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Compared with conventional pyrolysis, microwave pyrolysis has superior heat transfer performance and promotes the decomposition of organic matter. The paper focuses on the harmless treatment and resource utilization of pharmaceutical sludge (PS) by microwave heating and conventional heating methods. The experimental results showed that the conventional pyrolysis gas is dominated by CO 2 , CO and H 2. For microwave pyrolysis gas, the "microwave effect" promoted secondary cracking of volatile fractions and increases the content of CH 4 , C x H y , H 2 and CO through condensation, aromatization, and dehydrogenation. Conventional pyrolysis oils contained the highest percentage of oxygenated compounds. However, high-temperature microwave radiation accelerated the cleavage of polar oxygenated molecular bonds and long-chain hydrocarbons, thereby increasing the aromatics content of pyrolysis oils. The solid residues obtained from microwave pyrolysis is highly graphitized and porous, with a surface area of 146.2 m2/g. Furthermore, the solid residue was rich in pyridine-N and pyrrole-N that could be utilized for adsorption and catalysis. The MA-600 removes up to 99% of tetracycline (TC) in 6 h. It was also found that the adsorption process of TC by the two pyrolysis residues was consistent with the proposed secondary and Freundlich models. [Display omitted] • Microwave pyrolysis oil has a smaller carbon number. • Hot spots and dehydrogenation are key factors in increasing C x H y yields. • Microwave pyrolysis residue surfaces are dominated by pyrrole nitrogen. • Porosity of microwave pyrolysis residues facilitates TC adsorption. [ABSTRACT FROM AUTHOR]

In the present study, we pyrolyzed a waste tire at various temperatures under an N 2 atmosphere and a water environment in an autoclave reactor to investigate the effect of water on tire degradation. The analysis involved a comparison of product distribution, char properties, oil composition, and the behavior of heteroatom elements (especially oxygen, nitrogen, and sulfur) under different atmospheres. Elemental analysis, functional-group identification, and chemical state analysis of sulfur were performed for chars. In addition, the chemical composition, elemental composition, and molecular weight of the produced oils were evaluated. The heavy fraction of oils, not detectable by gas chromatography-mass spectrometry (GC-MS), was analyzed through Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The findings revealed that high temperatures promoted oil cracking, resulting in the formation of light oils in both pyrolysis and hydrolysis processes. Compared to pyrolysis, hydrolysis generated a higher yield of low molecular–weight oil. Elevated hydrolysis temperatures promoted aromatization, yielding an oil with a low H/C ratio and a high double bond equivalent number. Consequently, the concentration of aromatics in the light fraction of oils generated from the hydrolysis process exceeded that in oils from the pyrolysis process. Temperature exhibited a limited impact on oil composition during the pyrolysis process. Hydrolysis promoted the release of heteroatom-containing compounds at low temperatures. During pyrolysis, nitrogen was gradually released from the solid phase, whereas nitrogen-containing compounds were released early during hydrolysis, with gas-phase nitrogen accounting for more than 50 wt% at 320 °C. A maximum D-limonene yield of 45.58% was obtained at 360 °C within 0 min of hydrolysis, with the potential conversion of D-limonene into aromatics at higher hydrolysis temperatures. These results contribute to the understanding of tire valorization via hydrolysis. [Display omitted] • Higher temperatures can promote the formation of aromatics. • Hydrolysis promote the early release of nitrogen-containing compounds. • Higher hydrolysis temperatures can promote the formation of sulfide. • Temperature has a weak effect on oil composition for pyrolysis process. • Extensive of NxOy, NxOySz, NxSy, Nx and Ox classes formed. [ABSTRACT FROM AUTHOR]

Highlights • A novel hierarchical millisecond gas-phase catalytic cracking process was proposed. • Five catalysts were compared to study the selectivity of C 2 -C 4 hydrocarbons and BTX. • The maximum light olefins yield was obtained with 30% calcium aluminat/70% ZSM-5. • A bench-scale was used to verify the potential application of VR to chemicals. Abstract In order to enhance the production of light olefins from vacuum residue (VR), a novel hierarchical millisecond gas-phase catalytic cracking (HM-GCC) process was proposed. The process integrated the pyrolysis of VR and the catalytic cracking of the pyrolysis oil in the gas phase. Firstly, the effects of reaction temperature on the millisecond pyrolysis behavior of VR were investigated, and the results showed that the increase of C 2 -C 4 hydrocarbons content was not obvious when increasing the temperature from 600 to 750 °C. However, the thermal cracking as a pretreatment process converted the VR macromolecule into the low molecular pyrolysis oil. After that, five different catalysts calcium aluminate, FCC catalyst, and ZSM-5 zeolites (Z-40, Z-80, and Z-200) were investigated to evaluate their activities in catalytic cracking of pyrolysis oil, and among them Z-40 showed the highest selectivity for C 2 -C 4 hydrocarbons and BTX. For further study, the relative contents of C 2 -C 4 hydrocarbons were higher for the combination of calcium aluminate and Z-40 (Z + C-cat) than that of the pure Z-40 catalyst. This result was attributed to the fact that Z + C-cat facilitated the cracking of macromolecules and inhibited hydrogen transfer reactions. Finally, the conversion of VR and pyrolysis oil was studied in the bench scales with calcium aluminate and Z-40 catalyst. The yield of ethylene, propylene and butenes increased by 4.69, 7.87 and 3.37 wt% respectively in the presence of Z-40. [ABSTRACT FROM AUTHOR]

Abstract: This paper completes our work on calculation of a chemical-technological complex for coprocessing cracking and pyrolysis gases on the basis of a method developed for optimal design of a chemical-technological complex (CTC) with progressive fulfilment of steps aimed at optimizing the entire complex with consideration of the mutual influence of all its processes. Using the mathematical model of the entire CTC with complete kinetic models of all the selected processes as a basis, its optimization was performed and the optimal regimes with a maximum production capacity for all the target products were selected for these processes. Advisable routes of the motion of byproducts were selected. The resulting closed flowsheet of the chemical-technological complex with notations of all inlet and outlet flows and established couplings of material and recycled flows between all the reactor elements was presented. Using the complete mathematical model and the selected economic criterion and optimization method as a basis, the chemical-technological complex was subjected to global optimization and, as a consequence, the optimally consistent material flows of the entire complex were determined with the resulting maximization of its rate-of-return, i.e., an appreciable increase in the economic efficiency of CTC operation. [ABSTRACT FROM AUTHOR]

In this research, a global reaction model for the thermal cracking of China No.3 aviation kerosene was modeled based on experimental investigations under supercritical pressure. The result indicates that, when the conversion is lower than 50%, small molecules of products were generated nearly in a constant ratio and the selectivities of them were approximately identical. Therefore, a molecular kinetic model was developed using plug flow reactor model and an isothermal hypothesis. In order to estimate the kinetic parameters, a novel method of online density measuring was used to obtain the precise resident time. The reliability of this molecular kinetic model was validated through the comparison of experimental results with simulated values. [ABSTRACT FROM AUTHOR]

