Efficiency Estimation and Improvement of the 1,3-Butadiene Production Process from Lignin via Syngas through Process Simulation

Three processes for the production of 1,3-butadiene (1,3-BD) from lignin via syngas were proposed, and their 1,3-BD yields and input energy, such as electric power and heat loads, were estimated through process simulation. These processes consisted of lignin gasification, conversion of syngas to light olefins (LOs) via (1) dimethyl ether (DME), (2) methanol, or (3) direct synthesis, and isomerization/dehydrogenation of <i>n</i>-C<sub>4</sub>H<sub>8</sub>. The process capacity was 200 t/d on a wet lignin basis. The electric power was largely dependent on the process (4777–6073 kWe), while the minimum external heat was 97 kW, according to pinch analysis. When each reaction proceeded ideally, the process featuring the conversion of syngas to LOs via DME was the most promising. The high electric power (6008 kWe) for the process was attributed to excess N<sub>2</sub> production through a cryogenic air separation method. A decrease in the amount of N<sub>2</sub> supplied to the DME-to-LOs unit led to a decrease in the electric power to 5381 kWe, and the 1,3-BD yield increased to 14.2 wt %. In the DME-to-LOs step, the feed gas with >8.7% DME and a reaction temperature of ∼280 °C were favorite conditions for further improving this most promising process.