Methanol-to-light olefins

Barger, P.T., Wilson, S.T., and Holmgren, J.S. (1992) Metal alumino-phosphate catalyst for converting methanol to light olefins. US Patent 5,125,308. 

The 100 BPD MTG project was extended recently to demonstrate a related fluid bed process for selective conversion of methanol to light olefins (MTO). The products of the MTO reaction make an excellent feed to the commercially available Mobil Olefins to Gasoline and Distillate process (MOGD) which selectively converts olefins to premium transportation fuels ( 1). A schematic of the combined processes is shown in Figure 1. Total liquid fuels production is typically greater than 90 wt% of hydrocarbon in the feed. Distillate/gasoline product ratios from the plant can be adjusted over a wide range to meet seasonal demands. 

The goal of the MTO process is to convert methanol to light olefins, in particular ethylene, propylene and butenes. The key by-products of the reaction include the co-product water, C5+ hydrocarbons such as aromatics and heavier olefins, coke that remains on the catalyst at process conditions and light paraffins that are the primary sink for hydrogen lost during aromatic formation. Small amounts of H2 and COx are also typically observed in the MTO product, although these by-products could arise from feed and product decomposition on the reactor walls and internals at the temperatures that are typically used. 

Chen et al. (7,37,38,39,40) investigated the conversion of methanol to light olefins (MTO) using TEOM. The investigations included the influence of coke deposition on the selectivity, the effect of the crystal size of SAPO-34 on the selectivity and the deactivation of the catalyst for the MTO reaction, and modeling of the kinetics of the MTO reaction. Simultaneous measurements of coke deposition, conversion, and selectivities by TEOM combined with in situ GC analysis of the effluent gas... 

Utilization of methanol or DME for petrochemical applications has a much better chance of succeeding, as there is a much higher value added in going from methanol to light olefins. Even when the markets are soft, ethylene and propylene command prices of at least about 400 per tonne, and usually substantially more. Even on a pure fuel value basis, 400 per tonne for ethylene would be equivalent to about 8.00 per giga-Joule, or a very significant value-added markup. 

Distillate dewaxing Lube dewaxing Gas to aromatics Gas to Aromatics Light olefins to gasoline and distillate Methanol to gasoline Methanol to light olefins Xylene isomerization Toluene disproportionation Ethylbenzene synthesis 58-59) p-Xylene synthesis p-ethyltoluene synthesis... 

Spencer and Whittam ° used Fu-1 zeolite to convert methanol to light olefins. NaFu-1 and its H-form are considered to be small-pore zeolites, but they have a high external surface area because of their small crystallite size and plate morphology. Apparently, methanol conversion to hydrocarbons occurs mainly at the interior acid sites, while hydrocarbons can react on both types of acid sites. NaFu-1 showed negligible activity. Using a flow reactor at... 

The crystal size of the zeolites has been found to be an important factor influencing the conversion of methanol to light olefins. With the use of crystals of 1-2 p a higher selectivity for the production of C2 C olefins and particularly ethylene has been... 

SAPO-34, which has a narrow pore diameter, is highly selective for the conversion of methanol to C2-C4 olefins. Although the selectivity to aromatics on SAPO catalysts is lower than that on H-ZSM-5, the methanol conversion and the selectivity to C2-C4 olefins are 99 and 85 percent selectivity, respectively, on SAPO-34. Therefore, the yield of C2-C4 olefins is higher on SAPO-34 than on ZSM-5. SAPO-17 is active for the dehydration of methanol to light olefins." Anderson et al. also reported that SAPO-34 is highly selective for the formation of ethylene from methanol. ... 

Effects of Particle Size and Modified SAPO-34 on Conversion of Methanol to Light Olefins and Dimethyl Ether... 

In parallel to the Lurgj fixed bed MTP process, Tsinghua University proposed a fluidized bed MTP (FMTP) process based on the SAPO-18/34 zeo-hte catalyst. It was declared that this catalyst can limit the formation of the compounds of C4 and beyond, and thus prompt the yield of ethylene and propylene. FMTP process has two fluidized bed reactors. The first one is used to convert methanol to light olefins, and the second one is mainly for further converting ethylene and butylenes to propylene. In 2008, Tsinghua, together with its partners, built a FMTP demonstration unit (capacity of 30 kt/a of methanol feed) in Anhui, China. In September 2009, the demonstration unit was started up. The experimental data shows that the methanol conversion is almost 100%, and the propylene yield is close to 67.3% (CH2 basis). FMTP has not been industrialized so far. 

The UOP/HYDRO MTO process converts methanol to light olefins. The process provides greater selectivity to ethylene and propylene versus C4+ byproducts. 

Wilson S, Barger P. The characteristics of SAPO-34 which influence the conversion of methanol to light olefins. Microporous Mesoporous Mater 1999 29 117-26. 

Hajimirzaee, S., et al., 2015. Dehydration of methanol to light olefins upon zeoUte/alumina catalysts effect of reaction conditions, catalyst support and zeolite modification. Chemical Engineering Research and Design 93 (0), 541—553. 

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