改性HZSM-5分子筛催化正戊烷与甲醇共芳构化反应

Co-aromatization of n-pentane and methanol catalyzed by modified HZSM-5 zeolite

采用浸渍法对HZSM-5分子筛进行改性,得到不同金属离子改性的分子筛,并且借助X射线衍射法和吡啶吸附红外光谱法对催化剂性质进行了表征。在固定床微反装置中,以正戊烷与甲醇为共芳构化反应原料,评价了改性HZSM-5分子筛催化剂的反应性能。结果表明:由Zn,Ag,Ni离子改性的催化剂相对结晶度依次为89.30%,88.96%,91.32%;当金属离子负载质量分数为2%时,采用Zn离子改性HZSM-5分子筛(SiO_2/Al_2O_3,摩尔比,38)催化剂,在反应温度为475℃,原料烃质量空速为2.0 h^(-1)及常压条件下,甲醇和正戊烷转化率分别约为100%,92.76%;当甲醇/正戊烷(摩尔比)为1∶1时,正戊烷转化率降至87.89%;甲醇的加入可抑制干气生成;共芳构化反应中存在协同作用,提高了芳烃选择性。在正戊烷与甲醇共芳构化反应中,当金属离子负载质量分数为2%时,与Zn离子改性催化剂相比,Ni或Ag离子改性的正戊烷转化率提高了约10个百分点。

The HZSM-5 zeolite was modified by the impregnation method to obtain zeolite catalysts with the modifications of different metal ions,and the catalytic properties were characterized by X-ray diffraction and pyridine adsorption infrared spectroscopy.The reaction properties of modified HZSM-5 zeolite catalysts were evaluated with n-pentane and methanol as co-aromatization materials in a fixed-bed micro-reactor.The results showed that relative crystallinity of the catalysts modified by Zn, Ag and Ni ion was 89.30%, 88.96% and 91.32% respectively;when the mass fraction of loaded metal ion was 2%, the methanol and n-pentane conversion was about 100% and 92.76% separately with HZSM-5 zeolite catalyst modified by Zn ion(SiO2/Al2O3, mole ratio,38) under the conditions of reaction temperature 475 ℃, mass space velocity of raw material 2.0h^-1 and atmospheric pressure;when the methanol/n-pentane(mole ratio) was 1∶1, the n-pentane conversion decreased to 87.89%;the added methanol could inhibit the formation of dry gas;the synergistic effects in the aromatization reaction improved aromatics selectivity.In the co-aromatization of n-pentane and methanol, when the mass fraction of loaded metal ion was 2%, the conversion of n-pentane modified by Ni or Ag ion was about 10 percentage points higher than that of catalyst modified by Zn ion.