摘要
对不同碱金属含量和不同温度水汽处理的丝光沸石样品，用ＸＲＤ和ＩＲ进行了物性表征，对其中某些样品以甲醇与氟合成甲胺反应用连续反应一在线分析进行了考察．水汽处理后，沸石发生骨架脱铝并保持很高的结晶度，其Ｂ酸总酸量及强酸量均剧降；甲醇转化活性反而提高，二甲胺选择性也显著提高，三甲胺选择性降至很低．表明过多、过强的酸性中心于本反应无益．此外，沸石经水汽处理后发生多种变化，产生了良好的择形催化效应．
he samples containing different alkali metal amounts and treatedhydrothermally at different temperatures are characterized. After thetreatment, some framework Al is dealuminated and the high crystallinity still remains; the band at 3612 cm-1, assigned to OH in Al(OH)Si,greatly decreases in its intensity, while a new nonsymmetric band at3660 cm-1 appears and covers the remaining 3612 cm-1 band. The 3660cm-1 band is probably assigned to the defect hydroxyl group, which isnonacidic in nature under our experimental conditions. The reactivityfor methylamine synthesis via methanol and ammonia on some samplesis also observed. Compared with the untreated samples, the hydrothermally treated ones are enhanced in catalytic activities, i. e. they havehigher conversion of methanol, higher selectivity for DMA and suppressed selectivity for TMA. It is indicated that the high activity andhigh selectivity for DMA of the mordenite modified with alkali metaland treated hydrothermally are attributed to the existence of certainBronsted acid sites with moderate strength.
基金
国家自然科学基金
关键词
丝光沸石
甲胺
合成反应
表征
ordenite, acidity, methylamine synthesis, shapeselectivity
