Catalysts For The Oxidative Methylation Of Toluene To Styrene

The process for the production of styrene directly from other available sources, such as toluene and methane, would potentially reduce the cost, and provide a new route for an alternative petroleum feedstock. Oxidative methylation of toluene with methane to styrene and ethylbenzene is one of the promising attempts to satisfy this need. The bialkal -metal-compounds-promoted bialkaline earth metal oxides M₁A+M₂A/MgO-M₃O (where M₁,M₂=Li,Na,K; M₃=Ca,Sr,Ba; A=SO₄^2-, NO₃^-,Cl^-,OH^-) were prepared by conventional coprecipitation and impregnation method. The oxidative methylation oftoluene with methane to styrene and ethylbenzene over aforementioned catalysts has been investigated systematically in this paper.The performances of the catalysts were investigated in a fixed- bed steady- state flow microreactor under atmospheric pressure. The experiments were carried out at 750℃, at a space velocity of 14000ml/g.h, at a C₇H₈:CH₄: O₂:N₂ partial pressure ratio of 1:11.2:2.1:10.4. It was found that Na⁺-K⁺/MgO-CaO (5:5:45:45mol%) was the most effective catalyst when alkali precursors were M₂SO₄(where M=Li,Na,K). The highest conversion of toluene(49.3%), the highest C₈-selectivity(47.3%) and the highest C₈-yield(23.3 SO were obtained over Na⁺-K⁺/MgO-CaO (5:5: 45: 45mol%) catalyst under aforementioned condition. The total C₈ -selectivity and C₈-yield remained almost unchanged for a period of 60h. After the reaction, coke deposits were not observed on the catalyst.