Peat Char Research Articles

Steam reforming of biomass tar model compound over two waste char-based Ni catalysts for syngas production

The removal of biomass tar is the key technology in the pyrolysis and gasification technology, and the advantages of solid waste pyrolysis char in tar removal gradually become prominent. In this paper, the tar model compound (benzene) was catalytic reformed by a novel hybrid carrier catalysts using a laboratory dual-stage reactor. The hybrid carrier catalyst was prepared by wet impregnation method with nickel active substance, and the carrier was a two-material mixture of peat char and sludge char. In the reaction of steam reforming benzene, the effects of temperature (600–800 °C) and nickel load (5%–20%) on benzene conversion were investigated, showing that the catalyst have good benzene removal ability (91.8%) and the gas product with high syngas content (93.6%) was obtained. The surface properties of the catalyst was detected by SEM, EDS, BET and XRD detection, in order to prove that the catalytic performance was related to surface nanoparticles and abundant active sites. The novel hybrid carrier catalyst can effectively remove the aromatic tar and produce syngas with high performance.

Catalytic toluene steam reforming using Ni supported catalyst from pyrolytic peat

The paper aims to investigate an effective method of catalytic reforming of toluene using peat char-supported Ni metal to achieve clean gas production. Utilizing KOH or CO2 activation to increases the surface area and pore volume of peat char during catalyst preparation. The chemical and structural properties of catalysts is explained based on SEM, EDS, XRD, BET method. Meanwhile, the influence of reaction temperature, residence times (τ), steam-to‑carbon ratios (S/C) in catalytic reaction and the molar ratio of CO, CO2, H2, CH4 in clean gas were investigated. The results indicated that SiO2 structure plays a significant role in nickel-based peat char catalyst, and the catalyst exhibited high catalytic performance. Conversion efficiencies of toluene can reach about 95.3% using Ni/APC catalyst at residence time of 0.5 s, steam-to‑carbon ratio of 3:1, temperature of 850 °C. The catalyst also exerted a positive effect on the syngas (CO + H2) production with the maximum molar ratio reaching up to 94.7 mol% under the optimized conditions. The high catalytic activity was mainly attributed to the structure of AlNi2Si and NiSi on the catalyst surface. Therefore, the cost-effective peat char-supported Ni catalysts could be used for aromatic tar conversion.

Synthesis and evaluation of pyrolysis waste peat char supported catalyst for steam reforming of toluene

Pyrolytic char as a catalyst carrier has been widely used in tar removal. This paper aimed to develop a cost-effective and eco-friendly tar steam reforming approach by using waste peat char supported Ca catalysts in a laboratory dual-stage reactor. Tar model compound toluene was used in steam reforming experiment for facilitate fundamental research. The reaction temperature, residence time, steam-to-carbon ratio and the molar ratios of H2, CO, CO2 and CH4 in the generated gas were investigated. Experimental results show that the peat char supported Ca catalysts had good selectivity for H2, especially the catalyst which activated by KOH and CO2. The catalyst demonstrated better catalytic activity with a higher residence time (0.6 s–0.7 s) and S/C ratio (S/C > 2.5). Under the optimized conditions, the toluene conversion and the mol% of H2 can reached 94.4% and 68.5%, respectively. Meanwhile, the activity of the catalyst was proved by a variety of performance tests, and the deactivation and mechanism of catalysts were investigated. Finally, these cost-effective and green peat char-supported Ca catalysts could be used for tar removal.

Reactivity and deactivation mechanisms of toluene reforming over waste peat char-supported Fe/Ni/Ca catalyst

The pyrolysis char from waste peat with impregnated metal (Fe/Ni/Ca) were investigated for catalytic reforming of toluene in a laboratory dual-stage reactor. The prepared catalysts were examined in microstructure and textural characterization to analyze catalytic performance and stability. The results indicated that under the optimized conditions, the toluene conversions are greater than 92.7% for three types of peat char-supported catalysts, and the maximum molar ratio of syngas (CO + H2) can reach up to 94.7% using Ni/peat char catalyst. The promising results demonstrated that the H2 and CO are favored for Fe/peat char and Ni/peat char catalysts while the H2 and CH4 are favored for Ca/peat char catalyst. After 320 min of experiment, the mol% of syngas decreased by less than 30% for three types of peat char catalysts. Significantly, peat char (C-SiO2) as a carrier can enhance the performance of catalyst through interaction with the metal, and it can be used as an adsorption carrier to absorb unreacted toluene. Such peat char-supported catalysts are thus promising for tar conversion and useful syngas production.

