Considering the range of petrochemicals used crosswise for preparing a wide range of marketable products, including textiles, detergents, adhesives, antifreeze, solvents, and pharmaceuticals, what state-of-the-art catalysts are emerging for production of petrochemicals such as styrene, polymers, and aromatics?Mar-2023
Pierre-Yves Le Goff, Axens, Pierre-Yves.LE-GOFF@axens.net
The most important building block molecules for the downstream aromatics derivatives value chain are benzene (BZ) and paraxylene (PX). BZ is mainly used for styrene production, polyamide, and polycarbonate, while PX’s principal usage is for polyethylene terephthalate production.
While BZ can also be produced by the naphtha steam cracker unit, the vast majority of PX is obtained from the conversion of naphtha catalytic reforming effluent, namely reformate. The reformate conversion plant is commonly called an aromatics complex and employs multiple catalytic upgrading processes, fractionation sections and purification units, resulting in intense capital and operational costs.
With market trends pushing for continuous effort in maximising both profitability and reducing the carbon footprint of PX production, it is essential to deploy advanced molecular and energy management supported by leading catalysts and processes.
Particularly, there is a rising interest in combining liquid phase xylenes isomerisation (LPI) and gas phase ethylbenzene reforming xylenes isomerisation (EBR) in the xylenes final conversion block to unlock significant reduction of capital and operational expenditures on the aromatics complex. Feedstock requirements are drastically lowered, leading to further substantial savings on upstream preparation units. This also improves profitability, increasing the yield of highly valuable molecules only: PX and BZ, especially PX. Finally, LPI units present an intrinsically lower carbon footprint when compared with traditional vapour phase xylenes isomerisation units.
The newest scheme involving LPI, which can be implemented in existing aromatic complexes, provides improved economics and reduced GHG emissions. To push further PX production selectivity from a given fossil feedstock while incorporating lower carbon footprint sourced methanol, an aromatics alkylation process can also be considered.