Production Of Aromatic Hydrocarbons Research Articles

Hydrocarbon generation through pyrolysis of high-lipid-content microalgae within a dual-catalyst bed

The presence of oxygenated and nitrogenated compounds formed during the pyrolysis of microalgae poses challenges for utilizing bio-oil as a competitive alternative to fossil fuels. In an effort to mitigate the formation of these undesirable substances and enhance the production of aromatic hydrocarbons, this study delved into the catalytic analytical pyrolysis of Schizochytrium limacinum using a tandem catalytic bed. The research involved the characterization of Schizochytrium limacinum biomass and examining the impact of reaction temperature and the dual-catalytic bed (hydrotalcite followed by zeolite) on the formation of pyrolytic compounds and hydrocarbons. In the analytical pyrolysis, the dual-catalytic bed comprising NiHTC followed by NiHZSM-5 showed superior efficiency in deacidification and deoxygenation. Through the calcination and reduction/passivation of both catalysts, hydrocarbon production achieved noteworthy levels, reaching 89% and 92%, respectively, with a catalyst-to-biomass ratio set at 5:1. Under these optimized conditions, aromatic formation consistently remained between 60 to 70%. Furthermore, pathways were delineated to elucidate potential chemical reaction routes. The satisfactory results suggest that high-lipid content microalgae can serve as successful feedstock for hydrocarbon generation.

Towards enhanced monocyclic aromatic hydrocarbons production from Co-pyrolysis of biomass and waste polystyrene plastic

Co-pyrolysis technology offers a viable solution for utilizing biomass and waste plastics as a valuable energy resource, to support waste management, energy supply and environmental protection. In this paper, co-pyrolysis of poplar tree (PT) and polystyrene (PS) at mixture ratios of 0:1, 3:1, 2:1, 1:1, 1:2, 1:3 and 1:0 under different pyrolysis temperatures (450, 550, 650, and 700 °C), using different catalysts (HZSM-5, MCM-41, Fe/HZSM-5, and Cu/HZSM-5) were investigated using gas chromatography/mass spectrometry (Py-GC/MS) diagnostics for determining products distribution and synergistic effects. The results showed that PT performed best at a pyrolysis temperature of 650 °C, whereas PS performed best at 550 °C. The relative amount of aromatics in the co-pyrolysis products of PT and PS was highest at 550 °C that showed positive synergistic effects. The synergistic effects from the co-pyrolysis of PT and PS were significantly different at different mixture ratios of the PT and PS feedstocks. At mixture ratios of 1:1 and 1:2, the relative amounts of polycyclic aromatic hydrocarbons (PAHs) and monocyclic aromatic hydrocarbons (MAH) were higher and showed positive synergistic effects. The catalysts promoted the generation of MAH and inhibited the PAHs formation in the co-pyrolysis. The Fe/HZSM-5 catalyst provided the most significant effect on MAH showing the highest relative amounts. The results showed that highest yield of monocyclic aromatic hydrocarbons can be achieved from the pyrolysis of PT and PS materials at 1:1 mixture ratio using Fe/HZSM-5 catalyst, at a reaction temperature of 550 °C.

Role of solvent in selective hydrodeoxygenation of monomeric phenols

The current production of aromatic hydrocarbons, crucial in fuel and polymer production, relies heavily on fossil resources. Finding carbon-neutral alternatives is necessary to address the current environmental challenges. Lignin emerges as a promising source for bio-based aromatics. However, existing catalytic hydrodeoxygenation processes often yield mixtures of cycloalkanes and aromatics. In our study, we investigated a selective route to obtain aromatics from phenols using the keto-tautomer reaction mechanism. According to this mechanism, the initial hydrogenation of the carbonyl group while a phenol compound is in its keto form leads to the removal of the hydroxyl group while preserving the aromatic structure. Our experiments focused on p-cresol, guaiacol, and mequinol, employing Pd/C and Ru/C catalysts. Experimental results revealed that aromatic hydrocarbons were favored during the hydrodeoxygenation of p-cresol and mequinol, while steric effects from the methoxy group hindered guaiacol's conversion. Furthermore, we observed significantly higher conversion rates when using hydrocarbon solvents compared to water, with toluene yields of up to 13.5 % by mass achieved on Pd/C. Our computational simulations confirmed the feasibility of the keto-tautomer mechanism on Pd cluster surfaces, similar to those found in Pd/C catalysts.

