Spent FCC Catalyst Research Articles

Catalytic Cracking of Hdpe Pyrolysis Volatiles over a Spent Fcc Catalyst

The effect of temperature in the catalytic cracking of HDPE over a spent FCC catalyst on the product distribution has been studied using a two-step reaction system. Thermal pyrolysis of HDPE has been carried out in a conical spouted bed reactor and the volatiles formed (mainly waxes) have been fed in-line into a catalytic fixed bed reactor. An increase in the second stage temperature from 450 °C to 550 °C gives way to an enhancement of cracking reactions, achieving full conversion of waxes at 550 °C. At this temperature, gasoline and light olefins are the main product fractions obtained, with a yield of 52 wt% and 28 wt%, respectively.

Use of high-resolution thermogravimetric analysis (HRTG) technique in spent FCC catalyst/Portland cement pastes

Thermogravimetric analysis is one of the most common instrumental techniques used for the characterization of pastes, mortars and concretes based on both calcium hydroxide and Portland cement. Important information about pozzolanic materials can be assessed concerning calcium hydroxide consumption and the formation of new hydrated products. Nevertheless, in some cases, problems associated with the overlapped decomposition processes for hydrates make the analysis of obtained data difficult. In this paper, the use of high-resolution thermogravimetric analysis, a powerful technique that allows separating decomposition processes in analysis of hydrated binders, was performed for spent FCC catalyst—Portland cement pastes. These pastes were monitored for 1, 4, 8 h and 1, 2, 3, 7 and 28 curing days. In order to study the influence of the pozzolanic material (spent FCC catalyst), Portland cement replacements of 5, 15 and 30 % by mass were carried out. The presence of spent FCC catalyst in blended pastes modified the amount and the nature of the formed hydrates, mainly ettringite and stratlingite.

Gas leakage between reactors in a dual fluidized bed system

The leakage of gas between two interconnected gas–solid fluidized beds is investigated for 48 operating conditions in a lab-scale dual fluidized bed (DFB) consisting of a riser and a bubbling fluidized bed (BFB). Helium is used as the tracer gas with a spent FCC catalyst bed in ambient conditions. Gas leakage occurs from the riser to the BFB via the downcomer; and from the BFB to the riser via the loop-seal. Gas leakage from the riser to the BFB varied between 0.1 and 0.6%, translating to 1 and 7% of the BFB being contaminated with riser gas. This leakage is dependent on pressure difference across the downcomer and the solids circulation flux. Leakage in the downcomer is proposed to be caused by the riser gas being dragged down by the falling particles in the upper section of the downcomer.

Spent FCC Catalyst for Preparing Alkali-Activated Binders: An Opportunity for a High-Degree Valorization

Spent FCC catalyst is a waste from the petrochemical industry which has excellent pozzolanic properties, containing more than 90% silica and alumina. Its similarity to metakaolin creates interesting prospects for its use in the production of alkali-activated binders. In this study, the alkali activation of this residue, spent FCC catalyst, through mixtures with alkali hydroxide and silicate solutions (both sodium and potassium) has been carried out. The alkali cation had an important role in the nature of AA-FCC pastes: some differences in the mass loss in the thermogravimetric tests and in the X-ray mineral characterization were found. No significant differences in compressive strength were observed for mortars cured for 3 days in several conditions: room temperature and 65oC. Prepared AA-FCC mortars had a compressive strength of about 65-70 MPa. Microstructural studies showed that an amorphous, dense and compact microstructure was obtained, independent of the activating solution and curing condition.

Investigation on corrosion control of mild steel buried in soil by spent FCC catalyst coating

Effects of aerobic and anaerobic bacteria on corrosion behaviour of mild steel coated with modified spent FCC catalyst have been examined in soil extract solutions (SES) and that buried in soil. Coating of modified spent FCC catalyst was found to inhibit the growth of bacterial isolates from the soil which is represented as zone of inhibition. Efficacy of spent FCC catalyst was studied for the coated coupons immersed in SES. Cracks and interstices were found on uncoated coupons due to corrosion whereas coated surface remained unaffected. This is confirmed by the SEM analysis. It was also seen that coated coupon was undamaged under buried-in-soil conditions for 30 days.

