Process for producing c2-c4 olefins from methanol

Abstract

The invention relates to a process for preparing C2-C4 olefins from methanol, comprising the steps of: A) feeding a feed stream A comprising methanol into a dimethyl ether fixed bed reactor and catalytically converting methanol to dimethyl ether to obtain a product stream A1 comprising dimethyl ether, methanol and water vapor; B) mixing stream A1 with one or more hydrocarbon recycle streams R comprising C2-C6 hydrocarbons and catalytically converting it in an olefin fixed bed reactor to a crude product stream B comprising C2-C4 olefins, C5-C6 hydrocarbon and C6+ hydrocarbons; C) cooling crude product stream B to obtain a hydrocarbon crude product stream C; D) separating hydrocarbon crude product stream C into at least one ethylene-comprising stream, at least one propylene-comprising stream, at least one stream comprising butenes, at least one stream comprising C5-C6 hydrocarbons, and at least one by-product stream N comprising C6+ hydrocarbons; E) recycling a portion of the C2-C4 olefins selected from ethylene, propylene and butenes that are obtained in step D), and at least a portion of the C5-C6 hydrocarbons that are obtained in step D) as one or more hydrocarbon recycle streams R into step B); F) obtaining at least one ethylene-comprising product-of-value stream F1, at least one propylene-comprising product stream F2 and optionally one or more product-of-value streams F3 comprising butenes from the streams obtained in step D); G) feeding at least a portion of the propylene-comprising product stream F2 into an olefin metathesis reactor and converting propylene to a product stream G comprising ethylene and butenes, leaving a substream F4 of stream F2 as the product-of-value stream; H) separating an ethylene-comprising product-of-value stream H1 and a product-of-value stream H3 comprising butenes from the product stream G; I) optionally recycling at least a portion of the butenes present in product-of-value stream H3 into step B), leaving a substream H4 as product-of-value stream; K) discharging the at least one by-product stream N comprising C6+ hydrocarbons; wherein based on 100% by weight of the C2-C4 olefins present as products of value in streams F1, F3, F4, H1 and H3 or H4, 30% to 60% by weight of ethylene, 30% to 60% by weight of propylene and 0% to 30% by weight of butenes are present and are recovered as products of value, and, based on C2-C4 olefins present in the one or more recycle streams R and the product-of-value and by-product streams F1, F3, F4, H1, N and H3 or H4, 0% to 10% of the ethylene, 30% to 60% of the propylene and 40% to 80% of the butenes are recycled into step B), and, based on crude product stream B, 20% to 40% of the propylene is conducted into the olefin metathesis reactor, or, based on the C2-C4 olefins present in the one or more recycle streams R and the product-of-value and by-product streams F1, F3, F4, H1, N and H3 or H4, 5% to 30% of the ethylene, 0% to 10% of the propylene and 40% to 85% of the butenes are recycled into step B), and, based on crude product stream B, 50% to 70% of the propylene is conducted into the olefin metathesis reactor.

Dependencies are inferred from the claim text.