Optimized production of aromatic hydrocarbons via corn stover pyrolysis: Utilizing high-density polyethylene as a hydrogen donor and red mud as a catalyst

Biomass pyrolysis offers a promising route for high-value bio-oil production, yet the process is limited by low deoxygenation efficiency. In this study, high-density polyethylene (HDPE) served as a hydrogen donor, and acid-washed red mud (ACRM) acted as a catalyst to enhance the pyrolysis of corn stover (CS) for producing monocyclic aromatic hydrocarbons (MAHs). The results showed that the addition of ACRM significantly reduced the activation energy for co-pyrolysis, enhanced the reaction rate, and strengthened the synergistic effects between CS and HDPE. Optimal conditions yielded a MAHs selectivity of 64.5 % at 650°C with a CS: HDPE ratio of 1:1. However, excessively high temperatures facilitated the cyclization and polymerization of MAHs into polycyclic aromatic hydrocarbons, while a high HDPE ratio diminished the synergistic effects. Furthermore, recycling tests confirmed the effective reusability of ACRM, with MAHs yields remaining above 40 % after four cycles. This study highlights the potential for valorizing industrial and agricultural wastes.

Synergistic Interaction during Copyrolysis of Soybean Straw and Tire Waste: Improving Emissions and Product Quality.

This study explores copyrolysis of soybean straw (SS) with hydrogen-rich tire waste (TW) to enhance pyrolytic product quality and reduce pollutant emissions. Addition of TW increased SS biomass conversion from 67.19 to 72.46% and decreased coke/residue formation from 32.81 to 27.54%. The activation energy dropped to 121.84 kJ/mol from 160.73 kJ/mol (as calculated by the Kissinger-Akahira-Sunose method) and 122.78 kJ/mol from 159.76 kJ/mol (as calculated by the Ozawa-Flynn-Wall method). Thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TG-FTIR) showed lowered CO2, NO2, and SO2 emissions (5.58, 5.72, 3.38) compared to conventional SS pyrolysis (18.38, 11.55, 12.37). Yields of value-added chemicals (phenols, olefins, aromatics) increased (32.38, 22.17, 30.18%) versus conventional SS pyrolysis (23.56, 13.78, 20.36%). Pyrolysis gas chromatography-mass spectrometry (Py/GC-MS) analysis reveals that the addition of TW leads to a decrease in the production of oxygenates and polycyclic aromatic hydrocarbons, reducing their yields to 8.96 and 7.67%, respectively, down from 19.37 and 14.37%. Simultaneously, it enhances the yields of olefins, aromatics, phenols, and aliphatic hydrocarbons to 23.38, 26.78, 26.17, and 25.78%, respectively, compared to 15.37%, 15.29, 18.36, and 17.25%, respectively, in the absence of TW. In summary, copyrolysis of TW with SS improves product quality and reduces pollutant emissions, marking a significant research contribution.

Catalytic co-pyrolysis of poplar tree and polystyrene with HZSM-5 and Fe/HZSM-5 for production of light aromatic hydrocarbons

