Conventional Pyrolysis Method Research Articles

Continuous process design of the microwave chemical recycling of waste plastics using microwave-absorbing heating elements

Conventional pyrolysis methods to chemically recycle plastic waste require significant energy input owing to inefficient energy transfer from the heat sources to plastics and the generation of excess CO2. Accordingly, there is an urgent need to develop alternative methods for the chemical recycling of waste plastics to limit global warming. In this study, the use of microwaves (MWs) as an efficient energy source for pyrolysis and chemical recycling. However, because plastic is transparent to MW energy, a method that utilizes carbon materials as MW-absorbing heating elements (MWAHEs) was developed. This method directly converted high-density polyethylene (HDPE) into light chemicals in up to 94% yield with 45% ethylene selectivity. A two-stage pyrolysis system incorporating MWAHE-assisted MW pyrolysis was also developed to produce light chemicals in 95% yield with 49% ethylene selectivity. From a chemical engineering perspective, this two-step pyrolysis system is an efficient and feasible method for producing valuable light olefins. This study also demonstrates that MWAHE assisted MW pyrolysis is effective for the chemical recycling of plastic waste. This study offers potential solutions for the environmental problems posed by plastic waste by developing efficient and scalable methods for its chemical recycling.

PRODUCTION OF VALUE-ADDED BIOCHAR AND BIO-OIL FROM MICROWAVE CO2 PYROLYSIS OF MEDIUM-DENSITY FIBERBOARD WASTE

This study investigates the feasibility of using microwave CO2 pyrolysis to dispose of medium-density fibreboard (MDF) waste, a significant by-product of the furniture manufacturing industry. The primary goal is to transform MDF waste into valueadded biochar and bio-oil, exploring an alternative to conventional pyrolysis methods that typically use nitrogen (N2) as a purge gas. The research emphasises the potential benefits of CO2 utilisation in pyrolysis, both to enhance the quality of biochar and bio-oil and as a strategy for greenhouse gas (GHG) mitigation. This research reveals that conducting microwave pyrolysis in a CO2 atmosphere increases biochar (up to 44.8%) and bio-oil (up to 21.2%) yields over N2 pyrolysis. CO2 hinders volatile thermal cracking and aids in gas defragmentation and repolymerisation, with biochar yield rising with time and biooil peaking at an optimal duration. This study underscores microwave CO2 pyrolysis as a promising alternative for converting biomass waste into valuable products, potentially contributing to fuel utilisation. It also highlights the environmental benefits of this method, particularly in terms of CO2 utilisation, aligning with the broader objectives of sustainable waste management and renewable energy production. The findings provide a basis for future research in this area, focusing on optimising process parameters, exploring potential applications of bio-products, and assessing the economic and environmental viability of this innovative approach.

Efficient enrichment of uranium (VI) in aqueous solution using magnesium–aluminum layered double hydroxide composite phosphate-modified hydrothermal biochar: Mechanism and adsorption

This study presents the successful synthesis of Magnesium-aluminum layered double hydroxide composite phosphate-modified hydrothermal biochar for efficient removal of U(VI) from aqueous solutions. A novel synthesis approach involving phosphate thermal polymerization-hydrothermal method was employed, deviating from conventional pyrolysis methods, to produce hydrothermal biochar. The combination of solvent thermal polymerization technique with hydrothermal process facilitated efficient loading of layered double hydroxide (LDH) components onto the biochar surface, ensuring simplicity, low energy consumption and enhanced modifiability. Bamboo waste was utilized as the precursor for biochar, highlighting its superior green and sustainable characteristics. Additionally, this study elucidated the interactions between phosphate-modified hydrothermal biochar and LDH components with U(VI). Physicochemical analysis demonstrated that the composite biochar possessed a high surface area and abundant oxygen-containing functional groups. XPS and FTIR analyses confirmed the efficient adsorption of U(VI), attributed to chelation interactions between phosphate groups, magnesium hydroxyl groups, hydroxyl groups and U(VI), as well as the co-precipitation of U(VI) with multi-hydroxyl aluminum cations captured by LDH. The composite biochar reached adsorption equilibrium with U(VI) within 80 min and exhibited excellent fitting to the pseudo-second-order kinetic model and Langmuir model. Under conditions of pH = 4 and 298 K, it displayed significantly high maximum adsorption capacity of approximately 388.81 mg g⁻1, surpassing untreated biochar by 17-fold. The adsorption process was found to be endothermic and spontaneous and even after five consecutive adsorption-desorption cycles, the removal efficiency of U(VI) remained stable at 75.46%. These findings underscore the promising application prospects of Magnesium-aluminum layered double hydroxide composite phosphate-modified hydrothermal biochar in efficiently separating U(VI) from uranium-containing wastewater, emphasizing its environmental and economic value.