A thermal cracking experimental equipment of hydrocarbon fuels was built to study n-heptane pyrolysis and the effect of reaction conditions on this reaction process. The main species were measured and the change rules were analyzed on the range of temperature 873–1073 K and pressure 0.1–3.5 MPa. The total content of alkenes products was more than alkanes on this pyrolysis process. Compared to alkenes with same number carbons, the alkanes were more easy to decompose with temperature but more conducive to formation with pressure increasing. The content of ethylene is usually the most on above reaction conditions, but its descent is also the fastest with pressure increasing. A mechanism model of n-heptane pyrolysis (44 species and 166 reactions) was constructed and validated by experiments on different conditions. Compared with n-heptane oxidation detailed model of Version 3.1 from Lawrence Livermore National Laboratory (LLNL), the pyrolysis model present a better accordant with experiment results on a range of temperature and pressure. The kinetic reaction of n-heptane pyrolysis was analyzed with present pyrolysis model, and the pyrolysis reaction pathway for the main products was obtained. The formation of alkenes are mainly through C C bond dissociation reaction, especiallyβ-C dissociation, and small alkanes are formed mainly by radical metathetical or synthesis reaction, the former are endothermic reactions, but the latter are mostly exothermal reactions. The properties of some main reactions have a critical role for the change of product content with temperature and pressure, which is the main reason for the variety of products selectivity under different conditions. Pressure increased the pyrolysis residence time and mass density but it does not significantly affect the reaction energy, so its contribution to conversion rate of fuels thermal cracking is limited, although it changes the reaction pathway greatly. However, the temperature can increase obviously the reaction activation energy, even though the residence time and concentration is decreased, the conversion rate of n-heptane pyrolysis still increased. [ABSTRACT FROM AUTHOR]

Internal pores and fractures inside oil shale undergo complex changes during pyrolysis in superheated steam. After a simulated in-situ pyrolysis in superheated steam, the pore characteristics of 30 oil shale samples from different zones between the injection and production wells were investigated using mercury intrusion porosimetry (MIP). The results showed that the porosity of oil shale exceeded 27.65% in each position of horizontal fractures. In different types of pores, the proportions of mesopore (0.1 µm < d ≤ 1 µm) and micropore (d ≤ 0.015 µm) were the largest and the smallest, respectively. Moreover, mesopores outnumbered micropores. The pore structure of pyrolyzed oil shale after convection heating was complex. After the pyrolysis in superheated steam, the proportion of the oil shale ore body with a porosity ranging from 23 to 31% was 74.95% of total. This finding proved that oil shale was transformed from dense rock to a porous medium under the effect of superheated steam. [ABSTRACT FROM AUTHOR]

A novel strategy that combines steam reforming of bio-oil and recovering waste heat from blast furnace (BF) slag was proposed, and the thermodynamic characterizations of steam reforming of bio-oil model compounds recovering waste heat from BF slag for hydrogen production were investigated. When temperature ranged from 600 to 700 °C, hydrogen yield and its component reached maximum, about 100 mol kg−1 bio-oil model compounds and 70%, respectively. The higher mole ratio of steam to carbon in bio-oil (S/C), the higher hydrogen yield and its component were obtained, but according to the practical process, the most suitable S/C was 4. The ordinary pressure (1 bar) was considered as the optimum pressure for steam reforming of bio-oil model compounds recovering waste heat from BF slag. At lower temperatures (below 500 °C), BF slag could promote hydrogen yield, but it slightly decreased equilibrium yield of hydrogen at the optimal conditions. Besides, BF slag could promote hydrogen component at lower temperatures (below 600 °C), but it had little effect at the optimal conditions. Solid carbon should be reduced during steam reforming of bio-oil compounds recovering waste heat from BF slag. [ABSTRACT FROM AUTHOR]

This work aims to investigate the importance of biomass char and the metal oxides in the ash in tar cracking during the volatile-char interactions. Experiments were carried out in a two-stage fixed reactor, and corncob, one typical agricultural biomass rich in potassium, was chosen as raw material. Results showed that char and char-supported potassium catalysts have good activity for tar elimination due to the good absorbability of char and catalytic property of potassium. In particular, tar conversion efficiency can reach 95.8% by using 1.5 K-char catalyst at 700 °C. The reforming reactions can be significantly enhanced during the volatile-char interactions in the presence of char and char-supported potassium catalysts. As a result, the syngas yield increased significantly with increasing temperature and supported K, particularly the combustible gases including H, CO and CH. Physical and chemical structure of char changed due to reforming reactions related to the carbon, while the content of potassium was almost unchanged. [ABSTRACT FROM AUTHOR]

With the aim of investigating the solutions of ethane shortage in a commercial ethylene plant, addition of propane as supplementary feedstock and increasing steam to hydrocarbon ratio were proposed as possible strategies. These strategies were proposed to compensate for the ethane shortage in the thermal cracking unit of the commercial plant. Run length, ethylene yield, and propylene yield were considered as the determining factors to appraise the strategies. The major contribution of present work would be the investigation of effect of feed shift on the run length of the steam cracker. Regarding this, five different cases were investigated in real plant condition. To include all the aspects of process, a mathematical model with reasonable assumptions was developed and then validated against the real plant data. Based on the obtained results, increasing propane concentration leads to increase in propylene yield and decrease in ethylene yield. Besides, run length of process was obtained to be longer in the cases with higher propane content in the feed stream. [ABSTRACT FROM AUTHOR]

Joint thermal treatment of heavy oil and liquid products of fast wood pyrolysis is investigated. Thermal analysis shows that the coke yield does not increase if the liquid products are added up to 20 mass%. The liquid wood-pyrolysis products decompose much earlier than heavy oil. However, the decomposition of the blends is essentially the same as pure-oil decomposition. [ABSTRACT FROM AUTHOR]

Refining of high acid crudes (HACs) is seriously limited by extensive corrosion of refinery equipment due to the presence of intrinsic naphthenic acids (NAs). Herein, in the absence of a catalyst or external hydrogen, effective removal of the NAs contained in HACs was achieved using methanol at moderate temperature and moderate pressure. Several process variables, including the temperature, crude concentration, and reaction time are explored to optimize the removal of NAs from HACs. At 250 °C, 6.4 MPa, and 33.3 wt% crude, a very low total acid number (TAN) of 0.08 mg-KOH/g-oil (96.9% reduction efficiency) with a high oil yield (95 wt%) is achieved. During the reduction of the TAN using methanol, some fraction of the resins and asphaltenes in the crude oil crack to form low-molecular-weight aromatic compounds. Compared to deacidification using methanol, pyrolysis (without methanol) results in a much lower TAN reduction efficiency (38.6%). The major deacidification mechanism using methanol is esterification, while that of pyrolysis (without methanol) is decarboxylation. [ABSTRACT FROM AUTHOR]

The influence of modifiers affecting the structural organization of a petroleum system and the kinetics of oxidation of vacuum distillation bottoms have been studied. It has been shown that the introduction of modifiers into the petroleum feedstock alters the ratio of the dispersed phase to the dispersion medium, thereby affecting the rate of the oxidation process. It has been found that the main factor determining the performance of modifiers affecting the structure of the petroleum system is the modifier nature. The maximum concentration of modifiers in the vacuum tower bottoms (VTB) was 5.0 wt %. The dependence of the oxidation rate upon the duration of oxidation has been determined for the modifiers. It has been shown that brown-coal pyrolysis tar introduced into VTB has an inhibitory effect, and oil shale pyrolysis tar and a diamond blend initiate the oxidation process. For blown asphalts produced from modified and unmodified VTB, expressions relating the softening point and penetration have been obtained. The properties of different blown asphalts obtained from the feedstock modified with the test additives at optimal concentrations have been compared. [ABSTRACT FROM AUTHOR]

