甲醇定向转化制二甲苯的复合分子筛ZSM-5/EU-1的合成及其应用  

Synthesis of ZSM-5/EU-1 Composite Zeolite and Its Application in Conversion of Methanol to Xylene

作　　者：杨冬花[1] 王新波[1] 石宝宝[1] 武正簧[1] 李晓峰[2] 窦涛[2,3] 

机构地区：[1]太原理工大学化学化工学院,太原030024 [2]太原理工大学精细化工研究所,太原030024 [3]中国石油大学(北京)化工学院,CNPC催化重点实验室,北京102249

出　　处：《无机材料学报》2014年第4期357-363,共7页Journal of Inorganic Materials

基　　金：国家重点基础研究发展计划(973计划;2012CB215002);国家自然科学基金(20973123);山西省自然科学基金(2013011041-1);煤转化国家重点实验室(11-12-603)开放基金~~

摘　　要：以硅溶胶、硫酸铝、氢氧化钠、四丙基溴化铵以及硼酸和九水硝酸铁为原料，采用EU-1晶种，通过水热法合成了2种含杂原子的微孔结构ZSM-5／EU-1复合分子筛。采用XRD、SEM、N2吸附-脱附和NH3-TPD对合成样品进行了表征，并在连续流动固定床反应器上考察了该分子筛催化剂对甲醇N-甲苯反应的催化性能。结果表明-含杂原子微孔结构的ZSM-5／EU-1复合分子筛同时具有ZSM-5和EU-1的特征衍射峰，结晶度较好，平均孔径明显增大，当催化剂的酸强度和酸量增大时，有利于甲醇芳构化趋势以及二甲苯优先扩散。B-ZSM-5／EU-1催化产物中芳烃在油相中的选择性达到84-70％；B-ZSM-5／EU-1和Fe-ZSM-5／EU-1两种分子筛催化产物的芳香烃中二甲苯的含量最高，分别为41-32％～45-88％和33-88％～39-16％。由于B-ZSM-5／EU-1较高的酸性、酸量和相对较小的孔道内径（0-8060nm），较Fe-ZSM-5／EU-1更有利于产物中二甲苯的生成；不仅如此，B-ZSM-5／EU-1复合分子筛催化产物中对二甲苯在二甲苯中选择性范围为29-75％～47-47％；不过，Fe-ZSM-5／EU-1产物中对二甲苯在二甲苯中的含量最高可达53.75％，这是由于Fe-ZSM-5／EU-1复合分子筛的粒径较大，为催化反应提供了较长的孔道结构，易使产物中邻、间二甲苯在扩散过程中异构化转化为对二甲苯的缘故。Heteroatom-containing ZSM-5/EU-1 composite zeolites with porous structure were synthesized by hydrothermal method using silica sol, aluminum sulfate, sodium hydroxide, TPABr, boric acid and iron nitrate as raw materials, and EU-1 as crystal seed. The synthetic samples were investigated by XRD, SEM, N2 adsorption-desorption and NH3-TPD. Catalyst performance of the composite zeolites for conversion of methanol to xylene was evaluated on a continuous-flow reactor. The results show that the heteroatom-containing ZSM-5/EU-1 composite zeolite with good crystallinity has diffraction peaks for both ZSM-5 and EU-1. Its average pore size has been significantly enlarged and its amount and strength of acid were also increased, which benefited for the aromatization trend of methanol and the priority diffusion of xylene. Selectivity of aromatics in the oil phase can reach 84.70% when using B-ZSM-5/EU-1 as catalyst. It is found that the contents ofxylene product are the highest both in B-ZSM-5/EU-1 and in Fe-ZSM-5/EU-I catalytic products in the range of 41.32%-45.88% and 33.88%-39.16%, respectively. The reason why B-ZSM-5/EU-1 catalytic effect is better than that of Fe-ZSM-5/EU-1 is that the acidity of former is higher and pore diameter smaller （0.8060 nm）, both characters favoring xylene formation. However, the selectivity of p-xylene in B-ZSM-5/EU-1 cata- lytic xylene products is in the range of 29.75%-47.47% which is lower than that of Fe-ZSM-5/EU-1 with the highest of 53.75%. This result can be attributed to larger particle size of Fe-ZSM-5/EU-1 which provides a longer pore structure for the catalytic reaction so that o-xylene and m-xylene are easier to convert into p-xylene during the diffusion process.

关 键 词：晶种法 ZSM-5 EU-1复合分子筛 酸性 二甲苯 选择性 

分 类 号：O643[理学—物理化学] TQ426[理学—化学]