The catalytic co-pyrolysis of biomass and plastic waste is a highly effective approach for the production of light aromatic hydrocarbons. In this study, catalytic co-pyrolysis experiments were conducted on poplar tree (PT) and polystyrene (PS) using pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS). The experiments were carried out at a temperature of 550 °C and a mixing ratio of 1:1. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques were employed for the characterization of HZSM-5 and Fe/HZSM-5 catalysts. The findings indicated that the metallic Fe in the HZSM-5 catalyst led to an enhanced production of monocyclic aromatic hydrocarbons (MAH) during the catalytic co-pyrolysis of PT and PS. The proportion of MAH in the products obtained from HZSM-5 and Fe/HZSM-5 catalyst was determined to be 85.84% and 90.87%, respectively. In the catalytic co-pyrolysis of biomass and plastic waste, several crucial reactions took place, including deoxidation, olefins aromatization, and Diels-Alder reaction between furans and olefins. In the presence of Fe metal, the HZSM-5 catalyst exhibited enhanced selectivity towards valuable MAH while effectively suppressing the formation of polycyclic aromatic hydrocarbons, resulting in an increase in MAH production to 90.87%.

Promoted production of aromatic hydrocarbons in biomass catalytic pyrolysis over the coupled catalysts of carbon-reduced waste lithium battery cathode materials and HZSM-5

Inexpensive catalyst sources are of great importance in the conversion of biomass to economically valuable monocyclic aromatic hydrocarbons, and transition metals (Co, Ni, Fe and Mn) rich in catalytic effects in massive waste lithium battery cathode materials are not effectively reutilized currently. For this reason, the feasibility of employing the valuable metal oxides in the carbon-reduced waste lithium battery cathode materials (waste LiFePO4 batteries, LFP, and waste LiNixCoyMn1–x–yO2 batteries, NCM) with HZSM-5 as coupled catalysts in the rape straw catalytic pyrolysis to produce aromatic hydrocarbons was explored. The carbon-reduced waste lithium battery cathode materials performed well at 5 wt% carbon loading, and the content of active components Fe2O3 (SLFPC-5) and NiO (SNCMC-5) used for the reduction of large molecular oxygenates in biomass pyrolysis gas was increased by water leaching treatment. SLFPC-5 demonstrated superior bond-cutting performance, while SNCMC-5 exhibited strong deoxygenation performance. The selectivity of monocyclic aromatic hydrocarbons (MAHs) catalyzed by SLFPC-5/HZSM-5 and SNCMC-5/HZSM-5 was as high as 63.69 % and 79.19 %, with BTX yields of 14.58 wt% and 16.68 wt% respectively. This coupled catalytic system offers a low-cost source of catalysts for biomass catalytic pyrolysis and broadens the possibility of high-value recycling of wasted lithium batteries.

One-pot synthesis of Fe modified lignin biochar for ex-situ catalytic fast pyrolysis of enzymatic hydrolysis lignin to promote the generation of aromatic hydrocarbons

The utilization of waste lignin to produce bio-oil rich in aromatics aromatic hydrocarbons is promising and attractive for a wide range of applications. Fe-modified lignin biochar (xFe/ALC) prepared using a one-step method was utilized as catalysts to investigate their impact on product distribution, aromatic hydrocarbon generation, and pathways during ex-situ catalytic fast pyrolysis of enzymatic hydrolysis lignin. The results revealed that the addition of Fe enhanced the production of gas products such as H2, while decreasing bio-oil yield. The lowest bio-oil yield, at 12.10 wt%, was observed at a Fe loading of 25 wt%, however the relative content of aromatic hydrocarbons reached a maximum value of 16.24 area%. Compared to the pyrolysis of lignin alone, their contents increased by 2.46 times, with the content of monocyclic aromatic hydrocarbons (toluene, ethylbenzene, styrene, xylene) increasing by 1.5–3.8 times. Spent 25Fe/ALC had good stability on the production of aromatic hydrocarbons. Compared with non-catalytic pyrolysis of lignin, the aromatic hydrocarbons content for spent 25Fe/ALC after four cycles increased by 26.70%.

