AMDEA

Hybrid solvents combine the best characteristics of both the chemical and physical solvents and are usually composed of a number of complementary solvents. Hybrid solvents have out-performed existing solvents and those developed for one application have been easily adapted for to others. However this is not always desirable and the tendency has been to develop tailor-made solvents using complementary solvents where the proportions are varied to suit the applications. Typical solvents are aMDEA, Purisol, Sulfinol and UCARSOL199. 

The aMDEA (Activated Methyl Diethanolamine) process removes CO2, H2S and trace sulfur compounds from natural gas and syngas via a pressurized wash with activated diethanolamine. This process was developed by BASF. The first unit was started up in 1971 in Germany and in 2002 it was used in more than 140 plants with 20 more under construction1. About 75 of these plants involve another process technology (MEA, DEA, Benfield, etc.) that was modified to use the aMDEA technology. 

The aMDEA solvents are non-corrosive due to their chemical structure. This allows a high sour gas loading and therefore reduced solvent circulation rates, which results in low investment and low operating costs. 

CO is converted to C02 in the HT and LT shift over standard catalysts. C02 is removed in a scrubbing unit, which is normally either the BASF-aMDEA or the UOP-Benfield process. Remaining carbonoxides are reconverted to methane in the catalytic methanation to trace ppm levels. 

OmniSulf A process for removing C02, H2S, and mercaptans from acid gases. A joint development of Lurgi and BASF, based on the aMDEA process. 

Alkanolamine MEA processes aMDEA Hot poptash processes Selexol Selexol Fluor solvent Fluor solvent Purisol Purisol Rectisol Rectisol Sulfinol D Sulfinol D... 

The second version has a S/C ratio of 2.5 and shift conversion with medium- and low-temperature catalysts, both copper-based. For C02 removal Selexol or aMDEA is chosen. The synthesis is performed at 140 bar with a Topsoe two-bed S 200 radial converter, followed by a single-bed radial S 50 converter (S 250 configuration). After the converters, high-pressure steam is generated. An additional proprietary item is the side-fired reformer. 

Key features are the high reforming pressure (up to 41 bar) to save compression energy, use of Uhde s proprietary reformer design [1084] with rigid connection of the reformer tubes to the outlet header, also well proven in many installations for hydrogen and methanol service. Steam to carbon ratio is around 3 and methane slip from the secondary reformer is about 0.6 mol % (dry basis). The temperature of the mixed feed was raised to 580 °C and that of the process air to 600 °C. Shift conversion and methanation have a standard configuration, and for C02 removal BASF s aMDEA process is preferred, with the possibility of other process options, too. Synthesis is performed at about 180 bar in Uhde s proprietary converter concept with two catalyst beds in the first pressure vessel and the third catalyst bed in the second vessel. 

Synthesis operates at 82 bar in a proprietary tubular converter loaded with a cobalt-enhanced formulation of the classical iron catalyst. Purge gas is recycled to the PSA unit, and pure COz is recovered from the PSA waste gas by an aMDEA wash. Very little steam (60 bar) is generated in the synthesis loop and from waste gases and some natural gas in the utility boiler in the utility section, and all drivers are electric. 

Meibner, H., Wammes, W., and Hefner, W., Improving the performance of BASF s AMDEA-process by optimization of the activator concentration, Nitrogen, 91 151-164 (1991). 

Blended amine solvents are proposed to combine the advantages of each component. The optimal recipe typically comprises a principal solvent with high net CO2 capacity and an activator exhibiting fast reaction kinetics to improve the efficiency of both the absorption and regeneration processes. A successful example is activated MDEA (aMDEA) developed by BASF [16], which presents the merits of moderate energy requirement, excellent chemici stability and improved reactivity. In this work, we investigate two additional blended solvent systems AMP+PZ and DMAE+PZ. 

For example, Benfield process (UOP) and aMDEA process (BASF). 

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