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This study aims to convert oily sludge (OS) into oily sludge char (OSC) by pyrolysis and microwave-induced pyrolysis. The operating parameters affecting the production of chars from OS by pyrolysis (temperature (200–800 °C) and residence time (30–150 min)) and microwave-induced pyrolysis (microwave power (200–800 W) and irradiation time (5–25 min)) were investigated. The tools used to identify the physiochemical properties of the best products were Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and thermogravimetric and derivative thermogravimetric analysis (TGA-DTG). Energy characteristics including higher heating values (HHV), proximate analysis, element composition, and H/C and O/C atomic ratios were explored. The OSC produced by pyrolysis at a temperature of 600 °C and residence time of 90 min (labeled as OSC-Py@600–90) achieved the highest HHV (22.95 MJ/kg), while the OSC produced by microwave at a microwave power of 800 W and irradiation time of 10 min (labeled as OSC-MW@800–10) achieved the highest HHV (28.33 MJ/kg). The BET surface area of OS, OSC-Py@600–90, and OSC-MW@800–10 are OS 29.56 m2/g, 81.33 m2/g, and 238.52 m2/g, respectively. The data of the current study clarified that the OSCs produced from OS by pyrolysis and microwave processes could be used for energy generation.

This study investigated the characteristics of NO emissions during oxy-coal combustion with wet-recycle, especially in the presence of high H2O concentrations. The oxy-combustion was carried out using two types of coal, namely Leiyang (LY) anthracite and Zhundong (ZD) bituminous coals, inside a 24 kW drop tube furnace under different O2/CO2/H2O atmospheres. The results showed that the NO conversion increased with decreasing CO2concentration from 70% to 30% and decreased with increasing H2O concentration from 10% to 40%. Under the experimental conditions employed in this study, the fuel-N conversion for both LY and ZD coals under the oxy-coal wet recycled combustion was lower than that under the oxy-coal dry recycled combustion. The results indicated that H2O and CO2showed a competitive effect on NO emissions, though both of them have positive effect on NO reduction. In order to investigate the effects of H2O/CO2on recycled NO, oxy-coal combustion experiments were also performed with the initial addition of NO concentrations of 900 ppmv. The results showed that NO reduction ratio in O2/CO2was lower than that in O2/CO2/H2O for both coals under our experimental conditions. It is believed that the results of this study can provide some fundamental information on the effect of H2O/CO2on the characteristics of NO emissions during oxy-coal combustion with wet-recycle.

Dry reforming of methane (DRM) promises to reduce greenhouse gas emission by converting CO2and CH4(produced e.g. in anaerobic digestion processes) into syngas with an almost equimolar H2/CO ratio suitable for use in Fischer–Tropsch (FT) synthesis for the production of varieties of high value chemicals and liquid fuels. Ni-based catalyst is the most viable catalyst to catalyse the reaction, but its use faces a great challenge due to its propensity to form and accumulate carbonaceous materials on its active surface. In this article, the mechanisms involved in the deactivation of Ni-based catalyst in DRM reaction by carbon deposition and other carbon-induced deactivation mechanisms, which understanding is vital for the improvement of the process, are reviewed. Based on a thorough assessment of literature, perspectives are given on ways to control and mitigate carbon deposition problems related to the use of Ni-based catalysts in DRM by means of manipulating reaction conditions and process parameters as well as through designing and developing the highly active coke-resistant Ni-based catalysts.