Production of monocyclic aromatic hydrocarbons by the catalytic pyrolysis of Moso bamboo at different ages and parts using Zn and Cr modified zeolite catalysts

Monocyclic aromatic hydrocarbons (MAHs) are important organic building blocks for the chemical industry, which can be produced by catalytic pyrolysis of biomass. The wide application of bamboo in Chinese industry generates a large amount of bamboo waste which can be utilized as the feedstock to produce MAHs. This study aimed to investigate the effect of bamboo age and bamboo part on the yield of the aromatics by using the Cr and Zn modified HZSM-5 as catalyst. The result showed that the incorporation of metals (Cr and Zn) enhanced the catalytic performance, and the incorporation of Zn was better than Cr. The highest MAHs content (38.67%) and total aromatic content (57.42%) were obtained with the catalyst of 3% Zn/HZSM-5 catalyst at temperature of 400 °C and duration time of 30 min. Younger age (1-year-old bamboo) and the outer skin of bamboo was better for the production of MAHs. This study provided a high value-added application approach for the waste Moso bamboo.

Production of Aromatic Hydrocarbons from Co-Hydropyrolysis of Biomass Components and HDPE with Application of Modified HZSM-5 Catalyst.

Experiments were conducted in this study on the co-hydropyrolysis of three components of biomass (cellulose, hemicellulose, and lignin) and HDPE by using SR-Pd/Trap-HZ-5 as catalyst. To control the variable, we use the same experiment conditions in co-hydropyrolysis: Si/Al ratio of 50, Pd load 1 %, catalyst to reactant ratio of 1 : 10, 1 MPa, 400 °C, reaction time 1 h. Use XRD, TEM, BET, and NH3-TPD to confirm catalyst successful synthesis; use pine sawdust (PW) co-hydropyrolysis with HDPE to analyse catalytic activity; and use GC/MS to characterize the chemical composition of the bio-oil from the co-hydropyrolysis of biomass components and HDPE. The results show that cellulose has a significant synergistic effect with aromatic hydrocarbon production, whose selectivity was 93.3 %; hemicellulose has a synergistic effect; aromatic selectivity can reach 75.1 %; and a negative synergistic effect between lignin and HDPE was shown as the selectivity of aromatic hydrocarbons decreased from 62.1 % to 15.6 %.

Co-pyrolysis of vineyards biomass waste and plastic waste: Thermal behavior, pyrolytic characteristic, kinetics, and thermodynamics analysis

Biomass and waste plastic (WP) co-pyrolysis can reduce the oxygen content of pyrolysis oil and improve its quality. However, the current understanding of the interaction mechanisms during the co-pyrolysis process remains unclear and incomplete, hindering its further development. In this study, the thermal behaviors and pyrolytic characteristics of biomass co-pyrolysis with WP were investigated using TG-FTIR and Py-GC/MS, and kinetics and thermodynamics were further explored. The results indicated a significant interaction between biomass and WP during co-pyrolysis. The WP was softened by heat during the early stages of pyrolysis to envelop the biomass, thereby inhibiting the release of volatile components. In the later stage it showed a facilitating effect, where, free radicals generated from the biomass initiate the destruction of the WP polymer chains releasing hydrogen radicals. In turn, the hydrogen radicals act on the pyrolysis of the biomass to promote the production of aromatic hydrocarbons. The kinetics and thermodynamics analysis also revealed that co-pyrolysis reduces the activation energy and Gibbs free energy. This study promotes the synergistic disposal of two solid wastes and has the significance of realizing the green and efficient preparation of high-quality pyrolysis oil.

Single and Combined Effects of Phenanthrene and Silver Nanoparticles on Denitrification Processes in Coastal Marine Sediments.