Spent FCC catalyst: Potential anti-corrosive and anti-biofouling material

To combat corrosion and biofouling in chemical and marine industries with green and cheap material many efforts are put. Efficacy of spent FCC catalyst coating was studied for these purposes. Its corrosion resistance against corrosive media was examined up to 80°C and 6h by two methods. They indicated high corrosion inhibition efficiency. Antibacterial and antibiofouling activity of zeolite was studied for bacteria isolated from seawater. Zeolite coating was subjected to cooling water to observe antifouling behaviour and the performance was found to improve upon some modifications. The metal deposited on zeolite did not leach away in stagnant and flowing waters.

Chromium removal by zeolite-rich materials obtained from an exhausted FCC catalyst: Influence of chromium incorporation on the sorbent structure

A spent FCC catalyst was converted into a zeolitic mixture, and the product obtained was afterward used as trapping material for Cr(III) species frequently found in aqueous solutions. Eventual changes in the sorbent structure produced by Cr incorporation were studied by different characterization techniques such as point of zero charge determinations (PZC), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and infrared absorption (FTIR). The XRD and FTIR analyses indicated that chromium incorporation produces an amorphization of the material, and PZC measurements show no surface adsorption of charged chromium species. SEM and EDX analyses clearly show that after chromium sorption, the initial microspheroidal catalyst morphology was maintained, and the presence of chromium species was mainly detected in the outer microsphere surface, where the zeolite crystals were hydrothermally grown.

Catalytic fast pyrolysis of straw biomass in an internally interconnected fluidized bed to produce aromatics and olefins: Effect of different catalysts

A novel reactor, named internally interconnected fluidized bed (IIFB), was specially designed for catalytic fast pyrolysis (CFP) of straw biomass. Catalytic characteristics of four types of catalysts (ZSM-5, LOSA-1, Gamma-Al2O3 and spent FCC catalysts) for producing aromatics and olefins were investigated in this reactor. The results show that IIFB reactor can realize CFP process. The maximum carbon yields of aromatics (12.8%) and C2-C4 olefins (10.5%) were obtained with ZSM-5. ZSM-5 shows the highest selectivity of naphthalene (12.1%), whereas spent FCC catalyst presents the highest selectivity of benzene (45.5%). The selectivity of ethylene and propylene are equal in the present of ZSM-5 and LOSA-1. Gamma-Al2O3 and spent FCC catalysts show a higher selectivity of ethylene than that of propylene. This paper provides a new reactor for CFP process and some suggestions for choosing catalyst.

Early Hydration of Calcium Aluminate Cement Blended with Spent FCC Catalyst at Two Temperatures

The early hydration (up to 24h) of calcium aluminate cement (Al2O3 min. 40%) blended with spent FCC catalyst at two temperatures i.e. 10 ̊C and 25 ̊C was investigated. The calorimetric measurements were used to study cement pastes with constant ratio of water/binder = 0.5 (binder = cement + addition) and containing 0, 5 and 25% mass of mineral waste as replacement part of cement. In addition the kind of created products using X-ray diffraction method was identified.On the basis of obtained results it was found that the influence of spent FCC catalyst on early hydration of calcium aluminate cement strictly depends on temperature of hydration process. At the temperature of 25 ̊C this waste aluminosilicate accelerates setting and hardening of cement, but at the temperature of 10 ̊C acts as retarder. These changes are realized by variation of duration of the induction period and the bigger content of FBCC the bigger the effect is regardless of the temperature of hydration. The presence of this mineral waste causes a minor effect on the crystalline hydrates produced after 1 day of hardening although it clearly increases degree of CA hydration.

