碱处理和Zn改性对HZSM-5催化LPG芳构化性能的影响  

Effect of alkali treatment and Zn modification on catalytic performance of HZSM-5 for LPG aromatization

作　　者：王翠[1,2] 张瑞珍[1,2] 邢普[1,2] 温少波[1,2] 赵玲玲[1] 郭端阳[1] 赵亮富[3] 

机构地区：[1]太原理工大学材料科学与工程学院,太原030024 [2]新材料界面科学与工程教育部重点实验室,太原030024 [3]中国科学院山西煤炭化学研究所,太原030001

出　　处：《天然气化工—C1化学与化工》2015年第6期13-17,共5页Natural Gas Chemical Industry

基　　金：中国科学院战略性先导科技专项课题(XDA07020200)

摘　　要：采用NaOH溶液对HZSM-5分子筛进行碱处理得到HZSM-5(AT),然后与拟薄水铝石混合、焙烧制得仿工业催化剂HZSM-5(AT)+γ-Al_2O_3,最后采用等体积浸渍法对HZSM-5(AT)+γ-Al_2O_3进行Zn改性得到Zn/(HZSM-5(AT)+γ-Al_2O_3),并采用XRD、N_2-吸附和NH_3-TPD等手段对改性催化剂的结构和酸性进行表征,考察其在液化气芳构化反应中的催化性能。结果表明:HZSM-5分子筛经碱改性,形成了少量介孔,但晶体结构基本不发生变化;HZSM-5(AT)+γ-Al_2O_3与HZSM-5+γ-Al_2O_3相比,弱酸量减少,强酸量增加;进而经Zn改性后,随Zn含量的增加,Zn/(HZSM-5(AT)+γ-Al_2O_3)的弱酸量增加,强酸量减少,总酸量先增加后减少。碱处理提高了催化剂在芳构化反应中的稳定性和BTEX选择性,但活性提高不明显,这可能与碱处理产生少量介孔提高催化剂容炭能力和择形性有关;再经Zn改性后催化剂活性明显提高,其中w(Zn)%为1.57%的催化剂表现出最好的催化性能,这可能与适量Zn改性提高了催化剂的强弱酸协同芳构化性能有关。Modified HZSM-5 zeolite catalysts Zn/（HZSM-5（AT）＋γ-Al_2O_3） were prepared by treating the HZSM-5 zeolite with Na OH solution, then mixing it with γ-Al2O3 and calcining, and then impregnating the obtained HZSM-5＋γ-Al2O3 with different concentration of Zn（NO3）2solution by incipient wetness method. The prepared catalysts were characterized by XRD, N_2-adsorption and NH3-TPD, and their catalytic performances for LPG aromatization were investigated. Results showed that after alkali treatment, the mesopores were formed on the surface of HZSM-5, but the structure of HZSM-5 was not destroyed. Compared HZSM-5（AT）＋γ-Al2O3 with HZSM-5＋γ-Al_2O_3, the amount of strong acid increased while the amount of weak acid decreased. Alkali treatment could improve the life of catalysts due to the existence of small amount of mesoporous, and appropriate Zn modification could improve catalytic activity and selectivity of BTEX significantly, which may be the result of synergistic catalysis of strong acid with weak acid. The catalyst Zn/（HZSM-5（AT）＋γ-Al2O3） with a Zn content of 1.57% by mass exhibited the best catalytic performances.

关 键 词：HZSM-5 碱处理 多级孔 Zn改性 低碳烃芳构化 

分 类 号：O643.32[理学—物理化学] TQ426[理学—化学]