How MaxFlux™ outperforms conventional hydrotreating technology

Introduction

Plastic pyrolysis oils (PPO) are a promising route to close the loop on plastic waste, but their complex mix of contaminants makes purification a serious technical hurdle for refineries and petrochemical plants. Traditional trickle-bed hydrotreaters, long used in refining, struggle to efficiently upgrade these oils.

That’s where Sulzer’s MaxFlux™ hydrotreating technology steps in offering a new standard in efficiency, robustness, and product quality.

MaxFlux™ vs. traditional trickle-bed hydrotreaters

Common challenges with trickle-bed systems:

• Hydrogen Diffusion Limitations: in conventional systems, hydrogen must move from the gas phase into the liquid, restricting reaction rates and reducing overall contaminant removal.

• Thermal Management Issues: managing exothermic reactions requires injecting quench hydrogen between catalyst beds, adding complexity and increasing utility costs.

• Complex Gas Circulation: recirculating large volumes of hydrogen gas demands additional compressors, piping, and costly energy input.

• Flow Distribution Problems: ensuring uniform feed and hydrogen mixing across the catalyst bed is difficult, potentially causing bypassing and incomplete upgrading.

  
  

The MaxFlux™ advantage:

• High Liquid Flux Operation: MaxFlux™ dissolves hydrogen fully into the liquid at the reactor inlet, erasing mass transfer limitations and maximizing intrinsic reaction rates throughout the catalyst bed.

• Stable Thermal Control: the large liquid volume acts as a “thermal buffer,” absorbing exotherms, minimizing temperature spikes, and reducing the risk of over-cracking or unwanted byproducts.

• No Gas Recycle Loop Required: with hydrogen fully dissolved up front, MaxFlux™ eliminates the need for gas recycle circuits, compressors, and associated controls cutting CAPEX and OPEX.

• Optimized Reactor Internals: custom mixing and distribution ensure every part of the catalyst bed is active, extending catalyst life and ensuring product consistency.

  
  

Measurable performance improvements

Sulzer MaxFlux™ consistently exceeds the performance of conventional hydrotreating for PPO purification:

Contaminant	Typical PPO Feed	Steam Cracker Spec	MaxFlux™ Product
Nitrogen (ppmw)	400-1,500	<100	<10
Sulfur (ppmw)	30-200	<500	<50
Silicon (ppmw)	35-50	<1	<1
Chlorine (ppmw)	30-150	<1	<3
Olefins (wt%)	45-55	<1	<2
Metals (ppmw)	25-50	<1	<1

• Longer Catalyst Life: gentler process conditions reduce coking and deactivation, lowering maintenance costs.

• Higher Yields, Less Overcracking: stable temperature profiles mean more naphtha, less gas, and superior end-product yields.

• Lower Utilities: by eliminating the gas recycle loop and requiring fewer compressors, MaxFlux™ shrinks energy bills and plant footprint.

  
  

Real-World impact

Plants upgrading to MaxFlux™ report:

• Immediate compliance with even the strictest downstream cracker specifications

• Simpler operation, less downtime, and reduced need for corrective maintenance

• Flexible adaptation to variable-quality plastic waste feeds

  
  

Conclusion

Sulzer’s MaxFlux™ hydrotreating technology isn’t just an upgrade from standard trickle-bed designs it’s a total re-imagining of how to process challenging plastic-derived oils.

For any operator seeking reliable contaminant removal, improved economics, and product flexibility, MaxFlux™ is the proven, future-ready solution.