钛硅分子筛催化剂的研究进展

1、Research progress of titanium silicalite catalysZhan gxiao mingZha ngzhaor ongSoujiqua nLishube n(La nzhou In stitute of Chemical Physics fine petrochemical in termediates Natio nal Engin eeri ng Research Cen ter, Lan zhou 730000)The role of titanium catalyst in the oxidation reaction of organic com

2、pounds is well known 1,2. Introduced in the molecular sieve framework due to the molecular sieve hav ing a regular pore structure and large specific surface area characteristics, hetero atom, hav ing an oxidati on-reduct ion ability to prepare no vel catalytic oxidati on catalyst, has bee n more in

3、teresti ng subject in 1983 ENI 3 the T ar amasso its collaborators first successful syn thesis of the titanium-ccontaining zeolite catalyst of TS-1, a subsequent study found, Tam mon ia oxidati on 7 S-1 with H2O2 aqueous soluti on as oxida nt and the oxidatio n reacti on of a series of orga nic comp

4、o un ds, such as olefi n epoxidatio n 4, the aromatic hydrocarb on ring hydroxylati on 5, 6, ket one, alka ne oxidation8, 9 and the alcohol oxidation 10 and so the process has a unique shape-selective catalytic function as compared with other types of catalytic systems, the system (1) the mild react

5、i on con diti ons (atmospheric pressure, 0 - 100 °C); (2) the unique fun cti on of the shape-selective catalytic oxidati on; (3) en vir onmen tal frie ndli ness.TS-1 has been very limited because the aperture is only about 0. 55 nm, and its range of applications where the aerodynamic diameter i

6、s greater than 0. 60 nm substrate molecules can not enter within its pores without reactivity. Orderovercome this limitati on, the type of catalyst to get a wider range of applications, the majority of scientists have successfully synthesized T S-2 11, Ti-Beta 12 and a series of large aperture zeoli

7、te catalysts.In recent years, with the development of the petroleum refining and fine petrochemical tech no logy requires the use of some reorga ni zati on of the oil to be effective. M41S 13, 14, HMS 15 a nd MSU 16 series of mesoporous molecular sieves Tiheteroatom derivatives T i-MCM-41 17, Ti-MCM

8、-48 18, Ti-HMS 19, 20 a nd of Ti-the MSU 16 emerged, the latter in the selective oxidatio n of orga nic compo un dsshowed higher catalytic activity.This paper reviews the recent years, the progress made in terms of microporous and mesoporous tita nium silicalite catalyst preparati on, characterizati

9、 on, and catalytic react ion.T S-1 is first syn thesized, and also so far bee n studied most, and more thoroughly of a class of titanium silicalite catalyst. T S-1 is a Silicalite-1 isomorphously substituted derivatives thereof, having the MFI structure. TS- work and the results achieved many commen

10、ts have been reported 10, 21 - 24 here only a brief overview of the TS-1 preparatio n, characterizati on, and their corresp onding catalytic react ion.The classical method of preparing a zeolite catalyst is a hydrothermal syn thesis method in the the earliest pate nt literature, Tar amasso 3 reporte

11、d two preparation T S-1 The method of one is tetraethyl orthosilicate (T EOS) and tetraethylammonium n-titanate (TEOT) as silica source and a titanium source, and tetrapropyl ammon ium hydroxide (TPA OH) as templati ng age nt;other is a silica sol as a silic on source, and to dissolve in H2O2 the ti

12、ta nate as tita nium source TPAOH templat ing age nt in additi on to the hydrothermal syn thesis method, the TS -1 can also be obta ined by the method of sec on dary syn thesis TiCI4 and dealu min atio n of ZSM-5 for vapor phase react ion, to give with hydrothermal synthesis method is similar to the

13、 structure 25, but this method is easy to cause anatase. Huanxin et al 26 for the titanium source, TEOS as a silic on source, and succeeded in syn thesiz ing a T S-1 to T iCI3 The same catalytic activity, with the same reported in the literature, and the process can be effectively preve nted from ge

14、n erati on of an atase In additi on, Tuel and T aarit, continuous coverage positive ions with phosphorus 27, 1,6 - hexamethylenediammoniumion (Di -TPA) 28, tetraethyl ammoniumhydroxide (TEAOH) / T PAOH and T EAOH / tetrabutyl ammo nium hydroxide (T BA OH) 29 as a template to prepare T S-1 process. d

