Fluid Catalytic Cracking Catalyst Research Articles

Performance, combustion, and emission characteristics of bio-oil produced by in situ catalytic pyrolysis of polypropylene using spent FCC.

Plastic waste is a rich source of hydrocarbons that can be converted into bio-oil through pyrolysis. In this study, bio-oil was produced by pyrolysis of waste-polypropylene using spent FCC catalyst. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that catalytically produced oil has the majority of compounds in the hydrocarbon range of C6-C18. The catalytic pyrolysis oil was blended with conventional fuel (diesel) to extensively investigate its suitability as a fuel substitute in a single-cylinder, four-stroke, 3.5kW, diesel internal combustion (IC) engine. Furthermore, four fuels, i.e., CF100PO00 (pure diesel), CF90PO10 (10% v/v pyrolysis oil blended with diesel), CF85PO15 (15% v/v pyrolysis oil blended with diesel), and CF80PO20 (20% v/v pyrolysis oil blended with diesel), were tested in IC diesel engine for performance, combustion, and exhaust emission analysis at 1500rpm. The tests were carried out at five loads, i.e., 1, 5, 10, 15, and 20 Nm. It was found that CF90PO10 produced 6.61% higher brake thermal efficiency (BTE), whereas CO2 exhaust emission decreased by 20% for CF80PO20 with respect to the pure diesel. Diesel blends with plastic pyrolysis oil can be a promising biofuel to improve engine performance and combustion characteristics without any significant engine modification.

Improving catalytic performance of Cu-SSZ-13 for NOx abatement via in-situ introduction of La and Ce from spent catalyst

Designing a cost-effective and fast fabrication Cu-SSZ-13 with improved selective catalytic reduction of NO by ammonia (NH3-SCR) performance remains an open question. Here we report that LaCe-SSZ-13 zeolites were synthesized from spent fluid catalytic cracking catalyst within 12 h. After ion-exchanging with CuSO4 solution, the obtained LaCeCu-SSZ-13 catalysts exhibit significantly higher catalytic activity and hydrothermal stability than conventional Cu-SSZ-13. Various characterizations reveal that La and Ce modification not only facilitates the disperse of isolated Cu2+ species, but also effectively mitigates dealumination and inhibits copper species aggregation after hydrothermal aging. In-situ diffuse reflection infrared Fourier transform spectrum analyses demonstrate that La and Ce modification can accelerate the adsorption capacity for NH3 and NOx and promote the decomposition of NH4NO3 intermediate species on the catalyst, benefiting the improvement of low-temperature activity. The combination of experiments and theoretical calculations further demonstrate that the most stable positions of La and Ce are on different eight-membered rings in SSZ-13, and then Cu2+ ions tend to enter eight-membered rings to enhance the NH3 adsorption capacity and decrease the H2O adsorption capacity, which results in higher low-temperature activity and hydrothermal stability than Cu-SSZ-13. Our work provides a feasible strategy for preparing the efficient rare-earth-modified Cu-zeolite based NH3-SCR catalyst for nitrogen oxide abatement.

Catalytic Copyrolysis of Used Waste Plastic and Lubricating Oil Using Cu-Modification of a Spent Fluid Catalytic Cracking Catalyst for Diesel-like Fuel Production.

This work provided catalytic copyrolysis of spent lubricating oil (SLO) with waste low-density polyethylene (LDPE) using copper modification of a spent fluid catalytic cracking (sFCC) catalyst to produce diesel-like fuels in a microbatch reactor, which will lead to effective waste management, ensure sustainability, and serve as an alternative energy source. The effects of LDPE blended with SLO, temperature, reaction time, and catalyst loading using an inert nitrogen atmosphere were investigated on the yields and distributions of copyrolyzed oil, while metal modification of the sFCC was prepared and used to investigate the catalytic activity. The temperature and time of reaction played an important role in the gaseous contribution to the pyrolysis of SLO. The addition of the LDPE ratio in the catalytic copyrolysis, including Cu loading on a spent FCC template, also enhanced the acidity and was responsible for the catalytic activity, which could improve the product distribution and chemical compounds in a range of diesel-like fuels. It was shown that the pyrolyzed oil was in the range of C7-C26 with a maximum diesel-like fraction of 23.11 ± 2.88 wt % compared with the catalytic pyrolysis of SLO alone, which contained a diesel-like fraction of only 12.45 ± 1.92 wt %. It was noticed that the acid active site of the catalyst resulted in a carbon-carbon bond cleavage and further secondary reaction, leading to the conversion of the long residue fraction into a light oil product. In addition, the LDPE ratio in the catalytic copyrolysis could improve the product distribution and chemical compounds in a range of diesel-like compounds, as confirmed by the GC/MS analysis. Catalytic copyrolysis oil of the optimal process condition (0.7:0.3 mass molar of SLO/LDPE, 450 °C, 60 min, 3 wt % Cu-sFCC, and 10 wt % catalyst loading) mainly contains light hydrocarbons in the C7-C19 range. Accordingly, both the product selectivity and the conversion of the long residue to the diesel-like fraction were nearly stable (59.01 ± 1.36%) during the catalyst reusability test from one to three cycles without regeneration and significantly decreased after the fifth cycle. This is an indication that the copyrolysis enhanced the conversion of SLO by LPDE blended into smaller hydrocarbon compounds, and the catalytic activity therefore showed a major tendency toward the formation of diesel-like fractions (C8-C18).

