Advertorial: Catalyst Recovery – A win-win for business, people, and the environment
Chris Boulton, Sky Metal Services
Catalyst Recovery – Why?
You are running a chemical plant. You manufacture a product and everything you do is dedicated to producing in the most efficient way possible. You maintain your plant, purchase the raw materials, run your process, and ship your product to your happy customers. In the middle of all of this is metal catalyst. Often very expensive and complex material which can get lost. Lost catalyst means lost metal and lost value. Some examples in the petrochemicals industry are as follows:
Petroleum refining: A petroleum refinery will have precious metal catalysts in the naphtha reformers which turn naphtha into gasoline components and chemical feedstocks A reformer loaded with 100 tons of a 0.2 wt% Pt-Re/alumina contains 200 kg of Pt worth around $7 million at today’s prices. This value can go by the wayside given that a refinery will be looking to sell at least two-orders of magnitude higher in products every day!
Fine Chemicals: 5 tons of a 5 wt% palladium on carbon catalyst – a typical catalyst which might be supplied for a fine chemical or drug active synthesis – contains 250 kg of the precious metal currently worth around $14.6 million. Every 1% loss equates to $146,000. If a plant is running multiple catalyst reactors, this can add up to a significant amount of money each year!
Ethylene oxide (EO) production: EO is a key intermediate in the production of monoethylene glycol (MEG), which in turn is used to make polyethylene terephthalate (PET) for beverage bottles, clothes, and textiles. The process involves the epoxidation of ethylene over a high-metal loading silver/α-alumina catalyst loaded into tubular reactors. A typical plant can contain as much as $40 million worth of silver at current prices. Because of the very large mass of catalyst and reactor geometry, removal can be tricky resulting in crushed, chipped and severely damaged catalyst pellets which can block the reactor and create significant amounts of dust upon catalyst removal – a recipe for significant catalyst losses if the correct procedures are not employed.
Who is responsible for managing the catalyst?
Catalyst must be purchased, supplied, handled, used, and replaced. Functions shared by other materials in the plant, but recycling may be unique and does not always fall under a staff function, or supplier function, often not receiving the focus it should and ultimately impacting your business.
Why should I spend valuable resource on recovering catalyst?
A few years ago, a pharmaceutical manufacturer did a mass balance study which showed a loss of palladium based catalyst of 25%. That is a quarter of this expensive material simply disappearing somewhere between delivery and refining of the spent catalyst.
After a detailed assessment it was found that significant amounts of palladium were being deposited on the inside of the reactor. There were also handling issues which lead to the dark powder being distributed around the plant. Possibly the most shocking instance was the discovery of a sump which was collecting catalyst spillages. This had literally been forgotten about and the plant staff did not even know of its existence. When the material in the sump was recovered and refined the value was determined to be around $9 million. After management steps were implemented, losses were determined to be “at acceptable levels,” regular cleaning and monitoring helped to maintain an efficient management process.
Your catalyst is a valuable resource, both to your business and our planet. Let us consider the implications.
Finance. Your business in interested in making money but what about saving money? Catalyst is often expensive, sometimes very expensive – as outlined above even low percentage catalyst losses add up to a considerable amount of money straight off your bottom line. You can save time and human resources by disposing of spent catalyst without sending it for refining, however you are then also disposing of recoverable value. If you are using a precious metal catalyst, then this value can be considerable. The prices of metals, be it base metal or precious metal, have significantly increased in recent years. This increases the financial impact of catalyst on your business.
Environment. Your business is concerned about its environmental impact and even if you think there is no significant value in your spent catalyst and even if you are one of the thousands of businesses that only pays lip service to everything “green,” you really need to know about the environmental cost of catalyst management. More importantly, regulations pertaining to catalyst disposal including the EU Waste Framework Directive, the Basel Convention and various other international regulations on waste shipping and transboundary movement. We are all aware of the simple concept of recycling, however in the case of catalyst recycling has a double benefit of not only enabling the reuse of metals but also reducing the need for new metal being mined from the earth. The energy required to mine metal can be around 300 times that of refining existing materials. That is a huge amount of extra fuel and CO2.
Plant Efficiency. Your business runs an efficient plant, however catalyst residues can settle in your plant equipment and reduce efficiency. This presents another significant impact to your bottom line.
Three good reasons why. But how?
We are going to use the word “specialists” a lot here. As you will see, the knowledge and experience of specialists will add significant value to the recovery process and ultimately, your bottom line. Catalysts are a key part of the circular economy and in themselves, they require circularity as shown in Figure 1.
First, we need to acknowledge that all plants and processes are different. Therefore, understanding your plant, processes, materials, and catalysts are important to make an effective and efficient recovery plan. An assessment by experienced specialists is all that is required to gain this vital knowledge and produce an effective plan.
When it comes to physically managing the catalyst then there are several opportunities for material to be lost. Lost catalyst means lost value and lost resources.
Within the chemical plant itself, catalyst can gather in plant equipment including reactors, boilers, heat exchangers, extractors, and storage vessels. In addition, catalyst can end up in PPE, clothing, and cleaning materials and finally in packaging, handling, and shipping areas.
