This work reports a novel method of combining both chemical activation and N₂ or steam post-treatment at high temperature for producing activated carbon (denoted as AC) used for the selective adsorption and separation of methane from the coal-bed gases. The used AC in the investigation mainly contained three kinds, commercial activated carbon (denoted as GH-8), the prepared activated carbon, denoted as AC-P, and AC-K, which was prepared by chemical activation using phosphoric acid and potassium hydroxide solution, respectively. Textural properties, surface oxygen-containing functional groups and methane adsorption performances of AC-P, AC-K, and GH-8 samples were comparatively investigated. Results demonstrated that both AC-P and AC-K showed higher methane adsorption capacity than the commercial activated carbon sample GH-8. Steaming treatment to AC-P at 800°C significantly enhanced the methane adsorption capacity to 6.5 mg/g, which was approximately two times higher than the commercial sample GH-8 (3.2 mg/g). The pronounced increment of adsorption capacity over AC-PS800 from steam-treatment was attributed to the significant increase of the area of micropores with a pore diameter of 0.45–0.65 nm. The presence of surface oxygen-containing groups on AC was proven to be slightly unfavorable to methane adsorption. CH₄ concentration in desorbed gas from AC-PS800 was drastically improved to about 70% in the effluent from about 5% in the feed gas, which demonstrated that the prepared AC-PS800 possessed high selective adsorption capacity for methane. These results would pay the way for concentrating and future utilization of methane in coal-bed gas.

NaCl-modified graphitic carbon nitrides (GCN) were applied in the base-catalyzed transesterification of recovered oil. GCN has been seen as a prospective heterogeneous catalyst for transesterification, but pristine-GCN has a narrow range of applications because of its weak basic sites and small surface area. To overcome these defects, NaCl-modified GCN was prepared through the co-thermal polymerization of NaCl with urea. The doping of NaCl generated C≡N and Na–N species, which enhanced the basicity of the catalyst. Meanwhile, with the assistance of NaCl, GCN was decomposed and produced a large number of small pores of hundreds of nanometers, which contributed to the increase in specific surface area. In addition, the effects of transesterification parameters and their interactions on biodiesel yields were investigated by using Box–Behnken design, and the reaction conditions were optimized. A high biodiesel yield of 93.05% was achieved under the optimal conditions.

The nitration reaction of aromatic compounds is one of the extensively studied chemical reactions that result in the manufacturing of various industrial products applied in pharmaceuticals, dyes, perfumes, and explosives. A series of modified sulfated zirconia (SZ) catalysts SO₄^2-/ZrO₂-M_xO_y (M=Ce, Co, Mn, Zn, and M/SZ) doped with different metal elements by a coprecipitation method were investigated in the toluene nitration reaction. Various characterization techniques (X-ray diffraction, Brunauer-Emmett-Teller, thermogravimetric analysis, X-ray photoelectron spectroscopy, and temperature-programmed desorption of ammonia) indicated that doping metal elements in SZ led to excellent catalytic properties, increasing the specific surface area of the catalyst and facilitating the formation of a stable tetragonal zirconia phase. Doping zinc and cobalt in SZ enhanced the acidity of the catalyst and formed stronger acidic sites, promoting the generation of nitronium ions and providing more active sites for the toluene nitration reaction. Additionally, it reduced the loss of sulfate ions in the catalytic system that helped in improving the stability of the catalyst. Under the same conditions, the catalytic activity of toluene nitration reaction demonstrated the following order: Zn/SZ > Ce/SZ > Co/SZ > Mn/SZ > SZ, with the zinc-doped SZ catalyst exhibiting the best catalytic performance, achieving a toluene conversion rate of 78.58% and a para/ortho nitrotoluene ratio of 0.67.