Micro-flow structure at regime transition from bubbling to turbulent fluidization in a fluidized bed

Gas-solid fluidized beds have found extensive utilization in frontline manufacturing, in particular as low-velocity beds. The fluidization status, the bubbling or turbulent flow regime and the transition in between, determine the system performance in practical applications. Though the convoluted hydrodynamics are quantitively evaluated through numerous data-processing methodologies, none of them alone can reflect all the critical information to identify the transition from the bubbling to the turbulent regime. Accordingly, this study was to exploit a coupling data processing methodology, in the combination of standard deviation, power spectrum density, probability density function, wavelet transform, and wavelet multiresolution method, to jointly explain the micro-flow structure at the regime transition from bubbling to turbulent fluidization. The transient differential pressure fluctuation was measured for the evaluation in a fluidized bed (0.267 m i.d. × 2.5 m height) with FCC catalysts (d¯p=65μm, ρp=1780kg/m3) at different superficial gas velocities (0.02–1.4 m/s). The results show that the onset of turbulent fluidization starts earlier in the top section of the bed than in the bottom section. The wavelet decomposition displays that the fluctuation of differential pressure mainly concentrates on the sub-signals with an intermediate frequency band. These sub-signals could be synthesized into three types of scales (micro-scale, meso-scale, and macro-scale), representing the multi-scale hydrodynamics in the fluidized bed. The micro-scale signal has the characteristic information of bubbling fluidization, and the characteristic information of turbulent fluidization is mainly represented by the meso-scale signal. This work provides a systematic comprehension of fluidization status assessment and serves as an impetus for more coupling analysis in this sector.

Home Trash Biomass Valorization by Catalytic Pyrolysis

With the increase in population, large amounts of food waste are produced worldwide every day. These leftovers can be used as a source of lignocellulosic waste, oils, and polysaccharides for renewable fuels. In a fixed bed reactor, low-temperature catalytic pyrolysis was investigated using biomass gathered from domestic garbage. Thermogravimetry, under N2 flow, was used to assess the pyrolysis behavior of tea and coffee grounds, white potato, sweet potato, banana peels, walnut, almonds, and hazelnut shells. A mixture of biomass was also evaluated by thermogravimetry. Waste inorganic materials (marble, limestone, dolomite, bauxite, and spent Fluid Catalytic Cracking (FCC) catalyst) were used as catalysts (16.7% wt.) in the pyrolysis studies at 400 °C in a fixed bed reactor. Yields of bio-oil in the 22–36% wt. range were attained. All of the catalysts promoted gasification and a decrease in the bio-oil carboxylic acids content. The marble dust catalyst increased the bio-oil volatility. The results show that it is possible to valorize lignocellulosic household waste by pyrolysis using inorganic waste materials as catalysts.