Removing and replacing the catalyst at end-of-life is one of the more obvious instances where material can escape the process so this must be managed correctly. Having operators covering the plant and themselves in catalyst dust can be considered a distribution of wealth but not one which helps your business. There are also clear health and safety issues with workers exposed to catalyst dust.
Should the assessment identify equipment that contains catalyst residues and testing has shown that there are volumes of material that make recovery necessary and viable (considering value of recoverable material and the effect on plant efficiency), then specialists in catalyst recovery from chemical plants can recover these residues quickly, efficiently and with minimal impact to the plant. They understand the plant processes and the impact that different techniques and downtime will have on production and will work with Management and Operations to ensure the work is carried out smoothly as well as prioritising health and safety.
The two biggest opportunities for catalyst/metal/value to be lost are usually during recovery and refining. Recovery needs to capture as much material as possible while refining needs to lose as little metal as possible.
Choosing the right refiner is sometimes a less obvious consideration. If we are considering efficiency, then simply returning the catalyst to the manufacturer may or may not be the most efficient option for your business. One of the biggest impacts to your business is the efficiency of the refinery and its suitability for your material. The refining processing steps involved in taking spent catalyst, residues, filters etc, and turning it in to metal and supplying you with fresh catalyst can be complex and will certainly vary from one refiner to another. The most suitable refiner should be considered at the planning stage to make the process as efficient as possible and maximise the amount of metal that gets back into your account. Accurate sampling of waste prior to refining is a key activity to ensure good agreement on metal content and to assess the efficiency of the recovery.
Transport can add challenges, mainly due to the hazardous nature of catalysts, but also due to the high value of the material. There are significant risks involved and specialists will help guard against any issues between your plant and your refiner.
And finally, settlement. What is the most efficient method to receive the value for your spent catalyst? Well, this depends on how you prefer to manage your plant, and this should form part of the initial assessment.
- Metal on account – return the recovered metal to your catalyst supplier to be used for fresh catalyst
- Receive the financial value for the recovered metal
- Receive physical metal
- Hold the metal on account
There are pros and cons which are specific to your business that need to be considered and discussed with specialists.
As you can see from the charts in Figure 2, metal prices have been erratic in recent years and the impact on your business may be significant.
Yes although:
- Specialists cost money
- Specialists need to be managed
- Specialists may not do a better job than we already do
While these comments may have some truth, the reality is that catalyst is rarely managed properly in-house because, as we discuss at the beginning, a chemical plant is rightly focussed on manufacturing product, and it is likely that there is no responsibility for the successful management of valuable catalyst. Parts of the catalyst management chain may be managed well but overall; your process is only as strong as the weakest link.
In the earlier example where a manufacturer was facing losses of 25%, the spent catalyst was not weighed prior to being shipped for refining and the drums contained 80% water. This makes it impossible to manage your metal and to have any control over such a valuable process. It is also common for vessels and ducting to become saturated with catalyst deposits and the metal moves further down the process and can end up in the product, impossible to recover. Installation of filtration systems, handling procedures and a regular cleaning schedule has captured the metal being previous lost.
In recent years nitric acid plants, which employ large woven PGM catalyst gauzes, have taken steps to bring in specialists to manage catalyst and recover lost material to improve overall recovery. Lost PGM from the catalyst is obvious and significant in this case – also plant efficiency is reduced by catalyst residues settling in the boiler and heat train. Regular specialist cleaning, carried out in the right way, can both capture the lost metal and bring plant efficiency back to where it should be. If the plant is not cleaned, then efficiency is reduced, and metal residues are lost in the product and spread on farmers’ fields. It happens.
Correct catalyst management now being enjoyed in the nitric acid industry should also be implemented in chemical and pharma to help achieve similar performance advantages and significantly reduce metal losses.
All the required specialists can be managed by one main contractor who controls all activities and is ultimately responsible for delivering an improved catalyst management service and added value. The financial benefits of reduced internal labour and increased recovered metal will far outweigh any costs incurred during the process and greatly reduce the risk of financial losses.
What have we learned?
Hopefully, nothing. Hopefully, you already carry out regular assessments, use the right personnel to carry out the recovery activities, understand the refining landscape, use the most efficient processor(s) for your material, handle and transport your material safely and efficiently, closely monitor metal markets and receive settlement in the most efficient way for your business. If, however, this has helped you to identify a potential opportunity for improvement to the environment, your plant efficiency, or your bottom line then you may consider talking to specialists.
Sky Metal Services works with chemical and pharmaceutical plants to carry out assessments, produce detailed plans, select, and manage the right specialists to provide a complete, efficient, and valuable catalyst management service.
About The Author
Chris Boulton is a UK based specialist in precious metal recovery and refining. He runs Sky Metal Services which ensures its clients’ precious metal is managed and refined in the most suitable way. By employing the most suitable specialists for the required tasks catalyst recoveries are maximised and risks to the plant are minimised.
All catalyst materials are different and sending multiple material streams to one refiner or processor may not be the most efficient method. Sky Metal Services assess the material in detail and ensure that it is refined by the most appropriate refiner and process to help ensure the maximum amount of metal, and therefore value and resource, is recovered.
Chris is available to help at chris@skymetals.co.uk.