Production Of Aromatic Hydrocarbons Research Articles

Aromatic hydrocarbon selectivity as a function of CaO basicity and aging during CaO-catalyzed PET pyrolysis using tandem µ-reactor-GC/MS

During the tandem pyrolysis of poly(ethylene terephthalate) (PET) and catalytic conversion of the PET pyrolysates over calcium oxide (PET/CaO process), the relationship between catalyst deterioration and the aromatic hydrocarbon selectivity was elucidated. Using a tandem micro (µ)-reactor-gas chromatography/mass spectrometry (TR-GC/MS) system, PET was pyrolyzed at 450°C in the 1st µ-reactor and the PET pyrolysates were refined over one of two CaO catalysts with different basicities at 700°C in the 2nd µ-reactor. Strongly basic CaO enhanced benzene production via decarboxylation, resulting in 83.6% selectivity for aromatic hydrocarbon products. This selectivity decreased with repeated runs over the strongly basic CaO, while oxygen-containing compounds such as benzophenone and benzoic acid increased. The surface morphology changes observed by scanning electron microscopy indicated that CaO was thoroughly sintered with repeated use, which reduced its basicity. The less-basic CaO effected diminished carboxyl-unit surface adsorption and suffered deteriorated deoxygenation ability. Thus, this study clearly demonstrates that CaO deterioration (by sintering during repeated PET/CaO processing) and CaO basicity strongly influence reaction selectivity.

In-situ catalytic co-pyrolysis of yellow poplar and high-density polyethylene over mesoporous catalysts

Catalytic co-pyrolysis of biomass and hydrogen-rich materials is an effective approach for enhancing the production of bio-based hydrocarbons. In this work, mesoporous solid acid materials, such as hierarchical mesoporous MFI (meso MFI), hierarchical mesoporous Y (meso Y) and Al-SBA-15, were used as the catalysts for the catalytic co-pyrolysis of yellow poplar (YP) and high-density polyethylene (HDPE). Among three catalysts, meso MFI revealed the highest catalytic efficiency for the production of aromatic hydrocarbons from catalytic pyrolysis of YP or HDPE due to its effective pore structure, large channels, and high acidity. Moreover, meso MFI showed the highest synergistic formation of aromatic hydrocarbons during the catalytic co-pyrolysis of YP and HDPE as a result of hydrogen donating effect of HDPE and catalytic interactions between YP- and HDPE-derived pyrolyzates. The amounts of solid residue obtained from the catalytic co-pyrolysis of YP and HDPE over meso MFI were also much lower than their theoretical yields.

Catalytic conversion of guaiacol as a model compound for aromatic hydrocarbon production

Guaiacol, a mono-aromatic compound containing a hydroxyl and a methoxyl group, is one of the main products from lignin pyrolysis. In order to investigate the feasibility of aromatic hydrocarbons production from lignin, guaiacol was employed as the model compound for the catalytic conversion over HZSM-5 zeolites with different Si/Al ratios in a fixed-bed reactor under the temperatures from 500 °C to 800 °C. With the increased temperature, the yield of both aromatic hydrocarbons (such as benzene, toluene, styrene, naphthalene and 2-methylnaphtalene) and coke was increased from the mass fraction of 1.83%–24.27% and from 1.17% to 12.81%, respectively. At 600 °C, the yield of benzene was promoted by the HZSM-5 catalyst with high Si/Al ratio (200) by the mass fraction of 2.94% and up to 1.94% for that of toluene. The production of monocyclic aromatic hydrocarbons (especially for benzene and p-xylene) was favored with the loading of Ni on HZSM-5(25), while the formation of polycyclic aromatic hydrocarbons was notably inhabited. The coke deposition was slightly increased with the increased loading of Ni during the catalytic conversion of guaiacol. The demethoxylation and dehydroxylation reactions were considered to be promoted by the increase of Brønsted acid sites, while the methyl substitution reaction was slightly influenced by the total acidity of catalyst. The experimental results provided the conceptual and technical support for the catalytic pyrolysis of lignin to produce aromatic hydrocarbons.

