Papers by Keyword: Pyrolysis

Abstract: A facile method was developed to synthesize amorphous carbon coated nano-sized silicon and graphite by using glucose or pitch as organic carbon source, nano-sized silicon particles were uniformly coated onto the artificial graphite by combined ball milling and spray drying pyrolysis, and the effect of binder types, binder amounts on the precursor morphology, feed rate and spray pressure on the electrochemical performance were investigated in detail. The partial size, surface morphology and electrochemical performances of the as-synthesized powders were analyzed by particulate size description analyzer (PSDA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and constant current charge/discharge tools. It is found that, citric acid and binder are important for improving the free-aggregation of nano-sized silicon and the morphologyof combined silicon and graphite. Therefore, under the optimal experimental conditions, amorphous carbon from pitch coated nano-sized silicon and graphite composite anodes exhibits much higher electrochemical performance. It can deliver the first discharge specific capacity of 796.3mA·h/g at a current density of 100 mA/g, as well as 85% of initial coulombic efficiency. Additionally, the discharge specific capacity retains 724.9mA·h/g, and the discharge capacity retention of a half cell system is 91% after 50 cycles.

Abstract: Biological treatment of municipal and industrial wastewater becomes more common in EU countries. As a result, the amount of wastewater sludge increases. The political and economic situation in world is requiring new methods for recovery of non-renewable mineral resources. Sludge is great secondary source of many elements. The aim of this research is to summarize available techniques for sustainable utilization of industrial sludge and recovery of critical raw minerals (CRMs). The most common sustainable method is using treated sludge as fertilizer in agriculture due to high content of P, N, C and microelements. However, this method has many restrictions, e.g. it can contain toxic substances or lack of appropriate land. Thermal sludge treatment methods like pyrolysis have developed crucially in last decade and pyrolysis units for sludge treatment are commercially available now. Pyrolysis becomes the most sustainable method due to recovery of CRMs and better energy recovery comparing to incineration.

Abstract: Devonian, and Quaternary clays of Latvia together with additive of sawdust after plastic moulding of pellets were used. Partial oxidation of sawdust and formation of active carbon after thermal shock at temperature 800°C were determined. The main clay mineral in all of clays was hydromica with some difference in the structure. Obtained materials with bulk density 1.1 g/cm³ as sorbent for different chemicals such as iodine and methylene blue was used. Dependence of sorption ability of pellets on the type of used clay (clay minerals) was determined. XRD for the determination of phase compositions, nitrogen absorption for the pore size distribution, SEM for the analysis of structure and nanoscale Zetasizer for the determination of surface charge were used.

Abstract: The chemical synthesis is a leading route for the purposeful design of nanomaterials, whereas the tungsten oxides are employed in a variety of special applications. The production of nanomaterials by traditional synthetic methods is still a cumbersome multistep procedure. Here we propose an improved method to produce tungsten oxide nanoparticles via a pyrolytic process. A tungsten-containing precursor was prepared by liquid extraction using n-trioctylamine (C₈H₁₇)₃N solution in toluene. We have shown that the conditions of thermal treatment of the W-based precursor determine the crystalline structure and nanomorphology of the final product. Monoclinic WO₃ nanocrystallites are produced conducting the pyrolysis above 450 °C. The proposed method is a facile and versatile route to produce and control the phase composition and morphology of tungsten oxide-based nanomaterials.

Abstract: Palm oil is considered as a potential feedstock for biofuel production in Thailand due to its property and availability. In recent years, there has been an increased attention on upgrading of palm oil to biofuels using various technologies. One of the most promising technologies is pyrolysis, in which palm oil is heated at the temperature in the range of 400 to 500 °C under oxygen-free atmosphere. In the present study, the uncoated catalyst and coated catalyst pyrolysis processes of palm oil for biofuel production in a continuous flow microchannel reactor were investigated with various catalyst types (MgO, Al₂O₃) at 400-500 °C, 2 ml/hr palm oil flow rate, and 0.1 g of catalysts. Liquid product yield, solid product yield and gaseous product yield were determined. The obtained results revealed that the high triglyceride conversion could be achieved at a short reaction time in microchannel reactor, which attributed to the enhancement of both heat and mass transfer. The pyrolysis liquid products composed of hydrocarbons, free fatty acids, and other oxygenated compounds which are the results of triglyceride cracking. Furthermore, product selectivity of palm oil pyrolysis depended on temperature and catalyst type.

Abstract: The fundamental objectives of this study is to analyzed and compare the physical and chemical properties of pyrolysis products (biochar and bio-oil) derived from two oil palm wastes. Empty fruit bunch (EFB) and mesocarp fibre (MF) were subjected to pyrolysis at a temperature of 400 °C for 2 hours holding time at 10 °C/min heating rate and with nitrogen flow rate of 2 L/min. The result obtained from raw material showed that MF contains a high quantity of hemicellulose and lignin which led to a high yield of bio-oil and biochar respectively, whereby, EFB contained a high content of cellulose. The high content of cellulose in EFB resulted in a high yield of gas compared to fibre. The higher heating value (HHV) of biochar and bio-oil were found to be 28.76 and 19.45 MJkg^-1 for MF and, 24.33 and 19.98 MJkg^-1 for EFB, respectively. Comparatively, the biochar obtained from MF material has high HHV than EFB material. However, all the biochars derived can be used for briquettes production as coal replacement in the future due to significantly high calorific value as compared to Malaysian sub-bituminous coal which has 24.6 MJkg^-1. Furthermore, pyrolysis of any wastes encourages proper sanitation and lead to a healthy environment. It can also serve as a potential solution to the energy crisis in developing countries, Nigeria in particular if bio-oil can be improved to power electricity generation facilities in replacement to diesel.

