Catalysis 2023 Issue

Reactivated catalysts can offer sustainability benefits in TGTUs Refiners can reduce operating costs and carbon emissions while retaining performance through conversion of reactivated hydroprocessing catalysts as tail gas catalysts for TGTUs

Brian Visioli Evonik Catalysts

I t is no secret that the world relies on catalysts in many aspects of life. They are proven to improve the qual- ity and standard of living thanks to their wide range of applications, including the manufacture of fine chemicals, agriculture, health care, and food products. However, the world in which these processes were established has changed, with many industries – not least the chemical manufacturing industry – facing a host of new challenges, most notably around sustainability. With surging energy prices and pressure to reduce envi- ronmental footprints, the spotlight is on the industry to reform and revitalise its operations to reduce waste, cut pol- lution, and minimise impact on the environment. Alongside the transition to greener, more sustainable manufacturing processes, refiners are having to contend with seemingly ever-rising costs, with events such as the Ukraine-Russia conflict putting a strain on the global economy. On top of this, experts are predicting a mild global recession in 2023. These external factors have placed further pressure on refineries to find cost-effective methods to complete their operations without compromising performance or safety levels. The million-dollar question is, how can refineries reduce their operating costs and carbon emissions while maintaining levels of performance? The answer: through catalyst reuse. Here we explore how replacing fresh tail gas catalysts with reactivated hydroprocessing catalysts can yield significant environmental benefits and cost savings for refiners while ensuring equivalent performance and consistency of production methods. Reactivating hydroprocessing catalysts Reusing hydroprocessing catalysts via ex-situ regenera- tion and/or rejuvenation treatment has long been common practice in the global petroleum industry to provide cost- advantaged catalyst configurations with similar or equiva - lent performance to fresh catalysts. Catalyst recycling not only extends the useful life of catalysts but also substan- tially reduces the quantity of hazardous spent (used) cata- lyst waste sent to landfill and reduces the carbon footprint of catalysis on industrial scales. Due to these benefits, it is easy to see why catalyst reuse schemes have been imple- mented in the refining industry for more than 40 years. To put this in context, 154,000 MT of hydroprocessing catalysts are replaced in refineries each year, more than

20% of which are catalysts that have been regenerated or rejuvenated via ex-situ processes. This translates to the installation of more than 30,000 tons of regenerated and rejuvenated hydroprocessing catalysts per year. At the end of an operational cycle, a hydroprocessing catalyst is removed from the reactor, classified as hazardous, and dis - posed of via one of three methods. Disposal in a hazardous waste landfill is the least desir - able option as the refiner loses the value within the spent catalyst, a fee must be paid, and the environmental impact must be considered. Processing for metal reclamation is a more favourable approach. However, while refiners can be credited a fraction of the value of certain components reclaimed from the spent catalyst, this method is energy intensive and still leaves a potentially environmentally harmful waste stream that must be disposed of. Catalyst recycling not only extends the useful life of catalysts but also substantially reduces the quantity of hazardous spent (used) catalyst waste sent to landfill Moreover, both options involve processing costs, and nei - ther leverages the value of the technology inherent in the catalyst particle for the refiner’s benefit, which is why the third option – catalyst reuse – is the most preferred. This is where refineries can take full advantage of all useful mate - rials in their spent catalyst by reactivating them in order to use them again. The process involves oxidation under controlled con- ditions to remove carbon and sulphur compounds but preserve catalyst qualities for certain applications (an additional chemical treatment, commonly referred to as ‘rejuvenation’, may also be employed). Ultimately, it allows the refiner to leverage the maximum value of their spent catalyst, avoids the economic and environmental impacts of landfill disposal, and gives the active metal compo - nents, which comprise a hydroprocessing catalyst, a ‘fresh start’. And equally important, regenerating and reusing the

Catalysis 2023