15、escribed using different Preparation of Template T S-1 is likely the. Preparation of Titanium Silicalite reage nt over Na +, K + and other alkali metal ions of the concentration should be sufficiently low, because the alkali metal ions will hin der the tita nium atom in the molecular sieve framework

16、 embedded; ano ther the one hand, to prevent the preparation process difficult to dissolve the anatase anatase formation will lead to subsequent reaction of H2O2 decomposition and reduce the catalytic activity in order to prevent the gen erati on of an atase, the preparati on process should be vigor

17、ously stirred, so that tita nium source in the silic on source is highly fragme nted., Than garaj, 7 the slower rate of hydrolysis the of tetrabutylammoniumpositive titanate(TBOT) Alternate TEOT, with an hydrous isopropyl alcohol as a co-solve nt, and achieved good effect.TS-1 zeolite catalyst uniqu

18、e shape-selective catalytic oxidati on fun ctio n, un doubtedly has a direct relati on ship with the skelet on of T i (IV) Therefore,the focus of such zeolite characterization is to determine the existence of T i (V) in the molecular sieveits ligand environment. characterization of TS-1, except for

19、rout ine characterizati on of X-ray diffractio n (XRD), N2 adsorpti on / desorptio n method, Fourier tran sform in frared spectroscopy (FT-IR) 29Si magic an glesp inning nu clear magn etic res onance spectroscopy (29Si-MAS-NMR), diffuse reflecta nce UV - visible spectrum (DR UVVis), X-ray photoelect

20、r on spectroscopy (XPS), exte nded X-ray absorpti on fine structure (EXAFS) and X-ray absorpti on n ear edge structure an alysis (XANES) and other tech no logies exist in the form of tetrahedral coord in atio n T i (V) providedthe basis forAccord ing to the naming of IUPAC 40, the aperture betwee n

21、2 - 50 nm molecular sieves for mesoporous molecular sieves. 1990s, class zeolite inorganic materials separation, ion exchange and catalytic disciplines one of the hot to Ion gcha in surfacta nts as templati ng age nt, have bee n successfully syn thesized M41S 13, 14, HMS 15 a nd MSU 16 a nd a series

22、 of mesoporous molecular sieves. formatio n mecha nism of the pore structure of mesoporous molecular sieve research has bee n reported41 - 46 At the sametime, Ti 17 - 20, V 47, Zr 48, Mn 49 a nd Cr 50 with the redox ability of tran siti on metal atoms into mesoporous molecular sieveskelet on structu

23、re, get a lot of new catalysts for the preparation of fine chemicals which T i atom isomorphous substitution in the hole titanium silicalite has important sig nifica nee of theoretical research and in dustrial applicati on value.The Gont ier and T uel 20 also Press T anev to method prepared T i-HMS,

24、 and preparati on process of various factors such as the proporti on of T iO2 / SiO2, isopropa nol, surface active age nt cha in len gth, characteristic of the titanium source and of Surf / SiO2 system. found that in the preparation process, whe n the two reage nts is mixed for 15 min, the result in

25、g product had with Hex ago nal various characteristics of most of Surf / SiO2 the best ratio of 0.3 in crease this proporti on of the aperture in creases, but the specific surface area and adsorptio n capacity is greatly reduced.Reviewed above on the syn thesis, characterizati on and catalytic oxida

26、tio n properties of tita nium silicalite and mesoporous molecular sieves prepared its heteroatom derivatives can be seen, the titanium silicalite as a new type of selective oxidati on catalyst dema ndis very importa nt to the increasing volume of the preparation of fine chemicals. especially in rece

27、nt years, the success of a series of mesoporous molecular sieves syn thesis and application, making the range of applications greatly broaden the field has attracted more and more atte nti on of researchersbut we should also see that there are still many problems in the field, such as the titanium s

28、ilicalite catalytic reacti on mecha ni sm, the formatio n mecha nism of mesoporous molecular sieves and skeleton in the presence of T i (IV) way for further exploration ofthese issuesa nd research will become a research focus in the coming period.钛硅分子筛催化剂的研究进展张小明 张兆荣 索继栓 李树本( 中国科学院兰州化学物理研究所精细石油化工中间体