Fabrication of predesigned 3D carbon based microstructures via two-photon vat photopolymerization and susceptor-assisted microwave post-processing

This study presents a fabrication strategy for 3D carbon microstructures using via two-photon vat photopolymerization (2p-VPP) and susceptor-assisted microwave pyrolysis (SMWP). Fabricating carbon-based electrode materials with miniaturized functional structures is pivotal for developing high-performance electrochemical microdevices. However, efficiently producing these structures in the submicron regime with desired materials is still challenging. To address this, a hybrid microfabrication strategy was developed, and 3D carbon-based microstructures with submicron resolution were successfully produced. A carbon nanotube nanocomposite photoresist (SCNT-PR1) with improved dispersibility was first prepared. After a comprehensive printability assessment, 3D microstructures with a resolution of 833 ± 54 nm were produced using 2p-VPP. Through SMWP, the microstructures were transformed into pyrolytic carbon (PyC) nanocomposite microstructures with retained geometrical features. SMWP was shown to produce PyC with a less disordered carbon atomic structure, thanks to the accelerated pyrolysis reaction under MW irradiation, when compared to pyrolysis using a conventional furnace. The resistivity was reduced by over 75% from 0.69 ± 0.13 Ω cm to 0.16 ± 0.01 Ω cm, and enhanced electrochemical performance was confirmed. The fabricated PyC nanocomposite showed a further 12% reduction in electrical resistivity and a 20% lower charge transfer resistance for the redox reaction when using SCNT-PR1 as the precursor. Overall, this hybrid fabrication strategy demonstrates the advantages of producing 3D carbon microstructures with precise control over the geometric features and enhancing electrical and electrochemical properties compared to the conventional pyrolysis method. Its potential could be extended to the fabrication of miniaturized electrochemical devices, including microelectronics and point-of-care devices.

Edge-nitrogen synergize with micropores to realize fast and durable potassium storage for carbon anode

Edge-N (pyridinic/pyrrolic-N) functionalized carbon is a promising anode for potassium-ion batteries, while micropores have been proven to be effective in increasing capacity and cyclability. However, the obtained carbon materials usually exhibit a low N-doping level and edge-N species based on the conventional pyrolysis method, and the exploration of the synergistic effect of edge-N doping and micropores on the potassium-storage performance is still lacking. Herein, a novel strategy is proposed to prepare edge-N doped carbon (ENC-850) by directly pyrolyzing supermolecule precursors self-assembled by terephthalic acid (BDC) and melamine (MA). Because the s-triazine structure in MA is more stable than BDC, which can easily ensure a higher N-doping content in carbon, and the decomposition of s-triazine structure is accompanied by the release of NCNH2 gas, which enables most doped N-atoms to be of edge-N configurations, favoring the adsorption storage of K-ions. Besides, the released small molecules can create numerous micropores, not only providing active sites, but accommodating volume fluctuation. Therefore, the optimized ENC-850 with the most suitable edge-N content of 60.6% (7.73 at% of total 11.71 at% N-doping) and micropores delivers a high capacity (280 mAh g−1 at 0.5 A g−1) and superior cycling stability (over 2000 cycles).