The increasing production and utilization of polycyclic aromatic hydrocarbons (PAHs) and commercial silver nanoparticles (AgNPs) have raised concerns about their potential environmental release, with coastal sediments as a substantial sink. To better understanding the effects of these contaminants on denitrification processes in coastal marine sediments, a short-term exposure simulation experiment was conducted. We investigated the effects of single and combined contamination of phenanthrene (Phe) and AgNPs on denitrification processes in a coastal marine sediment. Results showed that all contaminated treatment groups had different degrees of inhibitory effect on denitrification activity, denitrifying enzyme activity, total bacteria count and denitrifying genes. The inhibitory effect sequence of each treatment group was combined treatment > AgNPs treatment > Phe treatment. Moreover, the inhibitory effects of denitrifying genes were much larger than that of total bacteria count, indicating that the pollutants had specific toxic effects on denitrifying bacteria. The sequence of sensitivity of three reduction process to pollutants was N2O > NO2- > NO3-. All contaminated treatment groups could increase NO3-, NO2- and N2O accumulation. Furthermore, according to the linear relationship between functional gene or reductase and denitrification process, we also found that the abundance of denitrifying genes could better predict the influence of Phe and AgNPs on sediment denitrification than the denitrifying bacterial diversity. In addition, at the genus level, the community structure of nirS- and nosZ-type denitrifying bacteria changed dramatically, while changes at the phylum level were comparatively less pronounced. Single and combined contamination of Phe and AgNPs could reduce the dominance of Pseudomonas, which may lead to a potential slow-down in the degradation of Phe and inhibition of denitrification, especially the combined contamination. Overall, our study revealed that combined contamination of Phe and AgNPs could lead to an increase in NO3-, NO2- and N2O accumulation in coastal sediment, which poses a risk of eutrophication in coastal areas, exacerbates the greenhouse effect and has adverse effects on global climate change.

Review on the progress in the production of aromatic hydrocarbons by co-catalytic pyrolysis of biomass and plastics

Review on the progress in the production of aromatic hydrocarbons by co-catalytic pyrolysis of biomass and plastics

Production of monocyclic aromatic hydrocarbons from microwave co-pyrolysis of polyethylene terephthalate and low-density polyethylene using coconut husk carbon as microwave absorbent

The application of biochar as microwave absorbers in microwave-assisted catalytic fast pyrolysis (MACFP) has been widely studied. It has been reported that coconut husk carbon (CHC) showed good process characteristics and product distribution as microwave absorbers. However, the existing studies did not pay much attention to the reusability of CHC absorbers. In this study, the CHC absorbers prepared from agricultural and forestry wastes were reused in multiple cycles in the MACFP of polyethylene terephthalate (PET) and low-density polyethylene (LDPE). Compared with typical microwave absorbers such as spherical silicon carbide (SiC) and granular activated carbon (GAC), CHC demonstrated favorable process characteristics with relatively high heating rate (29 °C/min) and short heating time (within 12 min). In terms of product properties, the highest liquid yield of 51.67 wt% and the highest content of monocyclic aromatic hydrocarbons (MAHs) of 82.82 % were obtained at the appropriate pyrolysis temperature (550 °C). After five consecutive uses, the CHC bed still produced comparable heating profiles and product distributions, compared to that of SiC. At the same time, a positive synergistic effect between PET and LDPE was observed. The co-feeding of PET and LDPE (50L50P) appropriately increased the liquid yield (42.50 wt% vs 38.75 wt%) and the relative content of MAHs (77.11 % vs 72.96 %) in comparison to their theoretical value. Finally, this study supplies a new strategy for utilizing recycled CHC as a microwave absorber for the treatment of hydrogen-rich and hydrogen-deficient mixed plastic wastes to produce MAHs products, which also reduces waste and realizes energy conversion.

Thermal degradation of emerging pollutants in municipal solid wastes and agro wastes: effectiveness of catalysts and pretreatment for the conversion of value added products