Abstract: Carbon fibre reinforced carbon composites (C/C) are characterised by their excellent thermal, chemical and mechanical properties. The intrinsic porosity and fibre reinforcement grant them an excellent damage tolerance. The production of complex structures is time consuming and very expensive. An innovative approach to this topic is the integration of simple geometric ceramic composite materials within complex polymer structures. The motivation of this contribution is to investigate the influence of hexamethylenetetramine as hardener (hardener content: 4, 8, 12 and 16 %) and curing parameters (tempered and non-tempered) on the microstructure and mechanical properties of the porous C/C composites. During the course of this contribution, selected carbon fibre reinforced polymer (CFRP) composites with different porosities were produced while adjusting the resin or hardening agent-ratio, as well as the processing parameters. Subsequent to the curing of the CFRP samples, porous C/C composites were produced by means of a pyrolysis process. The final part of the contribution is comprised of the microstructural analysis by light microscopy and the explanation of the flexural strengths, by utilising a “three-point-bending test”.

Abstract: The main objective for an economic and ecological use of raw materials is the achievement of closed raw material cycles. Because of that, not only the manufacturing procedures are important during the development of new materials but also the recycling processes. Within the increased use of lightweight construction in recent years, the application of multi-material or hybrid structures reach high significance for the automotive industry. In this development, especially the carbon fibre reinforced plastics (CFRP) gained its importance. However, currently there are no recycling strategies available for hybrid structures; complete recycling processes for CFRP are still expandable. This work presents methods for separation of hybrid structures made of metal and CFRP, as well as the corresponding process windows and the boundary conditions. The separation is performed by introduction of thermal heat and the behaviour of these bonded compounds is analyzed based on shear tensile tests. The results of these studies are used to develop a complete recycling process for reclamation of hybrid structures.

Abstract: In view of the constant search for new sources of renewable energy, the particulate agro-industrial waste reuse emerges as an advantageous alternative. However, despite the advantages of using the biomass as an energy source, there is still strong resistance as the large-scale replacement of petroleum products due to the lack of scientifically proven efficient conversion technologies. In this context, the pyrolysis is presented as one of the most widely used thermal decomposition processes. The knowledge of aspects of chemical kinetics, thermodynamics these will, heat and mass transfer, are so important, since influence the quality of the product. This paper presents a kinetic study of slow pyrolysis of coffee grounds waste from dynamic thermogravimetric experiments (TG), using different powder catalysts. The primary thermal decomposition was described by the one-step reaction model, which considers a single global reaction. The kinetic parameters were estimated using nonlinear regression and the differential evolution method. The coffee ground waste was dried at 105°C for 24 hours. The sample in nature was analyzed at different heating rates, being 10, 15, 20, 30 and 50 K/min. In the catalytic pyrolysis, about 5% (w/w) of catalyst were added to the sample, at a heating rate of 30 K/min. The results show that the one-step model does not accurately represent the data of weight loss (TG) and its derivative (DTG), but can do an estimative of the activation energy reaction, and can show the differences caused by the catalysts. Although no one can say anything about the products formed with the addition of the catalyst, it would be necessary to micro-pyrolysis analysis, we can say the influence of the catalyst in the samples, based on the data obtained in thermogravimetric tests.

Abstract: The lignocellulosic biomass is a renewable alternative for fossil fuels. The extensive cultivation of coffee grounds in Brazil generates a large amount of residues, as coffee husks. The work aimed at performing the coffee husks characterization, investigating the viability for fast pyrolysis application. Coffee husks were dried, grinded in a knives mill and sieved using a mechanical sieving; different vibration frequencies and times were used to evaluate the effect of these variables in the size distribution. The true density was inferred for three distinct size ranges of the coffee husks, using a helium pycnometer. Proximate and ultimate analyses were performed. The analytical pyrolysis was realized at 550°C, using a micro pyrolyzer (CDS 5200), vapors was identified by a gas chromatograph and a mass spectrometer (GC-MS QP 2010 plus, Shimadzu). The influence of the particles irregular shape was evidenced in the results of size distribution. The values of true density were around 1.5 g/cm³. The smaller the particle size, the higher the true density of the sample. Coffee husks can be used to generate high added value compounds: 1,3 pentadiene, limonene and n-hexadecanoic acid. Considering the use of coffee husks bio-oil as a fuel, results indicated that the bio-oil will present high calorific value, important acidity and smaller increases in viscosity and molecular weight if compared to the bio-oil of other lignocellulosic materials.