Polyethylene Cracking on a Spent FCC Catalyst in a Conical Spouted Bed

The catalytic cracking of HDPE (high density polyethylene) at 500 °C using a spent FCC catalyst agglomerated with bentonite (50 wt %) has been studied in a conical spouted bed reactor. The reaction is carried out in continuous regime (1 g min–1 of HDPE is fed) with no bed defluidization problems. The results obtained, namely, total conversion, and high yields of gasoline (C5–C11 fraction) (50 wt %) and C2–C4 olefins (28 wt %), are explained by favorable reactor conditions and good catalyst properties. These results are compared with those for a catalyst prepared in the laboratory by agglomerating a commercial HY zeolite (SiO2/Al2O3 = 5.2). The conical spouted bed is a suitable reactor for enhancing the physical steps of melting the polymer and coating the catalyst with the melted polymer. Furthermore, high heat and mass transfer rates promote devolatilization, and short residence times minimize secondary reactions from olefins by enhancing primary cracking products. The meso- and macroporous structure of the spent FCC catalyst matrix enhances the diffusion of long polymer chains, whereas the zeolite crystals have micropores that give a proper shape selectivity to form the lumps of gasoline and light olefins. Because of long use in reaction–regeneration cycles, the moderate acidity of the spent FCC catalyst minimizes the secondary reactions of hydrogen transfer, and so restricts the formation of aromatics and paraffins, as well as the reactions of overcracking and condensation and, therefore, the coke formation. The spent FCC catalyst exhibits a low deactivation rate and is regenerable by coke combustion with air at 550 °C. Consequently, the use of a catalyst with the sole cost of a simple agglomeration and the production of value added product streams make the process of polyolefin catalytic cracking a promising option for refinery integration.

Reuse of Spent FCC Catalyst for Removing Trace Olefins from Aromatics

adsorption-desorption and inductively coupled plasma optical emission spectrometer (ICP-OES)were used to investigate the pretreatment process. The result showed that the performance of the treated spentFCC catalyst was much greater than that of the spent FCC catalyst, which indicted the possibility andimprovement of this research.Key Words : Spent FCC catalyst, Ultrasonic reactor, Olefins, ModificationIntroductionThis paper described some potentially interesting resultson the re-use of spent FCC catalyst for the removal ofolefins from an essentially feed and the theme is of interestbecause the application or re-use of spent FCC catalyst is soimportant for environment concerns.The amount of spent FCC catalyst discarded as solid wastehas increased significantly in recent years due to the greatdemand for lightly and high quality transportation fuels aswell as the changes in feedstock. Most of these spentcatalysts have been disposed off as landfill in approveddump-sites.

Investigation of early hydration of high aluminate cement-based binder at different ambient temperatures

Abstract The effect of spent FCC catalyst on early hydration (up to 48 h) of high aluminate cement (Al2O3 >70%) at different ambient temperatures (10, 20, and 30 °C) was investigated. Cement pastes with constant ratio of water/binder = 0.35 (binder = cement + addition) and containing 0, 5, 10, and 15% mass of addition as replacement of cement were studied. The hydration kinetics was determined by calorimetric measurements and the structure of hardened binders after 2 days of curing at an appropriate temperature was also investigated using X-ray, SEM, and thermal analysis methods. Due to the fact that hydration of aluminate cements is highly sensitive to temperature conditions as well as certain changes of temperature are inevitable in practice, the evaluation of the impact of the waste catalyst addition in such conditions is justified. On the basis of obtained results, it was stated that the temperature determines the early hydration of high aluminate cement and decides about the influence of waste alumin...

Studies on the influence of spent FCC catalyst on hydration of calcium aluminate cements at ambient temperature

The influence of spent catalyst from catalytic cracking in fluidized bed (FCC) on the hydration of two kinds of calcium aluminate cements (of about 40 and 70% content of alumina) was studied. Cement pastes were prepared with constant ratio of water/binder = 0.5 and with content of 0, 5 and 25% mass of addition as replacement of cement. The samples were stored at room temperature. Thermal analysis (TG, DTG), infrared absorption (FTIR) and X-ray diffraction methods were applied to investigate changes in various periods of hydration (up to 150 days). The compressive strength of cement mortars was also examined. On the basis of presented results it was affirmed that in studied conditions spent FCC catalyst is a reactive addition in calcium aluminate cement (CAC) pastes, which probably can create a new phase type C–A–S–H. It may be an interesting alternative for limitation of the negative phenomenon of conversion of aluminate hydrates, although the degree of the influence of the mineral additive depends on the composition of CAC and of the quantity of the used waste.

