Si改性对HZSM-5催化剂MTO性能的影响
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摘要
以正硅酸乙酯(TEOS)为调控剂,调节HZSM-5(SiO_2/Al_2O_3=50)的孔结构与酸性,采用XRD、BET、NH_3-TPD等表征调节前后HZSM-5催化剂的晶相、孔结构和酸性,考察了Si沉积改性对HZSM-5催化剂MTO催化活性的影响。结果表明,采用TEOS进行Si改性的方法不会改变HZSM-5的骨架结构,焙烧后SiO_2覆盖在HZSM-5的表面,调变了HZSM-5的孔径、钝化了HZSM-5的酸性,提高了其对MTO反应的催化活性。当TEOS与HZSM-5质量比为0.15时,可以达到较好的改性效果,在保持甲醇转化率为100%的前提下,低碳烯烃选择性达到了65.40%,较改性前提高了18个百分点,丙烯的选择性30.97%,提升率为58%。
Regulation the pore structure and acidity on HZSM-5(SiO_2/Al_2O_3=50) by TEOS,characterized by means of XRD,BET,NH_3-TPD,and investigated the catalytic performance on MTO for the HZSM-5 before and after modified by different coverage of silica(the amount of TEOS).Results showed that the framework structure of HZSM-5 was unchanged after modified by TEOS.SiO_2 covering on the surface of HZSM-5 played a role in adjusting the acidity and reducing the orifice of HZSM-5 and its MTO catalytic activity was obviously improved.The appropriate loading of silica was 0.15(mTEOS/mHZSM-5),the modified HZSM-5 showed the better catalytic result,that the conversion of methanol was 100%,the selectivity of light olefins was 65.40%,it was 18 percentage point higher than the before modification,the propylene selectivity was 30.97% and the promotion rate was 58%.
Regulation the pore structure and acidity on HZSM-5(SiO_2/Al_2O_3=50) by TEOS,characterized by means of XRD,BET,NH_3-TPD,and investigated the catalytic performance on MTO for the HZSM-5 before and after modified by different coverage of silica(the amount of TEOS).Results showed that the framework structure of HZSM-5 was unchanged after modified by TEOS.SiO_2 covering on the surface of HZSM-5 played a role in adjusting the acidity and reducing the orifice of HZSM-5 and its MTO catalytic activity was obviously improved.The appropriate loading of silica was 0.15(mTEOS/mHZSM-5),the modified HZSM-5 showed the better catalytic result,that the conversion of methanol was 100%,the selectivity of light olefins was 65.40%,it was 18 percentage point higher than the before modification,the propylene selectivity was 30.97% and the promotion rate was 58%.
引文
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[2] 吴德,何琨.MTO与MTP工艺技术和工业应用的进展[J].石油化工,2015,44(1):1-10.
[3] 史建公,刘志坚,张敏宏,等.MTO催化剂中国专利技术进展(一)——ZSM-5系列分子筛[J].中外能源,2013,18(8):70-75.
[4] 史建公,刘志坚,张敏宏,等.MTO催化剂中国专利技术进展(二)——SAPO系列分子筛[J].中外能源,2013,18(9):63-72.
[5] Tian P,Wei Y X,Ye M,et al.Methanol to olefins (MTO):From fundamentals to commercialization[J].ACS Catalysis,2015,5(3):1922-1938.
[6] Khanmohammadi M,Amani Sh,Garmarudi A B,et al.Methanol-to-propylene process:Perspective of the most important catalysts and their behavior[J].Chinese Journal of Catalysis,2016,37(3):325-339.
[7] 潘红艳,田敏,何志艳,等.甲醇制烯烃用ZSM-5 分子筛的研究进展[J].化工进展,2014,33(10):2625-2633.
[8] 王林,王政,安良成,等.磷改性ZSM-5/磷酸铝复合分子筛在甲醇制丙烯反应中的应用[J].石油学报:石油加工,2013,29(4):597-604.
[9] 杨依苏.改性ZSM-5沸石催化剂的制备及其甲醇制丙烯(MTP)反应[D].上海:复旦大学,2012.
[10] Schulz H.“Coking” of zeolites during methanol conversion:Basic reactions of the MTO-,MTP- and MTG processes[J].Catalysis Today,2010,154(3/4):183-194.
[11] 李文慧.ZSM-5分子筛催化剂上积炭物种的研究[D].大连:大连理工大学,2014.
[12] 严丽霞.甲醇制丙烯催化剂的结构调控与性能研究[D].杭州:浙江大学,2015.
[13] 徐青,乐英红,高滋.化学液相沉积与沸石择形催化性能[J].催化学报,1998,19(4):349-353.
[14] 邹薇,杨德琴,孔德金,等.硅改性HZSM-5沸石上甲苯与甲醇选择性甲基化的研究[J].化学反应工程与工艺,2006,22(4):305-309.
[15] 王凯,童锴,胡超,等.液相硅沉积改性HZSM-5分子筛的择形吸附分离性能研究[J].功能材料,2015,46(14):14144-14148.