The effects of temperature on the activation of peat char in the presence of high calcium content

High calcium content peat was used for the preparation of activated carbons with CO 2 activation. The influence of temperature on the porous characteristics of the activated carbons was investigated. Calcium compounds were found to intensify the pore widening at high temperatures. As a result, the micropore volumes and surface areas of the samples prepared at 850 °C were lower than those prepared at 650 and 750 °C. As the mesopores were destroyed at high temperature, the total pore volume decreased at 850 °C and was lower than at 750 °C.

Effects of Ferromagnetic Inclusions on 13C MAS NMR Spectra of Heat-Treated Peat Samples

Peat char samples produced by heat treatments under inert atmosphere were characterized through 13C solid-state NMR, Mossbauer spectroscopy, and magnetization measurements. For samples prepared above 700 °C a set of strong spinning sidebands (SSB) were detected in NMR spectra acquired with direct polarization (DP) and magic-angle spinning (MAS), an effect that was shown to be consequence of the presence of ferromagnetic impurities associated with the mineral content of the studied peat samples. A detailed investigation on the nature and thermal transformations of the magnetic particles present in the natural and heat-treated peat samples was carried out by using magnetization measurements and Mossbauer spectroscopy. A pronounced increase in the ferromagnetic character of the heat-treated samples was verified from 600 °C upward, with the development of Fe3+ compounds, Fe3C, and Fe clusters. The effect of these ferromagnetic inclusions was the creation of magnetic field inhomogeneities throughout the sample...

Determination of optimal peat type to potentially capture copper and cadmium from solution.

The focus of this study was to determine the optimum type of peat for application as a medium to capture dissolved metals from aqueous solution. Seventeen media were examined, including eleven Irish peat samples from various locations and stages in processing, a Northern Ireland lignite, peat and lignite chars, a commercial-grade bone char, and two commercial-grade granular activated carbons. Considerable variation in sorption capacity was found with a ratio of 20:1 between the best-performing (bone char) and the poorest-performing (peat char) samples. Among the 14 varieties of peat, the best-performing sample outperformed the commonly investigated sphagnum moss by a ratio of 4:1. A correlation has been established between cation exchange capacity, the presence of adsorbed calcium, and the uptake capacity of different peats. This correlation will be a valuable tool in choosing peat type for filter media for metals removal applications.

13C High-Resolution Solid-State NMR Study of Peat Carbonization

Peat char samples produced by heat treatments under an inert atmosphere of nitrogen were characterized through 13C solid-state NMR, allowing the achievement of a detailed picture of the mechanism o...

98/01203 Characterization of gasification reactivity of peat char in pressurized conditions. Effect of product gas inhibition and inorganic material: Moilanen, A. and Muehlen, H.-J. Fuel, 1996, 75, (11), 1279–1285

98/01203 Characterization of gasification reactivity of peat char in pressurized conditions. Effect of product gas inhibition and inorganic material: Moilanen, A. and Muehlen, H.-J. Fuel, 1996, 75, (11), 1279–1285

97/01038 Characterization of gasification reactivity of peat char in pressurized conditions. Effect of product gas inhibition and inorganic material

97/01038 Characterization of gasification reactivity of peat char in pressurized conditions. Effect of product gas inhibition and inorganic material

Physical and chemical properties of a Brazilian peat char as a function of HTT

Physical and chemical properties of a Brazilian peat char as a function of heat treatment temperature (HTT) from 300 to 1000°C are reported. Powdered and compacted cylindrical samples of peat char were prepared at each HTT. The samples were characterized by ultimate analysis, proximate analysis, thermogravimetric analysis and measurements of dimensional changes, density, calorific value and electrical resistivity. The char has advantages over natural dried peat, such as higher calorific value and lower volatile matter. An advantage of the peat char studied in comparison with most wood charcoals is the higher apparent density (0.9 g cm −3) obtained for the compacted samples without any binding agent.

