The effect of ultrasound for impurities removal on spent catalyst from naphtha hydrotreater (NHT) processing unit

Solid catalysts are widely used to improve process efficiency in oil refinery industry, such as in Naphtha Hydrotreater (NHT) unit. In this unit, Ni/Mo catalysts are used. During the processing, the catalysts will be contaminated with impurities, such as (sulfur (S), iron (Fe), and arsenic (As), in the crude oil feed, then becomes deactivated over a period of time. Regeneration of the spent catalyst can be used as alternative method to reduce the generation of hazardous waste from spent catalyst. There are many methods to regenerate the spent catalyst such as leaching, microwave, and ultrasound. In this present study, the effect of ultrasound process in enhancing the removal of impurities on spent catalyst (Ni/Mo) was investigated. The mixture of spent catalyst (Ni/Mo) and water (1/20 (w/v)) was treated by ultrasound at 30°C, 20% amplitude, and various time (5-45 minutes). After ultrasound process, solid product was analyzed by Scanning Electron Microscopy (SEM), X-ray fluorescence (XRF), and Brunauer Emmet Teller (BET). The content of impurity in spent catalyst were decreased after ultrasound processing. At low temperature (30°C) and short time (25 min), the content of S was decreased from 17.3% to 1.8%, Fe from 13.1% to 2.4%, and As from 2.3% to 1.3%.