Direct deoxygenation of lignin model compounds into aromatic hydrocarbons through hydrogen transfer reaction

A new route is reported for the direct deoxygenation of lignin model compounds to aromatic hydrocarbons via the catalytic hydrogen transfer reactions over Ru/Nb2O5-SiO2 catalyst with 2-PrOH as a hydrogen donor. It is found that Ru/Nb2O5-SiO2 catalyst is active for the hydrodeoxygenation of p-cresol with 98.5% conversion and 84.0% yield of toluene at 230°C, owing to the significant promotion effect of NbOx species on CO bond cleavage and the proper transfer hydrogenation activity of Ru. Furthermore, Ru/Nb2O5-SiO2 catalyst also shows excellent performances in the transfer hydrodeoxygenation of various lignin model compounds such as 2-methoxy-4-methyl phenol, benzyl phenyl ether (α-O-4 model compound), 2-(2-methoxyphenyl)oxy-1-phenethanol (β-O-4 model compound) and even the real lignin extracted from birch, into aromatic hydrocarbons with 2-PrOH as the hydrogen donor. The reaction pathway studies of these model compounds demonstrate that the direct deoxygenation (DDO) is the main reaction route over Ru/Nb2O5-SiO2 catalyst in the presence of 2-PrOH. Here, using 2-PrOH as a hydrogen source is found to be more selective to aromatic hydrocarbons than using molecular hydrogen. This work provides a new way for the high selective production of aromatic hydrocarbons from renewable lignin via the catalytic hydrogen transfer reactions.

Parametric study of two-stage hydropyrolysis of lignocellulosic biomass for production of gaseous and light aromatic hydrocarbons

Non-catalytic hydropyrolysis of pinewood and its components was carried out using a two-stage reactor. The main aim of this work is to investigate the hydrodeoxygenation and hydrogenation of volatile matter in the post hydrocracking reactor for oriented production of gaseous and light aromatic hydrocarbons. A portion of volatile matter, which evolved from hemicellulose, neutral extractives and lignin below 275°C, was found to be thoroughly hydrodeoxygenated preventing the release of CO2 and CO. Increasing hydrocracking temperature from 600°C to 750°C and pressure from 1.0MPa to 5.0MPa strongly facilitated the hydrogenation reactions to target products. The summed yield of CH4 and C2H6 (dry biomass basis) reached up to 33.2% at a hydrocracking temperature of 750°C and 5.0MPa, with a concomitant 5.1% yield of BTX. All components in pinewood significantly contributed to the production of CH4 and BTX by hydropyrolysis, differing from the case of pyrolysis.

Catalytic co-pyrolysis of biomass carbohydrates with LLDPE over Al-SBA-15 and mesoporous ZSM-5

The catalytic co-pyrolysis of biomass carbohydrates and LLDPE over mesoporous catalysts, mesoporous ZSM-5 (MZSM-5) and Al-SBA-15, was investigated using a tandem micro reactor-GC/MS system. The properties of the synthesized MZSM-5 and Al-SBA-15 were characterized by N2-sorption, X-ray diffraction, and NH3-temperature programmed desorption. Compared to Al-SBA-15, MZSM-5 showed better performance in the production of aromatic hydrocarbons during the catalytic pyrolysis of carbohydrates (avicel (cellulose) and xylan) due to the stronger acidity of MZSM-5. The catalytic co-pyrolysis of carbohydrates and LLDPE showed synergistic aromatic formation due to the supply of more effective hydrocarbon pool species and an efficient Diels-Alder reaction between the pyrolyzates of the carbohydrates and LLDPE. When avicel was torrefied, the aromatic yields were increased further in catalytic pyrolysis/co-pyrolysis.

Emerging contaminants related to the occurrence of forest fires in the Spanish Mediterranean