Thermodynamic modelling of cements clinkering process as a tool for optimising the proportioning of raw meals containing alternative materials

The valorisation of waste or by-products in Portland clinker production is a promising alternative for developing sustainable cements. The complexity of the chemical reactions during clinkering demands an adequate dosing method that considers the effect of feedstock impurities to maximise the potential substitution of natural resources by waste or by-products, while guaranteeing the clinker reactivity requirements. This study proposes a raw meal proportioning methodology for optimising co-processing of natural feedstocks with alternative raw materials in clinker production, intending to reduce the content of natural raw materials needed, while promoting an optimal clinker reactivity. A thermodynamic modelling sequence was developed considering the variability of raw materials composition and heating temperatures. The model was then validated by comparing simulation outcomes with results reported in previous studies. An experimental case study was conducted for validation of the proposed method using a spent fluid catalytic cracking catalyst (SFCC), a by-product from the oil industry as an alternative alumina source during clinkering. The modelling simulations indicated that substitution of natural feedstocks by 15 wt% SFCC promotes the formation of reactive clinkers with more than 54% tricalcium silicate (C3S). Mixes with the potential to form the highest C3S were then produced, and heating microscopy fusibility testing was applied for evaluating the clinkers’ stability. The main factors governing the reactivity and stability of the clinker phases were the melt phase content, alumina modulus, and formation of C3S and dicalcium silicate (C2S). The self-pulverisation of clinker during cooling was observed in selected mixes, and it is potentially associated with high viscosity and low Fe content in the melt phase. The proposed framework enables optimisation of the dosing of raw meals containing alternative alumina-rich feedstocks for clinker production and allows a deeper interpretation of limited sets of empirical data.

Reusing spent fluid catalytic cracking catalyst as an adsorbent in wastewater treatment applications

Spent fluid catalytic cracking (FCC) catalyst is a waste from oil industry generated in very high amounts globally, being a major environmental burden as it is mostly landfilled. The direct use of this waste in wastewater treatment applications is rare, and the present study aims to fill the existing research gap. This is the first systematic investigation regarding the use of spent FCC catalyst as adsorbent material, for extracting methylene blue (MB) (pollutant model molecule) from wastewater.The effects of contact time (5 min–48 h), adsorbent dosage (0.5–3 g/L), adsorbate concentration (5–400 mg/L), and the reaction kinetics, were investigated. MB concentrations above 200 mg/L achieved a maximum uptake of 90.8 mg/g after 48 h. For MB concentrations below 10 mg/L, very fast dye removal was observed, reaching 100% after 1 h. The adsorption of MB followed a pseudo-second-order model (chemisorption), and the Langmuir model better described the experimental data (monolayer adsorption). The novel strategy here reported is aligned with key Sustainable Development Goals – 6, 9, 12 and 13 – and with the concept of the Circular Economy, and these results might add value to industrial waste whose availability is still expected to grow substantially soon.

G-C3N4/TiO2 for gas-phase formaldehyde photodegradation under visible light in the humidity control coatings

BackgroundsThe control of relative humidity and degradation of volatile organic compounds are regarded as major considerations in the enhancement of living quality in the indoor environment. From the viewpoints of circular economy, the valorization of inorganic wastes to prepare green building materials is crucial. MethodsFor the practical applications, the multifunctional coatings, applied in the indoor humidity control and photocatalytic degradation of formaldehyde, are prepared by recovering inorganic wastes (i.e., white carbon (WC) and spent fluid catalytic cracking catalysts (sFCCC)) and photocatalysts (graphitic carbon nitride/TiO2, denoted as GCN/TiO2) via a simple sol-gel method. Various physicochemical and analytic tools are used to characterize the coating properties and performance. Significant findingsCompared to commercial coatings, the prepared multifunctional coatings (i.e., W/B/S-47/47/6, where W, B and S represent the weight percentage (%) of white carbon, bassanite and sFCCC, respectively) have superior textural properties which can improve the buffering ability of indoor humidity. Moreover, the W/B/S-47/47/6 coatings exhibit the surpassing photodegradation of formaldehyde over commercial coatings by ca. 3 times. The higher charge transfer kinetics and greater thermodynamic driving force toward superoxide radical formation are responsible for the improved photocatalytic activity of W/B/S-47/47/6 coatings. According to the toxicity characteristic leaching procedure tests, no evident leaching heavy metals are observed, which provides an environmental-friendly and economical route for valorization of inorganic wastes.

