Case study

Improving Operator Safety in API Catalyst Recovery

Pharma

Product

SupaClean

Client

Multinational Pharmaceutical API Manufacturer

Application

Capture of Palladium on Carbon (Pd/C) Catalyst

Location

Spain

Value Added

Elimination of operator exposure to catalyst and solvents

Sector

Pharmaceutical

The Application

Catalysts are used extensively to initiate and promote the chemical reactions required to synthesise new chemical entities in the pharmaceutical industry. Following their use, they have to be removed from the fluid stream and disposed of. From both an environmental and cost perspective, it is prudent to implement strategies to reclaim as much of the rare metals ( Palladium, Platinum, Rhodium and Ruthenium) as possible.

How many companies are actively engaged in reclaiming these rare metals is difficult to ascertain, but it is definitely a practice that will have more focus in the near future as companies show commitment to developing more sustainable production practices. 

We have recently been working closely with a number of pharmaceutical companies engaged in developing processes to capture catalyst. The focus has been on increased health and safety for the operators in addition to guaranteeing high efficiency catalyst capture. 

The Separation Technology

The method by which the catalyst is removed from the pharmaceutical intermediate is dependant on the form of catalyst. They are typically divided into either heterogeneous or homogeneous form. In this case study we are dealing with heterogeneous catalysts that can be removed by physical filtration.  

Heterogeneous catalysts are solid catalysts used in reactions where the reactants are in a different phase, typically liquid. These are favoured due to the relative ease of separation from the reaction mixtures.

  • Palladium on Carbon (Pd/C) : Widely used for hydrogenation reactions
  • Platinum on Carbon (Pt/C) : Employed in hydrogenation and oxidation processes
  • Rhodium on Alumina (Rh/Al2O3) : Used in hydroformylation reactions
  • Ruthenium on Carbon (Ru/C) : Applied in various hydrogenation reactions

The Problem

Once used in the synthesis, the catalyst needs to be removed for subsequent disposal or recycling in a safe and efficient way. Spent palladium catalyst can pose a number of health and safety risks such as 

  • Toxicity of palladium compounds 
    • palladium salts and complexes can be toxic if inhaled or ingested
  • Exposure to organic solvents
    • Palladium catalysts are often used in solvent based reactions e.g. toluene / THF / dichloromethane. 
  • Dust and Particulate inhalation
    • Spent catalyst can be in the form of fine dust 
  • Fire and Explosion risk
    • Pd/C is pyrophoric ( can self combust with exposure to air) Catalyst should be kept damp with with water purge or in residual solvent
    • residual solvents and reactants may present additional flammability risk
  • Reactivity Hazards 
    • Improper neutralisation or containment could result in thermal runaways 
  • Waste Handling and Contamination
    • Handling of spent catalyst must adhere to hazardous waste protocols
    • Potential for operator exposure

Traditional methods for recovering or capturing spent catalysts include, but are not limited to, manual plate filters, filter presses, bags or lenticular cell filters.

The main problem with these technologies is potential operator exposure once the catalyst has been captured. So how do you capture the catalyst and remove it from the process while minimising or eliminating operator exposure?

Customer Application Details

This particular process used a Palladium on Carbon (Pd/C) catalyst (5 % wt. loading on an activated carbon matrix). This is supplied wet (50% water), then mixed with Methanol for use in the reaction vessel. 

The customer traditionally used filter bags to capture the catalyst, but this method had inherent associated health and safety issues. Filter change outs increased the risk of operator exposure and made subsequent re-packaging for off-site processing complicated. 

An Improved Method of Catalyst Capture 

The  SupaClean filter system was introduced in place of the existing bag filter design. It is designed specifically to eliminate operator exposure. It also has the additional benefit of simplifying the onward handling and transportation of the catalyst for subsequent recovery of the valuable palladium.

Working closely with the customer resulted in the manufacture of a specially modified SupaClean system, utilising 7 off  20" SupaSpun II filters in a 30" length SupaClean housing. The additional free volume available allowed up to 3 kg of concentrated catalyst slurry to be retained.

The video below shows the retained catalyst being removed from the SupaClean housing.

The SupaClean Advantage

The SupaClean system provides an elegant solution to improve the health and safety of catalyst removal.

  1. Following filtration of the catalyst slurry low pressure compressed nitrogen can be introduced via the integral tapping on the side of the SupaClean housing. This collapses the internal flexible containment bag and purges out residual carrier solvent.
  2. The SupaClean filter inlet and outlet connections are then capped off securely ensuring the catalyst remains 'wet' in the filter to prevent any risk of combustion as the catalyst is pyrophoric.
  3. The SupaClean housing can be supplied in a customised 'cradle' that allows the housing to pivot to further improve health and safety with respect to manual handling.
  4. The SupaClean filter system can accommodate any of the Amazon Filters range of cartridges. This ensures the required filtration efficiencies can be matched to the size of the catalyst particle size.
  5. The flexible bag used in the SupaClean filter is available in various materials to ensure chemical compatibility.
  6. Feedback from companies recovering the palladium or other rare metal from the catalyst say that the SupaClean format also substantially simplifies health and safety implications at their own facilties.

For more detailed information on the product click here SupaClean.

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