In this study, emerging soil pollutants in the form of municipal solid waste (MSW) and agricultural waste were converted into biofuel via thermal degradation process. Among various waste-to-energy conversion processes, the pyrolysis of biomass is considered the most significant due to its maximum biofuel yield than other conversion techniques. Individual and co-pyrolysis of MSW and sugarcane residue (SR) as well as its treated variant (TSR) were performed in a lab-setup fixed-bed reactor with and without catalyst. The effect of acid pretreatment and catalytic effects on the pyrolysis process was assessed in terms of product yields and characterization. The acidic pretreatment of SR and catalyst in the pyrolysis process alters the process yield and its composition. The maximum oil yield of 50.5 wt% was achieved by catalytic co-pyrolysis of MSW + TSR + HZSM5, whereas the maximum gas yield of 38.1 wt% was achieved by catalytic co-pyrolysis of MSW + SR + HZSM5. This suggests that intrinsic minerals present in the biomass and MSW, particularly alkali and alkaline earth metals, have a catalytic effect on the devolatilization of organic material and the char cracking event. The pretreatment of biomass showed considerable improvement in the properties of the produced pyrolysis oil and char. Compared to the pyrolysis oil and char obtained from MSW + SR, the oil and char obtained from MSW + TSR + HZSM5 showed a small increment in their heating values. Pretreatment and the catalytic co-pyrolysis process influenced the structure of the pyrolysis oils, increasing the production of phenolic compounds and aromatic hydrocarbons. The amount of gas components in pyrolysis gas, such as CH4, CO2, and CO also changed more according to the feedstock used for the process. Overall, the HZSM-5 catalyst and co-pyrolysis of MSW with pretreated SR enhanced the pyrolysis conversion of waste municipal solids and agricultural wastes into energy-rich products.

Catalytic pyrolysis of rape straw to produce light aromatic hydrocarbons over HZSM-5 loaded by metal ions from spent lithium batteries extracted with citric acid

In this study, metal-loaded HZSM-5 was prepared with metal ion extracted from the cathode materials of spent lithium batteries (lithium iron phosphate, LFP; lithium nickel-cobalt manganate, NCM) with citric acid for the improved production of light aromatic hydrocarbons by catalytic pyrolysis of rape straw. Because of the dealuminization effect of citric acid on HZSM-5, mesopores were introduced, and the diffusion and conversion of pyrolysis gas over acid sites were improved. After metal loading with acid-leaching solution, the amount of weak and total acids in metal-loaded HZSM-5 increased a lot, which was conducive to the dehydration, deoxygenation, decarbonylation and aromatization of pyrolysis, and the production of monocyclic aromatic hydrocarbons (MAHs). With 0.1 mol/L citric acid for LFP and NCM treatment, the metal-loaded catalyst showed a higher yield of benzene, toluene and xylene (BTX) of 11.10 wt% during catalytic pyrolysis of rape straw. Compared with 0.1-NCM-H5, a higher yield of MAHs was obtained over 0.1-LFP-H5 with a more favorable pore structure and higher amounts of weak and total acid sites. In general, the high-valued utilization of agricultural wastes and spent lithium batteries was realized in this study to produce clean energy.

Coupling of Steam and CaO Derived from Oyster Shells in the Pyrolysis of Waste Poly(ethylene terephthalate) for the Selective Production of Aromatic Hydrocarbons

Coupling of Steam and CaO Derived from Oyster Shells in the Pyrolysis of Waste Poly(ethylene terephthalate) for the Selective Production of Aromatic Hydrocarbons

Aromatic bio-oil production from corn stover by FAU + MFI dual-catalyst catalytic fast pyrolysis: A study of two catalyst parameters

The dual-catalyst catalytic fast pyrolysis (CFP) is a promising approach for producing hydrocarbon-rich bio-oil from biomass waste. However, the lack of detailed research on the structural parameters of the first- and second-layered catalysts was lacking and hindered the development of this technology. Herein, dual-catalyst CFP of corn stover was conducted, and the effects of the acidity and porosity of the two-layered catalysts were studied in detail to enhance their synergistic effect. The results demonstrated that for the second-layered catalyst (MFI zeolite), the utilization of a strong acidic ZSM-5(25) facilitated the production of aromatic hydrocarbon (38.8 area%). For the first-layered catalyst (FAU zeolite), the employment of medium acidity and microporous HY(2.6) was advantageous for the production of valuable monocyclic aromatic hydrocarbon (MAHs) with a selectivity of 21.5 area%, which was ∼1.6 times higher than that in the less acidic HX(1.5) + ZSM-5(25) trial. These findings confirmed that the synergy between the two-layered catalysts was dramatically enhanced by using the HY(2.6) + ZSM-5(25) catalyst combination. Finally, a proposed reaction pathway for the dual-catalyst CFP of corn stover was provided to guide the optimization of dual-catalyst CFP technology and the design of pyrolysis catalyst.