Graphene-like Carbon Structure Synthesis from Biomass Pyrolysis: A Critical Review on Feedstock–Process–Properties Relationship

Biomass pyrolysis is a promising route for synthesizing graphene-like carbon (GLC) structures, potentially offering a cost-effective and renewable alternative to graphene. This review paper responds to the call for highlighting the state of the art in GLC materials design and synthesis from renewable biomass microwave pyrolysis. This paper includes an introduction of the microwave pyrolysis technology, information on feedstock variability and selection, discussion on the correlation between microwave pyrolysis process conditions and pyrolyzed product characteristics, and, more importantly, a section identifying any differences between pyrolyzing feedstock using the microwave pyrolysis method vs. conventional pyrolysis method. Furthermore, this work concludes by detailing the knowledge currently missing with the recommendation for future research/innovation directions.

Preparation of high performance porous carbon by microwave synergistic nitrogen/phosphorus doping for efficient removal of Cu2+ via capacitive deionization

Sargassum biochar has potential advantages as an electrode material due to its natural microscopic pore channels. However, conventional pyrolysis method is prone to thermal damage to the biochar, and incapable to form a complete pore structure resulting in poor biochar electrode performance. In this study, a strategy of microwave pyrolysis coupled with KOH activation was used to prepare nitrogen/phosphorus double-doped graded porous biochar (STC) using ammonium dihydrogen phosphate as dopant. The carbon material STC-1.24-800 prepared by the optimal parameters had a high specific surface area (SSA) of 1367.6 m2 g −1 and a total pore volume of 1.499 cm3 g−1. The precise inside-out heating characteristics of microwave facilitated the generation of suitable meso-micropore distribution ratios in carbon, and the graded porous structure provided abundant active sites for charge accumulation and ion diffusion. The doped nitrogen/phosphorus atoms responding to the microwave field, generated spin to promote microwave absorption, introducing surface structural defects to produce electron density differences. The change in the nature of the electron donor and its electron density enhanced the electrical conductivity and chemical stability of STC. Nitrogen/phosphorus polar surface functional groups improved hydrophilicity and wettability. STC-1.24-800 had a higher specific capacitance of 531 F g−1 and exhibits great cycle performance in capacitive deionization (CDI) applications (1.0 V, 50 mg L−1 Cu2+) as well as adsorption performance (56.16 mg g −1). The present work can provide a novel feasible idea for preparing diatomically doped graded porous biochar for CDI electrode application by microwave irradiation.

Preparation and characterization of Ce-MOF/g-C3N4 composites and evaluation of their photocatalytic performance

In this study, unique hybrid structures were constructed between a Ce-based metal-organic framework (Ce-MOF) and graphitic carbon nitride (g-C3N4) materials. In addition, the g-C3N4 materials used for these heterostructures were prepared by five different methods, namely the conventional pyrolysis method, chemical exfoliation by a strong acid, activation by an alkaline hydrothermal treatment, melamine-cyanuric acid supramolecular assembly with a mechanochemical method, and by the solvothermally pre-treated method. The structural and morphological properties of the resulting g-C3N4 sheets and their composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis-derivative thermogravimetry (TGA-DTG), diffuse reflectance UV–vis spectroscopy (UV–vis DRS) and N2 sorption-desorption isotherms (BET). Finally, the photocatalytic performance of the composites was determined by following the photocatalytic degradation of methylene blue (MB) in an aqueous solution under UV–visible light irradiation. It was found that the photocatalytic efficiency of the Ce-MOF/g-C3N4‒TS composite was significantly higher than that of their counterparts (Ce-MOF or g-C3N4‒TS) for the photocatalytic degradation of MB. When employing the composite, UV light-induced degradation of MB yielded an efficiency of 96.5% after 120 min for a dye solution containing 10 mg/L MB. This corresponds to a 5-fold or 2-fold improvement of the rate constant (k) when compared to the Ce-MOF or g-C3N4, respectively.

