The two main sources of propylene are as a byproduct from the steam cracking of liquid feedstocks such as naphtha as well as LPGs, and from off-gases produced in fluid catalytic cracking (FCC) units in refineries. The remainder of propylene is produced using on-purpose technologies such as propane dehydrogenation (PDH) and metathesis.
The primary source of propylene is from cracking naphtha and other liquids such as gas oil and condensates to produce ethylene. By altering the cracking severity and the feedstock slate, the propylene:ethylene ratio can vary from 0.4:1 to 0.75:1. Smaller amounts of propylene can be obtained from cracking propane and butane. The cracking of liquid feedstocks is carried out predominately in Europe and Asia but less so in the Middle East and North America.
A growing source of propylene, particularly in the US, is from refineries where splitters recover the propylene from the off-gases produced by FCCs. However, refinery propylene needs to be purified for chemical and polymer use. New catalysts are now available that increase propylene output from the FCCs.
With propylene demand growing faster than ethylene, combined with the building of more ethane crackers (which produce no propylene) rather than naphtha crackers, on-purpose technologies are being employed increasingly to make propylene. The main on-purpose process used is propane dehydrogenation (PDH) but it is only economically viable in cases where low-cost LPGs are available. Propane is converted to propylene at 500-700oC in a reactor containing a nobel metal catalyst.
Although PDH technology is reasonably well established, the main criticisms of this route are relatively high capital costs and the need for a long-term, low-cost supply of propane such as available in the Middle East. New processes are being developed that claim to lower both capital and operating costs.
Much effort is being put into increasing propylene output from liquid steam crackers and FCC units. For example, the BASF-Fina cracker at Port Arthur, Texas, employs a metathesis unit to boost propylene output. Metathesis is the catalytic conversion of ethylene and butene-2 into propylene. However, these units need access to large C4 streams that are free of isobutylene and butadiene.
The Superflex process, originally developed by Arco Chemical and licensed by Kellogg Brown & Root, converts light hydrocarbons in the C4 to C8 range into a propylene-rich stream. Deep catalytic cracking (DCC), developed by China's Sinopec and offered by Stone & Webster, produces light olefins from heavy vacuum gas oils and de-asphalted oils.
ExxonMobil has developed an olefins interconversion (MOI) technology that uses the ZSM-5 zeolite catalyst to convert C4s, light pygas and light naphtha into propylene and ethylene using a fluidised bed. By contrast, Lurgi employs a fixed bed catalytic reactor that converts C4 and C5 olefins into propylene and ethylene.
While the methanol-to-olefins (MTO) process is normally seen as a way of boosting ethylene output, the flexibility of the process allows for propylene production to increase to 45% of total output.
Total in conjunction with UOP has further boosted propylene output by developing an olefin cracking process (OCP) which takes the heavier olefins from the MTO unit and converts them into lighter olefins, in particular propylene. The integrated MTO/OCP process, which is being tested in a pilot plant in Feluy, Belgium, produces significantly more propylene than ethylene.
Lurgi is developing a process that converts methanol to propylene (MTP) and, in conjunction with Statoil, operates a pilot plant in Norway. The MTP process is expected to be used in China converting methanol produced from coal into propylene and in Trinidad where the methanol will ultimately be used to make polypropylene.
Propylene
Price Reports
ICIS pricing gives you access on a weekly or real time basis to the latest price movements and critical market commentary on the Propylene market. Click below to see a quarterly market overview.
More about Propylene Price Reports
Propylene
Uses and Outlook
The dominant outlet for propylene is polypropylene (PP), accounting for around 63% of global propylene consumption. PP is one of the most versatile of the bulk polymers due to a combination of good mechanical and chemical properties. Hence its applications are very wide.
More about Propylene Uses and Outlook
Search for
Propylene
Suppliers
If you are sourcing
Propylene
products and services, use ICIS search for fast and accurate results. ICIS search
is the search engine dedicated to the chemical industry – we show you only relevant
results -
search now.