Bis(2,2‐dinitropropyl)acetal/formal (BDNPA/F or A/F) is a nitroplasticizer ingredient used in military explosive/propellant formulations and applications. Several issues are associated with the chemical BDNPA/F production process. The synthesis of potassium 2,2-dinitroethanate (KDNE), the immediate synthetic precursor to 2,2-dinitropropanol (DNPOH), which is an intermediate in the synthesis of several important DoD materials including BDNPA/F, results in the formation of large amounts of corrosive salt waste. In order to produce roughly 200,000 pounds of DNPOH, it is estimated that more than 2.5 million pounds of hazardous waste would be generated. The production of DoD-related polynitroalkanes via electrochemical (EC) routes promises to drastically reduce the associated waste streams and enable the production of such energetic ingredients in a more efficient and environmentally responsible fashion.
The objective of this project was to design, build, and operate a pilot‐scale EC cell and equipment and demonstrate production of KDNE. The development and optimization effort focused on determining scalability of the reaction and refinement of the economic feasibility and manufacturing scale potential. The size‐of‐scale was to be at the pounds‐per‐hour level.
While the previous SERDP Exploratory Development (SEED) project (WP-1345) demonstrated the feasibility of electrosynthesis of DNPOH, the chemistry and process development required further study and optimization. This follow-on project optimized the electrochemistry and identified important process-related information from bench-scale operations and pilot-scale demonstrations at the pound-per-hour level. The project was carried out in three phases consisting of laboratory-scale development, pilot-plant construction/operation, and optimization of the EC process and subsequent conversion of the KDNE to DNPOH.
The bench‐scale process for the EC production of KDNE was successfully demonstrated on the pilot‐scale at ATK Launch Systems. Through a collaborative effort with Idaho National Laboratory and Electrochemistry, Inc., the pilot‐scale set‐up was designed and built in the M‐346 energetic materials synthesis facility at ATK. The production of high‐purity KDNE was realized at the rate of 1 pound per hour of cell operation. The KDNE was then converted in the laboratory to high‐purity DNPOH by treatment with formaldehyde and phosphoric acid. A competitive cost-based analysis of the EC process compared to the traditional chemical synthesis proved that substantial savings can be realized in the EC route, both in material and disposal expenditures. Stability of multiple solution phase equilibria in the anolyte was the most challenging aspect and is a topic that warrants additional investigation. Nonetheless, these results are promising and with further optimization it is envisioned that this research will lead the way to an economically and environmentally sound route for the production of DNPOH and ultimately BDNPA/F. It is likely that this process can be used for the EC synthesis of an array of other explosive compounds that are classically produced by oxidative nitration reactions.
The production of DoD-related polynitroalkanes via EC routes promises to drastically reduce the waste streams associated with chemical production processes, thereby enabling the production of such energetic ingredients in a more efficient and environmentally acceptable fashion.