Page 136 - CW E-Magazine (15-10-2024)

Point of View

About 40% of global demand is in China – not surprising considering the mammoth capacities for making commodity & speciality
isocyanates and PC. Demand there is expected to grow at a CAGR of ~6% to 2030 – well above the global average.

The leading producers of phosgene are Covestro (24% of global capacity), Yantai Wanhua (22%), and BASF (18%).

Only about 5% of phosgene demand is accounted for by a slew of chemistries that make the chemicals needed for pharmaceuticals
and agrochemicals, amongst others.

India’s phosgene industry
India’s consumption pattern for phosgene is very different from the rest of the world. While there is no production of MDI here
(though BASF operates an MDI splitter that processes crude MDI, imported from its plants abroad, to produce polymeric and monomeric
MDI cuts), GNFC does operate two plants producing TDI – one with a capacity of 10-ktpa and another 50-ktpa. Due this, GNFC is the
largest producer of phosgene in India. As of now, India has no plant for making PC resin, though one could be forthcoming.

As a consequence, a sizeable chunk of phosgene is produced and consumed in India for making several smaller volume chemicals
by the likes of Atul, Paushak, and UPL. These include chloroformates (made by the reaction of phosgene with alcohols); carbonate
esters such as dimethyl/diethyl carbonates (used as to make pharmaceuticals and agrochemicals), and diphenyl carbonate (used to
make PC); as well as a range of ketones produced by Friedel-Crafts acylations with phosgene.

The Pharmaceuticals and Intermediates Business of Atul, for example, uses phosgene to produce chloroformates, isocyanates
and organic ureas, that go to make a range of active pharmaceutical ingredients (APIs), technical agrochemicals and speciality
chemicals. Paushak, part of the Alembic Group, claims to be the largest producer of phosgene-based speciality chemicals in India,
including chloroformates, carbamoyl chlorides, carbamates, protecting agents, etc. The company claims (on its website) a phosgene
manufacturing capacity of 14,400-tpa, and a status as the oldest manufacturer of phosgene in the country.

Process and safety systems
From a manufacturing standpoint, the focus at all phosgene producers – be it in India or abroad – is on building robust processes
and safety systems that minimise the risks to the maximum extent possible. A great deal of thought goes into the design of phosgene
plants, its build-up, start-up, continuous operation, and periodic maintenance. Every aspect of the plant – its general design, layout & siting,
materials of construction, piping & valve selection, instrumentation, relief devices, secondary containment, and mitigation systems – are
all precisely documented and refined periodically to reflect operator experiences.

Several secondary technical measures are used to detect leaks as soon as possible and to combat escaped phosgene. These
include, e.g., continuously operating alarm systems for monitoring room air and ambient air; systems for combating escaped phosgene
by chemical reaction (e.g., steam-ammonia curtains in the case of gaseous emissions); jacketed pipes; and complete containments
for phosgene processing plants or plant units. Leaks of liquid phosgene can be somewhat easier to tackle, e.g., by covering it with
sorption and destruction agents.

Improved safety record
Thanks to all these, and diligent operations, the track record of safety in the global phosgene industry has improved. Since 2021,
there has been only one fatality at a plant in Hungary (owned by Indian promoters), but that is still one too much. It is regretful that
out of the 22 fatalities since 2010 in the global phosgene industry, 13 have been in India. What is also a matter of concern is that
while fatalities have come down, reportable incidents (with no fatalities) have become more frequent. Learnings from conferences
such as the one conducted by the IPC are very relevant as they enable Indian phosgene producers learn from mistakes others have
made and adopt the recommendations in their day-to-day manufacturing and maintenance operations.

Phosgenation is a niche and versatile technology that Indian companies are looking to scale-up to benefit from contract manufacturing
opportunities expected to come their way. The industry here has bright prospects but will need to stay eternally vigilant to maintain a good
safety record.
Ravi Raghavan

136 Chemical Weekly October 15, 2024

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