Pyrolyzer-gas Chromatography/mass Spectrometry Research Articles

Factors influencing synergistic pyrolysis of biomass and polypropylene for alcohols and hydrocarbon production

Results are presented on the co-pyrolysis of different blends of rapeseed stalk and plastic polypropylene (100:0, 75:25, 50:50, 25:75 and 0:100) using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS), independently. The effect of temperature (450, 550 and 650 °C) on the synergistic effect between rapeseed stalk and polypropylene at different blend ratios as well as on the yield and amounts of alcohols and hydrocarbons produced are presented. The thermogravimetric analysis results showed that at the same temperature, increase of polypropylene in the mixture, gradually increased the intensity and rate of pyrolysis reaction. The weight loss data revealed improved pyrolysis during the process. The Fourier transform infrared spectroscopy results showed that the transmittance of ketones, esters and acids increased while the content of ketones, esters and acids decreased with increased polypropylene in the mixture. The pyrolyzer-gas chromatography/mass spectrometry results showed that temperature and feedstock mixture ratio had an impact on the yield and amounts of alcohols and hydrocarbons. The pyrolysis effect was most favorable at 550 °C temperature and rapeseed stalk/polypropylene mixture ratio of 1:3. These results provide some practical insights on clean energy recovery from mixtures of agricultural residues and waste plastics using thermochemical conversion.

Optimization of influencing factors during co-pyrolysis of biomass and plastics with focus on monocyclic aromatic hydrocarbons content

The thermal conversion of organic solid waste is a relatively economical and feasible method to obtain monocyclic aromatic hydrocarbon. In order to clarify the effect of different temperature, blend ratio and reaction time on the monocyclic aromatic hydrocarbon content during the co-pyrolysis of biomass and plastics, and to seek the best experimental conditions, maize stalk and polystyrene plastic were used as raw materials to analyze the content of monocyclic aromatic hydrocarbons by pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). At the same time, based on the Response Surface Methodology of Central Composite Design, a quadratic regression equation for the co-pyrolysis of maize stalk and polystyrene with focus on content of monocyclic aromatic hydrocarbon was established through the response surface optimization experiment of three factors and three levels. Variance analysis showed that the regression model was significant. The order of influencing factors from high to low on monocyclic aromatic hydrocarbon content was temperature, blend ratio of maize stalk to polystyrene, and reaction time. The optimal experimental conditions were temperature 600 ℃, blend ratio 1:3, reaction time 10.246 s, and the simulated content of monocyclic aromatic hydrocarbons was 68.99%. Based on actual situation, the optimum experimental conditions were temperature 600 ℃, blend ratio 1:3, reaction time 10 s, the theoretical and experimental content of monocyclic aromatic hydrocarbon were 68.31% and 65.68%, respectively. And the error among the simulated, theoretical, and experimental content is also within a reasonable range.

Unveiling Fragmentation of Plastic Particles during Biodegradation of Polystyrene and Polyethylene Foams in Mealworms: Highly Sensitive Detection and Digestive Modeling Prediction.

It remains unknown whether plastic-biodegrading macroinvertebrates generate microplastics (MPs) and nanoplastics (NPs) during the biodegradation of plastics. In this study, we utilized highly sensitive particle analyzers and pyrolyzer-gas chromatography mass spectrometry (Py-GCMS) to investigate the possibility of generating MPs and NPs in frass during the biodegradation of polystyrene (PS) and low-density polyethylene (LDPE) foams by mealworms (Tenebrio molitor larvae). We also developed a digestive biofragmentation model to predict and unveil the fragmentation process of ingested plastics. The mealworms removed 77.3% of ingested PS and 71.1% of ingested PE over a 6-week test period. Biodegradation of both polymers was verified by the increase in the δ13C signature of residual plastics, changes in molecular weights, and the formation of new oxidative functional groups. MPs accumulated in the frass due to biofragmentation, with residual PS and PE exhibiting the maximum percentage by number at 2.75 and 7.27 μm, respectively. Nevertheless, NPs were not detected using a laser light scattering sizer with a detection limit of 10 nm and Py-GCMS analysis. The digestive biofragmentation model predicted that the ingested PS and PE were progressively size-reduced and rapidly biodegraded, indicating the shorter half-life the smaller plastic particles have. This study allayed concerns regarding the accumulation of NPs by plastic-degrading mealworms and provided critical insights into the factors controlling MP and NP generation during macroinvertebrate-mediated plastic biodegradation.

