不同硅/铝比ZSM-35分子筛对戊烯骨架异构化性能的影响

Effect of n(SiO2)/n(Al2O3)Ratio on the Catalytic Performance of ZSM-35 Zeolites in Pentene Skeleton Isomerization

以市售ZSM-35分子筛为晶种,使用静态晶种法合成了具有不同投料硅/铝比(n(SiO2)/n(Al2O3))的ZSM-35分子筛,通过X射线衍射(XRD)、X射线荧光光谱(XRF)、扫描电镜(SEM)、氨气程序升温脱附(NH3-TPD)、氧气程序升温氧化(O2-TPO)等手段对其进行表征。以炼油醚化副产品C5馏分为原料,研究了不同硅/铝比ZSM-35分子筛催化剂的骨架异构化反应催化性能。结果表明,成功合成出了具有较高相对结晶度且为纳米薄片状堆积结构的ZSM-35分子筛。随着投料硅/铝比从30增加到200,ZSM-35分子筛XRF实测硅/铝比从19.59逐渐增加到60.01,其弱酸和强酸的酸强度都有一定程度的降低,相对酸量也随之降低;同时O2-TPO测定的反应后催化剂上碳燃烧的CO和CO2峰面积也逐渐降低,造成对反应性能的影响。随着投料硅/铝比的增大,ZSM-35分子筛催化正构戊烯异构化转化率和收率都呈现先增加后减少的趋势,其中当投料硅/铝比为100时,转化率和收率均达到最大值。

Using commercial ZSM-35 zeolites as crystal seed,a series of ZSM-35 zeolites with different n(SiO2)/n(Al2O3)were prepared successfully by static crystallization method.Various ZSM-35 zeolites were characterized by means of XRD,XRF,SEM,NH3-TPD and O2-TPO.Then the skeletal isomerization performance of the catalysts was studied by using the industrial C5 mixture as raw material,which is the by-product caused by etherification.NH3-TPD results indicate that the acid amount of ZSM-35 zeolites decreases with the increase of n(SiO2)/n(Al2O3),and the O2-TPO results show the higher n(SiO2)/n(Al2O3)favors less carbon residue.Results show that the conversion and yield of n-pentene isomerization of ZSM-35 zeolites increase and then decrease with the increase of n(SiO2)/n(Al2O3).When the n(SiO2)/n(Al2O3)is 100,the conversion and yield reach the maximum.