Spent Fluid Catalytic Cracking Catalyst Research Articles

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.

Study on synergistic pyrolysis and kinetics of mixed plastics based on spent fluid-catalytic-cracking catalyst

At present, disposable plastic products such as plastic packaging are very common in our daily life. These products are extremely easy to cause serious damage to the soil and marine environment due to their short design and service life, difficulties in degradation, or long degradation cycles. Thermochemical method (pyrolysis or catalytic pyrolysis) is an efficient and environmentally friendly way to treat plastic waste. In order to further reduce the energy consumption of plastic pyrolysis and improve the recycling rate of spent fluid catalytic cracking (FCC) catalysts, we adopt the "waste-to-waste" approach to apply the spent FCC catalysts as catalysts in the catalytic pyrolysis of plastics, exploring the pyrolysis characteristics, kinetic parameters, and synergistic effects between different typical plastics (polypropylene, low-density polyethylene, polystyrene). The experimental results show that the spent FCC catalysts used in the catalytic pyrolysis of plastics are beneficial to reduce the overall pyrolysis temperature and activation energy, in which the maximum weight loss temperature decreases by about 12℃ and the activation energy decreases by about 13%. The activity of spent FCC catalysts is improved after modification by microwave and ultrasonic, which further improve the catalytic efficiency and reduce the energy consumption of pyrolysis. The co-pyrolysis of mixed plastics is dominated by positive synergistic effect, which is conducive to improving the thermal degradation rate and shortening the pyrolysis time. This study provides relevant theoretical support for the resource application of spent FCC catalysts and "waste-to-waste" treatment of plastic waste.

Study on kinetics of spent FCC catalyst applied to the living waste plastics

AbstractThe thermochemical method is one of the most potential ways to treat waste plastics. In order to reduce the energy consumption of pyrolysis, this study selected spent fluid catalytic cracking (FCC) catalyst as a catalyst for pyrolysis of waste plastics to explore the pyrolysis process of mixed waste plastics (polypropylene (PP)/polyethylene (PE)/polystyrene (PS)). The kinetic calculations show that there was a positive synergistic effect in the co‐pyrolysis of mixed plastics, which was beneficial to the reduction of activation energy. However, the participation of spent FCC catalysts can further reduce the pyrolysis temperature and activation energy of plastics, and increase the thermal degradation rate. Compared with non‐catalytic pyrolysis, the pyrolysis temperature corresponding to the maximum weight loss rate during catalytic pyrolysis was about 12 K earlier, the maximum degradation rate was about 41% higher, and the average activation energy decreased by about 22 kJ/mol. In order to further improve the catalytic efficiency of spent FCC catalysts, the spent FCC catalysts were modified by ball milling or ultrasonic method and then used for plastic pyrolysis. It was found that the modification effect of ball milling method was better than that of the ultrasonic method. Through thermodynamic analysis, it was found that the endothermic reaction occurred in the process of plastic pyrolysis and could not proceed spontaneously. The formed pyrolysis products reduced the disorder of a microscopic system. Combined with the experimental results of this paper, it can provide theoretical support for the catalytic pyrolysis of spent FCC catalysts for mixed waste plastics.

Study on the Mechanism and Experiment of Styrene Butadiene Rubber Reinforcement by Spent Fluid Catalytic Cracking Catalyst

Spent Fluid Catalytic Cracking (FCC) Catalyst is a major waste in the field of the petroleum processing field, with a large output and serious pollution. The treatment cost of these waste catalysts is high, and how to achieve their efficient reuse has become a key topic of research at home and abroad. To this end, this paper conducted a mechanistic and experimental study on the replacement of some carbon blacks by spent FCC catalysts for the preparation of rubber products and explored the synergistic reinforcing effect of spent catalysts and carbon blacks, in order to extend the reuse methods of spent catalysts and reduce the pollution caused by them to the environment. The experimental results demonstrated that the filler dispersion and distribution in the compound are more uniform after replacing the carbon black with modified spent FCC catalysts. The crosslinking density of rubber increases, the Payne effect is decreased, and the dynamic mechanical properties and aging resistance are improved. When the number of replacement parts reached 15, the comprehensive performance of the rubber composites remained the same as that of the control group. In this paper, the spent FCC catalysts modified by the physical method instead of the carbon-black-filled SBR can not only improve the performance of rubber products, but also can provide basic technical and theoretical support to realize the recycling of spent FCC catalysts and reduce the environmental pressure. The feasibility of preparing rubber composites by spent catalysts is also verified.