Silica wastes derived multifunctional coatings for formaldehyde photodegradation and autonomous indoor humidity buffering

To maintain a comfortable and healthy indoor environment without large amounts of energy consumption is of great importance. The progress of multifunctional indoor coatings with formaldehyde photodegradation and humidity buffering capability is necessary. From the viewpoints of circular economy, the preparation of effective photocatalysts (denoted as sFCC/GCN-x and ESF/GCN-y) via the decoration of recycling industrial wastes (i.e., spent fluid catalytic cracking catalysts (sFCC) and enhancement silica fume (ESF)) onto graphitic carbon nitride (GCN) by using a simple route is reported. The obtained results show that the prepared sFCC/GCN-0.15 and ESF/GCN-0.15 photocatalysts have the rate constants of formaldehyde degradation of 0.0075 and 0.0082 min−1, respectively, which are superior to that of pristine GCN (0.0044 min−1) under visible-light irradiation. The enhanced transfer kinetics of photogenerated electrons and declined recombination of electron-hole pairs may account for the surpassing photocatalytic performance. Results obtained from electron paramagnetic resonance spectra and Mott-Schottky plots indicate that the formation of ･O2− via the reaction of O2 with electrons generated on the conduction band is the major reaction pathway to photodegrade formaldehyde under visible light. To further assess the real applications of prepared photocatalysts, the sFCC/GCN-0.15 and ESF/GCN-0.15 are used to fabricate the multifunctional coatings (denoted as s- and E-coatings) with sFCC and ESF as the main compositions. Experimentally, the E-coatings could reach the formaldehyde degradation efficiency of ca. 84.5% after 3 h of visible light irradiation and excellent humidity buffering ability (293.8 g m−2) which is at least 10-folds higher than commercial coatings (28.9 g m−2). This notable progress of humidity buffering capacity on E-coatings can be attributed to their surface textural properties. Most importantly, this study exemplifies the valorization of inorganic silica wastes to produce sustainable and multifunctional coatings which may offer the practical and cost-effective applications in the indoor living space.

Construction of a Multifunctional PCM@Catalyst Composite and Its Application in the Fluid Catalytic Cracking Process

Fluid catalytic cracking (FCC) is one of the most important processes in gasoline/diesel oil production, but the strong endothermic effect accompanied by this reaction often results in the deactivation of the catalyst. In this paper, a novel multifunctional phase change material (PCM)@Catalyst composite was designed and constructed, in which the PCM could be used to store waste heat and regulate the temperature for enhancing the catalytic efficiency of the FCC catalyst. Firstly, a core/shell Al-12wt%Si@Al2O3 was prepared via subsequent vapor treatment and high-temperature calcination of an Al-12wt%Si sphere. The Al species in the Al-12wt%Si served as the source of metal ions and was transformed in situ into a well-defined Al2O3 shell, which greatly improved the thermal stability and prevented the leaking of the Al-12wt% Si core in the high-temperature situation. The PCMs@Catalyst composite was then fabricated by casting the mixed powder of Al-12wt%Si@Al2O3 and Y zeolite into a granulated structure. The FCC results demonstrate that Al-12wt%Si@Al2O3/Y zeolite can optimize product distribution and reduce coke yield. This design concept and synthesis strategy can be extended to the production of a wide variety of hierarchical PCM@Catalyst composites for other reactions.

Spent fluid catalytic cracking catalyst derived MCM-41 supported polyethylenimine for post-combustion CO2 capture

The buildup of solid waste as well as the global warming has become one of the major challenges. CO2 capture with solid amine synthesized from solid waste can not only address the issue of large CO2 emissions, but also achieve efficient utilization of solid waste. In this work, spent fluid catalytic cracking catalysts (sFCCc), a type of major wastes in petrochemical industries, are first utilized to synthesize polyethyleneimine (PEI) functionalized ordered mesoporous materials. The as-obtained MCM-41-PEI from sFCCc exhibits an acceptable equilibrium CO2 capacity (qe) of 2.7 mmol/g in simulated flue gases (10 % CO2/N2) at 65 °C, which is higher than one prepared with commercial silicon source. Moreover, the adsorbent displays excellent cyclic stability during 50 TSA cycles in the dry simulated flue gases, where the capacity decreases only by 4.9 %. Additionally, the breakthrough capacity (qb) is significantly improved from 0.6 mmol/g to 1.6 mmol/g under humid conditions (35 °C, 10 % CO2/N2). Interestingly, we discover that the optimal adsorption temperature of MCM-41-PEI with different PEI loadings shifted due to the distinct PEI distribution behavior within the pores. The Avrami model provides a reliable interpretation for the CO2 adsorption behavior of MCM-41-PEI at various test conditions. The synthetic strategy here provides a new route in the treatment of excessive sFCCc resources to achieve valuable adsorbents, which can be applied to dilute source CO2 capture processes.