Forest fires can be a source of contamination because, among others, of the use of chemicals to their extinction (flame retardants, FRs), or by the production of Polycyclic Aromatic Hydrocarbons (PAHs) derived from high temperature alteration of organic matter. Up to our knowledge, this study is the first to assess the direct (PAHs 16 on the USA EPA's priority list), and indirect [tri- to hepta- brominated diphenyl ethers (PBDEs), organophosphorus flame retardants (PFRs) and perfluoroalkyl substances (PFASs)] contamination related to forest fires. The abundance and distribution of these contaminants were monitored on two Mediterranean hillslopes, one burned and one unburned, near Azuébar (SE Spain). Samples were taken in the foot, middle, and top of the slope, at two depths, and in two environments (under canopy and bare soil). Sediments were collected from sediment fences after erosive rainfall events. Most of the screened compounds were found in both, burned and control hillslopes, though significant differences were found between both. In burned soil, low concentrations of PBDEs (maximum ΣPBDEs: 7.3ngg−1), PFRs (664.4ngg−1) and PFASs (56.4ngg−1) were detected in relation to PAHs (Σ16 PAHs=1255.3ngg−1). No significant influence of the hillslope position was observed for any of the contaminants but differences based on depth and vegetation presence tended to be significant, particularly for the PAHs. After the first erosive event, concentrations of PBDEs and PAHs were higher in sediment than in soil (ΣPBDEs: 17.8ngg−1 and Σ16 PAHs=3154.2ngg−1) pointing out the importance of connectivity processes, especially shortly after fire.

Study on aromatics production via the catalytic pyrolysis vapor upgrading of biomass using metal-loaded modified H-ZSM-5

The main objective of this work was to study aromatics production via the catalytic pyrolysis upgrading of biomass using metal-loaded modified H-ZSM-5. M-ZSM-5 catalysts were prepared through the impregnation method with Zn, Ga, Ni, Co, Mg and Cu. The prepared M-ZSM-5 catalysts were evaluated by x-ray diffraction, thermal desorption spectroscopy and scanning electron microscopy. The properties, composition and product distribution of bio-oil were also analysed. Results showed that the M-ZSM-5 catalysts yielded a higher amount of non-condensable gas at the expense of the liquid yields. The Ga-ZSM-5 catalysts produced the highest yields of bio-oil (25.76wt%), but the lowest amount of coke (22.08wt%) compared with the unmodified ZSM-5 catalyst (33.38wt%). The content of the single-ring aromatics prepared by using the Zn-ZSM-5 catalysts was the highest at 90.28wt%, whereas that of the polycyclic aromatic hydrocarbon prepared by the Ni-ZSM-5 catalysts was the highest at 31.36wt%. Moreover, the selectivity of the single-ring aromatic hydrocarbons, such as C7 and C8, were significantly affected by the use of the M-ZSM-5 catalysts. The Zn-ZSM-5 catalysts were the most selective for toluene and xylenes with contents of 36.52wt% and 35.32wt%, respectively, whereas the Co-based catalysts were the most selective for indene. The Ni-based catalysts can obviously improve the selectivities of benzene production and C10+ polycyclic aromatic hydrocarbons. Zn-ZSM-5 was the most effective catalyst that can be used in the production of aromatic hydrocarbons.

Catalytic Stepwise Pyrolysis of Technical Lignin

The stepwise pyrolysis of technical lignin with and without a catalyst was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Lignin was first pyrolyzed at 260 or 360 °C, and then the residue was subsequently pyrolyzed at 650 °C. It was found that stepwise pyrolysis of lignin concentrated the phenolic compounds in lignin-derived bio-oil. In a stepwise 260 to 650 °C process, the maximum total phenolic compounds were 86.2%. Among the phenolic compounds, guaiacol-type and phenol-type phenolic compounds were predominant. Further addition of a catalyst (HZSM-5) in the stepwise pyrolysis process enhanced control over the product distribution through conversion of phenolic compounds into aromatic hydrocarbon products. The aromatic hydrocarbons achieved the highest yield of 30.4% in the catalytic stepwise 260 to 650 °C process.

Production of aromatic hydrocarbons from catalytic pyrolysis of lignin over acid-activated bentonite clay

Natural bentonite clay (mainly sodium-rich montmorillonite) both purified and acid activated using HCl, H2SO4, and H3PO4 acids were applied to the catalytic fast pyrolysis (CFP) of lignin. The modifications in crystalline structure and acidity of the activated clay were investigated via XRD, N2-adsorption-desorption, FTIR, TGA and NH3-TPD analysis. The activity and selectivity of the clays were evaluated for lignin conversion in down- flow micro reactor in the temperature range 500–650°0C in flowing Nitrogen (oxygen-free). The yields of high value added monocyclic aromatics such as BTX (benzene- toluene- xylenes) and naphthalene were increased by catalytic upgrading using HCl-activated bentonite clay. The selectivity for o&p-xylenes, naphthalene, and methyl naphthalene were greatly enhanced using HCl-activated bentonite in the temperature range 550–650°C. The catalyst: lignin ratio 3:1 and the nitrogen flow rate 75ml/min, at 600°C were the optimum conditions.

