Abstract:

A series of hydrotalcite nanosheets with different Mg content were in-situ constructed on the surface of Al₂O₃ support by one-step synthesis method. And promoter In and active component Pt were introduced in the nanosheets by consecutive impregnation-reconstruction method. Furthermore, the supported Pt-In bimetallic catalysts PtIn/HTR-x (x = 0.05, 0.1, 0.15, 0.2 mol·L^-1) were prepared by calcination and reduction. The relationship between the structure, physical and chemical properties of the catalyst and its precursor and the direct dehydrogenation performance of isobutane was explored. The results show that the Mg²⁺ concentrations determine the nanosheets thickness, which affects the structure, reducibility, surface chemical states, and surface acidity and dehydrogenation properties of these catalysts. The catalyst with Mg²⁺ concentration of 0.15 mol·L^-1 exhibits the optimum dehydrogenation performance, of which the isobutene yield reaches 58%. The excellent activity, selectivity and stability of PtIn/HTR-0.15 are attributed to the maximum specific surface area, strong metal-support interaction and high surface In³⁺/In⁰ atomic ratio, and the good anti-carbon deposition performance is related to the low concentration and weak strength of surface strong acid sites.

Key words: isobutane, dehydrogenation, catalyst, hydrotalcite nanosheets, Mg concentration, carbon deposition

摘要：

采用一步法在Al₂O₃表面原位生长一系列Mg含量不同的超薄水滑石纳米片，并采用分步浸渍复原法逐步引入助剂In和活性组分Pt，进一步通过焙烧和还原处理制备了负载Pt-In双金属催化剂PtIn/HTR-x(x = 0.05，0.1，0.15，0.2 mol·L^-1)。探究了催化剂及其前体的结构、物化性能与异丁烷直接脱氢性能之间的关系。结果表明，制备母液中Mg²⁺浓度会影响纳米片厚度，进而影响催化剂结构、还原能力、表面化学状态、表面酸性和脱氢性能。当Mg²⁺浓度为0.15 mol·L^-1时，催化剂获得最佳脱氢性能，其中异丁烯产率高达58%。催化剂PtIn/HTR-0.15优异的活性、选择性、稳定性及良好的抗积炭性能与催化剂高的比表面积、低的强酸量和酸强度、强的金属载体相互作用以及高的表面In³⁺/In⁰原子比有关。

关键词: 异丁烷, 脱氢, 催化剂, 水滑石纳米片, Mg浓度, 积炭