By density functional theory (DFT), we report a detailed mechanistic study on the synthesis of methylacrolein (MAL) by a mild Mannich reaction of formaldehyde (FA) and propionaldehyde (PA) catalyzed by sec-amine short-chain aliphatic acid ionic liquids (ILs). ILs exhibit excellent catalytic activity and create mild reaction conditions (45 °C) by dramatically decreasing the reaction energy barrier (24.43 kcal mol −1 ) in the decomposition step of Mannich bases (MBs) comapred to without ILs. Three key intermediates observed by DFT calcutations were identified by electron spray ionization mass spectrometry (ESI-MS) analysis. We systematically investigated the catalytic effect of ILs with different sec-amines (HNR 2 , R = CH 3 , C 2 H 5 , etc.) on the activation energy and different short-chain aliphatic acids (RCOOH, R= H, CH 3 et al.) on the decomposition step of MBs. This work is intended to provide a thorough explanation of the synthesis mechanism of the mild Mannich reaction of MAL catalyzed by ILs from the theoretical aspect, which may give a favorable guidance for the practical application.

Water-wall entrained flow gasifiers ensure long-term safe operation using the idea of "fighting slag with slag". Thus, wall slagging is essential for the operation of gasifiers. The gasification process of dry coal power was simulated in the entrained flow gasifier by ANSYS Fluent software for this study. The eddydissipation concept model has been used to simulate the homogeneous reaction process in the gasifier. The unreacted core shrinking model has been used to simulate the heterogeneous reaction. The discrete phase model has been used to simulate the interaction between the gas phase and particles. The Yong model determines the adhesion of particles on the wall, and the Seggiani model describes the slag flow on the wall using a user-defined function compiler. The slag flow in the gasifier was simulated at an operating temperature of approximately 1750 K. The results show that the deposition flux of ash particles reaches a maximum value of 0.32 kg/m 2 s at 2.5 m below the gasification burner, and the deposition flux at the lower slag mouth remains at 0.08 kg/m 2 s. The maximum thickness of the liquid slag and total slag layers reach 14.4 and 62.7 mm, respectively.