July 1, 2013
C1 chemistry provides methanol for aromatics production. Inexpensive shale gas is leading to renewed interest in C1 chemistry. For example, methanol-to-olefins (MTO) technology is operating commercially in China. Although the methanol is made from coal-derived gas in the Chinese process, its success on a commercial scale has prompted consideration of this technology for making shale gas–based methanol in the United States. MTO technology was developed by Mobil in 1985 as part of its methanol-to-gasoline project in New Zealand.
A technology that has received much less attention is methanol-to-aromatics. Except for a small amount of coke oven–based benzene, almost all of the world’s aromatics (benzene, toluene, and xylenes [BTX]) are made from crude oil–derived naphtha. Aromatics are products of catalytic reformers that make gasoline in oil refineries or byproducts of naphtha-fed ethylene steam crackers in petrochemical complexes. Benzene is in short supply in the United States because the demand for gasoline is declining, and ethylene plant operators are choosing to crack inexpensive ethane instead of costly naphtha.
K. Karim and co-inventors investigated catalysts for converting methanol to aromatics. In perhaps the patent’s best example, the catalyst consisted of ZSM-5 zeolite impregnated with 2% lanthanum, 3% molybdenum, and 0.5% zinc. The dried catalyst was calcined by increasing the temperature at 1 °C/min to 450 °C and holding at this temperature for 6 h.
The 40–60 mesh size catalyst was loaded into a tubular reactor. MeOH was passed over the catalyst bed at a weight hourly space velocity of 9 h–1 at 450 °C and 1 atm pressure. MeOH conversion was 100%. Product yields were total aromatics, 18.8%; total BTX, 13.77%; and total xylenes, 7.98%. (Saudi Basic Industries [Riyadh]. US Patent 8,450,548, May 28, 2013; Jeffrey S. Plotkin)
[For another example of products made by C1 chemistry, see last week’s Patent Watch.—Ed.]
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