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13 C NMR spectra of hexane soluble extractives and virgin olive oil: a) hexane soluble extractives, b) virgin olive oil.
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Olive mill wastewater sludge (OMWS) is an environmental pollutant in olive oil industry. The problem stems from the strong odor and poor biodegradability of OMWS because of its high phenolic compounds. In most Mediterranean countries, olive mill wastewater is stored in evaporation ponds and the residual sludge is landfilled for disposal. To address...
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... oxygenated aliphatic compounds region (50-110 ppm) showed very weak resonances compared to those observed for the hexane extract (Figure 1a) suggesting that some of the glycerol, alcoholic, and sterol compounds were converted to other compounds during the pyrolysis. Although there were weak signals in the 50-110 ppm region for the sand pyrolysis oils at 450°C, in the case of the red mud pyrolysis oils, there were no signals. This clearly showed that the red mud was effective in deoxygenating these compounds or converted them into coke or gas. In the olefinic and aromatic carbons region of the spectra (110-160 ppm), the olefinic signals at 129-130 ppm were more intense for the sand pyrolysis oils relative to the red mud pyrolysis oils, which indicate that the sand was not effective in converting the double bond compounds, whereas the red mud broke some of these bonds and/or converted them into aromatic compounds through dehydrogenation and cyclization. The semi-quantitative integration of the 13 C NMR data showed that at similar pyrolysis temperatures, the aromatic compounds produced with the red mud were twofold higher than that produced using the ...
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... acid number of the HE was 129 mgKOH/ (g extract); the saponification value was 217 mgKOH/ (g extract) and the calculated FFA was 65% (Table 1). The ester value was 88 and the glycerine value was 4.81%. Thus, it is clear from the above values that the HE which constituted 41% of the OMWS was rich in FFA and low in glycerine probably because of the degradation during storage in the pond. The predominant FFA groups detected by GC/MS analysis of the HE were oleic and palmitic acids, which is similar to the findings of Saiz-Jaminez et al. [32]. The major compounds detected in the ethanol extract were glycerol, 2-methyl-1,3-cyclohexanedione and 4- hydroxy-benzeneethanol, which clearly indicated that some of the triglycerides had been hydrolyzed into FFA and glycerol. The unsaponifiable material content was relatively low (7.2 mass%). The 13 C NMR analysis of the HE showed strong signals for aliphatic carbons (Figure 1a) and comparison of the 13 C NMR spectrum with that of virgin olive oil (Figure 1b) confirmed the presence of acylglycerides in this extract. Additionally it appeared the HE also contained some sterols which were also detected in minor concentrations using GC/MS analysis. The four functional groups typical of virgin olive oil were identified in the HE; this included carbonyl compounds between 172 ppm and 180 ppm that correspond to monoacylglycerides (MAG), diacylglyderides (DAG), triacylglycerides (TAG), and FFA. The FFA signal at 180 ppm was very weak whereas, the glycerol ester carbon signals at 172 ppm due to MAG, DAG, and TAG were relatively stronger, but compared to virgin olive oil (Figure 1b), these peak intensities were very weak and indicates that the residual amount of acylglycerides was very low. Most of the signals appeared to be due to MAG and DAG according to assignments by Sacchi et al. [33] with very little contribution from TAG. The lipids content of olive mill wastewater is usually very low ranging from 1.6 to 9.8 g/L [34], which appeared to support the weak signals observed for the HE. Further, it was reported that fats and carbohydrates in olive mill wastewater degraded when they were stored and converted to sludges in open ponds [3], but Saiz-Jimenez et ...