Selective transfer hydrogenation coupling of nitroaromatics to azoxy/azo compounds by electron-enriched single Ni-N4 sites on mesoporous N-doped carbon

Developing an active and selective non-precious metal catalyst to boost transfer hydrogenation coupling (THC) of nitroaromatics to their corresponding aromatic azoxy/azo compounds is desirable, but remains a great challenge. Herein, for the first time, we report a facile microwave-assisted pyrolysis strategy to successfully prepare the unique Ni-N4 sites on open-mouth quasi-stellate mesoporous N-doped carbon (NC) with enlarged electronic density led by the shortening Ni-N coordination distance (h-Ni1N4 /NC) by microwave heating the 1,10-phenanthroline-Ni complex coated stellate mesoporous SiO2 followed by alkali-leaching, distinct from the single-atom Ni-N5 sites on NC (l-Ni1N5/NC) prepared by a conventional pyrolysis method, unambiguously confirmed by diverse characterization technologies and DFT calculations. More importantly, h-Ni1N4/NC efficiently boosts the selective THC of nitrobenzene to azoxy under mild conditions using isopropyl alcohol (IPA) as hydrogen donor, showing much higher turnover frequency (33.4 h−1) and selectivity (95.6%) than traditional l-Ni1N5/NC catalyst (13.5 h -1°/85.3%) and supported Ni nanoparticles on NC (10.1 h -1, no detectable azoxy). Kinetic experiments and theoretical calculations reveal that the enriched electron density of Ni atoms in single Ni-N 4 sites efficiently lowers activation barrier for IPA/nitrobenzene activation and azoxy formation over h-Ni1N4/NC, which contributes to the outstanding catalytic performance for azoxybenzene production. Moreover, the approach was extended to the transformation of diverse nitroaromatics to corresponding azoxy compounds with high yield. In addition, by varying reaction parameters, h-Ni1N4/NC catalyst enables highly active and selective production of azo compounds via THC reaction of nitroaromatics.

Enhanced hydrogen production from anaerobically digested sludge using microwave assisted pyrolysis

Sewage sludge production has increased worldwide in recent years owing to continuous increase in the number of wastewater treatment plants. In Korea, disposal of sewage sludge in landfills is prohibited. Thus, an alternative, environmental-friendly sewage sludge treatment process is needed. Given its high organic matter content, sewage sludge is a potential energy source. In the present study, a pyrolysis method was utilized to produce energy from anaerobically digested sludge. In particular, to overcome limitations of conventional pyrolysis (CP) method, the microwave-assisted pyrolysis method (MWP), which is faster and more efficient, was applied. The efficiency of CP and MWP methods was compared at 400, 600, 800, and 1000 °C. The yield of 48% H2 in the gas generated using the MWP significantly surpassed that in the gas produced using CP. When the energy required for increases in temperature and H2 yield were compared, 800 °C was found to be the optimum temperature for both the methods. The microwave utilization improved the decomposition efficiency during the pyrolysis through rapid increases in temperature and direct internal heating. The application of heating element for maintaining the temperature of MWP was possible using bio-char generated in pyrolysis. The higher efficiency of the MWP relative to the CP was attributed to the associated lower energy required to raised and maintain the pyrolysis.

One-step synthesis of garlic peel derived biochar by concentrated sulfuric acid: Enhanced adsorption capacities for Enrofloxacin and interfacial interaction mechanisms

This study put forward a one-step carbonization method by concentrated sulfuric acid to prepare garlic peel derived biochar, and the synthetic conditions were optimized by L16(45) orthogonal experiments. Notably, in order to study the differences between the proposed synthetic method and the conventional pyrolysis method, the concentrated sulfuric acid carbonized garlic peels biochar (CSGPB) was compared with pyrolysis derived garlic peel biochar (HTGPB) in characterization and adsorption capacities for Enrofloxacin (ENR). Results showed that CSGPB exhibited more graphite-like structures with more active functional groups on the surface, and the equilibrium adsorption capacity of CSGPB (142.3 mg g−1) was 13.7 times of HTGPB (10.4 mg g−1) under identical conditions. Moreover, the adsorption behaviors including adsorption kinetics, isotherms and thermodynamics of CSGPB for ENR were fully investigated and discussed. Based on the above experiments, density functional theory (DFT) simulations were performed to reveal the interfacial interaction and adsorption mechanism. Results showed π-π interaction between quinolone moieties of ENR and graphite-like structures in CSGPB might be the dominant mechanism. As for the functional groups, the adsorption energies were −40.46, −15.21 and −5.96 kJ mol−1 for –SO3H, –OH and –COOH, respectively, which indicated –SO3H was the most active functional groups on the surface of CSGPB. This study provided a new sustainable perspective for the design of efficient biochars, and explored the interfacial interaction mechanism of antibiotics removal on biochars.

