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Plastic waste is causing serious environment pollution and its efficient disposal is attracting more and more attention. The use of catalysts not only reduced the degradation temperature of plastic wastes but also facilitated the production of valuable chemicals. Herein, mesopores were introduced into HZSM-5 zeolites by alkali and acid treatment, which was expected to eliminate the diffusion resistance caused by bulky polymer molecules and improve the catalytic activity. It was found that HZSM-5 zeolites enhanced PE, PP and PS degradation, and an increase of mesopore volume further improved the catalytic activity and reduced the activation energy. For example, the use of HZSM-5 in PP degradation decreased the activation energy from 146.9 kJ mol−1 to 93.1 kJ mol−1, and mesopore-rich HZSM-5 further decreased the activation energy to 84.0 kJ mol−1. The molecular diameter of the PP fragment was obtained by theoretical calculations, and it was close to 1.6 nm, which was significantly higher than the micropore diameter of HZSM-5 zeolites (0.5–0.6 nm) while lower than the mesopore diameter. It was concluded that the presence of mesopores provided the place and space for plastics degradation. [ABSTRACT FROM AUTHOR]

In this work, the effects of ethanol on n-heptane catalytic cracking over HZSM-5 zeolites were explored at 550 °C for 6 h on stream. Particular attention was paid to the measurement of product distribution, especially alkene and aromatic products. Due to the unique structure, ethanol easily interacts with the acid sites over HZSM-5 zeolites. It favored the dehydration to ethene formation and prevented alkene secondary reaction to aromatic formation. Thus, ethanol addition promoted alkene selectivity while reducing aromatic selectivity in n-heptane catalytic cracking. However, ethanol addition accelerated the deactivation of HZSM-5 zeolites. XRD, 27Al MAS NMR, TG-DSC, N2 adsorption–desorption, and NH3-TPD were employed to characterize the fresh and spent HZSM-5 zeolites and elucidate the roles of ethanol in coke formation and HZSM-5 deactivation during n-heptane catalytic cracking. It was found that alkene promotion caused by ethanol addition enhanced coke formation and its migration from the micropores to the external surface of HZSM-5 zeolites. The formation and accumulation of external coke sharply blocked the pore openings and reduced the accessibility of the acidic site, accelerating HZSM-5 deactivation. Moreover, ethanol was more harmful to the framework of HZSM-5 zeolites compared to n-heptane. It accelerated the collapse of HZSM-5 crystallite, which was negative to the catalytic performance. [ABSTRACT FROM AUTHOR]

LuVO4:Eu3+ nano/microcrystals with different morphologies/sizes including nanoparticles, nanosheets, nanodisks, nanoquadrangles, sub-microflakes, microspheres, and bulks were successfully synthesized by a mild solvothermal process using tartaric acid (TA) as the template. The amount of tartaric acid (TA) and the initial pH value play vital roles in controlling the morphologies of LuVO4 products. Besides, the reaction temperature was responsible for the generation of pure LuVO4 crystals in the presence of TA. Based on this, the possible formation mechanism of multi-morphologies was proposed. Furthermore, the dependence of luminescence performance on morphology has been discussed in detail. The LuVO4:Ln3+ (Ln = Tm3+, Er3+, Sm3+, Eu3+) nanoparticles show the characterized transition of Ln3+ and give bright blue, green, orange-red and red emission. Moreover, blue-green, green-yellow, pink, yellow-pink and white light can be obtained by adjusting the amount of doped Ln3+ ions and the corresponding concentrations of the LuVO4 host. This general and simple method may be of much significance in the synthesis of many other rare earth inorganic materials. [ABSTRACT FROM AUTHOR]

Single-atom site catalysts (SACs) have been used in multitudinous reactions delivering ultrahigh atom utilization and enhanced performance, but it is challenging for one single atom site to catalyze an intricate tandem reaction needing different reactive sites. Herein, we report a robust SAC with dual reactive sites of isolated Pt single atoms and the Ni 3 Fe intermetallic support (Pt 1 /Ni 3 Fe IMC) for tandem catalyzing the hydrodeoxygenation of 5-hydroxymethylfurfural (5-HMF). It delivers a high catalytic performance with 99.0% 5-HMF conversion in 30 min and a 2, 5-dimethylfuran (DMF) yield of 98.1% in 90 min at a low reaction temperature of 160 °C, as well as good recyclability. These results place Pt 1 /Ni 3 Fe IMC among the most active catalysts for the 5-HMF hydrodeoxygenation reaction reported to date. Rational control experiments and first-principles calculations confirm that Pt 1 /Ni 3 Fe IMC can readily facilitate the hydrodeoxygenation reaction by a tandem mechanism, where the single Pt site accounts for C[double bond, length as m-dash]O group hydrogenation and the Ni 3 Fe interface promotes the C-OH bond cleavage. This interfacial tandem catalysis over the Pt single-atom site and Ni 3 Fe IMC support may develop new opportunities for the rational structural design of SACs applied in other heterogeneous tandem reactions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)