Heavy oil is less expensive than light crude oil, but heavy oil is more expensive to obtain light oil products. Conventional light crude oil resources are decreasing, therefore heavy oil resources will be needed more in the future. There are huge differences from field to field for heavy oil deposits. In terms of final productive use, heavy oil is considered as an unconventional resource. Heavy oil upgrading depends on four important factors: catalyst selection, heavy oil classification, process design, and production economics. Heavy and extra-heavy oils are unconventional reservoirs of oil. Globally, 21.3% of total oil reserves are heavy oil. Heavy oil is composed of long chain organic molecules called heavy hydrocarbons. The thermal degradation of the heavy hydrocarbons in heavy oil generates liquid and gaseous products. All kinds of heavy oils contain asphaltenes, and therefore are considered to be very dense material. The most similar technologies for upgrading of heavy oils are pyrolysis and catalytic pyrolysis, thermal and catalytic cracking, and hydrocracking. The amount of liquid products obtained from pyrolysis of heavy oil was dependent on the temperature and the catalyst. Pyrolytic oil contains highly valuable light hydrocarbons as gasoline and diesel components range. The constant increase in the use of crude oils has raised prices of the most common commercial conventional products and consequently seeking for new alternative petroleum resources, like some unconventional oil resources, becomes an interesting issue. The mass contents of gasoline, diesel, and heavy oil in the crude oil are 44.6%, 38.3%, and 17.1%, respectively. The gasoline yield from the heavy oil catalytic (Na2CO3) pyrolysis is higher than the diesel efficiency for all conditions. The yield of gasoline products increases with increasing pyrolysis temperature (from 230°C to 350°C) and percentage of catalyst (from 5% to 10%). The yields of gasoline-like product are from 21.5% to 39.1% in 5% catalytic run and from 32.5% to 42.5% in 10% catalytic run. The yields of diesel-like product are from 9.3% to 29.8% in 5% catalytic run and from 15.5% to 33.7% in 10% catalytic run. [ABSTRACT FROM AUTHOR]

To create a chemical-technological complex for the joint processing of cracked gases and pyrolysis gases, the technique of its design was developed. Based on the design capacity of the pyrolysis and cracking units, mass flows of cracked gases and pyrogas entering the chemical-technological complex have been calculated. A scheme has been developed for the proposed complex. To reduce the dimension of the design task, the whole complex was divided into a separate region. Based on the stoichiometric and kinetic models, the calculation of material balances for all processes included in the largest ethylene region has been carried out. The technological parameters were taken from the operated industrial units and processes on the stage of design. The industrial productivity of reactor elements by the targeted products has been determined. [ABSTRACT FROM AUTHOR]

The bio-oil from rice hull fast pyrolysis was distillated under reduced pressure at 0.005 Mpa, then mixed with ethanol (2:3 by weight). The mixture was subjected to catalytic co-cracking over Ni-ZSM-5/MCM-41 molecular sieves in a fixed-bed at 500 °C and 3.75 h −1 of the WHSV. The distillation results showed the distilled bio-oil, compared with raw bio-oil, contained lower oxygen content (decreased from 45.91 wt.% in raw bio-oil to 33.74 wt.%), higher (H/C) eff ratio (0.35) and HHV value (22.81 MJ/kg). The ethanol was involved in the ketonization, esterification, aromatization and dehydration during the catalytic co-cracking of distilled bio-oil and ethanol. The Ni loaded on ZSM-5/MCM-41 molecular sieves reduced char formation compared with ZSM-5/MCM-41. The ZSM-5/MCM-41 catalyst exhibited higher activity in the esterification and aromatization, which converted acids in upgraded bio-oil to esters, aromatics or phenols. The Ni-ZSM-5/MCM-41 catalysts showed excellent activity that transformed acids to ketones by ketonization process. The 6% Ni-ZSM-5/MCM-41 catalyst performed the good activity with the minimum char formation (7.3 wt.%) and higher upgraded bio-oil (40.8 wt.%). Moreover, the acid content in the upgraded bio-oil dropped to 0.1 wt.% and the total concentration of CO 2 and CO in the gas products was 36.8 vol.%. [ABSTRACT FROM AUTHOR]

The study evaluated the growth of Desmodesmus communis on column photobioreactor and its thermochemical treatment by catalytic pyrolysis using HZSM-5 zeolite. D. communis showed good results in terms of growth (0.05g L −1 d −1 ). Analytical pyrolysis of original algae and derived bio-oil mixed with zeolite was used as a screening method in order to gather information on the cracking process. Preparative pyrolysis on bench scale reactor was performed on algae biomass over a zeolite bed at 1:10 ratio (wt/wt). Py-GC–MS of biomass/catalyst mixture showed that the denitrogenation/deoxygenation increased with increasing zeolite load from 1:5 to 1:20 ratio and became significant at 1:10 ratio. The composition observed by analytical pyrolysis was featured by the predominance of alkylated monoaromatic hydrocarbons. The scaling-up to bench scale confirmed the results obtained with analytical pyrolysis in terms of monoaromatic hydrocarbons. However, low yield of catalytic oil (8% by weight) was observed. [ABSTRACT FROM AUTHOR]

Hydrogen production by methane cracking over a set of demineralised Xiaolongtan lignite chars, with and without the addition of various inorganic species, has been studied using a fixed bed reactor at atmospheric pressure and 1123 K in order to study the catalytic effect of mineral matter on methane cracking. The raw lignite char was prepared by pyrolysing a Xiaolongtan lignite sample in nitrogen in the fixed bed reactor at 1173 K for 30 min. Of the two demineralised chars, one (Char 1) was prepared by washing the parent lignite sequentially with 5 N HCl, 29 N HF and 12 N HCl before pyrolysis while the other (Char 2) was prepared by washing the raw lignite char. For comparison, a variety of inorganic species were added into Char 1 via incipient impregnation. NaCl was added into Char 1 at a sodium content varying from 0.1 wt% to 0.3 wt%. CaCl 2 , FeCl 3 , KCl, and MgCl 2 were also added into Char 1, respectively, with the corresponding metal content being 0.1 wt% in the chars. The methane cracking experiments showed that hydrogen was the primary gas product. The demineralised chars were less effective in catalysing methane cracking than the raw char, suggesting that the mineral matter indeed promoted methane cracking. Char 2 showed higher catalytic activity than Char 1, due to its relatively higher mineral matter content and greater BET surface area. Carbon deposition during methane cracking resulted in deactivation of the chars by blocking the pores and reducing the surface areas. The added inorganic species at trace amounts in the demineralised Char 1 also enhanced the methane conversion and hydrogen yield. With increasing sodium addition up to 0.3 wt%, the catalytic effect of the char increased first and then decreased. In terms of the methane conversion, the catalytic effect of the inorganic species added into Char 1 followed the order of NaCl > CaCl 2 ≈ FeCl 3 > MgCl 2 ≈ KCl. However, the various inorganics showed no difference in enhancing hydrogen yield. [ABSTRACT FROM AUTHOR]

