Traditionally, SA can be synthesized through chemical process from maleic anhydride through n-butane using petroleum as starting material; the high raw material cost of maleic anhydride limits the use of succinic acid for a wide range of applications. Recently efforts have been focusing on produce SA via fungal or bacterial fermentations through the TCA reactions because the increased market expected to come from the synthesis of biodegradable polymers; polybutylene succinate (PBS) and polyamides (Nylon®x,4) and various green solvents.
During biochemical pathways for SA synthesis, bacteria used mainly utilize the phosphoenolpyruvate (PEP) carboxylation reaction and the reductive arm of the TCA cycle. It requires CO2 input; Formation of by-products such as acetic, formic and lactic acid can be a major problem, but will be solved by improving the microbs and the fermentation conditions. Theoretically, redox balance gives 1.714 mol succinate per mol glucose or 1.12 g succinate each gram glucose.
The manufactering cost is mainly affected by succinic acid yield, productivity, raw material cost and utilization, and product recovery method. The technological efforts still need to reduce the cost of both aerobic and anaerobic fermentations – nutrients and carbon feedstocks; improve the robustness of fermentations, increase the productivity of organisms – a minimum of 2.5 g/(L. h) is needed for the process to be economically competitive; and ferment both 5 and 6 carbon sugars.
No comments:
Post a Comment