Catalytic co-pyrolysis of torrefied yellow poplar and high-density polyethylene using microporous HZSM-5 and mesoporous Al-MCM-41 catalysts

The catalytic pyrolysis of lignocellulosic biomass with aluminosilicate catalysts is a promising method for the direct production of liquid hydrocarbon fuels consisting mainly of aromatic compounds (e.g., benzene, toluene, and xylenes). On the other hand, the economic and commercial viability of this process is limited by the low yields of aromatic hydrocarbons. In this study, the effects of biomass torrefaction, co-feeding of plastic wastes, their combination, and the catalytic upgrading mode (in-situ vs ex-situ) on the aromatic formation efficiency during the catalytic pyrolysis of yellow poplar were evaluated systematically to maximize the production of aromatic hydrocarbons. Two representative catalysts for catalytic pyrolysis (i.e., microporous HZSM-5 and mesoporous Al-MCM-41) were used in this case study. The torrefaction of yellow poplar led to the enhanced production of aromatic hydrocarbons in the catalytic co-pyrolysis of yellow poplar and high-density polyethylene over both catalysts. The experimental yields of aromatic hydrocarbons from the catalytic co-pyrolysis of torrefied yellow poplar and high-density polyethylene were also higher than their theoretical yields, highlighting the synergistic aromatic formation by the interaction of torrefied yellow poplar and high-density polyethylene. Between the two catalysts, microporous HZSM-5 exhibited much higher activity for aromatic production from catalytic co-pyrolysis owing to its strong acidity and appropriate pore structure. Compared to ex-situ catalytic co-pyrolysis, the in-situ catalytic co-pyrolysis of torrefied yellow poplar and high-density polyethylene produced larger amounts of aromatic hydrocarbons due to the more effective contact between the pyrolysis vapors and HZSM-5.

Effects of alkali-treated hierarchical HZSM-5 zeolites on the production of aromatic hydrocarbons from catalytic fast pyrolysis of waste cardboard

The effects of hierarchical porous HZSM-5 zeolites on improving the yield of aromatic hydrocarbons during catalytic fast pyrolysis (CFP) of waste cardboard (WCB) were investigated. Desilicated HZSM-5 zeolites were successfully prepared by alkaline treatment using NaOH solution with different concentrations (0.1M–0.7M). A Py-GC/MS apparatus was adopted to carry out the CFP experiments. Results showed that under mild alkaline treatment (NaOH concentration ≤0.3M), the micropores and crystallinity of HZSM-5 were preserved, while the mesopores and weak acid sites increased. The desilicated HZSM-5 zeolites increased the total yield of pyrolytic products from WCB. With regard to the product distribution, carbon yield of aromatics increased dramatically, while that of sugars, carbonyl compounds and other oxygenates decreased obviously. Specifically, HZSM-5 treated by 0.3M NaOH solution (HZ-0.3M) was proved to be the most effective catalyst, resulting in a 44% increase of carbon yield of aromatics and an 82% increase of carbon yield of BTX (benzene, toluene and xylenes) comparing to the parent HZSM-5. In addition, the amount of coke deposited on HZ-0.3M decreased by 29% compared to that on the parent HZSM-5. The retained micropores and the created mesopores of desilicated HZSM-5 zeolites contributed to the enhancement of catalytic performance. However, harsh alkaline treatment of HZSM-5 zeolites (NaOH concentration ≥0.5M) resulted in the grave collapse of zeolitic crystallinity and the obvious loss of micropores. As a result, the catalytic activities of HZSM-5 zeolites had been weakened.

Mystery of 1-Vinylpropargyl Formation from Acetylene Addition to the Propargyl Radical: An Open-and-Shut Case.

