Hydrocarbon Engineering

BREAK

THROUGH

March

2017

HYDROCARBON

ENGINEERING

olypropylene is the leading high performance

plastic used for a wide range of durable plastics

used in the automotive, electronics, and many

other industries due to its high performance

characteristics. Additionally, polypropylene is easily

recycled, resulting in far less of an environmental impact

than many other widely used plastics.

Polypropylene is produced via the polymerisation of

propylene. Approximately 55% of the global propylene

supply has been traditionally produced as a by-product

from the steam cracking of naphthas and 35% of the global

supply via the catalytic cracking of heavy oils in fluidised

catalytic crackers (FCC). The remainder is produced from

on-purpose propylene processes such as propane

dehydrogenation (PDH), metathesis, coal-to-olefins,

methanol-to-olefins, etc.

A typical steam cracker processing naphthas will

produce approximately 17 wt% propylene. Many steam

crackers in the US have been retrofitted from naphtha to

ethane as feedstock due to the rapid development of

fracking, which has produced a large surplus of natural gas

liquids (NGLs). A typical ethane-based steam cracker will

produce less than 5 wt% propylene, sometimes as low as

2 wt%. This has resulted in a shortage of propylene in many

regions of the world. Since export restrictions for

hydrocarbons from the US have been lifted, this trend is

expected to spread worldwide. Separately, in various parts

of the world, studies on the impact of fracking have

started, which could improve availability of ethane rich

feedstocks in Europe.

Many motor fuels-based FCC units have shifted their

operations from solely gasoline to maximum propylene,

which increases propylene yield from 4 – 5 wt% to

7 – 9 wt%, with a maximum of approximately 12 wt%.

Alternatively, a refiner may choose to employ a more

aggressive approach and revamp its standard FCC for

Making

Ray Fletcher, InovaCat B.V.,

the Netherlands,

presents

a new technology capable

of converting low valued

naphthas into maximum

propylene and BTX.