ZSM-11分子筛的碱处理及其正十二烷催化裂解性能

Alkali Treatment of ZSM-11 Zeolite and Performance for Catalytic Cracking of n-Dodecane

研究了碱处理对ZSM-11分子筛的微观结构、酸性质和催化裂解性能的影响。采用不同浓度的氢氧化钠对ZSM-11分子筛进行碱处理,得到了级孔ZSM-11分子筛。用XRD,SEM,TEM,NH3-TPD,N2低温吸附-脱附等手段对碱处理后的分子筛进行了表征。以正十二烷为模型燃料,在550℃、4 MPa的条件下评价了分子筛的催化裂解性能。结果表明,碱处理导致HZSM-11分子筛晶粒内形成介孔、比表面积和酸量增加。碱处理的ZSM-11分子筛表现出较高的催化裂解活性。其中,用浓度为0.1 mol/L的氢氧化钠溶液处理的HZSM-11分子筛,催化活性最高。与未处理的HZSM-11分子筛相比,正十二烷的平均转化率提高了约58%。

In this paper the effects of alkaline treatment on texture,acid properties and catalytic cracking performance of ZSM-11 zeolites have been studied. Hierarchical ZSM-11 zeolites were prepared by alkali treatment with the different concentration of Na OH solutions. The resulting zeolites were characterized by XRD,SEM,TEM,NH3-TPD,N2-adsorpotion / desorpotion and their catalytic performances were evaluated by using catalytic cracking of n-dodecane at 4 MPa and 550 ℃. It is found that alkali treatment on ZSM-11 induced the formation of mesopores in crystals,and increased in the specific surface area and the amount of acid,resulting in the improvement of the conversion of n-dodecane catalytic cracking. The HZSM-11 catalyst obtained by alkaline treatment with 1. 0 mol / L Na OH solution exhibited the highest catalytic activity with the enhancement of ca. 58% in the average conversion compared to the untreated HZSM-11 zeolite.