Methanol based options
MTO and MTP technologies are not yet commercial, but are on
the verge of becoming so. There is increasing interest in these technologies,
especially in China, which is looking to leverage its coal reserves for
chemicals production through methanol. The world's first MTO plant looks likely
to be at Shenhua (China), with a 2011 start-up targeted. The project will
include a 1.8-mtpa coal-based methanol plant, using Davy Process Technology and
a 600,000-tpa MTO plant, using Chinese technology. There have been some moves
to set up plants in Nigeria and Iran, using gas as a raw material for methanol,
but both projects are currently stalled.
Similarly, Lurgi is known to have a pilot MTP plant in
operation in Norway. Whilst a 400,000-tpa Iranian MTP project now appears to
have stalled, two MTP plants utilizing Lurgi technology to produce PP are under
construction in China and due to start up in 2009 and 2010.
The Chinese coal-to-olefins (CTO) cases show a decided
advantage at large scales, as compared to conventional steam cracking, and
justify the recent burst of activity in these projects. Two factors drive the
cost advantage: low coal costs and relatively high propylene by-product credit
due to unusually high propylene prices prevalent when the projects were
announced in the boom years for petrochemicals. However, the erosion in
propylene prices could act as a dampener for the proliferation of MTO/MTP
plants in China. The key for the technology is low delivered methanol prices.
'Green' propylene
Further down the horizon are the so-called 'green' propylene
technologies, which aim at producing the olefin using sustainable feedstock
such as biomass (through gasification), via ethanol or butanol (produced by
fermentation) or by the cracking of vegetable oils. These routes all vary with
respect to feedstock (food crop versus bio-waste), process complexity (number
of steps), and experience (commercially used process steps versus steps still
needing development).
Production economics for many of the alternate processes
based on renewable raw materials render them outside the realm of possibility
for the moment.
But they are a pointer that propylene for the chemical
industry of the future could well come from sources other than a barrel of
crude.
Source:
Chemical Weekly
