硅烷对HZSM－5沸石分子筛的改性研究Ⅱ．硅烷化改性对HZSM－5表面酸性、吸附性能和催化性能的影响  

STUDY ON HZSM-5 ZEOLITES MODIFIED WITH SILANE SILANESⅡ.EFFECTON HEACIDITYADSIORPTION AND CATALYTIC PROPERTIES

作　　者：杨儒[1] 何瑞德[1] 雷依庆[1] 

机构地区：[1]中国科学院山西煤炭化学研究所,太原工业大学精细化工研究所

出　　处：《燃料化学学报》1995年第1期36-42,共7页Journal of Fuel Chemistry and Technology

摘　　要：以硅烷气体作为改性剂，对ＨＺＳＭ－５沸石进行了改性研究，并用ＮＨ＿３－ＴＰＤ，表面羟基和吡啶吸附态红外光谱的手段表征了改性样品。发现随着硅烷化程度的加深，强酸和弱酸开始降低，硅烷化程度ｗ％＞１．８３％后，酸性基本保持不变，这时改性只起到明显的缩孔作用。通过对改性沸石探针分子吸附行为的研究分析得知，硅烷化开始时，硅烷分子进入了孔道内，与内表面羟基反应，致使部分孔道堵塞，孔道变窄。硅烷化程度ｗ％＞１．８３％后，硅烷分子扩散进孔内受阻，转换到与外表面羟基反应，只起到改性外表面缩小孔径的作用。这种改性的ＨＺＳＭ－５沸石对甲醇胺化反应的活性和选择性都有很好的促进作用。Since the molecule size of silanes was smaller than the pore size of HZSM-5zeolites,the silanes molecule is able to get into its channel.Therefore,at the beginning ofsilanization,silanes reacted first with internal surface and then with external surface of zeo-lites,As a result,the total acid,stronger acid and weaker acid of modified zeolites all decrease during silanization and keep contant as silanization is over 1.83%. After this,modif-cation with silanes narrows only the pore size of zeolites.The IR spectra of adsorbed pyridine as molecule probe on the unmodified and modified zeolites showed that the Bronsted acidsite decreases after modification with silanes,but the Lewis acid site increases obviously withthe result that the amount of Lewis acid site exceeds that of Bronsted acid site,The resultverifies that the Bronsted acid and the Lewis acid site transform each other during silaniza-tion. The adsorption properties of HZSM-5 zeolites modified by silanes for several hydro-carbons have been studied.The adsorption amount of several hydrocarbons further indicatesthat there are different pore size and shape-selectivity in various modified HZSM-5. Theresult of methanol amination over modified HZSM-5 indicates clearly that the catalytic ac-tivity is related only to the acid strength instaed of the amount of acid site。 Thus the selectiv-ity of monomethylamine depends on the structure of modified HZSM-5.

关 键 词：酸性 吸附性能 沸石 催化性能 硅烷 

分 类 号：TQ424.25[化学工程] O627.41[理学—有机化学]