Series Of Pyrolysis Experiments Research Articles

Pyrolysis of cashew nut shells-focus on extractives

Cashew nut shells (CNS), as non-edible agricultural residues produced by cashew nut shelling units, are largely abundant in West Africa. They present a strong potential for energy production although the presence of specific extractives known collectively as cashew nut shell liquid (CNSL) is problematic. These extractives can account for up to 40 % of the mass of the shells and are mainly composed of anacardic acids, cardanols and cardols (ACC). The objective of this work was to study the influence of ACC constituents on the pyrolysis of CNS. To this end, an exhaustive characterization of CNS was performed, followed by a series of pyrolysis experiments on CNS, extractives and solid residues. Thermogravimetric analyses revealed intermolecular interactions between the lignocellulosic solid matrix and the extractives of CNS. Experiments carried out in a fixed bed reactor enabled determination of pyrolysis products composition. Only cardanols were present in both CNS and ACC pyrolysis condensates. The degradation of anacardic acids during ACC pyrolysis at 400 °C was investigated and showed that 45 % of anacardic acids produce cardanols as end products, whereas the remaining anacardic acids form thermal cracking products (char, gas and condensates). The distribution of the end products of CNS pyrolysis is illustrated in the graphical abstract.

A comparison of hydrocarbon generation and expulsion in carbonate and argillaceous source rocks using semi-open pyrolysis experiments

To investigate the hydrocarbon generation and expulsion efficiency from carbonate and argillaceous source rocks, a series of pyrolysis experiments were conducted on two representative samples with Type II kerogen in a semi-open simulation system. The shale sample was obtained from the Upper Cretaceous Second White Speckled Shale Formation, while the carbonate sample was collected from the Middle Devonian Brightholme Member of the Winnipegosis Formation, both from the Western Canada Sedimentary Basin. The results show that the carbonate has a higher hydrocarbon generation capacity than the shale. During the pyrolysis, the expelled hydrocarbons from the carbonate were about 100–200 mg/g TOC higher than the hydrogen index reduction, while the amount of expelled hydrocarbons from the shale was generally lower than the hydrogen index reduction. The peak oil generation from the carbonate occurred earlier than that from the shale, but the oil expulsion efficiency was lower. However, a larger quantity of unexpelled oil retained in the carbonate was conducive to later oil expulsion, more hydrocarbon gas generation, and slightly higher gas expulsion efficiency than for the shale. Although hydrocarbon gases generated from both sources share similar evolution trends with heating, the relative proportions of CO2 and methane differ significantly between the two lithologies, with much higher abundance of CO2 in shale pyrolysate. The carbon loss during maturation of the two source rocks is very similar during the oil generation window, but the carbon loss trend was reversed in shale after the onset of gas generation, due to the conversion of some bitumen to pyrobitumen. Conversely, carbon loss continued in the carbonate to a higher maturity stage. This difference can be attributed to the occurrence of different organic matter types in the carbonate, including dispersed organic matter, aggregated organic matter, crystal-enclosed organic matter, and inclusion-hosted organic matter. These various organic matter types contribute to continuous oil and gas expulsion over a much wider maturity range than shale. Although the two samples chosen for this study do not encompass the entire range of carbonate and shale formations, the established hydrocarbon generation and expulsion models and evaluation criteria for argillaceous source rocks may not be directly applicable to carbonates, particularly at high maturity stages. These valuable insights have significant implications for oil and gas exploration in diverse geological settings. The research highlights the tendency of carbonate source rocks to experience higher organic carbon loss during maturation compared to argillaceous rocks. This suggests that certain low-TOC, highly mature carbonate source rocks can potentially serve as effective hydrocarbon source rocks if successful oil expulsion occurs. These findings underscore the need to take into account the distinctive characteristics of carbonate source rocks when developing strategies for hydrocarbon exploration and production.

