|  | TransPlus (Heavy Aromatics Transalkylation)
Profitable Heavy Aromatics Processing
The low-cost, high-conversion solution to effectively transalkylate C9 + heavy
aromatics and toluene/benzene into higher value mixed xylenes and high-purity
benzene is the TransPlus process. It utilizes a proprietary catalyst working
with improved process technology, co-developed with and commercialized by the
Chinese Corporation (CPC) of Taiwan. TransPlus(sm) services provide full
support for licensees from initial consultation through technology transfer
and on-going improvements.
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High feedstock flexibility
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Longer cycles and enhanced product selectivity
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Capital savings: Retrofit or grass roots
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A simple fixed bed process
High Feedstock Flexibility
With the ability to vary the toluene to heavy aromatic ratio in the feed, the
TransPlus process offers a high degree of flexibility and profit-maximizing
potential. The TransPlus process can effectively co-process a high level of
C9+ aromatics, with either toluene or benzene. Fresh feed composition can be
varied from 100% toluene to 100% C9+ aromatics. This gives refiners increased
latitude to optimize the disposition of the C9+ aromatics stream by enabling
incremental production of mixed xylenes while reducing the heavy aromatics
content in gasoline in order to meet reformulated fuel requirements or
distillation specifications.
TransPlus Chemistry
| Longer cycles and enhanced product selectivity
Unlike other transalkylation processes that have relatively strict feed
specifications, the TransPlus process utilizes a unique catalyst that has a
higher tolerance to heavy aromatic impurities which cause catalyst aging. So
proven cycle lengths of several years can be readily attained using the fully
regenerable catalyst.
In addition, the higher selectivity of the catalyst allows for flexibility to
vary the fraction of the C9+ aromatics in the feed giving operators the option
to change the benzene/xylene product to meet market conditions or product
demand. Refiners can also adjust their feed composition based on the pricing
differential between toluene and C9+ aromatics.
The first commercial transalkylation unit was started up in mid-1997 at CPC's
Lin-Yuan petrochemical plant, where an existing competitor transalykation unit
was converted to TransPlus. As a result of the conversion, CPC observed that
xylene yield increased by 30% and utility consumption was reduced by 20%.
Capital savings: Retrofit or grass roots
The higher weight hourly space velocity (WHSV) and lower
hydrogen-to-hydrocarbon mole ratio and higher conversion of C9+ aromatics
relative to competitor processes, make it possible to readily retrofit the
TransPlus process into existing units that have limited reactor volume or
compressor capacity. This can result in a lower cost debottleneck
alternative. And those same characteristics lower the capital investment for
grass roots installations.
Other benefits include:
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Lower operating costs
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A C8 aromatics product slate that is low in ethylbenzene providing further
potential debottleneck of the downstream paraxylene recovery facility
A Simple Fixed Bed Process
The process flow is typical for a vapor phase reaction in a fixed bed reactor.
C9+ aromatics feed, along with toluene combined with a hydrogen-rich recycle
gas, is preheated and passed through a catalyst bed. In the catalyst bed,
deethylation and disproportionation/transalkylation occur at moderate
temperature and pressure to produce equilibrium-mixed xylenes and benzene
and/or toluene, depending on the feedstock. By-product yields are small.
The reactor effluent is cooled by heat exchange and the liquid products are
separated from the recycle gas. The separated liquid is stripped to remove the
light ends and then fractionated to recover the benzene product and the mixed
xylenes product.
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