Chlorine Release from Co-Pyrolysis of Corn Straw and Lignite in Nitrogen and Oxidative Pyrolysis

Elevated emissions of hydrogen chloride (HCl) from the combustion of biomass in utility boilers are a major issue because they can cause corrosion problems and deposit molten alkali chloride salts on boilers’ water tubes, resulting in further corrosion. Pyrolysis is a good pre-treatment for solving this problem. This work conducted pyrolysis and co-pyrolysis of pulverized corn straw and lignite coal in a horizontal muffle furnace, with compositions typical of power plant combustion effluents (5% O2, 15% CO2, 80% N2) at different temperatures. Cl compounds were monitored in fuel, flue gas, and solid production of pyrolysis. The co-pyrolysis significantly affected Cl release from fuel. Cl release from corn straw into fuel gas was reduced during biomass co-pyrolysis with lignite. Co-pyrolysis had little influence on the release of organic Cl and KCl. Furthermore, at moderate-temperature pyrolysis, O2 promoted HCl release, when compared with pyrolysis under a N2 atmosphere.

In-depth temperature and smoke production of charring wood under a constant external heat flux

The combustion characteristics of charring wood have been studied experimentally in a well-ventilated environment of a smoke chamber. A numerical simulation has also been performed for a limited case, with the Fire Dynamics Simulator, to estimate the burning environment. A horizontally placed specimen (ponderosa pine) with a moisture content of 0% or 20% is exposed to a radiant flux (25 kW/m2), with or without flaming ignition. Simultaneous measurements of the specimen’s in-depth temperature and the mass loss determine the charring front (rate) at 300 °C and the gasification rate, respectively. These condensed-phase conditions relate directly to real-time variations of gas-phase quantities: the specific optical density of smoke and the concentrations of toxic gases measured by a Fourier transform infrared gas analyzer. In-depth temperature trends are similar whether the flame exists, whereas the smoke and toxicants’ concentrations are substantially different. After the charring front moves through the specimen, the oxidative pyrolysis continues under the irradiation at high temperatures (up to ∼550 °C). Carbon monoxide and acrolein are produced continuously throughout the test, and the results indicate strong correlations. Although char formation of wood is favorable for fire safety, consequent incomplete combustion produces smoke and toxicants.

Obtaining a diesel fuel component from liquid products of oxidative pyrolysis of wood

Recycling and rational use of wood-processing industry waste is an urgent task for the economy and industry. On the basis of experimental studies on the oxidative pyrolysis of Siberian pine and Downy birch, a basic technological scheme for components of motor fuels obtaining is proposed. It is shown that the main components of liquid products of wood pyrolysis in water vapor are aromatic and saturated hydrocarbons, as well as oxygen-containing compounds that need to be hydrogenated.

Thermal Oxidative and Non-Oxidative Degradation Behaviour of Afuze Coal

This study presents a preliminary analysis of the chemical and thermal fuel properties of Afuze (AFZ) coal extracted from coalfields in Owan East Local Government Area of Edo State, Nigeria. The chemical properties of AFZ were examined by combined scanning electron microscopy-energy dispersive X-ray (EDX), whereas the thermal properties were deduced by thermogravimetric analysis (TGA) under flash (50 °C/min heating rate) oxidative (combustion) and non-oxidative (pyrolysis) conditions. The microstructure and morphology analysis of AFZ revealed has a compact structure comprising small-to-large, irregular shaped and exfoliated grains with a vitreous appearance typically ascribed to metal elements (Ti and Fe) kaolinite, quartz, and other clay minerals. Chemical analysis revealed carbon, oxygen, aluminium, silicon, sulphur, calcium, titanium, and iron in major and minor (trace) quantities. Thermal analysis under oxidative and non-oxidative conditions revealed degradation occurs in three stages, namely; drying or demineralisation, devolatilization or maceral degradation and the formation of char/coke or ash. Lastly, the findings showed that the temperature range for the oxidative thermal degradation process (338.58 - 756.76 °C) was higher than the non-oxidative process (378.43 - 615.34 °C). This observation can be explained by the exothermic nature of the oxidative (combustion) process, which ensures greater heat supply required to thermally soften or degrade the maceral coal components. Overall, the oxidative process yielded the residual mass (RM = 21.97%) and mass loss (ML = 78.03%). The lower ML (49.03%) but higher RM (50.97%) observed during non-oxidative degradation of AFZ could be ascribed to the largely endothermic nature of the process.

Synthesis and Study of the Properties of Photocatalytic Compositions Based on Sro/Bi2O3 and (Bio)2CO3 Solid Solutions with Modifying Additives of Transition Metals Cu, Mn, Fe

In this work, we studied the effect of doping with d metals (Me: Mn, Fe, Cu) on the photocatalytic activity and optical properties of the hetero-structured, bismuth-containing Sr1-xMexBi4O7 / (BiO)2CO3 photo-catalyst, where x = 0.01–0.05. The stages of oxidative pyrolysis of precursor organometallic complexes with sorbitol by differential scanning calorimetry have been studied. The first stage of oxidative destruction is induced by the influence of nitrate-ion and terminates at temperatures below . The second stage of pyrolysis is associated with a further thermal degradation of sorbitol to pyrolytic carbon in the temperature range 113 - . The third stage 287–462°C is associated with the combustion of the formed pyrolytic carbon. The final stage of pyrolysis occurs in the temperature range of 462-with the formation of the target synthesis products. It has been established that Cu is the most effective dopant. In contrast to other metals, doping with copper results in the formation of a solid solution in the CuO-SrBi4O7 system. Compared to the initial SrBi4O7, as a result of doping Cu in an amount of 5 at. % the largest change in the band gap from 2.77 to 2.62 eV is achieved. The efficiency of photo-catalysis (estimated by the half-conversion of methylene blue) of the Cu0.05Sr0.95Bi4O7 / (BiO) 2CO3 composition turned out to be 2.3 times higher than the initial - undoped catalyst; and 3.1 times higher than in the non-catalytic process.

An Efficient Strategy for Enhancing the Adsorption Capabilities of Biochar via Sequential KMnO4-Promoted Oxidative Pyrolysis and H2O2 Oxidation

In this study, sequential KMnO4-promoted oxidative pyrolysis and H2O2 oxidation were employed to upgrade the adsorption capacities of durian shell biochar for methylene blue (MB) and tetracycline (TC) in an aqueous solution. It was found that the KMnO4/H2O2 co-modification was greatly influenced by pyrolysis temperature and the optimal temperature was 300 °C. Moreover, a low concentration of H2O2 enabled the improvement of the adsorption capabilities greatly with the catalysis of pre-impregnated manganese oxides, addressing the shortcoming of single H2O2 modification. The co-modified biochar exhibited high adsorption capabilities for MB and TC, remarkably surpassed KMnO4- and H2O2- modified biochars as well as pristine biochar. The increase of adsorption capabilities could be mainly contributed to the incorporation of MnOx and carboxyl by KMnO4-promoted oxidative decomposition and Mn-catalyzed H2O2 oxidation. This would provide a novel and efficient method for preparing highly adsorptive biochar using sequential KMnO4-promoted oxidative pyrolysis and H2O2 oxidation.