The Investigation of Zeolite to Matrix Ratio Effect on the Performance of FCC Catalysts during Catalytic Cracking of Hydrotreated VGO

Fluidized catalytic cracking of vacuum gas oil is considered a promising factor in enhancing the gasoline yield to fulfill global energy demands. In this study, a series of FCC catalysts with a zeolite to matrix ratio varying from 18 to 50 was prepared using USY zeolite and amorphous matrix. The matrix was composed of amorphous silica-alumina, kaolin, and silica sol binder. All fresh catalysts were subjected to hydrothermal deactivation treatment at 750 °C for 5 h. The performance evaluation of FCC catalysts was conducted in a fixed bed microactivity test unit, with vacuum gas oil as feed at 550 °C. Comparing a steamed CAT01 sample with a fresh CAT01, the surface area of the steamed sample was 23.3% less. Similarly, the fresh sample CAT05 acidity increased by 102% when compared with the fresh CAT01 sample. As the zeolite to matrix ratio increased, the selectivity of dry gas, LPG, and coke increased, associated with a consistent decrease in gasoline and heavy ends (LCO and HCO). The combined selectivity of product gasoline and LCO with low-zeolite steamed catalyst (CAT01) was 82%, and that of high-zeolite steamed catalyst (CAT05) was 76%. Furthermore, coke selectivity for the steamed CAT01 was 2.1%, whereas 3.7% was observed for the steamed CAT05 sample. The effect of the zeolite to matrix ratio was less pronounced in steamed catalysts as compared with fresh catalysts.

Study on pyrolysis characteristics, kinetics and thermodynamics of waste tires catalytic pyrolysis with low-cost catalysts

As a non-biodegradable solid waste, waste tires (WTs) have adverse effects on the ecological environment and human health. Waste tires are a good source of energy. In order to reduce the energy consumption of waste tires pyrolysis, this paper explores the influence of three low-cost catalysts on the catalytic effect of waste tires. The results of thermogravimetric experiments show that the use of spent FCC catalyst (FCC), red mud (Rm) and fly ash (Fa) during pyrolysis is beneficial to reducing the initial pyrolysis temperature of WTs. The kinetic calculation results show that compared with the direct pyrolysis of WTs, the average activation energy of WTs catalyzed by red mud and fly ash is reduced by about 9.5 kJ/mol and 7.8 kJ/mol, respectively. The average pre-exponential factor (lnA) decreased by about 1.3 min−1 and 1.4 min−1, respectively. The thermodynamic calculation results show that the endothermic reaction occurs in both the pyrolysis and catalytic pyrolysis of WTs, and the pyrolysis process cannot be carried out spontaneously. The pyrolysis reaction process of waste tires can be characterized by the combination of kinetics and thermodynamics, which provides parameters for determining the relevant process conditions for the industrialization of catalytic pyrolysis of waste tires.

High-Temperature Rheological Properties of Asphalt Mortar Modified with Spent FCC Catalysts

Spent fluid catalytic cracking catalysts (S-FCC-Cs) constitutes a fraction of the hazardous solid waste generated in the petrochemical industry. The resource application of S-FCC-Cs remains a challenge. This study aims to explore utilizing S-FCC-Cs in asphalt mortar as a means to enhance resource utilization. Five different S-FCC catalysts were used as substitutes for mineral powder in the asphalt slurry at varying proportions. The high-temperature rheology of the resulting spent FCC catalyst-modified asphalt slurry was analyzed using temperature scanning tests and multiple stress creep recovery (MSCR) tests conducted at different temperatures and substitution doping levels. As the proportion of alternative doping increased, both the phase angle and irrecoverable creep flexibility decreased, while the absolute values of the rutting factor, deformation recovery rate, and irrecoverable creep flexibility difference increased. Moreover, as the temperature rose, the phase angle increased while the rutting factor decreased. The inclusion of an alternative admixture significantly improved the high-temperature performance of the asphalt mastic. This improvement was attributed to several factors, including the increase in the elastic component, enhanced deformation resistance, and improved deformation recovery. While the high-temperature performance of spent FCC catalyst-modified asphalt mastic gradually declined with increasing test temperature, all performance indices remained superior to those of limestone mineral powder asphalt mastic. In addition, the asphalt mortar modified by S-FCC-C JX with a surface area and hydrophilic coefficient of 105 m2/g and 1.026, respectively, exhibited the best rutting resistance and resilience performances among the five mortars, suggesting that the two factors co-affected the high-temperature rheological properties of S-FCC-C asphalt mortar. Considering stress sensitivity, it is more advantageous in improving the high-temperature deformation resistance of asphalt slurry at the JX dosage of 20%. These research findings offer valuable guidance for the application of S-FCC catalysts in asphalt pavement.

