MTP/MTO工艺技术成熟度？ development history and current commercial status of the lurgi methanol to propylene (mtp) process technology. in 1996, as part of its gas-based petrochemistry initiatives, lurgi started developing a proc-ess to convert methanol to propylene (mtp) based on a propriety catalyst exclusively supplied by süd-chemie. this zeolite based mtp catalyst was a result of several years of intensive co-development between süd-chemie and lurgi. lurgi’s mtp process begins with a vapor phase dehydration of methanol to dimethyl-ether (dme) process, in which vaporized methanol is cata-lytically converted over γ-alumina at temperatures between 250°c and 300°c to produce an equilibrium mixture of dme, methanol and steam. this mixture is then converted in a fixed-bed mtp reactor at 450-500°c (842-932°f) in the presence of steam, with more than 99% conversion of methanol and dme. the low coking tendency of the mtp catalyst makes it sufficient to provide for a simple, discontinuous catalyst regeneration process in the reactor itself. the raw propylene is obtained which can be purified to polymer grade propylene. different olefin-containing streams are separated and recycled to the reaction system, resulting in an overall carbon yield to propyl-ene of about 71%. by-products of lurgi’s mtp process are gasoline with a high octane number (ron ~98.7 / mon ~85.5), lpg and fuel gas. in 1999 and 2000, lurgi set up an initial single fixed-bed adiabatic reactor (0.3 kg/h methanol feed) pilot unit and subsequently a three-reactor (1.2 kg/h methanol feed per reactor) pilot unit at the frankfurt research and development center, where the catalyst performances were investi-gated and the process conditions were optimized for maximum propylene yield. lurgi claims its mtp unit design basis is derived from more than 9,000 hours of pilot plant operating data at its research and development center in germany. it’s been reported that the viability of the lurgi mtp process has been proved at a demonstration unit operated jointly with statoil at statoil's methanol plant in norway. in 2001 lurgi built a skid-mounted mtp demonstration unit (3 reactors, 360 kg/day methanol feed per reactor), and installed it at statoil’s tjeldbergodden, norway methanol complex to gain valuable insights of mtp process design and operation while demon-strating mtp technology’s capability of producing true polymer-grade propylene. in 2003, to confirm the quality of the propylene obtained in the mtp demonstration unit, samples were sent to borealis' innovation center in rønningen, norway, where it was polymerized with borealis' borstar process to polypropylene that met all specifications, and converted into thermoformed cups. after the demonstration unit was operated between november 2001 and april 2004. the re-sults helped lurgi to determine the service life of the catalysts under realistic conditions by continuously taking in the methanol feed from the final purification column of the statoil plant and testing influence of “real“ hydrocarbon recycles on product yield and catalyst activity. the results from the demonstration unit tests proved that the mtp catalyst life exceeds one year of operation. the results also showed that the zeolite-based catalyst could be easily regenerated more than a dozen times. in parallel, lurgi has been optimizing the mtp process flowsheet including sequence of component separation and heat integration studies for commercial process design packages. an important design distinction of the lurgi mtp process is the conversion of the methanol to propyl-ene in two sequential reaction steps. dme is produced as the primary intermediate in the first step, which is then converted to propylene in a separate reactor system in the second step. this appears to facilitate the use of fixed-bed reactors, performance of catalysts, and operational con-ditions that maximize propylene yields. a fluidized-bed reactor would probably otherwise be required for temperature control purposes of the exothermic methanol-to-propylene reaction if it were to be conducted in a single reaction vessel configuration. furthermore, a fluidized-bed reac-tor may limit the choice of catalysts to those with high attrition resistance but which may not be optimal for propylene production. although no commercial-scale plants yet exist, shenhua group’s $1.5-billion, coal-to-chemicals complex using lurgi’s mtp technology is currently under construction in china’s ningxia coal area. the facility will produce 540,000 mt/year of polypropylene from coal via the methanol-to-propylene (mtp) route. completion is scheduled for early 2009 [chemical week, nov. 1, 2006, p. 20]. reportedly, datang international power generation’s mtp project in china and fanavaran petrochemicals’ mtp project in iran have been experiencing delays [chem_2006].t [ ]查看更多
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