The organic and mineral components in two coals and resulting high-temperature ashes with high silicon content were characterized by second-derivative infrared spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). The infrared spectra of raw coals show weak organic functional groups bands but strong kaolinite bands because of the relatively high silicates content. In contrast, the Raman spectra of raw coals show strong disordered carbon bands but no mineral bands since Raman spectroscopy is highly sensitive to carbonaceous phases. The overlapping bands of mineral components (e.g., calcite, feldspar, and muscovite) were successfully resolved by the method of second-derivative infrared spectroscopy. The results of infrared spectra indicate the presence of metakaolinite in coal ashes, suggesting the thermal transformation of kaolinite during ashing. Intense quartz bands were shown in both infrared and Raman spectra of coal ashes. In addition, Raman spectra of coal ashes show a very strong characteristic band of anatase (149 cm^–1), although the titanium oxides content is very low. Combined use of second-derivative infrared spectroscopy and Raman spectroscopy provides valuable insight into the analyses of mineralogical composition. The XRD results generally agree with those of FTIR and Raman spectroscopic analyses.

Perovskites with flexible structures and excellent redox properties have attracted considerable attention in industry, and their denitration activities can be further improved with metal substitution. In order to investigate the effect of Ce and Cu substitution on the physicochemical properties of perovskite in NH₃-SCR system, a series of La_1−xCe_xMn_1−yCu_yO₃ (x = 0, 0.1, y = 0, 0.05, 0.1, 0.2, 0.4) catalysts were prepared by citrate sol-gel method and employed for NO removal in the simulated flue gas, and the physical and chemical properties of the catalysts were studied using XRD, SEM, BET, XPS, DRIFT characterizations. The Ce substitution on A-site cation of LaMnO₃ can improve the denitration activity of the perovskite catalyst, and La_0.9Ce_0.1MnO₃ displays NO conversion of 86.7% at 350 °C. The characterization results indicate that the high denitration activity of La_0.9Ce_0.1MnO₃ is mainly attributed to the larger surface area, which contributes to the adsorption of NH₃ and NO. Besides, the appropriate Cu substitution on B-site cation of La_0.9Ce_0.1MnO₃ can further improve the denitration activity of perovskite catalyst, and La_0.9Ce_0.1Mn_0.8Cu_0.2O₃ displays the NO conversion of 91.8% at 350 °C. Although the specific surface area of La_0.9Ce_0.1Mn_0.8Cu_0.2O₃ is lower than La_0.9Ce_0.1MnO₃, the Cu active sites and the Ce³⁺ contents are more developed, making many reaction units formed on the catalyst surface and redox properties of catalyst improved. In addition, strong metal interaction (Ce⁴⁺ + Mn²⁺ + Cu²⁺ ↔ Ce³⁺ + Mn³⁺/Mn⁴⁺ + Cu⁺) and high concentrations of chemical adsorbed oxygen and lattice oxygen both strengthen the redox reaction on catalyst surface, thus contributing to the better denitration activity of La_0.9Ce_0.1Mn_0.8Cu_0.2O₃. Therefore, appropriate cerium and copper substitution will markedly improve the denitration activity of La–Mn perovskite catalyst. We also reasonably conclude a multiple reaction mechanism during NH₃-SCR denitration process basing on DRIFT results, which includes the Eley–Rideal mechanism and Langmuir–Hinshelwood mechanism.

Probable surface NH₃-SCR reaction mechanism over CuCe/TiO₂-ZrO₂ catalyst is proposed to follow the E–R mechanism and the L–H mechanism, while the E–R mechanism dominates in the reaction and the oxidation of NO closes the catalytic cycle.

This paper aims to investigate the evolution of the chemical structure of coal char during pyrolysis. Two bituminous coals (coals A and B) and one lignite (coal C) were pyrolyzed in a fixed bed in N₂ from 600 °C to 1100 °C. The chemical structure of coal char was characterized by Raman spectroscopy and X-ray diffraction (XRD). The carbon and oxygen functionalities of coal char were analyzed by X-ray photoelectron spectroscopy (XPS). The Raman spectroscopic parameters A_D/A_G (A_D1/A_G, A_D2/A_G, and A_D3/A_G) increased from 600 °C to 900 °C and then decreased after 900 °C, indicating that the degree of order of coal char first decreased and then increased with increasing pyrolysis temperatures (600–1100 °C). The content of graphite-like microcrystalline carbon decreased and then increased with an increase in temperature. Prominent diffraction peaks of microcrystalline carbon for coal chars A and B were observed, but only minerals were shown in diffraction patterns of coal char C since the ash content of coal chars A and B is much lower that that of coal char C. The lateral size of the crystallite plane (L_a) generally increased between 600 °C and 1100 °C. The relative content of C=O and COOH in coal chars A and B generally decreased as the temperature increased, suggesting an increase in the degree of order at higher temperatures. The oxygen functionalities of coal char were composed of organic oxygen and oxygen-containing bonds of minerals.