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... acid number of the HE was 129 mgKOH/ (g extract); the saponification value was 217 mgKOH/ (g extract) and the calculated FFA was 65% (Table 1). The ester value was 88 and the glycerine value was 4.81%. Thus, it is clear from the above values that the HE which constituted 41% of the OMWS was rich in FFA and low in glycerine probably because of the degradation during storage in the pond. The predominant FFA groups detected by GC/MS analysis of the HE were oleic and palmitic acids, which is similar to the findings of Saiz-Jaminez et al. [32]. The major compounds detected in the ethanol extract were glycerol, 2-methyl-1,3-cyclohexanedione and 4- hydroxy-benzeneethanol, which clearly indicated that some of the triglycerides had been hydrolyzed into FFA and glycerol. The unsaponifiable material content was relatively low (7.2 mass%). The 13 C NMR analysis of the HE showed strong signals for aliphatic carbons (Figure 1a) and comparison of the 13 C NMR spectrum with that of virgin olive oil (Figure 1b) confirmed the presence of acylglycerides in this extract. Additionally it appeared the HE also contained some sterols which were also detected in minor concentrations using GC/MS analysis. The four functional groups typical of virgin olive oil were identified in the HE; this included carbonyl compounds between 172 ppm and 180 ppm that correspond to monoacylglycerides (MAG), diacylglyderides (DAG), triacylglycerides (TAG), and FFA. The FFA signal at 180 ppm was very weak whereas, the glycerol ester carbon signals at 172 ppm due to MAG, DAG, and TAG were relatively stronger, but compared to virgin olive oil (Figure 1b), these peak intensities were very weak and indicates that the residual amount of acylglycerides was very low. Most of the signals appeared to be due to MAG and DAG according to assignments by Sacchi et al. [33] with very little contribution from TAG. The lipids content of olive mill wastewater is usually very low ranging from 1.6 to 9.8 g/L [34], which appeared to support the weak signals observed for the HE. Further, it was reported that fats and carbohydrates in olive mill wastewater degraded when they were stored and converted to sludges in open ponds [3], but Saiz-Jimenez et ...
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... acid number of the HE was 129 mgKOH/ (g extract); the saponification value was 217 mgKOH/ (g extract) and the calculated FFA was 65% (Table 1). The ester value was 88 and the glycerine value was 4.81%. Thus, it is clear from the above values that the HE which constituted 41% of the OMWS was rich in FFA and low in glycerine probably because of the degradation during storage in the pond. The predominant FFA groups detected by GC/MS analysis of the HE were oleic and palmitic acids, which is similar to the findings of Saiz-Jaminez et al. [32]. The major compounds detected in the ethanol extract were glycerol, 2-methyl-1,3-cyclohexanedione and 4- hydroxy-benzeneethanol, which clearly indicated that some of the triglycerides had been hydrolyzed into FFA and glycerol. The unsaponifiable material content was relatively low (7.2 mass%). The 13 C NMR analysis of the HE showed strong signals for aliphatic carbons (Figure 1a) and comparison of the 13 C NMR spectrum with that of virgin olive oil (Figure 1b) confirmed the presence of acylglycerides in this extract. Additionally it appeared the HE also contained some sterols which were also detected in minor concentrations using GC/MS analysis. The four functional groups typical of virgin olive oil were identified in the HE; this included carbonyl compounds between 172 ppm and 180 ppm that correspond to monoacylglycerides (MAG), diacylglyderides (DAG), triacylglycerides (TAG), and FFA. The FFA signal at 180 ppm was very weak whereas, the glycerol ester carbon signals at 172 ppm due to MAG, DAG, and TAG were relatively stronger, but compared to virgin olive oil (Figure 1b), these peak intensities were very weak and indicates that the residual amount of acylglycerides was very low. Most of the signals appeared to be due to MAG and DAG according to assignments by Sacchi et al. [33] with very little contribution from TAG. The lipids content of olive mill wastewater is usually very low ranging from 1.6 to 9.8 g/L [34], which appeared to support the weak signals observed for the HE. Further, it was reported that fats and carbohydrates in olive mill wastewater degraded when they were stored and converted to sludges in open ponds [3], but Saiz-Jimenez et ...
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Environmental problems have encouraged investigation of renewable energies. The organic waste treating through fast pyrolysis seems to be a highly promising option for decreasing pollutants. Olive pomace, a major source of waste in countries with high production of olive oil (mainly Spain, Italy, and Greece), is a clear target for valorisation. Dri...
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... This is mainly attributed to its characteristic physicochemical nature, known for its complex physical properties and high organic pollutant content. Various biological and combined process technologies have been explored to mitigate OMWS pollutants, including composting, vermicomposting, pyrolysis, solar drying, and microbial inoculation (Agblevor et al., 2017;Bouhia et al., 2022c;Grioui et al., 2019;Hytiris et al., 2004;Martínez-Gallardo et al., 2020). Aerobic processes have consistently shown promising results, being low-cost, eco-friendly, and easily scalable (Bouhia et al., 2022b;Muñoz-Palazon et al., 2019). ...