Body distribution and ecotoxicological effect of nanoplastics in freshwater fish, Zacco platypus

The increased consumption of plastics worldwide, has led to the emergence of nanoplastics as important environmental pollutants. Despite the presence of nanoplastics in aquatic environments, their effects on ecosystems remain largely unexplored due to the analysis complexity. This study investigated the organ accumulation and toxic effects of 50 nm polystyrene nanoplastics (PS-NPs) in Zacco platypus (Z. platypus; also known as pale chub fish) using pyrolyzer-gas chromatography-mass spectrometry (Pyr-GC/MS). PS-NPs accumulated in Z. platypus’ brain, digestive tract, branchia, and liver, causing changes at cellular level. Over a 14-day exposure, the accumulated PS-NPs led to observable changes in fish behavior (e.g., Total traveled distance and maximum velocity). In addition, the oxidative stress in each organ of Z. platypus increased as the exposure concentration of PS-NPs increased. This study shows that accumulation of nanoplastics in fish, resulting in behavioral changes and biochemical toxicity. As the pattern of change magnifies with exposure time and concentration, from a long-term perspective, the influence of nanoplastics on aquatic ecosystems become evident. This underscores the urgency for continuous research into the potential risks of nanoplastics in aquatic ecosystems.

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.

Influence of CaO on the thermal kinetics and formation mechanism of high value-added products during waste tire pyrolysis

There is a lack of detailed research on the production of isoprene and D-limonene by solid base-catalysed thermal depolymerization of waste tires (WTs). This work aimed to investigate the thermal decomposition characteristics, reaction kinetics, high value-added products production and potential mechanisms during WT pyrolysis in the presence of calcium oxide (CaO) via Thermogravimetry-Fourier Transform Infrared spectrometer (TG-FTIR) and Pyrolyzer-Gas Chromatography/Mass spectrometry (Py-GC/MS). The results obtained from TG indicated that CaO accelerated depolymerization in terms of reducing the reaction temperature, which is also reflected in the kinetic parameters. It can be found that the content of D-limonene increased by 13.76% and that of isoprene increased by 37.57%, which were attributed to differences in the depolymerization mechanisms in the presence of CaO. Furthermore, CaO had a profound impact on desulfurization by reducing benzothiazole, sulfoacid, and thiophene. The potential catalytic mechanisms of isoprene and D-limonene production and desulfurization were also proposed. This work deepens the understanding of the catalytic pyrolysis of WT under CaO and unambiguously demonstrates the great potential of CaO in enhancing isoprene and D-limonene production, providing new insight for the cleaner production of high value-added products from WT.

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.

Co-hydrothermal carbonization of cellulose, hemicellulose, and protein with aqueous phase recirculation: Insight into the reaction mechanisms on hydrochar formation

Co-hydrothermal carbonization (Co-HTC) coupled with aqueous phase (AP) recirculation has huge potential to improve hydrochar production. In this study, three model compounds, namely wheat straw cellulose (cellulose, Ce), xylan (hemicellulose, He), and soya-protein (protein, Pr), were processed by HTC individually or Co-HTC in combination, with or without AP recirculation. Hydrochar formation behavior was investigated through analysis of hydrochar and AP by elemental analysis, X-ray photoelectron spectroscopy (XPS), Pyrolyzer-gas chromatography-mass spectrometry (Py-GC-MS), GC-MS, and a series of other characterizations. Elemental compositions reveal that both Co-HTC and AP recirculation promoted hydrochar formation and reduction of oxygen in hydrochar, and the combination promoted these effects. Furthermore, XPS and Py-GC-MS results show that the building blocks of hydrochar were oxygenated compounds from Ce and He such as furans and furfurals, and nitrogen-containing compounds from Pr such as amino acids and N-heterocycles. Subsequently, hydrochar formation mechanisms were proposed by results from GC-MS analysis of AP and the above observations. The major mechanisms account for enhanced hydrochar formation during Co-HTC with AP recirculation were Maillard reaction occurred between amino acids and saccharides, catalytical effects (mainly on Maillard reaction) from acids in the recycling AP, and the repolymerization or condensation of accumulated compounds in AP.