A comprehensive study on the impacts of rock fabric on hydrocarbon generation and pore structure evolution of shale under semi-confined condition

Semi-confined pyrolysis experiments were performed on core and powdered samples taken from type-II lacustrine mudstone to investigate the effects of sample rock fabrics on hydrocarbon generation and porosity changes when shale is subjected to pyrolysis. The generated hydrocarbons were analysed by organic geochemical methods to reflect differences in constituents and carbon isotopes. Gas (N2 and CO2) adsorption tests were applied to solid residues to characterize the formation and development of pores after the two series of pyrolysis experiments. Simple calculations indicate that hydrocarbons prefer to expulse as intact rock fabric is destroyed. Secondary cracking gas accounted for approximately 23–30% and 28–49% of all gaseous hydrocarbons in the powdered and core samples, respectively. Side reactions, such as mineral catalytic and recombination reactions, prevailed during the semi-closed pyrolysis of powdered sample at 300–500 °C, causing generated C3+ hydrocarbon yields to be lower than those of the core sample. Additionally, gaseous hydrocarbons generated from the powdered sample were characterized by more positive δ13C and higher iso-/n-C4,5 and C1/C1-5 values. Side reactions ceased at 500–550 °C, and corresponding ratios tended to equalize. For the powdered samples, a higher expulsive ratio of hydrocarbons led to better pore development, the mesopore volume increased with increasing temperatures, and micropore volume decreased above 450 °C. Comparatively, the mesopore volume decreased above 450 °C for the core sample, and the micropore volume decreased above 500 °C. These results are helpful for revealing the genetic characteristics of shale gas and for understanding the origins of organic-hosted pores of the Cambrian Niutitang shale in southern China. The study suggests that samples with intact rock fabric should be used in future laboratory pyrolysis tests to generate results that better reflect natural conditions.

The effect of heating rate, particle size and gas flow on the yield of charcoal during the pyrolysis of radiata pine wood

Charcoal derived from sustainable grown wood is a potential source of fuel and reductant for iron and steel making and a potential way to decrease the net CO2 emissions from the steelmaking industry. However a modern charcoal making process is likely to be required to supply the iron and steel industry with the required amount of charcoal to make significant difference to greenhouse gas emissions. The design of such a process requires fundamental knowledge on the effect of process variables on charcoal formation and yield during pyrolysis.The effect of biomass heating rate, purging gas flow and particle size on the yield of charcoal from pine wood was quantified in a series of pyrolysis experiments using a thermo-gravimetric apparatus. Temperature-time curves obtained during the heating of biomass showed the pyrolysis reactions became exothermic at about 350 °C. Increasing the flow of inert carrier gas through the biomass sample resulted in a decrease in charcoal yield and a faster rate of biomass decomposition. At zero gas flow the charcoal yield is independent of particle size. As gas flow through the sample is increased the yield of charcoal is increasingly dependent on increasing particle size.Increasing the wood heating rate from 0.11 to 10 °C/min, resulted in decreased charcoal yield. The period of fast biomass decomposition shifted to higher temperatures and the start of decomposition occurred at higher temperatures. These results indicate that low temperature reactions of charcoal formation are favoured by low heating rates and the initial charcoal acts as a catalyst for primary biomass decomposition. Lower heating rates are also associated with increased retention of pyrolysis vapours in the biomass which results is increased production of secondary charcoal and increased charcoal yield.

Transformation of alkali and alkaline earth metals in Zhundong coal during pyrolysis in an entrained flow bed reactor

The transformation of alkali and alkaline earth metals (AAEMs) in Zhundong coal during pyrolysis in an entrained flow bed reactor was elucidated, which provides theoretical guidance for selecting suitable processing technology for Zhundong coal. A typical coal was sampled, and a series of pyrolysis experiments with gradual and small increments in temperature was performed using an entrained flow bed reactor. Chars from pyrolysis at different temperatures were characterised using an improved sequential extraction method, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), and field emission scanning electron microscopy coupled with energy dispersive spectroscopy (FESEM-EDS) to determine the occurrence modes, chemical composition, and the distribution of AAEMs on the surface of coal char as a function of the change in pyrolysis temperature. In addition, thermodynamic “FactSage” software was used to simulate the evolution of AAEM species during the entire pyrolysis process. Thus, a transformation mechanism of AAEMs in Zhundong coal during pyrolysis is proposed. The results show that as the pyrolysis temperature increases, the contents of water-soluble and exchangeable sodium in coal char decrease, and their release results in a decrease in total sodium content. The insoluble potassium decomposes slightly at high temperatures, and the change in the total potassium content is not obvious. HCl-soluble magnesium and calcium species also decompose at high temperatures and then react with SiO2 and/or Al2O3 to form insoluble silicates or aluminosilicates. As a result, the surface of the coal char becomes enriched in insoluble magnesium and calcium. The variation trend of AAEMs obtained by the FactSage simulation is generally consistent with the experimental results. Upon the process of pyrolysis, the surface of the char sample becomes rough and is covered by cracks and holes. Consequently, some of the water-soluble AAEM species become gaseous and are released from the coal char upon an increase in the pyrolysis temperature. Then, some minerals reach the surface of the char through cracks and holes at high temperatures. The char matrix exhibits an inhibition effect on the release of these species, resulting in the enrichment of the char surface with AAEMs. Therefore, Zhundong coal is suitable for preparing high value-added carbon materials by pyrolysis.