Olive mill wastewater sludge (OMWS) represents a residual pollutant generated by the olive oil industry, often stored in exposed evaporation ponds, leading to contamination of nearby land and water resources. Despite its promising composition, the valorization of OMWS remains underexplored compared to olive mill wastewater (OMW). This study aims to identify potent native microbial species within OMWS suitable for bioremediation and its transformation into a high-value organic fertilizer. The microbial screening, based on assessing OMWS tolerance and phosphate solubilization properties in vitro, followed by a singular inoculation using a mixture of OMWS and rock phosphate (RP). Identification of FUN 06 (Galactomyces Geotrichum), a fungal species, employed as an inoculant in the treatment of sterile OMWS supplemented with RP. Results demonstrate that fungal
inoculation notably diminished OMWS phytotoxicity while enhancing its physicochemical parameters, nutrient concentrations, and removal of toxic organic compounds by up to 90% compared to the control, and enhances plant growth, offering a sustainable approach to tackle environmental concerns. Additionally, metataxonomic analysis unveiled FUN 06’s propensity to enhance the presence of microbial species engaged in pollutant degradation. However, higher RP dosage (10%) appeared to adversely affect bioprocess efficiency, suggesting a potential dose-related effect. Overall, FUN 06, isolated from OMWS evaporation ponds, shows promise for effective bioremediation and sustainable reuse. In fact, our results indicate that targeted microbial inoculation stands as an effective strategy for mitigating pollutants in OMWS, facilitating its conversion into a nutrient-rich
organo-mineral fertilizer suitable for direct use, promoting its beneficial reuse in agriculture, thereby presenting a promising avenue for olive oil waste management
... Moreover, OMWS has a relatively high heat value (HHV) of approximately 25 MJ kg -1 , which can result in high-quality liquid biofuel using optimal pyrolysis conditions. Recently, the fast pyrolysis of OMWS was investigated for bio-oil production, and a patent has been proposed (Agblevor and Halouani, 2015;Ma and Agblevor, 2016;Agblevor et al., 2017). The obtained product was a relatively high-quality biofuel compared with Petro-diesel in terms of HHV, pH, and water content. ...
... The obtained product was a relatively high-quality biofuel compared with Petro-diesel in terms of HHV, pH, and water content. Nevertheless, the viscosity and oxygen content of the obtained bio-oil was relatively high, which needs to be improved (Agblevor et al., 2017). This problem was resolved by (Ma and Agblevor, 2016) using HZSM-5 catalytic fast pyrolysis followed by hydrodeoxygenation. ...
Olive mill wastewater sludge (OMWS) is a by-product of the olive extraction process that is attracting substantial attention due to its extremely hazardous effects on aquatic and terrestrial ecosystems. OMWS is a product of the common disposal method of olive oil mill wastewater (OMWW) that accumulates in evaporation ponds. It is estimated that approximately 10 × 10 6 m 3 of OMWS is generated worldwide each year. OMWS is characterized by its significantly variable physicochemical properties and organic pollutant constituents, such as phenols and lipids, which are dependent upon the environmental features of the receiving ponds. Nonetheless, many related studies have recognized the biofertilizer potential of this sludge owing to its high mineral nutrient and organic matter load. OMWS exhibits promising valorization potential in several fields, including agriculture and energy production. Compared to those of OMWW, studies of OMWS are still lacking concerning its composition and characteristics, which are necessary for the future implementation of efficient valorization strategies. The main purpose of this review paper is to fill the gap that exists in the literature by providing a critical analysis of the available data on OMWS production, distribution, characteristics, and properties. Additionally, this work sheds light on important factors affecting OMWS properties, including the variability of the indigenous microbial communities regarding bioremediation. Finally, this review addresses the current and future valorization routes, from detoxification to the development of promising applications in agriculture, energy, and the environment, which could have significant socioeconomic implications for low-income Mediterranean countries.
... Hytiris et al. [23], have suggested the solidification of this sludge after mixing with cement, Paredes et al. [24], have studied its co-composting with agricultural waste concluding that it could be viable environmentally-friendly approach, while an earlier study by Saiz-Jimenez et al. [25], proposed the use of OMWWS as a soil fertilizer. More recent studies have considered the thermochemical conversion (slow and fast pyrolysis) of OMWWS with the aim of creating bio-fuels [26,27]. ...
... Pyrolysis of OMWWS, using sand and red mud respectively, was recently investigated showing that low viscosity, low density and high HHV oils can be produced from this feedstock. Especially using a basic catalyst (red mud) led to the production of a bio-oil of higher quality than biodiesel, with much lower oxygen content and high aliphatic hydrocarbon content as compared to most lignocellulosic biomass pyrolysis oils [26,27]. However, OMWWS still contains valuable micronutrients, fats and possibly certain polyphenolic compounds with bioactive properties [32]. ...
