Simultaneous Pyrolysis Research Articles

CoP/N‐Doped Carbon Nanowire Derived from Co‐Based Coordination Polymer as Efficient Electrocatalyst toward Oxygen Evolution Reaction

The development of cheap, high‐efficiency, and long‐term durable oxygen evolution reaction (OER) electrocatalysts has become a research hotspot. Carbon‐confined transition‐metal phosphides derived from coordination polymers and metal–organic frameworks have received great attention. Herein, a CoP/N‐doped carbon‐400 (CoP/NC‐400) nanowire is prepared using a coordination polymer [Co(C4H7NO4)]·xH2O (Co‐Asp, Asp = l‐aspartic acid) nanowire as the precursor and template through simultaneous pyrolysis and low‐temperature phosphidation. Electrochemical tests indicate that the CoP/NC‐400 nanowire displays better OER properties than CoP/NC‐300/500 nanowires. The overpotential required to reach a current density of 10 mA cm−2 is 320 mV with a minimum Tafel slope of 89 mV dec−1. Moreover, at a higher current density, the OER performance of the CoP/NC‐400 nanowire is superior to that of RuO2. The excellent electrochemical performance of the CoP/NC‐400 nanowire is attributed to the high electrochemical surface area and the strong synergistic effect of the CoP nanoparticle and the N‐doped carbon nanowire.

Dry reforming of methane catalysed by molten metal alloys

Dry reforming of methane usually affords low-quality syngas with equimolar amounts of CO and H. Here we report the high conversion of CH and CO to syngas and solid carbon through simultaneous pyrolysis and dry reforming of methane in a bubble column reactor using a molten metal alloy catalyst (65:35 mol% Ni:In). The H to CO ratio can be increased above 1:1 using feed ratios of CH:CO greater than 1:1 to produce stoichiometric solid carbon as a co-product that is separable from the molten metal. A coupled reduction–oxidation cycle is carried out in which CO is reduced by a liquid metal species (for example, In) and methane is partially oxidized to syngas by the metal oxide intermediate (for example, InO), regenerating the native metal. Moreover, the H:CO product ratio can be easily controlled by adjusting the CH:CO feed ratio, temperature, and residence time in the reactor.

Pyrolysis coupled anaerobic digestion process for food waste and recalcitrant residues: Fundamentals, challenges, and considerations

AbstractFood waste (FW) is a severe environmental problem all over the world, and the recalcitrant organic residues (ROR) from FW treatment plant operations are also a critical environmental issue due to unsustainable treatment and disposal techniques. Requirements for FW and ROR complete exploitation with the establishment of recycling‐renewable technologies are very crucial. This paper review AD and pyrolysis as two promising technologies to degrade FW and its residues, creating numerous renewable bioenergy yields with value‐added. Existing oil/tar application methods in the AD suffered from various problems such as microorganism toxicity and limited productivity. Future upgrading techniques considering the second‐stage pyrolysis process to decompose oil/tars for syngas with high hydrogen content and enhanced bio‐methanation in the AD were addressed. Simultaneous pyrolysis by‐product recycle in the AD during the valorization of FW are aimed to have the features of sustainability toward increased bioenergy production, reactor efficiency, and agricultural application.

Ionisable emerging pharmaceutical adsorption onto microwave functionalised biochar derived from novel lignocellulosic waste biomass

Functionalised biochar (WpOH) was prepared from wild plum kernels using simultaneous pyrolysis and microwave potassium hydroxide (KOH) functionalisation. This was then applied to the removal (from water) of an ionisable pharmaceutical - naproxen (NPX). Characterization of the WpOH was carried out using pHpzc, SEM/EDX, BET, FTIR, XRD, and the principle adsorption mechanisms were thoroughly studied. A pseudo-second order kinetic model best described the reaction kinetic behaviour, and the Langmuir isotherm provided the best fit to the results. The maximum adsorptive interaction (73.14 mg/g) occurred between pH 5 and 7 through electrostatic attraction (the main interaction mechanism) between the negatively charged NPX and the positively charged WpOH functional groups. In addition, hydrogen-bonding and electron-donor-acceptor (EDA) interactions were important. In a competitive study, using NPX and carbamazepine (a basic/amphoteric drug), the different nature/structure of the two compounds resulted in slight competitive adsorption. The results demonstrate the potential for wild plum kernel biochar to be used in the efficient removal of emerging contaminants such as pharmaceuticals from water.

