(680a) Bio-Based Pyrrolidone from Succinic Acid: Process Design and Life Cycle Assessment

Bio-based chemicals are a possible pathway to reduce the carbon emissions of the chemical industry. Thus, many bio-based process routes are currently under development. One of these process routes is the bio-based production of succinic acid, which is already established on an industrial scale. However, succinic acid is limited in its applications and thus in its market. The market for succinic acid has been recently expanded by the development of a new process route from succinic acid to the high-value chemical N-vinyl-2-pyrrolidone (NVP) by Haus et al. 2019. The market for NVP is expected to grow by 8.5 % p.a., reaching a total volume of 2.75 billion dollars by 2024. In combination with its current market price of NVP of around 5000 $/tonne, this makes NVP an attractive target as a bio-based chemical. However, for new bio-based chemicals, it is essential to evaluate the potential to reduced environmental impacts compared to its fossil-based counterpart, since a reduced impact is not guaranteed.

In this work, we thus conduct a comparative Life Cycle Assessment of n-vinyl pyrrolidone to examine the environmental advantages and drawbacks of bio-based NVP production. The functional unit of the LCA study is 1 kg of NVP and we apply cradle-to-grave system boundaries. The production system for the bio-based NVP includes the cultivation of four potential bio-feedstocks (corn, corn stover, sugar beet, and sugar cane), the fermentation of sugar to succinic acid, and the newly developed processes for the conversion of succinic acid to NVP. The production system for the fossil-based NVP includes the production of maleic anhydride based on butane, the conversion of maleic anhydride to gamma-butyrolactone, and the conversion of gamma-butyrolactone to NVP. Since no data on the conversion of gamma-butyrolactone to NVP is available in commercial databases, we modelled this process step in commercial flowsheeting software based on available patents.

To generate the inventory for bio-based NVP production, we design a process for the production of bio-based NVP and generated a flowsheet model based on lab results. The bio-based NVP production is based on a two-stage reaction: In the first reactor, succinic acid is amidated with ethanolamine and then hydrogenated with a ruthenium catalyst in a water phase to form N-(2-hydroxyethyl)-2-pyrrolidone (HEP). Succinic acid is converted to HEP with 70 % yield. Various by-products are formed, including an uncharacterized oligomer. After the first reactor, HEP is purified. For this purpose, HEP is first separated from the oligomer and water in an extraction column using dichloromethane as solvent. Afterward, HEP is separated from dichloromethane and by-products in a distillation column. HEP is then vaporized and dehydrated to NVP in a gas-phase reaction at 350 °C in the second reactor. This reaction takes place with above 99% conversion and 95% selectivity. By-products and educts are separated via distillation.

The LCA shows that the bio-based production of NVP reduces the environmental impact significantly compared to fossil-based production. Depending on the used feedstock, global warming impacts are reduced by 45-60 %. Production of succinic acid has the largest contribution to the overall environmental impact, followed by feedstock production. Increasing the selectivity of HEP in the first reaction step could further improve the bio-based process.

Thus, the bio-based production of NVP from succinic acid increases not only the economic potential but also reduces carbon emissions compared to its fossil-based counterpart and thus shows a large potential as a new bio-based production route.