... MgO and ZSM-5 were used as received or further promoted with Co (5% wt.). In addition to MgO, SiO 2 (purchased from MERC) and a commercial alumina support (purchased from SASOL) were also selected and studied as potential catalysts for biomass catalytic pyrolysis of OMWWS, as aluminum oxide, magnesium oxide, and silicon oxide, are low-cost catalytic materials and among the major components of red mud, an effective catalyst recently used in the pyrolysis of OMWWS [26]. MgO, SiO 2 and Al 2 O 3 were also tested either as received or further promoted with Fe or Mn (10 and/or 20% wt.) ...
... In this study, we propose to develop an Aspen Plus model which takes into account the global kinetic parameters for the production of pyrolytic bio-oil from fast pyrolysis of OMWS (catalytic and noncatalytic) and compare the simulation results with the experimental data of Agblevor et. al. [34]. After validation of results, the model is upscaled to commercial scale of 100 tonnes/day and two schemes are proposed. ...
... Experiments were performed by Agblevor et. al. [34] in Utah State University. Olive mill wastewater sludge (OMWS) was collected from a Tunisian evaporation pond. ...
... The reaction rate of the pyrolysis of OMWS is determined from the analysis of experimental data of Agblevor et. al. [34] and formulated according to the modified Arrhenus law proposed by Diaz and Broun [41]. ...
A techno-economic analysis of production of bio-oil from catalytic pyrolysis of olive mill wastewater sludge has been performed with two different cooling schemes. The two configurations differ in the manner how the bio-oil vapors are quenched. In scheme-1, a vapor compression refrigeration machine is utilized for condensation of bio-oil vapors while in scheme-2, the vapor compression refrigeration machine is replaced by absorption refrigeration machine. The two schemes are modelled in Aspen Plus which provides mass and energy balances. For techno-economic analysis, Aspen process economic analyzer is employed. The model is first validated against experimental data from lab scale and then upscaled to an industrial scale of 100 tonnes/day wet biomass (93 tonnes/day dry biomass). Results show that the model with absorption refrigeration machine (scheme-2) has a slightly better process efficiency and a lower MFSP compared to the model with compression refrigeration machine (scheme-1). Total anticipated capital investment expenses for scheme-1 and scheme-2, comprising plant fixed capital investment (FCI), start-up, working capital, and interest, are expected to be €22.1 M and €17.5 M, respectively. The equipment costs are based on first quarter of 2021 and the economic life of the project is 20 years. Monte Carlo sensitivity analyses showed that the bio-oil MFSP is most vulnerable to discounted cash flow, income tax and bio-oil yield. The production cost of bio-oil varies between €2.16/GGE and €6.19/GGE for scheme-1 and €1.78/GGE and €5.01/GGE for scheme-2 when cost parameters are varied within an industrially relevant range. The findings support the viability of producing bio-oil by catalytic fast pyrolysis on a commercial scale.
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... Typical particles size of biomass ranges from 2-3 mm in a circulating fluidized bed reactor [26,28]. The bio-oil yield ranges from 28 wt.% to 64 wt.% of dry biomass [1,28,29]. Optimum temperature for maximum bio-oil yield can vary from 400 to 520°C depending upon the type of biomass [1,[26][27][28][30][31][32]. For fluidizing purpose, nitrogen gas or non-condensable gases can be used [28,31]. ...
... The bio-oil yield ranges from 28 wt.% to 64 wt.% of dry biomass [1,28,29]. Optimum temperature for maximum bio-oil yield can vary from 400 to 520°C depending upon the type of biomass [1,[26][27][28][30][31][32]. For fluidizing purpose, nitrogen gas or non-condensable gases can be used [28,31]. ...
... Bio-oil is a mixture of a number of compounds. The compounds with significant contribution for red mud are given in the following table [1]. ...
