Non-oxidative dehydrogenation of propane and isobutane over unconventional ZrO2- or TiO2-based catalysts: Understanding the role of coordinatively unsaturated metal cations

丙烷和异丁烷的非氧化脱氢为相应的烯烃是已建立的大规模方法，然而，该方法面临挑战，特别是在催化剂开发中，其是铬化合物的毒性和铂的高成本。为了应对这些挑战，该提案将涉及基于散装材料（ZrO 2和TiO 2）的环境友好型和成本效益型催化剂的开发。与典型的负载型催化剂相比，此类催化剂表面的晶格缺陷是催化活性中心。它们是位于氧空位的配位不饱和金属阳离子（Mecus = Zr或Ti）。在这个提议中要回答的主要基本问题是主体氧化物的影响（ZrO 2对TiO 2）和金属氧化物促进剂（例如K2 O、La 2 O3或CeO 2），用于在主体氧化物中产生阴离子空位，其影响（i）主体氧化物中表面Mecus的形成和（ii）活性，Mecus在丙烷和异丁烷脱氢中的运行稳定性和特别是选择性（包括焦炭形成）。从基础和应用两个角度选择烷烃。与丙烷/丙烯相比，异丁烷和特别是异丁烯（所需产物）可以分别异构化为正丁烷和直链丁烯。因此，阐明这些异构体是否可能为裂解产物和积碳的形成开辟另一条途径是很重要的。为了尽可能基本地了解催化剂功能的基本原理，我们将采用一种补充方法，将稳态和瞬态催化测试以及操作催化剂表征与密度泛函理论（DFT）计算相结合。特别地，该建议旨在i）建立结构-反应性-选择性关系，这是合理催化剂设计的关键因素，以及ii）为丙烯和异丁烯的最佳生产提供指导。所获得的知识将允许在节约自然资源和减少有害环境影响方面提高原材料功能化的效率。

Non-oxidative dehydrogenation of propane and isobutane to the corresponding olefins are established large-scale processes that, however, faces challenges, particularly in catalyst development, which are toxicity of chromium compounds and high cost of platinum. To address these challenges, this proposal will deal with development of environmentally friendly and cost-efficient catalysts based on bulk materials (ZrO2 and TiO2). In comparison with typical supported catalyst, lattice defects on the surface of such catalysts are the catalytically active sites. They are coordinatively unsaturated metal cations (Mecus = Zr or Ti) located at oxygen vacancies. The main fundamental questions to be answered in this proposal are the effects of the host oxide (ZrO2 vs TiO2) and the metal oxide promoter (e.g. K2O, La2O3, or CeO2) used for creating anion vacancies in the host oxides on (i) formation of surface Mecus in the host oxides and (ii) the activity, on-stream stability and particularly selectivity (including coke formation) of Mecus in dehydrogenation of propane and isobutane. The alkanes were chosen both from fundamental and applied viewpoints. In comparison with propane/propene, isobutane and particularly isobutene (the desired product) can be isomerized to n-butane and linear butenes respectively. Therefore, it is important to elucidate if such isomers may open another pathways for formation of cracking products and carbon deposits. In order to understand the fundamentals of catalyst functioning on a level as elementary as possible, we will follow a complementary approach combining steady-state and transient catalytic tests as well as operando catalyst characterization with Density Functional Theory (DFT) calculations. In particular, the proposal is intended i) to establish structure-reactivity-selectivity relationships, which are the key factor for rational catalyst design as well as ii) to provide guidelines for an optimal production of propene and isobutene. The knowledge derived would permit to improve the efficiency of functionalization of raw materials in terms of saving natural resources and reducing harmful environmental impacts.