(454a) A Catalytic Membrane Reactor Configuration for the Direct Synthesis of Propene Oxide (PO) From Propene, Hydrogen and Oxygen

Propylene oxide (PO) is an important compound used in the chemical industry as intermediate for manufacturing of different products as polyether polyols, propene glycol, butanediol etc. However, the current main processes for PO production are considered to be environmentally unfriendly (chlorohydrin process), complex (hydrogen peroxide process) or lead to different and large amounts of undesired co-products with an important loss of the main component (hydroperoxide process). Alternative methods have been considered in order to overcome these problems and realise a sustainable and eco-friendly chemistry in accordance with the competitiveness of the industry’s policy. A first solution was presented by a single stage reaction for the direct synthesis of propylene oxide starting from hydrogen, oxygen and propene. The epoxidation reaction started to be performed on highly dispersed gold nano-particles on titania and then on titanium silicalite -1 (TS-1). The noble metal catalyzes the first step of the reaction (in situ hydroperoxy species generation) and TS-1 is responsible for the consecutive oxidation of propene. However, the application of this reaction is limited to excessive water formation and lower yields due to diluted reactants for safe operating conditions. An elegant way to address these problems is represented by a single engineering element as the catalytic membrane reactor. The catalytic membrane enabled a separate feeding of hydrogen and oxygen in order to avoid the formation of explosive regime and reduces direct water formation allowing for high concentrated gas mixtures with a high selectivity to PO.

In the present work a membrane configuration device is tested for the direct synthesis of propylene oxideover Au/Ti-SiO₂  catalyst. A key parameter as the thickness of the membrane was considered and related to the pressure drop in the reactor and rate product formation. The relationship between propylene oxide selectivity and propene feed configuration is analyzed in order to increase hydrogen efficiency. The optimal membrane reactor configuration concept can be presented after studying and combining the contribution of different parameters such as temperature, Au loading, reactant concentrations and flow rates.