Facile and low-cost fabrication of ZnO/biochar nanocomposites from jute fibers for efficient and stable photodegradation of methylene blue dye

The present work demonstrates the fabrication of ZnO loaded on biomass porous carbon through pyrolysis of jute fibers pretreated by Zn(OAc)2. XRD, Raman SEM, TEM, XPS and physical adsorption of nitrogen were used to characterize the products. Dark adsorption and photocatalytic degradation of methylene blue (MB) was run to evaluate their activities for removal of organic pollutants. It was demonstrated that the composition and structure of ZnO/JFC composites depended on the ratios of jute fibers to zinc salt. Through adjusting the mass ratio between raw materials, a fine composite of ZnO monocrystalline nanorods embedded on the porous carbon walls was obtained, which exhibited a much better efficiency for MB decolorization. The removal of MB was found to be pH dependent, and the optimized removal efficiency reached to 99% and the mineralization level was over 93% at pH 7.0 following 30 min under UV illumination. The kinetic studies showed the decolorization of MB followed pseudo first-order kinetics, and the rate constants were determined using the Langmuir–Hinshelwood model, indicating KLH = 0.024 L∙mg−1and kc = 4.01 mg∙L−1 min−1. Moreover, the ZnO nanorods/JFC composite was stable and showed a high efficiency of over 80% during seven cycles of utilization and regeneration. Examination for the real sample contaminated by MB proved that the presence of metal ions and other organic pollutants hardly affected its photocatalytic ability. It was demonstrated that ZnO/JFC composites could be fabricated through simultaneous pyrolysis of jute fibers and zinc acetate. These composites were provided with the advantages of high photocatalytic efficiency, convenient recycling and long-term stability, and were expected to be applied in environmental engineering and manufacturing for organic dyes removal.

Thermal studies on the starch-g-copolymers prepared from two terpene acrylate monomers under oxidative conditions

The simultaneous thermal studies (TG/DTG/DSC) coupled with the FTIR analysis of the gaseous decomposition products created under oxidative heating of starch-g-poly(neryl acrylate) and starch-g-poly(geranyl acrylate) copolymers have been presented. To these studies, the copolymers with the following grafting percents (G) were selected: starch-g-poly(neryl acrylate) copolymers: 36.6 ± 0.3%, 40.3 ± 0.4%, 42.8 ± 0.4% and starch-g-poly(geranyl acrylate) copolymers: 28.9 ± 0.2%, 32.4 ± 0.6%, 35.6 ± 0.4%. The performed tests proved that the thermal resistance of the copolymers was strongly dependent on their G values, despite a small difference in the G values between the samples. The slight increase (ca. 6.2–6.7%) in the G value caused the significant drop of the thermal stability of all the studied materials. The TG/DTG/DSC studies confirmed at least three-stage decomposition mechanism of the copolymers where simultaneous pyrolysis, oxidation, dehydration and decarboxylation processes took place. The TG/FTIR analyses showed the emission of various structure fragments; among them, one can mention the creation of some organic fragments such as aldehyde, acid, alkene, alkane, furan fragments, CH4 and inorganic species (CO2, CO, H2O) as a result of the oxidative decomposition processes of the studied copolymers. In addition, the conducted studies demonstrated similar decomposition course and mechanism for both types of the copolymers, regardless of the monomer type used to the graft process.

Assembling biochar with various layered double hydroxides for enhancement of phosphorus recovery.

