The decomposition of neopentane has been used as a probe reaction to test the acid strength of zeolites with different composition and framwork structures. For a series of dealuminated HM zeolites, the acid strength i...The decomposition of neopentane has been used as a probe reaction to test the acid strength of zeolites with different composition and framwork structures. For a series of dealuminated HM zeolites, the acid strength increases first and then decreases as the Si/Al ratio of the zeolites is increased. The strongest acid strength aPpears at Si/Al ratio 8.1. For zeolites with different framework structure, the acid strength is in the order of HM>Hβ >HSY>HZSM-5≈HZSM-12. Changes in acid strength are discussed in relation to structural properties of the zeolites.展开更多
以NH_4Y沸石为原料,采用(NH4)_2SiF_6去铝补硅得到了硅铝比在2.6—9.8范围内,结晶度高的富硅 Y 沸石。系统介绍了反应物浓度、反应温度和时间、(NH_4)_2SiF_6滴加速度、缓冲液浓度和用量等对产品性质的影响,并对造成这些影响的原因进行...以NH_4Y沸石为原料,采用(NH4)_2SiF_6去铝补硅得到了硅铝比在2.6—9.8范围内,结晶度高的富硅 Y 沸石。系统介绍了反应物浓度、反应温度和时间、(NH_4)_2SiF_6滴加速度、缓冲液浓度和用量等对产品性质的影响,并对造成这些影响的原因进行了探讨。用 XRD、SEM、DTA-TG-DTG 和 IR 等实验手段对不同硅铝比的富硅 Y 沸石进行了表征,发现随着硅铝比增加,Y 沸石的亲水性减弱,热稳定性提高,超笼和小笼羟基振动频率有规律地变化,质子酸强度增加。展开更多
MCM-22 zeolite with a high SiO2/Al2O3 ratio was synthesized in the hydrothermal system of Na2O-SiO2-Al2O3-（CH2）6NH and its catalytic performance in the C4-olefins cracking reaction was investigated. It was found tha...MCM-22 zeolite with a high SiO2/Al2O3 ratio was synthesized in the hydrothermal system of Na2O-SiO2-Al2O3-（CH2）6NH and its catalytic performance in the C4-olefins cracking reaction was investigated. It was found that MCM-22 showed an excellent catalytic performance on C4-olefins cracking reaction to produce propylene. The results indicated that high temperature and high LHSV（liquid hourly space velocity） were favorable for the production of propylene with a high selectivity. Lifetime test of HMCM-22 and HZSM-5 for the cracking of C4 olefins indicates that the deactivation rate of HMCM-22 is lower than that of HZSM-5.展开更多
文摘The decomposition of neopentane has been used as a probe reaction to test the acid strength of zeolites with different composition and framwork structures. For a series of dealuminated HM zeolites, the acid strength increases first and then decreases as the Si/Al ratio of the zeolites is increased. The strongest acid strength aPpears at Si/Al ratio 8.1. For zeolites with different framework structure, the acid strength is in the order of HM>Hβ >HSY>HZSM-5≈HZSM-12. Changes in acid strength are discussed in relation to structural properties of the zeolites.
文摘以NH_4Y沸石为原料,采用(NH4)_2SiF_6去铝补硅得到了硅铝比在2.6—9.8范围内,结晶度高的富硅 Y 沸石。系统介绍了反应物浓度、反应温度和时间、(NH_4)_2SiF_6滴加速度、缓冲液浓度和用量等对产品性质的影响,并对造成这些影响的原因进行了探讨。用 XRD、SEM、DTA-TG-DTG 和 IR 等实验手段对不同硅铝比的富硅 Y 沸石进行了表征,发现随着硅铝比增加,Y 沸石的亲水性减弱,热稳定性提高,超笼和小笼羟基振动频率有规律地变化,质子酸强度增加。
文摘MCM-22 zeolite with a high SiO2/Al2O3 ratio was synthesized in the hydrothermal system of Na2O-SiO2-Al2O3-（CH2）6NH and its catalytic performance in the C4-olefins cracking reaction was investigated. It was found that MCM-22 showed an excellent catalytic performance on C4-olefins cracking reaction to produce propylene. The results indicated that high temperature and high LHSV（liquid hourly space velocity） were favorable for the production of propylene with a high selectivity. Lifetime test of HMCM-22 and HZSM-5 for the cracking of C4 olefins indicates that the deactivation rate of HMCM-22 is lower than that of HZSM-5.