Effect of spent fluid catalytic cracking (FCC) catalyst on syngas production from pyrolysis and CO2-assisted gasification of waste tires

With growing demands for improved energy recovery from waste tires, incorporating waste catalysts from different sectors can provide synergistic solution. This paper investigates the effect of using spent fluid catalytic cracking (FCC) catalyst on evolutionary behavior and yield of syngas (CO, H2, and light hydrocarbons), and char and energy yields during pyrolysis and CO2-assisted gasification of waste tires at 900 °C in a fixed-bed semi-batch reactor. The effect of catalyst position (in-situ and quasi-in-situ catalytic modes) and temperature was also examined during catalytic CO2-assited gasification for energy and chemicals production. The results reveal that the presence of spent FCC catalyst resulted in higher syngas and energy yields. The CO2-assisted gasification provided CO-rich syngas with higher yields than pyrolysis. The quasi-in-situ gasification provided increased syngas and energy yields by 24% and 23% respectively, as compared to in-situ catalytic gasification, which revealed that quasi-in-situ catalytic gasification to be more efficient and effective for increased syngas yields. Increasing temperature to 950 °C increased the yields syngas and energy owing to improved reforming and cracking reactions. This viability of utilizing spent FCC catalyst offers improved waste management economics for FCC plants while simultaneously improving the energy recovery from waste tires.

Maximizing High Value Light Products by Catalytic Cracking of VGO Produced by Iraqi Refinery over Formulated FCC Catalyst

Prototype of FCC catalyst were formulated by mixing the stabilised Y zeolites (68wt%) with polyvinal alcohol (PVA) (7%) as a solution binder and bentonite (25%). The Y zeolite including the original HY with Si/Al of 2.6 (cat.-2.6) and dealuminated HY with Si/Al of 30 (cat.-30) were used and tested for catalytic cracking of Iraqi vacuum gas oil (VGO) obtained from Al-Dura refinery using a pilot plant. The cracking process was carried out at a temperature of 520 °C and atmospheric pressure, The weight ratio of catalyst / oil ratio was 3 and 5. The results show that higher conversion of 77 wt. % and better product distribution (gasoline, kerosene and gas oil) could be obtained over cat.30 resulting to a good liquid product yield. The catalytic activity, in terms of VGO conversion was not affected over cat.-30 in spite of its lower acidity, suggesting the determinate of mesoporosity in the Y zeolite (cat.-30) catalysed cracking reactions. A higher yield of ~ 67 wt% to mid-distillates (i.e.Naphtha and kerosene) was as a result of the improvements in the diffusion to and from catalyst structure.

Influence of oxidative conditions on the deactivation of an equilibrium FCC catalyst in the fast pyrolysis of HDPE in a conical spouted bed reactor

This study approaches the continuous catalytic fast pyrolysis of plastics in a flexible and original technology, i.e., a conical spouted bed reactor equipped with fountain confiner and draft tube. The catalyst is an inexpensive equilibrium fluid catalytic cracking (FCC) one. Moreover, operation under oxidative conditions is proposed to solve heat supply to the pyrolysis reactor, as a previous study revealed a remarkable difference in the performance of the cracking catalyst when pyrolysis was carried out under inert (conventional) and oxidative conditions. Therefore, the aim of this paper is to assess the role played in the catalyst stability and deactivation mechanism by the presence of air in the reaction environment. A comparative study has been conducted by operating in long continuous runs under the same conditions (550 °C and a space time of 15 gcatalyst min gHDPE−1) in inert and oxidative atmospheres, i.e., equivalence ratios (ER) of 0 and 0.2, respectively. The evolution of product distribution with time on stream was evaluated. Moreover, samples of catalysts were taken from the reactor at different reaction times to correlate catalyst performance with the deactivated catalyst properties, and therefore progress in the understanding of the deactivation mechanism. The amount and nature of the coke deposited on the catalyst and its influence on catalyst properties was ascertained using thermogravimetry (TG-TPO), Raman spectroscopy, and NH3 and N2 adsorption–desorption techniques. The operation under oxidative conditions improved product distribution, with higher yields of light olefins. Moreover, catalysts activity and stability were also enhanced under oxidative conditions. Therefore, the results obtained involve a step forward towards the scaling up of plastics continuous catalytic pyrolysis.

