MtSynfuels Process

Lurgi AG develops a process called MTSynfuels® (Methanol-to-Synfuels). Like Fischer-Tropsch-Processes (FT), the process is designed to produce liquid fuels from synthetic gases. Please see a schematic diagram illustrating the MtSyn-fuels®-process below.

The production of syngas and the synthesis of methanol

Like the FT process, syngas is the starting material for the MtSynfuels® process, which can be produced from various fossil fuels and renewable raw materials. The syngas must meet the same purity requirements and have the same composition (i.e. H2/CO = 2) as is usual for FT synthesis. The subsequent conversion of syngas to methanol is exothermic, as in the following reactions:

CO + 2 H2 –> CH3OH

CO2 + 3 H2 –> CH3OH + H2O

CO + H2O –> CO2  + H2

The methanol synthesis variant developed by Lurgi works at pressures of 50 - 100 bar and at temperatures between 220°C and 280°C with a Cu-Zn-Al2O3 catalyst.

The production of olefin

In the MtSynfuels® process the methanol is then catalytically converted to DME (Dimethylether) like this

2 CH3OH –> DME  + H2O

and then into hydrocarbons e.g. to

DME  –>  2/3 C3H6 + H2O

The zeolitic catalyser used for this step has a high selectivity for olefins. The conver-sion occurs at temperatures between 300°C and 550°C and at pressures between one and 20 bar.

The oligomerisation of olefin

The product mixture from the methanol conversion is then fed to the next reaction level, where the short-chain olefins are now built up (oli-gomerised) to larger molecules, for example to

4 C3H6  –>  C12H24

This reaction occurs at temperatures between 150°C and 350°C and at pressures between 35 and 85 bar, using a zeolitic catalyser. The oligomerised products in the area of C10+ are separated by distillation from the product mixture and hydrogenated. The resulting flow directly represents the diesel product of the MtSynfuels® process. Apart from that, during the distillation, a low-molecular gasoline product containing paraffin and aromatics is separated. For the two main products diesel and gasoline a total yield of > 90% (relating to carbon) is specified, whereby the ratio of diesel to gasoline can vary over a wide range. LPG (C3/C4) and light ends (C1/C2) are produced as by-products and water is also produced from the methanol conversion process.

Lurgi gives the energy efficiency of the process chain of 67% as an advantage over the FT path (< 63%). The overall efficiency, including all operating materials, is however about the same for both paths. The gasoline product from the MtSynfuels® process has a significantly better quality than the gasoline-like by-product of an FT systhesis.