MAX phases exhibit a layer structure and unique characteristics that combine the high-temperature stability of ceramics and the good electrical properties of metals, attracting wide interest in catalysis. In this study, we prepared Ti₃AlC₂ MAX-supported V-based catalysts and investigated their catalytic performance in propane oxidative dehydrogenation and direct dehydrogenation reactions. The C₃H₈ conversion is approximately 8%, and the highest C₃H₆ selectivity exceeds 85% in oxidative dehydrogenation. Additionally, the initial conversion can reach 18% and the propene selectivity remains above 90% in propane catalytic dehydrogenation. Isolated VO_x species exhibit the highest intrinsic activity and the strongest resistance to inactivation. Oxygen vacancies with low-valence V sites in vanadium oxides are considered to be the active sites. Combining kinetic experiments, it is found that the oxidative dehydrogenation of propane follows a Langmuir–Hinshelwood (L–H) mechanism rather than the traditional Mars–van Krevelen (MvK) mechanism. A reaction pathway is reasonably proposed in which O₂ and C₃H₈ adsorb competitively and the reaction between adsorbed O₂ and C₃H₈ is the rate-determining step.

中文翻译：

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揭示 VOx/Ti3AlC2 丙烷脱氢机理


MAX相呈现出层状结构和独特的特性，结合了陶瓷的高温稳定性和金属的良好电性能，引起了催化领域的广泛兴趣。本研究制备了Ti ₃ AlC ₂ MAX负载V基催化剂，并研究了其在丙烷氧化脱氢和直接脱氢反应中的催化性能。氧化脱氢过程中C ₃ H ₈ 转化率约为8%，最高C ₃ H ₆ 选择性超过85%。此外，丙烷催化脱氢初始转化率可达18%，丙烯选择性保持在90%以上。分离的 VO _x 物种表现出最高的内在活性和最强的失活抵抗力。钒氧化物中具有低价V位点的氧空位被认为是活性位点。结合动力学实验发现，丙烷的氧化脱氢遵循Langmuir-Hinshelwood（L-H）机理，而不是传统的Mars-van Krevelen（MvK）机理。合理提出了O ₂ 和C ₃ H ₈ 竞争吸附以及吸附的O ₂ 与C反应的反应路径。 ₃ H ₈ 是速率决定步骤。