Impact of Water Pressure on the Organic Matter Evolution from Hydrous Pyrolysis

Deep oil and gas, as an important part to make up the energy-deficient. A series of breakthroughs had been made in their exploration and development in the past few years. However, the effects of deep fluids during hydrocarbon formation and evolution are still an ambiguous problem. Therefore, to investigate the effect of water pressure (PW) on hydrocarbon generation and thermal evolution of type-I, type-II, and type-III kerogens in a deeper stratum, three series of pyrolysis experiments were conducted on three samples with different kerogen types (types II₁, I, and III in TC, YMS, and XJ samples, respectively) in a high-temperature, high-pressure simulator. The type-I kerogen was pyrolyzed with 5, 20, 35, 50, 65, and 80 MPa water pressure at 375 °C for 48 h, whereas the type-II and type-III kerogens were pyrolyzed with 10, 20, 30, 40, 50, and 60 MPa water pressure at 350 °C for 48 h. The results showed that there was a threshold pressure PW affecting liquid hydrocarbons. In addition, before the threshold pressure, PW played a role in promoting, but then it was the inhibiting. For gaseous hydrocarbons, while the pressure effects and results were the same as with liquid hydrocarbons in TC samples under the near-critical or critical state, they had no obvious effects in YMS and XJ samples before the critical state, which proved that the organic matter (OM) evolution was associated with the state of fluid in the reaction system and the effects were stronger when the fluid was under the near-critical or critical state than when it is not under this state. The reasons could be concluded as follows: (1) the different properties of water, as the ionization product constant of water (K(w)) was higher in TC samples and may provide more H⁺ to participate in the OM reactions compared to YMS and XJ samples. Moreover, the particular characteristics of intersolubility with organic solvent occurred under near-critical or critical states, resulting in the more water-soluble hydrocarbons being expelled in TC samples. (2) Chemical mechanism: based on the first-order reaction equation for oil–gas generation and essential characters of samples and experiments, it can be concluded that the influence degree of PW on OM evolution was related to the type of OM, the thermal maturity as well as the nature of water. (3) Physical mechanism: the vapor in free space and generated hydrocarbons in pores were in a dynamic balance state, which also resulted in the existence of threshold pressure PW affecting OM evolution. Therefore, understanding the effects of PW on OM evolution would help us to study the oil–gas generation accurately in actual geology and help preferably in oil–gas exploration and exploitation.

The catalytic effect of manganese carbonate on kerogen pyrolysis in the absence and presence of water

To investigate the effect of Mn ore on the chemical components and isotopic compositions of gas products during kerogen pyrolysis in the absence or presence of water, a series of pyrolysis experiments on Type-I kerogen with manganese carbonate and/or water were conducted in closed gold capsules at 325–600 °C for 72 h with 300 bar. The heavy hydrocarbon gas yields increased significantly over 450 °C due to the participation of manganese. As for isotopic compositions, the manganese catalysis caused a decrease in the 13CCH4 and an increase in the 13CC2H6 over 475 °C; the δD values of methane generated during anhydrous pyrolysis with manganese carbonate are much lower than those produced by the pyrolysis of kerogen alone. Furthermore, the δD values are the most negative during hydrous pyrolysis with manganese ore. In addition to the thermal decomposition of manganese carbonate to form carbon dioxide, water provides sources of hydrogen and oxygen to form H2 and CO2. Manganese carbonate inhibits the association of sulfur-free radicals to hydrogen to form H2S. The i-C4/n-C4 ratio for gas products was evidently higher due to the existence of manganese and water, they can enhance the carbocation mechanism.