Chemical Feedstock Recovery via the Pyrolysis of Electronically Heated Tobacco Wastes

The pyrolysis of waste electronically heated tobacco (EHT), consisting of tobacco leaves (TL), a poly-lactic acid (PLA) filter, and a cellulose acetate (CA) filter, was investigated using thermogravimetric (TG) and pyrolyzer–gas chromatography/mass spectrometry (Py-GC/MS) analysis. The pyrolytic properties of waste EHT obtained after smoking were comparable to those of fresh EHT. Although the maximum decomposition temperatures (TmaxS) of waste TL and CA were similar to those of fresh EHT components, the Tmax of waste PLA was slightly higher than that of fresh PLA due to smoldering. The Tmaxs of PLA and CA were lowered when they were co-pyrolyzed with TL due to interactions between pyrolysis intermediates. The apparent activation energies for the non-isothermal pyrolysis of waste EHT components were higher than those of fresh EHT components. Py-GC/MS analysis results indicated that considerable amounts of chemical feedstocks, such as nicotine and limonene from TL, caprolactone and lactide from PLA, and acetic acid and triacetin from CA, can be recovered by simple pyrolysis of EHT. Co-pyrolysis of TL, PLA, and CA revealed that the experimental amount of lactide was much larger than the calculated value, suggesting its synergistic formation.

Catalytic Pyrolysis of Waste Achyranthes Root Over Al-MCM-41.

This study examined the thermal and catalytic pyrolysis of waste Achyranthes Root (AR) using pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). The non-catalytic pyrolysis of waste AR produced various kinds of oxygenates, such as acetic acid, hydroxy propanone, furfural, phenol, cresol, guaiacols, syringols, and so on. By applying nanoporous Al-MCM-41 with acidic properties and mesopores to the pyrolysis of waste AR, the levels of furan and aromatic hydrocarbons production increased with a concomitant decrease in the other oxygenates. The formation efficiency of furans was improved further by increasing the amount of Al-MCM-41 applied to the catalytic pyrolysis of waste AR.

Effect of desilication of HZSM-5 on the catalytic pyrolysis of polystyrene

Desilicated HZSM-5 (DeHZSM-5) was prepared by the desilication of HZSM-5 (SiO2/Al2O3: 30) and applied to the catalytic pyrolysis of polystyrene (PS) by thermogravimetric analysis (TGA) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). TGA showed that HZSM-5 lowered the decomposition temperature and apparent activation energies of PS. DeHZSM-5 led a lower decomposition temperature and Ea values than HZSM-5. The main pyrolyzates of PS, styrene monomer, dimer, and trimer, were converted to smaller aromatic hydrocarbons, such as benzene and toluene. The increased pore size and acidity of DeHZSM-5 formed by the desilication of HZSM-5 led to the efficient diffusion of large molecular pyrolyzates with the increased formation of smaller molecular aromatic hydrocarbons confirming the higher catalytic cracking efficiency.

The effect of seawater aging on the pyrolysis of fishing nets

This study examined the effects of seawater aging on the physicochemical properties and pyrolysis behavior of nylon-6 (N6) and polyethylene (PE) using Fourier transform infrared (FT-IR) spectroscopy, X-ray fluorescence spectroscopy, thermogravimetric analysis (TGA), and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). The analyses revealed an increase in the contents of fixed carbon and ash in both N6 and PE due to aging in seawater for five months. FT-IR spectroscopy indicated an increase in the content of the hydroxyl group in the structures of both aged N6 and PE, suggesting their partial decomposition and oxidation during seawater aging. TGA showed that the maximum decomposition temperature (Tmax) and pyrolysis kinetic parameters of N6, such as the activation energy and pre-exponential factor, were changed by seawater aging. Although the Tmax of PE did not change significantly with seawater aging, the differential thermogravimetric peak shape and kinetic parameters of PE were changed by seawater aging. The isothermal Py-GC/MS results at 600 °C showed that aged N6 produced 3-amino-pentanol in addition to the typical pyrolyzates of fresh N6. Furthermore, the pyrogram of aged PE was similar to that of fresh PE.

P.775 Worms from the brain: treatment challenges in delusional parasitosis - a case report

As one of the major products from cellulose pyrolysis, levoglucosan (LG) is highly oxygenated and stubborn, causing serious problems to bio-oil utilization. In this study, catalytic ketonization of LG over nano-CeO2 was performed in a pyrolyzer-gas chromatography/ mass spectrometry (PY-GC/MS) system to prepare hydrocarbon precursors (principally ketones). Nano-CeO2 has been proven effective to convert LG into ketones, with the highest selectivity (71.2 %) obtained when CeO2 to LG ratio was 15:1 (mm3: mg) at 700 °C. When 5% ZrO2 was loaded on CeO2 (5% Zr/CeO2), the selectivity of ketones further increased to 76.0 %, and that of linear compounds in all the ketone products reached 53.9 %. Results from catalyst characterization revealed that 5% Zr/CeO2 contained an abundance of basic surface sites and redox capacity, thus leading to high ketonization activity. Ketonization of LG possesses significant potential in facilitating the conversion of cellulose into high-quality biofuels in a sustainable way.