Synthesis of biofuel via catalytic fast pyrolysis of wood-plastic composite over low-cost catalysts

Thermogravimetric (TG) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) analyses were performed to know the feasibility of low cost catalysts, γ-Al2O3, spent fluid catalytic cracking (FCC) catalyst, natural zeolite, to the pyrolysis of wood-plastic composite (WPC). Notably, the respective decomposition temperature of polyethylene and polypropylene in WPC was lowered with the use of low-cost catalysts during the catalytic fast pyrolysis (CFP). Furthermore, the lowest activation energy (Ea) of the CFP, obtained by the Ozawa method, was with the use of natural zeolite (127.5 kJ/mol), followed by the ones with the use of spent FCC catalyst (133.3 kJ/mol) and γ-Al2O3 (145.0 kJ/mol), respectively. In addition, the CFP over natural zeolite was less effective in terms of decreasing the production of low-quality hydrocarbons, paraffins and olefins having a wide carbon number distribution, and oxygenates compared to that over spent FCC catalyst and γ-Al2O3, respectively, due to the small pore size of natural zeolite. However, the largest amount of value-added aromatic hydrocarbons was produced in the CFP over natural zeolite among all the catalysts due to the high and strong acidity of natural zeolite.

Production and characterization of liquid oil from the pyrolysis of waste high-density polyethylene plastics using spent fluid catalytic cracking catalyst

Production and characterization of liquid oil from the pyrolysis of waste high-density polyethylene plastics using spent fluid catalytic cracking catalyst

Processing Mixture Of Polyethylene Terephthalate (PET) Plastic Waste and Oil Palm Empty Fruit Bunches by The Cracking Method

The composition of waste in Jambi City is dominated by plantation waste and plastic waste, if not managed properly, it can have a negative impact on the environment. There is a need for alternatives to processing plastic waste and plantation waste, one of which is the catalytic cracking process to produce alternative fuels. The catalyst used is petroleum refining industry waste that can be reused. This study aims to analyze the characteristics of FCC (Fluid Catalytic Cracking) catalysts and the effect of the ratio of Polyethylene Terephthalate (PET) plastic waste and Oil Palm Empty Fruit Bunches (OPEFB) on the percentage of products produced. The experimental design used in this study was a Complete Randomized Design (RAL) with variations in the ratio of PET plastic : oil palm empty fruit bunches, namely 1:0, 1:1, 1:2, and 1:3 at a temperature of 450°C and a time of 40 minutes. The results of the analysis showed that spent FCC catalysts were predicted to contain zeolite Y (rich in silica) which had a pore structure of different sizes, while the ratio of PET plastic waste and oil palm empty fruit bunches had a significant effect on the percentage of cracking liquid, charcoal, and gas. The 1:3 ratio treatment resulted in the highest percentage of cracking oil and charcoal at 27.85% and 34.41%. While the percentage of gas was the highest in the 1:0 treatment, which was 82.12%.
 Keywords: catalytic cracking, polyethylene terephthalate, plastic waste, biomass, empty bunches of palm oil, catalyst spent FCC

Catalytic removal of 2-butanone with ozone over porous spent fluid catalytic cracking catalyst

To remove harmful volatile organic compounds (VOCs) including 2-butanone (methyl ethyl ketone, MEK) emitted from various industrial plants is very important for the clean air. Also, it is worthwhile to recycle porous spent fluid catalytic cracking (SFCC) catalysts from various petroleum refineries in terms of reducing industrial waste and the reuse of discharged resources. Therefore, Mn and Mn–Cu added SFCC (Mn/SFCC and Mn–Cu/SFCC) catalysts were prepared to compare their catalytic efficiencies together with the SFCC catalyst in the ozonation of 2-butanone. Since the SFCC-based catalysts have a structure similar to that of zeolite Y (Y), the Mn-loaded zeolite Y catalyst (Mn/Y) was also prepared to compare its activity for the removal of 2-butanone and ozone to that of the SFCC-based ones at room temperature. Among the five catalysts of this study (Y, Mn/Y, SFCC, Mn/SFCC, and Mn–Cu/SFCC), the Mn–Cu/SFCC and Mn/SFCC catalysts showed the better catalytic decomposition activity than the others. The increased distributions of the Mn3+ species and the Ovacancy sites in Mn/SFCC and Mn–Cu/SFCC catalysts which could supply more available active sites for the 2-butanone and ozone removal would enhance the catalytic activity of them.