Highly efficient and cost-effective adsorbents for phosphate (P) recovery are the key to control eutrophication and recover phosphorus from waste streams to enhance food production. This study assembled corn stalk-derived biochar (BC) with various forms of layered double hydroxides (LDHs) (B-M-LDH) through simultaneous pyrolysis of waste biomass and metal (i.e., Zn/Al, Mg/Al, and Ni/Fe) hydroxide precipitates. Batch sorption experiments evaluated the kinetics and isotherms of phosphate adsorption as well as the influence of pH value and co-existing anions. Morphological characterization showed that crystalline LDH flakes were impregnated within the framework of fabricated B-M-LDH composites. Superior P adsorption capacity (152.1 mg (P) g-1) and fast Elovich kinetics (5925 mg g-1 h-1) could be achieved by the B-Zn/Al-LDH composite at pH 5. The P adsorption onto BC-LDHs was pH dependent and subjected to adverse influence of co-existing anions. Interlayer anion exchange and surface complexation were probably the predominant adsorption mechanisms at the studied phosphate concentration. Therefore, BC can be functionalized as mineral composites for enhancing P recovery and wastewater treatment.

Pyrolyzing Renewable Sugar and Taurine on the Surface of Multi-Walled Carbon Nanotubes as Heterogeneous Catalysts for Hydroxymethylfurfural Production

Conversion of biorenewable feedstocks into transportation fuels or chemicals likely necessitates the development of novel heterogeneous catalysts with good hydrothermal stability, due to the nature of highly oxygenated biomass compounds and the prevalence of water as a processing solvent. The use of carbon-based materials, derived from sugars as catalyst precursors, can achieve hydrothermal stability while simultaneously realizing the goal of sustainability. In this work, the simultaneous pyrolysis of glucose and taurine in the presence of multi-walled carbon nanotubes (MWCNTs), to obtain versatile solid acids, has been demonstrated. Structural and textural properties of the catalysts have been characterized by TEM, TGA, and XPS. Additionally, solid state nuclear magnetic resonance (ssNMR) spectroscopy has been exploited to elucidate the chemical nature of carbon species deposited on the surface of MWCNTs. Al(OTf)3, a model Lewis acidic metal salt, has been successfully supported on sulfonic groups tethered to MWCNTs. This catalyst has been tested for C6 sugar dehydration for the production of HMF in a tetrahydrofuran (THF)/water solvent system with good recyclability.

Simultaneous pyrolysis and trimethylsilylation with N-methyl-(trimethylsilyl) trifluoroacetamide for the characterisation of lignocellulosic materials from kraft pulping

AbstractSimultaneous pyrolysis and trimethylsilylation (SPyT) withN-methyl-(trimethylsilyl)trifluoroacetamide (MSTFA) was used to characterise lignocellulosic materials from pine and eucalyptus obtained by kraft pulping. This approach protects the carboxyl groups and helps preserve the original structure of phenolic products during analytical pyrolysis, and so that pyrolysis and derivatisation occur simultaneously and the fragments of underivatised compounds are also silylatated. The SPyT products are representative for the structures present in carbohydrates and lignin of the investigated materials. The method is also suited to semi-quantitative evaluation also in terms of detection of condensed lignin structures in pulps and kraft lignins.