The addition of acetylene (C2H2) to the propargyl radical (C3H3) initiates a cascade of molecular weight growth reactions that result in the production of polycyclic aromatic hydrocarbons (PAHs) in flames. Although it is well-established that the first reaction step produces the cyclic C5H5 radical cyclopentadienyl (c-C5H5), recent studies have also detected significant quantities of the open-chain form, 1-vinylpropargyl (l-C5H5). This work presents a mechanism for the C3H3 + C2H2 reaction from ab initio calculations, which includes pathways for the formation of both the open and shut isomers as well as for their interconversion. Formation of both isomers proceeds from the initial HCCCH2CHCH• reaction adduct with similar barriers, both well below the entrance channel energy. Subsequent isomerization of l-C5H5 with c-C5H5 also transpires at below the energy of the reactants, although this process connects two deep wells (being resonance stabilized radicals), and must compete with collisional energy transfer. An RRKM theory/master equation model is developed for the reported C5H5 reaction mechanism. Master equation simulations suggest that both cyclic and open-chain isomers are expected to form from the C3H3 + C2H2 reaction across a range of temperatures, although the lifetime of l-C5H5 is relatively short for rearrangement to c-C5H5.

Ex-situ catalytic pyrolysis of wastewater sewage sludge – A micro-pyrolysis study

Concerns over increasing amounts of sewage sludge and unsustainability of current disposal methods have led to development of alternative routes for sludge management. The large amount of organics in sewage sludge makes it potential feedstock for energy or fuel production via thermochemical pathways. In this study, ex-situ catalytic pyrolysis using HZSM-5 catalyst was explored for the production of olefinic and aromatic hydrocarbons and nutrient-rich char from sewage sludge. The optimal pyrolysis and catalysis temperatures were found to be 500°C and 600°C, respectively. Carbon yields of hydrocarbons from sewage sludge were higher than for lignocellulose; yield differences were attributed to the high extractives content in the sludge. Full recovery of most inorganic elements were found in the char, which suggests that catalyst deactivation maybe alleviated through ex-situ catalytic pyrolysis. Most of the nitrogen was retained in the char while 31.80% was released as ammonia, which suggests a potential for nitrogen recycling.

Role of Potassium Exchange in Catalytic Pyrolysis of Biomass over ZSM-5: Formation of Alkyl Phenols and Furans

Catalytic fast pyrolysis of biomass with ZSM-5 type zeolites is a commonly considered in situ upgrading technique for the production of partially deoxygenated bio-oils. The acidity and structure of ZSM-5 catalysts favor the production of aromatic hydrocarbons from oxygenates present in the pyrolysis vapors, such as acids, anhydrosugars, ketones and aldehydes. However, these acid catalyzed deoxygenation pathways remove functional groups from the aromatic ring structure, which makes the liquid bio-oil more amenable to processing in current petroleum refineries while subsequently decreasing the value of the compounds as industrial chemical feedstocks. The observation of improved yields of alkyl phenols and furans during catalyst deactivation suggests a method for tuning the product distribution by altering the parent zeolite catalyst via changes in acidity and/or incorporation of alkali metals known to accumulate on the catalyst during pyrolysis. Here, we report the catalytic fast pyrolysis of three biomass ...

Production of renewable aromatic hydrocarbons via conversion of canola oil methyl ester (CME) over zinc promoted HZSM-5 catalysts

The conversion of canola oil methyl ester (CME) to aromatics was studied over Zn-modified HZSM-5 catalysts. The catalysts were prepared by incipient wetness impregnation method. Several techniques were used in characterization of the catalysts: X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption and ammonia temperature-programmed desorption. The effects of reaction temperature and Weight Hourly Space Velocity (WHSV) on the aromatics yields were investigated. The reactor was operated at atmospheric pressure, temperatures of 400 and 450 °C and space velocities of 2 and 4 hr−1. The main products were liquid hydrocarbon product (LHP), gases and water. Gas Chromatography (GC) analysis was applied to determine the BTX content of the LHP. Similar aromatic products distributions were obtained in the presence of unpromoted as well as Zn-promoted HZSM-5 catalysts. Toluene was the major aromatic compound followed by para-meta xylenes and benzene. The addition of zinc species to HZSM-5 catalyst promoted the aromatization capacity of the catalyst. The maximum aromatic yield of 42.6% was achieved at 450 °C and 2 h−1 over 4Zn/ZS catalyst.

