PTQ Q2 2022 Issue

Rejuvenated catalysts optimise refinery margins in high severity ULSD applications

Rejuvenated catalysts comparewell with fresh catalysts for performance in high pressureULSD applications with added cost savings


A cross the world, slowed growth in fuel demand, weak profit margins, strict environmental regulations on CO 2 emissions, and legislation on renewable fuels are s ignificantly impacting the refining industry. As a result, there is a greater need to optimise refining costs and maxim - ise profitability. The cost of replacing a catalyst at the end of its life is substantial, so it is important to choose an appro- priate catalyst. Evonik’s Excel reju - venated hydrotreating catalyst for ultra-low sulphur diesel (ULSD) applications can help refiners reduce operating costs and max - imise profitability while remaining environmentally conscious with their hydrotreating applications. 1 In this article, we compare the perfor- mance of this catalyst with its fresh counterpart in a parallel test at hte. What are rejuvenated catalysts? In a diesel hydrotreatment reactor (ULSD application), catalysts are typically replaced every two to four years, depending on the severity of the unit. ULSD catalysts deactivate mainly due to coke deposition over their lifetime. To recover the activ - ity of the catalyst, coke is removed by carefully burning it under mild oxidative conditions. Referred to as regeneration, the active sites over the catalyst may sinter or agglom - erate due to exotherms during this process. Rejuvenation allows for the selective removal of metal contam- inant deposits, restoring the spent catalyst’s activity to near fresh. 1-2 Excel rejuvenation enables the redispersion of agglomerates on the

regenerated catalyst to restore its activity to fresh by utilising a pro - prietary chemical treatment. Evonik’s hydroprocessing solu - tions can achieve the following benefits: • Reduction of the catalyst refill cost by about 50% compared to fresh catalyst • Faster catalyst supply compared to long lead times for fresh catalyst • Better environmental footprint, since these hydroprocessing solu - tions decrease CO 2 emissions, pre- serve natural resources, and avoid catalyst waste being sent to landfill • Similar performance compared to fresh catalyst in terms of activity and, more importantly, in terms of stability Using Excel rejuvenated catalysts, compared with fresh catalyst pro - duction, CO 2 emissions are reduced by approximately 6000kg CO 2 per ton of fresh catalyst replaced, thereby significantly contributing to the circular economy. Over the last five years, Evonik has successfully supplied more than 8000 tons of Excel rejuvenated catalyst to refin - eries worldwide, resulting in 48 000 tons of CO 2 not being emitted to the atmosphere. To demonstrate the robustness of these rejuvenated catalysts, inde - pendent catalyst testing and com - parison was performed at hte, the high throughput experimentation company. In this study, different Excel rejuvenated NiMo catalyst configurations were compared with their parent fresh material. The commercial NiMo catalyst is a well-proven, high activity catalyst for producing ULSD at moderate

to high pressure when sufficient hydrogen is available to maxim - ise its hydrogenation activity. It is designed to maximise nitrogen and sulphur removal with increased hydrogenation for polyaromatic conversion and volume gain. In addition, the same Excel rejuve - nated NiMo catalyst was loaded as a standalone in a commercial ULSD unit. This article also pre - sents commercial data comparing Excel rejuvenated NiMo with a fresh alternative NiMo catalyst to illustrate the stability of the Excel catalysts. Experimental The test was performed in an X4500 trickle-bed high through - put test unit at hte’s laboratories in Heidelberg. This state-of-the- art reactor system has consistently proven to be an excellent tool for comparing different catalyst sys - tems head-to-head under identi- cal conditions. In addition, the test unit was equipped with individu- ally heated reactors, allowing for the simultaneous testing of differ - ent reactor temperatures. 3 Catalyst testing was performed at multiple temperatures while having the same pressure, hydrogen-to-oil ratio, liq - uid hourly space velocity (LHSV), and hydrogen purity. The performance of Excel reju - venated NiMo was compared with its parent fresh catalyst by load - ing the rejuvenated NiMo catalyst as a standalone or as stacked beds, with either fresh NiMo or Excel rejuvenated CoMo catalyst, as per the loadings shown in Figure 1 and Table 1 .

PTQQ 2 2022 49

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