Catalytic ketonization of levoglucosan over nano-CeO2 for production of hydrocarbon precursors

As one of the major products from cellulose pyrolysis, levoglucosan (LG) is highly oxygenated and stubborn, causing serious problems to bio-oil utilization. In this study, catalytic ketonization of LG over nano-CeO2 was performed in a pyrolyzer-gas chromatography/ mass spectrometry (PY-GC/MS) system to prepare hydrocarbon precursors (principally ketones). Nano-CeO2 has been proven effective to convert LG into ketones, with the highest selectivity (71.2 %) obtained when CeO2 to LG ratio was 15:1 (mm3: mg) at 700 °C. When 5% ZrO2 was loaded on CeO2 (5% Zr/CeO2), the selectivity of ketones further increased to 76.0 %, and that of linear compounds in all the ketone products reached 53.9 %. Results from catalyst characterization revealed that 5% Zr/CeO2 contained an abundance of basic surface sites and redox capacity, thus leading to high ketonization activity. Ketonization of LG possesses significant potential in facilitating the conversion of cellulose into high-quality biofuels in a sustainable way.

Determination of Polyvinyl Acetate in Chewing Gum Using High-Performance Liquid Chromatography-Evaporative Light Scattering Detector and Pyrolyzer-Gas Chromatography-Mass Spectrometry.

Polyvinyl acetate (PVAc) is used in various adhesive, paint, and transparent tape applications. It is also used as a food additive in food manufacturing to make chewing gum and fruit and vegetable glazes; however, guidelines on the amount of food additives that is used have not yet been established. In this study, a method was developed for analysis of polyvinyl acetate (PVAc) using high-performance liquid chromatography with an evaporative light scattering detector (HPLC–ELSD) and pyrolyzer–gas chromatography–mass spectrometry (Py–GC–MS). The analytical methods were applied to commercially available chewing gum. In the HPLC–ELSD analysis, the linearity was acceptable (R2 > 0.999), and the limits of detection and quantification were 22.2 and 67.3 µg/mL, respectively. The accuracies of PVAc were 87–115% at spike levels of 200–1000 µg/mL for the intra- and inter-day tests. The contents of PVAc in the chewing gum samples were n.d. (not detected)—13.8 g/kg. The presence of PVAc in chewing gum was verified with Py–GC–MS analysis, finding the typical pyrolysates of PVAc, such as acetic acid, benzene, toluene, styrene, indane, naphthalene, and acenaphthene. The developed analytical methods can be applied for successful identification of PVAc in chewing gum.

Co-feeding effect of waste plastic films on the catalytic pyrolysis of Quercus variabilis over microporous HZSM-5 and HY catalysts

The co-pyrolysis of Quercus variabilis (Q. variabilis) and waste plastic films (PFs) was investigated to evaluate the co-feeding effect of waste PFs to the pyrolysis of Q. variabilis. Thermogravimetric analysis results revealed that the second TG (DTG) peak temperature of waste PFs was decreased from 479 °C to 470 °C by applying its co-pyrolysis with Q. variabilis, suggesting the effective interaction between the pyrolysis intermediates of Q. variabilis and waste PFs. Pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) analysis results showed that the typical pyrolyzates of Q. variabilis and waste PFs were not changed during for their thermal co-pyrolysis. In contrast, the catalytic co-pyrolysis (CCP) of Q. variabilis and waste PFs in Py-GC/MS resulted in the additional aromatics formation, suggesting that the interaction between the pyrolysis intermediates of Q. variabilis and waste PFs over both HY and HZSM-5 leads to the enhanced formation of aromatics. Owing to the higher acidity and proper pore structure of HZSM-5, the CCP of Q. variabilis and waste PFs over HZSM-5 achieved higher aromatic and lower coke formation efficiency than that over HY.