Composition of aromatic products in the catalytic degradation of the mixture of waste polystyrene and high-density polyethylene using spent FCC catalyst

In this chemical recycling process, spent FCC catalyst used had an advantage with an economical and environment aspect, such as a low catalyst price in liquid-phase reaction and a reuse of waste catalyst. The characteristics of oil product and its aromatic product distribution, as a function of reaction time in the reactor and also proportion of HDPE and PS in the mixture, were compared. Main products obtained were light hydrocarbons within the gasoline range that were mainly produced during initial reaction time. The formation of aromatic products such as styrene and ethylbenzene as major components depended appreciably on the reaction time, as well as the composition of HDPE and PS in the mixture used for degradation. For the distribution of C 9–C 12 alkylaromatic components as by-products, methylstyrene (C 1-styrene) and isopropylbenzene (C 3-benzene) components were the main products formed by β-scission and hydrogen transfer of PS, while the rest of alkylaromatic products showed very low fraction being 1% or less.

Chemical catalysed recycling of polypropylene over a spent FCC catalyst and various commercial cracking catalysts using TGA

Thermogravimetric analysis (TGA) has been used as a tool to characterise the activity, regenerability and deactivation behaviour of spent FCC commercial catalyst (FCC-s1) in the degradation of polypropylene. The FCC-s1 catalysts and amorphous silica–alumina (SAHA) significantly reduced the activation energy as compared with thermal process, and zeolites (ZSM-5 and HUSY) further reduced the activation energy. However, silicalite catalysts gave very minimal effect on PP degradation at a temperature similar to that of thermal cracking. Analysis of the TGA results allowed a relationship between catalyst activity and coke content to be derived. The activity of FCC-s1 catalysts was found to fall exponentially with coke content, and it could be recover most its initial value. The results represent an interesting alternative to have significant impact on the economics of a catalytic polymer degradation process employing post-use FCC commercial catalysts of zero market value.

Segregation and mixing effects in the riser of a circulating fluidized bed

Segregation and mixing effects of binary mixtures of particles having difference in sizes and densities were studied in 0.1016 m-diameter riser of a circulating fluidized bed at gas velocities between 2.01 and 4.681 m/s and solids circulation rate between 12.5 and 50 kg/m 2 s. Two groups of bed materials (three quartz sand–spent fcc catalyst mixtures with different initial mass % of sand and two coal–iron mixtures, one with almost same sizes but with different densities and the other having both different sizes and densities) were used. Using local axial mass % of heavier/coarser particles and their mean sizes the extent of segregation was evaluated. The influence of operating conditions like superficial gas velocity and solids circulation rate on segregation was examined and found that with their increase segregation effects generally tend to decrease and a uniform mixture conforming to initial composition of the mixture results. Using the data available in the literature and those of the present authors an empirical correlation to obtain the extent of segregation in CFBs has been proposed.

Chemical catalysed recycling of waste polymers: Catalytic conversion of polypropylene into fuels and chemicals over spent FCC catalyst in a fluidised-bed reactor

Polypropylene (PP) was pyrolysed over spent FCC commercial catalyst (FCC-s1) using a laboratory fluidised-bed reactor operating isothermally at ambient pressure. The influence of reaction conditions including catalyst, temperature, and ratio of polymer to catalyst feed and flow rates of fluidising gas was examined. The yield of gaseous and liquid hydrocarbon products at 390 °C for spent FCC commercial catalyst (87.8 wt%) gave much higher yield than silicate (only 17.1 wt%). Greater product selectivity was observed with FCC-s1 as a post-use catalyst with about 61 wt% olefins products in the C 3–C 7 range. The selectivity could be further influenced by changes in reaction conditions. Valuable hydrocarbons of olefins and iso-olefins were produced by low temperatures and short contact times used in this study. It is also demonstrated that a post-use catalyst system under appropriate conditions the resource potential of polymer waste can be economically recovered and also can address the recycling desire to see an alternative to solve a major environment problem.

