Decarbonisation Technology – August 2021

Figure 1 shows detailed current and announced refinery conversions to biofuels and COTC. With these transformations, new technologies to produce green hydrogen will be critical to achieving the energy transition. Catalysts and adsorbents in crude oil to chemicals refineries The main objective of a COTC refinery is to convert oil to chemicals, from a traditional refinery conversion of 8-12% to more than 50%, even to 70-80%. 2 To achieve this ambitious modification, researchers, catalysts companies and licensors have been working hard for many years to develop different proposals. The best solution would be a unique multifunctional catalyst that could transform the oil into chemicals, crack, dehydrogenate, remove sulphur and all the desired reactions. Researchers at King Abdullah University of Science and Technology (KAUST), in partnership with Aramco, have recently designed a new catalyst based on zeolites, clay and silicon carbide to convert Arabian Light crude into light olefins, with yields per pass of over 30 wt% and minimum production of dry gas, in a single reactor system. In parallel to developing this unique multifunctional catalyst, the industry is tackling the COTC strategy in three different ways, as already pointed out in 2017 by Dr Avelino Corma: 4 ➊ Direct processing of crude oil in steam cracking This process requires preconditioning of the crude oil before being fed into the steam cracker to avoid too much coke formation. The

steam cracker requires a packing bed and a catalyst bed. This catalyst bed may be disposed of at the bottom of the vaporiser to enhance cracking, and will help to remove metals such as Ni, Fe, V and trap non-vapourisable material such as asphaltenes. Materials such as alumina, silica- alumina, molecular sieves and natural clays may be used. Industrial references for this technology come from ExxonMobil (Singapore refinery) and Shell. ➋ Integrated hydroprocessing/deasphalting and steam cracking Saudi Aramco has patented an integrated hydrotreating, steam pyrolysis and coker process for the direct processing of crude oil to produce olefinic and aromatic petrochemicals. In this scheme, the role of the hydrodemetalisation catalyst before the hydroprocessing catalyst is vital to protect it. 5 ➌ Processing of middle distillates and residues using new hydrocracking ebullated bed technology This scheme has been adopted by Hengli Petrochemical Ltd to produce diesel and naphtha range stream, which can later be processed to produce aromatic compounds. 6 In these new COTC schemes, the most affected processes produce naphtha, which is the source of olefins and aromatics, feeds to chemicals. These processes are fluid catalytic cracking (FCC) and hydrocracking. In hydrocracking, new developments present ebullated catalytic beds, as in Axens H-Oil process. 7 In this process, fresh catalyst is continuously added to the reactor, and the spent

catalyst is withdrawn to control the level of catalyst activity. This technology provides higher conversion and no limit on catalyst life compared to traditional fixed beds. Other hydrocracking technologies with moving catalytic beds are LC- fining, from CLG, VCC from KBR, EST from Eni, Uniflex from UOP and

The key role of Catalysts and Adsorbents in Energy Transition

Dr. Meritxell Vila

Catalysis and Chemical Science

Catalysis Webinar, 24-25 March 2021