Spray-pyrolyzed Al2O3-Ag Nano-Cermets coatings for solar absorbers

In this work, it is shown the feasibility for obtaining silver nanoparticles by ultrasonic spray pyrolysis and their simultaneous incorporation during deposition of thin layers of aluminum oxide to get a Cermet coating of Al2O3-Ag. The synthesis of these Cermets was achieved on the basis of both the simultaneous pyrolysis of silver nitrate and aluminum acetylacetonate on different substrates: Quartz, glass, crystalline silicon (c-Si), and titanium at temperatures of 500, 550 and 600 °C. The optical and structural properties of the Cermets were studied by Scanning Electron Microscopy, Atomic Force Microscopy, X-ray diffraction, UV-vis, UV-vis-IR and FT-IR spectroscopies. UV-Vis spectroscopy showed that the intensity of the absorption peak (plasmon) was limited to the concentration of silver nitrate, and it shifted toward shorter wavelengths with the decrease in the size of the Ag nanoparticles inside the Cermets. The plasmon position of Ag nanoparticles in the different samples was found to be centered at 504 nm, 506 nm, 497 nm and 475 nm for samples deposited with 0.1 mol, 0.05 mol, 0.02 mol, and 0.01 mol of Ag(NO3), respectively. The shape of the Ag nanoparticles was approximately spherical, ranging from 4 nm to 35 nm, and their concentration was proportional to the concentration of Ag(NO3) included in the spray solution. By means of the UV-Vis Spectroscopy-IR and FT-IR, in the best of cases, a solar absorptance of 0.83 and an infrared thermal emittance of 0.14, for a sample of Al2O3-Ag prepared with 0.1 mol of Ag(NO3) in the precursor solution, were obtained.

Selective reductive cleavage of C[sbnd]O bond in lignin model compounds over nitrogen-doped carbon-supported iron catalysts

Lignin has recently attracted much attention as a promising resource to produce fuels and aromatic chemicals. The selective cleavage of CO bond while preserving the aromatic nature has become one of the major challenges in the catalytic valorization of lignin to aromatic chemicals. In this work, we report that the selective reductive cleavage of CO bond in lignin model compounds can be successfully achieved through heterogeneous iron catalysis. The hydrogenolysis of α-O-4 model linkage shows that the iron catalyst prepared by the simultaneous pyrolysis of iron acetate and 1,10-phenanthroline on activated carbon at 800 °C is the most active iron catalyst, affording phenol and toluene with yields of 95% and 90%, respectively. This aromatics selectivity is found to be much higher than that obtained over noble metal catalysts. The presence of N⋯Fe species as the active center of heterogeneous iron catalyst was confirmed by various technologies especially XPS and H2-TPR. For the β-O-4 model linkage, the vicinal OH group was essential for the iron-catalyzed hydrogenolysis of ether linkage. The oxidation of the α-carbon in the β-O-4 model compounds can significantly decrease the bond dissociation energy of ether linkage, giving depolymerization products in moderate to excellent yields.

A high performance nitrogen-doped porous activated carbon for supercapacitor derived from pueraria

In this work, pueraria-based biomass nitrogen-doped porous activated carbon (NPC) was prepared by a simple two-step approach. Firstly, pueraria powder and melamine were fully mixed and hydrothermally treated. Secondly, the as-formed product was directly subjected to the oven for the simultaneous pyrolysis and activation. The as-prepared samples were systematically characterized by SEM, TEM, XPS, XRD, and N2 sorption isotherms techniques. The as-prepared NPC exhibited a high BET surface area of 2321 m2 g−1 with 99% small-size mesoporous structures. In 6 M KOH electrolyte, the NPC electrode delivered a high specific capacitance of 250 F g−1 at a current density of 0.5 A g−1. Even at 10 A g−1, specific capacitance of 231 F g−1 was obtained. Furthermore, an energy density of 8.46 Wh kg−1 at a power density of 123 W kg−1 was obtained with the NPC electrode in a supercapacitor, and it still retained a specific energy density of 7.52 Wh kg−1 at a power density of 2417 W kg−1.

Urchin-Shaped Bi2S3/Cu2S/Cu3BiS3 Composites with Enhanced Photothermal and CT Imaging Performance

Urchin-shaped Bi2S3/Cu2S/Cu3BiS3 nanocomposites were successfully prepared in this study through one-pot synthesis, which involved microwave-assisted simultaneous pyrolysis of two precursors. The as-prepared Bi2S3/Cu2S/Cu3BiS3 hybrids exhibit stronger absorption in the near-infrared regime than the individual components, i.e., Bi2S3, Cu2S, and Cu3BiS3. The photothermal conversion efficiency (η) of Bi2S3/Cu2S/Cu3BiS3 composites can even reach 43.8%, which is significantly higher than that seen with most of the transition metal chalcogenide materials. The excellent photothermal performance of Bi2S3/Cu2S/Cu3BiS3 hybrids is likely arising from its unique urchin-like structure, in which needle-like Bi2S3/Cu2S nanocomposites grow from the core of Cu3BiS3. The copresence of Bi2S3 and Cu2S also leads this newly synthesized composite to produce high contrast for X-ray computer tomography imaging, an important property required for a great potential application in theranostic cancer treatment.