Превращение комбинированного сырья на цеолитсодержащих катализаторах

The article discusses the ways of rational use of hydrocarbon raw materials in order to obtain isoparaffin and aromatic hydrocarbons. The possibilities of joint processing of the 75-100°C fraction have been studied from gas condensate and propane-butane fraction (PBF) in an anhydrous environment and in the presence of a modified zeolite-containing catalyst. The regularities of the yield of aromatic and isoparaffinic hydrocarbons of the anhydrous process of catalytic conversion of combined hydrocarbon raw materials on a zeolite-containing Pt/Beta catalyst modified by 0.5% wt have been established platinum. So, when converting a fraction of 75-100°C. With a temperature range of 300-350°C, the content of isoparaffins in liquid products increases by more than 20% by weight. A further increase in temperature is accompanied to a greater extent by the formation of aromatic hydrocarbons. The total content of benzene, toluene, xylenes is about 20% by weight. Similar trends are observed when testing the propane-butane fraction. The greatest increase in isoparaffin hydrocarbons is also observed at a temperature of 300°C. Their content in liquid and gaseous products increases by an average of 10%. The main share in this process is accounted for by iso-butane. Accordingly, an increase in the reaction temperature by 100°C increases the formation of benzene and toluene by 11% by weight. More significant results were obtained during the joint transformation of the 75-100°C fraction and the propane-butane fraction. At a reaction temperature of 300°C, a high content of iso-butane is observed in gaseous products, which allows them to be involved in petrochemical processes. The content of isoparaffins in liquid products increases by 50% by weight, which makes them valuable as a high-octane component of motor fuels. Favorable temperatures for the production of aromatic hydrocarbons are 400°C and above.

Monocyclic aromatic hydrocarbons production from NaOH pretreatment metallized food plastic packaging waste through microwave pyrolysis coupled with ex-situ catalytic reforming

Metallized food plastic packaging waste (MFPPW), as found in packaging bags like potato chips and coffee, presents an intricate structural and compositional complexity, rendering its recycling considerably more challenging in comparison to pure plastic packaging. In this work, a process route to produce monocyclic aromatic hydrocarbons (MAHs) from caustic (NaOH) treatment MFPPW through microwave pyrolysis coupled with ex-situ catalytic reforming was proposed. NaOH pretreatment disrupted the chemical bonds between the plastic layers and aluminum layer, reducing the complexity of the subsequent pyrolysis reaction. The removal of the aluminum layer diminished its shielding effect on the microwave, and enhanced the efficient conversion of the microwave energy into heat energy, thus accelerating the pyrolysis of the remaining plastic. After pretreatment, the activation energy for the pyrolysis reaction decreased from 250.55 kJ/mol to 189.70 kJ/mol, and the MAHs content of the liquid oil increased. The highest MAHs content of 80.50% was achieved with an HZSM-5 (Si/Al = 50) zeolite catalyst, pyrolysis temperature of 550°C, and catalysis temperature of 550°C. The unique characteristics of the MFPPW demonstrate its suitability for MAHs production. MFPPW is predominantly composed of PP and PET polymers. PP, as a hydrogen-rich plastic, provides abundant hydrogen-rich free radicals to the PET and promotes hydrogen transfer reactions, thus facilitating the formation of MAHs. Following pretreatment, these two polymers come into closer contact, further enhancing their synergy. This study provides valuable insight into waste management and recovery for metallized food plastic packaging waste.