Synthesis of nickel powder with good hydrogen evolution performance from spent Fluid Catalytic Cracking catalysts

The strategic metals in spent Fluid Catalytic Cracking (FCC) catalysts have attracted worldwide attention. In this work, the recovery of rare earths (lanthanum and cerium), nickel and vanadium have been achieved by acid leaching, extraction and precipitation, while the high-purity nickel powder with pretty hydrogen evolution performance has been synthesized for value-added utilization. Secondary leaching has been used for insoluble Ni power, and the total leaching rates of Ce, La, V and Ni are 96.17%, 85.86%, 99.99% and 74.62%, respectively. Rare earths have been recovered by the precipitation in primary leaching solution. The recovery rate of La is 97.11% and Ce is 99.96%. In secondary leaching solution, the impurity removal has been conducted, and the removal rate of Al and Fe is above 99.9%. Then the V and Ni are separated by solvent extraction, the extraction rate of V by N235 is 97.57%, the separation factor of Ni and V is 634.61. Finally, the high-purity NiSO4 solution(99.62%)is reduced to nickel power by the reducing agent N2H4·H2O, which was made for the hydrogen evolution reaction catalyst. When the current density is 10 mA/cm2, the overpotential is 308 mV, and the slope of Tafel is 128 mV·dec−1. This process provides a comprehensive recovery route of valuable metals from spent FCC catalysts for new energy industry.

Oxidative Fast Pyrolysis of High-Density Polyethylene on a Spent Fluid Catalytic Cracking Catalyst in a Fountain Confined Conical Spouted Bed Reactor.

The oxidative fast pyrolysis of plastics was studied in a conical spouted bed reactor with a fountain confiner and draft tube. An inexpensive fluid catalytic cracking (FCC) spent catalyst was proposed for in situ catalytic cracking in order to narrow the product distribution obtained in thermal pyrolysis. Suitable equivalence ratio (ER) values required to attain autothermal operation were assessed in this study, i.e., 0.0, 0.1, and 0.2. The experiments were carried out in continuous regime at 550 °C and using a space-time of 15 gcatalyst min gHDPE -1. The influence of an oxygen presence in the pyrolysis reactor was analyzed in detail, with special focus on product yields and their compositions. Operation under oxidative pyrolysis conditions remarkably improved the FCC catalyst performance, as it enhanced the production of gaseous products, especially light olefins, whose yields increased from 18% under conventional pyrolysis (ER = 0) to 30% under oxidative conditions (ER = 0.1 and 0.2). Thus, conventional catalytic pyrolysis led mainly to the gasoline fraction, whereas light olefins were the prevailing products in oxidative pyrolysis. Moreover, the oxygen presence in the pyrolysis reactor contributed to reducing the heavy oil fraction yield by 46%. The proposed strategy is of great relevance for the development of this process, given that, on one hand, oxygen cofeeding allows solving the heat supply to the reactor, and on the other hand, product distribution and reactor throughput are improved.

Study on pyrolysis behavior and kinetics of waste plastics with spent FCC catalyst

AbstractPyrolysis is the most promising method for treating plastic waste since it can convert waste plastics into high value‐added products, which have significant application potential. In this study, kinetic and thermodynamic analyses of spent fluid catalytic cracking (FCC) catalysts were performed for testing their applicability in catalytic cracking of mixed plastics. Thermogravimetric analysis data were obtained at different heating rates under an inert atmosphere, and the synergistic effect between the mixed plastics and activation energy reduction before and after pretreatment of the spent FCC catalysts was discussed. Through a variety of model‐free methods (Flynn‐Wall‐Ozawa, Kissinger‐Akahira‐Sunose, Starink, and Kissinger methods), it is proved that the spent FCC catalyst facilitates the reduction in activation energy required for the pyrolysis of plastics, which is reduced by approximately 13% from 278 to 242 kJ/mol. The catalytic performance of spent FCC catalyst was improved after pretreatment, while its activation energy decreased by approximately 21% from 278 to 220 kJ/mol. The Friedman‐Reich‐Levi method was used to fit the curve, and the number of mechanism functions in plastic pyrolysis was determined according to the slope of the fitting curve. The C‐R method was used in combination with the Malek method to determine the optimal mechanism function. Moreover, kinetic parameters of the spent FCC catalyst for catalytic cracking of plastics were obtained via kinetic studies on the pyrolysis of mixed plastics, which provided theoretical guidance for industrialization of plastic pyrolysis.

