NATURE OF VANADIUM SPECIES IN SNO2-V2O5-BASED CATALYSTS - CHEMISTRY OF PREPARATION, CHARACTERIZATION, THERMAL-STABILITY AND REACTIVITY IN ETHANE OXIDATIVE DEHYDROGENATION OVER V-SN MIXED OXIDES

被引:42
作者
BORDONI, S
CASTELLANI, F
CAVANI, F
TRIFIRO, F
GAZZANO, M
机构
[1] UNIV BOLOGNA, DIPARTIMENTO CHIM IND & MAT, I-40136 BOLOGNA, ITALY
[2] CNR, I-40136 BOLOGNA, ITALY
来源
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS | 1994年 / 90卷 / 19期
关键词
D O I
10.1039/ft9949002981
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
Tin-vanadium mixed oxides have been prepared either from V4+-Sn4+ solutions by coprecipitation, or by the solid-state reaction between SnO(OH)(2) and V2O5, and characterized by means of chemical analysis, FTIR spectroscopy, EPR, X-ray diffraction and surface area measurements. Interaction between the hydroxy groups of the tin oxohydrate and the vanadium ions, reduction of V5+ ions to V4+ and stabilization inside the rutile structure led to the formation of a VxSn1-xO2 solid solution after calcination at 700 degrees C. A maximum amount of 10 atom% of vanadium entered the SnO2 lattice; at values of up to x = 0.02, V4+ was likely to be homogeneously dispersed, while higher amounts probably formed V4+ oxide clusters inside the rutile matrix. In addition, amorphous V5+ oxide was formed over the rutile surface, and at an overall vanadium content greater than 20-25 atom% crystalline V2O5 was also formed. In samples where x greater than or equal to 0.02-0.03, the solid solution was not stable at temperatures greater than 700 degrees C, and some of the V4+ was released from the structure forming segregated amorphous V5+ oxide, while for x < 0.02 the solution was stable. The V-Sn mixed oxides were tested as catalysts for ethane oxidative dehydrogenation. The catalysts initially exhibited an unstable behaviour due to a reduction of the V5+ oxide in the reaction environment. Tin oxide activity was enhanced by the addition of V4+; for x = 0.018, also the selectivity to ethene at temperatures higher than 480 degrees C was significantly greater. In contrast, selectivity to ethene at low temperatures was lower for x > 0.018.
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页码:2981 / 3000
页数:20
相关论文
共 81 条
[1]   STRUCTURAL STUDY OF GELS OF V2O5 - VIBRATIONAL-SPECTRA OF XEROGELS [J].
ABELLO, L ;
HUSSON, E ;
REPELIN, Y ;
LUCAZEAU, G .
JOURNAL OF SOLID STATE CHEMISTRY, 1985, 56 (03) :379-389
[2]  
ADAMS DM, 1981, INORGANIC SOLIDS
[3]   OXIDATION ACTIVITY AND ACID-BASE PROPERTIES OF SNO-2-BASED BINARY CATALYSTS .1. SNO-2-V-2-O-5 SYSTEM [J].
AI, M .
JOURNAL OF CATALYSIS, 1975, 40 (03) :318-326
[4]   OXIDATION ACTIVITY AND ACID-BASE PROPERTIES OF SNO-2-BASED BINARY CATALYSTS .2. SNO-2-MOO-3 AND SNO-2-P-2-O-5 SYSTEMS [J].
AI, M .
JOURNAL OF CATALYSIS, 1975, 40 (03) :327-333
[5]   STRUCTURAL DYNAMICS OF A V2O5-SNO2 CATALYST IN THE AMMOXIDATION OF 3-PICOLINE [J].
ANDERSSON, A .
JOURNAL OF CATALYSIS, 1981, 69 (02) :465-474
[6]  
ANDERSSON A, 1984, 8TH P INT C CAT WEIN, V5, P381
[7]  
ANDERSSON SLT, 1980, J CATAL, V64, P51
[8]   THE SELECTIVE DEHYDROGENATION OF ETHANE OVER SNO2-P2O5 CATALYSTS [J].
ARGENT, A ;
HARRISON, PG .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1986, (14) :1058-1058
[9]   RUTILE-TYPE COMPOUNDS .4. SIO2, GEO2 AND A COMPARISON WITH OTHER RUTILE-TYPE STRUCTURES [J].
BAUR, WH ;
KHAN, AA .
ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL CRYSTALLOGRAPHY AND CRYSTAL CHEMISTRY, 1971, B 27 (NOV15) :2133-&
[10]   AN ELECTRON-MICROSCOPY INVESTIGATION OF TIN MOLYBDENUM OXIDES [J].
BERRY, FJ ;
HALLETT, C ;
LORETTO, MH .
JOURNAL OF SOLID STATE CHEMISTRY, 1985, 58 (02) :176-180