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首页> 外文期刊>Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications >Guaiacol hydroxyalkylation with aqueous formaldehyde:role of surface properties of H-mordenites on catalytic performance
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Guaiacol hydroxyalkylation with aqueous formaldehyde:role of surface properties of H-mordenites on catalytic performance

机译：甲醛基酚的愈创木酚羟烷基化：H-丝光沸石表面性质对催化性能的作用

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摘要

The hydroxymethylation of guaiacol to vanillic alcohols,which is an important step in the synthesis of vanillin from phenol,has been studied over commercial H-mordenites having three different Si/Al ratios,with the aim to establish relationships between catalytic performance and zeolite chemical-physical features.Catalysts have been characterized following adsorption and desorption of NH_3 and H_2O by means of both TPD and FT-IR spectroscopy,hence gathering information on the nature and abundance of acidic sites and the hydrophilic/hydrophobic behaviour of the solids.In the adopted range of Si/Al ratio,between 10 and 58,an increase in concentration of acid sites corresponds to a decrease in catalytic activity.The zeolite property mainly affecting catalytic performance is hydrophobicity,which controls the relative concentrations of reactants in the porous structure,finally affecting the conversion of guaiacol and the distribution of products.The sample having intermediate Si/Al ratio = 23 represents the best compromise between a high conversion of the aromatic,which is proportional to the Si/Al ratio,and a low selectivity to diarylcompounds,undesired by-products of the reaction.The latter are preferentially formed with respect to vanillols and to monoaryl by-products in more hydrophobic H-mordenites,having higher Si/Al ratio.
机译：已对具有三种不同Si / Al比的商品H-丝光沸石进行了研究，研究了愈创木酚羟基甲基化为香草醇的重要步骤，这是从苯酚合成香兰素的重要步骤，目的是建立催化性能与沸石化学结构之间的关系。通过TPD和FT-IR光谱对NH_3和H_2O的吸附和解吸进行表征，从而收集有关酸性位点的性质和丰度以及固体的亲水/疏水行为的信息。 Si / Al比值范围在10到58之间，酸位点浓度的增加对应于催化活性的降低。主要影响催化性能的沸石性质是疏水性，疏水性最终控制了多孔结构中反应物的相对浓度硅酸铝比为中等的样品= 23代表在芳族化合物的高转化率（其与Si / Al比成比例）与对二芳基化合物的低选择性，不期望的反应副产物之间的最佳折衷。后者相对于香草醛和单芳基优先形成副产物为疏水性更高的H-丝光沸石，具有较高的Si / Al比。

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