Intratec Chemical Process Library is the first free online encyclopedia of chemical process technologies. Our Library covers not only processes description themselves, but also the economics surrounding chemicals manufacture, providing real-world knowledge on the production of several chemical commodities. Click here to check all chemicals covered.
In this page you will find free data about Propylene, including:
- What is Propylene
- How to make Propylene
- Propylene uses and applications
This page presents brief synopsis of Propylene production technology, describing, in a concise way, relevant technical and economic aspects. Each manufacturing process description will consist of:
- Major process steps
- Simplified, schematic flow diagram & key equipment
- Important safety or environmental considerations
- Economic perspective, comprising capital expenditures and/or operating expenses
All content from Intratec's Chemical Process Library was produced based on reports published by Intratec. To learn more about Propylene production processes presented below and others examined in Intratec reports, click here.
Propylene Manufacture via Propane Dehydrogenation - Similar to UOP Oleflex Technology
Because natural gas supplies are significantly increasing due to the rising exploitation of shale gas, mainly in the U.S., propane prices are decreasing. Coupled with low propane prices, ethylene producers are shifting to lighter feedstocks (more ethane, less naphtha), which is decreasing yields of propylene in cracking operations. The increasing demand for propylene and the availability of low-cost feedstock make propane dehydrogenation an economically attractive chemical route.
Propane, the main feedstock for propane dehydrogenation (PDH) processes, can be obtained as a byproduct of petroleum refinery operations and can be recovered from propane-rich liquefied petroleum gas (LPG) streams from natural-gas processing plants.
PDH is an endothermic equilibrium reaction. The PDH process depicted below is similar to the Oleflex process developed by UOP LLC (Des Plaines, Ill.; www.uop.com), and is suited to produce polymer-grade (PG) propylene from propane. The maximum unit capacity is around 650,000 ton/yr. This process is carried out in the presence of a platinum catalyst and achieves overall propylene yields of about 90 wt.%.
The industrial plant can be divided into two main sections: reaction and product recovery.
In the reaction section, after heavy impurities removal in the de-oiler column, propane is sent to the dehydrogenation reactors. The propylene yield in such reactors is favored by higher temperatures and lower pressures. However, temperatures that are too elevated will promote thermal cracking reactions that generate undesirable byproducts. Therefore, the PDH reaction usually occurs at temperatures of about 650°C and near atmospheric pressures.
In order to purge the coke accumulated on ...
An economic evaluation of the process was conducted based ...
Propylene Manufacture via Propane Dehydrogenation, Similar to CB&I Lummus CATOFIN Technology
PDH reaction is an endothermic catalytic process that converts propane into propylene and hydrogen. The figure below illustrates a technology similar to the Catofin process, by Lummus Technology, which uses fixed-bed reactors and a chromium-based catalyst. It is carried out in two main areas: reaction and regeneration; and product recovery. The yield of propylene is about 85 wt.%. The reaction byproduct (mainly hydrogen) are usually used as fuel for the reaction. As a result, propylene tends to be the only product, unless local demand exists for the hydrogen byproduct.
Reaction and Regeneration Section
Fresh propane feed is mixed with recycled propane from a propylene-propane splitter. This stream goes to a de-oiler for impurities removal and then is carried to the reaction step, which is continuous and operates in cycles. In this step, multiple reactors undergo a controlled sequence of reaction, catalyst reduction and catalyst regeneration.
Product Recovery Section
In this area, there is a low-temperature ...
Propylene Manufacture via Propane Dehydrogenation, Similar to Uhde STAR Technology
The PDH process is similar to the STAR (steam active reforming) process (Uhde GmbH; Dortmand, Germany; uhde.co.za), which applies the oxydehydrogenation principle.
The STAR process was the first to apply the oxydehydrogenation principle for propylene production, significantly enhancing its performance. In this technology, oxygen is added to the system to react with hydrogen, forming water. This reaction lowers the hydrogen partial pressure, shifting the equilibrium to higher conversion of propane into propylene while providing the required heat of reaction. The chart shows the effect of oxygen addition on propane conversion, according to different oxygen-to-propane molar ratios.
Propane is fed into a depropanizer ...
Propylene Manufacture via Metathesis
Metathesis, also known as disproportionation, is a reversible reaction between ethylene and butenes in which carboncarbon double bonds are broken and then rearranged to form propylene. Both ethylene and 2-butenes are mainly supplied from steam-cracker units, but can also be obtained from FCC units. The metathesis process depicted in the figure is similar to the OCT (Olefins Conversion Technology) process developed by Lummus Technology (part of Chicago Bridge & Iron Co. N.V.; the Hague, The Netherlands; www.cbi.com) and makes use of a tungsten oxide catalyst, along with a magnesium oxide co-catalyst. The OCT process typically achieves a propylene yield of about 90%.
The process is divided into two main areas: purification and reaction; and separation.
Purification and Reaction
Fresh and recycled ethylene and butene are mixed and fed to treatment equipment that removes potential catalyst poisons, such as oxygenates and sulfur. After treatment, the stream is vaporized and heated to the reaction temperature, between 280 and 320°C. The metathesis reaction occurs ...
The MTP process consists basically of two reaction steps: an initial one to dehydrate methanol to dimethyl ether (DME) on an aluminum oxide catalyst, and a second one to transform DME and methanol into a variety of olefins, ranging from ethylene to octenes. However, using a zeolite-based catalyst (ZSM-5), the process yields mainly propylene. A set of purification columns is necessary to obtain the polymer-grade (PG) propylene. The figure illustrates a process similar to the ones licensed by Lurgi GmbH (the MTP process; Frankfurt am Main, Germany; www.lurgi.com) and JGC Corp. (Yokohama, Japan; www.jgc.co.jp) and Mitsubishi Chemical Corp.’s (Tokyo; www.mitsubishichemical.com) DTP process, which can be divided into three main areas: reaction and regeneration; quench and compression; and product fractionation.
Reaction and Regeneration
In this stage, the methanol feed is vaporized, mixed with recovered methanol and dimethyl ether (DME), superheated and sent to the DME reactor, where dehydration occurs.
The product is mixed with recycled ...
An economic evaluation of the process was conducted based on data from the fourth quarter of 2012. The following assumptions were taken into consideration:
- A 560,000 ton/yr unit erected on the U.S. Gulf Coast (the process equipment is represented in the simplified flowsheet)
- There is no storage for feedstock and product
- Outside battery limits (OSBL) units considered: propylene refrigeration system
The estimated capital investment (including total fixed investment, working capital and other capital expenses) to build the MTP plant is about ...