A detailed kinetic model consisting of 833 reactions has been developed to describe the thermal cracking of n -butylcyclohexane at high pressure (100 bar). A primary mechanism was written in an exhaustive manner whereas a partial secondary mechanism was considered to describe the formation and the consumption reactions of aromatic compounds. The model was tested against our experimental data for BCH pyrolysis at 100 bar in the temperature range 375–425 °C. A global agreement was reached for BCH conversion up to 50% for both conversion and product yields e.g. propane, cyclohexane and toluene. Flow analysis of the proposed mechanism at a conversion of 35% shows that both alkanes (i.e. methane, ethane, propane and n -butane) and cycloalkanes (i.e. cyclohexane, methylcyclohexane and ethylcyclohexane) mainly come from the breaking of the side alkyl chain. The production of butylbenzene is due to the direct dehydrogenation of BCH whereas other alkylaromatic compounds i.e. benzene, toluene and ethylbenzene seem to come from the breaking of the side alkyl chain of butylbenzene rather than aromatization of cycloalkanes or alkylcyclohexenes. At 100 bar and around 400 °C, breaking of alkyl side chain reactions prevail on dehydrogenation reactions and ring opening. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the products of homogeneous cracking of rice husk tars and to investigate the conditions for production of hydrogen rich syngas. Experiments were performed in a two-stage downdraft fixed-bed gasifier as a function of temperature and residence times. Tars were generated with a medium heating rate of 25 K/min in a pyrolysis section of the gasifier. Generated tars were subsequently cracked by secondary reactions in gasification section. Tar conversion of about 91% was achieved. Tar cracking at higher temperatures resulted in the formation of hydrogen rich syngas. Secondary product yields and their kinetics were studied for tar cracking and individual gas formed by single-reaction model and distributed activation energy model. A good fit of the data was obtained with the single-reaction model; however distributed activation energy model correlated the tar cracking kinetic parameters more closely than single-reaction model. [ABSTRACT FROM AUTHOR]

Two-step hydrotreatment experiments were performed using three completely different bio-oil fractions namely: whole bio-oil, heavy bio-oil obtained after fractional condensation of pyrolysis vapours and pyrolytic lignin obtained by cold water precipitation of the bio-oil. The aim is to study the de-oxygenation and in addition SEC and UV-fluorescence analysis was used to identify the importance of cracking, polymerization and hydrogenation reactions of the three different bio-oil feedstocks. In the first step hydrotreatment, Ru/C was used at 250 or 300 °C with reaction time of 2 h. In the second step hydrotreatment, Ni-Mo/Al 2 O 3 catalyst was used at 375 or 400 °C, with reaction time of 2 or 4 h. During stabilization in the first step, pyrolytic lignin was hydrogenated to a large extent accompanied by cracking reactions. In the second step, unsulphided Ni-Mo/Al 2 O 3 catalyst was active enough to effectively crack pyrolytic lignin into smaller molecules. High molecular weight compounds including large aromatic ring structures were formed from the reactive sugar rich fraction in both first step stabilization and second step hydrotreatment. The newly formed polymerization products were difficult to crack even at extended reaction times of 4 h at 400 °C. Importantly, the presence of water (and light oxygenates) could significantly supress the polymerization reactions. [ABSTRACT FROM AUTHOR]

Underground coal gasification (UCG) allows in situ conversion of unmineable coal deposits into a combustible gas. UCG involves a number of steps, including combustion, oxidation–reduction (REDOX) reactions, pyrolysis, and drying, within the gasification channel at high temperatures. Pyrolysis, in particular, plays a vital role in UCG. We herein investigated the pyrolysis behavior of lump lignite from Inner Mongolia, China, and investigated the influence of pyrolysis on the swelling behavior of the lump lignite. The samples (50 × 40 × 40 mm 3 ) were studied at a heating rate of 3 °C/min. The resulting chars were analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy. In addition, the composition of the pyrolysis gas released from lump lignite was compared with that released from particle lignite (particle diameter = 1 mm). The results showed that obvious swelling between 100 and 600 °C, followed by subtle swelling events between 600 and 900 °C. The concentrations of H 2 and CO gases in lump lignite were higher than those in particle lignite when exposed to elevated temperatures, and the main functional groups disappeared at high temperatures due to thermal cracking. Consequently, pyrolysis occurring in the gasification channel converted the coal around the channel into a highly porous char whose permeability aided the transport of gasification agents and product gases in coal seam. [ABSTRACT FROM AUTHOR]

Hydrocarbon pyrolysis concerns many different fields (petroleum geochemistry, refinery, fuel thermal stability, pyrocarbon deposition, etc.). It is therefore studied in a wide variety of temperature–pressure experimental conditions, which strongly affect the chemistry of hydrocarbons cracking. An experimental study of the pyrolysis of n -octane has been performed at very low reactant concentration (1 mbar diluted in inert gas − total pressure 1500 mbar − molar fraction 0.07%) in a closed reactor, at temperatures ranging between 350 °C and 450 °C, and reaction time from 1 h to 70 h. The major products of the reaction are 1-alkenes (C 2 H 4 to C 7 H 14 ), methane and ethane; other alkanes (C 3 H 8 to C 6 H 14 ) are minor products. At 450 °C and 4 h, the conversion is close to 9% and we observe, in terms of molar fractions: C 2 H 4 > C 3 H 6 ≈ CH 4 > C 4 H 8 > C 5 H 10 > C 6 H 12 ≈ C 2 H 6 > C 7 H 14 These experimental results are very different from those of the thermal decomposition of n -alkanes at the same low temperature but at high pressure. In particular, the cracking stoichiometric equations (for example: C 8 H 18 = C 6 H 14 + C 2 H 4 ) are not observed since alkanes (except methane and ethane) are in very low quantities. This can be explained by the very low concentration of reactant which limits the bimolecular reactions. In our conditions, the radicals decompose several times by beta-scissions of CC bonds when it is possible (unimolecular reaction), rather than react by H-transfers (metathesis) with the reactant (bimolecular reaction) which produce alkanes. A detailed free radical mechanism (184 reactions, 16 molecules and 18 radicals— mechanism available as Supplementary material) allows modeling the experimental results. [ABSTRACT FROM AUTHOR]