Pyrolysis of Millettia (Pongamia) pinnata waste for bio-oil production using a fly ash derived ZSM-5 catalyst

Fast pyrolysis of Millettia (Pongamia) pinnata waste (PPW) was performed using a scaled-up 180-cm drop-tube pyrolyzer with fly ash (FA)-derived ZSM-5 (FA-ZSM-5) as a deoxygenation and denitrogenation catalyst to upgrade the liquid products. The oil from P. pinnata is typically extracted to produce bio-fuel leaving a large amount of PPW that has some 20% (v/v) oil content. Since the PPW is inedible, due to its toxicity from karanjin and di-ketone pongamol, it represents a potential non-food competing ‘green’ biofuel feedstock. The FA-ZSM-5 catalyst applied in this work was synthesized using alkali hydrothermal treatment of coal FA to yield FA-ZSM-5 with a 329 m2/g surface area and 37.18 Å pore diameter. Pyrolyzer-gas chromatography-mass spectrometry was used to locate the optimal operating window prior to executing a scaled-up reactor operation at 400–700 °C). A maximum bio-oil yield of 43.1% by proportion was obtained at 500 °C, while the solid and gas products were 32.5% and 24.4%, respectively. Oleic acid was a major component in the bio-oil obtained from the non-catalytic condition, while ketones were prominent (79.4%) when FA-ZSM-5 was used, albeit with a low hydrocarbon (HC) selectivity. From the carbon chain length analysis, thermal cracking to smaller molecules was dominant in the presence of the FA-ZSM-5 catalyst, inducing a low HC yield in the liquid product.

Catalytic Co-Pyrolysis of Kraft Lignin with Refuse-Derived Fuels Using Ni-Loaded ZSM-5 Type Catalysts

The catalytic co-pyrolysis (CCP) of Kraft lignin (KL) with refuse-derived fuels (RDF) over HZSM-5, Ni/HZSM-5, and NiDHZSM-5 (Ni/desilicated HZSM-5) was carried out using pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) to determine the effects of the nickel loading, desilication of HZSM-5, and co-pyrolysis of KL with RDF. The catalysts were characterized by Brunauer–Emmett–Teller surface area, X-ray diffraction, and NH3-temperature programed desorption. The nickel-impregnated catalyst improved the catalytic upgrading efficiency and increased the aromatic hydrocarbon production. Compared to KL, the catalytic pyrolysis of RDF produced larger amounts of aromatic hydrocarbons due to the higher H/Ceff ratio. The CCP of KL with RDF enhanced the production of aromatic hydrocarbons by the synergistic effect of hydrogen rich feedstock co-feeding. In particular, Ni/DHZSM-5 showed higher aromatic hydrocarbon formation owing to its higher acidity and mesoporosity.

Catalytic Pyrolysis of Polyethylene and Polypropylene over Desilicated Beta and Al-MSU-F

The catalytic pyrolysis (CP) of different thermoplastics, polyethylene (PE) and polypropylene (PP), over two types of mesoporous catalysts, desilicated Beta (DeBeta) and Al-MSU-F (AMF), was investigated by thermogravimetric analysis (TGA) and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). Catalytic TGA of PE and PP showed lower decomposition temperatures than non-catalytic TGA over both catalysts. Between the two catalysts, DeBeta decreased the decomposition temperatures of waste plastics further, because of its higher acidity and more appropriate pore size than AMF. The catalytic Py-GC/MS results showed that DeBeta produced a larger amount of aromatic hydrocarbons than AMF. In addition, CP over AMF produced a large amount of branched hydrocarbons.

Analytical pyrolysis reaction characteristics of Porphyra tenera

The non-isothermal pyrolysis of red algae (Porphyra tenera) was studied via thermogravimetric (TG) analysis in combination with two types of analytical pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS) techniques, namely, evolved gas analysis (EGA)-MS and multi-shot Py-GC/MS. The TG and model-free kinetic analyses revealed that the pyrolysis of P. tenera proceeded via the independent decomposition of carbohydrates, proteins, and lipids. Differential TG and EGA-MS indicated the existence of three decomposition temperature regions. In the first temperature region (<300 °C), carbohydrates were mainly decomposed. Large amounts of pyrolyzates of proteins and lipids such as toluene, phenols, aromatic amino acids, and hexadecanoic acid were produced in the second temperature region (301–380 °C). In the third region (>380 °C), large amounts of aromatic hydrocarbons and alkanes were obtained by the secondary cracking of the pyrolyzates of proteins and lipids.