High-loading single-atom tungsten anchored on graphitic carbon nitride (melon) for efficient oxidation of emerging contaminants

Single-atom catalysts (SACs) have become an attractive concept in heterogeneous catalysis because of its high activity, selectivity and maximized utilization efficiency. However, constructing a high-loading SACs through conventional pyrolysis methods remains a challenge, because metal precursors usually have low thermal stability and the decrease of particle size will lead to an increase of surface energy. Herein, we used dicyandiamide to tailor the metatungstate and fix the W atoms during the thermal polymerization process, finally obtained a new kind of W-SAC (single W atoms anchored on graphitic carbon nitride, named as W-CN) with a high-loading of 11.16 wt% and a unique O, N coordination. The electrospray ionization high-definition mass spectrometry (ESI-HDMS) revealed that single W atoms were introduced into graphitic carbon nitride via the polycondense of W-containing dicyandiamide intermediate. The unique atomically dispersed N-W-O3 moieties, which promoted the separation efficiency of photogenerated electron-hole pairs, were identified by Aberration-corrected scanning transmission electron microscopy (AC-TEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure spectroscopy (XAFS) and Density functional theory (DFT) calculation. Moreover, compared to pure CN, the W-CN exhibited an enhanced catalytic performance for the oxidation of carbamazepine (CBZ) under solar light irradiation. The experiment results revealed that photogenerated holes (h+), superoxide radicals (•O2−), and singlet oxygen (1O2) were the predominant active species and played an important role in eliminating emerging contaminants. This work paves a facile and efficient path toward high-loading SAC, and opens new insight into tracking SAC structure evolution.

Quantitative Measurement of Retained Oil in Organic-Rich Shale—A Case Study on the Chang 7 Member in the Ordos Basin, China

This study proposes a method to calculate the retained oil content (WO) in cores collected by a sealed tool from organic-rich shale with thermal maturity around%Ro = 0.8 in the Ordos Basin, China. Approaches such as soaking cores at low temperature, multiple extractions, multiple pyrolysis, and multiple chromatographic analyses were conducted and then the relationships between total retained oil content and mineral compositions were analyzed. The total retained oil content measured by the method proposed in this paper is 60–260% higher than that measured by a conventional pyrolysis method and 34–69% higher than the sum (WO) of two extractions with dichloromethane (WO3) and chloroform (WO4). After extractions with dichloromethane and chloroform (WO5), the oil retained in the organic-rich shale was 4.7–11.6%, which has not been extracted. Positive correlations exist between WO (i.e., WO3 + WO4) and total organic carbon (TOC) and S1 (absorbed hydrocarbon by rock pyrolysis), and WO has the highest correlation coefficient with the former. The method can provide important guidance for the objective analysis of retained oil in organic-rich shale, and it is reliable for the evaluation of shale oil reserves.

Plasma deposition of parylene-C film

A new method that uses plasma energy for the deposition of parylene-C films is presented. The equipment and instrumentation for the plasma deposition of parylene-C films were developed and constructed by combining evaporation and plasma-generating units. The plasma deposition of parylene-C films consists of three steps: evaporation, decomposition of the parylene-C dimers using plasma, and deposition of the film. The entire deposition process from evaporation to deposition was designed to be completed within 20 min for a parylene-C film with a thickness of less than 200 nm. The thickness of the parylene-C film was controlled in the range of 100–200 nm by adjusting the amount of parylene-C dimer as well as the plasma energy. The parylene-C films prepared by plasma deposition were characterized and compared with those obtained using the conventional pyrolysis method. The comparison included the chemical properties (chemical functional groups, atomic compositions) and their physical properties (density, crystallinity, absorption in the visible wavelength range, surface roughness and contact angle).