We studied the pyrolysis of n -butylcyclohexane at high pressure (100 bar) in a gold sealed tube reactor between 300 and 425 °C. The conversion obtained was between 3% and 99%. Pyrolysis led to 3 main chemical classes of products: (a) n -alkanes (methane, ethane, propane and butane), (b) naphthenes (cyclohexane, methylcyclohexane, methylcyclopentane) and (c) alkylbenzenes (benzene, toluene, butylbenzene). This distribution of major products does not suggest any ring opening during thermal cracking, but rather breaking of alkyl side chains along with aromatization. The early production of butylbenzene at low conversion indicates that aromatization occurred first. We proposed pathways mainly based on free-radical reactions to account for the formation of major pyrolysis products i.e., propane, cyclohexane, methylcyclopentane and butylbenzene. Experimental data enabled us to determine apparent global kinetic parameters under the assumption of a first-order rate: frequency factor A = 6.7 × 10 16 s −1 and activation energy E a = 69 kcal/mol. We made several comparisons between n -alkanes, aromatic compounds and naphthenes, to observe the relative thermal stability of different classes and the influence of the length of an alkyl side chain. Data from the literature at high pressure or simulations from validated kinetic models were used. For the same carbon number, thermal stabilities of naphthene and n -alkane are similar, whereas the equivalent aromatic compound is less stable. This observation only seems valid for long alkyl side chains, as methylated compounds are much more stable than other alkylated ones, whether these are aromatic or naphthenic. [ABSTRACT FROM AUTHOR]

The hydrocracking of thermal cracking waxes obtained from pyrolysis of polyolefin at 360°C for 120 min has been studied using Ni-loaded molecular sieves catalysts. According to XRD, TPR, and BET data, the presence of nickel oxide did not seem to damage the crystalline framework of the catalytic supports. Hydrocracking experiments were carried out in a stirred autoclave reactor at 300°C for 120 min under 2.0 MPa of hydrogen. The results suggested the existence of a balance between the acid and metal function over bifunctional catalysts, which affects hydrogenation and hydroisomerization of thermal cracking waxes. Hydrocracking reactions took place extensively over mixture of Ni/HBeta and ZSM-5, leading toward higher fractions of gases (30.2%) and diesel (23.5%). The higher fractions of gasoline (33.5%) and lube base oil (19.0%) were obtained over mixture of Ni/HSAPO-11 and ZSM-5. In contrast, hydrocracking reaction occurred in a lower extent over mixture of Ni/NMCM-41 and ZSM-5, which produces lube base oil with lower pour point (–10°C), gasoline and diesel with lower bromine numbers (1.1 and 0.8 g Br2/100 g sample). The viscosity index of lube base oil was in the range of 131–171 over all three mixed catalysts. [ABSTRACT FROM AUTHOR]

A typical petroleum refinery makes use of vacuum gas oil by cracking the large molecular weight compounds into light fuel hydrocarbons. For various types of fast pyrolysis bio-oil, successful analogous methods for processing heavy fractions could expedite integration into a petroleum refinery for fuel production. This paper investigated the applicability of bio-oil distillation residues (i.e., ‘bottoms’) toward end-use and/or post-processing through the use of various physical and chemical characterization methods, including FTIR, NMR and their decomposition in a micropyrolyzer (Py–GC–MS). We compared distillate bottoms from both the recently developed tail-gas reactive pyrolysis (TGRP) and traditional pyrolysis bio-oils, emanating from switchgrass and horse manure feedstocks. Based on the FTIR and NMR measurements, we found the traditional bio-oil bottoms to contain more reactive functional groups, whereas TGRP bottoms are highly aromatic and exhibit a lack of functional groups. Manure-based bottoms consistently contained more aliphatic carbons than those of switchgrass origin. However, irrespective of the origin of the feedstock, all bottoms samples possessed high HHVs making them suitable for solid fuel application, such as direct combustion (30 MJ/kg for traditional bio-oil bottoms; 37 MJ/kg for TGRP bottoms). A preliminary evaluation using Py–GC–MS to test their suitability for use in refinery cracking processes revealed that the TGRP-based bottoms all produced significant yields of pyrolyzate (20–50%), with nearly all detected compounds comprising alkyl benzenes and alkyl phenols. However, the manure-based TGRP bottoms produced a higher proportion of C 8 –C 18 paraffin compounds. [ABSTRACT FROM AUTHOR]

This work present a novel primary method, for tar reduction in downdraft gasification. The principle of this new technology is to change the fluid dynamic behaviour of the mixture, formed by pyrolysis product and gasification agent in combustion zone; allowing a homogeneous temperature distribution in radial direction in this reaction zone. To achieve the change in the fluid dynamic behaviour of the mixture; the entry of gasification agent to combustion zone is oriented by means of wall nozzles in order to form a swirl flow. This modification in combination with the extension of the reduction zone, will allow, to increases the efficiency of the tar thermal cracking inside the gasifier and the extension of the Boudouard reactions. Consequently, the quantity of tar passing through the combustion zone without cracking and the concentration of tar in the final gas, decrease significantly in relation with the common value obtained for this type of reactor, without affecting significantly the heating value of the producer gas. In this work is presented a new design for 15 kW downdraft gasification reactor, with this technology implemented, the tar content obtained in the experiments never overcome 10 mg/Nm 3 , with a lower heating value of 3.97 MJ/Nm 3 . [ABSTRACT FROM AUTHOR]

Naphtha is an important feedstock for the petrochemical industry and accurate measurement of its detailed composition is essential for the optimization of pyrolysis processes. In the present work, the suitability of using near infrared (NIR) for the determination of 38 parameters used to characterize naphtha was evaluated: pooled composition (PIONA); specific composition groups (C3 paraffins; C4–C12 n-paraffins; C4–C12 iso-paraffins; C5–C7 + naphthenics; C8–C10 aromatics; C4–C6 olefins) and individual components (toluene, benzene, iso-pentane, cyclopentane, methyl cyclopentane; cyclohexane, xylenes, 1,3 butadiene and isoprene). Besides the usual comparison against reference methods, NIR predictions were also evaluated for their ultimate use in determining the coil outlet temperature (COT) for process control. 28 models for the naphtha parameters presented root mean square error (RMSEP) values lower or close to the reproducibility of the reference method and exhibited satisfactory correlation values ( r 2 ) when compared with r 2 max . Among the ten remaining parameters, two (1,3 butadiene and isoprene) presented very low concentrations and it was not possible to obtain a suitable model. Eight parameters had RMSEP values higher than the intralaboratory reproducibility and/or r 2 values lower than expected. Despite this, the complete naphtha composition obtained from NIR prediction was demonstrated to be quite suitable for COT simulation, providing accurate COT values compared to the values estimated from the reference method. [ABSTRACT FROM AUTHOR]

Pyrolysis of bagasse followed by nano-catalytic cracking of tar was carried out at atmospheric pressure using a dual bed micro reactor. The first bed was used for pyrolysis and the second bed was used for cracking of tar. Bimetallic 12%Ni6%Fe/γ-Al2O3 nano catalysts were prepared using microemulsion technique with water-to-surfactant ratios of 1-5. The catalysts were characterized by ICP-AES, BET, XRD, H2 chemisorption, TPR and TEM techniques and their activity and selectivity in bagasse pyrolysis were assessed. The physico-chemical properties and performance of the nano catalysts were compared with the catalyst prepared by impregnation method. The TEM images showed that small metal nanoparticles are dispersed on the surface of support in the range of 3-5nm. Using microemulsion technique with water to surfactant ratio of 1 decreased the average metal particle sizes to 3.7nm. The percentage reduction and percentage dispersion are almost doubled. A gas richer in hydrogen (15.3mol.%) and carbon monoxide (45.7mol.%) and poorer in carbon dioxide (31.6mol.%) and hydrocarbons were produced through microemulsion synthesized nano-catalysts. The proposed catalyst prepared with microemulsion (water-to-surfactant ratios of 1) increased the gas yield from 0.397 to 0.758 (m3/kg) and decreased the tar yield from 0.445 to 0.237 (g/g of biomass) compared to noncatalytic process while the heating value of the product gas remained almost constant (10-11MJ/m3). [ABSTRACT FROM AUTHOR]

