Q & A > Question Details
With regard to application of catalysts in Isomerisation process, I would like to know about the overall comparison between tradition catalyst i.e. Aluminium Chloride and novel catalysts based on platinium element. In point of view of economical criteria which case has been suggested?
11/11/2011 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Aluminium chloride type catalyst are not used for isomerization technologies now.
Modern typical commercial isomerization technologies are C4 Isomerization, Light Naphtha Isomerization, C8 aromatics Isomerization, Lube Hydroisomerization, Wax Hydroismerization. None of them use aluminium chloride catalysts. The major catalyst vendors and technology suppliers for such processes are UOP, Axens, Exxon Mobil.
07/11/2011 A: Steve Metro, UOP, steve.metro@uop.com
There are several types of light naphtha isomerization processes and corresponding Pt containing catalysts available in the market today. Earlier process generations such as UOP’s TIP TM Total Isomerization process included a fixed bed technology employing a zeolitic based catalyst such as UOP HS-10 isomerization catalyst (still available today). Today, there are 2 primary commercially proven process and catalyst options: UOP’s ParIsomTM process employing UOP’s PI-244 catalyst and UOP’s Penex TM process employing UOP I-82 Isomerization Catalyst. Both solutions provide a high octane product at high yields, excellent benzene conversion, and cost effective means to upgrade naphtha.
A chlorided alumina type catalyst (used in the UOP Penex process or similar) will provide the highest activity, yield, and conversion vs. a sulfated zirconia type catalyst (used in a UOP ParIsom process or similar) for a C5/C6 isomerization application. However, a sulfated zirconia type catalyst is relatively tolerant to contaminants vs Penex type, is regenerable, and does not require chloride injection to maintain activity. There are pros and cons to both process/ catalyst types and many factors must be considered for a given application in a refinery. Please note that these catalyst types are not interchangeable and some process unit revamp work would be required to convert operations to a different catalyst type. It’s recommended to discuss these options with a leading process and catalyst supplier such as Honeywell’s UOP LLC.
The information in this response should not be construed as a representation for which UOP assumes legal responsibility, or an authorization or recommendation to practice a patented invention without a license. © UOP LLC 2011, All Rights Reserved
07/11/2011 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
An excerpt from my course manual:
Isomerization of light naphtha from the crude unit was intended to increase the octane for improved blending. Today, the process provides the additional benefit of saturating benzene, now an undesirable component in gasoline. The unit consists of a charge heater, reactor, fractionation, and sometimes recycle hydrogen. Approximately 84 RON can be achieved, or 90 RON with a recycle section. In this case, a recycle section means liquid recycle through either a deisohexanizer or a molecular sieve unit for iso/normal separation. The most profitable catalyst is chlorinated alumina because it provides the highest RON and requires no recycle compressor. This catalyst is water intolerant and is typically not regenerated. Chloride is injected to maintain catalyst activity.
A different catalyst, with a zeolitic base, can tolerate up to 100 ppm water in the feed, but operates optimally at lower water content, i.e., with fractionator drying. Zeolitic catalysts can be regenerated and can tolerate sulfur. However, on a once-through basis, zeolitic catalysts produce an octane boost approximately 5 numbers lower than can be achieved with chlorided catalysts. The lower octane boost is the result of a lower operating temperature, producing fewer branch chained molecules.
Another catalyst, a sulfated metal oxide catalyst, is also water tolerant and regenerable. Oxide catalyst can tolerate 5-10% benzene in the feed with reasonable run lengths.
When the benzene content of the feed exceeds 5%, UOPs Penex Plus™ may be justified. The process consists of including a pre-reactor containing a noble metal catalyst to convert benzene to cyclohexane. Penex feeds with benzene contents of over 30% have been experienced.
With zeolite catalyst, as the C7 content increases, the octane decreases.