Catalysis 2022 issue

ing FCC unit operations. Clariant has various options to improve FCC feed viscosity in FCC pretreaters with Clariant’s HYDEX Series catalysts, including mild hydrocracking and beyond. A NievesÁlvarez,,Meritxell Vila,, MERYT Catalysts & Innovation To improve the conversion performance of our FCC, we can consider three different actions: 1. Revise the quality of the HCK bottom residue: It is important to have a detailed analysis of the HCK bot- tom residue: the content of aromatic carbon, naphthenic carbon, and its distribution. If we want to increase yields in the FCC, this residue should have a high naph- thenic carbon content and a low triaromatic+ in the aromatic carbon distribution. Of course, these contents depend on the aromatic feed content, on the tempera- ture of the hydrocracker unit, and on the catalyst capac- ity to convert aromatics into naphthenes. We recommend performing some changing reaction temperature testing of the hydrocracker to obtain the best conditions to produce maximum HCK residue with maximum carbon naphthene. This should be tested for each VGO quality to the HCK and the catalyst in use. Pay attention to these tests results regarding the residue and the other products and the qualities you need to obtain in the hydrocracker, such as sulphur and metals. 2. Adjust the cutpoint of the HCK bottom residue: to obtain more yield (m 3 /h or kg/h) in FCC is to increase the feed quantity. This yield increasing, of course, depends on the products you need to obtain in your FCC. If you want to produce more LCO or naphtha, you could reduce the HCK residue you send to the FCC, making this FCC feed lighter and decreasing the cat/oil ratio. Conversion will be adjusted with riser tempera- ture and maximum regeneration limits. But if you want to produce more olefins, you could increase the FCC feed until maximum riser cat/oil with riser tempera- ture, considering maximum regenerator temperature GasCon limits. 3. Make an integrated evaluation of both units: HCK and FCC. We recommend making an integrated evalua- tion of both units regarding the performance of all the catalysts involved and the processes and, therefore, doing an integrated economic balance. It may be that the best catalyst for the FCC is not the best when we evaluate the yields and economy integrating both units. Alternatively, the upgraded catalyst for HCK may not be the optimum when we do the global evaluation of the performance of both units. The best way is to evaluate the impact on both units when you evaluate the catalysts with the help of pro- cess simulation models A Eelko Brevoord, Consultant, Catalyst Intelligence Sarl, To boost FCC performance, the mild hydrocracker product should have the following features:

1. Minimum nitrogen content 2. Maximum hydrogen content

In mild hydrocracking (MHC), the reactor tempera- ture is usually maximised immediately from start of run (SOR) to obtain maximum conversion of feed to diesel. At SOR, this leads to product quality give-away, as the catalyst activity is still very high, and the reactor temperature does not need to be maximised to meet, for instance, product sulphur requirements. The conditions for the best FCC operation should be optimised over the full cycle, which does not necessarily mean that you maximise reactor temperature at SOR. This is especially valid as MHC units operate at relatively mild pressures, and at high temperatures, aromatics saturation is not favoured. Consequently, hydrogen addition is not opti- mal if you focus only on the conversion in the MHC unit itself. Overall, we can conclude that an operation at the highest aromatics saturation point and the lowest nitrogen content over the cycle is optimal. It is recom- mended to do a sophisticated modelling study to obtain the best operating strategy. Catalyst Intelligence has developed the HydroScope model, which can optimise the MHC unit with the FCC operation in mind. Q What level of SOx emissions from the FCC should we expect from current catalyst additives? A Corbett Senter, Regional Marketing Manager – Refining Catalysts. Europe, Middle East, & Africa, BASF, james. SOx emissions from FCC depend on several factors (not just additive usage and performance), as SOx emission and the mechanism of SOx additives are both multi- step processes. SOx is formed when sulphur in feed enters the regenerator either as coke or due to poor stripping of FCC product from the circulating catalyst after the reactor. The sulphur in the regenerator is then combusted to SO 2 and SO 3 which can leave the FCC as emissions. SOx additives function by capturing SO 3 in the regenerator, reducing the captured S-oxide on the additive in the riser and enabling conversion of S-oxide to H 2 S in the stripper, which causes the sulphur to exit with effluent from the reactor. Thus, the amount of sulphur in feed, feed type (type of sulphur compounds and metals in feed), stripper performance, catalyst cir- culation rate, regen operation, and the amount of SOx additive used will all play a role in SOx emissions. The key to understanding the expected emissions levels is to consider all these factors to develop a plan for reducing SOx emissions. A Victor Batarseh, FCC Technical Service Manager, W. R. Grace & Co., Units using SOx additives can achieve anywhere from 30 to >95% SOx emission reduction depending on unit configuration, operating conditions, additive usage rates, and feed quality. Low feed sulphur, full burn units can achieve the lowest SOx emissions at levels below 25 ppm utilising SOx additive alone, while par- tial burn units may only be able to achieve a 30-70%

Catalysis 2022 11

Powered by