Pyrolysis of Bulgarian oil shale was studied by using a diamond anvil cell, which allows one to observe directly the conversion of organic matter to mobile oily liquid, solid residue and gas. This method gives the possibility to detect very precisely the temperatures of kerogen transformation during pyrolysis. It was observed that most of the gaseous products were generated later than oily liquids, most probably by cracking processes of liquid products. Due to the strong connection between mineral and organic matter, the generation of liquids and gases from oil shale occurred at higher temperature. Light intensity measurements were used to follow quantitatively the rate of reaction. [ABSTRACT FROM AUTHOR]

Highlights: [•] The whole formation process of shale oil might be divided into four stages. [•] Higher ash/shale mass ratio intensified the cracking and coking of shale oil. [•] Ash/shale ratio of 1:2 was recommended for oil shale fluidized bed retort with fine oil-shale ash as solid heat carrier. [Copyright &y& Elsevier]

Highlights: [•] Coal, extracted coal and bitumen enriched coal were pyrolyzed. [•] Yields and compositions of bitumen, liquid n-alkanes and gases were determined. [•] Kinetic parameters for the generation and cracking of gas hydrocarbons were derived. [Copyright &y& Elsevier]

A steam cracking furnace plays animportant role in the naphthapyrolysis process that produces ethylene and propylene. These twoproducts are the key monomers in the petrochemical industry. Thisarticle investigates the multiobjective operation optimization ofthe naphtha pyrolysis process to maximize the yields of ethylene andpropylene. To solve this problem efficiently, multiobjective paralleldifferential evolution with competitive evolution strategies (MOPDE-CES)is employed. In MOPDE-CES, the population is divided into four parts,each part having its own evolution strategy. During evolution, thefour parts of the population compete with each other to survive andevolve. At the same time, they share search information with eachother by communicating with an external archive that stores the obtainednondominated solutions. The MOPDE-CES approach is compared to otherpowerful multiobjective algorithms, and the computational resultsshow that MOPDE-CES is superior based on benchmarking and practicalproblems. In addition, the computational results of MOPDE-CES indicatethat the operation of an ethylene plant can be improved by increasingthe yields of ethylene and propylene. [ABSTRACT FROM AUTHOR]

Mesopore-modified mordenite zeolitic materials with different Si/Al ratios have been prepared and tested in the biomass pyrolysis and catalytic cracking of vacuum gasoil. Alkaline treatment was carried out to generate mesoporosity. Severity of alkaline treatment was found to be of paramount importance to tune the generated mesoporosity, while it significantly affected the crystallinity of treated mordenites. It was moreover observed that the alkaline treatment selectively extracted Si decreasing the Si/Al ratio of treated samples. Catalytic activity of parent and alkaline treated mordenites was studied in the pyrolysis of biomass. All zeolitic based materials produced less amounts of bio-oil but of better quality (lowering the oxygen content from ∼40% to as much as 21%) as compared to the non-catalytic pyrolysis experiments. On the other hand, it was found that the combination of mesopore formation and high surface area after alkaline treatment of the mordenite with a high Si/Al ratio resulted in the enhancement of its catalytic activity, despite the reduction of its acidity. The increment of the decarboxylation and dehydration reactions, combined with a reduction of carbon deposition on the catalyst, resulted in a remarkable decrease in the oxygen content in the organic fraction and therefore, resulted in a superior quality liquid product. Alkaline treated mordenites were additionally acid treated targeting dealumination and removal of the extra framework debris, thus generating mesopore-modified mordenite samples with stronger acid sites and higher total acidity, as candidate catalysts for catalytic cracking of vacuum gasoil. Desilicated and especially desilicated and dealuminated mordenites exhibited the highest activity and selectivity towards LCO with the best olefinicity in gases and higher bottoms conversion. Therefore, an optimized desilicated–dealuminated mordenite additive could be an interesting candidate as a component of the FCC catalyst for a high LCO yield. [ABSTRACT FROM AUTHOR]

Abstract: Thermal pyrolysis of plastic wastes in tubular reactor has been studied with Direct Computer Mapping based simulation methodology, combined with genetic algorithm. Degradation process was carried out in laboratory and pilot scale tubular reactor. The investigated pyrolysis temperature range was 465–545°C, and raw material feeding rate was between 6 and 20g/min. A dynamic simulation model has been developed based on a four-step degradation scheme, considering four cracking product fractions (gas, naphtha, middle distillate and heavy oil) and their hydrocarbon composition (paraffin, olefin and aromatic). A collaborating genetic algorithm was used for the identification of kinetic and stoichiometric model parameters. Having analyzed the identification results we concluded that some of the stoichiometric parameters, moreover all of the kinetic parameters and vapour/liquid phase ratios were independent from the reaction parameters, however they depend on the quality of raw material. The temperature and feeding rate dependency of the model were considered by two calculated parameters (pLiq, pAro). According to the investigations, the rate determining factor of the degradation process is the effectively utilized enthalpy resulting from the heat transfer through the wall of the equipment. The simplified dynamic simulation model can support the scale-up procedure of the pyrolysis technology. [Copyright &y& Elsevier]

Abstract: This paper describes the experience gained from the integration of symbolic modelling within an existing equation-based flowsheet package, SPYRO® Suite 7. A demand for more flexibility led to the integration of a symbolic model definition module into the existing program. We elaborate on our motivations and choices made to our decision for the gPROMS language. The existing program is described, and in some detail the functionalities to minimise the modelling errors and to enhance the detection of them. The gPROMS language itself, the evolution of it and the selected subset are described. Additionally, new attributes of the language are described: spline construction, intermediate graphical results, and definition of a large number of simulations/optimisations. The symbolic model definition module is demonstrated on the determination of an attainable region and the thermal cracking of ethane. The symbolic modelling module proved to be cost effective and improved the quality of the main engine. [Copyright &y& Elsevier]

To maximize oil yields in the fast pyrolysis of biomass it is generally accepted that vapors need to be rapidly quenched. The influence of the heterogeneous and homogeneous vapor-phase reactions on yields and oil composition were studied using a fluidized-bed reactor. Even high concentrations of mineral low char (till 55 vol %) appeared not to be catalytically active. However, the presence of minerals, either in biomass or added, does influence the yields, especially by the occurrence of vapor-phase charring/polymerization reactions. Contradictory, in the absence of minerals, homogeneous vapor-phase cracking reactions were dominant over polymerization/charring reactions (400-550°C, 1-15 s). With increasing vapor residence time, the oil yield reached an asymptotic value, which decreased with temperature. At a vapor temperature of 400°C no decrease in oil yield was observed, but dedicated analysis showed that homogeneous vapor to vapor reactions had occurred. © 2011 American Institute of Chemical Engineers AIChE J, 2012 [ABSTRACT FROM AUTHOR]

