Gasoline hydro processing

The process of hydro-cracking was already developed in 1927 by the German company I. G. Farben Industrie, to transform lignite into gasoline. As a support for thermal or catalytic cracking, hydro-cracking is used nowadays to crack hydrocarbons that are more difficult to crack. 

The foregoing reactions are highly exothermic and significantly raise reaction temperatures. The MRG process, however, docs not involve such adverse side reactions with use of a special, selective hydiodesulfuriziiig catalyst (developed by Japan Gasoline Co. and Nikki Chemical). The MRG process uses part of product gas for hydrodesulfunzation, and even if it contains only 20-25% hydrogen and as high as 20-23% carbon oxides, only the proper hydro desulfurization reactions take place, The MRG process features a recycle use of product gas for hydrodesulfurization purposes without any special treatment. 

The principal product is ethylene. The higher products are rich in olefins (66% olefins in C3 + C4 which are 41% of total). Like Mobil MTO, this process also produces a good quality gasoline and a heavy gasoline which may require hydro-treatment prior to use. 

Fig. 4 A schematic of a CD Hydro/CD HDS process for production of low-sulfur gasoline. FRCN, full-range catalytic naphtha LCN, light catalytic naphtha MCN, medium catalytic naphtha HCN, heavy catalytic naphtha.

This combined process could produce low-sulfur gasoline at half the current cost of desulfurization and won the Brian Davis Refining Technology award in 1999. The start-up of the first CD Hydro/CD HDS unit was at Irving Oil s St John, New Brunswick Refinery, Canada, in 1999 and produced less than 150 ppm In 2000, Irving Oil received a U.S. Environmental Award. In 2004, the CD Hydro/CD HDS process was used to process about 1.0 million barrels per day of gasoline for mercaptans and sulfur removal in refineries all over the world. 

These considerations led us to studies of the combined processing of pyrolysis gasoline and gas oil. Catalyst performance, in particular, was recognized as a critical factor. When it was determined that catalyst life of available commercial hydro-treating catalysts was too short to give the desired plant onstream time, catalyst development became an integral part of the effort. 

The Mobil methanol-to-olefins (MTO) process may seem to be an abridged version of the MTG process, but the distribution of olefins is governed not only by the process conditions, but largely by the architecture of the zeolite, with ZSM-5 being the best option for the modification. In this case, smaller-pore zeolites (ZSM-34, SAPO-34) show excellent results so far as the olefins formed should not be transformed into gasoline. The latter zeolite-like material developed and commercialized by UOP jointly with Norsk Hydro provides the selectivities to ethylene and propylene above 85% at the 100% methanol conversion [113]. 

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