FIELD: chemistry.
SUBSTANCE: invention relates to a method of selective conversion of oxygenate to propylene, involving the following steps: a) reacting oxygenate, which is in form of alcohols, ethers and carbonyl compounds or mixture thereof, and a diluent which is helium, argon, nitrogen, carbon monoxide, carbon dioxide, hydrogen, water, water vapour, C1-C5 paraffins, aromatic hydrocarbons or mixture of given materials in amount corresponding to 0.1:1-5:1 moles of diluent per mole of oxygenate, in the presence of bifunctional catalyst particles containing molecular sieves which can convert at least part of the oxygenate to C3 olefin and convert C2 and C4 + olefins to C3 olefins in a reaction zone which includes at least one moving-bed reactor, where the reaction zone functions under conditions selected for converting oxygenate to propylene, and catalyst circulation rate in the reaction zone selected to obtain catalyst work cycle time of 200 hours or less, obtaining a stream of outgoing product containing basic amount of C3 olefin product and water by-product and less amount of C2 olefin, C4 + olefins, C1-C4 + saturated hydrocarbons and trace amounts of unreacted oxygenate, by-products formed by oxygenates, and aromatic hydrocarbons; b) passing the stream of outgoing product into a zone for splitting, cooling and splitting the stream of outgoing product into a vapour fraction rich in C3 olefins, a water fraction containing unreacted oxygenate and by-products formed by oxygenates, and a liquid hydrocarbon fraction containing heavier olefins, heavier saturated hydrocarbons and trace amounts of aromatic hydrocarbons; c) recycling at least part of the water fraction extracted from step b) to step a) to provide at least part of diluent used there; d) splitting the water fraction into a fraction rich in C2 olefin, a fraction of product rich in C3 olefin, and a first fraction rich in C4 + olefins; e) recycling at least part of the fraction rich in C2 olefin, or the first fraction rich in C4 + olefins, or a mixture of given fractions to step a); and f) extraction of coke-containing particles of bi-functional catalyst from the reaction zone, oxidative regeneration of the extracted catalyst particles in a regeneration zone and returning the regenerated catalyst particles to the reaction zone.
EFFECT: use of given method reduces loss of selectivity and with respect to obtaining propylene during the work cycle in the method of converting oxygenate to propylene.
8 cl, 2 tbl, 1 dwg