Modeling of complex reaction systems is necessary in the design, analysis, and optimization of many technologically important processes such as pyrolysis, steam cracking, coking, partial oxidation, and combustion. The complexity in kinetic modeling of all these processes is introduced both by the feed, which is a hydrocarbon mixture, and the high reactivity of radical intermediates. Recent advances in automated mechanism generation tools, although capable of establishing the complex reaction network, pose a big challenge of assigning rate parameters for all the reactions or devising appropriate estimation rules for all reaction classes in the network. The kinetics of free radical reactions dictates the chemistry of technologically important thermal processes. Intermolecular hydrogen abstraction by radicals is one of the dominant reaction types and constitutes a major part (often >50%) in any thermal reaction network owing to their profound effect on product distribution. While abstraction reactions by H atoms (and to some extent by methyl radicals) have been studied extensively in the past, the abstraction kinetics by vinyl radical is less explored even though vinyl radicals play an important role in molecular weight growth chemistry and in predicting acetylene concentrations in pyrolysis and fuel-rich hydrocarbon flames. This study presents the hierarchical tree structure for intermolecular hydrogen abstraction by vinyl radicals from {C/H} molecules and provides generic rate rules that account for most of the variation in CH bond energy in the family of aliphatic, aromatic, naphthenic, olefinic, and aromatic naphtheno hydrocarbons. Reaction classes developed in this work are still dictated by immediate neighbors within the spirit of group additivity, although some efforts were made to access the effect of non-next neighbors on generic rate parameters. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 327-349, 2012 [ABSTRACT FROM AUTHOR]

Thermal cracking of n-decane and n-decane in the presence of several fuel additives are studiedinorder to improve the rate of thermal cracking by using reactive moleculardynamics (MD) simulations employing the ReaxFF reactive force field.From MD simulations, we find the initiation mechanisms of pyrolysisof n-decane are mainly through two pathways: (1)the cleavage of a C–C bond to form smaller hydrocarbon radicals,and (2) the dehydrogenation reaction to form an H radical and thecorresponding decyl radical. Another pathway is the H-abstractionreactions by small radicals including H, CH3, and C2H5. The basic reaction mechanisms are in good agreementwith existing chemical kinetic models of thermal decomposition of n-decane. Quantum mechanical calculations of reaction enthalpiesdemonstrate that the H-abstraction channel is easier compared withthe direct C–C or C–H bond-breaking in n-decane. The thermal cracking of n-decane with severaladditives is further investigated. ReaxFF MD simulations lead to reasonableArrhenius parameters compared with experimental results based on first-orderkinetic analysis. The different chemical structures of the fuel additivesgreatly affect the apparent activation energy and pre-exponentialfactors. The presence of diethyl ether (DEE), methyl tert-butyl ether (MTBE), 1-nitropropane (NP), 3,6,9-triethyl-3,6,9-trimethyl-1,2,4,5,7,8-hexaoxonane(TEMPO), triethylamine (TEA), and diacetonediperodixe (DADP) exhibitremarkable promoting effect on the thermal cracking rates, comparedwith that of pure n-decane, in the following order:NP > TEMPO > DADP > DEE (∼MTBE) > TEA, which coincideswithexperimental results. These results demonstrate that reactive MD simulationscan be used to screen for fuel additives and provide useful informationfor more comprehensive chemical kinetic model studies at the molecularlevel. [ABSTRACT FROM AUTHOR]

Abstract: The gas generative potential of organic matter is one key parameter for the calculation of total gas in place (GIP) when evaluating thermogenic shale gas plays. Having first demonstrated that late gas-forming structures are present in coals of anthracite rank (>2% R 0) we go on to examine other rocks at the immature stage of maturity and report on how to recognise which might generate significant amounts of late dry gas at geologic temperatures well in excess of 200 °C in the zone of metagenesis (R 0 > 2.0%), i.e. subsequent to primary and secondary gas generation by thermal cracking of kerogen or retained oil. Such a distinction could clearly be of major value when assessing risks and pinning down “sweet spots”. A large selection (51 samples) of source rocks, i.e. shales and coals, stemming from different depositional environments and containing various types of organic matter which contribute to the formation of petroleum in putative gas shales were investigated using open- and closed-system pyrolysis methods for the characterisation of kerogen type, molecular structure, and late gas generative behaviour. A novel, rapid closed-system pyrolysis method, which consists of heating crushed whole rock samples in MSSV-tubes from 200 °C to 2 different end temperatures (560 °C; 700 °C) at 2 °C/min, provides the basis for a newly proposed approach to discriminate between source rocks with low, high, or intermediate late gas potential. It is noteworthy that late gas potential goes largely unnoticed when only open-system pyrolysis screening-methods are used. High late gas potentials seem to be mainly associated with heterogeneous admixtures or structures in terrestrially influenced, in some cases marine, Type III and Type II/III coals and shales. Aromatic and/or phenolic signatures are therefore indicative of the possible presence of elevated late gas potential at high maturities. High temperature methane was calculated to potentially contribute an additional 10–40 mg/g TOC, which would equal up to 30% of the total initial primary petroleum potential in many cases. Low late gas potentials are associated with homogeneous, paraffinic organic matter of aquatic lacustrine and marine origin. Source rocks exhibiting intermediate late gas potentials might generate up to 20 mg/g TOC late dry gas and seem to be associated with heterogeneous marine source rocks containing algal or bacterial derived precursor structures of high aromaticity, or with aquatic organic matter containing only minor amounts of aromatic/phenolic higher land plant material. [Copyright &y& Elsevier]

Abstract: Several models have been reported in the literature for thermal cracking of petroleum residues. Most of these models are either highly empirical or first principles based models requiring detailed analysis of the feedstock. The present paper is an attempt to put forward a critical appraisal of various published models. The authors have also generated the experimental data on a batch reactor for different feedstocks, and multi-lump parameter models (reported elsewhere) have been developed with the generated data. Three different models for prediction of experimental yields in terms of gas and distillate fractions (i.e. kerosene, LGO and VGO) have been critically evaluated in the light of experimental data. [Copyright &y& Elsevier]

Abstract: Vegetable oils (in Europe particularly rapeseed) are the favoured raw material for production of methyl esters to be used as biodiesel. This paper discloses a possibility of their alternative utilization as crude oil substitute via vegetable oil steam cracking to produce short alkenes to be used in polyolefins production industry. During thermal decomposition under conditions matching those of gas-oil steam cracking (short residence time, temperature over 800°C) vegetable oils form similar products as traditional crude-oil-based feedstocks. The yields of major pyrolysis products of various vegetable oils were determined using the apparatus employed previously to laboratory research of hydrocarbon pyrolysis and they were compared to yields obtained by cracking traditional feedstocks. Also the effects of hydrocarbon chain length and saturation of acyls forming the oils were analyzed in detail. The possibilities of processing vegetable oils by co-cracking in mixture with crude oil feedstocks are discussed and supported by experimental data. [Copyright &y& Elsevier]