Intensifying gasoline production in the hydrocracking of pre-hydrotreated light cycle oil by means of Pt and Pd supported on a spent FCC catalyst

Motivated by the necessity of intensifying the valorization of secondary refinery streams and of extending the life cycle of the catalysts, this study aims to obtain high quality gasoline in the hydrocracking of a pre-hydrotreated light cycle oil (HT-LCO) using noble metals catalysts supported on a spent fluid catalytic cracking (FCC) catalyst. Hydrocracking runs have been carried out in a fixed bed reactor with two different catalysts (Pt/FCC and Pd/FCC) under the following conditions: 320–400 °C; 80 bar; hydrogen to HT-LCO ratio, 1000 NmL mL−1; weight hourly space velocity (WHSV), 4.48 h−1; and time on stream (TOS), 8 h. The results have exposed that 400 °C is the optimal temperature for hydrocracking the HT-LCO, since the yield of gasoline is clearly maximized (yielding up to 80 wt%) at the same time that the formation of gases is minimized. Comparing both catalysts, the Pt/FCC catalyst has offered better performance as its high hydrogenation capacity has allowed for obtaining an isoparaffinic gasoline fraction with a RON of 93.0. These good results lay on two facts that avoid the blocking of the micropores of the zeolite HY by the deposition of coke: (i) the hydrocracking of the coke precursors; and (ii) the matrix of the FCC catalyst where a fraction of the coke is deposited. In this way, after an initial deactivation period, the catalysts have reached a pseudo-stable state with a notorious remaining catalytic activity (higher for the Pt/FCC catalyst).

Waste resource utilization: Spent FCC catalyst-based composite catalyst for waste tire pyrolysis

• Composite FCC catalysts were used to improve waste tire pyrolysis product yields. • CaO or heavy oil could enhance the catalytic pyrolytic effect of FCC catalysts. • Heavy oil enhances interactions between the spent FCC catalysts and waste tires. • CaO decreases the sulfur contents of the final tire pyrolysis oil products. • Proposed composite catalysts extend the application of pyrolysis to waste tires. Waste tires are complex organic materials composed of various rubbers and fillers. Spent fluid catalytic cracking (FCC) catalysts cannot efficiently catalyze the pyrolysis of all organic components in waste tires. In this study, we attempted to improve the yield and quality of products obtained from the pyrolysis of waste tires. To this end, we prepared two composite catalysts (i.e., spent FCC catalysts + heavy pyrolysis oil and spent FCC catalysts + calcium oxide) with spent FCC catalysts as the main component, and studied their synergistic effects on the catalytic pyrolysis of the tires. In this study, the composite catalyst improved the recovery volume of the pyrolysis oil at 205 and 360 °C and increased the BTEX content in the oil by 14.7% and 8%, respectively. The experimental results showed that the heavy oil component in the composite catalyst enhanced interactions between the spent FCC catalysts and waste tires, thereby improving the yield and quality of tire pyrolysis oil (TPO). The alkaline material in the composite catalyst played a role in sulfur fixation and reduced the sulfur content of the TPO. The application of spent FCC catalysts to waste tire pyrolysis can meet the demand for low-cost catalysts for waste tires and improve the quality of the resulting TPO. Our findings collectively reflect the economic and social benefits of using composite catalysts for waste tire pyrolysis.

Synthesis and hydration of ye’elimite-containing cement (YCC) produced with spent fluid catalytic cracking catalyst

The consumption of petroleum products from fluidized bed catalytic cracking (FCC) units has increased worldwide. One of the primary materials used in this process is the zeolitic catalyst which loses its catalytic capacity over time, generating the spent FCC catalyst – SFCC. This work evaluated the feasibility of using SFCC as raw material for ye'elimite-containing cements (YCC) production. Specifically, six types of clinkers were synthesized in the laboratory, varying the ye’elimite content, with and without SFCC. Powder and in-situ X-ray diffraction (XRD), isothermal calorimetry, and thermogravimetric analysis (TGA) were conducted in anhydrous and hydrated samples. Clinkers with SFCC stabilized more C4AF than those without SFCC; so there was less Fe3+ available in these systems than in the reference systems to stable the pseudo cubic ye'emelite. As a result, the SFCC-containing cements (with more orthorhombic ye’elimite) had higher reaction rates within the first 12–20 h of hydration. In turn, the higher ye’elimite contents in the high- and medium-ye’elimite reference clinkers led to the further formation of hydrated phases at 28 days of hydration on these samples. The equivalent ye’elimite content in low-ye’elimite clinkers led to equivalent cumulative heat and phase assemblage from 48 h to 28 days. Overall, the use of SFCC allowed to incorporate of up to 20.81 wt% of the residue in raw material replacement, resulting in cements with increased early-age reactivity.

