The goal of a hybrid process to convert coal to liquids is to optimize processing of a mix of fossil and renewable energy resources such that in the aggregate the integrated process minimizes the emissions of green house gases (GHG) in an efficient and cost effective method. WRI hybrid process uses coal pyrolysis/direct liquefaction in addition to char/residue gasification and CO2/methane reforming to produce the balanced syngas necessary for thermo catalytic synthesis to jet fuel. Carbon emissions benefits are derived from co-liquefaction/co-pyrolysis of coal and biomass, by the use of syngas instead of pure hydrogen for hydrotreatment and by recycling of CO2 for methane reforming and char gasification. An added benefit is that the process also reduces the overall water requirements. A rudimentary analysis of such an integrated WRI hybrid CTL system indicates fewer GHG emissions in the production of jet fuel than from a typical oil refinery, assuming the energy sources as 51% coal and the balance natural gas and biomass. This project proposes to complete the simulations necessary to optimize the production of jet fuel with the least CO2 emissions given the hybrid system conditions.
|10 C12H6 + 40 H2 → 7 C12H20 + 36 C|
10 C12H6 → 2 C12H20 + 96 C + 10 H2
C12H20 + 3 H2 → C12H26
C12H6 + 13 H2O + 1.5 O2 → 8 CO + 16 H2 + 4 CO2
3 CH4 + CO2 + 2 H2O→ 4 CO + 8 H2
12 CO + 25 H2 → C12H26 + 12 H2O
|CTL by direct liquefaction|
CTL by pyrolysis
Jet fuel from coal liquids
Syngas by coal gasification
Syngas by methane reforming
Jet fuel from syngas
WRI Hybrid System
The proposed process will have two main sources of product jet fuel. The first source will come from the liquid product of the DCL/pyrolysis reactors combined with hydrogenation and hydrotreatment. The second source of jet fuel will come from an integrated synthesis system that will utilize the syngas produced by char gasification and methane reforming.
Synthesis will follow a proven route for synthesis of olefins. The initial step is the synthesis of methanol over a commercially available catalyst. The methanol is then utilized to synthesize olefins over an acid-zeolite based catalyst. Once the olefins are synthesized, they are oligomerized over a zeolite and poly-phosphorous catalyst in a solvent-washed reactor and fully hydrogenated into the final jet fuel product. This is then combined with the liquid product from the DCL and pyrolysis steps to give the final plant product.
The components of the hybrid CTL system, coal pyrolysis, char gasification and dry methane reforming have all been operated at commercial scales. However the combined system has not. A jet fuel plant based solely on coal would require large resources of water and oxygen and produce large amounts of GHG emissions. A hybrid resource system that includes biomass and natural gas in addition to coal would have much lower carbon dioxide emissions.