29、国家工程研究中心 兰州 730000) 含钛催化剂在有机化合物氧化反应中的作用是众所周知的 1, 2 . 由于分 子筛具有规整的孔道结构和较大的比表面积等特点 , 在分子筛骨架中引入具有 氧化还原能力的杂原子 , 以制备新型的催化氧化催化剂 , 一直是人们比较感兴 趣的课题.1983年ENI 3的T ar amasso及其合作者首次成功地合成了含钛 的分子筛催化剂TS-1.随后的研究发现，T S-1在以H2O2水溶液为氧化剂的一系列有机化合物的氧化反应 , 如烯烃的环氧化 4 、芳烃环的羟基化 5, 6、酮的氨氧化 7 、烷烃的氧化 8, 9 及醇的氧化 10 等过程中有独特的择 形催化功能.

30、 同其他类型的催化体系相比较 ,该体系有( 1) 反应条件温和 ( 常压, 0-100 C );( 2)独特的择形催化氧化功能;(3)环境友好等优点。TS-1 由于孔径只有 0. 55 nm 左右, 而使其应用范围受到了很大的限制 . 凡 动力学直径大于 0. 60 nm 的底物分子因不能进入其孔道内部而无反应活性 . 为 了克服这一局限性 , 使该类催化剂能得到更为广泛的应用 , 广大科研工作者相 继成功地合成了 T S-2 11 、Ti-Beta 12 等一系列孔径较大的分子筛催化剂 。 近年来 , 随着石油炼制及精细石油化工技术的发展 , 要求对一些重组分油 加以有效利用 M41S 13

31、, 14、HMS 15及MSU 16等系列中孔分子筛及其Ti 杂原子衍生物 T i-MCM-41 17、Ti-MCM-48 18、Ti-HMS 19, 20 和Ti-MSU 16 等应运而生 , 后者在有机化合物选择氧化中表现出较高的催化活 性。本文综述了近几年在微孔及中孔钛硅分子筛催化剂的制备、 表征及催化反应 等方面所取得的进展 。T S-1 是最早合成的、也是迄今为止人们研究得最多且比较彻底的一类钛硅 分子筛催化剂 T S-1 是Silicalite-1的同晶取代衍生物，具有MFI的结构.关于TS-1的工作和所取得的成果已经有许多评述见诸报道 10, 21- 24. 这 里仅就TS-1的

32、制备、表征及其相应的催化反应等方面作一简要的概述。制备分子筛催化剂的经典方法是水热合成法 . 在最早的专利文献中 , Tar amasso 等 3 报道了两种制备 T S-1 的方法. 一种是以四乙基正硅酸酯 ( T EOS) 和四乙基正钛酸酯 ( TEOT ) 为硅源和钛源, 以四丙基氢氧化铵 ( TPA OH) 为模 板剂；另一种是以硅溶胶为硅源,以溶解于H2O2中的钛酸酯为钛源,用TPAOH 做模板剂 .除了水热合成法之外 , TS -1 也可以通过二次合成的方法得到 . 以 TiCI4和脱铝的ZSM-5进行气相反应，得到了与水热合成法类似的结构25. 但这种方法易于导致产生锐钛矿高焕新

33、等人26以T iCI3为钛源,TEOS为 硅源, 成功地合成了 T S-1, 具有同文献报道同样的催化活性 , 并且该过程可以 有效地防止锐钛矿的产生另外,Tuel和T aarit 连续报道了用磷正离子 27 、1, 6-己二铵离子 ( Di-TPA) 28 、四乙基氢氧化铵 ( TEAOH)/ T PAOH 及T EAOH/四丁基氢氧化铵(T BA OH) 29为模板剂制备T S-1的过程.说明用不同的模板剂制备T S-1是可能的.在钛硅分子筛的制备中,试剂中Na+、 K+ 等碱金属离子的浓度应足够低 , 因为碱金属离子会阻碍钛原子在分子筛骨架 中的嵌入； 另一方面, 要防止制备过程中产生难溶解的锐钛矿 .锐钛矿的形成会 导致后续反应中H2O2的分解而降低催化活性.为了防止锐钛矿的产生，制备过 程中应该激烈搅拌 , 使钛源在硅源中高度分散 . 另外, Thangaraj 等 7 以水 解速度较慢的四丁基正钛酸酯(TBOT )替代TEOT ,用无水异丙醇作为共溶剂， 取得了较好的效果 。TS-1分子筛催化剂独特的择形催化氧化功能,无疑与骨架中的T i