High-temperature solvent-free sulfidation of MoO3 confined in a polypyrrole shell: MoS2 nanosheets encapsulated in a nitrogen, sulfur dual-doped carbon nanoprism for efficient lithium storage.

Hierarchical nanostructured metal sulfides in a rectangular prism shape are highly attractive as a promising electrode material for lithium ion energy storage. Herein, we develop a simultaneous pyrolysis and sulfidation strategy to synthesize yolk-shelled MoS2@nitrogen, sulfur dual-doped carbon (MoS2@NSC) nanoprisms. Upon encapsulating MoO3 nanoprisms into a polypyrrole (PPy) shell, a high-temperature solvent-free sulfidation reaction from MoO3 to hierarchical MoS2 nanosheets could take place within the PPy nanoreactor, and the PPy nanoreactor simultaneously converted into NSC hollow nanoprisms. Owing to the compositional and structural superiority, the MoS2@NSC nanoprisms with a well-defined sheet-in-prism superstructure manifested enhanced electrochemical activity as a promising anode material for lithium-ion batteries including a high reversible capacity (960 mA h g-1 at 0.1 A g-1), excellent cycling stability (800 mA h g-1 at 0.1 A g-1 up to 300 cycles), and superior rate capability (440 mA h g-1 at 2 A g-1).

Two-stage catalytic fast hydropyrolysis of biomass for the production of drop-in biofuel

The major obstacles for the production of drop-in fuel from traditional fast pyrolysis are low bio-oil yield, poor fuel heating value and high solid yield. To overcome these obstacles, we studied the introduction of high pressure hydrogen into the pyrolysis reactor, in a process known as catalytic fast hydropyrolysis (CFHP). CFHP of anisole, a bio-oil model compound, was performed at different temperatures and pressures, to determine the effects of those variables on the CFHP reaction network. Alkanes were observed at low temperature and high pressure, whereas aromatics were dominant at low pressure and high temperature. Aspen modelling and calculation of reaction equilibrium constants showed that there is a thermodynamic barrier for simultaneous pyrolysis and hydrogenation at 600 °C. Reduced heating rates and CFHP followed by second-stage hydroprocessing (SH) were proposed as a means to control reaction temperature and efficiently deoxygenate CFHP vapors. The two-stage CFHP followed by hydroprocessing produced nearly 18 mol% carbon yield to alkanes, and a total bio-oil carbon yield of 25 mol%. The approximate bio-oil higher heating value (HHV) and aromaticity were 43.4 MJ/kg and 28 wt%, respectively, both within the range of gasoline.

Graphitic Carbon Nitride (g‐C3N4)‐derived Fe‐N‐C Catalysts for Selective Hydrodeoxygenation of 5‐Hydroxymethylfurfural to 2,5‐Dimethylfuran

AbstractAs Fe is more abundant and economic than Cu and Ni, it is probably a more attractive non‐noble alternative to precious metals in biomass conversions, for which usually require promising catalysts for large‐scale production. In this work, economic and environmental benign heterogeneous iron catalysts prepared by simultaneous pyrolysis of graphitic carbon nitride and iron precursors on activated carbon, were demonstrated to be active for the hydrodeoxygenation of biomass‐derived 5‐hydroxymethylfurfural to 2,5‐dimethylfuran. The effect of pyrolysis temperature, support, iron content, the type of g‐C3N4 and iron precursor, and N/Fe ratio were explored thoroughly, and reaction parameters such reaction temperature and H2 pressure were also investigated. The highest DMF yield of 85.7 % was obtained at 240 °C for 3 h, which is comparable to that obtained over iron catalysts prepared from precious iron complexes. The investigation of reaction pathway showed that 5‐methylfurfural was the possible intermediate. The stability of as‐prepared Fe‐N‐C catalyst could be improved after treatment with aqueous HCl solution.