Level of Polycyclic Aromatic Hydrocarbon (Pahs) and Phenols in Meat Products Due to Processing Methods

ObjectivesHealth challenges may arise from eating meat products not properly processed. High temperature during smoking of meat products usually above 400°C, could result in production of Polycyclic Aromatic Hydrocarbon (PAHs) and Phenols. (PAHs) which could exhibit cancerous substance affecting human health while Phenols produced could contribute to meat flavor, aroma, taste and overall acceptability.Materials and MethodsTen kg of raw semimembranosus muscles of 2 yr old male White Fulani cattle was used and was differently cut into 2 kg each to produce Nigeria locally consumed meat products namely, Kundi, Kilishi, Balangu, Suya and Asun. Kundi products; meat was cut into 50- 80 g, oven-dried for 3 h at 170°C and smoked for 2 h at 220- 250°C. Kilishi products; meat was cut into 20cm by 25cm of 100 to 150 g, oven-dried for 5 h at 170°C and smoked dried for 2 h at 220- 250°C. Suya products; meat was cut 20 by 25cm of 100– 150 g, oven-dried for 1 h at 170°C and smoked dried for 30 min at 220– 250°C Asun products; meat was sliced into 10cm by 12cm of 40- 50 g, oven-dried 45 min at 170°C and smoke dried for 30 min at 220- 250°C. Balangu products; meat was sized into 10- 12cm of 40 –50 g, oven-dried for 45 min at 170°C and smoke dried for 30 min at 220- 250°C. Final samples were evaluated and compared with the commercial product for PAHs, phenols, proximate composition and palatability status using a completely randomized design in a factorial experiment.ResultsKundi from LTSM and CM, and Kilishi from CM had the highest PAHs level (8.00µkg–1, 8.80µkg–1, and 8.60µkg–1) respectively, while the least (P < 0.05) values (2.10µkg–1) were observed in Asun products produced using all processing methods. Kilishi from CM had the highest phenols level of (1.30µg), and least value (0.10µg) was noticed in Asun products using all processing methods. Kundi products had the highest significantly (P < 0.05) values in protein and ash content in all the processing methods. Balangu products had the highest (P < 0.05) ether extract content, while moisture content was highest in Asun products. The panelists rated Balangu, Asun and Kilishi products highest (P < 0.05) than Kundi and Suya products.ConclusionWith higher temperature and duration of time used in smoking animal products, the higher the accumulation the nutrients composition, Phenols compound and the PAHs content (which could affect human health, when consumed).Table 1The level of Polycyclic Aromatic Hydrocarbon (PAHs) status in Nigeria meat products. (µkg-1)Method1KundiKilishiBalanguSuyaAsunSEMLTM8.00a6.40b2.50f3.20e2.10f0.001LOM3.30e5.30c2.10f2.20f2.10f0.001CM8.80a8.60a4.80d3.80e2.10f0.001a-fMeans of different alphabet in both the column and row are significantly different (p < 0.05).1LTM– Laboratory traditional smoking method; LOM- Laboratory oven dried method; CM- Commercial methods.

One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: insights into the major reaction pathways

For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Brønsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Brønsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.

Tandem μ-reactor-GC/MS for online monitoring of aromatic hydrocarbon production via CaO-catalysed PET pyrolysis

Online monitoring of products by a tandem μ-reactor-GC/MS system revealed the CaO catalysed PET pyrolysis pathway.

Enhanced Production of Aromatic Hydrocarbons by Rapeseed Oil Conversion over Ga and Zn Modified ZSM-5 Catalysts

Rapeseed oil conversion has been investigated over catalysts based on Ga- and Zn-modified nanocrystalline HZSM-5 zeolite aimed to the production of hydrocarbons that could be used as both raw chemicals and/or fuels. The reactions have been carried out in a fixed bed reactor operating under nitrogen at 550 °C and atmospheric pressure. The incorporation of the metallic species to the parent zeolite was carried out by wetness-impregnation, resulting in a good metal dispersion, which is facilitated by the relatively high external surface area available in the nanocrystalline zeolitic support. This metal addition causes significant changes in the textural and acidic properties of the ZSM-5 zeolite. In all cases, a high deoxygenation degree of the raw oil was achieved through the formation of CO, CO2, and H2O, whereas the main products obtained were light olefins (mainly ethylene and propylene) and aromatic hydrocarbons (BTX). The incorporation of Ga and Zn in the parent zeolite increased the formation of gasol...