【摘要】 研究了磷和水蒸气联合改性HZSM 5样品的物化和催化性能。XRD和IR研究表明,没有新的晶相出现。NH3 TPD研究样品的酸性表明,经过磷改性后的样品的酸量明显下降。经过水热处理的样品的BET比表面明显降低,这可能归因于磷物种和铝物种对孔道的堵塞。氮吸附-脱附等温线研究表明,等温线为I型和IV型的复合型,滞后环为H4型。联合改性样品的正庚烷裂化转化率高于仅仅由水蒸气改性样品的正庚烷裂化转化率,从而显示出磷物种对沸石分子筛高温水蒸气脱铝的抑制作用。更多还原

【Abstract】 Physicochemical and catalytic properties of steam treated phosphorus-modified-HZSM-5 zeolites have been investigated. XRD and IR show that no new crystalline phase exists in the modified samples. Acidic properties of the samples have been characterized by ammonia temperature programmed desorption （NH₃-TPD）, indicating the introduction of phosphorus by impregnation of the zeolite with an aqueous solution of NH₄H₂PO₄ and steam treatment decrease the number of acid sites. After steam treatment, BET surface area decreases remarkably due to the blockage of channel by phosphorus species and dealuminated species. The nitrogen adsorption-desorption measurements suggest that the isothermal type of all samples is a combination of type I and type IV, all hysteresis loops resemble the H4-type in the IUPAC classification. The conversion of n-heptane over steam treated P-modified-HZSM-5 zeolite is higher than that of sole steam treated zeolites, showing a protective effect of the phosphorus against dealumination by hydrothermal treatment at elevated temperature.更多还原