Oil mill sewage sludge (OMWS) is a major environmental problem for olive oil producing countries. Various OMWS elimination strategies have been proposed, in particular rapid pyrolysis which is considered a promising technique and whose main product is bio-oil which finds its application as green diesel in internal combustion engines.In rapid pyrolysis, bio-oil vapors are cooled using a compression refrigeration machine. The objective of the thesis is to integrate an absorption refrigeration machine by recovering the heat of the process, replacing the compression refrigeration machine and thus reducing electricity consumption.It turns out that the sorption refrigeration process allows for better energy efficiency. The ratio of bio-oil exergy to electrical exergy goes from 27 to 102 from the conventional system to the sorption system.An economic analysis is performed to determine the minimum selling price of bio-oil as fuel (MFSP). It is observed that the MFSP is reduced from 3.63 € / GGE to 2.99 € / GGE between the conventional system and the sorption system. The difference comes from the electricity consumption avoided. The economic sensitivity analysis shows that the production cost of bio oil decreases more rapidly than the increase in the investment cost induced by this increase in production.
... 20% of biochar is mixed with OMWWS to make it less sticky and feed it into the pyrolysis reactor smoothly. Table 1 summarizes properties of OMWWS [7]. The pre-treated biomass is converted into bio-oil vapors, biochar and non-condensable gases (NCG) in the pyrolysis reactor. ...
... The pyrolysis reactor was modelled based on the kinetic parameters measured from experimental results of Agblevor et. al. [7]. Biochar is separated from the mixture of gas and vapors by high energy efficiency cyclones and subsequently fed into a combustor. ...
... It should be noted that there is no distinction between fuel yields from the two process schemes, as the reactor temperature for both process schemes were set to 400°C. Thus the same reactor yields were assumed for both schemes based on experimental data reported in Ref. [7]. Nevertheless, the two models differ in electric power consumption and capital cost of the system. ...
The technical and economic potential of olive mill waste water sludge through catalytic quick pyrolysis is investigated in this study. Using both experimental and published data, a comprehensive data-intensive process and cost model for a 100 wet (93 dry tonnes/day) plant capacity was developed for two schemes (scheme-1: Compression refrigeration machine; scheme-2: Absorption refrigeration machine). The capital cost for scheme-1 is estimated to be €17.9 M and for scheme-2 €14.1 M. The energy efficiencies of scheme-1 and scheme-2 were estimated to be 52.9% and 53.6% respectively with corresponding minimum fuel selling prices (MFSPs) of €3.02/GGE and €2.49/GGE. The bio-oil minimum fuel sale price is most vulnerable to bio-oil yield, discounted cash flow, and income tax, according to the sensitivity analysis. The findings affirm the economic feasibility of producing bio-oil via catalytic fast pyrolysis. © 2021, ETA-Florence Renewable Energies.
... Many studies have been conducted to find a cost effective technique for its management [2], [3]. The high moisture of this waste makes the solar greenhouse drying an economic and environmentally friendly technique to produce a sludge that can be used in industrial [4] and agricultural [5] application or even as a fuel [6]. ...
The objective of this paper is to improve the design of an even-span greenhouse by analyzing the effect of some climatic and design parameters on its performance of drying Olive Mill wastewater. A mathematical model describing the coupled heat and mass transfers inside the dryer was developed and simulated under different condition using COMSOL Multiphysics. An analysis of the dryer performance was conducted in terms of the obtained overall drying efficiency. The findings indicated that the use of a shallow and large pond dyer under hot climatic conditions can improve significantly the drying process. The dryer high and the extension added to the configuration had not achieved any enhancement to the drying efficiency, but can affect the calculations time and installation cost. The developed model was thus used as an effective tool to optimize the drying process.
... Utilization of PKS and coal bottom ash (CBA) in catalytic pyrolysis process helps to not only preserve the environment but also generate useful products: biochar, pyrolysis oil, and gas. Furthermore, coal ash could upgrade pyrolysis liquid product due to its alkali and alkali earth metal content [2], which has similarity with red mud that has been widely used as catalyst for biomass pyrolysis [3][4][5]. ...
... Biomass devolatilization process is often described by a onestep global model which proceeds as a single reaction [28] as shown in Eq. (4). ...
The catalytic and non-catalytic pyrolytic conversion kinetics of palm kernel shell (PKS) with untreated (as received) and H2SO4-treated coal bottom ash as catalyst were investigated in this study. Flynn-Wall-Ozawa (FWO) and distributed activation energy model (DAEM) isoconversional kinetic models were exploited to evaluate the kinetic parameters. The study was conducted using thermogravimetric analysis at 10, 20, 30, and 50 °C/min heating rates. The activation energy (Ea) and pre-exponential factor (A) for non-catalytic PKS decomposition for DAEM ranged from 74.39 to 217.05 kJ/mol and 4.77E+01 to 1.99E+14 s−1 at different conversions while for the untreated ash, the ranges were 103.84–402.53 kJ/mol and 7.35E+03–1.04E+29 s−1. In the decomposition with treated ash, Ea and A were 81.79–191.07 kJ/mol and 1.61E+02–1.20E+12 s−1 for 7 wt% ash and 74.41–137.35 kJ/mol and 4.91E+03–4.53E+08 s−1. Values of Ea and A obtained for FWO followed the same pattern and are in close agreement with that obtained using DAEM. The use of 10 wt% acid-treated ash reduced the activation energy compared with the non-catalytic process by about 33.05% while the untreated ash increased the activation energy. The kinetic parameters were determined satisfactorily using the first-order reaction mechanism.
