SYNTHESIS AND CHARACTERIZATION OF HYDROXY-CRAL PILLARED CLAYS

被引:33
作者
ZHAO, DY [1 ]
YANG, YS [1 ]
GUO, XX [1 ]
机构
[1] CHINESE ACAD SCI,DALIAN INST CHEM PHYS,DALIAN 116023,PEOPLES R CHINA
来源
ZEOLITES | 1995年 / 15卷 / 01期
关键词
PILLARED CLAYS; THERMAL STABILITY; SYNTHESIS; CHARACTERIZATION; CHROMIUM;
D O I
10.1016/0144-2449(94)00016-L
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
This paper describes the preparation and characterization of new PILC materials with mixed pillars of Cr3+ and Al3+ intercalated between the layers of montmorillonite. Various Cr/Al ratios were studied to obtain the most suitable physicochemical products. The resulting materials showed basal spacing between 2.49 nm and 1.90 nm for air-dried samples and surface areas between 232 and 283 m(2)/g. The pillar structure, thermal stability, surface acidity, and reducing behavior of the pillared clay products were determined using Al-27 n.m.r., X-ray diffraction (XRD), d.t.a, diffuse reflectance spectroscopy (d.r.s.), e.p.r., i.r., NH3-t.p.d, t.p.r. The results suggest that Cr/Al ratios greatly affect the pillar structure, surface area, acidity, and thermal stability of hydroxy-CrAl pillared clay (CrAl-PILC), The pillar in CrAl-PILC with Cr/Al ratio <1 has a Keggin structure similar to that of hydroxy-Al pillared clay (Al-PILC), but the pillar structures of CrAl-PILC with Cr/Al ratio greater than or equal to 1 are large polyoxochromium complexes similar to those of hydroxy-Cr pillared clay. The surface acidity and thermal stability are increased by incorporating aluminum into a chromia pillar. There is relatively strong interaction between chromium and alumina in the pillars, which is enhanced with decreasing Cr/Al ratios. Reduction of the chromium(lll) was made difficult because of the interaction of chromium with alumina. Catalytic behavior responded to Cr/Al ratio, and incorporating Cr(lll) into an alumina pillar increased the kinetic stability and selectivity of the catalyst in the disproportionation of 1,2,4-trimethylbenzene compared with a PILC catalyst containing no chromium.
引用
收藏
页码:58 / 66
页数:9
相关论文
共 25 条
[1]  
AKITT JW, 1981, J CHEM SOC DA, V7, P1606
[2]  
CARRADO KA, 1986, INORG CHEM, V25, P4717
[3]  
EARLEY JE, 1965, TRANSITION METAL CHE, V1, P34
[4]   SYNTHESIS AND CHARACTERIZATION OF AL-GA PILLARED CLAYS WITH HIGH THERMAL AND HYDROTHERMAL STABILITY [J].
GONZALEZ, F ;
PESQUERA, C ;
BLANCO, C ;
BENITO, I ;
MENDIOROZ, S .
INORGANIC CHEMISTRY, 1992, 31 (05) :727-731
[5]   TEMPERATURE PROGRAMMED REDUCTION [J].
HURST, NW ;
GENTRY, SJ ;
JONES, A ;
MCNICOL, BD .
CATALYSIS REVIEWS-SCIENCE AND ENGINEERING, 1982, 24 (02) :233-309
[6]   DISPROPORTIONATION OF 1,2,4-TRIMETHYLBENZENE OVER MONTMORILLONITE PILLARED BY ALUMINUM-OXIDE [J].
KIKUCHI, E ;
MATSUDA, T ;
FUJIKI, H ;
MORITA, Y .
APPLIED CATALYSIS, 1984, 11 (2-3) :331-340
[7]  
KOSTAPAPAS A, 1988, J CHEM SOC CHEM COMM, P1403
[8]   CROSS-LINKED SMECTITES .1. SYNTHESIS AND PROPERTIES OF HYDROXY-ALUMINUM-MONTMORILLONITE [J].
LAHAV, N ;
SHANI, U ;
SHABTAI, J .
CLAYS AND CLAY MINERALS, 1978, 26 (02) :107-115
[9]   SORPTION AND CATALYSIS ON SODIUM-MONTMORILLONITE INTERLAYERED WITH ALUMINUM-OXIDE CLUSTERS [J].
OCCELLI, ML ;
INNES, RA ;
HWU, FSS ;
HIGHTOWER, JW .
APPLIED CATALYSIS, 1985, 14 (1-3) :69-82
[10]   NEW ROUTES TO THE PREPARATION OF PILLARED MONTMORILLONITE CATALYSTS [J].
OCCELLI, ML .
JOURNAL OF MOLECULAR CATALYSIS, 1986, 35 (03) :377-389