(139a) Hydrogen Generation From Heavy Oil | AIChE

(139a) Hydrogen Generation From Heavy Oil


Srinivas, G. - Presenter, TDA Research Inc.
Gebhard, S. - Presenter, TDA Research Inc.
Copeland, R. - Presenter, TDA Research Inc.
Martin, J. - Presenter, TDA Research, Inc.

Refineries in the U.S. are processing increasingly heavy sour crudes that contain metals, sulfur, and high molecular weight aromatic hydrocarbons. Many sour crudes originate in the Western Hemisphere, including heavy crudes from Venezuela, southern California, and the enormous quantities of oil sands in Canada. Processing and upgrading these heavy feedstocks requires considerable hydrogen. Unfortunately revamping or installing new hydrogen capacity with conventional technologies such as methane steam reforming or petroleum coke gasification is expensive.

TDA Research Inc. is developing a new technology that will allow hydrogen to be produced in refineries to at a cost that is considerably lower than hydrogen produced from conventional technologies, and also less expensive than purchasing hydrogen from a third party. This technology converts “bottom of the barrel” materials into hydrogen, which makes it possible to produce more distillate fuels from each barrel of oil, especially from less expensive heavy crudes that are available in greater quantity.

We refer to our process as Heavy Oil Gasification “HOG.” The primary advantage of HOG is that heavy oils can be steam reformed/gasified over nickel based catalysts to produce hydrogen without catalyst deactivation and without the need for an oxygen plant. This greatly expands the range of feedstocks that can be used to generate hydrogen by steam reforming, since the heaviest feeds normally used are naphthas.

The reason that we can steam reform/gasify heavy oil over nickel based catalysts without catalyst deactivation is that we do not use a fixed bed reactor. Instead, our process functions like a chemical looping steam reformer/gasifier. Heavy oil and steam are fed into a fluidized bed reactor containing Ni steam reforming catalyst at 870°C to generate syngas (CO + H2). Because the process uses a fairly short contact time, the amount of carbon that does build up on the catalyst is not enough to cause irreversible deactivation. The catalyst is then sent to a regenerator (in a configuration similar to the old ESSO FCC process), where the coke is burned off with air, partly reheating the catalyst. Additional heavy oil (or petcoke) is added to the regenerator since the amount of coke on the catalyst is insufficient to provide all of the heat needed to reheat the catalyst back to 870°C. The hot catalyst returning to the reforming reactor is now in the form of nickel oxide, which is catalytically inactive; however, in the HOG process, the hydrocarbons in the feed quickly reduce the NiO back to catalytically active Ni for the next reforming/gasification cycle. In an industrial sized unit, the sensible heat in the catalyst (and any inert solids added) would provide all of the endothermic heat required for the steam-hydrocarbon reforming/gasification reactions.

TDA has conducted an extensive series of tests with atmospheric tower bottoms (ATB) as the feed, along with a commercial nickel based methane-steam reforming catalyst , over a wide range of steam to carbon (s/c) ratios and found that we can operate with s/c as low as 5 while cycling the catalyst between reforming/gasification and regeneration. No catalyst deactivation has been observed as evidenced by no change is product selectivity or product yield. We are currently investigating other catalysts and heavier feeds as well as conducting long tests where the system will be cycled hundreds of times to determine the durability of the catalyst under more realistic conditions.



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