Experimental Investigation on Thermocatalytic Pyrolysis of HDPE Plastic Waste and the Effects of Its Liquid Yield over the Performance, Emission, and Combustion Characteristics of CI Engine

An experimental investigation was carried out to study two process parameters of thermocatalytic pyrolysis of high density polyethylene (HDPE) plastic waste, and the liquid yield of pyrolysis (plastic oil) was analyzed over its working characteristics in a direct injection compression ignition (DICI) engine. A series of pyrolysis experiments with four different heating rates (5, 10, 15, and 20 °C/min) were performed in identical environments with the objective of analyzing the heating rate and residence time on end products. It was found that the liquid yield was maximum at the heating rate of 10 °C/min and the residence time decreases with an increase in the heating rate due to variation of reaction kinetics at different heating rates. The characterization of the plastic oil revealed that the major constituents belong to alkene, alkane, and alcohol functional groups; totally 90 six fuel range hydrocarbons were present ranging from C5 to C28, and the other thermophysical properties were comparable with th...

Non-catalytic pyrolysis of scrap tires using a newly developed two-stage pyrolyzer for the production of a pyrolysis oil with a low sulfur content

The aim of this work was to reduce the sulfur content of pyrolysis oil derived from the scrap tire pyrolysis. In this respect, a series of pyrolysis experiments was conducted in both a fluidized bed reactor (one-stage pyrolysis) and a newly developed two-stage pyrolyzer consisting of an auger reactor and a fluidized bed reactor in series (two-stage pyrolysis). The one-stage pyrolysis was carried out at ∼500 and 600°C with different fluidizing gases (N2 and product gas). In the experiments, the pyrolysis oil obtained at ∼500°C had a lower sulfur content than that produced at ∼600°C. N2 was better at producing a low-sulfur pyrolysis oil than product gas. The sulfur contents of the oils obtained from the one-stage pyrolysis ranged from 0.75 to 0.92wt.%. The two-stage pyrolysis was conducted using product gas as the fluidizing medium at different auger reactor temperatures (∼230–450°C) and at a constant fluidized bed reactor temperature (∼510°C). A pyrolysis oil containing only 0.55wt.% of sulfur could be produced at the temperatures of the auger reactor of ∼330°C and fluidized bed reactor of ∼510°C. Moreover, the two-stage pyrolysis could produce an oil with a low nitrogen content (0.28wt.%). A pyrolysis oil obtained from the auger reactor contained dl-limonene up to 50wt.%.

Thermochemical and pore properties of goat-manure-derived biochars prepared from different pyrolysis temperatures

In this work, goat manure (GM) was evaluated as a potential feedstock for preparing biochar. Its thermochemical characteristics were first investigated by the proximate analysis, calorific value, organic and mineral component analysis, showing that the biomass obviously comprises a large percentage of volatile matter and less amount of fixed carbon. A series of pyrolysis experiments were conducted to produce biochars (i.e., GMBC) from dry GM at different pyrolysis temperatures (673, 773, 873, 973, and 1073K) held for 30min. To evaluate their potential for soil amendment and energy use, the resulting biochars were subject to the analyses of chemical and physical properties, including proximate analysis, elemental analysis, calorific value, mineral components, true density, and surface area/pore volume. Based on the thermochemical properties, pyrolysis temperature at around 873K seemed to be suitable for the production of GMBC, where its calorific value (CV) (i.e., 16.28MJ/kg) only increased about 25% as compared to CV of the dry GM (i.e., 13.06MJ/kg). However, the temperature of around 1073K was found to be the pyrolysis conditions for producing porous carbon-like material with the maximal BET surface area (over 93m2g−1) and porosity (about 0.115).