Cleaner conversion of bamboo into carbon fibre with favourable physicochemical and capacitive properties via microwave pyrolysis combining with solvent extraction and chemical impregnation

Bamboo was converted into carbon fibre using a novel approach combining microwave pyrolysis, solvent extraction, and chemical impregnation. The employment of solvent extraction and chemical impregnation transformed natural bamboo into bamboo fibre with yield of 64 wt% that comprised of 87 wt% cellulose, 4 wt% lignin and 9 wt% hemicellulose deemed desirable for conversion into carbon fibre. The subsequent use of microwave pyrolysis transformed the bamboo fibre to form carbon fibre; the effects of microwave irradiation time and microwave power (two key process parameters) on properties of carbon fibre were investigated. Microwave pyrolysis provides a rapid heating rate (30 °C/min) with relatively shorter process time (20 min) compared to that performed by conventional pyrolysis method, thus leading to a relatively lower electric consumption and providing a potentially cost-saving and energy-efficient approach to produce carbon fibre. The production and properties of carbon fibre produced were affected by irradiation time and microwave power. The carbon fibre obtained was detected to have high fixed carbon (80 wt%), carbon element (87%), high BET surface area (475 m2/g) and fibres in small diameter (≤1 μm). It also shows desirable features comprising low content of moisture (<6 wt%), inorganic elements of Na, K, S, Mg (≤5%) and ash (1 wt%), allowing the carbon fibre to have more active sites and making it a cleaner product rather than polluting the environment whereas a high ash content could lead to undesired catalytic reactions and emission of potentially hazardous metallic components present in the ash. Combined with the detection of positive capacitive behaviour, the carbon fibre shows great potential to be used as an electrode for energy storage application. The results disclose that microwave pyrolysis combining with solvent extraction and chemical impregnation can be a cleaner approach to transform bamboo into carbon fibre with favourable physicochemical and capacitive properties.

Molten alkali carbonates pyrolysis of digestate for phenolic productions

Molten alkali carbonates (MC) pyrolysis technology is proposed to dispose digestate waste and convert it into high value-added phenolics in this work. The results showed that temperature strongly affected phenolic production by promoting the depolymerization of lignin, while particle size had less influence on phenolic productions owing to the catalysis and dynamic diffusion of alkali metal ions. Meanwhile, the effect of mass ratio between sample and molten carbonates was investigated by a series of differentiated proportions from 5 to 25%. The optimum reaction conditions were 10% of mass ratio in a particle size from 0.6 to 0.85 mm at 450 °C, with the maximum phenolics yield of 67.08% in organic. In sum, 5.6 g of phenolics and 0.96 g of guaiacols were generated from 100 g of digestate. Compared with conventional pyrolysis method, the methoxyl group in liquid product could be efficiently removed at atmosphere in molten carbonates. Additionally, thermogravimetric analysis further demonstrated that alkali metal ions (Li+, Na+ and K+) promoted the primary degradation of lignin and secondary monomolecular dissociation reactions of methoxyphenol.

Production of bio-oil and bio-char from different biomass wastes

Environmental pollution is rising due to the excess use of fossil fuels causing severe global warming and acid rains. High market price and the limited amount of fossil fuels have caused energy crises worldwide especially in the underdeveloped countries. The huge amount of biomass organic wastes is being widely used as an alternative feedstock as a potential source for second generation biorefining process. In this research four different biomass wastes are used to investigate the yield of bio-oil and biochar using a conventional pyrolysis method. Rice husk, bagasse, sawdust (Dalbergia sisso Roxb.), and sawdust (Populus caspica Bornm.) are operated in a fixed bed reactor. The rationale of this study is to evaluate the effect of temperature on the yield of bio-oil and biochar at three different temperatures (300 °C, 400 °C, and 500 °C) with heating rate of 3.69 °C/min. The particle size of each biomass waste used was 0.498 mm. Sulfuric acid was used as a catalyst to enhance the rate of reaction. The proximate analysis of biomass wastes was performed in order to evaluate the moisture content, ash content, and volatile matter and fixed carbon. The results showed that with the increase of temperature, the bio-oil yield increases and biochar yield decreases. The highest yield of bio-oil (32.39%) was achieved at 500 °C from bagasse feedstock and the highest yield of biochar (37.50%) was obtained at 300 °C from rice husk feedstock.

