Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-33HPA-x + 2 H + + Pd 0 ⎯⎯→ Н m HPA-x + Pd II (5)Reaction (3) is many-stage too. Its completeness corresponding to minimal m red(3) valueincreases with rise of temperature and O 2 pressure [3]. Therefore, catalyst regeneration is tobe favorably performed at maximum possible temperature. However, catalysts based onKeggin-type HPA-x proved to be poorly thermally stable. At Т > 140°С, they began to yieldvanadium-containing deposits.In the course of optimization of the catalyst composition and conditions of the process,we have elaborated new catalysts in which high-vanadium Mo-V-phosphoric HPA solutionshaving non-Keggin-type composition H a P z Mo y V х’ O b (HPA-x’ zP where x’ ≥ 6, z = 2–4, y = 12–20, a = 2b - 6y - 5(x’+z)) are used [4]. Solutions of modified HPA-x’ can endure temperaturesup to 170°С for a long time without yielding deposits. The catalysts based on HPA-x’solutions have 3.5-fold greater productivity than the ones based on HPA-x solutions.Pilot tests for MEK-process with use of the (Pd + HPA-x’) catalyst have confirmed thatthe modified HPA-x’ solutions are really stable up to 170°С. At present time we look forpossibilities of additional stabilization of Pd in the reduced catalyst solution.References:1. Pat. 826603, Belgium, 1975 / Matveev K.I., Shitova N.B., Pai Z.P. et al.2. Zhizhina, E.G.; Simonova, M.V.; Odyakov, V.F.; Matveev, K.I. Appl. Catal. A: General 2007, 319, 91.3. Zhizhina, E.G.; Simonova, M.V.; Odyakov, V.F.; Matveev, K.I. Kataliz v Promyshlennosti 2005 (2), 17 (inRussian).4. Pat. 2243818, Russia, 2005 / Matveev K.I., Odyakov V.F., Zhizhina E.G., Balashov A.L., Fedotov A.V.366