【摘要】 研究了磷、镁和磷镁改性HZSM-5沸石的酸性及其与二甲苯异构化,甲苯用乙烯烷基化和正己烷裂化反应的关系。结果表明,HZSM-5沸石的酸性,二甲苯异构化活性、甲苯乙基化活性、己烷裂化反应活性、环己烷吸附量和表面积均随HZSM-5沸石的磷、镁含量增加而下降。在3％磷改性的HZSM-5沸石中再添加镁,随镁含量增加,总酸量增加,二甲苯异构化酸量与活性却下降。二甲苯吸附和表面积也有同样的变化。而且随镁含量增加,甲苯烷基化反应中甲苯转化率上升,对位选择性提高;正己烷裂化反应酸性与活性也增加。上述三种反应的活性直接取决于改性HZHM-5沸石的酸性、酸类型以及孔结构。更多还原

【Abstract】 The acidity of phosphorus (P), magnesium (Mg) and P-Mg modified HZSM-5 zeolites and their activity for Xylene isomerization, toluene-ethylene alkylatipn and n-hexane cracking have been studied. It was found that the aci-dity, the activity for Xylene isomerization and n-hexane cracking and toluene conversion in the alkylation decreased with increasing the content of P and Mg in modified HZSM-5 zeolites. The adsorption amount of cyclohexane and the surface area of the modified HZSM-5 zeolites decreased with the increase of P and Mg content as well. On adding different amount of Mg to 3 % P modified HZSM-5 zeolite, as the Mg content increased, the total acid increased, but the acidity and the activity for Xylene isomerization decreased.Meanwhile the conversion of toluene and the selectivity for p-methylethylbenzene in toluene alkylation with ethylene,the acidity and activity for n-hexane cracking increased with the increase of Mg content. It is concluded that the activity for above three reactions was determined directly by the acidity, acid type and pore structure of the modified HZSM-5 zeolite catalysts.更多还原