High Yield of Hydrocarbons from Catalytic Hydrodenitrogenation of Indole under Hydrothermal Conditions

We report herein on a new method to achieve a high yield of hydrocarbons from hydrothermal catalytic hydrodenitrogenation (HDN) of indole, which is higher than that from conventional pyrolysis methods. The main hydrocarbon products were aromatic hydrocarbons and alkanes, which are similar to fossil oils to be used as liquid fuels in the future. Catalyst screening experiments show that noble metal catalysts (e.g., 5 wt % Pt, Pd, or Ru) supported on porous solids (e.g., carbon, Al2O3) enhanced the conversion of indole to hydrocarbons under hydrothermal condition. Of those different catalysts, Pd/γ-Al2O3 shows the greatest influence on the yield of hydrocarbons, which we focus on the catalyst Pd/γ-Al2O3 in more details. On the basis of the Pd/γ-Al2O3 catalyst, the effects of time, temperature, and H2 pressure on the hydrocarbons were discussed. HDN of the indole reaction at 450 °C, 0.015 g/cm3 water density, 5 MPa H2, and 50 wt % Pd/γ-Al2O3 loading led to a maximum yield (51 mol %) of hydrocarbons at 120 min...

Simulation of hydrocarbons pyrolysis in a fast-mixing reactor

Currently, thermal decomposition of hydrocarbons for the production of basic petrochemicals (ethylene, propylene) is carried out in steam-cracking processes. Aside from the conventional method, under consideration are alternative ways purposed for process intensification. In the context of these activities, the method of high-temperature pyrolysis of hydrocarbons in a heat-carrier flow is studied, which differs from previous ones and is based on the ability of an ultra-short time of feedstock/heat-carrier mixing. This enables to study the pyrolysis process at high temperature (up to 1500K) at the reactor inlet. A set of model experiments is conducted on the lab scale facility. Liquefied petroleum gas (LPG) and naphtha are used as a feedstock. The detailed data are obtained on temperature and product distributions within a wide range of the residence time. A theoretical model based on the detailed kinetics of the process is developed, too. The effect of governing parameters on the pyrolysis process is analyzed by the results of the simulation and experiments. In particular, the optimal temperature is detected which corresponds to the maximum ethylene yield. Product yields in our experiments are compared with the similar ones in the conventional pyrolysis method. In both cases (LPG and naphtha), ethylene selectivity in the fast-mixing reactor is substantially higher than in current technology.

Comparing Characteristics of Oil Palm Biochar Using Conventional and Microwave Heating

Microwave heating technique is one of the most attractive alternative applications in the thermal conversion process. In addition, microwave pyrolysis is one of the thermochemical technologies using microwave irradiation heating in order to obtain biofuels and materials from biomass. Microwave pyrolysis not only overcomes the disadvantages of conventional pyrolysis methods such as slow heating, but also improves the quality of final pyrolysis products. Recently, the biomass from oil palm wastes (empty fruit bunch, oil palm shell and oil palm fiber) has been gaining more attention in order to produce the biochar. In addition, biochar is important for sequestering carbon and as an effectively additive to improve soil fertility, aid sustainable production, reduce contamination of water streams. This paper focused on the comparison of biochar characteristics produced from oil palm biomass via microwave heating and conventional heating. Analysis on the characteristics of the biochar includes its physical properties, proximate and elemental analysis, the Brunauer- Emmet- Teller (BET) surface area and Scanning Electron Microscopy (SEM).