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首页> 外文期刊>RSC Advances >Influence of Mg/CTAB ratio on the structural, physicochemical properties and catalytic activity of amorphous mesoporous magnesium silicate catalysts
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Influence of Mg/CTAB ratio on the structural, physicochemical properties and catalytic activity of amorphous mesoporous magnesium silicate catalysts

机译：Mg / Ctab比率对无定形间镁硅酸镁催化剂结构，物理化学性质和催化活性的影响

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This study investigated the physicochemical and catalytic properties of mesoporous magnesium silicate catalysts prepared at various Mg/CTAB ratios (0.25, 0.50, 0.75 and 1.00). The XPS analysis detected a mixture of enstatite and magnesium carbonate species when the Mg/CTAB ratio was 0.25, and 0.50. A mixture of forsterite and magnesium carbonate species were detected when the Mg/CTAB ratio was 0.75 whereas for the Mg/CTAB ratio of 1.00, enstatite and magnesium metasilicate species were detected. A catalyst with the Mg/CTAB ratio of 1.00 demonstrated the highest catalytic activity in the oxidation of styrene. The styrene conversion rate was 59.0%, with 69.2% styrene oxide (StO) selectivity. The H _(2) O _(2) molecules were activated regio-specifically by the magnesium species to prevent rapid self-decomposition while promoting selective interaction with styrene. All the parameters that influence the styrene conversion and product selectivity were evaluated using analysis of variance (ANOVA) with Tukey's test. The ANOVA analysis showed that the reaction time (h), Mg/CTAB ratio, styrene/H _(2) O _(2) ratio, catalyst loading (mg) and temperature (°C) affect styrene conversion and product selectivity (StO) significantly ( p < 0.05). The oxidation of styrene was well fitted to the pseudo-first-order model. The activation energy, E _(a) of the catalysed styrene epoxidation reaction was calculated to be 27.7 kJmol ~(?1) . The catalyst can be reused several times without any significant loss in its activity and selectivity. The results from this study will be useful in designing and developing low cost, high activity catalysts from alkaline earth metals.
机译：本研究研究了在各种Mg / CTAB比例（0.25,0.50,0.75和1.00）的中孔镁硅酸镁催化剂的物理化学和催化性质。当Mg / Ctab比率为0.25和0.50时，XPS分析检测到山牙石和碳酸镁物质的混合物。当Mg / Ctab比率为0.75时，检测到碳酸盐和碳酸镁物质的混合物，而对于1.00，检测到1.00的Mg / Ctab比例，则检测到山胺酸盐和镁均硅酸盐物质。 Mg / Ctab比为1.00的催化剂在苯乙烯的氧化中显示出最高的催化活性。苯乙烯转化率为59.0％，氧化苯乙烯（STO）选择性为69.2％。 H _（2）o _（2）分子由镁物质的最小值激活，以防止快速自分解，同时促进与苯乙烯的选择性相互作用。使用具有Tukey测试的差异（ANOVA）分析评估影响苯乙烯转化和产品选择性的所有参数。 ANOVA分析表明，反应时间（H），Mg / Ctab比，苯乙烯/ H _（2）O _（2）比，催化剂负载（Mg）和温度（℃）影响苯乙烯转化和产品选择性（STO ）显着（P <0.05）。苯乙烯的氧化适合于伪一阶模型。将催化的苯乙烯环氧化反应的活化能量，E _（A）计算为27.7kJmol〜（？1）。催化剂可以重复使用几次，而不在其活性和选择性中的任何显着损失。该研究的结果将用于设计和开发来自碱土金属的低成本，高活性催化剂。

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