Catalytic pyrolysis of waste composite plastics with waste FCC catalyst

The recycling of multilayer packaging plastic films is becoming more important due to its large application. In this work, two composite plastics of PET/LDPE (Polyethylene Terephthalate/Low Density Polyethylene) and PA6/LDPE (Polyamide/Low Density Polyethylene) were catalytically pyrolysed in different heating modes with the assistance of a waste FCC (fluid catalytic cracking) catalyst. The effect of FCC catalyst on product distribution, oil compositions and heteroatom compounds (oxygen and nitrogen-containing species) in different heating modes were studied using GC-MS (Gas Chromatograph - Mass Spectrometer) and APPI FT-ICR MS (Atmospheric Pressure Photoionization Fourier Transform-Ion Cyclotron Resonance Mass Spectrometer). It was found that waste FCC catalyst can form more gas at the expense of wax and oils due to its acidity property. More alkane and aromatic can be formed in the presence of FCC catalyst. Relative to non-catalytic pyrolysis, more alkanes are formed due to the hydrogen transfer ability of the FCC catalyst. The concentration of oxygen in oil and wax can be lowered by FCC catalyst. However, the concentration of nitrogen in oil is increased due to the lower denitrification ability of FCC catalyst even though its partition into oils is decreased. The waste FCC catalyst can decrease the number of O-containing compounds in heavier parts of oils from the fast pyrolysis of PET/LDPE. The number of compounds in Ox class are increased due to the interaction between oxygen radicals from PA6 and LDPE for the catalytic pyrolysis of PA6/LDPE.

Comparison of Two Lab Simulation Methods of Multiple Heavy Metal Contamination on FCC Catalysts

Qualitative and quantitative description are key to solving the problem of heavy metal contamination on fluid catalytic cracking (FCC) catalysts. The loading efficiencies for different metals were compared for the two lab simulation methods of Multi-Cyclic Deactivation (MCD) and Advanced Catalyst Evaluation (ACE), and the microcatalytic performance of metal-contaminated catalysts was evaluated using an ACE Model C device. The results show that the MCD and ACE methods both obtain extremely high data accuracy, indicating that they can be used to ensure the parallel reliability of experimental results. The typical operating parameters for hydrothermal aging and metals loading can be adjusted to suit different metal types and content targets for either of these two simulation methods. Compared with an equilibrium catalyst from an industrial unit, the MCD method has the advantages of basic hydrothermal aging treatment with less metal loading efficiency, while the ACE method has an accurate metal amount and high loading efficiency for metal contamination, with a metal balance recovery rate above 99.5% at similar activation to the equilibrium catalyst. When used with a reasonable and effective metal pretreatment scheme, these two laboratory simulation methods can be used to evaluate new commercial catalysts and in fundamental experiments for the improvement of FCC catalysts for removal of metal contamination.

Possible use of spent FCC catalyst for upgrading of wax from the pyrolysis of plastics to liquid fuel

The cracking of heavy wax derived from mixed plastics (high-density polyethylene, low-density polyethylene, and polypropylene) to chemical and fuel purposes was explored using spent fluid catalytic cracking catalyst (spent FCC). The wax cracking was performed by a fixed-bed pyrolysis reactor with a slow heating rate. All catalysts, when compared to other catalysts (HY zeolite and MCM-41), could enhance liquid oil and gas production. While the spent FCC catalyst produced the highest liquid oil with least amount of coke production. The influence of spent FCC catalyst ratio on product distribution revealed that a catalyst-wax ratio of up to 1:1 resulted in a higher liquid oil yield than a low ratio. Additionally, the increase of cracking temperature promoted more oil production; however, at high temperature (above 400 °C) the evaporation of wax became more significant, and consequently a high portion of produced wax was obtained. Therefore, under suitable conditions, the spent FCC catalyst demonstrated the possibility of upgrading the heavy wax into liquid fuels and chemicals. In addition, this study also compared the products obtained from two processing routes using the spent FCC catalyst. The first route involved the pyrolysis of plastics into wax and then cracking the wax into liquid fuel, while the second route involved a one-step process that directly converted plastics into liquid fuel. The spent FCC catalyst promoted the production of diesel-range hydrocarbons and suppressed the aromatic production for the wax cracking. By contrast, the spent FCC catalyst significantly enhanced aromatic production during the cracking of mixed plastics.