Gas-Phase Epoxidation of Propylene with Hydrogen Peroxide Vapor: Effect of Modification with NaOH on TS-1 Titanosilicate Catalyst in the Presence of Tetra-propylammonium Bromide

Abstract

This study was related to a solvent-free gas-phase epoxidation of propylene with H2O2 vapor to synthesize propylene oxide (G-HPPO). Focus was given to the hydrothermal modification of TS-1 with NaOH–TPABr. Results showed that properly modified TS-1 exhibited 1.70 kgPO kgTS‑1 –1 h–1 propylene oxide productivity, 93.6% PO selectivity, and 12.9% propene conversion. More than 60 wt % H2O2 utility were achieved with a 4.7 propylene/H2O2 molar ratio. Catalyst characterizations indicated that considerable amount sodium ions were introduced into the modified TS-1. The infrared absorption feature of framework Ti was shifted to higher wavenumbers. The blueshift and the NH4 +-exchange experiment suggested that the modification changed the local environment of framework Ti by transforming them into “open” sites which had titanium hydroxyl groups and sodium ions on their neighboring silicon hydroxyls as counter cations. Unlike liquid-phase epoxidation, G-HPPO can be significantly benefit by the presence of the sodium ions in TS-1.

Solvent‐free gas‐phase epoxidation of propylene in fluidized bed reactor

“…In 2019, we showed how effective it is to inhibit the high‐temperature decomposition of H 2 O 2 on TS‐1 zeolitic catalyst by subjecting the catalyst into a controlled hydrothermal treatment with a solution of alkali metal hydroxide 6,7 . Specifically，when a large‐crystal TS‐1 zeolite was treated with a 0.1 mol/L NaOH solution (containing 0.05 mol/L TPABr), in the G‐HPPO reaction the catalyst (Na/Ti molar ratio ≈ 0.46) exhibited dramatically improved propylene conversion (12.9%), PO selectivity (93.6%) and H 2 O 2 utilization (60.6%) at 110°C and a C 3 H 6 /H 2 O 2 molar ratio 4.7, if was compared with 3.6%, 77%, and 16.9%, respectively, the large‐crystal, TS‐1 parent 6 . Interestingly, when the TS‐1 zeolite was hydrothermally treated by a plain solution of 0.1 mol/L NaOH, better catalyst (Na/Ti = 0.94) was obtained (H 2 O 2 utilization reached 79.3%) 7 .…”

“…To meet the requirement of the fluidized bed reactor, a microspheric TS‐1 (MsTS‐1) catalyst was developed based on an ultrafine nanometer TS‐1 zeolite. Besides, commercial H 2 O 2 manufactured by the anthraquinone process (0.5 g/g) rather than the electronic grade purity H 2 O 2 provided by the in site H 2 O 2 plasma reaction 6,7 was used as an oxidant. Results show that the fluidized bed G‐HPPO reaction has clear an advantage over the fixed bed G‐HPPO reaction with respect to the inhibition of H 2 O 2 decomposition.…”

Insight into the Effect of Copper Substitution on the Catalytic Performance of LaCoO3-Based Catalysts for Direct Epoxidation of Propylene with Molecular Oxygen

“…Recently, direct epoxidation of propylene to PO by the hydrogen peroxide (HPPO process) is able to achieve PO selectivity of above 90%. This process employs Au supported on titanium silicate-1 (TS-1) as a catalyst to epoxide propylene to PO. − However, the HPPO process suffers from low propylene conversion and hydrogen efficiency. − Meanwhile, epoxidation of propylene with N 2 O as an oxidant also attracts some attention but poor catalytic stability limits its further development. − …”

Reduction of O2 to H2O2 using Small Polycyclic Molecules

“…Worldwide production exceeds 5.5 million metric tons in 2015 and it continues to climb 3 . It is also used in several other applications including the synthesis of organic chemicals such as Propylene Oxide through the hydrogen peroxide propylene oxide (HPPO) process where hydrogen peroxide is used as the oxidant 9,10 . HPPO is the integration of two processes: first the anthraquinone (AQ) process synthesizes hydrogen peroxide and is then integrated with the propene epoxidation process catalyzed by titanium silicalite 11 .…”