Effect of holding time during pyrolysis on thermochemical and physical properties of biochars derived from goat manure

The utilization of animal manure for biochar production has received much attention mainly due to the global warming and crop production. In this work, goat manure (GM) was evaluated as a potential feedstock for preparing biochars. Its thermochemical characterization was first investigated by the proximate analysis and thermogravimetric analysis (TGA), showing that the biomass obviously comprises a large percentage of lignocellulosic constituents. A series of pyrolysis experiments were conducted to produce biochars from dried GM at different holding times (0, 15, 30, 45, and 60 min) during the pyrolysis of 500 °C. To evaluate their potential for energy use and soil ameliorant, the resulting biochars were subject to the analyses of chemical and physical properties, including proximate analysis, calorific value, pore property (surface area and pore volume) and true density. The results showed that holding time is a less important process parameter influencing the characterization of goat-manure-derived biochars.

Kinetics of early methane generation from Green River shale

During oil/gas exploration in an area, there is a question as to whether methane in the strata was generatedin situ mainly by thermal degradation of local organic matter. The key to the question is whether the kerogen could produce methane of more than 80 mL/g TOC, when its Ro increased from initial (0.36%) to current value of 0.70% during thermal evolution. The authors have made efforts to answer this question by the kinetics method. First, a series of pyrolysis experiments were carried out to obtain data of methane yield and Ro evolution, from which kinetic parameters of methane and Ro were derived; then these parameters were extrapolated to the geological condition and finally, a methane yield, 96 mL/g TOC, was predicted. The result suggests that from the view of hydrocarbon generation, methane in the seam should be from thermal degradation of local kerogen.

The role of minerals in the thermal alteration of organic matter--IV. Generation of n-alkanes, acyclic isoprenoids, and alkenes in laboratory experiments.

A series of pyrolysis experiments, utilizing two different immature oil-prone kerogens ("type I": Green River Formation kerogen; "Type II": Monterey Formation kerogen) mixed with common sedimentary minerals (calcite, illite, or Na-montmorillonite), was conducted to study the effects of minerals on the generation of n-alkanes, acyclic isoprenoids, and alkenes during laboratory-simulated catagenesis of kerogen. The influence of clay minerals on the aliphatic hydrocarbons is critically dependent on the water concentration during laboratory thermal maturation. Under extremely low contents of water (i.e., dry pyrolysis, where only pyrolysate water is present), C12(+) -range n-alkanes and acyclic isoprenoids are mostly destroyed by montmorillonite but undergo only minor alteration with illite. Both clay minerals significantly reduce alkene formation during dry pyrolysis. Under hydrous conditions (mineral/water = 2:1), the effects of the clay minerals are substantially reduced. In addition, the dry pyrolysis experiments show that illite and montmorillonite preferentially retain large amounts of the polar constituents of bitumen, but not n-alkanes or acyclic isoprenoids. Therefore, bitumen fractionation according to polarity differences occurs in the presence of these clay minerals. By this process, n-alkanes and acyclic isoprenoids are concentrated in the bitumen fraction that is not strongly adsorbed on the clay matrices. The extent of these concentrations effects is greatly diminished during hydrous pyrolysis. In contrast, calcite has no significant influence on the thermal evolution of the hydrocarbons. In addition, calcite is incapable of retaining bitumen. Therefore, the fractionation of n-alkanes or acyclic isoprenoids relative to the polar constituents of bitumen is insignificant in the presence of calcite.

The role of minerals in the thermal alteration of organic matter—III. Generation of bitumen in laboratory experiments

A series of pyrolysis experiments, utilizing two different immature kerogens (from the Monterey and Green River Formations) mixed with common sedimentary minerals (calcite, illite, or Namontmorillonite), was conducted to study the impact of the mineral matrix on the bitumen that was generated. Calcite has no significant influence on the thermal evolution of bitumen and also shows virtually no adsorption capacity for any of the pyrolysate. In contrast, montmorillonite and illite, to a lesser extent, alter bitumen during dry pyrolysis. Montmorillonite and illite also display strong adsorption capacities for the polar constituents of bitumen. By this process, hydrocarbons are substantially concentrated within the pyrolysate that is not strongly adsorbed on the clay matrices. The effects of the clay minerals are significantly reduced during hydrous pyrolysis. The strong adsorption capacities of montmorillonite and illite, as well as their thermocatalytic properties, may in part explain why light oils and gases are generated from certain argillaceous source-rock assemblages, whereas heavy immature oils are often derived from carbonate source rocks.