Alkali-excited gel structure and compositions evolution in geopolymers synthesized from the spent FCC catalyst and steel slag

The effect of the alkaline activation process, especially the SiO2/Na2O molar ratio (Ms) in the prepared alkaline activator, on the geopolymer materials prepared using the spent fluid catalytic cracking (FCC) catalyst and steel slag as raw materials is investigated in this study. The results indicate that the compressive strength of prepared geopolymers has been greatly affected by the alkaline environment. The compressive strength of obtained samples is improved obviously in the strong alkaline environment. Meanwhile, the number of amorphous gels in the prepared geopolymers increased with Ms decreasing. It is conducive for the silicon-oxo-aluminate species in the oligomers to polymerize into polymers with 3D polymeric structures, which would lead to the surface of as-prepared samples becoming smoother and the structure becoming denser. Moreover, the strong alkaline environment is beneficial for Ca2+ to involve in the geopolymerization reaction and form the N(C)ASH gel, which can further enhance the compressive strength of the prepared geopolymer.

Study of waste rubber catalytic pyrolysis in a rotary kiln reactor with spent fluid-catalytic-cracking catalysts

The low utilization rate of waste rubber has caused serious environmental pollution problems. Catalytic pyrolysis is an effective method for ensuring the resource utilization of waste rubber. However, the high cost and nonrecyclability of the used catalysts complicate the utilization of this method in industrial applications. In this paper, the spent fluid-catalytic-cracking (FCC) catalysts were applied into pyrolysis of waste rubber, aiming to reduce the cost of catalytic pyrolysis of waste rubber. At the same time, the pyrolysis mechanisms of the spent FCC catalysts used in waste rubber were studied. Pyrolysis/catalytic pyrolysis experiments on single-rubber-type unvulcanized rubber, single-rubber-type vulcanized rubber, and tread compounds were performed in a self-developed industrial pilot plant. The experimental results showed that the pyrolysis oil yield of the spent FCC catalysts catalyzed pyrolysis of the waste rubber increased and the content of light aromatics in increased by more than 90 %, indicating that the spent FCC catalysts applied in waste rubber can improve the quality of pyrolysis products, increase production efficiency, and realize the collaborative high-value reuse of waste rubberand spent FCC catalysts.

Selective Leaching of Valuable Metals from Spent Fluid Catalytic Cracking Catalyst with Oxalic Acid

The problem of spent fluid catalytic cracking (SFCC) catalyst resource utilization, draws more and more attention to system analysis. SFCC was leached in an oxalic solution for comprehensive utilization. The results showed that for a D50 ≤ 17.34 μm, the catalyst leached for 240 min at 95 °C in the presence of a 2 mol/L oxalic acid solution, and the extent of leaching of V, Ni, Fe, and Al was 73.4%, 32.4%, 48.2%, and 36.8%, respectively. Studies on the occurrence state of the main ions (V, Ni, Fe, and Al) in the leaching solution were presented. Additionally, the separation of the main ions from such a solution by the “solvent extraction-stripping-hydrothermal precipitation-comprehensive recovery of valuable metal” process was studied. The immobilization rates of vanadium and nickel in geopolymers can be obtained using the toxicity characteristic leaching procedure (TCLP) test, and the geopolymers prepared by SFCC leaching residues can be considered a non-hazardous material. A process diagram of the comprehensive utilization of SFCC catalysts is presented.

Combined Activated Carbon with Spent Fluid Catalytic Cracking Catalyst and MgO for the Catalytic Conversion of Waste Polyethylene Wax into Diesel-like Hydrocarbon Fuels.

