High Stability of Ruthenium–Copper-Based Catalysts for Epoxidation of Propylene
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The catalytic performance of RuO2–CuO/SiO2-based materials for the direct gas-phase epoxidation of propylene using molecular oxygen at atmospheric pressure was investigated as a function of the Ru/Cu weight ratio and the addition of NaCl, TeO2, Cs2O, or TiO2. The best performing catalysts were then assessed for stability. Doping with NaCl delivered the highest PO yield, but its catalytic activity dropped quickly within a few hours due to the loss of chloride content. The same catalyst doped instead with TeO2, Cs2O, or TiO2 could maintain stable catalytic performance for 6 h. However, the addition of TeO2 presented the best improvement in terms of PO selectivity. Further optimization of PO selectivity for the RuO2–CuO–TeO2/SiO2 catalyst system was accomplished by varying reactor temperature and total feed gas flow rate. The highest PO selectivity could be achieved at 47% (255 gPO h−1 kgcat −1, 0.35% propylene conversion). The time-on-stream test revealed excellent catalytic stability within the 12 h of test period without any deactivation.
KeywordsCopper Epoxidation Propylene Propylene oxide Ruthenium, tellurium
This work was financially supported by Kasetsart University Research and Development Institute (KURDI), Center of Excellence on Petrochemical and Materials Technology, National Science and Technology Development Agency (NSTDA), Thailand Research Fund (TRF) and Commission on Higher Education (MRG5980240, IRG5980004).
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Conflict of interest
The authors declare no competing financial interest.