Kinetic Studies and Reaction Network in the Epoxidation of Styrene Catalyzed by the Temperature-Controlled Phase-Transfer Catalyst [(C₁₈H₃₇)₂(CH₃)₂N]₇[PW₁₁O₃₉]

Abstract

The olefin epoxidation reaction is of great interest in recent years since epoxide is considered an important intermediate for a wide application range. H2O2-based catalytic epoxidation possesses the advantages of being cheap, green, and safe, which are quite advantageous in chemical technology. A phase-transfer catalyst, especially the phosphotungstate catalyst, has been applied in the epoxidation reaction with a high reaction rate and moderate reaction conditions. In this work, a phase-transfer catalyst, [(C18H37)2(CH3)2N]7[PW11O39], has been synthesized, and it showed high catalytic efficiency in styrene epoxidation. The influence of reaction time, temperature, oxidant concentration and amount, catalyst amount, and substrate concentration on the reaction performance was studied. A styrene conversion of 90.1% and selectivity of 90.6% could be achieved at 85 °C for 1 h with 3 equiv of H2O2 and 1.5 mol % catalyst. More importantly, kinetic models for the reaction network have been studied to optimize the reaction conditions and limit the side reactions.

Study on Reaction Mechanism and Process Safety for Epoxidation

“…Epoxidation of alkenes is a very important oxidation reaction, which aims to form an epoxide compound by adding one atom of oxygen between the carbon atoms at both ends of the double bond of alkenes . The Epoxide compound is one of the most valuable compounds in the pharmaceutical and spice industries. − In addition, it has an active ternary epoxy structure, which is prone to ring-opening reactions under various conditions, resulting in high-value-added chemical products and intermediates. , At present, the traditional epoxidation methods are mostly used in industry, the halogen alcohol method and peroxide acid method are mainly used to prepare epoxide compounds . The halogen alcohol method was widely used in the early industrial preparation of Epoxide, but its synthesis process was complicated, and the separation and treatment of byproducts were difficult and then caused serious environmental pollution.…”

“… 3 − 5 In addition, it has an active ternary epoxy structure, which is prone to ring-opening reactions under various conditions, resulting in high-value-added chemical products and intermediates. 6 , 7 At present, the traditional epoxidation methods are mostly used in industry, the halogen alcohol method and peroxide acid method are mainly used to prepare epoxide compounds. 8 The halogen alcohol method 9 was widely used in the early industrial preparation of Epoxide, but its synthesis process was complicated, and the separation and treatment of byproducts were difficult and then caused serious environmental pollution.…”