Catalytic pyrolysis of polymer waste is an attractive alternative process for the conversion of large hydrocarbon compounds to useful products for the most reliable fueling and valuable chemicals, growing toward a circular economy and enhancing the reduction of waste materials. In this study, catalytic pyrolysis of waste polyethylene wax (WPEW) using a dual acid–acid catalyst and acid–base catalyst, which had various pore size distributions and included a strong active site, maximized the desirable yield and product distribution. The effect of the process conditions and synergy of activated carbon (AC) blended into both a spent fluid catalytic cracking catalyst (FCC) and magnesium oxide (MgO) catalyst was examined in a 3000 cm3 custom-built reactor at varying operating temperatures (400–470 °C), inert nitrogen gas flow rates (50 mL min–1), catalyst loading (1–5 wt %), and FCC-AC and MgO-AC ratios in the catalytic conversion of WPEW to obtain the highest amount of diesel-like oil. The results indicated that thermal cracking of WPEW at 420 °C by a fixed inert N2 flow rate of 50 mL min–1 obtained the highest liquid yield of 81.64 wt % and a diesel-like fraction of 35.51 wt %, while the catalytic conversion of WPEW under optimum conditions (temperature: 420 °C; fixed inert N2 flow rate: 50 mL min–1; catalyst load: 5 wt %; MgO-AC ratio: 0.5:0.5) achieved the highest liquid diesel-like yield of 41.92 wt %. Physicochemical analyses showed that the highest heating value of WPEW pyrolytic oil was 44.20 MJ kg–1, and the viscosity was 1.7 mm2 s–1 at 40 °C. The combination of MgO-AC as a dual catalyst illustrates a positive synergistic effect on the catalytic activity performance markedly, outstanding catalytic characteristics alongside high selectivity in pyrolysis of WPEW to paraffinic hydrocarbons in the diesel-like fraction.

Catalytic pyrolysis of chicken manure over various catalysts

In this study, non-catalytic and catalytic pyrolysis of chicken manure (CM) were investigated to understand the pyrolysis kinetics and product distribution of CM by thermogravimetric analysis (TGA) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). TGA and the apparent activation energy changes, calculated using the Ozawa method, indicated that the decomposition of CM was comprised of four reaction stages. The 1st decomposition of CM was likely the decomposition of carbohydrates and lipids, followed by the 2nd decomposition of lignin at high temperatures. The 3rd decomposition was likely involving the decomposition of proteins. At the final stage, metal carbonates in the ash of CM were likely decomposed. Py-GC/MS analysis indicated a decrease in oxygenates, such as furfural, phenol, and fatty acid, after applying acid catalysts. Among the various acid catalysts, HZSM-5(Silica/Alumina = 30), having the strongest acid sites, showed the highest efficiency for the production of aromatic hydrocarbons, followed by HBeta(Silica/Alumina = 25), HY(Silica/Alumina = 30), natural zeolite, spent fluid catalytic cracking catalyst (FCC), and bentonite. Although bentonite and spent FCC were ineffective, natural zeolite showed a catalytic effect on converting oxygenates to aromatic hydrocarbons. On the other hand, the content of a high molecular weight nitrile, hexadecanenitrile, was also increased. Commercial zeolites, HY(Silica/Alumina = 30), HBeta(Silica/Alumina = 25), and HZSM-5(Silica/Alumina = 30), led to higher aromatic formation efficiencies with less hexadecanenitrile formation than other catalysts. These efficiencies were increased significantly by varying the catalyst to CM ratio from 1/1 to 5/1, with a noticeable decrease in hexadecanenitrile.

Kinetics of Ni, V and Fe Leaching from a Spent Catalyst in Microwave-Assisted Acid Activation Process.

Ni, V and Fe are the main contaminant metals that lead to the deactivation of the spent fluid catalytic cracking (SFCC) catalyst. In this work, the properties and distribution of Ni, V and Fe in the SFCC catalyst are investigated by employing EPMA-EDX, SEM and XPS techniques. The kinetics of Ni, V, Fe and Al leaching in organic and inorganic acids are studied under microwave heating. The EPMA-EDX results show that Fe and Ni mainly accumulate near the particle surface, while V eventually distributes throughout the catalyst particle. The XPS result suggests that the phase speciations of Ni in the SFCC catalyst are Ni, Ni2SiO4 and NiAl2O4, while Fe is present in a mixture of Fe3O4, Fe2O3 and Fe2SiO4. V is in the forms of V2O5 and VO2. Compared with oxalic acid, sulfuric acid has a better removal effect of contaminant metals, especially for Ni. The leaching kinetics results indicate that using either sulfuric acid or oxalic acid, the apparent activation energy of V is obviously lower than that of Fe and Ni, and the priority of the three contaminant metals in the removal effect is V > Fe > Ni. In addition, the leaching kinetics of contaminant metals in the microwave-assisted acid activation process are controlled by the surface chemical reaction control model.