Back

Question

Submit an Answer

What optimal mass transfer/product separation configurations benefit the integration of catalytic reforming and aromatics complexes?

Apr-2025

Answers

Sidhartha Aggarwal, Honeywell UOP, sidhartha.aggarwal@honeywell.com

Molecule management, particularly molecular precision, is one of the most critical aspects in optimising integrated catalytic reforming and aromatic complexes. The process begins with optimised separation in the naphtha splitter column. This ensures that all aromatic-generating molecules, preferably rich in C6 to C8 hydrocarbons, are routed into the heavy naphtha stream while minimising lighter or non-naphthenic paraffins to reduce catalytic cracking and the resultant, lower-valued byproducts in the downstream complex.

UOP’s proprietary CCR Platforming process employs specialised catalysts to maximise the conversion of heavy naphtha into aromatics. The main product from the Platforming unit is reformate, which is rich in aromatics components. In addition, byproducts such as fuel gas and co-products such as hydrogen and LPG are generated in the Platforming unit, which may have different applications depending upon the refinery configuration and needs. The reformate is further fractionated in the Platforming unit using debutaniser and/or depentaniser columns to remove low-value lighter hydrocarbons (C5 and lighter), simplifying downstream processing and lowering installation and maintenance costs.

The C7- fraction from the reformate splitter proceeds to the proprietary UOP Extractive Distillation (ED) Sulfolane process, which utilises tetrahydrothiophene 1,1-dioxide (Sulfolane) as a solvent. This method effectively recovers high-purity benzene and toluene from hydrocarbon feeds, requiring less than 80% of the capital investment compared to traditional liquid-liquid extraction.

Incorporating a proprietary Tatoray unit into an aromatics complex can significantly boost the yield of PX from naphtha. By feeding A9 and A10 byproducts with toluene into the Tatoray unit, additional methyl groups shift the chemical equilibrium from benzene production to xylenes, facilitating the production of mixed xylenes from low-value toluene and heavy aromatics.

The proprietary UOP PX-Plus process selectively disproportionates toluene to produce benzene and xylenes, achieving a paraxylene concentration of about 90%, considerably higher than the 25% equilibrium achievable through transalkylation technologies like Tatoray. The proprietary Parex process uses adsorptive separation to recover paraxylene from mixed xylenes, notably employing a solid zeolitic adsorbent (ADS-50) in a continuous format that simulates counter-current flow.

The benzene-toluene fractionation (BTF) unit, featuring a dividing wall column (DWC) design, separates benzene, toluene, and xylenes in a single vessel, optimising plot size and reducing both capital and energy costs while enhancing product purity. Finally, the xylenes fractionation unit is crucial for recovering xylene feed for the Parex process and light aromatics for Sulfolane. This unit includes multiple columns and is highly integrated with other plant sections for energy efficiency, utilising MD trays and proprietary High Flux tubes to maximise utilities and reduce capital investments.

Apr-2025