Simultaneous pyrolysis of microalgae C. vulgaris, wood and polymer: The effect of third component addition

Due to the depletion of fossil fuels and their environmental issues, it is necessary to find energy resources which are renewable. Biomass becomes promising feedstock for bio-fuel production. The aim of this study is to investigate thermal decomposition behavior and the effect of third component on the binary mixture pyrolysis using thermogravimetric analysis (TGA). Experiments were carried out at heating rates of 10, 20 and 40°C/min from ambient temperature to 600°C. Two divided groups of peaks were observed in DTG curve of tertiary mixture which the first one was corresponded to microalgae and wood and the second one was belonged to polymer. It is stated that microalgae and wood can improve the degradation process while polymer can delay the decomposition process of mixture. Mentioned positive effect of microalgae and wood could be related to main decomposition temperature and component of microalgae and wood. On the other hand, polymer reduces weight loss of binary mixture and has negative effect of it. The kinetics analysis showed that activation energy (E) and pre-exponential factor (A) of tertiary mixture was slightly lower than that of microalgae-polymer mixture which had the lowest E and A.

Metal–carbon C/Co nanocomposites based on activated pyrolyzed polyacrylonitrile and cobalt particles

A new way of synthesizing metal–carbon nanocomposites via simultaneous pyrolysis and the chemical activation of a precursor based on polyacrylonitrile and cobalt carbonate under IR radiation is proposed. Structural characteristics of samples synthesized both without alkali and in the activation process are compared. The effect the metal has on the structure of the carbon and the size of its specific surface area is shown. The specific surface area of the sample synthesized with the simultaneous formation of the carbon matrix, its activation, and the reduction of the metal is 1232 m2/g. Cobalt nanoparticles are found to have cubic face-centered and hexagonal close-packed lattices.

Grinding pyrolysis of Mallee wood: Effects of pyrolysis conditions on the yields of bio-oil and biochar

A novel technology termed as ‘grinding pyrolysis’ has been developed in response to the limitations hindering the commercialisation of existing fast pyrolysis technologies. Some of the features of this novel technology include capability of feeding biomass having a wide range of particle sizes in the same feedstock, simultaneous pyrolysis and grinding, no requirement for a fluidising gas and simplified requirement for cooling and condensing the pyrolysis products. A pilot plant was developed to study the effects of various operating conditions on the yields of bio-oil and biochar. Experiments have been done using mallee biomass grown in Western Australia. Feed particle sizes of up to a few centimetres have been used successfully. It was proved that the simultaneous grinding and pyrolysis helps liberating volatiles from a pyrolysing biomass particle and is capable of producing higher organic yields than pyrolysis without grinding. The effective size of a pyrolysing particle was significantly decreased by the simultaneous grinding activity.

Characteristics and kinetics study of simultaneous pyrolysis of microalgae Chlorella vulgaris, wood and polypropylene through TGA

Thermal decomposition behavior and kinetics of microalgae Chlorella vulgaris, wood and polypropylene were investigated using thermogravimetric analysis (TGA). Experiments were carried out at heating rates of 10, 20 and 40°C/min from ambient temperature to 600°C. The results show that pyrolysis process of C. vulgaris and wood can be divided into three stages while pyrolysis of polypropylene occurs almost totally in one step. It is shown that wood can delay the pyrolysis of microalgae while microalgae can accelerate the pyrolysis of wood. The existence of polymer during the pyrolysis of microalgae or wood will lead to two divided groups of peaks in DTG curve of mixtures. The results showed that interaction is inhibitive rather than synergistic during the decomposition process of materials. Kinetics of process is studied by the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The average E values obtained from FWO and KAS methods were 131.228 and 142.678kJ/mol, respectively.