P/HZSM-5分子筛催化乙醇脱水制备乙烯

Catalytic dehydration of ethanol to ethylene over P/HZSM-5 zeolites

采用浸渍法制备一系列P/HZSM-5分子筛催化剂,考察P含量对乙醇脱水制备乙烯的影响,并以X线衍射(XRD)、N_2吸附脱附(BET)、^(27)AL核磁共振(^(27)AL MAS NMR)等表征手段研究了P物种对HZSM-5分子筛结构和酸性质的影响。结果表明:H_3PO_4的添加会在某种程度上促进骨架四面体Al原子的脱离,从而有效地降低催化剂酸强度,进而减弱了催化剂的活性,但有利于延长使用寿命。结合NH_3-TPD表征结果,P的添加量控制在2.0%比较合适。

A series of P/HZSM-5 zeolite catalysts were prepared by impregnation method and used in the dehydration of ethanol to ethylene.X-ray diffraction（XRD）,N_2 adsorption for specific surface area（BET）, temperature programmed desorption of ammonia（NH_3-TPD）,and Al nuclear magnetic resonance（^（27）Al MAS NMR） were used to obtain the information about structure and acid properties of HZSM-5 zeolites and the effect of P content on the catalytic performance.The results indicated that the addition of phosphoric acid promoted the dealumination from framework with some extent,reduced the acid strength of catalyst, and weakened the activity of the catalyst that was beneficial to the extension of its service life.Combined with the results of NH_3-TPD,it was concluded that P content of 2.0%was suitable.