic-rich bio-oils/conventional FCC feedstocks co-processing. Phenol induces an additional deactivation of the zeolites mixtures from the beginning of the reaction because increases the carbon deposition, as for pure zeolites. However, mixing the zeolites, the impact of phenol on HZSM-5 seems to not be as strong as for HZSM-5 alone due to an initial preferential adsorption of phenol on HY, as suggested by the adsorption energies of phenol on these catalysts calculated by Density Functional Theory (DFT), −80kJmol−1 for HY and −60kJmol−1 for HZSM-5. This agrees with the initial products distribution, which points out an enhancement of 14–20% in the paraffins/olefins molar ratio and of about 40% in the amount of branched species on the effluent in presence of phenol, as for pure HY. The HZSM-5 further resistance against phenol, when mixed with HY, decreases by increasing phenol content from 1.2wt.% to 4wt.%. Hence, at an industrial level, the FCC catalyst should suffer a lower effect of phenol on the ZSM-5 additive function than expected, which would be certainly dependent on the amount of each zeolite in the FCC catalysts formulations and on the fraction of phenolic species in the FCC feedstock.

Solventless Deasphalting: Selective Sulfonation Chemistry of Petroleum Asphaltenes and Resids

Asphaltenes are the lowest value component of petroleum. They are found in a variety of crude oils and in higher concentrations in resids and bitumens. Petroleum resid is the non-volatile fraction of crude oil or bitumen after distillation. Current disposition of the asphaltenes is high-temperature thermal chemistry to form higher value liquids and coke or as feedstock for asphalt. Asphaltenes are separated from a resid by a commercial process called solvent deasphalting. Deasphalting is accomplished by treating a resid with a hydrocarbon solvent (propane or butane commercially and pentane−heptane in the lab), and the asphaltenes precipitate out of solution. The rest of the resid is soluble, and this is called the deasphalted oil (DAO). The DAO is recovered by evaporation of the solvent. The DAO is higher value than the original resid, and it is used as residual sulfur fuel oil (RSFO) and, in some cases, as a feedstock for fluid catalytic cracking (FCC) to form higher value liquids. Asphaltenes are compos...

Effect of phenol adsorption on HY zeolite for n-heptane cracking: Comparison with methylcyclohexane

To evaluate the possibility to partially replace the classical Fluid Catalytic Cracking (FCC) feedstocks by bio-oils derived from lignocellulosic biomass, the transformation of n-heptane was performed in the presence of small quantities of phenol over an HY zeolite, at 350 and 450 °C. The results were compared with those previously obtained with methylcyclohexane. Phenol leads to a further deactivation of the zeolite due to phenol adsorption on the Brönsted and Lewis acid sites along with coke molecules from the reactants transformation. For n-heptane, the additional activity decay due to phenol is observed since the beginning of the reaction, while for methylcyclohexane it was only detected after few minutes. The increase of temperature disfavours phenol adsorption but, contrarily to methylcyclohexane, it does not prevent the phenol deactivating effect for n-heptane. Differences in the reactivity of n-heptane and methylcyclohexane molecules and IR spectroscopy data allow concluding that phenol firstly interacts with the stronger protonic sites, being then retained on the weaker acid sites. Alkylation of phenol is a reaction occurring in a lower extent under the conditions tested, being responsible for the consumption of light olefins. Finally, the adsorption of phenol favours the formation of branched molecules. Hence, the alkanes cracking should be more affected than the naphthenes cracking in the co-processing of conventional FCC feedstocks with hydrotreated bio-oils rich in phenolic compounds, being the deactivating effect certainly dependent on the quantity of bio-oils incorporated.

PREDICTION OF PHYSICOCHEMICAL PROPERTIES OF FCC FEEDSTOCK BY CHEMOMETRIC ANALYSIS OF THEIR ULTRAVIOLET SPECTRUM

Chemometric analysis by Partial Least Squares (PLS) has been applied in this work to correlate the ultraviolet spectrum of combined Fluid Catalytic Cracking (FCC) feedstocks with their physicochemical properties. The prediction errors obtained in the validation process using refinery samples demonstrate the accuracy of the predicted properties. This new analytical methodology allows obtaining in one analysis detailed information about the most important physicochemical properties of FCC feedstocks and could be used as a valuable tool for operational analysis.

Production of clean transportation fuels and lower olefins from Fischer-Tropsch Synthesis waxes under fluid catalytic cracking conditions: The potential of highly paraffinic feedstocks for FCC

The potential of Fischer-Tropsch Synthesis (FTS) waxes as a feedstock for fluid catalytic cracking (FCC) has been evaluated with a once-through microriser reactor operating under realistic conditions. The highly paraffinic feedstock has a high reactivity and can be converted under industrial conditions to a high extent (>90wt%). The product distribution can be optimised by the process parameters and catalyst formulation. A high gasoline fraction (70wt%) with a very low aromatics concentration can be obtained. As a result of the formation of i-paraffins, n-olefins and i-olefins the gasoline is expected to possess an acceptable octane number. The reaction scheme derived predicts that the degree of branching in the paraffinic diesel-range product is lower than that of the gasoline-range product and that a relatively good diesel is expected. Due to the absence of sulfur and nitrogen in the feed extremely clean transportation fuels are obtained. The addition of ZSM-5 to an equilibrium catalyst allows the production of significant amounts of light olefins, in particular propene (16wt%) and butenes (15wt%).