... Utilization of palm kernel shell and coal bottom ash (CBA) in catalytic pyrolysis process, not only helps to preserve the environment but also generate useful products: biochar, pyrolysis oil and gas. Furthermore, coal ash could upgrade pyrolysis liquid product due to its alkali and alkali earth metal content [2], which has similarity with red mud that has been widely used as catalyst for biomass pyrolysis [3][4][5]. ...
... Biomass devolatilization process is often described by a one-step global model which proceeds as a single reaction [20] as shown in Equation (4). (4) where volatiles refers to the gas generated and k is pyrolysis rate constant of a reaction with a temperature dependence expressed by the Arrhenius equation (Equation 5). (5) where A is the pre-exponential factor (min -1 ), Ea is the activation energy (kJ.mol -1 ), R is the gas constant (8.314 ...
The catalytic and non-catalytic pyrolytic conversion kinetics of palm kernel shell with untreated (as received) and H 2 SO 4 treated coal bottom ash as catalyst were investigated in this study. The activation energy was determined using Flynn-Wall-Ozawa (FWO) kinetic model and distributed activation energy model (DEAM) isoconversional kinetic models. The study was conducted using thermogravimetric analysis at 10, 20, 30 and 50 °C/min heating rates. The activation energy (E a ) ranged from 145.7-228.3 kJ/mol and 142.1-274.2 kJ/mol for FWO and DEAM, respectively. The use of acid treated ash reduced the activation energy compared to the non-catalytic process while the untreated ash increased the activation energy.
... The XRD analyses of the raw red mud (fresh) and calcined FRM catalysts before and after pyrolysis show that the major changes occurred in each stage of the treatment. After calcination, the FRM lost some peaks that were attributed to gibbsite (Al(OH) 3 ) and goethite (FeO(OH)) due to dehydration of these components as reported by Agblevor et al. 88 After pyrolysis, there were major changes in the structure of the catalyst due to the conversion of almost all the hematite component to magnetite (see Supporting Information, Figure S1). Even though biochar and coke were on the surface of the used catalyst, there was no significant difference in the XRD spectra of the regenerated and used catalysts. ...
Biomass feedstocks contain inorganic compounds generally classified as ash. The ash consists of compounds of potassium, calcium, magnesium, silicon, phosphorous and other elements. These elements have been reported to influence both the pyrolysis reactions as well as destabilizing the pyrolysis oils during storage. The inorganic elements have also been reported to deposit on catalyst surfaces during in situ catalytic pyrolysis leading to the eventual deactivation of acidic catalysts such as zeolites. The deposition of inorganic elements and their effect on formulated red mud (FRM) catalyst during in situ catalytic pyrolysis of pinyon juniper wood was investigated. The inorganic elements were measured for the fresh, coked, and regenerated catalysts. The BET specific surface area of the FRM catalyst decreased from 76 m2/g for the fresh catalyst to 53 m2/g for the stable regenerated catalyst. After three regenerations, the BET specific surface area stabilized at 53 m2/g and remained constant after all other regenerations. Potassium, calcium, magnesium, and phosphorous were deposited on the catalyst. Potassium deposition was linear with the number of regenerations while magnesium and calcium depositions were initially rapid but leveled off after three regenerations of the catalyst. Phosphorous deposition was almost linear, but the data were more scattered compared to potassium. The potassium deposition was attributed to physical phenomenon whereas calcium and magnesium depositions were more akin to chemical reactions related to the loss of BET surface area of the catalyst. The deposition of these elements on the surface of the catalyst did not deactivate it. After each catalyst regeneration, the oil yield was not significantly affected and the oil oxygen content and viscosity decreased slightly. This clearly showed that formulated red mud is a robust catalyst suitable for in situ catalytic fast pyrolysis of biomass.
