Abstract: Vanadium phosphorus oxide (VPO) catalysts are the only industrial catalyst for the selective oxidation of n-butane. Doping with metal additives and modulation with organic additives are effective means to improve the performance of VPO catalysts. In this work, the simultaneous organo-metallic modification was achieved by adding magnesium chloride-alcohols deep eutectic solvents (MgCl2/alcohol) during the synthesis of VPO catalyst precursors. The VPO precursors and catalysts were analyzed by scanning electron microscope (SEM), BET automatic specific surface and porosity analyzer (BET), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), Raman spectrometer (Raman) and X-ray photoelectron spectroscopy (XPS), et al. The effect of deep eutectic solvents with different hydrogen bond donors about ethylene glycol (EG), 1-4 butanediol (BDO), and glycerol (GL) on VPO catalysts was investigated. The microscopic morphology, specific surface area, physical phase, surface properties, and crystalline phase transition temperature of VPO precursors as well as catalysts were analyzed in detail. The performance of VPO catalysts was evaluated in the fixed bed reactor for n-butane oxidation selectivity to maleic anhydride. The results showed that the introduction of deep eutectic solvent MgCl2/EG in the synthesis of VPO catalyst precursors can modulate the morphology and crystalline phase composition, thus improving the catalyst performance. The use of MgCl2/EG to modulate the preparation of VPO precursors can obtain catalysts with better dispersion, larger specific surface area, the highest total acid, and a number of active surfaces. VPO-MgCl2/EG catalysts had good dispersion, large specific surface area, a high number of active surfaces (020), enrichment of surface P atoms, and low average valence state of surface V. Furthermore, (VO)2P2O7 and VOPO4 crystalline phases synergistically improved the performance of VPO-MgCl2/EG catalysts. In conclusion, VPO-MgCl2/EG exhibited excellent catalytic performance in the reaction of n-butane oxidation selectivity to maleic anhydride, which provides a new idea for the preparation of VPO catalysts.

Key words: VPO catalysts, alkaline earth metal-alcohols deep eutectic solvents, preparation, characterization, catalyst performance

摘要： 钒磷氧(VPO)催化剂是目前实现正丁烷选择性氧化的唯一工业催化剂。利用金属助剂掺杂以及有机助剂强化是提高VPO催化剂性能的有效手段。本工作通过加入氯化镁醇类金属低共熔溶剂，实现了有机-金属助剂同时对VPO催化剂性能的调控。利用扫描电子显微镜(SEM)、BET全自动比表面与孔隙度分析仪(BET)、X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)等表征手段，深入探讨了合成过程中加入不同氢键供体乙二醇(EG)、1-4丁二醇(BDO)和甘油(GL)的低共熔溶剂对VPO催化剂微观形貌、比表面积、物相、表面性质和晶相转变温度的影响，同时利用固定床反应器对VPO催化剂催化正丁烷氧化制备顺酐的性能进行了评价。结果表明，氯化镁乙二醇低共熔溶剂调控制备的VPO催化剂具有分散性良好、比表面积大、活性面(020)的数量多、表面P原子富集和表面V平均价态低等特点，在丁烷氧化选择性制顺酐反应中表现出了良好的催化性能，为VPO催化剂的制备提供了新思路。

关键词: VPO催化剂, 碱土金属醇类低共熔溶剂, 制备, 表征, 催化剂性能