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A series of Zn-modified HBeta (Zn/HBeta) catalysts were prepared via the wetness impregnation method with different zinc precursors such as ZnSO4·7H2O, ZnCl2, C4H6O4Zn·2H2O and Zn(NO3)2·6H2O, and their catalytic performance in the conversion of ethanol to propylene reaction was evaluated. Results indicate that the amount and strength distribution of the acid sites of the Zn/HBeta catalysts were easily tuned by employing different types of zinc precursors. More importantly, when the zinc species were introduced to the HBeta, the propylene yield was significantly enhanced, whereas the yields of ethylene and C2–C4 alkanes were remarkably suppressed. For the catalyst prepared by using the ZnCl2 precursor, a higher propylene yield of up to 43.4% for Zn/HBeta-C was achieved as a result of the moderate amount and strength distribution of acid sites. The average coking rate of the used Zn/HBeta catalysts strongly depended on the amount of total acid sites, especially the strong acid sites, i.e., the higher the amount of total acid sites of the catalyst, the greater the average coking rate. For the catalyst prepared by using the ZnSO4·7H2O precursor, Zn/HBeta-S exhibited a better stability even after depositing more coke, which was due to the higher amount of strong acid sites. [ABSTRACT FROM AUTHOR]

The NiO-MgO solid solution has been proven to be an efficient catalyst for the carbon dioxide reforming of methane (CRM). However, the challenge is still there for the facilely controlled synthesis of the single-phase solid solution with the uniform composition, and the interactions between NiO and MgO are not consistently correlated with the CRM performance. To address these issues, in this work, the complex-decomposition method was applied to regulate the chemical and structural properties of NiO-MgO catalysts via simply changing the complexing agent, calcination temperature, and Ni/Mg molar ratio. The catalysts were comparatively evaluated for CRM under severe reaction conditions of 750 °C, 0.1 MPa, CH4/CO2 = 1, and a gas hourly space velocity of 60000 mL·g−1·h−1. Irrespective of the complexing agents investigated, NiO-MgO solid solution was exclusively formed. However, the structural and reductive properties of the NiO-MgO catalysts were strongly dependent on the complexing agent, which is reasonably explained as the varied coordinative capabilities of the complexing agent with the metal cations. Moreover, the highest CRM performance, i.e., the initial CH4 conversion of ~86% kept constant for a time-on-stream of 20 h, was achieved over the Ni0.1Mg0.9O catalyst by using glycine as the complexing agent and calcined at 800 °C. The characterization and CRM results vigorously confirmed that a good balance between the sintering and the in situ release of active metallic Ni under CRM reaction conditions was constructed over the NiO-MgO catalyst prepared using glycine as the complexing agent, leading to its highest stability. Considering the simple procedure of the complex-decomposition method and the convenient adjustment of the NiO and MgO interactions by simply changing the complexing agent and calcination temperature, the thus developed catalyst can be applied for extensive understanding the CRM mechanism, and extended for large-scale preparation. [ABSTRACT FROM AUTHOR]