负载型TS-1沸石膜催化剂的制备、表征及其催化性能研究

doi:10.15541/jim20160460

摘要/Abstract

摘要：

利用水热合成法在α-Al₂O₃陶瓷管表面制备了连续完整的钛硅(TS-1)沸石膜, 并且利用该膜催化剂催化丙烯直接环氧化合成环氧丙烷(PO)。采用SEM、XRD、FT-IR和UV-Vis等表征手段及丙烯环氧化反应测试, 详细研究了合成液中Ti/Si比对TS-1沸石膜形貌、结构及催化性能的影响。结果表明, 合成液中Ti/Si比在0.01~0.04范围内, 所合成的TS-1沸石膜均具备典型MFI型拓扑结构。但当Ti/Si比>0.02时, 随着Ti/Si比升高, TS-1沸石膜表面沸石颗粒排列变得杂乱, 且TS-1沸石沉积量逐渐减少, 沸石晶间缺陷增多, 丙烯渗透速率增大。而且, 当Ti/Si比= 0.03、0.04时, 由于所合成的TS-1沸石膜中存在大量非骨架钛, 导致在丙烯环氧化反应中PO选择性和PO生成速率明显降低。当Ti/Si比为0.02时, 合成的TS-1沸石膜骨架钛含量最高, 其催化性能最佳, H₂O₂转化率、PO选择性和生成速率分别为12.43%、95.80%和15.78 mmol/(h·g)。TS-1沸石膜在丙烯环氧化反应中重复使用8次, 其催化性能保持相对稳定。

关键词: 钛硅沸石, 沸石膜, 水热合成, 环氧丙烷

Abstract:

Titanium silicalite-1(TS-1) zeolite membranes were successfully prepared on porous α-Al₂O₃ tubes using hydrothermal synthesis method for epoxidation of propylene to propylene oxide (PO). SEM, XRD, FT-IR, and UV-vis spectroscopy were used to investigate the effects of Ti/Si molar ratio on surface morphology and structure of the TS-1 zeolite membrane. When the Ti/Si molar ratio was set between 0.01 and 0.04, continuous and compact TS-1 zeolite membranes were deposited on the porous support. The obtained TS-1 membranes displayed typical characteristics diffraction peaks of MFI structure. With the increase of the Ti/Si molar ratio, the deposition amounts of the TS-1 zeolites decreased. As a result, some intercrystalline defects were formed and the propylene permeance increased. For the TS-1 membranes prepared with the Ti/Si molar ratio of 0.03-0.04, poor PO selectivity and low PO formation rate were observed in the epoxidation reaction of propylene. This was attributed to the formation of extra-framework TiO₂ in the TS-1 membranes that could catalyze the decomposition of hydrogen peroxide. In contrast, the TS-1 membrane prepared with the Ti/Si ratio of 0.02 exhibited the best catalytic performance. The conversion of hydrogen peroxide, PO selectivity and PO formation rate were 12.43%, 95.80% and 15.78 mmol/(h·g), respectively. Moreover, the regeneration tests revealed that the catalytic ability of the TS-1 membrane was relatively stable after regeneration for 8 times. And the TS-1 membrane was easier to be separated and recovered after reaction.

Key words: titanium silicalite-1 zeolite, zeolite membrane, hydrothermal synthesis, propylene oxide

中图分类号:

TQ174

郭宇, 李东昕, 吴红梅, 金玉家, 周立岱, 陈强强. 负载型TS-1沸石膜催化剂的制备、表征及其催化性能研究[J]. 无机材料学报, 2017, 32(6): 631-636.

GUO Yu, LI Dong-Xin, WU Hong-Mei, JIN Yu-Jia, ZHOU Li-Dai, CHEN Qiang-Qiang. Preparation, Characterization and Catalytic Performance of Supported Titanium Silicalite-1 Zeolite Membrane Catalyst[J]. Journal of Inorganic Materials, 2017, 32(6): 631-636.

图/表 9

表1 TS-1沸石膜的制备条件

Table 1 Preparation conditions of the TS-1 membranes

Sample	Ti/Si ratio	Time/h	Synthesis solution
Sample	Ti/Si ratio	Time/h	TEOS	TPAOH	TBOT	H₂O
T_0.01	0.01	48	1	0.36	0.01	250
T_0.02	0.02	48	1	0.36	0.02	250
T_0.03	0.03	48	1	0.36	0.03	250
T_0.04	0.04	48	1	0.36	0.04	250

图1 多孔氧化铝载体(a), 预涂晶种后的载体(b)及不同Ti/Si比((c)0.01, (d)0.02, (e)0.03, (f)0.04)合成的TS-1沸石膜的表面SEM照片

Fig. 1 SEM images of porous α-Al2O3 support (a), seeded support (b) and TS-1 membranes with different Ti/Si molar ratios ((c) 0.01, (d) 0.02, (e) 0.03, (f) 0.04)

图2 合成不同TS-1膜时釜底沸石分子筛的SEM照片

Fig. 2 SEM images of the TS-1 zeolites collected from bottom of autoclave(a) T0.01; (b) T0.02; (c) T0.03; (d) T0.04

图3 合成不同TS-1膜时釜底沸石分子筛颗粒尺寸

Fig. 3 Particle size of the TS-1 zeolites collected from bottom of autoclave

图4 不同TS-1沸石膜的沉积量和丙烯渗透速率

Fig. 4 Deposition amounts and C3H6 permeances of TS-1 membranes

图5 不同TS-1沸石膜的XRD(a)、FT-IR(b)和UV-Vis(c)图谱

Fig. 5 XRD patterns (a), FT-IR spectra (b) and UV-Vis spectra (c) of the resulting TS-1 membranes

图6 不同TS-1沸石膜在丙烯环氧化中所得到的H2O2转化率、PO收率和PO选择性(a)以及PO生成速率(b)

Fig. 6 Catalytic properties of the TS-1 zeolite membranes in terms of H2O2 conversion, PO yield, PO selectivity (a) and PO formation rate (b) in the epoxidation of propylene

图7 不同TS-1沸石膜在FT-IR谱图中I960/I800值

Fig. 7 Ratio of I960/I800 in the FT-IR spectra of the TS-1 membranes

图8 Ti/Si比为0.02时制备的TS-1沸石膜在丙烯环氧化反应中的再生性能

Fig. 8 Catalytic properties of the TS-1 membranes for repeated employment in epoxidation of propylene

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