from first principles PP-I-1

PP-III-122The Mechanism of Methanol Conversion into С 2 -С 3 -Olefines on SAPOCatalystsBachurikhin A.L.N.D. Zelinsky Institute of Organic Chemistry RAS, Moscow, RussiaShao-kahn@yandex.ruС 2 -С 3 -olefines are large-scale products of chemical industry and can be used as initialsubstances for production of valuable chemical materials, such as polythene of low and highpressure, polypropylene, polyolefines, polystyrene, poly--olefines etc. At present,manufacture of С 2 -С 3 -olefine by traditional ways meets certain deficiency of raw materialsand high expenses of this processing because С 2 -С 3 -olefine market cost exceeds 1000 USDper ton. In this connection, the methanol to olefine (MTO) process seems to be very attractivefor future.In Zelinsky Institute of Organic Chemistry, the SAPO zeolite catalysts have been found to beeffective in methanol conversion into olefins С 2 -С 3 .The method of synthesis of SAPO-zeolite catalysts comprises using triethylamine as atemplate structure agent, which forms colloid under in the presence of sodium, ammonium orhydrogen fluoride and crystallizes at 180-205° for 20-60 h. The prepared SAPO-34 zeolitehas small size and high degree of crystallization.On the basis of analysis of experimental data, the model of the mechanism of MTOconversionis proposed.1) Excess of temperature of MTO-conversion is higher 450С is inexpedient in view ofactivization of the collateral processes overwhelming С 2 -С 3 -olefine formation2) Process appreciably proceeds on the radical - chain mechanism3) Methanol in dimethylether (DME) conversion is fast process, and further DME inprimary stable hydrocarbon radicals conversion (methylen and others) is the ratelimiting stage determining the general rate of process and character of distribution ofreaction products4) Increased DME-contents at intermediate stages blocks С 2 -С 3 -olefine formation5) Catalysts such as SAPO do not promote aromatization of С 2 -С 3 -olefine283