Degradação de poliolefinas utilizando catalisadores zeolíticos

Neste trabalho foi estudada a degradação de alguns dos principais constituintes dos rejeitos plásticos (polietileno de alta densidade (HDPE), polietileno de baixa densidade (LDPE) e polipropileno (PP)), empregando-se um catalisador exausto de unidades de craqueamento de fluidos (FCC) e um catalisador zeolítico (ADZ3) sintetizado em laboratório. Utilizando técnicas de termogravimetria (TG-DTG) e cromatografia gasosa (CG), foi possível avaliar os produtos gerados no craqueamento destas poliolefinas. Na degradação catalítica de poliolefinas com catalisadores zeolíticos, verificou-se a obtenção preferencial de gasolina, GLP e diesel, produtos importantes na matriz energética brasileira. O catalisador de FCC exausto foi mais seletivo para a produção de gasolina e GLP, enquanto que a produção de diesel foi mais favorecida com o catalisador ADZ3.

Liquid-phase catalytic degradation of mixtures of waste high-density polyethylene and polystyrene over spent FCC catalyst. Effect of mixing proportions of reactants

The catalytic degradation of waste high-density polyethylene (HDPE) and polystyrene (PS) mixtures with a different mixing proportions over spent FCC catalyst has been studied using a stirred semi-batch reactor at 400 °C. The cumulative amount distribution, the degradation rate into liquid products, the carbon number distribution, and the paraffin, olefin, naphthene and aromatic (PONA) distribution in the liquid product were determined as a function of time or mixing proportion of reactants. The cumulative amount distribution of liquid product depended on the mixing proportion of both HDPE and PS. The degradation rate in the range of initial lapsed time (initial degradation rate) increased exponentially with PS content whereas that for the range of final lapsed time (final degradation rate) increased slowly with HDPE content. An increase of PS content in the reactants showed an increase of gasoline fraction, from about 85 wt.% (0 wt.% PS content) to about 98 wt.% (100 wt.% PS content). Liquid PONA product distributions revealed the interaction of the degraded intermediates from HDPE and PS degradation. The addition of PS to the catalytic degradation of HDPE accelerated the production of aromatic components with mono-cyclic species in liquid products and moreover showed the highest selectivity of above 60 wt.% for ethylbenzene and styrene (C 2 benzene) in aromatic products

Ag-Based Catalytic Additives for the Simultaneous Reduction of NO and CO Emissions from the Regenerator of a FCC Unit

Spent FCC catalyst was regenerated in a fluidized-bed reactor at 700 °C using a 2% O2 in N2 feed. The NO and CO emissions during regeneration were measured when Ag-based additives were used and compared with those when a commercial Pt-based CO promoter (1% CP-3) was added. All Ag/alumina additives exhibited high NO reduction ability (up to 70%), with the highest deNOx efficiency achieved with moderate Ag loading (3%). A different trend was measured for the CO emissions: the higher the Ag loading (1−5%) on alumina, the higher was the CO oxidation. However, higher CO emissions were always measured when Ag-based additives were used as compared to those when CP-3 was used. The Ag-based additives exhibited stability problems, as disaggregation of Ag particles from the alumina support was observed. When the support was promoted with 10% Ce, stable Ag-based additives were synthesized and the CO oxidation ability was enhanced. When we increased the metal loading (up to 10% Ag) and/or the Ce percentage (up to 20%) on the catalytic support, the CO oxidation over Ag/Ce-based additives was further enhanced and the NO reduction was maintained to adequately high levels (≥36%). The NO and CO emissions were simultaneously reduced to the desired level, when we increased the amount of the most promising additive (Ag(5%)/Ce(20%)CPBase) in the reactor or when we used this additive in combination with small amounts of CP-3. The performance of Ag/Ce-based additives was linked with formation of different crystal phases on the additive. The presence of the Ag2O crystal phase on the most promising additive resulted in the reduction of the NO and CO emissions. When the Ag loading increased, metallic silver was formed that enhanced the CO oxidation.