96/05899 Characterization of gasification reactivity of peat char in pressurized conditions. Effect of product gas inhibition and inorganic material

96/05899 Characterization of gasification reactivity of peat char in pressurized conditions. Effect of product gas inhibition and inorganic material

Characterization of gasification reactivity of peat char in pressurized conditions: Effect of product gas inhibition and inorganic material

The characteristic effects of the main operating parameters in pressurized fluidized bed gasification, such as pressure and product gas composition, and of inorganic material on peat char gasification reactivity were studied. The measurements were carried out isothermally in a pressurized thermobalance at temperatures between 1023 and 1233 K and pressures up to 1.5 MPa. Steam and carbon dioxide, both pure and mixed with the product gases H 2 and CO, were used as reaction agents. The reactivity was expressed in the form of instantaneous gasification rate vs. char burnoff. The steam gasification rate of peat char was only slightly higher than the CO 2 gasification rate, and the gasification rates decreased at increasing pressure in both steam and carbon dioxide. The steam gasification rate of the peat char increased to a maximum before decreasing with increasing char burnoff. In carbon dioxide, the main trend was that the gasification rate slightly increased with the burnoff. Demineralization of the peat decreased the reactivity and also removed the negative burnoff behaviour observed in steam gasification. The presence of the product gases H 2 and CO inhibited the gasification of the peat char almost entirely.

Burning characteristics of high-ash bangladeshi peat

The combustion characteristics of high-ash Bangladeshi peat was investigated in an atmospheric fluidized-bed combustor at bed temperatures of 750, 800 and 850°C. The particle size was varied from 8.05 mm to 22.76 mm. Combustion of this variety of peat occurred at constant size and thus followed a shrinking core model. Volatile evolution is complete before the particles reached bed temperature and during char combustion the particle temperature exceeded the bed temperature. Combustion times can be represented by power law equations. Results indicated that the burning rate of peat char is a combination of diffusion and kinetic control mechanisms.

Peat char reactivity in CO2 atmosphere at high pressures

AbstractReactivities of peat char have been measured in CO2–N2 gas mixtures at temperatures ranging from 600°C and 900°C and pressures of up to 9.1 MPa using a fixed bed placed in a flow reactor. A semi‐empirical kinetic expression is presented which includes the temperature, CO2 pressure and variation in the specific area of the substrate. An Arrhenius equation is used to obtain an activation energy of 99.1 kJ/mol for the gasification process.

Enhanced reactivity of metal-impregnated peat char and semi-coke during gas phase hydrogenolysis

Methane formation in the reaction between peat-derived chars and hydrogen was studied using peat semi-coke and doped chars. The latter were prepared by ion exchange of the initial material prior to pyrolysis. Impregnation with relatively large amounts of finely dispersed transition metals (up to ≈15 wt%) results in significant enhancement of methane production. Devolatilization prior to hydrogenolysis exerts a marked influence on the behaviour of the char due to its effect on the concentration of surface oxygen species. The lower the devolatilization temperature, the higher the methane yield. Two distinct peaks are present during the methane formation: a low-temperature peak involving the presence of CO and a high-temperature peak related to the direct reaction between H 2 and the char. The conversion profiles could be well approximated by a two-parameter model.

The influence of potassium carbonate on surface area development and reactivity during gasification of activated carbon by carbon dioxide

In this study it is shown that the uncatalysed gasification of activated peat char can be described by a reaction temperature independent increase of the specific surface area with increasing burn-off and a constant reactivity per unit surface area up to 60% burn off. Unlike nickel catalysis, potassium catalysis causes an increased microporosity due to microchanneling. Above ca. 0.6 atoms per nm 2 the increase of the reactivity per unit surface area with increasing burn-off can be described by a first order dependency with respect to the number of potassium atoms per unit surface area. This can be explained by assuming potassium intercalate formation to be an essential step. The development of microporosity appears to be more pronounced at higher reactivities and, consequently, at higher effective catalyst loadings and higher reaction pressures.