Catalytic upgrading of pyrolysis vapors derived from oak was carried out using a fixed-bed catalytic column at 425 °C. The vapors were drawn by splitting a fraction from the full stream of vapors produced at 500 °C in a 5 kg/h bench-scale fast pyrolysis reactor system downstream from the cyclone separator. The placement of the fixed-bed column was varied within the condenser train to determine the effect of temperature, residual water, solids, and oxygenated components of the approach vapor stream on the upgraded product quality. The upgraded liquid was collected by immediate contact with a dry ice acetone bath, complimented by a secondary collection system comprised of a methanol spray condenser. Quantitative gas chromatography/mass spectroscopy (GC/MS) analysis of the recovered liquid showed a substantial decrease of oxygen-containing species with a significant increase in carbon-rich (≥C6) aromatic hydrocarbons. The extent of deoxygenation was location-specific and dependent upon temperature and the relative concentrations of water, oxygenates, and residual solids in the approach vapor. The study provides the engineering practicality to catalytic vapor upgrading and offers the necessary data for the design and optimization of a full-stream upgrading of pyrolysis oils via in situ vapor cracking. [ABSTRACT FROM AUTHOR]

Spouted beds are used in chemical vapor deposition as they provide good solid mixing, thereby enhancing high mass and heat transfer rates. In the present study, investigations on the kinetics of a coating process by chemical vapor deposition were carried out in a spouted-bed reactor. Pyrolytic carbon coatings were studied by thermal cracking of acetylene mixed with carrier gas argon at 1350 °C. A theoretical model was proposed based on the mass balance of the precursor in the spout and annulus zones at isothermal condition, and the model equations were solved using MATLAB (version 7.1) software. The effect of the operating gas velocity, initial static bed height, and acetylene concentration on the coating rate was examined experimentally and also by simulation results. The simulated results agreed well with the experimental results. Model equations used for simulation were utilized to evaluate the reaction rate constant and radial gas diffusion coefficient and then to study the effect of spout diameter, operating gas velocity, and precursor concentration on the overall conversion of the precursor. [ABSTRACT FROM AUTHOR]

Bio-oil has attracted considerable interest as a promising renewable energy resource because it can be utilized as a feedstock in integrated bio-refineries for the production of highly valuable chemicals and next-generation hydrocarbon fuels. However, it is necessary to improve the bio-oil quality before it can be fed to bio-refineries. Currently, catalytic vapor cracking seems a more attractive process than catalytic upgrading technologies, such as hydrotreating and esterification, in order to improve the bio-oil quality. This review presents a summary of recent research and the state of art technology for the catalytic vapor cracking of bio-oil, focusing on the catalysts applied, upgrading methods and reaction mechanisms. [ABSTRACT FROM AUTHOR]

Polyethylene terephthalate (PET) is a widely used thermoplastic. PET residues represent on average 7.6 wt% of the different polymer wastes in Europe. Pyrolysis of these wastes is attracting increasing interest, and PET is a potential candidate for this thermal process. The paper measures and discusses the kinetics of the pyrolysis reaction in terms of the reaction rate constants as determined by dynamic thermogravimetric analysis, with special emphasis on the required heating rate to obtain relevant results. The product yields and compositions are also determined. Gaseous products represent 16-18 wt%. The amounts of condensables and carbonaceous residue are a function of the operating mode, with slow pyrolysis producing up to 24 wt% of carbonaceous residue. Major condensable components are benzoic acid, monovinyl terephthalate, divinyl terephthalate, vinyl benzoate, and benzene. The present paper complements previous literature findings by (1) the study of the influence of the heating rate on the reaction kinetics in dynamic pyrolysis tests, (2) the isothermal investigation in a fluidized bed reactor to pyrolyze PET, and (3) the assessment of upgrading and recovery of the products. The paper concludes with a proposed reactor recommendation for PET pyrolysis, in either the bubbling or circulating fluidized bed operating mode. [ABSTRACT FROM AUTHOR]

Abstract: We study one-dimensional flows, when air is injected into a porous medium filled with inert gas, medium or high viscosity oil and water, giving rise to a combustion wave in a process known as high-temperature oxidation (HTO). In the oil we distinguish three pseudo-components: asphaltenes, medium and light oil. At high temperatures, the heaviest components (“precoke”) are converted to coke, which undergoes combustion. Medium oil components are cracked at intermediate temperatures releasing gaseous oil. Light oil components and water are vaporized. The oxidation rate of gaseous oil components is negligible. Combustion regimes are described in the form of a sequence of waves. We develop a simple mathematical pathway based on Zeldovich’s approach to provide analytical formulae for parameters in these waves. It is shown that there is a combustion regime in which either coke or oxygen are partially consumed in the combustion as well as a regime in which both are consumed completely. Each of the regimes can be subdivided in two regimes, where the reaction is either trailing or leading with respect to the thermal wave. Explicit conditions for each combustion regime are given. The structure of the oil cracking layer is investigated. Stability of the solutions is studied. We analyse our formulae for typical in situ combustion data and compare the results with numerical simulations. [Copyright &y& Elsevier]

A new concept of reactora prototype of transported-loop reactor that reduces residence time for the cracking of a light naphtha streamenhances commercial, low-value, light streams with an alternative process to applying these fractions to light olefins (ethylene and propylene). In particular, a prototype of a transported-loop reactor was developed to reduce the resistance time in the cracking of a light naphtha stream to produce olefins. In particular, a prototype of a transported-loop reactor has been developed to reduce resistance time in the cracking of a light naphtha stream to produce olefins. It is currently used to study the gas−solid fluid-dynamic. The novel device includes a uniflow-type reactor and a partial gasification downer riser circulating reactor. The novelty lies in converting the light naphtha at a very high temperature and ultrashort residence time by contacting a hot solid with the naphtha to immediately separate the olefins to avoid further reactions. The solid is then partially gasified to provide autothermal operation of the reactors. The design of the equipment provides information about the gas/solid contact to develop several prototypes of the pyrolysis and the carbon gasification reactor. The cold model will derive suitable hydrodynamic relationships and performance constraints for high solid loading not available in the literature. The main result obtained is the need to provide an initial high solid contact to ensure the heat transfer and then proceed to separate the gas and solid. The other result is the effect of the hydrocyclone in the clustering behavior of the circulation reactor. Knowledge of the fluid dynamic in both reactors and kinetic information already developed will facilitate design and scale-up of a new process for cracked naphtha valorization. [ABSTRACT FROM AUTHOR]

Fast pyrolysis of poplar wood followed with catalytic cracking of the pyrolysis vapors was performed using analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The catalysts applied in this study were nano MgO, CaO, TiO2, Fe2O3, NiO and ZnO. These catalysts displayed different catalytic capabilities towards the pyrolytic products. The catalysis by CaO significantly reduced the levels of phenols and anhydrosugars, and eliminated the acids, while it increased the formation of cyclopentanones, hydrocarbons and several light compounds. ZnO was a mild catalyst, as it only slightly altered the pyrolytic products. The other four catalysts all decreased the linear aldehydes dramatically, while the increased the ketones and cyclopentanones. They also reduced the anhydrosugars, except for NiO. Moreover, the catalysis by Fe2O3 resulted in the formation of various hydrocarbons. However, none of these catalysts except CaO were able to greatly reduce the acids. [ABSTRACT FROM AUTHOR]